JP2021143709A - Reduction gear - Google Patents

Abstract

[Problem] To change the stiffness of a reduction gear. [Solution] A reduction gear (1) has a variable stiffness section (50) that varies the stiffness of the reduction gear (1), and a first internal gear (31G) and an external gear (30) that mesh with each other. The variable stiffness section (50) improves the stiffness of the reduction gear (1) by displacing the first internal gear (31G) toward the external gear (30). [Selected Figure] Figure 1

Description

The present invention relates to a speed reducer.

Conventionally, as a speed reducing device, one used for driving a joint portion of a robot is known (see, for example, Patent Document 1).
In this type of reduction gear, for example, high rigidity is required to suppress vibration when moving, while low rigidity is required to make soft contact when gripping a work, and different rigidity is required depending on the situation. In some cases.

JP-A-2019-97363

The present invention has been made in view of the above circumstances, and an object of the present invention is to change the rigidity of the speed reducer.

The present invention is a speed reducer.
The structure has a variable rigidity portion that changes the rigidity of the reduction gear.

According to the present invention, the rigidity of the speed reducer can be changed.

It is a figure which shows the schematic structure of the robot to which the speed reduction device which concerns on embodiment is applied. (A) is a cross-sectional view of the speed reducer according to the present embodiment, and is a cross-sectional view of (b) and (a) taken along the line AA. It is an enlarged view of the B portion of FIG. 2A, and is a diagram for explaining the configuration and operation of the variable rigidity portion of the embodiment. It is a figure for demonstrating the modification of the variable rigidity part of embodiment. It is a figure for demonstrating the modification of the variable rigidity part of embodiment. It is a figure for demonstrating the modification of the variable rigidity part of embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Robot configuration]
FIG. 1 is a diagram showing a schematic configuration of a robot 100 to which the speed reducing device 1 according to the present embodiment is applied.
As shown in this figure, the speed reducing device 1 according to the present embodiment is incorporated in the joint portion 102 connecting the arms 101 (101a, 101b) of the robot 100, and drives the joint portion 102. The robot 100 is, for example, a collaborative robot that collaborates with a human to perform a predetermined work, and its operation is controlled by the control unit 110. The application of the speed reducer 1 of the present embodiment is not limited to the robot, and can be applied to various uses that have an advantage by changing the rigidity of the speed reducer 1, and may be applied to, for example, a machine tool. ..

[Configuration of speed reducer]
FIG. 2A is a cross-sectional view showing the speed reducer 1 according to the present embodiment, and FIG. 2B is a cross-sectional view taken along the line AA of FIG. 2A.
As shown in FIGS. 2 (a) and 2 (b), the speed reducer 1 is a tubular flexible meshing speed reducer, and has a oscillating body shaft 10, an external gear 30, a first internal gear 31G, and a first gear. The two internal gears 32G, the exciter bearing 12, the casing 33, the first cover 34, and the second cover 35 are provided.

The exciter shaft 10 is a hollow cylindrical shaft that rotates around the rotation shaft O1, and has a non-circular (for example, elliptical) outer shape of a cross section perpendicular to the rotation shaft O1 and a vibrating body 10A. It has shaft portions 10B and 10C provided on both sides in the axial direction of 10A. The ellipse is not limited to a geometrically exact ellipse and includes a substantially ellipse. The shaft portions 10B and 10C are shafts having a circular outer shape in a cross section perpendicular to the rotation shaft O1.
In the following description, the direction along the rotation axis O1 is referred to as "axial direction", the direction perpendicular to the rotation axis O1 is referred to as "diametrical direction", and the rotation direction centered on the rotation axis O1 is referred to as "circumferential direction". Further, in the axial direction, the side (left side in the figure) that outputs the decelerated motion connected to the external driven member to the driven member is called the "output side", and is the side opposite to the output side (the output side). The right side in the figure) is called the "anti-output side".

The external gear 30 is a flexible and cylindrical member centered on the rotating shaft O1, and is provided with teeth on the outer periphery.

The first internal gear 31G and the second internal gear 32G rotate around the exciter shaft 10 about the rotation shaft O1. Of these, the first internal gear 31G is configured by providing internal teeth at the corresponding portion of the inner peripheral portion of the first internal gear member 31. The second internal gear 32G is configured by providing internal teeth at a corresponding portion of the inner peripheral portion of the second internal gear member 32.
The first internal gear 31G and the second internal gear 32G are provided side by side in the axial direction and mesh with the external gear 30. Specifically, the first internal gear 31G meshes with the tooth portion of the external gear 30 on the side opposite to the axial center, and the second internal gear 32G is the axial center of the external gear 30. It meshes with the teeth on the more output side.

