Oscillation type gear mechanism, speed reducer, and robot arm

Abstract

To provide a gear mechanism that is high in gear rigidity, and also has high transmission accuracy.SOLUTION: A gear mechanism 12 comprises: a first gear 1 fixed to a casing 11; a second gear 2 arranged coaxially with the first gear and rotatable relative to the casing; an input shaft 31 provided coaxially with the first gear and the second gear and rotatably around an axis C1; an oscillatory gear 3 arranged opposed to the first gear and the second gear and meshing with the first gear and the second gear at an angle θ; and first elastic members 61, 62 energizing the input shaft toward the first gear. The input shaft has an inclined shaft part 311 inclined to the axis C1. The oscillatory gear is provided rotatably around an axis C2 of the inclined shaft part, and is restricted from moving relative to the inclined shaft part in a direction of the axis C2. The oscillatory gear is pressed against the first gear with the energizing force of the first elastic members.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an oscillating gear mechanism, a reducer using the oscillating gear mechanism, and a robot arm using the reducer. [Background technology]

[0002] In general, in industrial robots, the output of a high-speed, low-torque drive motor is converted to low-speed, high-torque by a reducer and used to drive joints. Various types of reducers are used in industrial robots, including a reducer using an oscillating gear mechanism, which obtains a reduction ratio through the oscillating motion of an oscillating gear. A reducer using an oscillating gear mechanism meshes a fixed gear coaxially mounted on an input shaft with an oscillating gear with a different number of teeth that is rotatably supported by an inclined shaft that rotates integrally with the input shaft at an angle relative to the input shaft, and the oscillating gear is oscillated by the rotation of the input shaft. This oscillating motion and the revolution of the oscillating gear, generated by the difference in the number of teeth, are extracted as output, thereby obtaining an output that is reduced in speed relative to the input shaft (Patent Document 1).

[0003] However, the above-mentioned oscillating gear mechanism has problems such as backlash at the meshing parts of the gears caused by dimensional errors or assembly errors of each component, and a decrease in the transmission accuracy of the rotation angle between the input and output shafts caused by wear on the tooth surfaces due to long-term operation.In response to these problems, Patent Document 1 proposes a configuration that suppresses the decrease in transmission accuracy caused by backlash and wear on the tooth surfaces by urging the oscillating gear toward the fixed gear via the input shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-047796 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in order to increase the reduction ratio of the above-mentioned oscillating gear mechanism, it is necessary to increase the number of gear teeth. This poses a problem of reducing the size of each tooth and reducing the gear rigidity. Therefore, an object of the present invention is to provide an oscillating gear mechanism, a reducer, and a robot arm that have high gear rigidity and high transmission accuracy even at a high reduction ratio. [Means for solving the problem]

[0006] The oscillating gear mechanism according to one embodiment of the present invention comprises: a first gear fixed to a fixed member; a second gear arranged coaxially with the first gear and rotatable relative to the fixed member; a shaft member provided coaxially with the first gear and the second gear and rotatable about a first axis; a swing gear disposed opposite the first gear and the second gear and meshing with the first gear and the second gear at a predetermined inclination angle; a biasing means for biasing the shaft member toward the first gear; An oscillating gear mechanism comprising: the shaft member has an inclined shaft portion inclined with respect to the first axis, the swing gear is rotatably provided around a second axis of the inclined shaft portion, and movement of the swing gear in the direction of the second axis relative to the inclined shaft portion is restricted; The oscillating gear is pressed against the first gear by the biasing force of the biasing means. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an oscillating gear mechanism having high gear rigidity and high transmission accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a robot device according to a first embodiment. [Figure 2] FIG. 1 is a cross-sectional view of a reducer according to a first embodiment. [Figure 3] FIG. 2 is a side view of the gear mechanism according to the first embodiment. [Figure 4] FIG. 6 is a cross-sectional view of a reducer according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment The first embodiment will be described in detail below with reference to the drawings. A schematic configuration of a robot device 150 according to the first embodiment will be described using FIG. 1. FIG. 1 is a perspective view of the robot device 150 according to the first embodiment. The robot device 150 is an industrial robot, and includes an articulated robot 100 that performs tasks such as assembling a workpiece W, a control device 130 that controls the articulated robot 100, and a teaching pendant 140 that can be connected to the control device 130. The articulated robot 100 includes a six-axis articulated robot arm (hereinafter simply referred to as a robot arm) 101 and an end effector 102 connected to the tip of the robot arm 101.

