Drive device of robot arm, horizontal articulated robot, and speed reducer of motor

Abstract

A drive device 150A of a robot arm 120 comprises a motor 160, a motor holder 260, and a speed reducer 210 that decelerates the motor 160 to rotate the robot arm 120. The speed reducer 210 is a wave gear type comprising a wave generator 220 coupled to the motor, a flexspline 230, a first circular spline 240S, a second circular spline 240D, and a bearing 250. The number of teeth of the first circular spline 240S is greater than the number of teeth of the flexspline 230, and the number of teeth of the second circular spline 240D is the same as the number of teeth of the flexspline 230. The first circular spline 240S and the second circular spline 240D are located on the outer peripheral part of the flexspline 230, and are arranged in the order of the first circular spline 240S and the second circular spline 240D when viewed from a support member 110 side of the robot arm 120 in the axial direction of the wave generator 220. The bearing 250 comprises a fixed ring and a movable ring, and is disposed between the first circular spline 240S and the support member 110. The fixed ring of the bearing 250 and the flexspline 230 are fixed to the support member 110, and the first circular spline 240S is fixed to the movable ring of the bearing 250. The robot arm 120 is fixed to the first circular spline 240S, and the motor holder 260 is fixed to the second circular spline 240D. The motor holder 260 is located within a shaft hole of the robot arm 120 and is supported by the robot arm 120 via a bearing 270. The motor 160 is fixed to the motor holder 260, and is positioned outside the support member 110.

Description

Robot arm drive unit, horizontal articulated robot and motor reducer

[0001] The technology disclosed in this specification relates to a drive device for a robot arm.

[0002] Japanese Patent Application Laid-Open No. 2003-144994 discloses a support structure for a first axis motor of a horizontal articulated robot (SCARA robot).

[0003] Patent Document 1 discloses the use of an eccentric oscillating reducer such as an RV reducer as the reducer for the first axis motor of a SCARA robot. Patent Document 1 improves heat dissipation by placing the first axis motor above the base.

[0004] WO2023 / 062776 publication

[0005] An object of the present invention is to improve the heat dissipation of a motor used in a joint of a robot arm.

[0006] (1) A drive device for a robot arm rotatably supported on a support member, the drive device including a motor, a motor holder, and a reducer that reduces the speed of the motor to rotate the robot arm, the reducer being a wave gear type that includes a wave generator coupled to the motor, a flexspline, a first circular spline, a second circular spline, and a bearing, the number of teeth of the first circular spline being greater than the number of teeth of the flexspline, and the number of teeth of the second circular spline being the same as the number of teeth of the flexspline.

[0007] The first circular spline and the second circular spline are located on the outer periphery of the flexspline and are arranged in the axial direction of the wave generator, viewed from the support member side, in this order: the first circular spline, the second circular spline. The bearing has a fixed ring and a movable ring and is arranged between the first circular spline and the support member. The fixed ring and the flexspline of the bearing are fixed to the support member, and the first circular spline is fixed to the movable ring of the bearing. The robot arm is fixed to the first circular spline, and the motor holder is fixed to the second circular spline. The motor holder is located in an axial hole of the robot arm and is supported by the robot arm via a bearing. The motor is fixed to the motor holder and is located outside the support member.

[0008] (2) A drive device for a robot arm rotatably supported on a support member, the drive device including a motor, a motor holder, and a reducer that reduces the speed of the motor to rotate the robot arm, the reducer being a strain wave gear type including a wave generator, a flexspline, a first circular spline, a second circular spline, a third circular spline, and a bearing, wherein the number of teeth of the first circular spline is greater than the number of teeth of the flexspline, and the number of teeth of the second circular spline and the number of teeth of the third circular spline are the same as the number of teeth of the flexspline.

[0009] The first circular spline, the second circular spline, and the third circular spline are arranged on the outer periphery of the flexspline in the axial direction of the wave generator, as viewed from the support member, in the order of the third circular spline, the first circular spline, and the second circular spline. The third circular spline is fixed to the support member, and the third circular spline supports the first circular spline via a bearing. The robot arm is fixed to the first circular spline, and the motor holder is fixed to the second circular spline. The motor holder is located within an axial hole of the robot arm and is supported by the robot arm via a bearing. The motor is fixed to the motor holder and is located outside the support member.

[0010] (3) A drive device for a robot arm rotatably supported on a support member, comprising: a motor; a motor holder; a reducer that reduces the speed of the motor to rotate the robot arm; and a fixed member, wherein the reducer is a wave gear type that includes a wave generator, a flexspline, a first circular spline, and a bearing, and the number of teeth of the first circular spline is greater than the number of teeth of the flexspline.

[0011] The bearing includes a fixed ring and a movable ring and is disposed between the first circular spline and the support member, with the fixed ring and the flexspline of the bearing fixed to the support member. The first circular spline is fixed to the movable ring of the bearing, and the robot arm is fixed to the first circular spline. The motor holder is located within an axial hole of the robot arm and is supported by the robot arm via a bearing. The fixing member fixes the motor holder to the support member, and the motor is fixed to the motor holder and located outside the support member.

