The mechanism for converting rotational motion into translational motion. Device for converting rotational motion into translational motion Mechanism for converting circular motion into swinging motion
Drives for implementing the rectilinear movement of the working parts of machine tools can be divided into mechanical, converting rotational motion into rectilinear (Figure 20, a-e), piston (Figure 20, g, h), magnetostrictive and thermodynamic.
Mechanical drives are divided into reversible and cyclic. In reversible drives, the direction of movement of the working element changes when the direction of rotation of the link that converts rotary motion into linear motion changes, using a reversible drive of rotational motion.
Reversible drives consist of a rotational motion drive I (Figure 20, a) with a reverse mechanism 2 and a link that converts rotational motion into linear movement of the working body 4. To convert rotational motion into linear motion, the following can be used: screw 3 (Figure 20, a), worm 2 and worm rack (Fig. 20b), spur, helical or chevron rack wheel 2 engaging with rack 1 (Fig. 20c), worm or helical gear 2, with an axis located at an angle to the direction of movement, engaging with rack 1 (Fig. 20d) and flexible transmission 2 (Fig. 20d).
Rice. 20 Mechanisms for linear motion
Depending on the nature of the movement of the working body, the rotational motion drive must ensure a change in speed in accordance with the given operating mode, a change in the direction of movement of the working body, and obtaining high speed in both or one direction. Depending on the requirements determined by the nature of the movement of the working body, the rotational motion drive has a more or less complex structure of mechanisms for changing the speed of working strokes, reverse and high-speed mechanisms, as well as a corresponding system of mechanisms for switching kinematic chains and control. All this leads to a more or less significant complication of the design of linear motion drives.
An important advantage of reversible drives is the ability to adjust the stroke length and the sequence of inclusion of fast and working strokes in accordance with the requirements of a specific technological operation, which determines the use of these drives on universal and specialized machines.
It should be noted that reversible drives are suitable for any maximum stroke length of the working element.
The smoothness, accuracy of movement, rigidity and efficiency of a reversible drive largely depend on the form of transmission used to convert rotational motion into linear motion.
The smoothness and accuracy are affected by kinematic accuracy and gaps in the transmission, which converts rotational motion into linear motion.
Let's look at the various gears used to convert rotary motion into linear motion in reversible drives.
The screw-nut transmission (Figure 20, a) can be performed with particularly high precision. According to the machine tool industry standard for screws of class zero, the permissible pitch deviations within one pitch are equal to ±2 μm, and the largest accumulated pitch error over a length of 300 mm is 5 μm. High manufacturing precision ensures high precision of movements with appropriate drive design.
Since the screw-nut transmission makes it possible to obtain a low speed of linear motion at a relatively large number of screw revolutions, the kinematic chains of the feed drives and installation movements when using this transmission consist of a small number of reduction gears, which leads to a simplification of the kinematics and design of the drive and to a reduction in its reduced moment of inertia compared to other mechanical drives.
Since the rigidity of the screw-nut transmission is determined by tensile or compressive deformations, as well as (to a lesser extent) torsional deformations, then with a large screw length and small diameter, the transmission rigidity may be insufficient, which negatively affects the smoothness and accuracy of movements.
A significant disadvantage of the described transmission is low efficiency. This disadvantage can be eliminated by using a screw-nut transmission with circulating balls in the nut. In this case, sliding friction is replaced by rolling friction, and efficiency increases to 0.9-0.98. Gears of this type are increasingly used in machine tools and primarily in various types of servo drives.
Screw-nut transmissions are widely used in kinematic profiling chains, feed drives and installation movements, where, with low drive power, efficiency is not significant, and the positive features of this transmission play a significant role.
In cases where the screw-nut transmission cannot be made sufficiently rigid, a worm-rack transmission is used (Fig. 20b), the rack of which is like a long part of the nut. Since a long screw of a relatively small diameter is replaced by a short worm, the transmission rigidity is much higher. However, the accuracy of the worm-rack transmission is lower than the screw-nut transmission, since the worm rack can only be made as a composite of individual pieces and cannot be made with the same high accuracy as a screw. The efficiency of this transmission is also lower, since the diameter of the worm, due to the design features of its placement, is much larger than the diameter of the screw, which leads to a decrease in the angle of elevation and, consequently, the efficiency of the transmission.
Worm and rack gears are used in cases where high drive rigidity is required to ensure smooth operation, and less stringent requirements are imposed on the accuracy of movements: in the feed mechanisms of longitudinal milling, boring, rotary and some other types of machine tools.
The rack and pinion transmission (Fig. 20, c), due to the larger errors in pitch and gaps compared to the screw-nut transmission, gives less smoothness and accuracy of movement. The transmission has high efficiency and relatively high rigidity; it is used in the drives of the main movement of planing machines and in the feed drives of lathes, turrets, drilling, boring and other machines.
In the drives of the main movement of planing machines, the rack and pinion gear has a large diameter, due to which the engagement duration coefficient and smooth operation are increased. For the same purpose, helical and chevron gears are used in the drives of planing machines. Due to the large diameter of the rack and pinion gear, it is necessary to introduce a large number of reduction gears into the drives, which leads to an increase in the reduced moment of inertia of the drive.
In feed drives, the rack and pinion gear is made with a small number of teeth 12-13. Correction is used to eliminate undercutting of teeth.
In the drives of longitudinal planing machines, rack and pinion gears, shown in Fig. 20, are widely used. They are made with a multi-start worm (a helical gear with a small number of teeth and a large angle of inclination). Such gears have a relatively high efficiency, ensure smooth running and reduce the number of reduction gears in the drive.
In some machine models, flexible connections are used to convert rotational motion into linear motion (Fig. 20e). A flexible connection 2 is attached to disk 1. Steel tape, wire, or cable can be used as a flexible connection. On the other hand, the connection is attached to the leash 3 of the working body 4. When the disk 1 is turned, the working body moves in a straight line. Flexible connections in the form of a steel strip and wire provide high precision of movement under light loads and are used in the running-in mechanisms of various gear-processing machines: gear grinding, for gouging bevel gears, etc.
In cyclic drives, unlike reversible drives, the direction of movement of the working element is changed with the help of the link itself, which converts rotational motion into linear motion, while the direction of rotation of the last link remains unchanged.
Cyclic drives include crank, crank-rotary and cam mechanisms.
Crank and crank drives can perform only some of the functions that are assigned to a linear motion drive.
Thus, the crank drive performs only the functions of a reversing mechanism when changing the direction of movement. The forward and reverse speeds are the same and vary along the stroke length. The stroke length is changed by changing the crank radius. With a large stroke length, the mechanism becomes cumbersome. This mechanism finds limited use with a short stroke length of 100-300 mm in the drives of the main movement of gear shaping and gear planing machines, where increasing the reverse speed does not provide a noticeable increase in productivity, in the feed drives of slotting and key milling machines. The crank-yoke mechanism makes it possible to obtain an increased return speed, which is a function of the working stroke and exceeds it relatively slightly. The speed along the stroke length is variable. Mechanisms of this type with a swinging and rotating slide are used in cross-planing and slotting machines with a stroke length of up to 900-1000 mm.
Cam mechanisms (Fig. 20, e) perform all the functions of a linear motion drive by giving the corresponding profile to the cam. A cylindrical cam 1 with a curved groove, into which a roller attached to the movable working body 2 fits, in section a has a steep rise corresponding to rapid forward motion, in section b there is a gentle rise corresponding to the working stroke, and in section c there is a steep descent corresponding quickly walk back. Thus, with the help of a cam mechanism, the required sequence of movement of the working body with a given speed and stroke length can be easily achieved, due to which cam mechanisms are widely used in automatic machines. The disadvantage of cam mechanisms is the need to manufacture special cams in relation to a specific technological operation.
Piston drives of rectilinear motion. With piston drives (Fig. 20g), the working body 2 in most cases is connected directly to the movable piston 1 or the piston drive cylinder, which makes it possible to significantly simplify the entire kinematics and design of the corresponding machine unit. Only in some cases, when particularly precise movements are carried out and the working bodies have a short stroke length, intermediate reduction gears are introduced from the piston drive to the working body (Fig. 20h).
Due to the simplicity of their design, piston drives of various types are widely used in machine tools.
The invention relates to mechanisms for converting rotational motion into translational motion. The mechanism contains an annular shaft, a sun shaft located inside the annular shaft and a plurality of planetary shafts. The ring shaft has an internal threaded portion and first and second ring gears, which are internal gears. The sun shaft includes an outer threaded portion and first and second sun gears, the sun gears being external gears. The planetary shafts are arranged around the sun shaft, each of the shafts including an outer threaded portion and first and second planetary gears, which are external gears. An outer threaded portion of each planetary shaft engages an inner threaded portion of the annular shaft and an outer threaded portion of the sun shaft. The first and second planetary gears each mesh with the first and second ring gears and the sun gears, respectively. In this case, the planetary shafts are configured to provide relative rotation between the first planetary gear and the second planetary gear. The solution is aimed at reducing wear on the mechanism and increasing the efficiency of converting rotational motion into translational motion. 14 salary f-ly, 9 ill.
Drawings for RF patent 2386067
Field of technology
The present invention relates to a rotational/translational motion conversion mechanism for converting rotational motion into translational motion.
State of the art
As a mechanism for converting rotational motion into translational motion, for example, a conversion mechanism disclosed in WO 2004/094870 (hereinafter referred to as Document 1) has been proposed. The conversion mechanism includes an annular shaft that has a space extending therein in an axial direction, a solar shaft that is located inside the annular shaft, and planetary shafts that are located around the solar shaft. In addition, external threaded portions formed on the outer circumference of the planetary shafts engage with internal threaded portions formed on the inner circumference of the annular shaft and external threaded portions formed on the outer circumference of the sun shaft. Thus, force is transferred between these components. The planetary motion of the planetary shafts, which is obtained when the annular shaft rotates, causes the sun shaft to move forward along the axial direction of the annular shaft. That is, the conversion mechanism converts the rotational motion supplied to the annular shaft into the linear motion of the solar shaft.
In the above-mentioned conversion mechanism, two gears are provided so that force is transmitted by the meshing of the gears in addition to the meshing of the threaded portions between the ring shaft and the planetary shafts. That is, said conversion mechanism includes a gear train that is formed by a first ring gear provided at one end of the ring shaft and a first planetary gear provided at one end of the planet shaft so as to mesh with the first ring gear, and a gear train that formed by a second ring gear provided at the other end of the ring shaft and a second planetary gear provided at the other end of the planetary shaft so as to mesh with the second ring gear.
In the conversion mechanism according to Document 1, when the rotation phase of the first ring gear is different from the rotation phase of the second ring pinion shaft, the planetary shafts are arranged between the ring shaft and the sun shaft in an inclined state relative to the original position (the position in which the center lines of the planetary shafts are parallel to the center line solar shaft). Thus, the engagement of the threaded sections between the ring shaft, planetary shafts and sun shaft becomes uneven. This increases local wear, correspondingly reducing the efficiency of converting rotational motion into linear motion. Such a problem occurs not only in the above conversion mechanism, but in any conversion mechanism including gears formed by the planetary shaft gears and the gears of at least one of the ring shaft and the sun shaft.
Brief description of the invention
Accordingly, an object of the present invention is to provide a rotational/translational motion conversion mechanism that suppresses the tilt of planetary shafts caused by the meshing of the planetary shafts and the gear of at least one of the ring shaft and the sun shaft.
To achieve this object, the first aspect of the present invention provides a rotational/translational motion conversion mechanism that includes an annular shaft, a sun shaft, a planetary shaft, as well as a first gear and a second gear. The annular shaft is provided with a space extending therein in the axial direction. The solar shaft is located inside the annular shaft. The planetary shaft is located around the solar shaft. The first gear and the second gear transmit force between the annular shaft and the planetary shaft. The conversion mechanism converts the rotational motion of one of the annular shaft and the sun shaft into a translational motion and along the axial direction of the other one of the annular shaft and the solar shaft due to the planetary motion of the planetary shaft. The planetary shaft includes a first planetary gear that configures a first gear train portion and a second gear that configures a second gear train portion. The planetary shaft is formed to allow relative rotation between the first planetary gear and the second planetary gear.
