Wrist joint unit

Abstract

To provide a compact and lightweight wrist joint unit by reducing the number of parts.SOLUTION: The wrist joint unit HU includes an arm 5, a first rotating member 6 supported by the arm 5 and rotatably provided around a first rotation axis C1, a second rotating member 7 supported by the arm 5 and rotatably provided around a second rotation axis C2 orthogonal to the first rotation axis C1, a first motor 9 supported by the arm 5 and rotationally driving the first rotating member 6, and a second motor supported by the arm 5 and rotationally driving the second rotating member 6. Further, the brake device includes a first transmission mechanism 8A that transmits the rotation of the first motor 9 to the first rotating member 6, a second transmission mechanism 8B that transmits the rotation of the second motor 9 to the second rotating member 7, and a brake plate 53 that is capable of abutting against the braked portions Bp, Bp of the first transmission mechanism 8A and the second transmission mechanism 8B.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wrist joint unit, and relates to a technique that is applied to, for example, a scalar robot, a cartesian robot, a vertical articulated robot, etc. [Background technology]

[0002] A wrist joint unit is rotatably connected to the tip of the robot arm. This wrist joint unit has two mutually perpendicular rotation axes, and is equipped with a first member that rotates around one axis and a second member connected to the first member so as to rotate around the other axis. An end effector is installed on the second member so that it can perform a predetermined task.

[0003] Furthermore, each actuator is provided with a brake mechanism to prevent the wrist joint unit from moving undesirably when power is not supplied to the robot from the power source. Since the wrist joint unit is provided at the tip of the robot's arm, it is preferable that it be lightweight, and since the end effector installed on the wrist joint unit performs the specified tasks, it is preferable that it be small to avoid interference with the surrounding area.

[0004] Patent Document 1 discloses a brake device for actuators involved in wrist operation of industrial robots. Patent Document 1 describes a system in which multiple actuators are braked simultaneously by a single brake device, which is said to reduce the overall weight and make the system more compact than when brakes are provided for each individual actuator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 2799416 Summary of the Invention [Problem to be solved by the invention]

[0006] The braking device described in Patent Document 1 requires dedicated brake plates for each actuator, similar to conventional brake-equipped actuators, which makes it more expensive and larger in size than actuators without brakes. Furthermore, since each brake plate in each actuator is braked by a single brake plate, the actuators must be located close to each other, which places restrictions on the layout of the actuators.

[0007] An object of the present invention is to provide a compact and lightweight wrist joint unit with a reduced number of parts. [Means for solving the problem]

[0008] The wrist joint unit of the present invention comprises: Arm and a first rotation member supported by the arm and rotatable about a first rotation axis; a second rotating member supported by the first rotating member and rotatable about a second rotation axis perpendicular to the first rotation axis; a first motor supported by the arm and configured to rotate the first rotary member; a second motor supported by the arm and configured to rotationally drive the second rotating member, a first transmission mechanism that transmits rotation of the first motor to the first rotating member; a second transmission mechanism that transmits rotation of the second motor to the second rotating member; A part of the first transmission mechanism and a part of the second transmission mechanism are braked parts, and a brake plate capable of coming into contact with these braked parts is provided.

[0009] With this configuration, rotation of the first motor rotates the first rotating member around the first rotation axis via the first transmission mechanism. Simultaneously, rotation of the second motor rotates the second rotating member around the second rotation axis, orthogonal to the first rotation axis, via the second transmission mechanism. A portion of the first transmission mechanism and a portion of the second transmission mechanism are designated as braked parts, and a brake plate is attached to these braked parts to restrict the rotation of the first and second transmission mechanisms. This prevents undesired movement of the first and second rotating members of the wrist joint unit. By using portions of the existing first and second transmission mechanisms as braked parts without providing a dedicated brake plate, the number of parts can be reduced compared to conventional structures, resulting in a more compact and lightweight wrist joint unit. Furthermore, because portions of the existing first and second transmission mechanisms are used as braked parts, the first and second motors do not need to be located close to each other, eliminating layout restrictions for the first and second motors. Therefore, it is possible to increase the degree of freedom in designing the wrist joint unit compared to conventional structures.