[0012] (4) A drive device for a robot arm rotatably supported on a support member, comprising: a motor, a first motor holder, a second motor holder, a reducer that reduces the speed of the motor to rotate the robot arm, and a fixed member, wherein the reducer is a wave gear type that includes a wave generator, a flexspline, a first circular spline, and a bearing, and the number of teeth of the first circular spline is greater than the number of teeth of the flexspline.

[0013] The bearing includes a fixed ring and a movable ring and is disposed between the first circular spline and the support member, the fixed ring and the flexspline of the bearing being fixed to the support member, and the first circular spline being fixed to the movable ring of the bearing. The robot arm and a second motor holder are fixed to the first circular spline. The second motor holder supports the first motor holder via a bearing. The fixing member fixes the first motor holder to the support member. The motor is fixed to the motor holder and is located outside the support member.

[0014] (5) A drive device for a robot arm rotatably supported on a support member, the drive device comprising: a motor, a motor holder, a reducer that reduces the speed of the motor to rotate the robot arm, and a fixed member. The reducer is an eccentric oscillating differential reducer that includes a cylindrical gear case, an internal gear integrally formed on the inner periphery of the gear case, two planetary gears located inside the gear case and meshing with the internal gear, a crankshaft that passes through the gear case and the two planetary gears and is connected to the motor, a carrier that is coaxially supported on the gear case via bearings, and a carrier pin that is attached to the carrier and passes through the two planetary gears.

[0015] The carrier is fixed to the support member, the robot arm is fixed to the gear case, the fixing member fixes the motor holder to the support member, and the motor is fixed to the motor holder and located outside the support member.

[0016] The driving devices (1) to (5) can be applied to a horizontal articulated robot.

[0017] The technology disclosed in this specification can improve the heat dissipation of motors used in the joints of robot arms.

[0018] 12A sectional view of a wave gear reducerExploded perspective view of a wave gear reducerCross-section view of a wave gear reducerSide view of a horizontal articulated robotPlan view of a horizontal articulated robotBlock diagram of a horizontal articulated robotCross-section view of the first jointCross-section view of the first jointCross-section view of a standard type A wave gear reducerCross-section view of a standard type B wave gear reducerCross-section view of a standard type C wave gear reducerCross-section view of the first jointCross-section view of the first jointEnlarged view of a portion (portion D) of FIG. 12APerspective view of a motor, motor holder, and reducerCross-section view of the first jointCross-section view of a wave gear reducerCross-section view of a wave gear reducerCross-section view of a wave gear reducerCross-section view of a wave gear reducer

[0019] <Embodiment 1> 1. Wave gear reducer Fig. 1 is a perspective view of a wave gear reducer, Fig. 2 is an exploded perspective view of the wave gear reducer, and Fig. 3 is a cross-sectional view of the wave gear reducer.

[0020] The strain wave gear reducer 10 is sometimes called a Harmonic Drive (registered trademark). The strain wave gear reducer 10 includes a wave generator 20, a flexspline 30, a first circular spline 40S, and a second circular spline 40D.

[0021] The wave generator 20 consists of an elliptical cam 21 and a ball bearing 23. The ball bearing 23 is located on the outer periphery of the cam 21. The wave generator 20 is fixed to a motor shaft and rotates when driven by the motor. The wave generator 20 is a wave generator.

[0022] The flexspline 30 is made of a flexible metal material. The flexspline 30 is cylindrical with the central axis L of the wave generator 20 as its center. The wave generator 20 is located on the inner periphery of the flexspline 30. The flexspline 30 has external teeth 31 on its outer periphery. The flexspline 30 is a flexible external gear.

[0023] The first circular spline 40S is made of metal (rigidity) and has an annular shape centered on the central axis L of the wave generator 20. The first circular spline 40S has internal teeth 41 on its inner peripheral surface. The second circular spline 40D has a similar configuration.

[0024] The two circular splines 40S, 40D are located on the outer periphery of the flexspline 30 and are aligned in the direction of the central axis L of the wave generator 20. The internal teeth 41 of the circular splines 40S, 40D mesh with the external teeth 31 of the flexspline 30. The circular splines 40S, 40D are rigid external gears.

[0025] The wave generator 20 rotates around the central axis L due to the rotation of the motor. As the wave generator 20 rotates, the flexspline 30 elastically deforms and rotates while partially meshing with the internal teeth 41 of the first circular spline 40S and the second circular spline 40D.

[0026] The number of teeth of the internal teeth 41 of the first circular spline 40S is two more than the number of teeth of the external teeth 31 of the flexspline 30. Due to this difference in the number of teeth, the rotation of the motor can be decelerated and extracted.

[0027] For example, if the first circular spline 40S is fixed, the rotation of the motor can be reduced and taken out from the flexspline 30 or the second circular spline 40D.

[0028] Furthermore, when the flexspline 30 or the second circular spline 40D is fixed, the rotation of the motor can be reduced and taken out from the first circular spline 40S.

[0029] 1 and 2 show a ring-type flexspline 30, but other types include a top hat type (FIG. 7) and a cup type (FIG. 8). The top hat type has an attachment portion (flange 235) formed outward, while the cup type has an attachment portion (diaphragm 335) formed inward. The basic structure and operation of the strain wave gear reducers 210, 310, 410, and 510 disclosed below are the same as those of the strain wave gear reducer 10.

