JP2020085184A - Coupling device and driving device - Google Patents

Abstract

To provide a coupling device capable of flexibly absorbing positional deviation in a case when an input rotor is inclined to an output rotor or eccentric thereto, suppressing manufacturing costs, and reducing vibration and noise in operation, and a driving device including the same.SOLUTION: A coupling device constituted by connecting an input rotor 41 and an output rotor 42 rotated on a center shaft as a center, includes an input transmission portion, an output transmission portion, a first coil spring 430 and a second coil spring 440. The input transmission portion is included in the input rotor. The output transmission portion is included in the output rotor. The first coil spring is fixed to the input transmission portion at one end portion, and fixed to the output transmission portion at the other end portion, and its winding direction is a first direction. The second coil spring is fixed to the input transmission portion at one end portion, and fixed to the output transmission portion at the other end portion, and its winding direction is a second direction opposite to the first direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a coupling device and a drive device.

Conventionally, a coupling device that connects an input rotary body and an output rotary body is known. This type of coupling device is used, for example, in an electric motor or a speed reducer. A conventional coupling device is disclosed in, for example, Japanese Patent Laid-Open No. 2004-245269. The joint of the electric motor disclosed in Japanese Unexamined Patent Publication No. 2004-245269 is an Oldham hub fixed to the output shaft of the electric motor, an Oldham hub fixed to the driven shaft, and an Oldham slider that connects two Oldham hubs at right angles to each other. 11) and are provided.
JP, 2004-245269, A

In the case of the Oldham coupling disclosed in Japanese Unexamined Patent Application Publication No. 2004-245269, the Oldham hub and the Oldham slider (11) have a clearance tolerance, which causes tilting or eccentricity of the output shaft with respect to the driven shaft. It is common to adopt a configuration that absorbs the positional deviation. However, when such a configuration is adopted, high processing accuracy is required, which is disadvantageous in that the manufacturing cost increases. In addition, if there is a clearance tolerance, there is room for improvement in that vibration and noise increase due to collision of parts during operation.

The present invention has been made in view of the above circumstances, and its potential object is to cause tilt or eccentricity when the input rotating body is inclined with respect to the output rotating body or when it is eccentric. It is an object of the present invention to provide a coupling device that can flexibly absorb the deviation of the position to be operated, can suppress the manufacturing cost, and can reduce vibration and noise during operation, and a drive device including the same.

The problem to be solved by the present invention is as described above, and the means for solving this problem will be described below.

According to an aspect of the present invention, a coupling device having the following configuration is provided. That is, this coupling device is a coupling device that connects an input rotary body and an output rotary body that rotate about a central axis, and includes an input transmission unit, an output transmission unit, a first coil spring, and a first coil spring. Two coil springs are provided. The input transmission unit is included in the input rotating body. The output transmission unit is included in the output rotating body. One end of the first coil spring is fixed to the input transmission unit and the other end is fixed to the output transmission unit, and the winding direction is the first direction. The second coil spring has one end fixed to the input transmission part and the other end fixed to the output transmission part, and the winding direction is a second direction opposite to the first direction.

According to the aspect of the present invention, when the input rotary body is tilted with respect to the output rotary body, or when it is eccentric, it is possible to flexibly absorb the positional deviation due to the tilt or eccentricity, (EN) Provided are a coupling device and a drive device which can reduce costs and also reduce vibration and noise during operation.

FIG. 1 is a vertical cross-sectional view of a wave gear type speed reducer including a coupling device according to this embodiment. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a diagram showing the configuration of the coupling device, and is a diagram viewed from one side in the axial direction, a partial vertical sectional view, and a vertical sectional view. FIG. 4 is a diagram showing the configuration of the coupling device according to the second embodiment.

Hereinafter, exemplary embodiments of the present application will be described with reference to the drawings. In the present application, the direction parallel to the central axis of the wave gear type speed reducer is "axial direction", the direction orthogonal to the central axis of the wave gear type speed reducer is "radial direction", the central axis of the wave gear type speed reducer is The directions along the arc having the center are referred to as "circumferential direction". Further, in the present application, the “parallel direction” also includes a substantially parallel direction. In addition, in the present application, the “orthogonal direction” also includes a substantially orthogonal direction.