[0010] The robot arm 101 includes a base 103 fixed to a workbench, multiple links 121-126 for transmitting displacement and force, and multiple joints J1-J6 for connecting the multiple links 121-126 so that they can pivot or rotate. Each of the multiple joints J1-J6 includes a drive motor (not shown), an encoder (not shown) for detecting the rotation angle of the drive motor's rotation shaft, and a reducer (transmission) (10, FIG. 2) for reducing the output of the drive motor to increase the drive motor's torque. The drive motor (not shown) and the reducer (10, FIG. 2) form an actuator. The reducer (10, FIG. 2) will be described in detail later.

[0011] The end effector 102 is a robot hand and is equipped with a plurality of gripping jaws 104 for gripping the workpiece W. The end effector 102 also includes a drive motor (not shown) that drives the plurality of gripping jaws 104, an encoder (not shown) that detects the rotation angle of the drive motor, and a reducer (10, FIG. 2) that reduces the output of the drive motor. The end effector 102 also includes a force sensor (not shown) that can detect stress (reaction force) acting on the gripping jaws 104, etc.

[0012] The control device 130 is configured by a computer and is configured to control the articulated robot 100. The computer that constitutes the control device 130 includes, for example, a CPU, RAM for temporarily storing data, ROM for storing programs for controlling each part, and an input / output interface circuit. The control device 130 is configured to supply the required power for operating the drive motor from a power supply main body (not shown) to the drive motor, thereby changing the position and orientation of the robot arm 101 and the end effector 102. A teaching pendant 140 can be connected to the control device 130, and commands for controlling the robot arm 101 and the end effector 102 can be input thereto.

[0013] In the robot device 150 configured as described above, the control device 130 drives the drive motors of the multiple joints J1 to J6 of the robot arm 101 in accordance with input settings, etc., to move or stop the end effector 102 to an arbitrary position and posture. Then, in the arbitrary position and posture, the end effector 102 is caused to grip a workpiece W, a part, etc., while detecting stress acting on the gripping jaws 104 with a force sensor, and a task such as assembling the workpiece W is performed.

[0014] Next, the reducer 10 will be described with reference to Figures 2 and 3. Figure 2 is a cross-sectional view of the reducer 10 according to the first embodiment. Figure 3 is a side view of the gear mechanism 12 according to the first embodiment. As shown in Figure 2, the reducer 10 includes a casing 11 as a fixed member and a gear mechanism (oscillating gear mechanism) 12 consisting of a set of oscillating gear mechanisms. The casing 11 is composed of a casing portion 13 and a casing component 14. The casing portion 13 and the casing component 14 are firmly connected by connecting members such as screws (not shown). The casing 11 is formed integrally with or separately from the first gear 1. The first gear 1 is a fixed gear fixed to the casing portion 13.

[0015] The gear mechanism 12 includes an input shaft (first shaft) 31, a first gear 1, a second gear 2, and an oscillating gear 3. The input shaft 31 is a shaft member connected to a rotating shaft of a drive motor (not shown). The input shaft 31 is an input unit to which the rotation of the drive motor (not shown) is input, but the input unit may be provided separately from the input shaft 31. The input shaft 31 is rotatably supported coaxially with the first gear 1 and the second gear 2. The input shaft 31 is rotatably supported around an axis (first axis) C1 by the first gear 1 via a bearing 52, for example, a rolling bearing, and by the second gear 2 via a bearing 53. The input shaft 31 has an inclined shaft portion 311 inclined at an angle θ with respect to the axis C1. That is, an axis (second axis) C2, which is the center line of the inclined shaft portion 311, is inclined at an angle θ with respect to the axis C1, which is the center line of the input shaft 31.

