Mechanisms of rectilinear movements. Rotary motion transmission mechanisms - repair of industrial equipment Conversion of linear motion into rotational motion

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1. Mechanisms for converting motion

The mechanical energy of many machine engines is usually the energy of a rotating shaft. However, not all machines and mechanisms have working bodies that also perform rotational motion. Often they need to communicate forward or reciprocating motion. The opposite picture is also possible. In such cases, mechanisms that transform movement are used. These include: rack and pinion, screw, crank, rocker and cam mechanisms.

1 .1 Rack and pinion mechanism

The rack and pinion mechanism consists of a cylindrical gear and a rack - a strip with teeth cut on it. Such a mechanism can be used for various purposes: by rotating a gear on a fixed axis, to move the rack translationally (for example, in a rack jack, in the feed mechanism of a drilling machine); When rolling a wheel on a stationary rack, move the wheel axis relative to the rack (for example, when performing longitudinal feed of a caliper in a lathe).

1 .2 Screw mechanism

To convert rotational motion into translational motion, a mechanism is often used, the main parts of which are a screw and a nut. This mechanism is used in various designs:

the nut (the internal thread is threaded in the body) is stationary, the screw rotates and at the same time moves forward;

the nut is stationary, the screw rotates and simultaneously moves forward with the slide. The slide is pivotally connected to the screw and can perform reciprocating movement depending on the direction of movement of the screw along the guides;

the screw is fixed so that it can only rotate, and the nut (in this case, the slide) is unable to rotate, since its lower (or other) part is installed between the guides. In this case, the nut (slide) will move forward.

The screw mechanisms listed above use threads. of various profiles, most often rectangular and trapezoidal (for example, in a bench vice, jacks, etc.). If the angle of elevation of the helix is ​​small, then the leading movement is rotational. With a very large helix angle, it is possible to convert translational motion into rotational motion, and a high-speed screwdriver can serve as an example of this.

1 .3 Crank mechanism

A crankpin is a link in a crank mechanism that can make a full revolution around a fixed axis. The crank (I) has a cylindrical protrusion - a spike 1 , the axis of which is displaced relative to the axis of rotation of the crank by a distance G, which can be permanent or adjustable. A more complex rotating part of the crank mechanism is the crankshaft. Eccentric (III) - a disk mounted on a shaft with eccentricity, that is, with a displacement of the axis of the disk relative to the axis of the shaft. The eccentric can be considered as a design variation of the crank with a small radius.

A crank mechanism is a mechanism that converts one type of movement into another. For example, uniform rotation - into translational, rocking, uneven rotation, etc. The rotating link of the crank mechanism, made in the form of a crank or crankshaft, is connected to the rack and the other link by rotational kinematic pairs (hinges). It is customary to distinguish such mechanisms into crank-rod, crank-rocker, crank-rocker, etc., depending on the nature of the movement and the name of the link with which the crank works.

Crank mechanisms are used in piston engines, pumps, compressors, presses, in driving movement of metal-cutting machines and other machines.

The crank mechanism is one of the most common motion conversion mechanisms. It is used both to convert rotary motion into reciprocating motion (for example, piston pumps), and to convert reciprocating motion into rotational motion (for example, internal combustion engines).

A connecting rod is a part of a crank-rod (slider) mechanism that transmits the movement of a piston or slider to the crankshaft crank. The part of the connecting rod that connects to the crankshaft is called the crank head, and the opposite part is called the piston (or slide) head.

The mechanism consists of a stand 1 ,crank 2, connecting rod 3 and slider 4. The crank performs continuous rotation, the slider performs a reciprocating movement, and the connecting rod performs a complex, plane-parallel movement.

The full stroke of the slider is equal to twice the length of the crank. Considering the movement of the slider from one position to another, it is easy to see that when the crank is turned at equal angles, the slider travels different distances: when moving from the extreme position to the middle, the sections of the slider’s path increase, and when moving from the middle position to the extreme, they decrease. This indicates that with uniform movement of the crank, the slider moves unevenly. Thus, the speed of movement of the slider changes from zero at the beginning of its movement and reaches its greatest value when the crank and connecting rod form a right angle with each other, then decreases again to zero at the other extreme position.