[0010] the first transmission mechanism is a first reduction mechanism that reduces the speed of rotation of the first motor, and the second transmission mechanism is a second reduction mechanism that reduces the speed of rotation of the second motor, the first reduction mechanism includes a first gear fixed to a motor shaft of the first motor, and a second gear fixed to the first rotating member, meshing with the first gear, and rotatable around a first rotation axis; the second reduction mechanism includes a third gear fixed to a motor shaft of the second motor, and a fourth gear rotatably supported by the arm, meshing with the third gear, and rotatable about a first rotation axis; The second and fourth gears may be used as the braked parts.

[0011] In this case, by using the second and fourth gears of the first and second reduction mechanism parts as braked parts as well, the increase in the number of parts can be suppressed compared to conventional structures, and the increase in weight of the wrist joint unit can be reduced.

[0012] The braked portion may be an outer peripheral portion or an end face of the second or fourth gear, so that a portion of the second or fourth gear can be easily used as the braked portion.

[0013] The brake plate may be made of a resin material or an elastic material, which can provide a stronger adhesion to the first and second transmission mechanisms and a larger braking force than a metal brake plate.

[0014] The brake plate may be provided with a step depending on the dimensions of the braked parts of the first and second transmission mechanisms. For example, if the outer diameters of the braked parts are different, providing a step in the brake plate allows the brake plate to come into contact with two braked parts at the same time. This makes it possible to prevent an increase in the number of parts. [Effects of the Invention]

[0015] The wrist joint unit of the present invention includes an arm, a first rotating member supported by the arm and rotatable about a first rotation axis, a second rotating member supported by the first rotating member and rotatable about a second rotation axis perpendicular to the first rotation axis, a first motor supported by the arm and rotatably driving the first rotating member, and a second motor supported by the arm and rotatably driving the second rotating member, the wrist joint unit further including a first transmission mechanism that transmits rotation of the first motor to the first rotating member, a second transmission mechanism that transmits rotation of the second motor to the second rotating member, and a brake plate that can abut against braked parts, with parts of the first transmission mechanism and the second transmission mechanism serving as braked parts. This reduces the number of parts, resulting in a compact and lightweight wrist joint unit. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a longitudinal sectional view of a wrist joint unit according to a first embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a diagram showing a schematic relationship between each motor and a spur gear of the wrist joint unit. [Figure 3] FIG. 10 is a longitudinal sectional view showing a braking state of the brake mechanism in the wrist joint unit. [Figure 4] FIG. 10 is a plan view of the wrist joint unit showing the braking state of the brake mechanism. [Figure 5] FIG. 10 is a longitudinal sectional view of a wrist joint unit according to a second embodiment of the present invention. [Figure 6A] FIG. 10 is an enlarged cross-sectional view of a main part of a wrist joint unit according to a third embodiment of the present invention, showing a non-braking state of a brake mechanism. [Figure 6B] FIG. 10 is an enlarged cross-sectional view of a main part of the wrist joint unit, showing a braking state of the brake mechanism. [Figure 7A] FIG. 10 is an enlarged cross-sectional view of a main part of a wrist joint unit according to a fourth embodiment of the present invention, showing a non-braking state of a brake mechanism. [Figure 7B] FIG. 10 is an enlarged cross-sectional view of a main part of the wrist joint unit, showing a braking state of the brake mechanism. [Figure 8A] FIG. 1 is a diagram showing a first example of a working device equipped with a wrist joint unit according to any of the embodiments. [Figure 8B] FIG. 10 is a diagram showing a second example of a working device equipped with a wrist joint unit according to any of the embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0017] [First embodiment] A wrist joint unit according to an embodiment of the present invention will be described with reference to Figures 1 to 4. A working device equipped with the wrist joint unit, which will be described later, is used in, for example, medical equipment or industrial equipment.

[0018] <Overall configuration of the wrist joint unit> As shown in Figure 1, the wrist joint unit HU includes an arm 5, a first rotating member 6, a reduction mechanism 8 including a second rotating member 7, first and second motors 9 and 10 (Figure 2) serving as drive sources, and a brake mechanism BM (described below). The first rotating member 6 is cantilevered by the arm 5 and rotatable about a first rotation axis C1. The second rotating member 7 is cantilevered by the first rotating member 6 and rotatable about a second rotation axis C2 perpendicular to the first rotation axis C1. An end effector 11 can be attached to the bevel gear 7, which is the second rotating member. The working device performs work by positioning the end effector 11 attached to the bevel gear 7 with respect to a workpiece.

