JP5359640B2 - Robot wrist device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a lubricant in a sealed space of a decelerator from leaking outside on the decelerator provided at the tip of a wrist rotation part for transmitting rotation to an end effector attaching member. <P>SOLUTION: A wrist device of a robot is equipped with a first decelerator 7 for a flange (end effector attaching member) and a second decelerator 8 for the wrist rotation part 3 on a tip surface and a side face of a housing 5 of the wrist rotation part 3, and is equipped with a motor 6 for driving the flange via the first decelerator 7 in the housing 5. In this case, a communication path 65 is formed, for communicating between a first sealed space 32 in the first decelerator 7 and a second sealed space 57 in the second decelerator 8. A stopper 67 is provided, which usually closes the communication path 65 and opens the communication path 65 when an internal pressure in the first sealed space 32 is higher than an internal pressure in the second sealed space 57 by a predetermined value or higher. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a wrist device for a robot, and more particularly to a wrist device for a robot that prevents an abnormal increase in internal pressure of a casing of a reduction gear.

  A wrist device for a robot is configured by rotatably attaching a wrist rotating portion having a rotatable end effector mounting member to a distal end portion of an arm. The wrist rotation unit is provided with a speed reduction device that reduces the rotation of the motor and transmits it to the end effector mounting member. The inside of the casing of the speed reduction device is a sealed space. An appropriate amount of lubricant (such as grease) is contained for lubrication.

Although there is no direct relationship with the present invention, in Patent Document 1, in order to prevent intrusion of water or the like into the sealed space of the wrist rotating unit, the wrist to which the wrist rotating unit is attached has a sealed structure, The sealed space and the inside of the arm communicate with each other through a narrow air flow path so that air having a pressure higher than the pressure of the outside air is supplied to the inside of the arm. According to this, since the sealed space of the wrist rotating part is maintained at a pressure higher than the pressure of the outside air, water or the like can be prevented from entering the sealed space of the wrist rotating part from the seal portion, Since the sealed space of the wrist rotating part connected by a narrow air flow path is kept at the same or slightly lower pressure as the inner space of the arm, the lubricant in the sealed space of the wrist rotating part may be pushed out into the arm. It can be prevented.
JP 7-75992 A

  In Patent Document 1, a motor for driving an end effector mounting member is provided in an arm, and a motor provided in the arm and a speed reducer provided in a wrist rotating unit are connected by a belt transmission mechanism. ing.

  If the drive motor for the end effector mounting member is provided not on the arm but on the wrist rotating portion, the rotation transmission configuration is simplified. However, if a motor is arranged in the wrist rotating part, the air temperature in the casing of the reduction gear increases due to the heat generated by the motor, and the air pressure in the casing increases due to the temperature rise. If this increase in air pressure in the casing overlaps with an adverse condition that exceeds the assumed operating conditions, such as the service life of the sealing member has been exceeded, the lubricant in the sealed space will flow from the seal part to the outside. There is a risk of leakage.

  In the configuration disclosed in Patent Document 1, the pressure in the sealed space of a speed reducer (a speed reducer that decelerates the rotation of the motor and transmits it to the end effector mounting member) provided on the inner side of the tip of the wrist rotating portion is externally applied. In addition to being kept higher than the air pressure, when the pressure rises due to the air being warmed by the heat of the motor, the lubricant in the sealed space of the speed reducer leads the output shaft of the speed reduction mechanism to the outside. There is a risk of leakage from the sealing portion of the through hole. In particular, in a small robot, considering that the objects handled by the end effector vary widely and may handle food, the rotation is slowed down by the end effector mounting member provided at the tip of the wrist rotating part. It is the most important issue to prevent the leakage of lubricant from the speed reducer to be transmitted.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reduction gear that is provided at a tip portion of a wrist rotation portion and transmits rotation to an end effector mounting member. It is an object of the present invention to provide a wrist device for a robot that can prevent a lubricant from leaking outside.