A second aspect of the present invention provides a rotational/translational motion conversion mechanism that includes an annular shaft, a sun shaft, a planetary shaft, as well as a first gear and a second gear. The annular shaft is provided with a space extending therein in the axial direction. The solar shaft is located inside the annular shaft. The planetary shaft is located around the solar shaft. The first gear and the second gear transmit force between the planetary shaft and the sun shaft. The conversion mechanism converts the rotational motion of one of the planetary shaft and the solar shaft into translational motion and, along the axial direction, the other one of the planetary shaft and the solar shaft due to the planetary motion of the planetary shaft. The planetary shaft includes a first planetary gear that forms a part of a first gear train and a second gear that forms a part of a second gear train. The planetary shaft is formed to allow relative rotation between the first planetary gear and the second planetary gear.
Brief description of drawings
Fig. 1 is a perspective view illustrating a conversion mechanism in a mechanism for converting a rotational motion into a linear motion according to the first embodiment of the present invention;
FIG. 2 is a perspective view illustrating the internal structure of the conversion mechanism of FIG. 1;
FIG. 3(A) is a sectional view illustrating the crown shaft of the conversion mechanism of FIG. 1;
FIG. 3(B) is a sectional view illustrating a state in which the crown shaft portion of FIG. 1 is disassembled; FIG.
FIG. 4(A) is a front view illustrating the sun shaft of the conversion mechanism of FIG. 1;
FIG. 4(B) is a front view illustrating a state in which the solar shaft portion of FIG. 4(A) is disassembled;
FIG. 5(A) is a front view illustrating the planetary shaft of the conversion mechanism of FIG. 1;
FIG. 5(B) is a front view illustrating a state in which the part of FIG. 5(A) is disassembled;
FIG. 5(C) is a sectional view taken along the centerline of the rear planetary gear of FIG. 5(A);
FIG. 6 is a sectional view taken along the centerline of the conversion mechanism of FIG. 1;
FIG. 7 is a sectional view along line 7-7 of FIG. 6, illustrating the conversion mechanism of FIG. 1;
FIG. 8 is a sectional view taken along line 8-8 of FIG. 6, illustrating the conversion mechanism of FIG. 1; And
FIG. 9 is a sectional view taken along line 9-9 of FIG. 6, illustrating the conversion mechanism of FIG. 1.
Best Mode for Carrying Out the Invention
Next, the first embodiment of the present invention will be described with reference to FIGS. 1 to 9. Hereinafter, the configuration of the rotational/translational motion conversion mechanism 1 according to the first embodiment, the operating method of the conversion mechanism 1, and the operating principle of the conversion mechanism 1 will be described in this order.
The conversion mechanism 1 is formed by a combination of the crown shaft 2, which has a space extending therein in the axial direction, the sun shaft, which is located inside the crown shaft 2, and the planetary shafts 4, which are located around the sun shaft 3. The crown shaft 2 and the sun shaft 3 are located in a state in which the center lines are aligned or substantially aligned with each other. The sun shaft 3 and the planetary shafts 4 are arranged in a state in which the center lines are parallel or substantially parallel to each other. In addition, the planetary shafts 4 are located around the solar shaft 3 at equal intervals.
In the first embodiment, a position in which the center lines of the components of the conversion mechanism 1 are aligned or substantially aligned with the center line of the sun shaft 2 will be indicated as a centered position. In addition, a position in which the center lines of the components are parallel or substantially parallel to the center line of the solar shaft 3 will be indicated as a parallel position. That is, the crown shaft 2 is held in a centered position. In addition, the planetary shafts 4 are held in a parallel position.
In the conversion mechanism 1, threaded portions and a gear provided on the crown shaft 2 mesh with a threaded portion and a gear provided on each of the planetary shafts 4, so that force is transmitted from one component to another between the crown shaft 2 and the planetary shafts 4. In addition, , a threaded portion and a gear provided on the sun shaft 3 engage with a threaded portion and a gear provided on each of the planetary shafts 4, so that a force is transmitted from one component to another between the sun shaft 3 and the planetary shafts 4.
The conversion mechanism 1 operates as described below based on a combination of such components. When one of the components including the crown shaft 2 and the sun shaft 3 is rotated using the center line of the crown shaft 2 (solar shaft 3) as the axis of rotation, the planetary shafts 4 perform planetary motion around the sun shaft 3 due to the force transmitted from one from components. Accordingly, due to the force transmitted from the planetary shafts to the crown shaft 2 and the solar shaft 3, the crown shaft 2 and the solar shaft 3 move relative to the planetary shafts 4 parallel to the center line of the crown shaft 2 (solar shaft 3).
Thus, the conversion mechanism 1 converts the rotational movement of one of the crown shaft and the sun shaft 3 into the translational movement of the other one of the crown shaft 2 and the sun shaft 3. In the first embodiment, the direction in which the sun shaft 3 is pushed out of the crown shaft 2 along the axial direction sun shaft 3 is indicated as the forward direction FR, and the direction in which the sun shaft 3 extends into the crown shaft 2 is indicated as the rear direction RR. Moreover, when the set position of the conversion mechanism 1 is taken as the reference point, the region in the forward direction FR from the reference position is specified as the front side, and the region in the rear direction RR from the reference position is specified as the rear side.
The front race 51 and the rear race 52, which support the sun shaft 3, are attached to the crown shaft 2. The crown shaft 2, the front race 51 and the rear race 52 move as a single piece. At the crown shaft 2, the open section of the front side is closed by the front race 51. In addition, the open section of the rear side is closed by the rear race 52.
The sun shaft 3 is supported by a bearing 51A of the front race 51 and a bearing 52A of the rear race 52. The planetary shafts 4 are supported neither by the front race 51 nor by the rear race 52. That is, in the conversion mechanism 1, while the radial position of the sun shaft 3 is limited by the engagement of the threaded sections and gears, the front race 51 and the rear race 52, the radial position of the planetary shafts 4 is limited only by the engagement of the threaded sections and gears.
The conversion mechanism 1 adopts the following configuration to lubricate the inside of the crown shaft 2 (the locations at which the threaded portions and gears of the crown shaft 2, the sun shaft 3, and the planetary shafts 4 engage with each other) properly. Lubrication holes 51H for supplying lubricant to the crown shaft 2 are formed in the front race 51. In addition, an O-ring 53 for sealing the inside of the crown shaft 2 is installed on each of the front race 51 and the rear race 52. The front race 51 and the rear race 52 correspond to bearing members .
The configuration of the crown shaft 2 will be described with reference to FIG. 3. The ring shaft 2 is formed by a combination of the ring shaft main body 21 (ring shaft main body), the front ring gear 22 (the first ring gear) and the rear ring gear 23 (the second ring gear). In the crown shaft 2, the center line (axis) of the crown shaft main body 21 corresponds to the center line (axis) of the crown shaft 2. Therefore, when the center line of the crown shaft main body 21 is aligned or substantially aligned with the center line of the sun shaft 3, the crown shaft 2 is in a centered position. The front ring gear 22 and the rear ring gear each correspond to a ring gear with internal teeth.
The ring shaft main body 21 includes a main body threaded portion 21A that is provided with an inner threaded portion 24 formed on the inner circumferential surface, a main body gear portion 21B on which the front ring gear is mounted, and a main body gear portion 21C on which the front ring gear is mounted. rear ring gear 23.
The front ring gear 22 is formed as an internal helical gear separately from the main body 21 of the ring shaft. In addition, the front ring gear 22 is configured so that its center line is aligned with the center line of the ring shaft main body 21 when mounted on the ring shaft main body 21. As for the method of installing the front ring gear 22 into the ring shaft main body 21, the front ring gear 22 is press-fitted to the ring shaft main body 21 in the first embodiment. The front ring gear 22 may be attached to the ring shaft main body 21 in a manner other than a press fit.
The rear ring gear 23 is formed as an internal helical gear separately from the main body 21 of the ring shaft. In addition, the rear ring gear 23 is formed such that its center line is aligned with the center line of the ring shaft main body 21 when mounted on the ring shaft main body 21. As for the method of installing the rear ring gear 23 into the ring shaft main body 21, the rear ring gear 23 is press-fitted to the ring shaft main body 21 in the first embodiment. The rear ring gear 23 may be attached to the ring shaft main body 21 in a manner other than a press fit.
In the ring shaft 2, the front ring gear 22 and the rear ring gear 23 are formed as gears having the same shapes. That is, the specifications (such as the reference pitch diameter and the number of teeth) of the front ring gear 22 and the rear ring gear 23 are set to the same values.
The sun shaft 3 is formed by the combination of the sun shaft main body 31 (solar shaft main body) and the rear sun gear 33. For the sun shaft 3, the center line (axis) of the sun shaft main body 31 corresponds to the center line (axis) of the sun shaft 3.
The sun shaft main body 31 is formed by a main body threaded portion 31A, which has an outer threaded portion 34 formed on its outer circumferential surface, by a main body gear portion 31B on which a front sun gear 32 (first sun gear) serving as a gear is formed. external gearing with the helical tooth, and the main body gear portion 31C on which the rear sun gear (second sun gear) is mounted. The front sun gear 32 and the rear sun gear each correspond to a sun gear with external gear teeth.
The rear sun gear 33 is formed as an external helical gear gear separately from the sun shaft main body 31 . In addition, the rear sun gear 33 is formed such that its center line is aligned with the center line of the sun shaft main body 31 when mounted on the sun shaft main body 31 . As for the method of installing the rear sun gear 33 on the sun shaft main body 31, the rear sun gear 33 is attached to the sun shaft main body 31 by a press fit in the first embodiment. The rear sun gear 33 may be attached to the sun shaft main body 31 in a manner other than a press fit.
On the sun shaft 3, the front sun gear 32 and the rear sun gear 33 are formed as gears having the same shape. That is, the specifications (such as the reference pitch diameter and the number of teeth) of the front sun gear 32 and the rear sun gear 33 are set to the same values.
The configuration of the planetary shafts 4 will be described with reference to FIG. 5. Each planetary shaft 4 is formed by a combination of a planetary shaft main body 41 (planetary shaft main body) and a rear planetary gear 43. For the planetary shaft 4, the center line (axis) of the planetary shaft main body 41 corresponds to the center line (axis) of the planetary shaft 4. Therefore, when the center line of the planetary shaft main body 41 is parallel or substantially parallel to the center line of the sun shaft 3, the planetary shaft 4 is in a parallel position.
The planetary shaft main body 41 is formed by a main body threaded portion 41A, which is provided with an outer threaded portion 44 formed on its outer circumferential surface, a main body gear portion 41B on which a front planetary gear 42 (the first planetary gear) serving as a gear is formed external gearing with an oblique tooth, a rear shaft 41R on which the rear planetary gear 43 (second planetary gear) is mounted, and a front shaft 41F which is inserted into the mandrel during the assembly sequence of the conversion mechanism 1. In addition, the front planetary gear 42 and the rear planetary gear 43 each correspond to an external gear planetary gear.
The rear planetary gear 43 is formed as an external helical gear separately from the planetary shaft main body 41 . In addition, by inserting the rear shaft 41R of the planetary shaft main body 41 into the bearing hole 43H, the rear planetary gear 43 is mounted on the planetary shaft main body 41. In addition, the rear planetary gear 43 is formed such that its center line is aligned with the center line of the planetary shaft main body 41 when mounted on the planetary shaft main body 41.
As for the method of installing the rear planetary gear 43 on the planetary shaft main body 41, a loose fit is adopted in the first embodiment, so that the rear planetary gear is rotatable relative to the planetary shaft main body 41. As for the installation method for allowing the planetary shaft main body 41 and the rear planetary gear 43 to rotate relative to each other, an installation method other than free-fitting may be used.
On the planetary shaft 4, the front planetary gear 42 and the rear planetary gear 43 are formed as gears having the same shape. That is, the specifications (such as the reference pitch diameter and the number of teeth) of the front planetary gear 42 and the rear planetary gear 43 are set to the same values.
With reference to FIGS. 6 to 9, the relationship between the components of the conversion mechanism 1 will be described. In this specification, a conversion mechanism 1 equipped with nine planetary shafts 4 is given as an example, although the number of planetary shafts 4 can be changed as required.
In the conversion mechanism 1, the operation of the components is enabled or limited as mentioned below in (a)-(c).