[0016] The first gear 1 has an annular shape coaxial with the axis C1. As shown in FIG. 3 , teeth 41 with a tooth number Z1 are provided at the tip of the annular shape of the first gear 1 in the direction of the axis C1 and point to one side in the direction of the axis C1. The second gear 2 is arranged coaxially with the first gear 1 and is rotatable with respect to the casing 11. The second gear 2 has an annular shape coaxial with the first gear 1. Teeth 42 with a tooth number Z2 are provided at the tip of the annular shape of the second gear 2 in the direction of the axis C1 and point to the other side in the direction of the axis C1. The first gear 1 and the second gear 2 are arranged opposite each other so that the teeth 41 of the first gear 1 and the teeth 42 of the second gear 2 face each other. The oscillating gear 3 is arranged between the first gear 1 and the second gear 2.

[0017] As shown in Fig. 2, the second gear 2 has a flange portion 21. The flange portions 21 of the multiple reducers 10 are connected to the multiple links 121, 122, 123, 124, 125, and 126, respectively. The flange portion 21 is an output portion that reduces the rotation input from the input shaft 31 and outputs it, but the output portion may be provided separately from the flange portion 21. The second gear 2 is supported rotatably about the axis C1 relative to the casing part 14 via a bearing 54, for example, a rolling bearing, so as to be coaxial with the input shaft 31.

[0018] The oscillating gear 3 is disposed opposite the first gear 1 and the second gear 2 and meshes with the first gear 1 and the second gear 2 at a predetermined inclination angle (angle θ in the first embodiment). The oscillating gear 3 is disposed between the first gear 1 and the second gear 2 and is rotatably mounted on the inclined shaft portion 311 via bearings 55 and 56, which are, for example, rolling bearings. The oscillating gear 3 is rotatably mounted around the axis C2 of the inclined shaft portion 311, and its movement in the direction of the axis C2 relative to the inclined shaft portion 311 is restricted. The oscillating gear 3 has an annular shape, and tooth surfaces are formed on both sides of the annular shape. As shown in FIG. 3 , the oscillating gear 3 has first teeth 43 on one side of the annular shape that mesh with teeth 41 of the first gear 1 and second teeth 44 on the other side of the annular shape that mesh with teeth 42 of the second gear 2. The number of teeth of the first teeth 43 is Z3, and the number of teeth of the second teeth 44 is Z4. In the first embodiment, the number of teeth Z1 of the teeth 41 of the first gear 1, the number of teeth Z2 of the teeth 42 of the second gear 2, the number of teeth Z3 of the first teeth 43 of the oscillating gear 3, and the number of teeth Z4 of the second teeth 44 are set to satisfy the relationship Z3 = Z1 + 1 and Z4 = Z2 + 1. Note that the number of teeth Z1 of the first gear 1 and the number of teeth Z2 of the second gear 2 may be different or the same.

[0019] The deceleration operation of the reducer 10 having the gear mechanism 12 described above will now be described. Rotation input from a drive motor (not shown) is transmitted to the inclined shaft portion 311 via the input shaft 31, causing the oscillating gear 3 to oscillate. The oscillating gear 3 revolves 360° / (Z1+1) per oscillation relative to the fixed first gear 1. Meanwhile, an orbital revolution due to the oscillation also occurs between the second gear 2 and the oscillating gear 3. The difference between these revolutions is output from the flange portion 21 of the second gear 2. It is known that the reduction ratio of this type can be calculated by 1-(Z1(Z2+1)) / ((Z1+1)Z2). For example, when Z1=14 and Z2=20, a reduction ratio of 1 / 50 is obtained. Furthermore, for example, if Z1 = 48 and Z2 = 49, a large reduction ratio of 1 / 2401 is possible. This type of reducer can achieve a wide range of reduction ratios in a single stage, from a low reduction ratio of about 1 / 20 to a large reduction ratio of several thousandths. Furthermore, compared to a comparative example in which the revolution of the oscillating gear 3 is extracted as output, the number of teeth can be reduced at the same reduction ratio. For example, when the reduction ratio is 1 / 50, the maximum number of teeth Z4 in the first embodiment is 21, whereas the maximum number of teeth in the comparative example in which the revolution of the oscillating gear is extracted as output is 50. In other words, for the same size and reduction ratio, the number of teeth in the first embodiment is smaller than that in the comparative example, and therefore the size per tooth of the gear in the first embodiment is larger, enabling increased rigidity.