<1. First Embodiment>
<1-1. Overall structure of wave gear type speed reducer>
Hereinafter, the overall configuration of the wave gear type speed reducer 100 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a vertical cross-sectional view of a wave gear type speed reducer 100 including a coupling device 40 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, showing the meshing of the flexible outer teeth and the rigid inner teeth. However, in FIG. 2, hatching is omitted in order to make the drawing easy to see.

The wave gear type speed reducer 100 of the present embodiment is a device that shifts the input rotational power by using a differential (relative rotation) between a rigid internal gear 10 and a flexible external gear 20 described later. is there. The wave gear type speed reducer 100 is, for example, incorporated in a joint of a small robot and is used as a speed reducer for reducing the power obtained from a motor. As shown in FIG. 1, the wave gear type speed reducer 100 includes a rigid internal gear 10, a flexible external gear 20, a wave generator 30, and a coupling device 40.

The rigid internal gear 10 is an annular member centered on the central axis C shown in FIG. Rigidity The rigidity of the internal gear 10 is much higher than the rigidity of the flexible tooth portion 23 of the flexible external gear 20 described later. Therefore, the rigid internal gear 10 can be regarded as a substantially rigid body. The rigid internal gear 10 has a plurality of rigid internal teeth 11 on its inner peripheral surface. As shown in FIG. 2, the plurality of rigid internal teeth 11 are arranged at a constant pitch along the circumferential direction. The rigid internal gear 10 of the present embodiment is fixed to the frame of the device in which the wave gear type speed reducer 100 is mounted.

The flexible external gear 20 is a member including a cylindrical body portion 21 and a flat plate portion 22. The body portion 21 is a portion that can be flexibly deformed in the radial direction. A flat plate portion 22 is connected to an end portion on one side in the axial direction of the cylindrical body portion 21. Further, the cylindrical body portion 21 has a flexible tooth portion 23 having flexible outer teeth 29 formed on the outer peripheral surface at the end portion on the other side in the axial direction.

The flat plate portion 22 is a portion that extends in a substantially planar shape perpendicular to the central axis C. The flat plate portion 22 is less likely to bend and deform than the body portion 21. The flat plate portion 22 has an annular plate-shaped fixing portion 25 and a diaphragm portion 24. The diaphragm portion 24 is arranged on the side closer to the connection portion with the body portion 21, and has a smaller thickness in the axial direction than the fixed portion 25. The diaphragm portion 24 has an annular shape and is less flexible than the flexible tooth portion 23.

The fixed portion 25 is a portion that is disposed inside the diaphragm portion 24 in the radial direction and has a constant wall thickness. The flexibility of the fixed portion 25 is much smaller than that of the diaphragm portion 24. An output shaft (driven shaft, not shown) for extracting power after deceleration is coaxially fixed to the fixed portion 25.

The wave generator 30 is a mechanism for flexibly deforming the flexible tooth portion 23 of the flexible external gear 20 in the radial direction in a non-round shape. The wave generator 30 includes a non-round cam 31 and a wave bearing 33.

The non-round cam 31 of this embodiment is a plate-shaped cam having an elliptical cam profile. As shown in FIG. 1, the non-round cam 31 is arranged radially inward of the flexible tooth portion 23 of the flexible external gear 20. The input shaft (driving shaft) 1 is fixed to the central portion of the non-round cam 31 so as not to be rotatable relative thereto via a coupling device 40 described later. Specifically, this input shaft 1 can be, for example, an output shaft of an electric motor. When the input shaft 1 rotates, the non-round cam 31 rotates about the central axis C at the rotation speed before deceleration, that is, at the same rotation speed as the input shaft 1.

As shown in FIG. 2, the wave bearing 33 has an inner ring 331, a plurality of balls 332, and an elastically deformable outer ring 333. The inner ring 331 is fixed to the outer peripheral surface of the non-round cam 31. The outer ring 333 is fixed to the inner peripheral surface of the flexible tooth portion 23 of the flexible external gear 20. The plurality of balls 332 are interposed between the inner ring 331 and the outer ring 333 and are arranged along the circumferential direction. The outer ring 333 is elastically deformed (flexed) through the inner ring 331 and the balls 332, reflecting the cam profile of the rotated non-round cam 31.