(a) As for the ring shaft 2, the ring shaft main body 21, the front ring gear 22 and the rear ring gear 23 are prevented from rotating relative to each other. In addition, the crown shaft main body 21, the front race 51 and the rear race 52 are prevented from rotating relative to each other.
(b) As for the sun shaft 3, the sun shaft main body 31 and the rear sun gear 33 are prevented from rotating relative to each other.
(c) Regarding the planetary shaft 4, the planetary shaft main body 41 and the rear planetary gear 43 are allowed to rotate relative to each other.
In the conversion mechanism 1, the sun shaft 3 and the planetary shafts 4, force is transmitted between the components as described below due to the meshing of the threaded portions and the gears of the ring shaft 2.
With respect to the crown shaft 2 and the planetary shafts 4, the inner threaded portion 24 of the crown shaft main body 21 and the outer threaded portion 44 of each planetary shaft main body 41 are engaged with each other. In addition, the front ring gear 22 of the ring shaft main body 21 and the front planetary gear 42 of each planetary shaft main body 41 are meshed with each other. In addition, the rear ring gear 23 of the ring shaft main body 21 and the rear planetary gear 43 of each planetary shaft main body 41 are meshed with each other.
Thus, when rotational motion is applied to the ring shaft 2 or the planetary shafts 4, a force is transmitted to the other one of the ring shaft 2 and the planetary shafts 4 through the engagement of the inner threaded portion 24 and the outer threaded portions 44, the engagement of the front ring gear 22 and the front planetary gears 42, engagement of the rear ring gear 23 and the rear planetary gears 43.
At the sun shaft 3 and the planetary shafts 4, the outer threaded portion 34 of the solar shaft main body 31 and the outer threaded portion 44 of each planetary shaft main body 41 engage with each other. In addition, the front sun gear 32 of the sun shaft main body 31 and the front planetary gear 42 of each planetary shaft main body 41 are meshed with each other. In addition, the rear sun gear 33 of the sun shaft main body 31 and the rear planetary gear 43 of each planetary shaft main body 41 are meshed with each other.
Thus, when rotational motion is applied to the sun shaft 3 or the planetary shafts 4, a force is transmitted to the other one of the sun shaft 3 and the planetary shafts 4 through the engagement of the outer threaded portion 34 and the outer threaded portions 44, the engagement of the front sun gear 32 and the front planetary gears 42, meshing the rear sun gear 33 and the rear planetary gears 43.
As described above, the conversion mechanism 1 includes a retardation mechanism formed by the inner threaded portion 24 of the crown shaft 2, the outer threaded portion 24 of the crown shaft 2, the outer threaded portion 34 of the sun shaft 3, and the outer threaded portions 44 of the planetary shafts 4, the retardation mechanism (the first a gear train) formed by the front ring gear 22, the front sun gear 32 and the front planetary gears 42, and a deceleration mechanism (second gear) formed by the rear ring gear 23, the rear sun gear 33 and the rear planetary gears 43.
In the conversion mechanism 1, according to the threads of each threaded portion, the operating mode (motion conversion mode) for converting the rotational motion into a linear motion is determined based on the number and setting method of the number of teeth of each gear. That is, as the motion conversion mode, either the sun shaft movement mode is selected, in which the solar shaft 3 moves translationally due to the rotational movement of the crown shaft, or the annular shaft movement mode, in which the crown shaft 2 moves translationally due to the rotational movement of the solar shaft 3. In the future, it will be a method of operation of the conversion mechanism 1 in each motion conversion mode is described.
(A) When the solar shaft moving mode is applied as the motion conversion mode, the rotational motion is converted to linear motion as described below. When rotational motion is applied to the ring shaft 2, force is transmitted from the crown shaft 2 to the planetary shafts 4 through the engagement of the front ring gear 22 and the front planetary gears 42, the engagement of the rear ring gear 23 and the rear planetary gears 43, the engagement of the internal threaded portion 24 and the external threads sections 44. Thus, the planetary shafts 4 rotate, with their central axes serving as centers of rotation, about the solar shaft 3 and rotate around the solar shaft 3, with the central axis of the solar shaft 3 serving as the center of rotation. Accompanying the planetary movement of the planetary shafts 4, the force is transmitted from the planetary shafts 4 to the sun shaft 3 through the engagement of the front planetary gears 42 and the front sun gear 32, the engagement of the rear planetary gears 43 and the rear sun gear 33, the engagement of the external threaded sections 44 and the external threaded section 34 Accordingly, the solar shaft 3 is displaced in the axial direction.
(B) When the ring shaft moving mode is applied as the motion conversion mode, the rotational motion is converted to linear motion as described below. When rotational motion is applied to the sun shaft 3, a force is transmitted from the sun shaft 3 to the planetary shafts 4 through the engagement of the front sun gear 32 and the front planetary gears 42, the engagement of the rear sun gear 33 and the rear planetary gears 43, the engagement of the male threaded portion 34 and the male threads. sections 44. Thus, the planetary shafts 4 rotate, with their central axes serving as centers of rotation, about the solar shaft 3 and rotate around the solar shaft 3, with the central axis of the solar shaft 3 serving as the center of rotation. Accompanying the planetary movement of the planetary shafts 4, the force is transmitted from the planetary shafts 4 to the crown shaft 2 through the engagement of the front planetary gears 42 and the front ring gear 22, the engagement of the rear planetary gears 43 and the rear crown gear 23, the engagement of the external threaded sections 44 and the internal threaded section 24 Accordingly, the crown shaft 2 is displaced in the axial direction.
The operating principle of the conversion mechanism 1 will now be described. Subsequently, the reference pitch diameter and the number of teeth of the gears of the crown shaft 2, sun shaft 3 and planetary shafts 4 are expressed as shown in (A) to (F) below. In addition, the reference pitch diameter and the number of threads of the threaded portions of the crown shaft 2, sun shaft 3 and planetary shafts 4 are expressed as shown in the following (a) to (f).
“Reference pitch diameter and number of gear teeth”
(A) Effective ring gear diameter, DGr: reference pitch diameter of ring gears 22, 23.
(B) Effective sun gear diameter, DGs: reference pitch diameter of sun gears 32, 33.
(C) Effective diameter of planetary gear, DGp: reference pitch diameter of planetary gears 42, 43.
(D) Number of ring gear teeth, ZGr: number of ring gear teeth 22, 23.
(E) Number of sun gear teeth, ZGs: number of sun gear teeth 32, 33.
(F) Number of teeth of planetary gear, ZGp: number of teeth of planetary gears 42, 43.
“Reference pitch diameter and number of thread turns of threaded sections”
(a) Effective diameter of the annular threaded portion, DSr: reference pitch diameter of the internal threaded portion 24 of the crown shaft 2.
(b) Effective diameter of the solar threaded section, DSs: reference pitch diameter of the external threaded section 34 of the sun shaft 3.
(c) Effective diameter of the planetary threaded section DSp: the reference pitch diameter of the outer threaded sections 44 of the planetary shafts 4.
(d) Number of threads of the annular threaded section, ZSr: number of threads of the internal threaded section 24 of the crown shaft 2.
(e) Number of threads of the solar threaded section, ZSs: number of threads of the external threaded section 34 of the sun shaft 3.
(f) Number of threads of the planetary threaded section, ZSp: number of threads of the external threaded sections of 44 planetary shafts 4.
In the conversion mechanism 1, when the solar shaft 3 is displaced relative to the planetary shafts 4 in the axial direction, the ratio of the number of threads of the solar threaded section ZSs to the number of threads of the planetary threaded section ZSp (the ratio ZSA of the number of threads of the solar to planetary threads) differs from the ratio of the number of solar teeth gears ZGs to the number of teeth of the planetary gear ZGp (ratio ZGA of the number of teeth of the solar to planetary ones). The ratio of the number of thread turns of the annular threaded section ZSr to the number of thread turns of the planetary threaded section ZSp (ratio ZSB of the number of thread turns of the annular to planetary threads) is equal to the ratio of the number of teeth of the ring gear ZGr to the number of teeth of the planetary gear ZGp (ratio ZGB of the number of teeth of the ring to planetary). That is, the following [expression 11] and [expression 12] are satisfied.
In the conversion mechanism 1, when the crown shaft 2 is displaced relative to the planetary shafts 4 in the axial direction, the ratio of the number of threads of the annular threaded section ZSr to the number of threads of the planetary threaded section ZSp (the ratio ZSB of the number of threads of the solar to planetary threads) differs from the ratio of the number of teeth of the annular gear ZGr to the number of teeth of the planetary gear ZGp (ratio ZGB of the number of teeth of ring to planetary). The ratio of the number of thread turns of the solar threaded section ZSs to the number of thread turns of the planetary threaded section ZSp (ratio ZSA of the number of thread turns of solar to planetary) is equal to the ratio of the number of teeth of the sun gear ZGs to the number of teeth of the planetary gear ZGp (ratio ZGA of the number of teeth of solar to planetary). That is, the following [expression 21] and [expression 22] are satisfied.
Here, the retarding mechanism formed by the inner threaded portion 24, the outer threaded portion 34, and the outer threaded portions 44 will be referred to as the first planetary retarding mechanism, and the retarding mechanism formed by the ring gears 22, 23, sun gears 32, 33, and planetary gears 42 43 will be indicated as the second planetary deceleration mechanism.
When the sun shaft 3 is displaced relative to the planetary shafts 4 in the axial direction, the solar to planetary thread number ratio ZSA of the first planetary retardation mechanism is different from the solar to planetary tooth number ratio ZGA of the second planetary deceleration mechanism, as shown by [Expression 11] and [Expression 12] . When the crown shaft 2 is displaced relative to the planetary shafts 4 in a direction along the axial direction of the crown shaft 2, the ratio ZSB of the numbers of ring to planetary threads of the first planetary deceleration mechanism is different from the ratio ZGB of the numbers of ring to planetary teeth of the second planetary deceleration mechanism, as shown by [Equation 21] and [expression 22].
As a result, in any of the above cases, a force acts between the first planetary deceleration mechanism and the second planetary deceleration mechanism to generate a difference in the rotation angle by an amount corresponding to the difference between the thread number ratio and the tooth number ratio. However, since the threaded portions of the first planetary retarder and the gears of the second planetary retarder are formed as an integral part, a difference in rotation angle cannot be generated between the first planetary retarder and the second planetary retarder. Thus, the sun shaft 3 or the crown shaft 2 moves relative to the planetary shafts 4 in the axial direction to absorb the difference in the rotation angle. At this time, the component that is displaced in the axial direction (sun shaft 3 or crown shaft 2) is determined as described below.
(a) When the ratio of the number of threads of the sun threaded section ZSs to the number of threads of the planetary threaded section ZSp is different from the ratio of the number of sun gear teeth ZGs to the number of teeth of the planetary gear ZGp, the sun shaft 3 is displaced relative to the planetary shafts 4 in the axial direction.
(b) When the ratio of the number of threads of the annular threaded portion ZSr to the number of threads of the planetary threaded portion ZSp is different from the ratio of the number of teeth of the ring gear ZGr to the number of teeth of the planetary gear ZGp, the ring shaft 2 is displaced relative to the planetary shafts 4 in the axial direction.
Thus, the conversion mechanism 1 uses the difference in rotation angle generated according to the difference in the ratio of the number of threads and the ratio of the number of teeth of the sun shaft or crown shaft with respect to the planetary shafts 4 between the two kinds of planetary retardation mechanisms, and obtains an axial displacement corresponding to the difference in the angle of rotation, along the threaded sections, thereby converting rotational motion into translational motion.
In the conversion mechanism 1, by setting at least one of the “number of effective teeth” and the “number of effective threads” described below to a value other than “0” for the crown shaft 2 or the sun shaft 3, a translational the movement of the sun shaft 3, based on the relationship between the ratio ZSA of the numbers of solar to planetary threads and the ratio ZGA of the numbers of solar to planetary teeth, or the translational movement of the crown shaft 2, based on the relationship between the ratio ZSB of the numbers of ring to planetary threads and the ratio ZGB of the numbers of teeth annular to planetary.