[0020] The input shaft 31 is biased in the direction D1 relative to the bearing 53 by first elastic members (first biasing means) 61, 62, for example, made of disc springs. The first elastic members 61, 62 bias the input shaft 31 toward the first gear 1. The biasing force of the first elastic members 61, 62 biases the oscillating gear 3 in a direction toward the first gear 1. In other words, backlash fluctuation between the first gear 1 and the oscillating gear 3 is minimized, resulting in a gear mechanism 12 with small lost motion, a high meshing ratio, and high transmission efficiency. Furthermore, a reaction force from this biasing force biases the inner ring 531 of the bearing 53 in the direction D2 relative to the outer ring 532. This reaction force closes the gaps between the inner ring 531 and the rolling elements 533 and between the outer ring 532 and the rolling elements 533, improving rotational accuracy. This effect is expected to improve rotational transmission accuracy.

[0021] Inner ring (inner ring portion) 521 of bearing (bearing member) 52 is urged in the direction D1 by second elastic members (second urging means) 63, 64, such as disc springs, supported on spring seat 312 provided on input shaft 31. The urging forces of second elastic members 63, 64 urge inner ring 521 in the direction D1 relative to outer ring (outer ring portion) 522, thereby reducing gaps between inner ring 521 and rolling elements 523 and between outer ring 522 and rolling elements 523, improving rotation accuracy. This effect is expected to improve rotation transmission accuracy.

[0022] The second gear 2 is biased in the direction D1 relative to the bearing 54 by third elastic members (third biasing means) 65, 66, such as disc springs. The third elastic members 65, 66 bias the second gear 2 toward the oscillating gear 3. The biasing forces of the third elastic members 65, 66 bias the second gear 2 in a direction toward the oscillating gear 3. In other words, backlash fluctuation between the second gear 2 and the oscillating gear 3 is minimized, resulting in a gear mechanism 12 with small lost motion, a high meshing ratio, and high transmission efficiency. Furthermore, a reaction force from this biasing force biases the inner ring 541 of the bearing 54 in the direction D2 relative to the outer ring 542. This reaction force closes the gaps between the inner ring 541 and the rolling element 543 and between the outer ring 542 and the rolling element 543, improving rotational accuracy. This effect is expected to improve rotational transmission accuracy.

[0023] Here, the biasing force F1 by the first elastic members 61 and 62, the biasing force F2 by the second elastic members 63 and 64, and the biasing force F3 by the third elastic members 65 and 66 are set so as to satisfy the relationship F3>F1>F2. According to this relationship, for example, the biasing force F3 is greater than the biasing force F1, so the second gear 2 is biased in a direction to contact the oscillating gear 3. Similarly, the biasing force F2 is smaller than the biasing force F1, so the oscillating gear 3 is biased in a direction to contact the first gear 1.

[0024] According to the first embodiment, as the oscillating gear 3 oscillates, a difference between the revolution of the oscillating gear 3 relative to the first gear 1 as a fixed gear and the revolution of the second gear 2 as an output gear relative to the oscillating gear 3 is output. Therefore, a large reduction ratio can be obtained with a small number of teeth, making it possible to realize an oscillating gear mechanism with a large tooth and high rigidity even with a high reduction ratio. Furthermore, because the oscillating gear 3 is pressed against the first gear 1 by the first elastic members 61 and 62, a decrease in transmission accuracy due to backlash and tooth surface wear is suppressed, making it possible to realize an oscillating gear mechanism with high transmission accuracy. In the first embodiment, the reducer 10 has one gear mechanism 12, but the first embodiment is not limited thereto. The reducer 10 may have multiple gear mechanisms. According to the first embodiment, it is possible to provide a gear mechanism 12, a reducer 10, and a robot arm 101 in which the rigidity of the first gear 1, the second gear 2, and the oscillating gear 3 is high and transmission accuracy is high.