The coupling device 40 is a joint device for connecting the input shaft 1 and the wave generator 30. The coupling device 40 has a substantially cylindrical shape. More specifically, the coupling device 40 connects an input rotary body 41 that rotates about the central axis C and an output rotary body 42 that is arranged coaxially with the input rotary body 41. The input rotating body 41 includes the input shaft 1. The input rotating body 41 rotates at the same rotation speed as the input shaft 1. Therefore, when the input shaft 1 rotates at the first rotation speed, the input rotating body 41 also rotates at the first rotation speed. Then, as described later in detail, the output rotary body 42 also rotates at the same first rotation speed as the input rotary body 41. Here, in the present embodiment, the non-round cam 31 of the wave generator 30 and the rearmost part (output transmission part 420) of the output rotary body 42 are a single member. Therefore, when the input rotary body 41 rotates at the first rotation speed, the non-round cam 31 of the wave generator 30 also rotates at the first rotation speed. The detailed configuration of the coupling device 40 will be described later.

As described above, in the wave gear type speed reducer 100, when the input shaft 1 is supplied with power at the first rotation speed, the non-round cam 31 also rotates at the first rotation speed. Further, as the non-round cam 31 rotates, the inner peripheral surface of the flexible tooth portion 23 of the flexible external gear 20 is pushed via the wave bearing 33, so that the flexible tooth portion 23 is pressed. Deforms in an elliptical shape in the radial direction. As a result, as shown in FIG. 2, the flexible outer teeth 29 and the rigid inner teeth 11 mesh with each other at two locations on both ends of the major axis of the ellipse formed by the flexible tooth portions 23. At this time, the flexible outer teeth 29 and the rigid inner teeth 11 do not mesh with each other at positions other than the above-mentioned two positions on the outer circumference of the ellipse.

When the non-round cam 31 rotates, the position of the major axis of the ellipse moves in the circumferential direction, so that the meshing position between the flexible outer teeth 29 and the rigid inner teeth 11 also moves in the circumferential direction. Here, the number of the rigid internal teeth 11 of the rigid internal gear 10 is slightly different from the number of the flexible external teeth 29 of the flexible external gear 20. Therefore, the meshing position of the rigid inner teeth 11 and the flexible outer teeth 29 slightly changes each time the non-round cam 31 rotates. As a result, the flexible external gear 20 and the output shaft described above rotate with respect to the rigid internal gear 10 at the reduced second rotation speed. Thereby, the decelerated power can be taken out of the device.

Here, in a coupling device such as a joint, it is desirable that the rotation of the input rotary body can always be accurately transmitted to the output rotary body. The same shall apply hereinafter) is required to be small. Further, in order to prevent the function of the coupling device from being impaired even if there is some mounting error, the radial rigidity of the coupling device is required to have some flexibility. Therefore, conventionally, an Oldham joint is known as a joint that can suppress the generation of thrust force to a small extent and can absorb radial mounting errors to some extent. However, in the case of the Oldham coupling, as described above, it is disadvantageous in that the manufacturing cost increases and that vibration and noise during operation increase.

Therefore, it is conceivable to use a coil spring having large flexibility in the radial direction for the joint. Specifically, a configuration is conceivable in which the input rotary body and the output rotary body are connected by a single coil spring. In such a case, the manufacturing cost can be suppressed, and vibration and noise during operation can be reduced. However, such a configuration is disadvantageous in that the coil spring is twisted and the winding diameter is changed according to the direction and magnitude of the torque applied to the joint, which in turn causes thrust force.

<1-2. Detailed configuration of coupling device>
In this respect, the coupling device 40 of the present embodiment has a peculiar configuration, so that reduction of manufacturing cost, reduction of vibration and noise during operation, and suppression of thrust force can be realized. In the following, this particular configuration of the coupling device 40 will be described in detail with reference to FIGS. FIG. 3 shows a view when the coupling device 40 is viewed from one side in the axial direction, a partial vertical sectional view, and a vertical sectional view.