“Setting the number of active teeth”
In a typical planetary retarding mechanism (planetary gear type retarding mechanism) formed by the ring gear, sun gear and planetary gears, that is, in a planetary gear type retarding mechanism that decelerates the rotation due to the meshing of the gears, the relationship represented by the following with [ expressions 31] to [expression 33]. [Expression 31] represents the relationship established between the reference pitch diameters of the ring gear, sun gear and planetary gears. [Expression 32] represents the relationship established between the numbers of teeth of the ring gear, sun gear and planetary gears. [Expression 33] represents the relationship established between the reference pitch diameters and the number of teeth of the ring gear, sun gear and planetary gear.
| DAr=DAs+2×DAp | [expression 31] |
| ZAr=ZAs+2×ZAp | [expression 32] |
| DAr/ZAr=DAs/ZAs=DAp/ZAp | [expression 33] |
DAr: ring gear reference pitch diameter
DAs: sun gear reference pitch diameter
DAp: Planetary gear reference pitch diameter
ZAr: number of ring gear teeth
ZAs: number of sun gear teeth
ZAp: number of planetary gear teeth
In the conversion mechanism 1 of the first embodiment, provided that the second planetary deceleration mechanism, that is, the deceleration mechanism formed by the ring gears 22, 23, sun gears 32, 33 and planetary gears 42, 43, has the same configuration as the above-mentioned mechanism planetary gear type deceleration, the relationship established between the reference pitch diameters of the gears, the relationship established between the number of gear teeth, and the relationship established between the reference pitch diameter and the number of gear teeth are represented by the following from [Expression 41] to [Expression 43].
| DGr=DGs+2×DGp | [expression 41] |
| ZGr=ZGs+2×ZGp | [expression 42] |
| DGr/ZGr=DGs/ZGs=DGp/ZGp | [expression 43] |
In the case where the number of teeth of the ring gears 22, 23, sun gears 32, 33 and planetary gears 42, 43, when the relationships presented in [Expression 41] to [Expression 43] are satisfied, is specified as the reference number of teeth, "number of effective teeth » is expressed as the difference between the number of teeth and the reference number of teeth of each gear. In the conversion mechanism 1, by setting the number of effective teeth of one of the crown shaft 2 and the sun shaft 3 to a value other than “0”, the crown shaft 2 or the sun shaft 3 can move forward. That is, when the reference number of teeth of the ring gears 22, 23 is represented by the reference number of ring teeth, ZGR, and the reference number of teeth of the sun gears 32, 33 is represented by the reference number of sun teeth, ZGS, by setting the number of teeth of the ring gears 22, 23 or the sun gears 32 , 33, from the condition that one of the following [Expressions 44] and [Expressions 45] is satisfied, the crown shaft 2 or the sun shaft 3 can move translationally.
When [Expression 44] is satisfied, the crown shaft 2 moves forward. When [Expression 45] is satisfied, the sun shaft 3 moves forward. A separate setting method is shown in “A separate example of the method for setting the number of teeth and the number of threads.”
“Setting the number of effective thread turns”
In a planetary retarding mechanism (planetary threaded type retarding mechanism), which is identical to the above-mentioned planetary gear type retarding mechanism and is formed by an annular threaded portion corresponding to the ring gear, a sun threaded portion corresponding to the sun gear, and planetary threaded portions corresponding to the planetary gears , that is, in a planetary threaded type retarding mechanism that decelerates rotation like the above-mentioned planetary type retarding mechanism only due to the meshing of threaded portions, the relationships represented by the following from [Expression 51] to [Expression 53] are satisfied. [Expression 51] represents the relationship established between the reference pitch diameters of the annular threaded portion, the sun threaded portion, and the planetary threaded portions. [Expression 52] represents the relationship established between the number of teeth of the annular threaded portion, the sun threaded portion, and the planetary threaded portions. [Expression 53] represents the relationship established between the reference pitch diameter and the number of teeth of the annular threaded portion, the sun threaded portion, and the planetary threaded portions.
| DBr=DBs+2×DBp | [expression 51] |
| ZBr=ZBs+2×ZBp | [expression 52] |
| DBr/ZBr=DBs/ZBs=DBp/ZBp | [expression 53] |
DBr: reference pitch diameter of the annular threaded section
DBs: reference pitch diameter of solar threaded section
DBp: reference pitch diameter of planetary threaded section
ZBr: number of threads of the annular threaded section
ZBs: number of threads of the solar threaded section
ZBp: number of threads of the planetary threaded section
In the conversion mechanism 1 according to the first embodiment, provided that the first planetary deceleration mechanism has the same configuration as the above-mentioned planetary threaded type deceleration mechanism, the ratio established between the reference pitch diameters of the threaded portions, the ratio established between the number of threads of the threaded portions sections, and the relationship established between the reference pitch diameters and the number of thread turns of the threaded sections are expressed as follows from [expression 61] to [expression 63].
| DGr=DGs+2×DGp | [expression 61] |
| ZGr=ZGs+2×ZGp | [expression 62] |
| DGr/ZGr=DGs/ZGs=DGp/ZGp | [expression 63] |
In the case where the number of thread turns of the inner threaded section 24 of the crown shaft 2, the outer threaded section 34 of the sun shaft 3 and the outer threaded sections 44 of the planetary shafts 4, when the ratios of the above from [Expression 61] to [Expression 63] are satisfied, is indicated as a reference number threads, the “number of effective threads” is represented as the difference between the number of threads of each threaded section and the reference number of threads. In the conversion mechanism 1, by setting the number of effective threads of one of the crown shaft 2 and the sun shaft 3 to a value other than "0", the crown shaft 2 or the sun shaft 3 moves forward. That is, when the reference number of threads of the inner threaded portion 24 of the sun shaft 2 is represented by the reference number of annular threads ZSR, and the reference number of threads of the outer threaded portion 34 of the sun shaft 3 is represented by the reference number of sun threads ZSS, the crown shaft 2 or the sun shaft 3 advances by setting the number of threads such that one of the following [Expression 64] and [Expression 65] is satisfied.
When [Expression 64] is satisfied, the crown shaft 2 moves forward. When [Expression 65] is satisfied, the sun shaft 3 moves forward. A separate setting method is shown in “A separate example of the method for setting the number of teeth and the number of threads.”
In a typical planetary gear type retarding mechanism, the number of planetary gears is a divisor of the sum of the number of sun gear teeth and the number of ring gear teeth. Thus, the number of planetary shafts 4 (planetary number Np) in the conversion mechanism 1 is a common divisor of the “divisors of the sum of the number of thread turns of the sun threaded section ZSs and the number of thread turns of the annular threaded section ZSr” and “divisors of the sum of the number of sun gear teeth ZGs and the number of ring gear teeth ZGr".
In the conversion mechanism 1, the threaded portions and gears are simultaneously meshed by setting the number of ring gear teeth ZGr, the number of sun gear teeth ZGs, and the number of planet gear teeth ZGp (total ratio of the number of teeth ZGT) to the ratio of the effective diameter of the ring gear DGr, the effective diameter of the sun gear DGs and the effective diameter of the planetary gear DGp (total effective diameter ratio, ZST). That is, by setting the number of gear teeth and the number of thread turns of the threaded sections so that the relationship of the following [Expression 71] is satisfied, the threaded sections and gears are meshed simultaneously.
| ZGr:ZGs:ZGp=DGr:DGs:DGp | [expression 71] |
However, in this case, since the rotation phases of the planetary shafts 4 are the same, the beginning and end of the meshing of the planetary gears 42, 43, ring gears 22, 23 and sun gears 32, 33, accompanying the rotation, coincide. This causes torque pulsations due to gear meshing, which can increase operating noise and reduce gear life.
That is, in the conversion mechanism 1, the total tooth number ratio ZGT and the total effective diameter ratio ZST are set to different values within a range in which the following conditions (A) to (C) are satisfied. The total tooth number ratio ZGT and the total effective diameter ratio ZST can be set to different values within a range in which at least one of the conditions (A) to (C) is satisfied.
(A) In the case where the number of sun gear teeth, ZGs, if the relationship in [Equation 71] is satisfied, is specified as the reference number of sun teeth ZGSD, the actual number of sun gear teeth ZGs is different from the reference number of sun teeth ZGSD.
(B) In the case where the number of ring gear teeth, ZGr, if the relationship in [Expression 71] is satisfied, is specified as the reference number of ring teeth ZGRD, the actual number of ring gear teeth ZGr is different from the reference number of ring teeth ZGRD.
(C) The planetary number Np is different from the planetary gear tooth number divisor ZGp, that is, the planetary number Np and the planetary gear tooth number ZGp do not have a divisor other than “1”.
Since this achieves an operating method in which the threaded portions and gears mesh simultaneously, and an operating method in which the rotation phases of the planetary shafts 4 are different from each other, torque ripple caused by the gear meshing is suppressed.
The main points representing the technical conditions of the conversion mechanism 1 are given in the following points (A)-(I), which include the number of effective threads and the number of effective teeth.
(B) Solar/planetary thread ratio
(E) Gear tooth ratio
(F) Ratio of effective diameters of threaded sections
(G) Effective gear diameter ratio
(H) Number of effective threads
(I) Number of active teeth
The details of the above points will be described below.
"Motion conversion mode" in (A) represents an operating mode for converting rotational motion into linear motion. That is, when the sun shaft 3 moves forward through the rotational movement of the crown shaft 2, the motion conversion mode is in the “sun shaft movement mode.” When the crown shaft 2 advances through the rotational motion of the sun shaft 3, the motion conversion mode is in the “ring shaft motion mode.”
The "ratio of thread numbers of threaded sections" in (D) represents the ratio of the number of threads of the solar threaded section ZSs, the number of threads of the planetary threaded section ZSp, and the number of threads of the annular threaded section ZSr. That is, the “ratio of the number of thread turns of threaded sections” is “ZSs:ZSp:ZSr”.
The “gear tooth ratio” of (E) represents the ratio of the sun gear tooth number ZGs, the planetary gear tooth number ZGp, and the ring gear tooth number ZGr. That is, the ratio of the number of gear teeth is ZGs:ZGp:ZGr.
The "effective diameter ratio of threaded portions" of (F) represents the ratio of the effective diameter of the solar threaded portion DSs, the effective diameter of the planetary threaded portion DSp, and the effective diameter of the annular threaded portion DSr. That is, the ratio of the effective diameters of the threaded sections is DSs:DSp:DSr.
The "effective gear diameter ratio" of (G) represents the ratio of the effective diameter of the sun gear DGs, the effective diameter of the planetary gear DGp and the effective diameter of the ring gear DGr. That is, the ratio of the effective diameters of the gears is DGs:DGp:DGr.
“The number of effective threads” according to (H) represents the difference between the actual number of threads of a threaded section (the number of threads according to (D)) and the reference number of threads. That is, when the motion conversion mode is in the sun shaft motion mode, the number of effective threads is a value obtained by subtracting the reference number of solar threads ZSS from the number of threads of the solar threaded section ZSs in (D). When the motion conversion mode is in the annular shaft moving mode, the number of effective threads is a value obtained by subtracting the reference number of annular threads ZSR from the thread number of the annular threaded portion ZSr in (D).
The "number of effective teeth" in (I) represents the difference between the actual number of teeth of the gear (number of teeth in (E)) and the reference number of teeth. That is, when the motion conversion mode is in the sun shaft moving mode, the number of effective teeth is a value obtained by subtracting the reference number of sun teeth ZGS from the number of sun gear teeth ZGs in (E). In addition, when the motion conversion mode is in the ring shaft moving mode, the number of effective teeth is a value obtained by subtracting the reference number of ring teeth ZGR from the number of ring gear teeth ZGr in (E).
A separate installation method for the above items will now be illustrated.