[0025] Second Embodiment Next, a second embodiment will be described with reference to Fig. 1 and Fig. 4. A robot device 150 according to the second embodiment is similar to the robot device 150 according to the first embodiment, except that it includes a reducer 10A that is different from the reducer 10 of the first embodiment. Therefore, the following description will focus on the differences from the first embodiment, i.e., the reducer 10A, and the same components as those in the first embodiment will be denoted by the same reference numerals and will not be described again.

[0026] 1, a robot device 150 includes an articulated robot 100 that performs tasks such as assembling a workpiece W, a control device 130, and a teaching pendant 140. The articulated robot 100 includes a six-axis robot arm 101 and an end effector 102. The robot arm 101 includes a base 103, multiple links 121-126, and multiple joints J1-J6. Each of the multiple joints J1-J6 includes a drive motor (not shown), an encoder (not shown), and a reducer (transmission) 10A.

[0027] Next, a reducer 10A according to a second embodiment will be described with reference to FIG. 4. FIG. 4 is a cross-sectional view of the reducer 10A according to the second embodiment. As shown in FIG. 4, the reducer 10A includes a casing 11A as a fixed member and a gear mechanism (oscillating gear mechanism) 12A consisting of a set of oscillating gear mechanisms. The casing 11A is composed of a casing portion 13A and a casing component 14A. The casing portion 13A and the casing component 14A are firmly connected by connecting members such as screws (not shown). The casing portion 13A is formed integrally with or separately from the first gear 1A. The first gear 1A is a fixed gear fixed to the casing portion 13A.

[0028] The gear mechanism 12A includes an input shaft (first shaft) 31A, a first gear 1A, a second gear 2A, and an oscillating gear 3A. The input shaft 31A is a shaft member connected to a rotating shaft of a drive motor (not shown). The input shaft 31A is an input portion to which the rotation of the drive motor (not shown) is input, but the input portion may be provided separately from the input shaft 31A. The input shaft 31A is rotatably supported coaxially with the first gear 1A and the second gear 2A. The input shaft 31A is rotatably supported around an axis (first axis) C1A by the casing 11A via a bearing 52A, for example, a rolling bearing, and by the second gear 2A via a bearing 53A. The input shaft 31A has an inclined shaft portion 311A ​​inclined at an angle θA with respect to the axis C1A. That is, an axis (second axis) C2A, which is the center line of the inclined shaft portion 311A, is inclined at an angle θA with respect to an axis C1A, which is the center line of the input shaft 31A.

[0029] The first gear 1A has an annular shape coaxial with the axis C1A. As shown in FIG. 4, teeth 41A with a number of teeth Z1A are provided at the tip of the annular shape of the first gear 1A in the direction of the axis C1A and point to one side in the direction of the axis C1A. The second gear 2A is arranged coaxially with the first gear 1A and is rotatable with respect to the casing 11A. The second gear 2A is arranged facing the same direction as the first gear 1A. The second gear 2A has an annular shape coaxial with the first gear 1A. Teeth 42A with a number of teeth Z2A are provided at the tip of the annular shape of the second gear 2A in the direction of the axis C1A and point to the same direction as the teeth 41A of the first gear 1A.

[0030] As shown in Fig. 4, the second gear 2A has a flange portion 21A. The flange portions 21A of the multiple reducers 10A are connected to multiple links 121, 122, 123, 124, 125, and 126, respectively. The flange portion 21A is an output portion that reduces the rotation input from the input shaft 31A and outputs it, but the output portion may be provided separately from the flange portion 21A. The second gear 2A is supported coaxially with the input shaft 31A by a bearing 54A, for example, a rolling bearing, relative to the casing portion 13A of the first gear 1A so as to be rotatable about an axis C1A.