The coupling device 40 has an input transmission part 410, an output transmission part 420, a first coil spring 430, and a second coil spring 440.

The input transmission unit 410 is located at the rearmost stage of the power transmission path of the input rotating body 41. The input transmission part 410 is a cylindrical member extending in the axial direction. A concave portion 411 that is recessed radially inward is provided on the outer peripheral surface of the end portion of the input transmission portion 410 on one side in the axial direction. In addition, a concave portion 412 that is recessed radially inward is provided on the outer peripheral surface of the input transmission portion 410 in the axially intermediate portion.

The output transmission part 420 is located at the most front stage of the power transmission path of the output rotary body 42. The output transmission part 420 is a cylindrical member extending in the axial direction. The output transmission part 420 is arranged radially outward of the input transmission part 410. A gap is provided between the input transmission part 410 and the output transmission part 420 in the radial direction. A concave portion 421 that is recessed radially outward is provided on the inner peripheral surface of the output transmission portion 420 at a midway portion in the axial direction. Further, a concave portion 422 that is recessed radially outward is provided on the inner peripheral surface of the end portion on the other axial side of the output transmission portion 420. The output transmission unit 420 and the non-round cam 31 of this embodiment are a single member.

The first coil spring 430 is a member formed by spirally winding a metal wire. The first coil spring 430 has a natural length of L1, a metal wire thickness of B1, a winding direction of the first direction, and a winding diameter of D1. One end of the metal wire of the first coil spring 430 is engaged with the recess 411 of the input transmission part 410. The other end of the metal wire of the first coil spring 430 is engaged with the recess 421 of the output transmission part 420.

The second coil spring 440 is a member formed by spirally winding a metal wire. The second coil spring 440 has a natural length of L2, a metal wire thickness of B2, a winding direction of the second direction, and a winding diameter of D2. Here, L2 is equal to L1 (L2=L1), B2 is equal to B1 (B2=B1), D2 is equal to D1 (D2=D1), and the second direction is opposite to the first direction. is there. One end of the metal wire of the second coil spring 440 is engaged with the recess 412 of the input transmission part 410. The other end of the metal wire of the second coil spring 440 is engaged with the recess 422 of the output transmission part 420.

Here, the concave portion 412 of the input transmission portion 410 is arranged closer to the other side in the axial direction than the concave portion 421 of the output transmission portion 420. Therefore, the first coil spring 430 and the second coil spring 440 are arranged apart from each other in the axial direction and do not interfere with each other.

In the coupling device 40 having the above-described configuration, it is assumed that the input rotary body 41 is not arranged exactly coaxially with the output rotary body 42 due to an attachment error or the like. Specifically, it is assumed that the input rotary body 41 is eccentric with respect to the output rotary body 42, or the input rotary body 41 is inclined with respect to the output rotary body 42. The operation of each part of the coupling device 40 in such a case will be briefly described below.

When the central axis C of the input rotary body 41 is tilted or eccentric with respect to the central axis of the output rotary body 42, the first coil spring 430 and the second coil spring 440 respectively move in the radial direction. Deflection and deformation. As a result, the positional deviation caused by the inclination or eccentricity of the input rotary body 41 with respect to the output rotary body 42 is absorbed by the deformation of the first coil spring 430 and the second coil spring 440. As a result, the rotation of the input rotary body 41 is accurately transmitted to the output rotary body 42 even if there is some mounting error or the like.

Here, the operation of each part of the coupling device 40 when a load torque is applied to the coupling device 40 will be described.

When a load torque in a certain direction is applied to the coupling device 40, the first coil spring 430 tries to deform in the winding tightening direction, that is, the direction in which the winding diameter decreases. At this time, the first coil spring 430 tries to extend in the axial direction. On the other hand, the second coil spring 440 tends to deform in the unwinding direction, that is, the direction in which the winding diameter increases. At this time, the second coil spring 440 tries to contract in the axial direction. As described above, in the coupling device 40 of the present embodiment, the direction of the force applied to the first coil spring 430 in the axial direction and the direction of the force applied to the second coil spring 440 in the axial direction are opposite to each other. .. As a result, when the coupling device 40 as a whole is seen, the thrust force becomes small. That is, the thrust force generated by the first coil spring 430 and the thrust force generated by the second coil spring 440 cancel each other out, and the thrust force almost disappears as a whole. As a result, the rotation of the input rotary body 41 can be accurately transmitted to the output rotary body 42 at all times.