[0019] <Arm> The base arm 5 has a base arm 5b and a tip arm 5a connected to the base arm 5b. The tip arm 5a is formed in a cylindrical shape with a bottom, and the base arm 5b is connected to the peripheral edge of the opening of the cylindrical portion of the tip arm 5a. A part of the speed reduction mechanism 8, which will be described later, is provided in a space S1 surrounded by the base arm 5b and the tip arm 5a.

[0020] <First rotating member, etc.> The first rotating member 6 is cantilevered by the distal arm 5a and rotatably mounted around the first rotation axis C1 via a bearing 1. The first rotating member 6 has a hollow cylindrical base rotating table 6a and a distal rotating table 6b fixed to the base rotating table 6a. In this example, the base rotating table 6a and the distal rotating table 6b are mounted on separate members and connected to each other, but the base rotating table 6a and the distal rotating table 6b may also be integrally mounted. The term "integrally mounted" means that the base rotating table 6a and the distal rotating table 6b are not formed by combining multiple elements but are molded as part or the whole of a single object from a single material, for example, by machining. The first and second rotation axes C1 and C2 refer to intangible rotation axes.

[0021] The outer peripheral surface of the outer ring of bearing 1 is fitted and fixed to the bottom of tip-side arm 5a, which is cylindrical with a bottom, and the outer peripheral surface of base-side rotating table 6a is fitted and fixed to the inner peripheral surface of the inner ring of bearing 1. Tip-side rotating table 6b, which is shaped like a square tube, is connected to one side of base-side rotating table 6a and is provided so as to protrude in one direction of the first rotation axis, i.e., upward in Figure 1. A space S2 is formed in tip-side rotating table 6b to prevent interference with bevel gears 7, 12, and a hole 6ba is formed in which a gear shaft 13 that rotatably supports bevel gear 7 is fitted and fixed. A cover 14 is provided on one side of tip-side rotating table 6b to prevent foreign matter from entering space S2 and to prevent grease from leaking.

[0022] <Drive source> As shown in Figures 1 and 2, the first and second motors 9 and 10 are each supported on the base-end arm 5b of the arm 5. The first motor 9 is a drive source that rotates the first rotating member 6, and the second motor 10 is a drive source that rotates the bevel gear 7, which is the second rotating member. A hole 5ba that supports the motor body of the first motor 9 is formed in the base-end arm 5b, and the motor shaft 9a of the first motor 9 is housed in the space S1 within the arm 5. The rotational axis of the motor shaft 9a is arranged parallel to the first rotational axis C1. A hole that supports the motor body of the second motor 10 is also formed in the base-end arm 5b, and the motor shaft 10a of the second motor 10 is also housed in the space S1 within the arm 5. The rotational axis of the motor shaft 10a of the second motor 10 is also arranged parallel to the first rotational axis C1.

[0023] <Deceleration mechanism> As shown in FIG. 1, the speed reduction mechanism 8 includes first and second transmission mechanisms. The first transmission mechanism transmits the rotation of a first motor 9 to a first rotating member 6. The second transmission mechanism transmits the rotation of a second motor 10 (FIG. 2) to a bevel gear 7, which is a second rotating member. Specifically, the first transmission mechanism is a first speed reduction mechanism 8A that reduces the rotation of the first motor 9, and the second transmission mechanism is a second speed reduction mechanism 8B that reduces the rotation of the second motor 10 (FIG. 2).

[0024] <First reduction mechanism section> The first reduction gear mechanism 8A has a spur gear 15 as a first gear, a spur gear 16 as a second gear, and a bearing 1. The spur gear 15 is fixed to the motor shaft 9a of the first motor 9. The spur gear 16 is fixed to the other side of the base-end rotating table 6a of the first rotating member 6 and meshes with the spur gear 15. The bearing 1 supports the first rotating member 6 for rotation with respect to the arm 5. The spur gear 16 is rotatable around the first rotation axis C1, and the spur gears 15 and 16 are housed in the space S1 within the arm 5. A deep groove ball bearing capable of bearing radial and axial loads is used as the bearing 1. By driving the first motor 9 to rotate, the first rotating member 6 is driven to rotate around the first rotation axis C1 at a predetermined reduction ratio by the first reduction gear mechanism 8A.