[0031] The oscillating gear 3A is disposed opposite the first gear 1A and the second gear 2A and meshes with the first gear 1A and the second gear 2A at a predetermined inclination angle (angle θA in the second embodiment). The oscillating gear 3A is disposed on one side of the first gear 1A and the second gear 2A and is rotatably mounted on the inclined shaft portion 311A ​​via a bearing 55A, which may be, for example, a rolling bearing. The oscillating gear 3A is rotatable about the axis C2A of the inclined shaft portion 311A, and its movement in the direction of the axis C2A relative to the inclined shaft portion 311A ​​is restricted. The oscillating gear 3A has two coaxial annular shapes. The oscillating gear 3A has first teeth 43A at the tip of the outer annular shape that mesh with the teeth 41A of the first gear 1A, and second teeth 44A at the tip of the inner annular shape that mesh with the teeth 42A of the second gear 2A. That is, the oscillating gear 3A has two tooth surfaces formed in a concentric ring shape on the same surface. In the second embodiment, the number of teeth Z1A of the teeth 41A of the first gear 1A, the number of teeth Z2A of the teeth 42A of the second gear 2A, the number of teeth Z3A of the first teeth 43A of the oscillating gear 3A, and the number of teeth Z4A of the second teeth 44A are set to satisfy the relationships Z3A = Z1A + 1 and Z4A = Z2A + 1. Note that the number of teeth Z1A of the first gear 1A and the number of teeth Z2A of the second gear 2A may be different or the same.

[0032] The deceleration operation of the reducer 10A having the gear mechanism 12A described above will now be described. Rotation input from a drive motor (not shown) is transmitted to the inclined shaft portion 311A ​​via the input shaft 31A, causing the oscillating gear 3A to oscillate. The oscillating gear 3A revolves 360° / (Z1A+1) per oscillation relative to the fixed first gear 1A. Meanwhile, an orbital revolution due to the oscillation also occurs between the second gear 2A and the oscillating gear 3A. The difference between these orbital revolutions is output from the flange portion 21A of the second gear 2A. It is known that the reduction ratio of this type can be calculated as 1-(Z1A(Z2A+1)) / ((Z1A+1)Z2A). For example, when Z1A=14 and Z2A=20, a reduction ratio of 1 / 50 is obtained. Furthermore, for example, if Z1A = 48 and Z2A = 49, a large reduction ratio of 1 / 2401 is possible. This type of reducer can achieve a wide range of reduction ratios in a single stage, from a low reduction ratio of about 1 / 20 to a large reduction ratio of several thousandths. Furthermore, compared to the comparative example in which the revolution of the oscillating gear is extracted as output, the number of teeth can be reduced for the same reduction ratio. For example, when the reduction ratio is 1 / 50, the maximum number of teeth Z4 in the second embodiment is 21, whereas the maximum number of teeth in the comparative example in which the revolution of the oscillating gear is extracted as output is 50. In other words, for the same size and reduction ratio, the number of teeth in the second embodiment is smaller than that in the comparative example, and therefore the size per tooth of the gear in the second embodiment is larger, enabling increased rigidity.

[0033] The input shaft 31A is biased in the D1A direction relative to the bearing 52A by first elastic members (first biasing means) 61A and 62A, which are, for example, disc springs. The first elastic members 61A and 62A bias the input shaft 31A toward the first gear 1A. The biasing forces of the first elastic members 61A and 62A bias the oscillating gear 3A in a direction that brings it into contact with the first gear 1A. In other words, backlash fluctuation between the first gear 1A and the oscillating gear 3A is minimized, resulting in a gear mechanism 12A with small lost motion, a high meshing ratio, and high transmission efficiency. Furthermore, a reaction force to this biasing force biases the inner ring 521A of the bearing 52A in the D2A direction relative to the outer ring 522A. This reaction force reduces the gaps between the inner ring 521A and the rolling elements 523A and between the outer ring 522A and the rolling elements 523A, improving rotational accuracy. This effect is expected to improve the precision of rotation transmission.

[0034] Inner ring (inner ring portion) 531A of bearing (bearing member) 53A is urged in the D1A direction by second elastic members (second urging means) 63A, 64A, such as disc springs, supported on spring seat 312A provided on input shaft 31A. The urging forces of second elastic members 63A, 64A urge inner ring 531A in the D1A direction relative to outer ring (outer ring portion) 532A, thereby reducing gaps between inner ring 531A and rolling element 533A and between outer ring 532A and rolling element 533A, improving rotation accuracy. This effect is expected to improve rotation transmission accuracy.