[0030] 2. Configuration of the horizontal articulated robot Figure 4 is a side view of the horizontal articulated robot, and Figure 5 is a plan view of the horizontal articulated robot. The horizontal articulated robot 100 is sometimes called a SCARA robot. The horizontal articulated robot 100 is a robot whose arms move horizontally, and includes a base 110, a first arm 120, a second arm 130, a work axis 145, and a cover 140.

[0031] The base 110 is made of, for example, metal and is box-shaped having an upper wall 110A, a lower wall 110B, and an outer wall 110C.

[0032] The first arm 120 is, for example, made of metal and has a hollow shape, is attached to the base 110, and is rotatable in the horizontal direction. The second arm 130 is, for example, made of metal, is attached to the tip of the first arm 120, and is rotatable in the horizontal direction. The first arm 120 is an example of a "robot arm" in the present invention, and the base 110 is an example of a "support member" in the present invention.

[0033] The work shaft 145 is attached to the tip of the second arm 130. The work shaft 145 is capable of rotation around its axis and movement in the vertical direction. An end effector (not shown) is attached to the tip of the work shaft 145. The end effector is a general term for a tip tool selected depending on the application of the robot, and examples include a gripper (robot hand) and a welding torch.

[0034] 6 is a block diagram of the horizontal articulated robot 100. The horizontal articulated robot 100 includes a motor control board 115, a first axis motor 160, a second axis motor 170, a third axis motor 180, and a fourth axis motor 190.

[0035] The first axis motor 160 is attached to a first joint J1 (a joint between the base 110 and the first arm 120) of the horizontal articulated robot 100. The first axis motor 160 is used to drive the first arm 120.

[0036] The second axis motor 170 is attached to the second joint J2 (the joint between the first arm 120 and the second arm 130) of the horizontal articulated robot 100. The second axis motor 170 is used to drive the second arm 130.

[0037] The third axis motor 180 and the fourth axis motor 190 are attached to the second arm 130 of the horizontal articulated robot 100. The third axis motor 180 is used to move the working axis 145 up and down, and the fourth axis motor 190 is used to rotate the working axis 145.

[0038] 7 is a cross-sectional view (cross-sectional view taken along line A-A in FIG. 5) of the first joint J1 of the horizontal articulated robot 100. The drive unit 150A of the first arm 120 is used to operate the first joint J1, and includes a first axis motor 160, a motor holder 260, a bearing 270, a bearing presser 280, and a strain wave gear reducer 210.

[0039] The motor holder 260 is made of, for example, metal and is composed of a cylindrical peripheral wall portion 261 and a bottom wall portion 263. The bottom wall portion 263 is located at the lower end of the peripheral wall portion 261 and protrudes inward. The motor holder 260 is positioned in the shaft hole 125 of the first arm 120.

[0040] A bearing 270 is disposed between the shaft hole 125 of the first arm 120 and the motor holder 260. The motor holder 260 is supported by the first arm 120 via the bearing 270.

[0041] The first shaft motor 160 is composed of a motor body 161 and a motor shaft 163. The first shaft motor 160 is fixed to the motor holder 260 with a bolt B1, with the motor body 161 protruding upward from the shaft hole 125 of the first arm 120.

[0042] A motor cable 165 of the first axis motor 160 is led into the base 110 via a capacitive touch panel.

[0043] The strain wave gear reducer 210 is located in the shaft hole 215 of the first arm 120 and is attached to the tip of the motor shaft 163. The strain wave gear reducer 210 functions to reduce the speed of rotation of the first shaft motor 160 and increase the torque.

[0044] As shown in FIG. 7 , the strain wave gear reducer 210 includes a wave generator 220 , a flexspline 230 , a first circular spline 240S, a second circular spline 240D, and a bearing 250 .

[0045] The wave generator 220 is positioned in the shaft hole 125 of the first arm 120. The motor shaft 163 of the first shaft motor 160 is coupled to the wave generator 220 by a key 167.

[0046] The flexspline 230 is located on the outer periphery of the wave generator 220. The first circular spline 240S and the second circular spline 240D are located on the outer periphery of the flexspline 230 and are aligned in the direction of the central axis L of the wave generator 220 (the up-down direction).

[0047] In this example, the first circular spline 240S and the second circular spline 240D are arranged in this order when viewed from the side of the base 110. In other words, the first circular spline 240S is arranged on the bottom and the second circular spline 240D is arranged on the top.

[0048] The second circular spline 240D is located below the motor holder 260 and is fixed to the motor holder 260 with a bolt B2.

[0049] The bearing 250 is made up of an inner ring 251, an outer ring 252, and a cross roller 253. The bearing 250 is disposed below the first circular spline 240S. In this example, the inner ring 251 is a movable ring, and the outer ring 252 is a fixed ring.

[0050] The flexspline 230 is of a so-called top hat type and has a cylindrical main body 231 and a flange 235 at one end (the lower end in this example) of the main body 231. External teeth that mesh with the internal teeth of the circular splines 240S, 240D are provided on the outer periphery of the main body 231. The flange 235 protrudes outward from the main body 231. The flange 235 is annular.