The uneven movement of the slide causes inertial forces to appear, which have a negative impact on the entire mechanism. This is the main disadvantage of the crank-slider mechanism.

In some crank mechanisms, there is a need to ensure the straightness of the piston rod movement 4 . To do this, between the crank 1, connecting rod 2 and slider 5 use a so-called crosshead 3, absorbing the swinging movements of the connecting rod (4 - intermediate rod).

Eccentric mechanism. An eccentric mechanism works similar to a crank-slider mechanism, in which the role of a crank is played by an eccentric mounted on the drive shaft. Cylindrical surface of ex-centric 2 freely covered by a clamp 1 and yoke 3, to which the connecting rod is attached 4, transmitting translational motion to the slider during rotation of the drive shaft 5. Unlike the crank-slider mechanism, the eccentric mechanism cannot convert the reciprocating movement of the slider into the rotational movement of the eccentric due to the fact that between the clamp and the eccentric, despite the presence of lubrication, sufficient friction remains to impede the movement.

For this reason, the eccentric mechanism is used only in those machines where it is necessary to convert rotational motion into reciprocating motion and create a small stroke for the executive body under significant forces. Such machines include stamps, presses, etc.

Crank-rocker mechanism. The rocker arm is a link in the lever mechanism and is a part in the form of a double-armed lever, swinging about the middle fixed axis on the stand. Crank 1 can perform rotational movement. Kinematic chain: crooked spike 1, connecting rod 2 and the rocker arm 3, connected by articulated joints, causes the rocker arm to perform rocking movements around a fixed axis on the stand.

The crank-rocker mechanism is used in spring suspensions of steam locomotives, carriages, in the designs of machines for testing materials, scales, drilling rigs, etc.

1 .4 Rocker mechanism

Backstage 1 - a link (part) of the rocker mechanism, equipped with a straight or arcuate slot in which a small slider moves - rocker stone 2 . Rocker mechanism - a lever mechanism that converts rotational or punitive movements into reciprocating movements and vice versa. According to the type of movement, the scenes are distinguished: rotating, swinging and rectilinearly moving (3 - hole through which the rocker stone is inserted and removed).

Crank mechanism. In Fig. 38, I shows that a crank 3 rotates around a fixed axis, pivotally connected at one end to a slider (rocker stone) 2. In this case, the slider begins to slide (move) in a longitudinal straight groove cut in the lever (slide) 1, and rotate it around a fixed axis. The length of the crank allows you to give the rocker a rotational movement. Such mechanisms serve to convert the uniform rotational movement of the crank into the uneven rotational movement of the rocker, but if the length of the crank is equal to the distance between the axes of the crank and rocker supports, then a crank mechanism with a uniformly rotating rocker is obtained.

The crank mechanism with a swinging rocker (Fig. 38, II) is used to convert the rotational movement of the crank 3 into the rocking movement of the rocker 1 and at the same time there is a fast move when the slider moves in one direction and a slow move in the other. The mechanism is widely used in metal-cutting machines, for example: in cross-planing, gear shaping, etc.

A crank mechanism with a progressively moving rocker (Fig. 38, III) serves to transform the rotational movement of the crank 3 into the rectilinear translational movement of the scenes 1. In the mechanism, the link can be located vertically or obliquely. This mechanism is used for short stroke lengths and is widely used in calculating machines (sine mechanism)

1 .5 Cam mechanism

A cam is a part of a cam mechanism with a profiled sliding surface so that, during its rotational movement, it transmits motion to the associated part (pusher or rod) with a given law of speed change. The geometric shape of the cams can be different: flat, cylindrical, conical, spherical and more complex.

Cam mechanisms are transforming mechanisms that change the nature of movement. In mechanical engineering, cam mechanisms that convert rotary motion into reciprocating and reciprocating motion are widespread. Cam mechanisms (Fig. 39 and 40), like other types of mechanisms, are divided into flat and spatial.

Cam mechanisms are used to perform various operations in control systems for the operating cycle of technological machines, machine tools, engines, etc. The main element of the gas distribution system of an internal combustion engine is the simplest cam mechanism . The mechanism consists of a cam 1, rods 2, connected to the working body, and a rack that supports the links of the mechanism in space and provides each link with the corresponding degrees of freedom. Roller 3, installed in some cases at the end of the rod, does not affect the law of motion of the mechanism links. A rod that moves forward is called a pusher 2, & rotational - rocker 4 . With continuous movement of the cam, the pusher makes an intermittent translational movement, and the rocker arm makes an intermittent rotational movement.