Example 1 installation
(C) Number of planetary shafts: "4"
(D) Ratio of thread numbers of threaded sections: “3:1:5”
(E) Gear tooth ratio: “31:9:45”
(G) Effective gear diameter ratio: “3.44:1:5”
(H) Number of effective threads: “0”
(I) Number of active teeth: "4"
Installation example 2
(A) Motion conversion mode: “solar shaft moving mode”
(B) Solar/planetary threaded section ratio: “reverse direction”
(D) Ratio of thread numbers of threaded sections: “4:1:5”
(F) Ratio of effective diameters of threaded sections: “3:1:5”
(G) Effective gear diameter ratio: “3.1:1:5”
Installation Example 3
(A) Motion conversion mode: “solar shaft moving mode”
(B) Solar/planetary threaded section ratio: "forward direction"
(C) Number of planetary shafts: "9"
(D) Ratio of thread numbers of threaded sections: “-5:1:5”
(E) Gear tooth ratio: “31:10:50”
(F) Ratio of effective diameters of threaded sections: “3:1:5”
(G) Effective gear diameter ratio: “3.1:1:5”
(H) Number of effective threads: “-8”
(I) Number of active teeth: "1"
Installation Example 4
(A) Motion conversion mode: “solar shaft moving mode”
(B) Solar/planetary threaded section ratio: “reverse direction”
(C) Number of planetary shafts: "11"
(D) Ratio of thread numbers of threaded sections: “5:1:6”
(E) Gear tooth ratio: “39:10:60”
(F) Ratio of effective diameters of threaded sections: “4:1:6”
(G) Effective gear diameter ratio: “3.9:1:6”
(H) Number of effective threads: "1"
(I) Number of active teeth: "-1"
Installation Example 5
(A) Motion conversion mode: “solar shaft moving mode”
(B) Solar/planetary threaded section ratio: “reverse direction”
(C) Number of planetary shafts: "7"
(D) Ratio of thread numbers of threaded sections: “2:1:5”
(E) Gear tooth ratio: “25:9:45”
(F) Ratio of effective diameters of threaded sections: “3:1:5”
(G) Effective gear diameter ratio: “2.78:1:5”
(H) Number of effective threads: “-1”
(I) Number of active teeth: "-2"
Installation example 6
(A) Motion conversion mode: “solar shaft moving mode”
(B) Solar/planetary threaded section ratio: “reverse direction”
(C) Number of planetary shafts: "5"
(D) Ratio of thread numbers of threaded sections: “11:2:14”
(E) Gear tooth ratio: “58:11:77”
(F) Effective diameter ratio of threaded sections: “6:1:8”
(G) Effective gear diameter ratio: “5.8:1.1:7.7”
(H) Number of effective threads: "1"
(I) Number of active teeth: "3"
Installation example 7
(B) Solar/planetary threaded section ratio: “reverse direction”
(C) Number of planetary shafts: "9"
(E) Gear tooth ratio: “30:10:51”
(F) Ratio of effective diameters of threaded sections: “3:1:5”
(G) Effective gear diameter ratio: “3:1:5.1”
(H) Number of effective threads: "1"
(I) Number of active teeth: "1"
As described above, the first embodiment has the following advantages.
(1) The operations and advantages of the conversion mechanism 1 according to the first embodiment will be further described based on comparison with a rotational/translational motion conversion mechanism (basic motion conversion mechanism) equipped with planetary shafts in which the front planetary gear and the rear planetary gear are formed as an integral part with the main shaft housing.
In the above basic motion conversion mechanism, if there is a rotation phase shift between the front ring gear and the rear ring gear, planetary shafts are arranged between the ring shaft and the sun shaft in an inclined state with respect to the central axis of the sun shaft (ring shaft) in accordance with the phase shift. Thus, the engagement of the threaded sections between the crown shaft, the sun shaft and the planetary shafts 4 becomes uneven, which locally increases the pressure between the threaded sections and the gears. As a result, localized wear is caused, thereby reducing the service life of the conversion mechanism and reducing the conversion efficiency from rotational motion to linear motion due to increased wear.
In contrast, in the conversion mechanism 1 according to the first embodiment, the planetary shafts 4 are formed to allow the front planetary gear 42 and the rear planetary gear 43 to rotate relative to each other. Thus, the rotational phase shift between the front ring gear 22 and the rear ring gear 23 is absorbed. That is, when a rotational phase shift is caused between the front ring gear 22 and the rear ring gear 23, the rotational phase shift is absorbed by rotating each rear planetary gear 43 relatively associatively associated shaft main body 41 (relative rotation of the front planetary gear 42 and the rear planetary gear 43). This suppresses the tilt of the planetary shafts 4 caused by the misalignment between the rotation phase of the front ring gear 22 and the rotation phase of the rear ring gear 23. Thus, uniform engagement of the threaded portions and uniform engagement of the gears between the ring shaft 2, sun shaft 3 and planetary shafts 4 are achieved. How result, the service life of the conversion mechanism 1 and the efficiency of motion conversion are improved.
(2) To suppress the tilt of the planetary shafts 4, for example, the conversion mechanism 1 is manufactured as described below. That is, in the manufacturing process of the conversion mechanism 1, the offset between the rotation phase of the front ring gear 22 and the rotation phase of the rear ring gear 23 is reduced by combining components along with adjusting the rotation phases of the front ring gear and the rear ring gear 23. However, in this case, since the rotation phases of the gears must strictly regulated, productivity is reduced. Moreover, the phase shift could not be sufficiently reduced despite the fact that the rotation phases of the gears are adjusted. Therefore, this countermeasure is not preferred.
In contrast, the conversion mechanism 1 of the first embodiment adopts a configuration in which the rotational phase shift is absorbed due to the relative motion of the front planetary gear 42 and the rear planetary gear 43 as described above. Therefore, performance is improved and the tilt of the planetary shafts 4 is suppressed more suitably.
(3) In each of the planetary shafts 4 of the conversion mechanism of the first embodiment, the front planetary gear 42 and the outer threaded portion 44 are formed as an integral part with the shaft main body 41. As a result, during the production of the planetary shafts 4, the front planetary gear 42 and the outer threaded portion 44 can be rolled simultaneously, which improves productivity.
(4) In the conversion mechanism 1 of the first embodiment, the radial position of the sun shaft 3 is limited by the meshing of the threaded portions and the meshing of the gears, the front race 51 and the rear race 52. The radial position of the planetary shafts 4 is limited by the meshing of the threaded portions and the meshing of the gears. As a result, since the conversion mechanism 1 is formed by a minimum number of components for restraining the planetary shafts 4, the planetary shafts 4 are restrained from tilting relative to the axial direction of the sun shaft 3 properly.
(5) In the conversion mechanism 1 of the first embodiment, the front race 51 is provided with oil holes 51H. Thus, since lubricant can be supplied to the meshing portion of the threaded portions and gears through the lubrication holes 51H, the service life of the threaded portions and gears is improved. In addition, since foreign objects in the conversion mechanism 1 are thrown out as lubricant is supplied through the lubrication holes 51H, reduction in conversion efficiency and malfunction caused by foreign objects are suppressed.
(6) In the conversion mechanism 1 of the first embodiment, the total tooth number ratio ZGT and the total effective diameter ratio ZST are set to different values within the range in which conditions (A) to (C) are satisfied. This achieves a method of operation in which the engagement of the threaded sections and the engagement of the gears is achieved simultaneously, and a method of operation in which the rotation phases of the planetary shafts 4 differ from each other. In this way, torque pulsations caused by gear meshing are suppressed. In addition, operating noise is reduced and the durability life is accordingly improved.
The first embodiment may be modified as follows.
As a configuration for allowing the front planetary gear 42 and the rear planetary gear 43 to rotate relative to each other, the first embodiment adopts a configuration in which the main shaft body 41 and the rear planetary gear 43 are formed separately. However, this can be modified as described below. The main shaft body 41, the front planetary gear 42 and the rear planetary gear 43 are formed separately and connected so that these components rotate relative to each other. This allows the front planetary gear 42 and the rear planetary gear 43 to rotate relative to each other.
The conversion mechanism 1 of the first embodiment is a conversion mechanism that operates based on the following operating principles. That is, the rotational motion is converted into a linear motion due to the difference between the rotation angles formed in accordance with the difference between the ratio of the number of teeth and the ratio of the number of threads of the sun shaft 3 or the crown shaft 2 to the planetary shafts 4 in the two types of planetary deceleration mechanisms. In contrast, the conversion mechanism of the embodiment described below is a conversion mechanism that operates based on the following operating principles. The conversion mechanism of the second embodiment is different from the conversion mechanism 1 of the first embodiment because the configuration described below is adopted, but the other configuration is the same as that of the conversion mechanism 1 of the first embodiment.
When the planetary gear type deceleration mechanism is formed by sun gears, due to the rotation direction relationship of the gears, the sun gear tooth inclination line and the planetary gear tooth inclination line are set in opposite directions from each other, and the torsion angles of the gears are set to the same amount. In addition, a gear having a torsion angle that is in the same direction as the planetary gear is used as a ring gear.
Therefore, in order to configure the deceleration mechanism (planetary thread type deceleration mechanism), which is the same as the planetary gear type deceleration mechanism, the meshing of the threaded portions, the initial helix angle of the helix line of the sun threaded portion corresponding to the sun gear of the planetary threaded portion , corresponding to the planetary gear, and the annular threaded portion corresponding to the ring gear are set to the same value, and the sun threaded portion has a threaded portion in the opposite direction. In such a planetary threaded gear deceleration mechanism, neither component is axially displaced relative to the other component. However, provided that such a state where relative movement in the axial direction does not occur is referred to as the reference state, the sun threaded portion or the annular threaded portion may be displaced in the axial direction by changing the advance angle of the sun threaded portion or the annular threaded portion from the reference state along with with the engagement of threaded sections.
In general, for two threaded sections to fully engage, the thread pitches need to be set to the same size. In addition, in the planetary threaded gear type deceleration mechanism, in order to align all the advance angles of the sun threaded portion, the planetary threaded portions and the annular threaded portion, the ratio of the reference pitch diameter of the sun threaded portion, the planetary threaded portions and the annular threaded portion needs to be adjusted to the ratio number of threads of the solar threaded section, planetary threaded sections and annular threaded section.
Therefore, in a planetary threaded gear type deceleration mechanism, the conditions in which none of the components move in the axial direction are the following conditions (1)-(3):
(1) The ratio in which only the solar threaded portion is a reverse thread among the solar threaded portion, the planetary threaded portions and the annular threaded portion.
(2) The thread pitches of the sun threaded portion, planetary threaded portions, and annular threaded portion are the same size.
(3) The ratio of the reference pitch diameter of the solar threaded portion, the planetary threaded portions and the annular threaded portion is the same value as the ratio of the number of thread turns of the solar threaded portion, the planetary threaded portions and the annular threaded portion.
In contrast, when the number of threads of the sun threaded portion or the annular threaded portion increases from the number of threads of the above (2) by an integer number of thread turns, the sun threaded portion or the annular threaded portion moves in an axial direction relative to the other threaded portions. Thus, the second embodiment reflects the above idea in the configuration of the conversion mechanism 1. This allows the conversion mechanism 1 to convert the rotational motion into a linear motion.
When the solar shaft moving mode is applied, the conversion mechanism 1 is configured to satisfy the following conditions (A)-(D). When the ring shaft moving mode is applied, the conversion mechanism 1 is configured to satisfy the following conditions (A) to (C) and (E):
(A) The twisting direction of the outer threaded portion 34 of the sun shaft 3 is opposite to the twisting direction of the outer threaded portions 44 of the planetary shaft 4.
(B) The twisting direction of the inner threaded portion 24 of the crown shaft 2 is the same as the twisting direction of the outer threaded portions 44 of the planetary shaft 4.
(C) The thread pitches of crown shaft 2, sun shaft 3 and planetary shafts 4 are identical.
(D) With regard to the relationship between the reference pitch diameter and the number of threads of the threaded portions of the crown shaft 2, sun shaft 3 and planetary shafts 4, provided that the relationship when none of the crown shaft 2, sun shaft 3 and planetary shafts 4 is subject to relative displacement in the axial direction, is indicated as the reference ratio, the number of threads of the outer threaded portion 34 of the solar shaft 3 is greater or less than the number of threads in the reference ratio by an integer.
(E) With regard to the relationship between the reference pitch diameter and the number of threads of the threaded portions of the crown shaft 2, sun shaft 3 and planetary shafts 4, provided that the relationship when none of the crown shaft 2, sun shaft 3 and planetary shafts 4 is subject to relative displacement in the axial direction, is indicated as the reference ratio, the number of threads of the internal threaded portion 24 of the crown shaft 2 is greater or less than the number of threads in the reference ratio by an integer.