As described above, the coupling device 40 according to the present embodiment includes the input transmission part 410, the output transmission part 420, the first coil spring 430, and the second coil spring 440. Each of the first coil spring 430 and the second coil spring 440 has one end fixed to the input transmission part 410 and the other end fixed to the output transmission part 420. The winding directions of the first coil spring 430 and the second coil spring 440 are opposite to each other. As a result, even when the input rotary body 41 is tilted with respect to the output rotary body 42 or is eccentric, the positional deviation due to the tilt or eccentricity causes the first coil spring 430 and the second coil spring 430 to move. It is absorbed by the deformation of 440, and the rotation of the input rotary body 41 can be accurately transmitted to the output rotary body 42. Further, by using the coil springs 430 and 440 whose winding directions are opposite to each other in combination, it is possible to suppress the generation of thrust force when a torque is applied. As described above, the coupling device 40 has a small number of parts and has a simple structure, so that the manufacturing cost can be suppressed. Further, since no clearance tolerance is provided between the parts, vibration and noise during operation can be suppressed to a small level.

In addition, the first coil spring 430 and the second coil spring 440 have the same winding diameter (D1=D2), the same thickness of the metal wire (B1=B2), and the same natural length ( L1=L2). Therefore, even when a force in the first twisting direction acts on the coupling device 40 and a force in the second twisting direction opposite to the first twisting direction acts, the torsional rigidity and the thrust rigidity are equalized. It can be a property.

Further, the first coil spring 430 and the second coil spring 440 are different from each other in axial position. As a result, the first coil spring 430 and the second coil spring 440 do not come into contact with each other even when a force is applied in the twisting direction. Therefore, it is less likely that the torsional rigidity will change in a complicated manner.

Further, in the coupling device 40 according to the present embodiment, the input transmission part 410 is arranged radially inward of the metal wire forming the first coil spring 430 and the metal wire forming the second coil spring 440. The output transmission part 420 is arranged radially outward of the metal wire forming the first coil spring 430 and the metal wire forming the second coil spring 440. As a result, the overall axial size of the input transmission part 410, the first coil spring 430, the second coil spring 440, and the output transmission part 420 can be suppressed. As a result, a compact coupling device 40 can be realized.

Further, the speed reducer (drive device) disclosed in the present embodiment is equipped with the coupling device 40. The input rotating body 41 includes an input shaft (drive shaft) 1. The output rotary body 42 is connected to the output shaft (driven shaft) at a stage subsequent to the power transmission path.

<2. Second Embodiment>
In the above embodiment, the first coil spring 430 and the second coil spring 440 each have one end fixed to the input transmission part 410 and the other end fixed to the output transmission part 420. It is not limited to this. Instead of the above, as shown in FIG. 4, the coupling device 400 may include an input transmission unit 450, an output transmission unit 460, and an intermediate transmission unit 470. In that case, the intermediate transmission part 470 is interposed between the input transmission part 450 and the output transmission part 460 in the axial direction. The first coil spring 430 has one end fixed to the input transmission part 450 and the other end fixed to the intermediate transmission part 470. The second coil spring 440 has one end fixed to the intermediate transmission part 470 and the other end fixed to the output transmission part 460. With this configuration, even when the input rotary body 41 is tilted with respect to the output rotary body 42 or is eccentric, the positional deviation due to the tilt or eccentricity causes the first coil spring 430 and The second coil spring 440 is deformed and the intermediate transmission portion 470 is displaced to be absorbed, so that the rotation of the input rotary body 41 can be accurately transmitted to the output rotary body 42. Further, by using the coil springs 430 and 440 whose winding directions are opposite to each other in combination, it is possible to suppress the generation of thrust force when a torque is applied.