  According to the present invention, a first reduction device for an end effector mounting member and a second reduction device for a wrist rotation unit are provided on different surfaces of the housing of the wrist rotation unit, and the end effector attachment member is interposed via the first reduction device. In the case where the motor to be driven is provided in the housing of the wrist rotating part, a communication path is formed which communicates between the first sealed space of the first reduction gear and the second sealed space of the second reduction gear, and is always connected to the communication path. And an open / close valve is provided that opens the communication passage when the pressure in the first sealed space is higher than the pressure in the second sealed space by a predetermined value or more.

  In the present invention having this configuration, when the temperature of the first reduction gear increases due to the heat generated by the motor and the air pressure in the first sealed space increases, the on-off valve opens to reduce the air in the first sealed space to the second speed. Relief into the second sealed space of the device. For this reason, it can prevent that the air pressure in 1st sealed space becomes high abnormally, and can prevent the leakage of the lubricant from the 1st reduction gear as much as possible.

Sectional drawing of the principal part which shows one Embodiment of this invention Enlarged view showing the operation of the main part Cross section of wrist device

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows a distal end portion of a robot main body formed by sequentially connecting a plurality of arms so that the arm 1 can move forward, backward, left and right in cooperation with other arms (not shown). It can move in all directions up and down.
The frame 2 that is the main body of the arm 1 is of a plurality of divided types, and a wrist rotating portion 3 is supported on the inner side of the distal end portion of the frame 2 so as to be rotatable about the axis W. Further, the distal end portion of the wrist rotating portion 3 The flange 4 is supported rotatably about the axis F. The flange 4 is an end effector mounting member to which an end effector such as a hand is attached.

  The support structure and rotational drive configuration of the wrist rotating part 3 and the flange 4 will be described. First, the wrist rotating part 3 is mainly composed of a housing 5 having a hollow inside, and the flange 4 is provided in the hollow inside of the housing 5. A motor 6 for rotationally driving the motor is disposed. The rotation center axis W of the wrist rotation unit 3 and the rotation center axis F of the flange 4 are orthogonal to each other, and different surfaces of the housing 5 of the wrist rotation unit 3, that is, the front end surface orthogonal to the rotation center axis F are rotated. A first speed reduction device 7 and a second speed reduction device 8 are disposed on side surfaces orthogonal to the central axis W, respectively.

  The first speed reduction device 7 and the second speed reduction device 8 are configured by housing (built in) the first speed reduction mechanism 11 and the second speed reduction mechanism 12 in the first casing 9 and the second casing 10. The device 8 is configured to be larger than the first reduction gear 7. The first speed reduction mechanism 11 and the second speed reduction mechanism 12 are both constituted by a wave gear speed reduction device, and have an elliptical first rigid cam 13 and second rigid cam 14 as an input portion, and a flexible first wave bearing 15. And second wave bearing 16, flexible cylindrical first flexible external gear 17 and second flexible external gear 18, first rigid internal gear 19 and second rigid internal gear 20 have.

  The first casing 9 of the first reduction gear device 7 is configured by connecting a first rigid internal gear 19 and two casing elements 21 and 22 in three stages and connecting them with bolts (connecting means) 23. The two casing elements 21 and 22 have a cylindrical shape, and the flange 4 is rotatably fitted and supported via a cross roller bearing 24 inside thereof. The flange 4 and the casing element 21 are sealed with an oil seal (seal member) 25.

  The first rigid internal gear 19 has a substantially cylindrical shape, and an annular mounting portion 19a coupled to the two casing elements 21 and 22 is formed on the outer peripheral portion on one end side. The first rigid internal gear 19 has a circular opening in which an internal gear portion 19b is formed on the inner peripheral surface. Therefore, the first casing 9 is configured such that one end surface is opened at the circular opening of the internal gear portion 19 b of the first rigid internal gear 19 and the other end surface is closed by the flange 4. An O-ring groove 26 is formed on the cylindrical outer peripheral surface of the internal gear portion 19 b of the first rigid internal gear 19, and an O-ring (seal member) 27 is fitted in the O-ring groove 26.