[0025] <Second reduction mechanism section> 1 and 2, the second reduction gear mechanism 8B has a spur gear 17 as a third gear, a spur gear 18 as a fourth gear, bearings 2 and 4, a base-side gear shaft 19, bevel gears 12 and 7, bearing 3, and a tip-side gear shaft 13. The spur gear 17 is fixed to the motor shaft 10a of the second motor 10 and meshes with the spur gear 18. The base-side gear shaft 19 is rotatably supported by the base-side arm 5b and the base-side rotating table 6a via bearings 4 and 2. The bearings 2 and 4 are provided coaxially with bearing 1, i.e., coaxially with the first rotating shaft C1.

[0026] A spur gear 18 is fixed to the axial base end of the gear shaft 19, and a bevel gear 12 is fixed to the axial tip end of the gear shaft 19. As described above, the gear shaft 19 is rotatably supported by the base end arm 5b etc. via bearings 4 and 2, and the spur gear 18 is fixed to the gear shaft 19. The spur gears 18 and 17 mesh with each other. Therefore, the spur gear 18 serving as a fourth gear is rotatably supported by the arm 5 and meshes with the spur gear 17 serving as a third gear, and is rotatable around the first rotation axis C1. The spur gear 18 is housed in a space S1 within the arm 5, and the bevel gear 12 is housed in a space S2 of the tip end turntable 6b and meshes with the bevel gear 7 serving as the second rotating member.

[0027] The gear shaft 13 on the tip side extends in the direction of the second rotation axis C2. The gear shaft 13 on the tip side has a small diameter portion 13a located at the tip end in the longitudinal direction and a large diameter portion 13b that is coaxially connected to the small diameter portion 13a. Most of the large diameter portion 13b is fitted and fixed into a hole 6ba in the tip side turntable 6b, and the small diameter portion 13a is arranged to protrude from the hole 6ba. A bevel gear 7 is fixed to the small diameter portion 13a of the gear shaft 13 via multiple (two in this example) bearings 3,3.

[0028] The inner ring of each bearing 3 is fitted and fixed to the small diameter portion 13a of the gear shaft 13, and the inner diameter of the boss of the bevel gear 7 is fitted and fixed to the outer ring of each bearing 3. As with bearing 1, deep groove ball bearings capable of supporting radial and axial loads are also used for bearings 2, 3, and 4 in FIG. 1. By driving and rotating second motor 10 in FIG. 2, bevel gear 7 shown in FIG. 1 is driven and rotated around second rotation axis C2 at a predetermined reduction ratio by second reduction mechanism 8B.

[0029] However, the base-end rotating table 6a is rotatably supported by the tip-end arm 5a via bearing 1. The base-end gear shaft 19 is fixed to this base-end rotating table 6a via bearing 2, and since bearings 1 and 2 are arranged coaxially, when the first motor 9 is driven to rotate, the base-end gear shaft 19 rotates as well. As a result, the bevel gear 7 rotates around the second rotation axis C2. At this time, in order for the bevel gear 7 not to rotate around the second rotation axis C2 but to rotate only around the first rotation axis C1, it is necessary to perform appropriate rotational driving on the gear shaft 19 on the base end side in response to the rotational driving of the first rotating member 6.

[0030] By rotating the first motor 9 and the second motor 10 (FIG. 2) in an appropriate relationship, it is possible to rotate the bevel gear 7 only about the first rotation axis C1. By rotating the second motor 10 (FIG. 2) appropriately without rotating the first motor 9, it is possible to rotate the bevel gear 7 only about the second rotation axis C2. Furthermore, by rotating the first motor 9 and the second motor 10 (Figure 2) in an appropriate relationship, it is possible to simultaneously rotate the bevel gear 7 around the first and second rotation axes C1 and C2 at the desired speeds.

[0031] The boss side and end faces of the bevel gear 7 are provided with threaded holes for mounting the end effector 11. The boss end faces of the bevel gear 7 are provided with mounting holes into which pins 21 can be installed, which ensure repeatability in mounting the end effector 11 and prevent misalignment in the rotational direction. The mounting holes extend parallel to the second rotation axis direction. For example, knock pins are used as the pins 21. In this case, by installing the pins 21 in the mounting holes in the boss end faces of the bevel gear 7, repeatability in mounting the end effector 11 and prevention of misalignment in the rotational direction can be ensured, and the end effector 11 can be easily attached to and detached from the bevel gear 7.