In the conversion mechanism 1, provided that there is no relative displacement in the axial direction between the annular shaft 2, the sun shaft 3 and the planetary shafts 4, the relationship represented by [Expression 81] is established between the reference pitch diameter and the number of threads of the threaded portions.
| DSr:DSs:DSp=ZSr:ZSs:ZSp | [expression 81] |
In the case where the number of thread turns of the inner threaded portion 24 of the crown shaft 2, the outer threaded portion 34 of the sun shaft 3, and the outer threaded portions 44 of the planetary shafts 4, when the ratio of [Expression 81] is satisfied, is assumed to be the “reference number of thread turns,” and the difference between the number of threads of the threaded portions and the reference number of threads is assumed to be the "number of effective threads", the crown shaft 2 or the sun shaft 3 can move forward in the conversion mechanism 1 by setting the "number of effective threads" of one of the crown shaft 2 and the sun shaft 3 to a value other than “0”. That is, when the reference number of threads of the inner threaded portion 24 of the sun shaft 2 is indicated as the reference number of the annular threads ZSR, and the reference number of threads of the outer threaded portion 34 of the sun shaft 3 is indicated as the reference number of sun threads ZSS, the crown shaft 2 or The sun shaft 3 is moved forward by setting the number of threads such that one of the following [Expressions 82] and [Expressions 83] is satisfied.
A separate setting method will be given in “Separate examples of the method for setting the number of thread turns.”
The main items representing the specifications of the conversion mechanism 1 of the second embodiment include the following items (A) to (E), including the reference pitch diameter ratio and the number of teeth ratio.
(A) Motion conversion mode
(B) Ratio of solar/planetary threaded sections
(C) Number of planetary shafts
(D) Ratio of thread numbers of threaded sections
(E) Number of effective threads
The details of the above items will be described below.
"Motion conversion mode" in (A) represents an operating mode for converting rotational motion into linear motion. That is, when the sun shaft 3 moves forward through the rotational movement of the crown shaft 2, the motion conversion mode is in the “sun shaft moving mode.” In addition, when the crown shaft 2 moves forward through the rotational movement of the sun shaft 3, the motion conversion mode is in the “ring shaft moving mode.”
The “solar/planetary threaded portion ratio” of (B) represents the twist direction ratio between the outer threaded portion 34 of the sun shaft 3 and the outer threaded portions 44 of the planetary shaft 4. That is, when the twist direction of the outer threaded portion 34 of the sun shaft 3 and the twist direction of the outer The threaded sections 44 of the planetary shafts 4 are opposite to each other, the ratio of the solar/planetary threaded sections is “reverse direction”. In addition, when the twist direction of the outer threaded portion 34 of the sun shaft 3 and the twist direction of the outer threaded portions 44 of the planetary shaft 4 are the same as each other, the ratio of the sun/planetary threaded portions is “forward direction.”
The "number of planetary shafts" in (C) represents the number of planetary shafts 4 located around the sun shaft 3.
The "ratio of thread numbers of threaded sections" in (D) represents the ratio of the number of threads of the solar threaded section ZSs, the number of threads of the planetary threaded section ZSp, and the number of threads of the annular threaded section ZSr. That is, the ratio of the numbers of thread turns of threaded sections is ZSs:ZSp:ZSr.
The “number of effective threads” in (E) represents the difference between the actual number of threads of a threaded section (number of threads in (D)) and the reference number of threads. That is, when the motion conversion mode is in the sun shaft motion mode, the number of effective threads is a value obtained by subtracting the reference number of solar threads ZSS from the number of threads of the solar threaded section ZSs in (D). In addition, when the motion conversion mode is in the annular shaft moving mode, the number of effective threads is a value obtained by subtracting the reference number of the annular threads, ZSR, from the thread number of the annular threaded portion, ZSr, in (D).
Example 1 installation
(A) Motion conversion mode: “solar shaft moving mode”
(B) Solar/planetary threaded section ratio: “reverse direction”
(C) Number of planetary shafts: "9"
(D) Ratio of thread numbers of threaded sections: "4:1:5"
(F) Number of effective threads: "1"
Installation example 2
(A) Motion conversion mode: “ring shaft moving mode”
(B) Solar/planetary threaded section ratio: “reverse direction”
(C) Number of planetary shafts: "9"
(D) Ratio of thread numbers of threaded sections: “3:1:6”
(E) Number of effective threads: "1"
The conversion mechanism 1 of the second embodiment further uses the following setting method for the number of teeth and the reference pitch diameter of the gears and the number of thread turns and the reference pitch diameter of the threaded portions.
[A] The effective diameter of the planetary threaded section DSp and the effective diameter of the planetary gear DGp are set to the same size. In addition, the ratio of the number of teeth of the planetary gear ZGp and the number of teeth of the ring gear ZGr is set to the same size as the ratio of the effective diameter of the planetary threaded portion DSp and the effective diameter of the annular threaded portion DSr. Thus, the ratio of the number of teeth of the planetary gear ZGp and the number of teeth of the ring gear ZGr is equal to the ratio of the number of threads of the planetary threaded section ZSp and the number of threads of the annular threaded section ZSr. Thus, the ratio of the rotation amount of the ring shaft 2 and the planetary shafts 4 is precisely limited by the ratio of the number of teeth of the ring gears 22, 23 and the planetary gears 42, 43. Moreover, the ratio of the effective diameter of the planetary threaded portion DSp and the effective diameter of the annular threaded portion DSr is maintained with respect to effective diameter, which must be set initially.
[B] The effective diameter of the planetary threaded portion DSp and the effective diameter of the planetary gear DGp are set to the same size. In addition, the ratio of the number of planetary gear teeth ZGp and the number of sun gear teeth ZGs is set to the same size as the ratio of the effective diameter of the planetary threaded portion DSp and the effective diameter of the sun threaded portion DSs. Thus, the ratio of the number of planetary gear teeth ZGp and the number of sun gear teeth ZGs is equal to the ratio of the number of threads of the planetary threaded section ZSp and the number of threads of the sun threaded section ZSs. Thus, the rotation amount ratio of the sun shaft 3 and the planetary shafts 4 is precisely limited by the ratio of the number of teeth of the sun gears 32, 33 and the planetary gears 42, 43. Moreover, the ratio of the effective diameter of the planetary threaded portion DSp and the effective diameter of the sun threaded portion DSs is maintained at the ratio effective diameter, which must be set initially.
As described above, the conversion mechanism 1 according to the second embodiment has advantages that are the same as those of (1) to (4) and (5) of the first embodiment.
The second embodiment may be modified as will be described below.
In the second embodiment, the front ring gear 22 and/or the rear ring gear 23 may not be used. That is, the configuration may be modified such that the front planetary gear 42 and/or the rear planetary gear 43 do not mesh with the ring shaft 2.
In the second embodiment, the front sun gear 32 and/or the rear sun gear 33 may not be used. That is, the configuration may be modified such that the front planet gear 42 and/or the rear planet gear 43 do not mesh with the sun shaft 3.
CLAIM
1. A rotational/translational motion conversion mechanism, comprising:
an annular shaft having a space extending therein in an axial direction, the annular shaft including an internal threaded portion and first and second ring gears, the ring gears being internal gears,
a sun shaft disposed within the annular shaft and including an outer threaded portion and first and second sun gears, the sun gears being external gears, and
a plurality of planetary shafts disposed about the sun shaft, each of which includes an outer threaded portion and first and second planetary gears, the planetary gears being external gears,
wherein the outer threaded portion of each planetary shaft meshes with the inner threaded portion of the ring shaft and with the outer threaded portion of the sun shaft, each first planetary gear meshes with the first ring gear and the first sun gear, each second planetary gear meshes with the second ring gear and the second a sun gear, wherein the conversion mechanism converts the rotational motion of one of the annular shaft and the sun shaft into a translational motion of the other one of the annular shaft and the sun shaft along an axial direction due to the planetary motion of the planetary shafts,
wherein the planetary shafts are configured to provide relative rotation between the first planetary gear and the second planetary gear.
2. The conversion mechanism according to claim 1, wherein each planetary shaft is formed by a combination of a planetary shaft main body formed integrally with an outer threaded portion and the first planetary gear, and a second planetary gear formed separately from the planetary shaft main body, wherein the second The planetary gear is designed to rotate relative to the main body of the planetary shaft.
3. The conversion mechanism according to claim 1, wherein each planetary shaft is formed by a combination of a planetary shaft main body integral with the outer threaded portion, and a first planetary gear and a second planetary gear that are formed separately from the planetary shaft main body, wherein the first planetary gear and the second planetary gear are rotatable relative to the main body of the planetary shaft.
4. The conversion mechanism according to claim 1, wherein each annular shaft is formed by a combination of a main body of the annular shaft integral with the internal threaded portion, and a first ring gear and a second ring gear that are formed separately from the main body of the annular shaft, wherein the first ring gear and the second ring gear are rotatable relative to the main body of the planetary shaft.
5. The conversion mechanism according to claim 1, wherein the internal threaded portion, the first ring gear and the second ring gear of the ring shaft are configured to move together.
6. The conversion mechanism according to claim 1, wherein the sun shaft is formed by a combination of a sun shaft main body formed integrally with the outer threaded portion and the first sun gear, and a second sun gear formed separately from the sun shaft main body, wherein the second sun gear the gear is configured to move relative to the main body of the solar shaft.
7. The conversion mechanism according to claim 1, wherein the outer threaded portion, the first sun gear and the second sun gear of the sun shaft are movable together.
8. The conversion mechanism according to claim 1, wherein, when the ratio of the number of teeth of each ring gear, the number of teeth of each sun gear and the number of teeth of each planetary gear is specified as the ratio of the number of teeth, and the ratio of the reference pitch diameter of each ring gear, the reference pitch diameter of each sun gear and the reference pitch diameter of each planetary gear is specified as the ratio of the effective diameters, the ratio of the number of teeth and the ratio of the effective diameters are set to different values.
9. The conversion mechanism of claim 1, wherein the radial position of the sun shaft is limited by the bearing member attached to the annular shaft, the engagement of the threaded sections and the engagement of the gears, and the radial position of the planetary shaft is limited by the engagement of the threaded sections and the engagement of the gears.
10. The conversion mechanism according to claim 9, wherein the bearing element is a pair of bearings attached to the annular shaft to cover open areas at the ends of the annular shaft, and the bearing element is provided with holes for supplying lubricant to the meshing portion of the threaded portions and the gear meshing portion between the annular shaft , solar shaft and planetary shaft.
11. The conversion mechanism according to claim 1, wherein the first ring gear and the second ring gear have the same shape, the first sun gear and the second sun gear have the same shape, and the first planet gear and the second planet gear have the same shape.
12. The conversion mechanism according to claim 11, wherein, when the number of threads of the outer threaded portion of the planetary shaft is indicated as the number of threads of the planetary threaded portion, the number of threads of the outer threaded portion of the sun shaft is indicated as the number of threads of the sun threaded portion, the number of teeth of the planetary gear is indicated as the number of teeth of the planetary gear, and the number of teeth of the sun gear is indicated as the number of teeth of the sun gear, the ratio of the number of threads of the sun threaded part to the number of threads of the planetary threaded part is different from the ratio of the number of teeth of the sun gear to the number of teeth of the planetary gear,
13. The conversion mechanism according to claim 11, wherein, when the number of threads of the outer threaded portion of the planetary shaft is indicated as the number of threads of the planetary threaded portion, the number of threads of the outer threaded portion of the annular shaft is indicated as the number of threads of the annular threaded portion, the number of planetary teeth gear is specified as the number of teeth of the planetary gear, and the number of teeth of the ring gear is specified as the number of teeth of the ring gear, the ratio of the number of threads of the ring threaded part to the number of threads of the planetary threaded part is different from the ratio of the number of teeth of the ring gear to the number of teeth of the planetary gear,
in this case, the solar shaft moves translationally due to the planetary movement of the planetary shafts accompanying the rotational movement of the annular shaft.
14. The conversion mechanism according to any one of claims 1 to 10, wherein the twisting direction of the inner threaded portion of the annular shaft and the twisting direction of the outer threaded portions of the planetary shafts are in the same direction as each other, the twisting direction of the outer threaded portion of the sun shaft and the twisting direction the outer threaded sections of the planetary shafts are in opposite directions to each other, and the inner threaded section of the annular shaft, the outer threaded section of the sun shaft and the outer threaded sections of the planetary shafts have the same thread pitches as any other,
Moreover, in the case where the ratio of the reference pitch diameter and the number of thread turns of the threaded sections of the annular shaft, sun shaft and planetary shafts, if relative movement in the axial direction does not occur between the annular shaft, sun shaft and planetary shafts, is indicated as the reference ratio, and the number The number of threads of the outer threaded portion of the solar shaft is different from the number of threads in the support ratio, and
in this case, the solar shaft moves translationally due to the planetary movement of the planetary shafts, accompanied by the rotational movement of the annular shaft.