A prerequisite for the normal operation of the cam mechanism is the constant contact of the rod and the cam (closing the mechanism). The closure of the mechanism can be forceful or geometric. In the first case, closure is usually provided by a spring 5 , pressing the rod to the cam, in the second - by the design of the pusher, especially its working surface. For example, a pusher with a flat surface touches the cam at different points, so it is used only when transmitting small forces.

In light industrial machines, to ensure very complex interconnected movement of parts,

In light industry machines, to ensure very complex interconnected movement of parts, along with the simplest flat ones, spatial cam mechanisms are used. In a spatial cam mechanism you can see a typical example of geometric closure - a cylindrical cam with a profile in the form of a groove into which the pusher roller fits.

When choosing the type of cam mechanism, they try to use flat mechanisms, which have a significantly lower cost compared to spatial ones, and in all cases where this is possible, they use a rod of a swinging design, since the rod (rocker arm) is convenient to install on a support using rolling bearings. In addition, in this case, the overall dimensions of the cam and the entire mechanism as a whole may be smaller.

The production of cam mechanisms with conical and spherical cams is a complex technical and technological process, and therefore expensive. Therefore, such cams are used in complex and precise instruments.

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The transformation of rotational motion is carried out by various mechanisms called transmissions. The most common are gear and friction transmissions, as well as flexible transmissions (for example, belt, rope, tape and chain). With the help of these mechanisms, rotational motion is transmitted from the source of motion (drive shaft) to the motion receiver (driven shaft).

Gears are characterized by their gear ratio or gear ratio.

Gear ratio i The ratio of the angular velocity of the driving link to the angular velocity of the driven link is called. The gear ratio can be greater than, less than, or equal to one.

Gear ratio and two conjugate links is called the ratio of the greater coal velocity to the lesser. The gear ratio is always greater than or equal to one.

In order to unify the designations, we will denote the gear ratios and gear ratios of all gears with the letter “and”, in some cases with a double index corresponding to the indices of the transmission links: .

Note that index 1 is assigned to the parameters of the master transmission link, and index 2 to the slave.

A gear in which the angular velocity of the driven link is less than the angular velocity of the driving link is called downward otherwise the transfer is called increasing

In technology, the most widely used are: 1) gear, 2) belt and 3) chain drives.

1. General information about the simplest gears, their main types, as well as the structural elements of gears, racks and worms is known from the drawing course. Let's consider a gear train, shown schematically in Fig. 2.17.

At the point of contact of the gears I And II the speeds of the points of the first and second wheels are the same. Designating the module of this speed v, we get . Therefore, we can write it like this: .

From the drawing course it is known that the diameter of the pitch circle of a gear is equal to the product of its modulus and the number of teeth: d= mz. Then for a pair of gears:

Fig.2.17

2. Consider a belt drive, schematically shown in Fig. 10.6. With absence

Fig.2.18

belt slipping on pulleys ,therefore, for belt drive.

The invention relates to mechanical engineering and can be used as a screw device for converting rotational motion into translational motion. The device consists of a screw (1), a housing (2) with covers (3), threaded rollers (9) that engage with the threads of the screw (1). The threaded rollers (9) are secured against axial displacement relative to the body due to the balls (12) installed in the separators (11), which rest against the covers (3) of the body by means of a spherical undercut (D) made at the ends of each threaded roller, and an annular groove (B ), made on the inner end surface of each cover. Elastic rings (10) have the ability to rotate in the grooves (E) of the threaded rollers (9) relative to the screw axis. To ensure assembly of the device, the width L P of the groove “E” of the threaded rollers was greater than the width L K of the rings by at least 1.5...2 pitches of the screw thread. Two versions of the device are possible, in one of which the threaded rollers are additionally connected to the body by gears, and in the other they are not connected. Favorable kinematics at the points of contact of the ball with the cover and the roller, as well as the ability to roll the rings along the “E” grooves of the threaded rollers, provide high efficiency, low wear rate and high durability. 1 salary f-ly, 3 ill.