The oscillating body bearing 12 is, for example, a roller bearing, and is arranged between the oscillating body 10A and the external gear 30. The oscillating body bearing 12 has a plurality of rolling elements (rollers) 12b and a cage 12c for holding the plurality of rolling elements 12b. The plurality of rolling elements 12b roll with the outer peripheral surface of the exciter 10A and the inner peripheral surface of the external gear 30 as rolling surfaces. The oscillating body bearing 12 may have an inner ring separate from the oscillating body 10A and an outer ring separate from the external gear 30.

Spacer rings 41 and 42 are provided on both sides of the oscillating body bearing 12 and the external gear 30 in the axial direction as regulatory members that abut against them and regulate their axial movement.

The casing 33 is connected to the first internal gear member 31 and covers the outer diameter side of the second internal gear 32G. A main bearing 38 (for example, a ball bearing) is arranged between the casing 33 and the second internal gear member 32, and the casing 33 rotatably supports the second internal gear member 32 via the main bearing 38. ing. Further, when the speed reducing device 1 is incorporated into the mating device (robot 100), the casing 33 and the first internal gear member 31 are attached to a fixing member (arm 101a) different from the driven member (arm 101b) of the mating device. They are connected by co-tightening (see Fig. 1).

The first cover 34 is connected to the first internal gear member 31 and covers the meshing portion between the external gear 30 and the first internal gear 31G from the counter-output side in the axial direction. A first bearing 36 (for example, a ball bearing) is arranged between the first cover 34 and the shaft portion 10B of the exciter shaft 10, and the first cover 34 has the exciter shaft 10 via the first bearing 36. Is rotatably supported.

The second cover 35 is connected to the second internal gear member 32 and covers the meshing portion between the external gear 30 and the second internal gear 32G from the output side in the axial direction. The second cover 35 and the second internal gear member 32 are connected to a driven member (arm 101b of the robot 100) that outputs a decelerated motion (see FIG. 1). A second bearing 37 (for example, a ball bearing) is arranged between the second cover 35 and the shaft portion 10C of the exciter shaft 10, and the second cover 35 has the exciter shaft 10 via the second bearing 37. Is rotatably supported.

[Material of each member]
The material of each member is not particularly limited, but in the present embodiment, it is configured as follows.
The exciter shaft 10, the external gear 30, the casing 33, the first cover 34, the second cover 35, and the spacer rings 41, 42 are made of a metal material such as a steel material. Specifically, for example, the exciter shaft 10 is made of a steel material such as chrome molybdenum steel, the external gear 30 is made of a steel material such as nickel chrome molybdenum steel, and the spacer rings 41 and 42 are made of high carbon chrome. It is composed of steel materials such as bearing steel.
The casing 33, the first cover 34, and the second cover 35 are not limited to those made of metal, and may be made of the same resin as the internal gear member.

The first internal gear member 31 and the second internal gear member 32 are made of resin. Such resins include not only natural resins, but also composite materials such as CFRP (Carbon Fiber Reinforced Plastics), composite materials of resins and other materials, and baking materials (paper baking materials, cloth baking materials, etc.). Can be applied. By making these members made of resin instead of metal, the weight of the speed reducer 1 can be reduced. Further, the self-lubricating property of the material itself can reduce the amount of lubricating oil required for the sliding portion.
Note that these members are not limited to those made of resin, and may be made of a metal such as a steel material or aluminum.

[Variable rigidity part]
The speed reduction device 1 includes a variable rigidity portion 50 that changes the rigidity of the speed reduction device 1.
3 (a) and 3 (b) are enlarged views of the portion B of FIG. 2 (a) for explaining the configuration and operation of the variable rigidity portion 50. In FIG. 3A, the external gear 30 and the first internal gear 31G are drawn separately in the radial direction in order to make it easy to recognize them. In reality, the two are closer in the radial direction than in the state shown in FIG. 3A and overlap (mesh) in the circumferential direction. Further, in FIG. 3B, the deformation of each part is exaggerated for the sake of clarity.
The variable rigidity portion 50 of the present embodiment changes the meshing ratio between the first internal gear 31G and the external gear 30 to change the rigidity of the reduction gear 1 (more specifically, the connection connecting the two arms 101). Rigidity) is changed. The meshing ratio refers to the number of teeth in contact with each other, and is generally counted up to the number after the decimal point.