[0032] <Brake mechanism> The brake mechanism BM disables the rotation of the gear shafts 19 and 13 when power is not supplied from the power source to the wrist joint unit HU. As shown in FIGS. 1 and 2, the brake mechanism BM includes an electromagnet 50, a shaft 51, a compression coil spring 52, a brake plate 53, and braked parts Bp and Bp. As shown in FIGS. 2 and 3, a recess 5aa is formed at one longitudinal end of the distal arm 5a, and this recess 5aa communicates with the space S1 and is recessed in an orthogonal direction C3 perpendicular to the first rotation axis C1. An electromagnet 50 is fitted into and fixed to this recess 5aa. A shaft 51 is supported by the electromagnet 50 so as to be slidable in the orthogonal direction C3. The orthogonal direction C3 is the radial direction of the spur gears 16 and 18.

[0033] The brake plate 53 is fixed to the axial tip of the shaft 51. The shaft 51 restricts the movement of the brake plate 53 in one direction, i.e., the orthogonal direction C3. The brake plate 53 can come into contact with braked parts Bp, Bp, which are a part of the first reduction mechanism 8A and a part of the second reduction mechanism 8B. In this example, the spur gears 16, 18 of the first and second reduction mechanism 8A, 8B also serve as braked parts Bp, Bp.

[0034] The brake plate 53 is made of, for example, a resin material or an elastic material. The brake plate 53 includes an arc-shaped brake plate body 53a that faces the outer peripheries of the spur gears 16 and 18 and can abut against the outer peripheries of the spur gears 16 and 18, and a support body 53b connected to the back side of the brake plate body 53a. A spring accommodating hole that can accommodate a compression coil spring 52 is provided on the surface of the support body 53b that faces the electromagnet 50. The axial end of the shaft 51 is fixed to the bottom surface of the spring accommodating hole in the support body 53b. The compression coil spring 52 is inserted through the end of the shaft 51 and is interposed between the bottom surface of the spring accommodating hole and the surface of the electromagnet 50. When power is not supplied to the wrist joint unit HU from a power source, the compression coil spring 52 constantly applies a pressing force that presses the brake plate 53 against the two spur gears 16 and 18 by its spring force, as shown in FIGS. 3 and 4 .

[0035] The brake plate body 53a and the support body 53b are integrally formed. The term "integrally formed" means that the brake plate body 53a and the support body 53b are not formed by combining multiple elements but are formed as part or the whole of a single object from a single material by, for example, injection molding, machining, or the like. The brake plate body 53a and the support body 53b may be formed separately and fixed to each other. Of the brake plate 53, for example, only the brake plate body 53a may be made of a resin material or an elastic material, and the support body 53b may be made of, for example, metal. The brake plate body 53a, the support body 53b, and the shaft 51 may also be formed integrally.

[0036] As shown in Figure 2, when power is supplied from the power source to release the brake, the brake plate 53 is attracted by the electromagnet 50 against the spring force of the compression coil spring 52, and is separated from the spur gears 16 and 18. This allows the gear shafts 19 and 13 in Figure 1 to rotate.

[0037] <Action and effect> In the wrist joint unit HU described above, the first rotating member 6 is cantilevered on the arm 5, and the bevel gear 7, which is the second rotating member, is cantilevered on the first rotating member 6. This allows the first and second rotating members 6, 7 to have greater freedom of rotational movement without interfering with the first and second motors 9, 10 (FIG. 2) and support members. Furthermore, because the first and second rotating members 6, 7 are cantilevered, the size and weight can be reduced compared to a structure in which the first and second rotating members 6, 7 are supported at both ends. The first and second motors 9, 10 (FIG. 2) are not rotating members that rotate, but are supported on the base arm 5, so the motor bodies do not move. This allows for lightweight and compact first and second rotating members 6, 7. Furthermore, because the end effector 11 is attached to the bevel gear 7, which is the second rotating member, the number of parts is reduced, resulting in a compact and lightweight wrist joint unit HU.