The invention relates to mechanical engineering and can be used as a mechanical screw transmission to convert rotational motion into translational motion.

A planetary roller screw gear is known (see Reshetov D.N. “Machine Parts,” a textbook for students of mechanical engineering and mechanical specialties at universities, 4th edition, M.: Mashinostroenie, 1989, p. 314), consisting of a screw, a nut and threaded rollers installed between them. The rollers with their end journals are installed in the separators. To prevent spontaneous unscrewing of the rollers, they are additionally connected at the ends to the nut by gears. The roller turns are in threaded engagement with the screw and nut turns. In this case, the screw has an external multi-start thread, and the nut has an internal multi-start thread.

The main disadvantage of this planetary roller screw is the technological complexity of manufacturing high-precision multi-start threads (usually five or six-start) on the inner surface of the nut, hardened to high hardness. Mainly for this reason, mastering the production of planetary roller screw gears, which in most operational parameters are superior to other gears for converting rotational motion into translational motion, is difficult. In the world, only a few companies have mastered the production of planetary roller screw gears.

In this case, the threaded nut of the planetary roller screw in question performs the following functions:

Receives axial force from the actuator and transmits it through the rollers to the screw;

Keeps the rollers from moving in the radial direction from the screw axis to the nut;

Participates in the transformation of rotational motion into translational motion.

Of the known technical solutions, the closest in technical essence to the claimed device is a device for converting rotational motion into translational motion (see Kozyrev V.V. Designs of roller screws and methods of their design: textbook / Vladimir State University - Vladimir : Editorial and Publishing Complex of VlGU, 2004. pp. 8-9, Fig. 1.7), which was chosen as a prototype. This device consists of a screw, a housing with covers that performs translational motion, threaded rollers that are installed in the housing with the ability to rotate around their own axes, two rings with internal conical chamfers and bearings installed between the rings and covers. On each threaded roller there is a thread cut, the turns of which are in engagement with the turns of the screw, and at the ends there are conical chamfers that interact with the internal conical chamfers of the rings. The device body does not have internal multi-start threads and internal gears, and the threaded rollers do not have external gears. In each bearing, the rolling elements are installed in a cage.

When the device operates, the screw rotates, the threaded rollers rotate only around their own axes (there is no rotational movement of the axes of the threaded roller around the screw axis), and the housing moves translationally along the screw axis. The working axial force of any direction is transmitted from the screw to the threaded rollers due to the engagement of the threads of these parts, from the threaded rollers to the corresponding bushing due to the contact of the conical chamfers of the threaded rollers and the bushing, and from the bushing to the corresponding cover through the corresponding bearing.

This device has the following disadvantages:

The neck of the threaded roller - the hole in the cover forms a plain bearing with low efficiency and high wear rate;

When the threaded roller rotates between its conical chamfers and the mating chamfers of the rings, sliding friction occurs due to different radii of the contact points;

Due to the small contact area between the mating conical chamfers of the threaded rollers and rings, the device has low contact strength, and due to sliding friction in the specified interface, low load capacity and durability;

The device has large radial dimensions;

Threaded rollers rotate only around their own axis, which reduces the transfer function of the device and the range of its change.

The objective of the invention is to increase the efficiency, load capacity and durability of a device for converting rotational motion into translational motion by replacing sliding friction with rolling friction at the interface between the device parts, as well as reducing the radial dimensions and expanding the range of changes in the transfer function of the device.

The task is achieved by the fact that the device is equipped with at least two rings, on the end surfaces of each threaded roller there are turnkey surfaces and spherical undercuts, the centers of which are located on the axis of the threaded roller, and on its cylindrical threaded surface there are ring grooves, the number of which equal to the number of rings, and on the inner end surface of each cover there is an annular groove, the profile of which is an arc of a circle, the rings are installed in the grooves of the threaded rollers, and the number of balls in each row is equal to the number of the last ones, while each ball in each row interacts on one side with spherical undercut of the threaded roller at the corresponding end, on the opposite side - with the annular groove of the corresponding cover, and the width of the annular grooves on the threaded rollers is greater than the width of the rings by at least 1.5...2 pitches of the screw thread. It is possible to design the device for which it is equipped with bushings with internal toothed rims fixed in the housing hole on its different sides, which engage with external gear rims made at the end sections of each threaded roller.