[0051] The flexspline 230 and the outer ring (fixed ring) 252 of the bearing 250 are fixed to the upper wall 110A of the base 110 with bolts B3.

[0052] The first circular spline 240S is fixed to the inner ring (movable ring) 251 of the bearing 250 with a bolt B4. The first circular spline 240S also has an attachment portion 245. The attachment portion 245 protrudes outward in the radial direction more than the second circular spline 240D. The attachment portion 245 is located below the first arm 120 and is fixed to the first arm 120 with a bolt B5.

[0053] The bearing holder 280 is fixed to the first arm 120 with a bolt B6. The bearing holder 280 has a contact portion 281 that contacts the bearing 270, and functions to fix the bearing 270 and prevent it from loosening.

[0054] Oil seal 290 is annular and is disposed between motor holder 260 and bearing retainer 280. Oil seal 290 seals the gap between motor holder 260 and bearing retainer 280, and prevents lubricating oil from reducer 210 from leaking to the outside.

[0055] When the first shaft motor 160 is driven, its power is transmitted to the first arm 120 while being reduced in speed by the harmonic gear reducer 210. Therefore, by driving the first shaft motor 160, the first arm 120 can be rotated in the horizontal direction around the axis L.

[0056] The first shaft motor 160 and the motor holder 260 are fixed to the second circular spline 240D. The number of teeth of the internal teeth 41 of the second circular spline 240D is equal to the number of teeth of the external teeth 31 of the flexspline 230.

[0057] Therefore, during motor rotation, the second circular spline 240D remains stationary, as does the flexspline 230 fixed to the base 110, and therefore the first axis motor 160 and motor holder 260 also remain stationary.

[0058] 4. Effects (1) The strain wave gear reducer 210 is available in a wide range of sizes, from small to large, and can therefore be used with a wide range of horizontal articulated robots 100, from small to large.

[0059] (2) The first-axis motor 160 is located outside the base 110 (on the top in the first embodiment), which allows for cooling by natural convection, improving cooling performance. The improved cooling performance allows for an increased operating duty of the first-axis motor 160.

[0060] (3) Since the first axis motor 160 does not move relative to the base 110, movement of the motor cable 165 caused by motor driving can be suppressed. In this example, the motor cable 165 can be easily retracted relative to the base 110.

[0061] (4) There is no need to provide a space for accommodating the first-axis motor 160 within the base 110, which allows for a larger wiring space within the base. In addition, the shape of the base 110 can be simplified, which is advantageous for reducing costs.

[0062] Second Embodiment In a driving device 150A of the first embodiment, an inner ring 251 of a bearing 250 is a movable ring, and an outer ring 252 is a fixed ring. In a driving device 150B of the second embodiment, an inner ring 351 of a bearing 350 is a fixed ring, and an outer ring is a movable ring.

[0063] 8, the strain wave gear reducer 310 includes a wave generator 320, a flexspline 330, a first circular spline 340S, a second circular spline 340D, and a bearing 350. The bearing 350 is located between the first circular spline 340S and the base 110, and includes an inner ring 351, an outer ring 352, and cross rollers 353.

[0064] The flexspline 330 is a so-called cup type, and has a cylindrical main body 331 and a diaphragm 335 below the main body 331 .

[0065] The diaphragm 335 protrudes inward from an end (the lower end in this example) of the main body 331. The diaphragm 335 is located on the upper surface of the inner ring 351 of the bearing 350 and is fixed to the inner ring 351 with bolts B7. The inner ring 351 is also fixed to the upper wall 110A of the base 110 with bolts B8.

[0066] The first circular spline 340S is fixed to the outer ring 352 of the bearing 350 by a bolt B9.

[0067] The first circular spline 340S also has an attachment portion 345. The attachment portion 345 protrudes radially outward more than the second circular spline 340D. The attachment portion 345 is located below the first arm 120 and is fixed to the first arm 120 with a bolt B5.

[0068] Like the drive device 150A of embodiment 1, the drive device 150B of embodiment 2 allows the first axis motor 160 to be placed outside the base 110, and can achieve the effects of (1) to (4).

[0069] Third Embodiment The driving device 150A of the first embodiment uses a strain wave gear reducer 210 to reduce the speed of the first shaft motor 160. The driving device 150C of the third embodiment uses a strain wave gear reducer 410 to reduce the speed of the first shaft motor 160.

[0070] As shown in FIG. 9, the strain wave gear reducer 410 differs from the strain wave gear reducer 210 of the first embodiment in that a third circular spline 440E is provided.

[0071] Specifically, the strain wave gear reducer 410 includes a wave generator 420, a flexspline 430, a first circular spline 440S, a second circular spline 440D, and a third circular spline 440E.

[0072] The first circular spline 440S, the second circular spline 440D, and the third circular spline 440E are located on the outer periphery of the flexspline 430 and are aligned in the direction of the central axis L of the wave generator 420 (the up-down direction).