[0038] The wrist joint unit HU further includes a bevel gear 12 that meshes with the bevel gear 7, and a gear shaft 19 to which the bevel gear 12 is fixed and which is rotatably supported by the arm 5 and the first rotating member 6 via bearings 4 and 2. The first rotating member 6 is rotatably supported by the arm 5 via bearing 1, and this bearing 1 and bearing 4, which rotatably supports the gear shaft 19 by the arm 5, are provided coaxially. Therefore, by rotating the first and second motors 9 and 10 (FIG. 2) in an appropriate relationship, the bevel gear 7, which is the second rotating member, can be rotated only about the first rotation axis C1. By rotating only the second motor 10 (FIG. 2) without rotating the first motor 9, the bevel gear 7, which is the second rotating member, can be rotated only about the second rotation axis C2.

[0039] Rotation of the first motor 9 rotates the first rotating member 6 about the first rotation axis C1 via the first reduction gear mechanism 8A. At the same time, rotation of the second motor 10 (FIG. 2) rotates the second rotating member 7 about the second rotation axis C2, which is perpendicular to the first rotation axis C1, via the second reduction gear mechanism 8B. A part of the first reduction gear mechanism 8A and a part of the second reduction gear mechanism 8B, in this example, the outer peripheries of the spur gears 16 and 18, are braked parts Bp, Bp, and the rotation of the first and second reduction gear mechanisms 8A and 8B is restricted by abutting the brake plate 53 against these braked parts Bp, Bp.

[0040] This prevents undesired movement of the gear shafts 19, 13 of the wrist joint unit HU. By using parts of the existing first and second reduction mechanisms 8A, 8B as the braked parts Bp, Bp without providing new dedicated brake plates, the number of parts can be reduced compared to conventional structures, resulting in a more compact and lightweight wrist joint unit HU. Furthermore, because parts of the existing first and second reduction mechanisms 8A, 8B are used as the braked parts Bp, Bp, there is no need to arrange the first and second motors 9, 10 close to each other, and there are no restrictions on the layout of the first and second motors 9, 10. This allows for greater freedom in designing the wrist joint unit HU compared to conventional structures. Since the brake plate 53 is made of a resin material or an elastic material, it can adhere more closely to the outer peripheries of the spur gears 16, 18 than a metal brake plate, thereby increasing the braking force.

[0041] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. It is possible to combine not only the parts specifically described in each embodiment, but also partially combine embodiments as long as there is no particular problem with the combination.

[0042] [Second embodiment: FIG. 5, with steps] 5, a step Ds may be provided in the brake plate 53 depending on the dimensions of the braked parts Bp, Bp of the first and second reduction mechanism units 8A, 8B. When the outer diameters of the two spur gears 16, 18 are different, for example, when the spur gear 16 of the first reduction mechanism unit 8A has a larger diameter than the spur gear 18 of the second reduction mechanism units 8A, 8B, a step Ds is provided in the brake plate body 53a of the brake plate 53. The portion of the brake plate body 53a that abuts against the spur gear 16 is connected to the portion that abuts against the spur gear 18 via the step Ds. The portion of the brake plate body 53a that abuts against the spur gear 16 is located radially outward of the portion that abuts against the spur gear 18.

[0043] In this way, when the outer diameters of the spur gears 16, 18 are different, the brake plate 53 can be brought into contact with the two braked portions Bp, Bp at the same time by providing the step Ds in the brake plate 53. This makes it possible to prevent an increase in the number of parts.

[0044] [Third embodiment: Figs. 6A and 6B, end face abutment type (1)] As shown in Figures 6A and 6B, the braked parts Bp, Bp may be the end faces of the second and fourth spur gears 16, 18. In this case, the brake plate 53 has a brake plate body 53a that faces the opposing end faces 16a, 18a of the spur gears 16, 18 and can abut against the end faces 16a, 18a of the spur gears 16, 18. The brake plate body 53a is formed, for example, with a wedge-shaped cross section that becomes thinner from the base end to the tip end. The axial tip end of the shaft 51 is fixed to the end face at the base end of the brake plate body 53a. At the same time, the compression coil spring 52 is inserted through the tip portion of the shaft 51 and is interposed between the end face of the brake plate body 53a and the surface of the electromagnet 50.