Specifically, as shown in FIG. 3A, the variable rigidity portion 50 includes a pressure ring 51 and a solenoid (actuator) 52.
The pressure ring 51 is formed in a cylindrical shape and is incorporated on the outer diameter side (diameter outer side) of the first internal gear 31G. More specifically, the first internal gear member 31 has an annular recess 31a that opens on the output side in the axial direction on the outer diameter side of the first internal gear 31G, and the inner diameter side of the recess 31a is inside. It is a cylindrical portion 31b having a first internal gear 31G on the peripheral surface and being cantilevered on the counter-output side. The pressure ring 51 is arranged in the recess 31a so as to be fitted onto the cylindrical portion 31b.
The pressure ring 51 has a storage space 51a inside in which a pressure medium (oil, air, etc.) is sealed. The storage space 51a is located on the outer diameter side of the first internal gear 31G and is formed to be relatively wide in the axial direction. Further, the storage space 51a is provided on the inner diameter side (inside in the radial direction) of the pressure ring 51 so that the inner wall portion 51b on the inner diameter side can be deformed by the pressure in the storage space 51a. It is formed thin.

The solenoid 52 is fixed to the outer diameter side of the pressure ring 51, and a plunger 52a (movable iron core) is inserted into the storage space 51a of the pressure ring 51. This solenoid 52 is an example of the pressure changing unit according to the present invention, and changes the pressure of the pressure medium in the pressure ring 51 (storage space 51a) by driving the plunger 52a. Further, the solenoid 52 is electrically connected to the control unit 110 (see FIG. 1) via a cable 52b taken out through a hole formed in the first internal gear member 31 and the first cover 34 in the axial direction. , The operation is controlled by the control unit 110.

Subsequently, the operation of the variable rigidity portion 50 will be described.
As shown in FIG. 3A, when the solenoid 52 does not push out the plunger 52a, the pressure ring 51 is not deformed, and the first internal gear 31G and the external gear 30 are other deformation factors. Except for, it is in the meshed state according to the design drawing.

In this state, when the solenoid 52 is driven to push the plunger 52a into the storage space 51a of the pressure ring 51, the pressure medium in the storage space 51a is pressurized and pressurized as shown in FIG. 3 (b). The inner wall portion 51b of the ring 51 is deformed toward the inner diameter side. Then, the cylindrical portion 31b of the first internal gear member 31 pressed against the inner wall portion 51b is tilted significantly on the unsupported output side (free end side) with the non-output side (fixed end side) as the fulcrum. And deforms to the inner diameter side. As a result, the first internal gear 31G on the inner peripheral surface of the cylindrical portion 31b is displaced toward the external gear 30, and as a result, the meshing ratio between the first internal gear 31G and the external gear 30 is improved. As a result, the rigidity of the speed reducing device 1, that is, the connecting rigidity of the two arms 101 connected via the speed reducing device 1 is improved.
In this way, by controlling the amount of movement of the plunger 52a (advance / retreat member) by the variable rigidity portion 50, the meshing ratio between the first internal gear 31G and the external gear 30 is changed, and the rigidity of the reduction gear 1 is increased. Can be adjusted.

The specific configuration of the variable rigidity portion 50 of the present embodiment is not particularly limited as long as it can change the meshing ratio between the first internal gear 31G and the external gear 30.
For example, as shown in FIG. 4A, instead of the solenoid 52, a tube 52c communicating with the storage space 51a of the pressure ring 51 is provided, and the amount of the pressure medium supplied to the storage space 51a through the tube 52c is measured. The pressure in the storage space 51a may be changed by controlling. The tube 52c is connected to an external pressure medium supply mechanism (not shown), and the operation of the supply mechanism is controlled by the control unit 110 (see FIG. 1). Further, in this case, as shown in FIG. 4B, a flange portion may be provided on the pressure ring 51, and the tube 52c may be attached to the flange portion.
Alternatively, as shown in FIG. 5A, instead of the solenoid 52, a screw 53 (advancing / retreating member) capable of advancing / retreating is provided in the storage space 51a (the space communicating with the solenoid 52), and a screw is provided with respect to the enclosed pressure medium. The pressure in the storage space 51a may be changed by moving the 53 forward and backward.
Alternatively, as shown in FIG. 5B, a storage space 51a may be provided in the first internal gear member 31, and the pressure in the storage space 51a may be changed to directly displace the first internal gear 31G. ..