[0035] The second gear 2A is biased in the D2A direction relative to the bearing 54A by third elastic members (third biasing means) 65A, 66A, such as disc springs. The third elastic members 65A, 66A bias the second gear 2A toward the oscillating gear 3A. The biasing forces of the third elastic members 65A, 66A bias the second gear 2A in a direction toward the oscillating gear 3A. This minimizes backlash fluctuation between the second gear 2A and the oscillating gear 3A, resulting in a gear mechanism 12A with small lost motion, a high meshing ratio, and high transmission efficiency. Furthermore, a reaction force to this biasing force biases the inner ring 541A of the bearing 54A in the D1A direction relative to the outer ring 542A. This reaction force reduces the gaps between the inner ring 541A and the rolling elements 543A and between the outer ring 542A and the rolling elements 543A, improving rotational accuracy. This effect is expected to improve the precision of rotation transmission.

[0036] Here, the biasing force F1A by the first elastic members 61A and 62A, the biasing force F2A by the second elastic members 63A and 64A, and the biasing force F3A by the third elastic members 65A and 66A are set so that the relationship F1A > F3A > F2A is satisfied. According to this relationship, for example, because the biasing force F2A is smaller than the biasing force F3A, the second gear 2A is biased in a direction toward contact with the oscillating gear 3A. Similarly, because the biasing force F3A is smaller than the biasing force F1A, the oscillating gear 3A is biased in a direction toward contact with the first gear 1A.

[0037] In the second embodiment, the reducer 10A has one gear mechanism 12A, but the second embodiment is not limited to this, and the reducer 10A may have multiple gear mechanisms. The reducer 10A only needs to have one or more oscillating gear mechanisms. According to the second embodiment, it is possible to provide the gear mechanism 12A, reducer 10A, and robot arm 101 in which the rigidity of the first gear 1, the second gear 2, and the oscillating gear 3 is high and transmission accuracy is high.

[0038] It should be noted that the functions, materials, shapes, numbers and relative positions of the components described in the first and second embodiments are not intended to limit the scope of the present invention to those unless otherwise specified.

[0039] (Configuration 1) A first gear fixed to a fixed member, a second gear arranged coaxially with the first gear and rotatable relative to the fixed member, a shaft member arranged coaxially with the first gear and the second gear and rotatable about a first axis, a swing gear arranged opposite the first gear and the second gear and meshing with the first gear and the second gear at a predetermined inclination angle, and a biasing means for biasing the shaft member toward the first gear. wherein the shaft member has an inclined shaft portion inclined with respect to the first axis line, the oscillating gear is provided rotatably around a second axis line of the inclined shaft portion and is restricted in movement in the direction of the second axis line with respect to the inclined shaft portion, and the oscillating gear is pressed against the first gear by the biasing force of the biasing means. (Configuration 2) The oscillating gear mechanism according to configuration 1, wherein the first gear and the second gear are disposed opposite each other. (Configuration 3) The oscillating gear mechanism according to configuration 2, wherein the oscillating gear is disposed between the first gear and the second gear. (Configuration 4) The oscillating gear mechanism according to configuration 1, wherein the first gear and the second gear are arranged facing in the same direction. (Configuration 5) The oscillating gear mechanism according to configuration 4, wherein the oscillating gear is disposed on one side of the first gear and the second gear. (Configuration 6) An oscillating gear mechanism according to any one of Configurations 1 to 5, further comprising: a bearing member having an inner ring portion and an outer ring portion, the bearing member supporting the shaft member with the inner ring portion; and second biasing means for biasing the inner ring portion relative to the outer ring portion in the direction of the first axis, wherein if the biasing means is referred to as first biasing means, the biasing force of the second biasing means is smaller than the biasing force of the first biasing means. (Configuration 7) An oscillating gear mechanism according to Configuration 2 or 3, comprising: a bearing member having an inner ring portion and an outer ring portion, the bearing member supporting the shaft member with the inner ring portion; second biasing means for biasing the inner ring portion relative to the outer ring portion in the direction of the first axis; and third biasing means for biasing the second gear toward the oscillating gear, wherein, when the biasing means is referred to as a first biasing means, the biasing force of the second biasing means is smaller than the biasing force of the first biasing means, and the biasing force of the third biasing means is larger than the biasing force of the first biasing means. (Configuration 8) An oscillating gear mechanism according to Configuration 4 or 5, comprising: a bearing member having an inner ring portion and an outer ring portion, the bearing member supporting the shaft member with the inner ring portion; second biasing means for biasing the inner ring portion in the direction of the first axis relative to the outer ring portion; and third biasing means for biasing the second gear toward the oscillating gear, wherein the biasing force of the second biasing means is smaller than the biasing force of the third biasing means, and when the biasing means is defined as a first biasing means, the biasing force of the third biasing means is smaller than the biasing force of the first biasing means. (Configuration 9) A reducer comprising one or more oscillating gear mechanisms according to any one of configurations 1 to 8, for reducing the speed of input rotation and outputting it. (Configuration 10) A multi-joint robot arm in which an actuator having a drive motor and the reducer according to Configuration 9 connected to the drive motor is attached to at least one joint. [Explanation of symbols]