[0045] When no power is supplied from the power source to the wrist joint unit HU, as shown in Fig. 6B, the compression coil spring 52 constantly applies a pressing force by its spring to press the brake plate 53 against the end faces 16a, 18a of the two spur gears 16, 18. When power is supplied from the power source to release the brake, as shown in Fig. 6A, the electromagnet 50 attracts the brake plate 53 against the spring force of the compression coil spring 52 and separates it from the spur gears 16, 18. In this case, the same effects as those of the first embodiment are achieved.

[0046] [Fourth embodiment: Figs. 7A and 7B, end face abutment type (2)] As shown in FIGS. 7A and 7B , the brake mechanism BM may include, for example, a rotary actuator Ra, a shaft 51, a torsion coil spring 54, a brake plate 53 composed of a cam, and braked parts Bp, Bp. In this case, the brake plate 53 has a brake plate body 53a that faces the opposing end faces 16a, 18a of the spur gears 16, 18 and can abut against the end faces 16a, 18a of the spur gears 16, 18. The brake plate body 53a is composed of, for example, a cam, and both longitudinal ends 53aa, 53aa of this cam abut against the end faces 16a, 18a of the spur gears 16, 18. The axial tip of the shaft 51 is fixed to the end face at the base end of the brake plate body 53a. At the same time, the torsion coil spring 54 is inserted through the shaft 51 and fixed across the end face of the brake plate body 53a and the actuator body of the rotary actuator Ra.

[0047] When no power is supplied from the power source to the wrist joint unit HU, as shown in Fig. 7B, the torsion coil spring 54 constantly applies a spring force to press the brake plate 53 against the end faces 16a, 18a of the two spur gears 16, 18. When power is supplied from the power source to release the brake, as shown in Fig. 7A, the brake plate 53 is rotated by the rotary actuator Ra against the spring force of the torsion coil spring 54 and separated from the spur gears 16, 18. In this case as well, the same effects as those of the first embodiment are achieved.

[0048] At least one of the bearings 1, 2, 3, and 4 shown in Figures 1 and 5 may be replaced with a rolling bearing other than a deep groove ball bearing. However, a rolling bearing capable of bearing radial and axial loads is used. For example, an angular contact ball bearing can be used as such a rolling bearing. An end effector may be attached to the bevel gear, which is the second rotating member, via an intermediate member such as a tool changer.

[0049] <Work equipment> <Cartesian robot: Figure 8A> As shown in FIG. 8A, a Cartesian robot (working device) 25 equipped with a wrist joint unit HU may be used. Cartesian robot 25 in this example employs an XZ stage that moves in two orthogonal axial directions, the X axis and the Z axis. Cartesian robot 25 includes an X-axis electric actuator 26 and a Z-axis electric actuator 27 that respectively correspond to the X axis and the Z axis that are orthogonal to each other. Z-axis electric actuator 27 includes a pillar portion 29 that extends in the Z axis direction, which is the up-and-down direction in FIG. 8A, on a support base 28, a guide portion 30 fixed to one side of pillar portion 29, a Z-axis stage 31 that slides along guide portion 30, a Z-axis motor 32 that is the drive source of Z-axis stage 31, and a conversion mechanism such as a ball screw (not shown) that converts the rotation of Z-axis motor 32 into linear reciprocating motion along the Z axis.

[0050] The X-axis electric actuator 26 has a guide part 33 that is supported by the Z-axis stage 31 and extends along the X-axis direction, which is the left-right direction in Fig. 8A, an X-axis stage 34 that slides along the guide part 33, an X-axis motor 35 that is the drive source of the X-axis stage 34, and a conversion mechanism such as a ball screw (not shown) that converts the rotation of the X-axis motor 35 into linear reciprocating motion along the X-axis. A wrist joint unit HU is connected to the X-axis stage 34 via a bracket 36 or the like. A first rotation axis C1 of this wrist joint unit HU is arranged, for example, parallel to the Z-axis.

[0051] A Y-axis electric actuator 37 is provided on support base 28 in the Y-axis direction, which is perpendicular to the X-axis and Z-axis. Y-axis electric actuator 37 has a guide portion 38 extending along the Y-axis direction on support base 28, a Y-axis stage 39 that slides along guide portion 38, a Y-axis motor 40 that is the drive source for Y-axis stage 39, and a conversion mechanism such as a ball screw (not shown) that converts the rotation of Y-axis motor 40 into linear reciprocating motion along the Y-axis. A workpiece W is placed on Y-axis stage 40.