<3. Other modifications>
In the above embodiment, the end portions of the coil springs 430 and 440 are engaged with the input transmission portion 210 or the output transmission portion 220 by being fitted into the concave portions 411, 412, 421 and 422. Not limited. Instead of the above, for example, the end portion of the coil spring may be connected to the input transmission portion or the output transmission portion by a method such as welding.

In the above-described embodiment, the coupling device 40 is provided in the speed reducer, particularly the wave gear type speed reducer 100, but the invention is not limited to this. INDUSTRIAL APPLICABILITY The coupling device according to the present invention can be widely applied to various devices such as an electric motor as well as a speed reducer.

Further, the respective elements appearing in the above-described embodiments and modifications may be appropriately combined within a range where no contradiction occurs.

The present application can be used for a coupling device.

1 Input shaft 10 Rigid internal gear 11 Rigid internal tooth 20 Flexible external gear 21 Body part 22 Flat plate part 23 Flexible tooth part 24 Diaphragm part 25 Fixed part 29 Flexible external tooth 30 Wave generator 31 Non-true Circular cam 33 Wave bearing 40 Coupling device 41 Input rotating body 42 Output rotating body 100 Wave gear type speed reducer 210 Input transmission part 220 Output transmission part 331 Inner ring 332 ball 333 Outer ring 400 Coupling device 410 Input transmission part 411 Recess 412 Recess 420 Output Transmission portion 421 Recessed portion 422 Recessed portion 430 First coil spring 430 Coil spring 440 Coil spring 440 Second coil spring 450 Input transmission portion 460 Output transmission portion 470 Intermediate transmission portion C Central axis

Claims (9)

A coupling device for connecting an input rotating body and an output rotating body that rotate about a central axis,
An input transmission unit included in the input rotating body;
An output transmission unit included in the output rotating body,
A first coil spring having one end fixed to the input transmission part and the other end fixed to the output transmission part, and having a winding direction in a first direction;
A second coil spring having one end fixed to the input transmission part and the other end fixed to the output transmission part, the winding direction being a second direction opposite to the first direction;
Coupling device including. The coupling device according to claim 1, wherein the input transmission unit is located at a rearmost stage of a power transmission path of the input rotating body,
The output transmission unit is a coupling device located at the most front stage of the power transmission path of the output rotating body. The coupling device according to claim 1 or 2, wherein
A coupling device in which the winding diameter of the first coil spring and the winding diameter of the second coil spring are equal. The coupling device according to any one of claims 1 to 3, wherein:
The thickness of the metal wire which comprises the said 1st coil spring and the thickness of the metal wire which comprises the said 2nd coil spring are equal, The coupling device. The coupling device according to any one of claims 1 to 4,
A coupling device in which the natural length of the first coil spring and the natural length of the second coil spring are equal. The coupling device according to any one of claims 1 to 5, wherein:
The first coil spring and the second coil spring are different in axial position from each other. The coupling device according to any one of claims 1 to 6, wherein:
The input transmission portion is arranged radially inward of the metal wire forming the first coil spring and the metal wire forming the second coil spring,
The said output transmission part is a coupling apparatus arrange|positioned in the radial direction outer side of the said metal wire which comprises the said 1st coil spring, and the said metal wire which comprises the said 2nd coil spring. A drive device comprising the coupling device according to any one of claims 1 to 7,
The input rotating body extends in the axial direction and includes a drive shaft that is directly or indirectly driven to rotate by the power of an electric motor,
The output rotating body is connected to a driven shaft extending in the axial direction at a stage subsequent to the power transmission path. A coupling device for connecting an input rotating body and an output rotating body that rotate about a central axis,
An input transmission unit located at the rearmost stage of the power transmission path of the input rotating body;
An output transmission unit located at the most front stage of the power transmission path of the output rotating body,
An intermediate transmission portion interposed between the input transmission portion and the output transmission portion in the axial direction,
A first coil spring having one end fixed to the input transmission part and the other end fixed to the intermediate transmission part, and having a winding direction in a first direction;
A second coil spring having one end fixed to the intermediate transmission part and the other end fixed to the output transmission part, the winding direction being a second direction opposite to the first direction;
Coupling device including.

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