15. The conversion mechanism according to any one of claims 1 to 10, wherein the twisting direction of the inner threaded portion of the annular shaft and the twisting direction of the outer threaded portions of the planetary shafts are in the same direction as each other, the twisting direction of the outer threaded portion of the sun shaft and the twisting direction the outer threaded portions of the planetary shafts are in opposite directions to each other, wherein the inner threaded portion of the annular shaft, the outer threaded portion of the sun shaft, and the outer threaded portions of the planetary shafts have the same thread pitches as any other,
Moreover, in the case where the ratio of the reference pitch diameter and the number of thread turns of the threaded sections of the annular shaft, sun shaft and planetary shafts, if relative movement in the axial direction does not occur between the annular shaft, sun shaft and planetary shaft, is indicated as the reference ratio, and the number the number of thread turns of the internal threaded section of the annular shaft differs from the number of thread turns in the supporting ratio,
in this case, the annular shaft moves translationally due to the planetary movement of the planetary shafts, accompanied by the rotational movement of the solar shaft.
Lipetsk College of Transport and Road Management
Research work of students of group K2-14
Topic: “Study of the operation of mechanisms for transforming motion
Lipetsk
2015/2016 academic year
Content
1.Introduction (historical foundations of the issue of movement transformation)
2. Relevance of the research (applied nature of the hypothesis),
3. Purpose of the study
3. Methods and methods of research work
6. Conclusions and suggestions
7. Project presentation
1. Introduction
Mechanisms for converting motion
Brief overview of the history of the development of simple mechanisms
According to the classification existing in mechanics, DPE belongs to the family of the simplest mechanisms that have faithfully served man for centuries, such as a wheel, a block, a lever, and a gate.
All of them are originally giveninto action by the muscular power of a person and their practical value lies in the multiple multiplication (strengthening) of the original muscular effect. Each of these mechanisms has undergone a long test of practice and time, and in fact they have become a kind of “bricks” (elementary links) from which a great variety of complex mechanisms are built. Of course, the wheel occupies a special place among these mechanisms; because it was with his help that it was carried outcontinuous conversion of mechanical energy using as a sourcegravity.
We are talking, of course, aboutconverter,known aswater wheel , which later becamehydraulic turbine (which increased the efficiency of the mechanism, leaving the operating principle the same).
Latissimusthe use of this type of converter is explained very simply: its idealcompatibility (in the simplest case - through one common axis of rotation) with the most importantmillstone , and later -electric generator .
It is also interesting to use a water wheel in “inverse (reverse) activation” forrise water, using the “input” human muscular strength.
However, not all loads were of a rotational nature (for example, forpowerful blacksmith bellowsa reciprocating type converter would be better suited), and then it was necessary to resort to intermediate converters (such as a crank mechanism), which introduce losses into the conversion process and increase complexity and costsystems. We find many examples of the need to use intermediate converters during the transition from rotational motion to reciprocating motion in ancient drawings and engravings.
The figure below, for example, shows the mating of a rotatingwater wheelwith a piston pump - a mechanical load requiring reciprocating movement of the drive mechanism.
Thus, the usefulness and relevance of
for many practical applicationsreciprocating type energy converters driven by the same force of gravity.
The most suitable simple mechanismin this case islever arm.
Leverage, in the full sense- strength amplifier. Therefore, it has found wide application in lifting weights, for example,in construction (classic example- construction of the pyramids by the Egyptians). However, in this application
the “input” influence was the same muscularthe efforts of people, and the mode of operation of the lever was, of course, discrete.
There is another interesting practicalexample of using a lever asenergy converter: this is an ancient fighting throwing machine -trebuchet.
Trebuchet is interesting due to its new fundamental difference from the classical use of a lever: it is activatedalreadygravity (and not by muscular force) of the falling mass. However, it is not possible to recognize the trebuchet as an energy converter with the ability to connect a payload. Firstly, this is a mechanism of a single (one-time) action, and secondly, to charge it (lift the load) the same muscular force is required (albeit reinforced with the help of blocks and gates).
However, creative thought is looking for new ways in attempts to couple the lever with the payload and use gravity as a force.the original driving force.
Mechanisms that transform movement: rack and pinion, screw, crank, rocker, cam. Their details, characteristics and features of intended use in various branches of production and light industry. Schemes of their operation in various machines.
To activate the working bodies, as well as to convert one type of movement into another, crank, cam and other mechanisms are used.
Crank mechanism. Such a mechanism converts rotational motion into translational motion. A shaft with a crank rotates in the stationary bearings of the frame, connected by a hinge to one end of the connecting rod. The other end of the connecting rod is connected by a hinge to a slider sliding in fixed straight guides. If the crank rotates continuously, the slider makes a reciprocating motion. During one revolution of the crank, the slider makes two moves - first in one direction and then in the opposite direction.
The crank mechanism is used in steam engines, internal combustion engines, piston pumps, etc. The position of the crank at the top point of the translational stroke is called the dead center. To move the crank to this position, when it is the leading link of the mechanism, a flywheel is designed - a wheel with a heavy rim mounted on the crank shaft. The kinetic energy of the flywheel ensures the continuous movement of the crank mechanism.
Cam mechanism. Such a mechanism converts rotational motion into translational motion in various types of automatic machines, metal-cutting machines and other machines. The cam, rotating around an axis, imparts a reciprocating motion to the pusher.
The movement of the pushrod depends on the cam profile. If the cam profile represents an arc of a circle described from the center, then the pusher in this section will be stationary. Such a cam mechanism is called flat.
Converting rotational motion to linear motion
Rocker mechanisms
Cam mechanisms
Articulating lever mechanisms
Crank mechanisms
Crank mechanisms serve to convert rotational motion into reciprocating motion and vice versa. The main parts of the crank mechanism are: a crank shaft, a connecting rod and a slider, connected to each other by a hinge (a). The stroke length of the slider can be any length; it depends on the length of the crank (radius). If we denote the length of the crank by the letter A, and the stroke of the slider by B, then we can write a simple formula: 2A = B, or A = B/2. Using this formula, it is easy to find both the stroke length of the slider and the length of the crank. For example: the stroke of the slider B = 50 mm, you need to find the length of the crank A. Substituting a numerical value into the formula, we get: A = 50/2 = 25 mm, that is, the length of the crank is 25 mm.
a - the operating principle of the crank mechanism,
b - single-cranked shaft, c - multi-cranked shaft,
g - mechanism with eccentric
In a crank mechanism, a crankshaft is often used instead of a crank shaft. This does not change the essence of the mechanism. The crankshaft can have either one elbow or several (b, c).
A modification of the crank mechanism can also be an eccentric mechanism (d). The eccentric mechanism has no crank or knees. Instead, a disk is mounted on the shaft. It is not mounted in the center, but offset, that is, eccentrically, hence the name of this mechanism - eccentric.
In some crank mechanisms, it is necessary to change the stroke length of the slider. This is usually done with a crank shaft. Instead of a solid curved crank, a disk (faceplate) is mounted on the end of the shaft. The spike (the leash on which the connecting rod is put) is inserted into a slot made along the radius of the faceplate. By moving the tenon along the slot, that is, moving it away from the center or bringing it closer to it, we change the size of the slider's stroke.
The stroke of the slider in crank mechanisms is uneven. It is the slowest in places with backlash.
Crank-rod mechanisms used in engines, presses, pumps, and in many agricultural and other machines.
Rocker mechanisms
Reciprocating motion in crank mechanisms can be transmitted without a connecting rod. A cut is made in the slider, which in this case is called the slider, across the movement of the slider. The crank pin is inserted into this slot. When the shaft rotates, the crank, moving left and right, moves the slide along with it.
a - forced link, b - eccentric with a spring roller,
c - rocking link
Instead of a slide, you can use a rod enclosed in a guide sleeve. To fit against the eccentric disk, the rod is equipped with a pressure spring. If the rod works vertically, its contact is sometimes achieved by its own weight.
For better movement along the disk, a roller is installed at the end of the rod.
Cam mechanisms
Cam mechanisms serve to convert rotational motion (cam) into reciprocating or other specified type of motion. The mechanism consists of a cam - a curved disk mounted on a shaft, and a rod, which at one end rests on the curved surface of the disk. The rod is inserted into the guide sleeve. For a better fit to the cam, the rod is equipped with a pressure spring. To make the rod slide easily along the cam, a roller is installed at its end.
a - flat cam, b - cam with a groove, c - drum-type cam,
d - heart-shaped cam, d - simplest cam
But there are disc cams of other designs. Then the roller slides not along the contour of the disk, but along a curved groove taken out from the side of the disk (b). In this case, a compression spring is not required. The movement of the roller with the rod to the side is carried out by the groove itself.
In addition to the flat cams (a) we examined, you can also find drum-type cams (c). Such cams are a cylinder with a curved groove around its circumference. A roller with a rod is installed in the groove. The cam, rotating, drives the roller in a curved groove and thereby imparts the desired movement to the rod. Cylindrical cams come not only with a groove, but also one-sided - with an end profile. In this case, the roller is pressed against the cam profile by a spring.
In cam mechanisms, swinging levers (c) are often used instead of a rod. Such levers allow you to change the length of the stroke and its direction.
The stroke length of the rod or lever of a cam mechanism can be easily calculated. It will be equal to the difference between the small radius of the cam and the large one. For example, if the large radius is 30 mm and the small radius is 15, then the stroke will be 30-15 = 15 mm. In a mechanism with a cylindrical cam, the stroke length is equal to the amount of displacement of the groove along the cylinder axis.
Due to the fact that cam mechanisms make it possible to obtain a wide variety of movements, they are often used in many machines. Uniform reciprocating motion in machines is achieved by one of the characteristic cams, which is called heart-shaped. With the help of such a cam, the shuttle bobbin of the sewing machine is wound uniformly.
Articulating lever mechanisms
Often in machines it is necessary to change the direction of movement of some part. Suppose the movement occurs horizontally, but it must be directed vertically, to the right, to the left, or at some angle. In addition, sometimes the stroke length of the operating lever needs to be increased or decreased. In all these cases, hinged lever mechanisms are used.
The figure shows a hinged lever mechanism connected to other mechanisms. The lever mechanism receives the rocking motion from the crank and transmits it to the slider. The stroke length of a hinged lever mechanism can be increased by changing the length of the lever arm. The longer the arm, the greater will be its swing, and therefore the feed of the part associated with it, and vice versa, the smaller the arm, the shorter the stroke.
2. Relevance of the research (applied nature of the hypothesis)
Working with various mechanisms has become an integral part of our lives today. We use motion transformation mechanisms without thinking about how they are implemented and why they make our life easier.
The relevance of the topic of our work is determined by the fact that currently the role of such mechanisms in modern life is not fully appreciated; in the process of training in our profession, such mechanisms are important.
In the modern world, the study of motion transformation mechanisms is an important part of the entire training course for the profession of “Crane Operator”, since knowing the basic principles of the execution of operating bodies, lifting mechanisms, the operation of the internal combustion engine, and the transformation of motion in the chassis of the car. Therefore, the hypothesis of our study will be the following version.With active study of the operation of such mechanisms, practical work on various types of production practices becomes more active. (training driving in a car, educational practice on a truck crane)
Many people are interested and passionate about studying, designing and modeling various mechanisms, including motion transformation mechanisms
Probably every person at least once in his life thought about how to make his life easier and create the necessary convenience in materials processing, transport management, construction
People have always raised many questions about the operation of such mechanisms. Studying the history of the issue, we came to the conclusion that such mechanisms are being improved with the development of technology
3. Purpose of the study
Goal of the work
Goal of the work - study what role motion transformation mechanisms play in modern technology
The main goal of the work is to answer the question why it is important to study in detail the mechanisms of motion transformation in the process of mastering the profession of “Crane Operator”; we also want to prove that active study of such machines and mechanisms helps to successfully complete various practical works.