The invention is illustrated by the accompanying drawings, where:

Figure 1 shows a general view of the device;

Figure 2 shows a section A-A in Figure 1 for the 1st version of the device;

Figure 3 shows a section A-A in Figure 1 for the 2nd version of the device with additional gearing between the threaded rollers and the housing bushings.

The device for converting rotational motion into translational motion, see Fig. 1, consists of a screw 1 and a unit that makes translational movement with basic elements “B”, which are designed to connect the specified unit with the actuator. The specified unit, see Fig. 2, consists of a housing 2 and two covers 3, which are connected to the housing with screws 4 with spring washers 5. At least a set of shims or a compensator 6 is installed between one cover 3 and the housing 2. other versions of the specified unit, which ensure the assembly and operation of the device.

An L-shaped sleeve 7 is attached to the outer end surface of each cover 3, see Fig. 2, which holds the oil deflector 8 with axial and radial clearance, and on the inner end surface of the cover there is an annular groove “B”, the profile of which is an arc of a circle.

Inside the housing, see Fig. 2, threaded rollers 9 are installed, the number of which is usually selected from the neighborhood condition to increase the load capacity of the device (the minimum number of threaded rollers is three). The thread turns of the rollers 9 engage with the thread turns of the screw 1. At the ends of each threaded roller 9, see Fig. 2, spherical undercuts “G” are made, the center of which is located on the axis of the threaded roller, and turnkey holes “D”, and on the cylindrical threaded surface - grooves “E”, the number of which is at least two. Spring steel rings 10 are installed in the grooves “E” of the threaded rollers 9, which press the threaded rollers against the screw with low force. In this case, the width L P of the groove “E” is greater than the width L K of ring 10 by 1.5...2 thread pitches of the screw (threaded roller) to ensure assembly of the device.

Between each cover 3 and the threaded roller 9, see Fig. 2, there is one row of balls 12 installed in the separator 11, the number of which is equal to the number of threaded rollers. In this case, each ball 12 interacts on one side with the annular groove “B” of the cover 3, and on the opposite side with the spherical undercut “G” of the threaded roller 9.

In the device described above, the threaded rollers have two degrees of freedom: each roller can rotate around its own axis; all rollers together with separators can rotate relative to the screw axis. Hence, the device can have a non-constant axial movement of the housing with rollers and balls with uniform rotation of the screw (variable transfer function). Devices for converting rotary motion into translational motion with a variable transfer function can be used, for example, in locking mechanisms, jacks, and so on.

In order for the proposed device to have a constant transfer function, additional coupling is required between the threaded rollers and the housing, for example gears. This connection reduces the number of degrees of freedom of the threaded rollers to one. In this case, see Fig. 3, at the ends of each threaded roller 9 there are external gears “W”, and bushings 13 with internal gears “I” are fixed in the hole of the housing 2.

Let us consider, as a general case, the order of assembling a device in which the threaded rollers are additionally connected to the body by gears. The screw usually has a cylindrical “K” surface, which simplifies assembly, see Fig. 3. The right cover 3, see Fig. 3, with a row of balls 12 in the separator 11, is installed on the screw from its left end. Rings 10 are installed in the grooves “E” of the threaded rollers 9, and this unit is inserted from the left end of the screw, see Fig. 3, onto its cylindrical surface “K”. Using a wrench, the threaded rollers are alternately screwed onto the screw until their threads are completely engaged with the threads of the screw. Next, the screw is installed vertically in the fixture, and the base element of the fixture is placed under the cover 3, ensuring that the cover is perpendicular to the axis of the screw. The balls in the separator are installed in the annular groove “B” of the cover. Then, using a wrench, the threaded rollers are alternately screwed onto the screw until the undercut “G” of each roller interacts with the corresponding ball. Since when threaded rollers are screwed into a screw, they occupy different positions along its axis, it is necessary that the width L P of the groove “E” of the threaded rollers be greater than the width L K of rings 10 by at least 1.5...2 pitches of the screw thread. To fix the position of the threaded rollers relative to the screw and the right cover, a second row of balls with a separator is installed on top of the rollers and the assembled assembly is tightened with a special nut, which is screwed onto the screw. Then a housing is installed on top of the specified unit, in which the left sleeve 13 is fixed with an internal gear rim, the teeth of which are engaged with the outer teeth by a roller. The screw with the assembled assembly without the right cover and balls with a separator is removed from the device, and the right bushing 13 with an internal gear rim is inserted into the hole in the housing and onto the teeth of the rollers, and then this bushing is secured in the housing, for example, using a cylindrical pin. On the same side, balls with a separator and a right cover are connected to the rollers, which are connected to the body with a threaded connection. Then, having unscrewed the special nut, screws 4 with spring washers 5 connect the housing to the left cover through a compensator or a set of shims. By measuring the idle torque, it is determined whether the device needs to be adjusted using a compensator or a set of shims.