  With respect to the first casing 9, a cylindrical casing receiver (fitting portion) 28 is integrally formed on the front end surface of the housing 5 of the wrist rotating portion 3. The first casing 9 is disposed on the front end surface of the housing 5 so that the first rigid internal gear 19 is fitted inside the casing receiver 28, and is fixed to the casing receiver 28 by bolts (coupling means) 29. Has been. In this fixed state, the first casing 9 and the casing receiver 28 are sealed by the O-ring 27 attached to the first rigid internal gear 19.

  A rotating shaft 30 of the motor 6 provided in the housing 5 of the wrist rotating unit 3 protrudes from the front end surface portion of the housing 5 into the first casing 9. The central axis of the rotary shaft 30 coincides with the rotational center axis F of the flange 4. The rotation shaft 30 and the front end surface portion of the housing 5 are sealed with an oil seal (seal member) 31 attached to the front end surface portion of the housing 5. A space between the coupling surfaces of the two casing elements 21 and 22 and the first rigid internal gear 19 is sealed with a sealant (not shown) applied to the coupling surfaces. Therefore, the internal space of the first casing 9 is sealed to form a first sealed space 32.

  In the first speed reduction mechanism 11 housed in the first sealed space 32, the first rigid cam 13 is fitted to the rotating shaft 30 of the motor 6 and fixed by a screw 33. The flexible inner ring 15 a of the first wave bearing 15 is fitted to the first wave bearing 15. On the other hand, the first flexible external gear 17 is fixed to the flange 4 by the bolt 34 in a state where the external gear portion 17 a is positioned inside the internal gear portion 19 b of the first rigid internal gear 19. . When the first casing 9 is fitted to the casing receiver 28, the external gear portion 17 a of the first flexible external gear 17 is fitted to the flexible outer ring 15 b of the first wave bearing 15. The external gear portion 17a bends into an elliptical shape, so that the external teeth mesh with the internal teeth of the internal gear portion 19b of the first rigid internal gear 19 at two locations.

  In the first speed reduction mechanism 11, when the rotary shaft 30 rotates, as is well known, the rotation is caused by meshing between the external teeth of the first flexible external gear 17 and the internal teeth of the first rigid internal gear 19. It is decelerated and transmitted to the flange 4, and the flange 4 rotates. In order to lubricate the first speed reduction mechanism 11, an appropriate amount of lubricant, for example, lubricating oil, is stored in the first casing 9, that is, in the first sealed space 32.

  The second casing 10 of the second reduction gear 8 includes an inner casing 38 formed by connecting an annular auxiliary inner casing element 36 to a substantially circular dish-shaped inner casing element 35 by a bolt (coupling means) 37, and an outer casing 38. An outer casing 41 is formed by coupling the second rigid internal gear 20 to the casing element 39 with a bolt (coupling means) 40, and the outer casing 41 rotates outside the inner casing 38 via a cross roller bearing 42. The mating support is possible.

  In the second casing 10, the inner casing element 35 and the outer casing element 39 are sealed with an oil seal (seal member) 43. In addition, O-ring grooves 44 and 45 are formed on the joint surface of the outer casing element 39 with the second rigid internal gear 20 and the joint surface with the side surface of the housing 5 of the second rigid internal gear 20, respectively. The outer casing element 39 and the second rigid internal gear 20 are sealed by an O-ring (seal member) 46 fitted into one O-ring groove 44.

  A short cylindrical casing receiver (fitting portion) 47 for positioning the second casing 10 is integrally formed on the side surface of the housing 5 of the wrist rotating portion 3. Further, a shaft portion 48 is integrally provided on the side surface of the housing 5 so as to be located at the center of the casing receiver 47. The central axis of the shaft portion 48 coincides with the rotation center axis W of the wrist rotating portion 3. An input shaft 49 as an input portion of the second reduction mechanism 12 is supported on the shaft portion 48 via a ball bearing 50 so as to be rotatable.