[0040] 1...First gear 2...Second gear 3...Oscillating gear 11...Casing 12...Gear mechanism 31...Input shaft 61, 62...First elastic member 311…Incline shaft part C1, C2…axis line θ…Angle

Claims

1. a first gear fixed to a fixed member; a second gear arranged coaxially with the first gear and rotatable relative to the fixed member; a shaft member provided coaxially with the first gear and the second gear and rotatable about a first axis; a swing gear disposed opposite the first gear and the second gear and meshing with the first gear and the second gear at a predetermined inclination angle; a biasing means for biasing the shaft member toward the first gear; An oscillating gear mechanism comprising: the shaft member has an inclined shaft portion inclined with respect to the first axis, the swing gear is rotatably provided around a second axis of the inclined shaft portion, and movement of the swing gear in a direction of the second axis relative to the inclined shaft portion is restricted, The oscillating gear mechanism is characterized in that the oscillating gear is pressed against the first gear by the biasing force of the biasing means.

2. 2. The oscillating gear mechanism according to claim 1, wherein the first gear and the second gear are disposed opposite to each other.

3. 3. The oscillating gear mechanism according to claim 2, wherein the oscillating gear is disposed between the first gear and the second gear.

4. 2. The oscillating gear mechanism according to claim 1, wherein the first gear and the second gear are arranged facing in the same direction.

5. 5. The oscillating gear mechanism according to claim 4, wherein the oscillating gear is disposed on one side of the first gear and the second gear.

6. a bearing member having an inner ring portion and an outer ring portion, the bearing member supporting the shaft member at the inner ring portion; a second biasing means for biasing the inner ring portion relative to the outer ring portion in the direction of the first axis; Further provided with 6. The oscillating gear mechanism according to claim 1, wherein when the biasing means is defined as a first biasing means, the biasing force of the second biasing means is smaller than the biasing force of the first biasing means.

7. a bearing member having an inner ring portion and an outer ring portion, the bearing member supporting the shaft member at the inner ring portion; a second biasing means for biasing the inner ring portion relative to the outer ring portion in the direction of the first axis; a third biasing means for biasing the second gear toward the swing gear; Equipped with When the biasing means is a first biasing means, the biasing force of the second biasing means is smaller than the biasing force of the first biasing means, 4. The oscillating gear mechanism according to claim 2, wherein the biasing force of the third biasing means is greater than the biasing force of the first biasing means.

8. a bearing member having an inner ring portion and an outer ring portion, the bearing member supporting the shaft member at the inner ring portion; a second biasing means for biasing the inner ring portion relative to the outer ring portion in the direction of the first axis; a third biasing means for biasing the second gear toward the swing gear; Equipped with the biasing force of the second biasing means is smaller than the biasing force of the third biasing means; 6. The oscillating gear mechanism according to claim 4, wherein when the biasing means is defined as a first biasing means, the biasing force of the third biasing means is smaller than the biasing force of the first biasing means.

9. A reducer comprising one or more oscillating gear mechanisms according to any one of claims 1 to 5, for reducing and outputting input rotation.

10. 10. A multi-joint robot arm, comprising: an actuator attached to at least one joint; the actuator having a drive motor and the reducer according to claim 9 connected to the drive motor.

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