[0073] In this example, the third circular spline 440E, the first circular spline 440S, and the second circular spline 440D are arranged in this order when viewed from the side of the base 110. In other words, the second circular spline 440D is arranged above the first circular spline 440S, and the third circular spline 440E is arranged below the first circular spline 440S.

[0074] The first circular spline 440S, the second circular spline 440D, and the third circular spline 440E each have internal teeth 41. The internal teeth 41 of the first circular spline 440S, the internal teeth 41 of the second circular spline 440D, and the internal teeth 41 of the third circular spline 440E mesh with the external teeth 31 of the frame spline 430, respectively.

[0075] The number of teeth on the internal teeth 41 of the first circular spline 440S is two more than the number of teeth on the external teeth 31 of the flexspline 430. The number of teeth on the internal teeth 41 of the second circular spline 440D and the number of teeth on the internal teeth 41 of the third circular spline 440E are the same as the number of teeth on the external teeth 31 of the flexspline 430.

[0076] The second circular spline 440D is located below the motor holder 260 and is fixed to the motor holder 260 with a bolt B2.

[0077] The first circular spline 440S has an attachment portion 445. The attachment portion 445 protrudes radially outward more than the second circular spline 440D. The attachment portion 445 is located at the bottom of the first arm 120 and is fixed to the first arm 120 with a bolt B5.

[0078] The first circular spline 440S also has an annular protrusion 447 that protrudes downward. The third circular spline 440E is located inside the protrusion 447 of the first circular spline 440S. A bearing (e.g., a cross roller) 450 is provided between the third circular spline 440E and the protrusion 447. The third circular spline 440E is rotatable relative to the first circular spline 440S. The third circular spline 440E is fixed to the top wall 110A of the base 110 with bolts B10.

[0079] In the driving device 150C of the third embodiment, the strain wave gear reducer 410 can be made flat, and the height of the first arm 120 can be reduced.

[0080] Like the drive device 150A of embodiment 1, the drive device 150C of embodiment 3 allows the first axis motor 160 to be placed outside the base 110, and can achieve the effects of (1) to (4).

[0081] 10A to 10C show the structures of strain wave gear reducers 510A to 510C of standard types A to C. Standard types A to C refer to products that have been commercialized by manufacturers and are distributed on the market.

[0082] As shown in FIG. 10A , the standard type A strain wave gear reducer 510A includes a wave generator 520A, a flexspline 530A, a first circular spline 540S, and a bearing 550A. The flexspline 530A is of a so-called top hat type and includes a cylindrical main body 531A and a flange 535A at one end (the lower end in this example) of the main body 531A. The flange 535A protrudes outward from the main body 531A. The bearing 550A includes an inner ring 551A, an outer ring 552A, and a cross roller 553A.

[0083] The standard type A has a specification in which the inner ring 551A of the bearing 550A is a movable ring and the outer ring 552A is a fixed ring, with the first circular spline 540S fixed to the inner ring 551A and the flexspline 530A fixed to the outer ring 552A.

[0084] As shown in FIG. 10B , the standard type B strain wave gear reducer 510B includes a wave generator 520B, a flexspline 530B, a first circular spline 540S, and a bearing 550B. The flexspline 530B is a so-called cup-shaped tubular main body 531B and includes a diaphragm 535B at the end (the lower end in this example) of the main body 531B. The diaphragm 535B protrudes inward from the main body 531B. The bearing 550B includes an inner ring 551B, an outer ring 552B, and a cross roller 553B.

[0085] The standard type B has a specification in which the inner ring 551B of the bearing 550B is a fixed ring and the outer ring 552B is a movable ring, and the flexspline 530B is fixed to the inner ring 551B and the first circular spline 540S is fixed to the outer ring 552B.

[0086] 10C, the standard type C strain wave gear reducer 510C has a wave generator 520C, a flexspline 530C, a first circular spline 540S, and a second circular spline 540D. The standard type C does not have bearings.

[0087] The driving device 150D of the fourth embodiment employs a structure in which a fixing member 570 is used to prevent rotation of the motor body 161, and as shown in FIG. 11, a standard type A strain wave gear reducer 510A can be used.

[0088] Specifically, the strain wave gear reducer 510A has a wave generator 520A, a flexspline 530A, a first circular spline 540S, and a bearing 550A.

[0089] The flexspline 530A is fixed to the upper wall 110A of the base 110 together with the outer ring 552A by bolts B3.

[0090] The first circular spline 540S is fixed to the first arm 120 and the inner ring 551A of the bearing 550 by bolts B5.

[0091] The motor holder 560 is located inside the shaft hole 125 of the first arm 120. A bearing 270 is disposed between the shaft hole 125 of the first arm 120 and the motor holder 560. The motor holder 560 is supported by the first arm 120 via the bearing 270.

[0092] The fixing member 570 is a member that prevents the motor body 161 of the first shaft motor 160 from rotating. The fixing member 570 includes a first member 571 and a second member 575.

[0093] The first member 571 has a shape that is long in the vertical direction, and is located on the top wall 110A of the base 110 to the side of the first arm 120 (to the right in FIG. 11 ). The first member 571 is fixed to the top wall 110A of the base 110 with a bolt B11.