  The second casing 10 is disposed on the side surface of the housing 5 so that the outer casing element 39 and the second rigid internal gear 20 are fitted in the casing receiver 47, and is fixed to the housing 5 by bolts 51. A space between the side surface of the housing 5 and the second rigid internal gear 20 is sealed by an O-ring 52 fitted in an O-ring groove 45 of the second rigid internal gear 20.

In a state where the second casing 10 is fixed to the housing 5, the tip end portion of the input shaft 49 protrudes outward from the inner casing element 35. The input shaft 49 and the inner casing element 35 are sealed with an oil seal (seal member) 53. Further, a lid body 54 having a bearing case portion 54 a is fixed to the inner casing element 35 with a screw 55. A screw hole (through hole) 56 into which the screw 55 is screwed is formed so as to penetrate the inner casing element 35, and the inside of the second casing 10 is open to the outside. When the screw 55 is screwed into the screw hole 56, the screw hole 56 is sealed with the screw 55.
By sealing the screw hole 56 with the screw 55 and sealing each part with the oil seals 43 and 53 and the O-rings 46 and 52, the internal space of the second casing 10 becomes a sealed second sealed space 57. It is preferable to apply a sealing agent to the screw 55.

  A ball bearing 58 is mounted on the bearing case portion 54 a of the lid 54, and the upper end portion of the input shaft 49 is rotatably supported by the ball bearing 58. A pulley 59 is rotatably supported on the ball bearing 58, and the pulley 59 is connected to the input shaft 49 by a bolt 60.

The inner casing element 35 of the second casing 10 is fixed to the frame 2 of the arm 1 by bolts 61. As a result, the wrist rotating unit 3 is cantilevered on the inner casing 38 so as to be rotatable about the axis W via the ball bearing 58, the input shaft 49, and the ball bearing 50.
Although not shown, a motor for driving the wrist rotating unit 3 is disposed in the arm 1, and this motor is connected by a pulley 59 and a belt 62. Therefore, when the driving motor of the wrist rotating unit 3 is activated, the rotation is transmitted to the pulley 59 by the belt 62, and the pulley 59 and the input shaft 49 rotate integrally.

  In the second casing 10, the second rigid cam 14 of the second reduction mechanism 8 is fixed to the input shaft 49 by a bolt 63, and the flexible inner ring 16 a of the second wave bearing 16 is attached to the second rigid cam 14. It is mated. On the other hand, the second flexible external gear 18 is fixed to the inner casing element 35 by the bolt 64 in a state where the external gear portion 18a is positioned inside the internal gear portion 20a of the second rigid internal gear 20. ing. When the second casing 10 is fitted to the casing receiver 47, the external gear portion 18a of the second flexible external gear 18 is fitted to the flexible outer ring 16b of the second wave bearing 16. The external gear portion 18a bends into an elliptical shape, whereby the external teeth mesh with the internal teeth of the internal gear portion 20a of the second rigid internal gear 20 at two locations.

  In the second reduction mechanism 12, when a motor (not shown) in the arm 1 is activated, the rotation is transmitted to the input shaft 49 via the belt 62, and the rotation of the input shaft 49 is second flexible as is well known. The second rigid internal gear 20 rotates by being decelerated by the meshing of the external teeth of the external external gear 18 and the internal teeth of the second rigid internal gear 20. Since the second rigid internal gear 20 is fixed to the housing 5, the wrist rotating unit 3 rotates about the axis W when the second rigid internal gear 20 rotates. In order to lubricate the second speed reduction mechanism 12, an appropriate amount of lubricant, for example, lubricating oil, is stored in the second casing 10, that is, in the second sealed space 57.

  As shown in FIG. 1, a communication path 65 for communicating the first sealed space 32 and the second sealed space 57 is formed in the housing 5 of the wrist rotating unit 3. One end of the communication path 65 opens at the front end surface of the housing 5 and directly communicates with the first sealed space 32, and the other end opens at the side surface of the housing 5 and is formed in the second rigid internal gear 20. The second sealed space 57 communicates with the connected connection path 66.