Alternatively, as shown in FIG. 6A, the cylindrical portion has a pressure ring 54 having a tapered surface on the outer peripheral surface of the cylindrical portion 31b of the first internal gear member 31 and a tapered surface corresponding to the tapered surface on the inner peripheral surface. The cylindrical portion 31b may be displaced by externally fitting the pressure ring 54 and moving the pressure ring 54 forward and backward in the axial direction.
Alternatively, as shown in FIG. 6B, a clamp ring 55 having a C shape in a plan view is arranged on the outer diameter side of the cylindrical portion 31b of the first internal gear member 31 instead of the pressure ring 51, and this clamp is provided. The cylindrical portion 31b may be displaced by advancing and retreating the bolt 55a that tightens the opening of the ring 55.

[Operation of speed reducer]
Subsequently, the operation of the speed reducer 1 will be described.
When the exciter shaft 10 is rotationally driven by a drive source such as a motor, the motion of the exciter 10A is transmitted to the external gear 30. At this time, the external gear 30 is restricted to a shape along the outer peripheral surface of the exciter 10A, and is bent into an elliptical shape having a long axis portion and a short axis portion when viewed from the axial direction. Further, the external gear 30 meshes with the fixed first internal gear 31G at a long shaft portion. Therefore, the external gear 30 does not rotate at the same rotation speed as the exciting body 10A, and the exciting body 10A rotates relatively inside the external gear 30. Then, with this relative rotation, the external gear 30 bends and deforms so that the major axis position and the minor axis position move in the circumferential direction. The period of this deformation is proportional to the rotation period of the exciter shaft 10.

When the external gear 30 bends and deforms, its long axis position moves, so that the meshing position between the external gear 30 and the first internal gear 31G changes in the rotational direction. Here, for example, assuming that the number of teeth of the external gear 30 is 100 and the number of teeth of the first internal gear 31G is 102, the external gear 30 and the first internal gear 31G are used each time the meshing position goes around. The meshing teeth of the teeth are displaced, which causes the external gear 30 to rotate (rotate). With the above number of teeth, the rotational motion of the exciter shaft 10 is decelerated at a reduction ratio of 100: 2 and transmitted to the external gear 30.

On the other hand, since the external gear 30 also meshes with the second internal gear 32G, the meshing position between the external gear 30 and the second internal gear 32G also changes in the rotation direction due to the rotation of the exciter shaft 10. .. Here, since the number of teeth of the second internal gear 32G and the number of teeth of the external gear 30 are the same, the external gear 30 and the second internal gear 32G do not rotate relatively, and the external gear The rotational motion of 30 is transmitted to the second internal gear 32G with a reduction ratio of 1: 1. As a result, the rotational movement of the exciter shaft 10 is decelerated at a reduction ratio of 100: 2 and transmitted to the second internal gear member 32 and the second cover 35, and this rotational movement is transmitted to the driven member (arm of the robot 100). It is output to 101b).

Here, when the speed reduction device 1 is operated when the robot 100 is driven, the control unit 110 changes the rigidity of the speed reduction device 1 by the variable rigidity unit 50.
Specifically, for example, the control unit 110 increases the rigidity of the speed reducer 1 so as to suppress vibration when the robot 100 moves, and increases the rigidity of the speed reducer 1 so that the robot 100 can come into contact with the work softly. Lower. Alternatively, when the robot 100 is moving, the rigidity of the speed reducing device 1 may be lowered to increase the permissible value for contact (with a person or an object), and when the robot 100 is stopped, the rigidity of the speed reducing device 1 may be increased in order to accurately determine the position.

[Technical effect of this embodiment]
As described above, according to the speed reducer 1 of the present embodiment, the rigidity of the speed reducer 1 can be changed by the variable rigidity unit 50. As a result, it is possible to realize appropriate rigidity according to the operating condition of the driven device.

Further, according to the speed reducing device 1 of the present embodiment, the variable rigidity portion 50 includes a storage space 51a in which the pressure medium is enclosed and a pressure changing unit (solenoid 52) that changes the pressure of the pressure medium in the storage space 51a. have. Then, the variable rigidity portion 50 displaces the first internal gear 31G toward the external gear 30 according to the pressure in the storage space 51a, so that the first internal gear 31G and the external gear 30 mesh with each other. The rigidity of the speed reducer 1 can be preferably changed by changing the rate. In the present embodiment, an example of deforming one gear toward the other gear to improve the rigidity has been described, but the method is not limited as long as the rigidity can be improved, for example, by pressurizing itself. A method of adopting a pressure medium that improves the rigidity of the device may be used.