4. Objectives of the research work
To achieve this goal, we need to solve the following tasks:
Job objectives:
1. Study the literature on the topic of motion transformation mechanisms
2. Find out the meaning of the terms crank mechanism, cam mechanism, hinge mechanism and other types of mechanisms.
3. Find examples in technology, everyday life, collect material for organizing data, make a model of mechanisms
4. Observe the operation of such mechanisms in practical work
5.Compare the results obtained
6.Draw conclusions about the work done
5. Practical foundations of research work (models, projects, illustrative examples)
photo
6. Conclusions and suggestions
The study may be useful and interesting to students of professional institutions who study such mechanisms, as well as to anyone interested in technology.
With our work we wanted to attract students' attention to the problem of studying the mechanisms of motion transformation.
In the process of working on the research, we gained experience... I think that the knowledge I acquired will allow me to avoid mistakes / help me correctly...
The results of the study got me thinking...
What gave me the most difficulty was...
The research has fundamentally changed my opinion/perception about...
A transmission is a technical device for transmitting one or another type of movement from one part of the mechanism to another. Transfer occurs from the source of energy to the place of its consumption or transformation. The first transmission mechanisms were developed in the ancient world and were used in the irrigation systems of Ancient Egypt, Mesopotamia and China. Medieval mechanics significantly improved devices that transmit movement and developed many new types, using them in spinning wheels and pottery. The real flourishing began in modern times, with the introduction of production technologies and precision processing of steel alloys.
Various types of gears are used in various machines, household appliances, vehicles and other mechanisms.
Typically the following types of transmission are distinguished: :
- rotational movement;
- rectilinear or reciprocating;
- movement along a certain trajectory.
The most widely used type of mechanical transmission is rotary.
Features of the gear mechanism
Such mechanisms are designed to transmit rotation from one gear to another using the meshing of teeth. They have relatively low friction losses compared to clutches, since the wheelset does not need to be pressed tightly against each other.
A pair of gears converts the speed of rotation of the shaft in inverse proportion to the ratio of the number of teeth. This ratio is called . Thus, a wheel with five teeth will rotate 4 times faster than a 20-tooth wheel meshed with it. The torque in such a pair will also decrease by 4 times. This property is used to create gearboxes that reduce rotation speed as torque increases (or vice versa).
If it is necessary to obtain a large gear ratio, then one pair of gears may not be enough: the gearbox will be very large. Then several successive pairs of gears are used, each with a relatively small gear ratio. A typical example of this type is a car gearbox or a mechanical watch.
The gear mechanism is also capable of changing the direction of rotation of the drive shaft. If the axes lie in the same plane, bevel gears are used, if in different ones, then a worm or planetary type transmission is used.
To implement movement with a certain period, one (or several) teeth are left on one of the gears. Then the output shaft will move at a given angle only every full revolution of the drive shaft.
If you turn one of the gears onto a plane, you get a gear rack. Such a pair can convert rotational motion into linear motion.
Gear Parameters
In order for the gears to engage and effectively transmit movement, it is necessary that the teeth precisely match each other along the profile. The main parameters used in the calculation are regulated:
- Diameter of the starting circle.
- The engagement pitch is the distance between adjacent teeth, determined along the line of the initial circle.
- Module. – The ratio of the step to the constant π. Gears with equal modulus always engage, regardless of the number of teeth. The standard prescribes an acceptable range of module values. All the main parameters of the gear are expressed through the module.
- Tooth height.
Important parameters are also the height of the head and base of the tooth, the diameter of the circle of the protrusions, the contour angle and others.
Advantages
Gear-type transmissions have a number of obvious advantages. This:
- conversion of motion parameters (speed and torque) within a wide range;
- high fault tolerance and service life;
- compactness;
- low losses and high efficiency;
- light axle loads;
- stability of the gear ratio;
- easy maintenance and repair.
Flaws
Gear mechanisms also have certain disadvantages:
- Manufacturing and assembly require high precision and special surface treatment.
- Unavoidable noise and vibration, especially at high speeds or high forces
- The rigidity of the structure leads to breakdowns when locking the driven shaft.
When choosing a transmission type, the designer compares the advantages and disadvantages for each specific case.
Mechanical gears
Mechanical transmissions serve to transmit rotation from the drive shaft to the driven one, from the place of generation of mechanical energy (usually an engine of one type or another) to the place of its consumption or transformation.
As a rule, engines rotate their shaft with a limited range of changes in speed and torque. Consumers require wider ranges.
According to the method of transferring mechanical energy, the following types are distinguished among gears:
- toothed;
- screw;
- flexible.
- frictional
Gear transmission mechanisms, in turn, are divided into types such as:
- cylindrical;
- conical;
- Novikov's profile.
Based on the ratio of the rotation speed of the drive and driven shafts, a distinction is made between gearboxes (reducing speed) and multipliers (increasing speed). A modern manual transmission for a car combines both types, being both a reducer and a multiplier.
Functions of mechanical gears
The main function of mechanical transmissions is to transfer kinetic energy from its source to consumers, working bodies. In addition to the main one, transmission mechanisms also perform additional functions:
- Change in speed and torque. At a constant amount of motion, changes in these quantities are inversely proportional. For step changes, replaceable gear pairs are used; for smooth changes, belt or torsion variators are suitable.
- Changing the direction of rotation. Includes both conventional reverse and changing the direction of the rotation axis using conical, planetary or cardan mechanisms.
- Conversion of motion types. Rotational into linear, continuous into cyclic.
- Distribution of torque between several consumers.
Mechanical transmissions also perform other auxiliary functions.
Mechanical engineers have adopted several classifications depending on the classifying factor.
Based on the principle of operation, the following types of mechanical transmissions are distinguished:
- engagement;
- rolling friction;
- flexible links.
According to the direction of change in the speed, gearboxes (decrease) and multipliers (increase) are distinguished. Each of them changes the torque accordingly (in the opposite direction).
According to the number of consumers of transmitted rotational energy, the form can be:
- single-threaded;
- multi-threaded
According to the number of transformation stages - single-stage and multi-stage.
Based on the transformation of types of motion, the following types of mechanical transmissions are distinguished:
- Rotational-translational. Worm, rack and screw.
- Rotational-swinging. Lever pairs.
- Translational-rotational. Cranks are widely used in internal combustion engines and steam engines.
To ensure movement along complex specified trajectories, systems of levers, cams and valves are used.
Key indicators for choosing mechanical gears
Selecting the type of transmission is a complex design task. It is necessary to select a type and design a mechanism that most fully satisfies the technical requirements formulated for a given unit.
When choosing, the designer compares the following main factors:
- experience of previous similar designs;
- power and torque on the shaft;
- number of revolutions at the input and output;
- required efficiency;
- weight and size characteristics;
- availability of adjustments;
- planned operational resource;
- production cost;
- cost of service.
For high transmitted powers, a multi-thread gear type is usually chosen. If you need to adjust the speed over a wide range, it would be wise to choose a V-belt variator. The final decision remains with the designer.
Helical gears
Mechanisms of this type are made with internal or external gearing. If the teeth are located at an angle to the longitudinal axis, the gear is called helical. As the angle of inclination of the teeth increases, the strength of the pair increases. Helical gearing is also characterized by better wear resistance, smooth running and low noise and vibration levels.
If it is necessary to change the direction of rotation, and the shaft axes lie in the same plane, a bevel type of transmission is used. The most common angle of change is 90°.
This type of mechanism is more complex to manufacture and install and, like the helical one, requires strengthening of the supporting structures.
A conical mechanism can transmit up to 80% of the power compared to a cylindrical mechanism.
Rack and belt gear transmission
Standards
The main parameters of various types of gears are standardized by the relevant GOSTs:
- Toothed cylindrical: 16531-83.
- Worm 2144-76.
- Involute 19274-73.
Download GOST 16531-83
The most common mechanisms for converting rotational motion into linear motion are those familiar to us from Fig. 1 crank and according to Fig. 7, d - rack and pinion, as well as screw, eccentric, rocker, ratchet and other mechanisms.
Screw mechanisms
Screw mechanisms are widely used in a wide variety of machines to convert rotational motion into translational motion and, conversely, translational motion into rotational motion. Especially often screw mechanisms used in machine tools to carry out linear auxiliary (feed) or installation (approach, retraction, clamping) movement of such assembly units as tables, supports, carriages, spindle heads, heads, etc.
The screws used in these mechanisms are called running screws. Often also screw mechanism serves for lifting loads or generally for transmitting forces. An example of such an application screw mechanism is to use it in jacks, screw ties, etc. In this case, the screws will be called cargo screws. Load screws usually operate at low speeds, but with greater forces compared to lead screws.
Main details screw mechanism are a screw and a nut.
Usually in screw mechanisms(screw-nut transmissions) the movement is transmitted from the screw to the nut, i.e. the rotational movement of the screw is converted into the translational movement of the nut, for example, the mechanism of transverse movement of the support of a lathe. There are designs where the motion is transmitted from the nut to the screw, and screw gears in which the rotation of the screw is converted into translational motion of the same screw, with the nut fixed motionless. An example of such a mechanism would be helical gear the upper part of the table (Fig. 9, a) of the milling machine. When handle 6 rotates screw 1 in nut 2, secured by screw 3 in table slide 4, 5, screw 1 begins to move forward. Table 5 moves along the slide guides with it.
Eccentric and cam mechanisms
Scheme eccentric mechanism shown in Fig. 9, b. The eccentric is a round disk, the axis of which is offset relative to the axis of rotation of the shaft carrying the disk. When shaft 2 rotates, eccentric 1 acts on roller 3, moving it and the associated rod 4 upward. The roller is returned down by spring 5. Thus, the rotational movement of shaft 2 is converted eccentric mechanism into the forward movement of the rod 4.
Cam mechanisms widely used in automatic machines and other machines to implement an automatic work cycle. These mechanisms can be with cylindrical disk and mechanical cams. Shown in Fig. 9, the mechanism consists of a cam 1 with a groove 2 of complex shape at the end, in which a roller 3 is placed, connected to the slider 4 by means of a rod 5. As a result of the rotation of the cam 1 (in its different sections), the slider 4 receives different speeds of a rectilinear reciprocating movements.
Rocker mechanism
In Fig. 9, d shows the diagram rocker mechanism, widely used, for example, in cross-planing and slotting machines. With the slider 1, on which the support with the cutting tool is attached, a part 4 swinging left and right, called the rocker, is hingedly connected by means of an earring 2. At the bottom, the rocker is connected by means of a hinge 6, and with its lower end it rotates about this axis during swings.
The rocking of the rocker occurs as a result of translational and reciprocal movements in its groove of the part 5, called the rocker stone and receiving movement from the gear 3 with which it is connected. To gear 3, called the rocker gear, rotation is transmitted by a wheel mounted on the drive shaft. The speed of rotation of the rocker wheel is controlled by a gearbox connected to an electric motor.
The stroke length of the slider depends on the type of rocker stone installed on the rocker gear. The farther the rocker stone is from the center of the gear, the larger the circle it describes when the gear rotates, and, consequently, the greater the swing angle of the rocker and the longer the stroke of the slider. And vice versa, the closer to the center of the wheel the rocker stone is installed, the less all the listed movements are.
Ratchets
Ratchets allow you to change the amount of periodic movements of the working parts of machines over a wide range. The types and applications of ratchet mechanisms are varied.
Ratchet mechanism(Fig. 10) consists of four main links: rack 1, ratchet (gear) 4, lever 2 and part 3 with a protrusion, which is called a pawl. A ratchet with teeth beveled in one direction is mounted on the driven shaft of the mechanism. On the same axis with the shaft, a lever 2 is hinged, rotating (swinging) under the action of the drive rod 6. A pawl is also hinged on the lever, the protrusion of which has a shape corresponding to the cavity between the teeth of the ratchet.
During work ratchet mechanism lever 2 begins to move. When it moves to the right, the pawl slides freely along the rounded part of the ratchet tooth, then, under the influence of its gravity or a special spring, it jumps into the cavity and, resting against the next tooth, pushes it forward. As a result of this, the ratchet, and with it the driven shaft, rotates. Reverse rotation of the ratchet with the driven shaft when the lever with pawl 3 is idling is prevented by a locking pawl 5, hinged on a fixed axis and pressed against the ratchet by a spring.
The described mechanism converts the rocking motion of the lever into intermittent rotational motion of the driven shaft.