  The communication path 65 includes a first path 65a that communicates with the first sealed space 32 and a second path 65b that is bent at a right angle from the middle of the first path 65a and communicates with the connection path 66, and has a substantially L-shape as a whole. There is no. A plug 67 as an on-off valve is movably inserted in the middle of the first passage 65a. The plug 67 is urged to receive air pressure in the first sealed space 32 and to come into contact with a compression coil spring 68 as urging means disposed in the back of the first passage 65a. It is located closer to the first sealed space 32 than the intersection between the 65a and the second passage 65b. In order to prevent the plug 67 from coming off from the first passage 65a, a retaining ring (stopper) 69 is provided at an opening end portion of the first passage 65a into the first sealed space 32.

  As shown in FIG. 2 (a), when the plug 67 is located on the first sealed space 32 side of the first passage 65a with respect to the intersection with the second passage 65b, the plug 67 is connected to the first passage 65a. The passage between the two passages 65b is cut off, that is, the communication passage 65 is closed, and moves in the direction of the arrow A against the spring force of the compression coil spring 68. As shown in FIG. When passing through the intersection of 65a and the second passage 65b, the first passage 65a and the second passage 65b are opened, that is, the communication passage 65 is opened.

  Next, in the above configuration, the operation of the communication path 65 will be described together with the procedure for assembling the first reduction gear 7 and the second reduction gear 8 to the housing 5 of the wrist rotating unit 3. The first reduction gear 7 is assembled to the housing 5, and then the second reduction gear 8 is assembled. That is, while the flange 4 is rotatably supported inside the two casing elements 21 and 22 via the cross roller bearing 24, the casing elements 21 and 22 and the first rigid internal gear 19 are connected by the bolts 23. Fix and assemble the first casing 9. At this time, a sealing agent is applied to the coupling surface between the casing elements 21 and 22 and the first rigid internal gear 19 to seal the space between the coupling surfaces. Then, an oil seal 25 is inserted between the flange 4 and the casing element 21. Further, the first flexible external gear 17 is fixed to the flange 4 with bolts 34. Then, an O-ring 27 is fitted into the O-ring groove 26 of the first rigid internal gear 19. Further, the first casing 9 is directed upward (the first rigid internal gear 19 side is upward), and an appropriate amount of lubricating oil is injected into the first casing 9.

  On the other hand, the first wave bearing 15 is fitted on the outer periphery of the first rigid cam 13, and then the first rigid cam 13 is fixed to the rotary shaft 30 with a screw 33. Thereafter, the housing 5 is turned downward (the rotary shaft 30 protrudes downward), and the external gear portion 17a of the first flexible external gear 17 of the first casing 9 in the upward state is moved to the first wave bearing. The first rigid internal gear 19 is inserted into the casing receiver 28 while being fitted to the 15 flexible outer rings 15b.

  When the O-ring 27 is inserted into the casing receiver 28, the inside of the first casing 9 (first sealed space 32) is sealed, and the subsequent insertion of the first rigid internal gear 19 into the casing receiver 28 is performed. The internal volume of the first sealed space 32 is reduced. For this reason, the air pressure in the first sealed space 32 increases. At this time, as the internal pressure of the first sealed space 32 increases, the plug 67 in the communication passage 65 moves in the first passage 65a in the direction of arrow A, which is the back direction, and slightly compresses the compression coil spring 68. The communication path 65 is kept closed. Thus, the attachment of the first reduction gear 11 to the housing 5 is completed. It should be noted that the spring force of the compression coil spring 68 is set to such a magnitude that the communication path 65 can be maintained in a closed state in spite of an increase in air pressure in the first sealed space 32 during assembly. .