[others]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
For example, in the above embodiment, the variable rigidity portion 50 is incorporated in the first internal gear member 31 on the non-output side to displace the first internal gear 31G, but the second internal gear member on the output side is displaced. It may be incorporated in 32 to displace the second internal gear 32G. However, since the second internal gear member 32 rotates with respect to the casing, it is better to provide the second internal gear member 32 on the gear that does not rotate with respect to the casing as in the above embodiment, for the connection between the variable rigidity portion and the outside of the device (cable 52b or The tube 52c) is more preferable in that it is easy. The "casing" in this case means a housing component fixed to a fixing member different from the driven member of the mating device, and the first internal gear member 31, the casing 33, and the first one in the above embodiment. Corresponds to the cover 34. In other words, the variable rigidity portion is preferably provided on a member that does not rotate relative to the member to which the other end of the wiring or piping for driving the variable rigidity portion is connected.

Further, the variable rigidity portion according to the present invention may be any one that improves the rigidity of the reduction gear by displacing at least one of the pair of gears that mesh with each other toward the other. Therefore, the variable rigidity portion may displace the external gear, or may displace both the internal gear and the external gear. However, when the pair of gears are made of materials having different Young's modulus from each other as in the above embodiment, it is desirable that the variable rigidity portion displaces the gear having the lower Young's modulus.

Further, in the above embodiment, the variable rigidity portion 50 changes the rigidity by changing the meshing ratio of the gears, but the variable rigidity portion according to the present invention changes the rigidity of the reduction gear. Well, it is not limited to those that change the meshing ratio of gears.
For example, the variable rigidity part is a physical property (those that affect the rigidity, for example, elastic modulus, etc.) of the parts of the speed reducer (those that contribute to the connection rigidity between the two arms of the robot) due to energization, temperature change, application of a magnetic field, etc. May be changed.

Further, the speed reduction device according to the present invention is not limited to the flexure meshing type speed reduction device, and can be suitably applied to other types of speed reduction devices such as an eccentric swing type speed reduction device and a simple planetary gear device. Further, the speed is not limited to the one that decelerates by gears, and for example, a traction drive may be used.
In addition, the details shown in the above-described embodiment can be appropriately changed without departing from the spirit of the invention.

1 Solenoid 10A Expulsor 30 External gear 31 First internal gear member 31a Recess 31b Cylindrical part 31G First internal gear 32 Second internal gear member 32G Second internal gear 33 Casing 50 Variable rigidity part 51 Addition Pressure ring 51a Storage space 51b Inner wall 52 Solenoid 52a Plunger 52b Cable 52c Tube 53 Screw 54 Pressure ring 55 Clamp ring 55a Bolt 100 Robot 101 Arm 102 Joint 110 Control unit O1 Rotating shaft

Claims (10)

It ’s a speed reducer,
It has a variable rigidity portion that changes the rigidity of the reduction gear.
Decelerator. Has a pair of gears that mesh with each other
The variable rigidity portion improves the rigidity by displacing at least one of the pair of gears toward the other gear.
The speed reducer according to claim 1. The variable rigidity portion has a storage portion in which a pressure medium is enclosed and a pressure change portion that changes the pressure of the pressure medium in the storage portion.
The accommodating portion displaces at least one of the gears in response to internal pressure.
The speed reducer according to claim 2. The pressure changing portion changes the pressure by advancing and retreating the advancing / retreating member with respect to the pressure medium enclosed in the accommodating portion.
The speed reducer according to claim 3. The variable rigidity portion is provided on a gear that does not rotate with respect to the casing among the pair of gears.
The speed reducer according to any one of claims 2 to 4. The pair of gears are an internal gear and an external gear.
The variable rigidity portion displaces the internal gear toward the external gear.
The speed reducer according to any one of claims 2 to 5. The variable rigidity portion is arranged on the radial outer side of the internal gear.
The speed reducer according to claim 6. The speed reducer is a flexure meshing speed reducer having a oscillating body in which the external gear is flexed and deformed by the oscillating body.
The speed reducer according to claim 6 or 7. The pair of gears are made of materials having different Young's modulus from each other.
The variable rigidity portion displaces the gear having the lower Young's modulus.
The speed reducer according to any one of claims 2 to 8. The variable rigidity portion has a storage portion in which a pressure medium is enclosed and a pressure changing portion that changes the pressure of the pressure medium in the storage portion.
The speed reducer according to claim 1.

Images