[0094] The second member 575 is located near the upper end of the first member 571 and is fixed to the first member 571 with a bolt B12. The second member 575 extends horizontally toward the motor holder 560. The second member 575 is fixed to the upper end of the motor holder 560 with a bolt B13. In addition, a cable clamp 576 for holding the motor cable 165 is installed on the second member 575.

[0095] By fixing the motor holder 560 to the base 110 via the fixing member 570, the motor body 161 can be prevented from rotating.

[0096] The driving device 150D of the fourth embodiment has the advantage that it can use the strain wave gear reducer 510A of standard type A. Similarly, strain wave gear reducers 510B and 510C can also be used.

[0097] In addition to the above, the drive unit 150D of embodiment 4, like the drive unit 150A of embodiment 1, is capable of placing the first axis motor 160 outside the base 110, thereby achieving the effects of (1) to (4).

[0098] <Embodiment 5> The drive device 150E of embodiment 5 employs a structure that uses a fixing member 690 to prevent the motor body 161 from rotating, similar to the drive device 150D of embodiment 4, and uses a standard type A strain wave gear reducer 510A, similar to the drive device 150D of embodiment 4.

[0099] 12A shows a drive unit 150E of embodiment 5. Drive unit 150E of embodiment 5 differs from drive unit 150D of embodiment 4 in the structure of a motor holder 660. Specifically, motor holder 660 is divided into a first motor holder 661 and a second motor holder 665.

[0100] The second motor holder 665 is located above the first circular spline 540S. The first arm 120 is fixed to the second motor holder 665 with a bolt B16. The second motor holder 665 and the first circular spline 540S are fixed to the inner ring 551A of the bearing 550A with a bolt B15.

[0101] The first motor holder 661 is located above the second motor holder 665. The motor main body 161 is fixed to the first motor holder 661. A cylindrical first peripheral wall 662 is provided on the first motor holder 661, and a second peripheral wall 666 is provided on the second motor holder 665. The two peripheral walls 662, 666 are located above the wave generator 520A and are coaxial with the motor shaft 163.

[0102] The second peripheral wall 666 is located on the outer periphery of the first peripheral wall 662. Two bearings 670 are arranged one above the other between the two peripheral walls 662, 666. The two motor holders 661, 665 are rotatable relative to one another. Also, reference numeral 675 in FIG. 12A denotes a bearing holder, and reference numeral 680 denotes an oil seal.

[0103] 12B is an enlarged view of a portion (area D: the area surrounding the bearing) of FIG. 12A. A spacer 663 is positioned between the inner rings of two bearings 670, and a protrusion 668 of a second peripheral wall 666 is positioned between the outer rings.

[0104] 13, the drive unit 150E of the fifth embodiment allows the first shaft motor 160, motor holder 660, and strain wave gear reducer 510A to be handled as a single unit, which has the advantage of being easy to assemble.

[0105] In addition to the above, the drive unit 150E of embodiment 5, like the drive unit 150A of embodiment 1, is capable of placing the first axis motor 160 outside the base 110, thereby achieving the effects of (1) to (4).

[0106] Sixth Embodiment A drive device 150F of a sixth embodiment differs from the drive device 150D of the fourth embodiment in that the strain wave gear reducer 510A is replaced with an eccentric oscillating type differential reducer 710.

[0107] 14 shows a drive unit 150F of embodiment 6. An eccentric oscillating type differential reducer 710 includes a gear case 720, an internal gear 730, two planetary gears 740, a crankshaft 750, two carriers 770A and 770B, a carrier pin 775, and a bearing (an angular bearing, for example) 780.

[0108] The gear case 720 is cylindrical. An internal gear 730 is integrally formed on the inner periphery of the gear case 720. The two planetary gears 740 are disk-shaped and have a shaft hole in the center. The two planetary gears 740 are aligned in the axial direction of the gear case 720 (top and bottom in Figure 14). The two planetary gears 740 have external teeth on their outer peripheries. The external teeth of the two planetary gears 740 mesh with the internal gear 730. The external teeth of the two planetary gears 740 are 180° out of phase with each other.

[0109] The crankshaft 750 passes through the gear case 720 and the two planetary gears 740. The crankshaft 750 is coupled to a motor shaft 163 of the first shaft motor 160.

[0110] Carriers 770A and 770B are disk-shaped and are disposed on both ends of gear case 720. Carriers 770A and 770B are coaxially supported on gear case 720 via bearings 780. Carrier pins 775 are fixed to carriers 770A and 770B and pass through two planetary gears 740. Driving unit 150F can extract rotation from carrier 770 by reducing the speed of first shaft motor 160.

[0111] In this example, the carrier 770B is fixed to the top wall 110A of the base 110 with a bolt B21, and the gear case 720 is fixed to the first arm 120 with a bolt B22. Note that in this example, the carriers 770A and 770B are provided on both sides of the gear case 720, but they may be provided on only one side.

[0112] The drive unit 150F of embodiment 6, like the drive units 150A to 150E of embodiments 1 to 5, allows the first axis motor 160 to be placed outside the base 110, and can achieve the effects (1) to (4) of embodiments 1 to 5.