[0052] The Cartesian robot 25, the Y-axis electric actuator 37, and the motors of the wrist joint unit HU are controlled in cooperation with each other by a control device (not shown). This allows the Cartesian robot 25 to position the end effector 11 attached to the tip of the wrist joint unit HU with respect to the workpiece W and perform the desired task. This working device can be used in smaller spaces, near walls, or with multiple devices lined up at close intervals, compared to working devices using conventional wrist joint units.

[0053] <Scalar robot: Figure 8B> As shown in Fig. 8B, a SCARA robot (working device) 41 may be provided with a wrist joint unit HU. In this SCARA robot 41, a first arm 44 on the base end side is rotatably mounted around the Z-axis direction via a rotation mechanism 43 on a rotation drive source provided in a base unit 42. A second arm 46 is rotatably mounted around the Z-axis direction via a rotation mechanism 45 on the tip of the first arm 44. A wrist joint unit HU is connected to the tip of the second arm 45 via a linear guide mechanism 47 that can be moved and driven in the Z-axis direction. A first rotation axis C1 of this wrist joint unit HU is also arranged parallel to the Z-axis. A workpiece W is placed and supported on a support table 28.

[0054] The motors of the SCARA robot 41 and the wrist joint unit HU are controlled in cooperation with a control device (not shown). This allows the SCARA robot 41 to position the end effector 11 attached to the tip of the wrist joint unit HU with respect to the workpiece W to perform the desired task. This working device can also work in narrow spaces, near walls, or with multiple units lined up at close intervals, compared to working devices using conventional wrist joint units.

[0055] Although not shown, for example, a wrist joint unit may be provided at the tip of a four-axis or less vertical articulated robot. Of course, a five-axis or six-axis vertical articulated robot can also be provided with a wrist joint unit at the tip. In this case, the same effects as those described above can be achieved.

[0056] Although the embodiments of the present invention have been described above, the disclosed embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0057] 5...Arm, 6...First rotating member, 7...Bevel gear (second rotating member), 8A...First reduction mechanism (first transmission mechanism), 8B...Second reduction mechanism (second transmission mechanism), 9...First motor, 9a...Motor shaft, 10...Second motor, 10a...Motor shaft, 15...Spur gear (first gear), 16...Spur gear (second gear), 17...Spur gear (third gear), 18...Spur gear (fourth gear), 53...Brake plate, Bp...Braked part, Ds...Step, HU...Wrist joint unit

Claims

1. Arm and a first rotation member supported by the arm and rotatable about a first rotation axis; a second rotation member supported by the first rotation member and rotatable about a second rotation axis perpendicular to the first rotation axis; a first motor supported by the arm and configured to rotate the first rotary member; a second motor supported by the arm and configured to rotationally drive the second rotating member, a first transmission mechanism that transmits rotation of the first motor to the first rotating member; a second transmission mechanism that transmits rotation of the second motor to the second rotating member; The wrist joint unit includes a brake plate that can come into contact with a part of the first transmission mechanism and a part of the second transmission mechanism as braked parts.

2. 2. The wrist joint unit according to claim 1, wherein the first transmission mechanism is a first reduction mechanism that reduces the speed of rotation of the first motor, and the second transmission mechanism is a second reduction mechanism that reduces the speed of rotation of the second motor, the first reduction mechanism includes a first gear fixed to a motor shaft of the first motor, and a second gear fixed to the first rotating member, meshing with the first gear, and rotatable around a first rotation axis; the second reduction mechanism includes a third gear fixed to a motor shaft of the second motor, and a fourth gear rotatably supported by the arm, meshing with the third gear, and rotatable about a first rotation axis; A wrist joint unit using the second and fourth gears as the braked parts.

3. 3. A wrist joint unit according to claim 2, wherein the braked portion is an outer peripheral portion or an end face of the second and fourth gears.

4. 3. A wrist joint unit according to claim 1, wherein the brake plate is made of a resin material or an elastic material.

5. 3. The wrist joint unit according to claim 1, wherein the brake plate is provided with a step in accordance with the dimensions of the braked parts of the first and second transmission mechanisms.

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