The device for converting rotational motion into translational motion operates as follows. Screw 1, see Fig. 3, rotating, sets in motion threaded rollers 6, which perform a planetary motion, rolling along the gear rims of bushings 13. The threaded rollers are secured against axial displacement relative to the housing due to balls resting against the housing covers. This is the mechanism for converting the rotational movement of the screw into the translational movement of the housing together with all the parts installed in it. In this case, the balls 12 will roll along the annular grooves “G” of the covers and perform additional rotation relative to the axis of the rollers under the influence of friction forces. Rings 10 will roll along the grooves of the threaded rollers, taking up the radial load from the screw to the rollers. The axial load will be transferred from the housing cover through the balls to the threaded rollers along their axes.

In the inventive device, the working axial force is transmitted from the housing cover directly through the balls to the rollers along their axes, almost like in a thrust bearing. In the prototype device, when transmitting axial force, there is an additional interface that works with sliding friction, and the installation of threaded rollers is carried out on plain bearings. Consequently, the inventive device provides higher efficiency, less wear of contacting surfaces and greater durability. In addition, the threaded rollers in the inventive device undergo planetary motion, for which a larger range of measurement of the transfer function can be obtained.

1. A device for converting rotational motion into translational motion, containing a screw installed in a housing having covers, with the ability to rotate around its own axis, threaded rollers that are threadedly engaged with the screw and on each side with their ends rest against the cover through a series of balls installed in separator, characterized in that the device is equipped with at least two rings, on the end surfaces of each threaded roller there are turnkey surfaces and spherical undercuts, the centers of which are located on the axis of the threaded roller, and on its cylindrical threaded surface there are ring grooves, the number of which equal to the number of rings, and on the inner end surface of each cover there is an annular groove, the profile of which is an arc of a circle, the rings are installed in the grooves of the threaded rollers, and the number of balls in each row is equal to the number of the last ones, while each ball in each row interacts on one side with spherical undercut of the threaded roller at the corresponding end, on the opposite side - with the annular groove of the corresponding cover, and the width of the annular grooves on the threaded rollers is greater than the width of the rings by at least 1.5...2 pitches of the screw thread.

2. The device according to claim 1, characterized in that it is equipped with bushings with internal toothed rims fixed in the housing hole on its different sides, which engage with external gear rims made at the end sections of each threaded roller.

In construction machines, various mechanisms are used to convert rotational motion into other types of motion in order to transfer this motion to the working body.

Rack and pinion mechanism, screw and rocker

In construction machines, various types of motion are used to convert rotational motion into other types of motion in order to transfer this motion to the working body. mechanisms.

Rack and pinion mechanism
Design: drive gear and driven rack.

Used to convert rotational motion into translational motion.
Design: drive screw and driven nut.

Used to convert rotational motion into translational motion.
Design: driving cam and driven rod with spring.

Design: eccentric, connecting rod, slider.

Used to convert rotational motion into reciprocating motion.
Design: drive crankshaft with a curved pin, driven connecting rod, slider.

Used to convert rotational motion into swinging motion of the scenes.
Design: drive disk, slider, driven rocker.
Used in concrete pumps.

Maltese mechanism It is used to convert continuous rotating motion into intermittent rotating motion.
Design: driving disk with lever, driven maltissa.

Ratchet mechanism used to convert rotational motion into intermittent rotational motion, but with stopping and braking.
Design: the driving element is a ratchet, the driven element is a pawl (stopping element).

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: 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 is satisfied 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: 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].

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 thread type retardation mechanism that decelerates rotation like the above-mentioned planetary type retardation 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: 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].

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.

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.

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.