[0113] Seventh Embodiment In the first embodiment, a strain wave gear reducer 210 is used as the reducer of the first shaft motor 160. As shown in Fig. 15 , the strain wave gear reducer 210 includes a wave generator 220, a flexspline 230, a first circular spline 240S, a second circular spline 240D, and a bearing 250.

[0114] The strain wave gear reducer 210 is modified from the standard type A strain wave gear reducer 510A shown in FIG. 10 in the following respects.

[0115] (A) Extending the flexspline 230 upward. (B) Adding a mounting portion 245 to the first circular spline 240S. (C) Adding a second circular spline 240D.

[0116] By commercializing the strain wave gear reducer 210, the reducer 210 can be easily procured, and the horizontal articulated robot 100 equipped with the drive unit 150A of embodiment 1 can be manufactured in a short delivery time.

[0117] Eighth Embodiment In the second embodiment, a strain wave gear reducer 310 is used as the reducer of the first shaft motor 160. As shown in Fig. 16 , the strain wave gear reducer 310 includes a wave generator 320, a flexspline 330, a first circular spline 340S, a second circular spline 340D, and a bearing 350.

[0118] The strain wave gear reducer 310 has been modified in the following respects from the standard type B strain wave gear reducer 510B shown in FIG. 10B.

[0119] (1) The flexspline 330 is extended upward. (2) A mounting portion 345 is added to the first circular spline 340S. (3) A second circular spline 340D is added.

[0120] By commercializing the strain wave gear reducer 310, the reducer 310 can be easily procured, and the horizontal articulated robot 100 equipped with the drive unit 150B of embodiment 1 can be manufactured in a short delivery time.

[0121] Ninth Embodiment In the third embodiment, a strain wave gear reducer 410 is used as the reducer of the first shaft motor 160. As shown in Fig. 17 , the strain wave gear reducer 410 includes a wave generator 420, a flexspline 430, a first circular spline 440S, a second circular spline 440D, a third circular spline 440E, and bearings (cross rollers, as an example) 450.

[0122] The strain wave gear reducer 410 is modified from the standard type C strain wave gear reducer 510C shown in FIG. 10C in the following respects.

[0123] (A) Extending the flexspline 430 downward. (B) Adding a mounting portion 445 and a protrusion 447 to the first circular spline 440S. (C) Adding a third circular spline 440E. (D) Adding a cross roller 450.

[0124] By commercializing the strain wave gear reducer 410, the reducer 410 can be easily procured, and the horizontal articulated robot 100 equipped with the drive unit 150C of embodiment 3 can be manufactured in a short delivery time.

[0125] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0126] (1) In the first to sixth embodiments, the driving units 150A to 150F are applied to the first joint J1. The driving units 150A to 150F may also be applied to the second joint J2. Furthermore, the present invention is not limited to horizontal articulated robots and can be widely applied to any robot joint.

[0127] (2) In the first to sixth embodiments, the number of teeth on the internal teeth 41 of the first circular splines 240S, 340S, 440S, and 540S is two more than the number of teeth on the external teeth 31 of the flexsplines 230, 330, 430, and 530. However, the number of teeth on the internal teeth 41 of the first circular splines 240S, 340S, 440S, and 540S may be greater than the number of teeth on the external teeth 31 of the flexsplines 230, 330, 430, and 530, and the difference in the number of teeth is not limited to two. For example, the number of teeth on the internal teeth 41 of the first circular splines 240S, 340S, 440S, and 540S may be four more than the number of teeth on the external teeth 31 of the flexsplines 230, 330, 430, and 530.

[0128] REFERENCE SIGNS LIST 100 Horizontal articulated robot 110 Base (corresponding to the "support member" of the present invention) 115 Motor control board 120 First arm (corresponding to the "robot arm" of the present invention) 130 Second arm 145 Working axis 150A to 150F Driving device 160 First axis motor 170 Second axis motor 210, 310, 410, 510 Harmonic gear reducer 220, 320, 420, 520 Wave generator 230, 330, 430, 530 Flexspline 240S, 340S, 440S, 540S First circular spline 240D, 340D, 440D Second circular spline 440E Third circular spline 260, 560, 660 Motor holder 661 First motor holder 665 Second motor holder 710 Eccentric oscillating type differential reducer

Claims

1. A drive device for a robot arm rotatably supported on a support member, comprising: a motor; a motor holder; and a reducer that reduces the speed of the motor to rotate the robot arm, the reducer being a strain wave gear type including a wave generator coupled to the motor, a flexspline, a first circular spline, a second circular spline, and a bearing, the number of teeth of the first circular spline being greater than the number of teeth of the flexspline, the number of teeth of the second circular spline being the same as the number of teeth of the flexspline, the first circular spline and the second circular spline being located on the outer periphery of the flexspline and arranged in the axial direction of the wave generator in the order of the first circular spline and the second circular spline when viewed from the support member side, the bearing having a fixed ring and a movable ring and being arranged between the first circular spline and the support member, the fixed ring and the flexspline of the bearing being fixed to the support member, A drive device for a robot arm, comprising: the first circular spline fixed to the movable ring of the bearing; the robot arm fixed to the first circular spline; the motor holder fixed to the second circular spline; the motor holder located within an axial hole of the robot arm and supported by the robot arm via a bearing; and the motor fixed to the motor holder and located outside the support member.

2. A drive device for a robot arm rotatably supported on a support member, comprising: a motor; a motor holder; and a reducer that reduces the speed of the motor to rotate the robot arm, the reducer being a strain wave gear type including a wave generator, a flexspline, a first circular spline, a second circular spline, a third circular spline, and a bearing, the number of teeth of the first circular spline is greater than the number of teeth of the flexspline, the number of teeth of the second circular spline and the number of teeth of the third circular spline are the same as the number of teeth of the flexspline, the first circular spline, the second circular spline, and the third circular spline are located on the outer periphery of the flexspline and are arranged in the axial direction of the wave generator as viewed from the support member side in the order of the third circular spline, the first circular spline, and the second circular spline, the third circular spline being fixed to the support member, a drive device for a robot arm, wherein the third circular spline supports the first circular spline via the bearing; the robot arm is fixed to the first circular spline; the motor holder is fixed to the second circular spline; the motor holder is located within a shaft hole of the robot arm and is supported by the robot arm via a bearing; and the motor is fixed to the motor holder and is located outside the support member.

3. A drive device for a robot arm rotatably supported on a support member, comprising: a motor; a motor holder; a reducer that reduces the speed of the motor to rotate the robot arm; and a fixed member, wherein the reducer is a strain wave gear type including a wave generator, a flexspline, a first circular spline, and a bearing, wherein the number of teeth of the first circular spline is greater than the number of teeth of the flexspline, the bearing has a fixed ring and a movable ring and is arranged between the first circular spline and the support member, the fixed ring of the bearing and the flexspline are fixed to the support member, the first circular spline is fixed to the movable ring of the bearing, and the robot arm is fixed to the first circular spline, the motor holder is located within an axial hole of the robot arm and is supported by the robot arm via a bearing, and the fixed member fixes the motor holder to the support member, A drive device for a robot arm, wherein the motor is fixed to the motor holder and positioned outside the support member.

4. A drive device for a robot arm rotatably supported on a support member, comprising: a motor; a first motor holder; a second motor holder; a reducer that reduces the speed of the motor to rotate the robot arm; and a fixed member, wherein the reducer is a strain wave gear type including a wave generator, a flexspline, a first circular spline, and a bearing, wherein the number of teeth of the first circular spline is greater than the number of teeth of the flexspline, the bearing has a fixed ring and a movable ring and is disposed between the first circular spline and the support member, wherein the fixed ring of the bearing and the flexspline are fixed to the support member, the first circular spline is fixed to the movable ring of the bearing, the robot arm and the second motor holder are fixed to the first circular spline, the second motor holder supports the first motor holder via a bearing, and the fixed member fixes the first motor holder to the support member, A drive device for a robot arm, wherein the motor is fixed to the first motor holder and is located outside the support member.

5. A drive device for a robot arm rotatably supported on a support member, comprising: a motor; a motor holder; a reducer that reduces the speed of the motor to rotate the robot arm; and a fixed member, wherein the reducer is an eccentric oscillating type differential reducer that includes: a cylindrical gear case and an internal gear formed integrally with the inner circumference of the gear case; two planetary gears located inside the gear case and meshing with the internal gear; a crankshaft that passes through the gear case and the two planetary gears and connects to the motor; a carrier that is coaxially supported on the gear case via bearings; and a carrier pin that is attached to the carrier and passes through the two planetary gears, wherein the carrier is fixed to the support member and the robot arm is fixed to the gear case, and the fixed member fixes the motor holder to the support member, and the motor is fixed to the motor holder and is located outside the support member.

6. A horizontal articulated robot equipped with a robot arm drive device according to any one of claims 1 to 5.

7. A motor reducer used in a joint of a robot arm, the motor reducer being of a wave gear type including a wave generator coupled to the motor, a flexspline, a first circular spline, a second circular spline, and a bearing, the number of teeth of the first circular spline being greater than the number of teeth of the flexspline, the number of teeth of the second circular spline being the same as the number of teeth of the flexspline, the first circular spline and the second circular spline being on the outer peripheral surface of the flexspline and aligned in the axial direction of the wave generator, the first circular spline protruding radially outward beyond the second circular spline and having an attachment portion for attachment to the robot arm.

8. A motor reducer used in a joint of a robot arm, the reducer being a wave gear type including a wave generator coupled to the motor, a flexspline, a first circular spline, a second circular spline, a third circular spline, and a bearing, wherein the number of teeth of the first circular spline is greater than the number of teeth of the flexspline, the number of teeth of the second circular spline and the number of teeth of the third circular spline are the same as the number of teeth of the flexspline, the first circular spline, the second circular spline, and the third circular spline are on the outer peripheral surface of the flexspline and are arranged in the axial direction of the wave generator in the order of the third circular spline, the first circular spline, and the second circular spline, the third circular spline supports the first circular spline via the bearing, and the first circular spline protrudes radially outward more than the second circular spline and has an attachment portion for attachment to the robot arm.

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