Next, the outer casing element 39 is rotatably supported by the cross roller bearing 42 while assembling the inner casing 38 by connecting the inner casing element 35 and the auxiliary inner casing element 36 of the second casing 10 with the bolts 37. Subsequently, the O-ring 46 is fitted into the O-ring groove 44 of the outer casing element 39, and then the second rigid internal gear 20 is fixed to the outer casing element 39 with the bolts 40 to assemble the outer casing 41.
Thus, the second casing 10 in which the outer casing 41 is rotatably disposed on the inner casing 38 is assembled. An oil seal 43 is inserted between the inner casing element 35 and the outer casing element 39 of the second casing 10. Further, the second flexible external gear 18 is fixed to the inner casing element 35 of the second casing 10 with a bolt 64.

  On the other hand, the second rigid cam 14 fitted with the second wave bearing 16 is fixed to the input shaft 49 by the bolt 63, and the input shaft 49 can be rotated to the shaft portion 48 of the housing 5 via the ball bearing 50. Attach to. Then, after the O-ring 52 is fitted in the O-ring groove 45 of the second rigid internal gear 20, the second flexible external gear 18 is fitted to the outer periphery of the second wave bearing 16. The second casing 10 is fitted into the casing receiver 47 and fixed to the housing 5 with bolts 61. Thereby, the outer casing 41 of the second casing 10 is fixed to the housing 5.

  Next, for example, an appropriate amount of lubricating oil is injected into the second casing 10 from the gap between the inner casing element 35 and the input shaft 49, and then an oil seal is provided between the inner casing element 35 and the input shaft 49. 53 is inserted. Then, the lid 54 to which the ball bearing 58 is mounted is disposed on the inner casing element 35 so that the ball bearing 58 is fitted to the input shaft 49. Next, the screw 55 coated with a sealant is screwed into the screw hole 56 to fix the lid 54 to the inner casing element 35. Thereby, the 2nd casing 10 (2nd sealed space 57) is made into a sealed state. Subsequently, the pulley 59 is fixed to the input shaft 49 with the bolt 60.

  As described above, the first reduction gear device 11 and the second reduction gear device 12 are attached to the front end surface and the side surface of the wrist rotating unit 3, respectively. The wrist rotating unit 3 is disposed inside the frame 2 divided into a plurality of arms 1, and the outer casing 41 of the second casing 10 is fixed to the frame 2 with bolts 61. As a result, the wrist rotating unit 3 is supported in the frame 2 so as to be rotatable about the axis W. Thereafter, the belt 62 is stretched between the pulley 59 and a pulley of a motor (not shown). The wrist rotating part 3 can be disposed in the frame 2 by dividing the frame 2 into a plurality of parts.

  When the robot is actually used, the arm 1 is moved in all directions, up, down, front, back, left, and right, the wrist rotating unit 3 is rotated around the axis W by a motor (not shown) in the arm 1, and the flange 4 is formed in the housing 5. The motor 6 is rotated about the axis F by the rotating shaft 30 of the motor 6. The motor 6 generates heat as it is energized and rotationally drives the flange 4, and the air temperature in the first sealed space 32 and the second sealed space 57 rises due to the heat.

  Since the second sealed space 57 is sealed by screwing the screw 55 into the screw hole 56 in a state where it is in communication with the atmosphere, the motor is initially at atmospheric pressure and has a larger internal volume than the first sealed space 32. The temperature rise due to the heat of 6 is small and therefore the pressure rise is small. On the other hand, the first sealed space 32 is atmospheric pressure from the beginning by compressing the internal air when the first casing 9 (first rigid internal gear 19) is fitted into the casing receiver 28. In addition to the higher air pressure, the pressure further increases due to an increase in air temperature due to heat generated by the motor 6.

  When the internal pressure of the first sealed space 32 becomes higher than the internal pressure of the second sealed space 57 by the heat generated by the motor 6, the plug 67 in the communication path 65 receives the pressure of the first sealed space 32 and compresses it. It moves in the direction of arrow A against the spring force of the coil spring 68 and opens the communication path 65 as shown in FIG. Thereby, the air in the 1st sealed space 32 flows in the 2nd sealed space 57 through the communicating path 65 and the connection path 66, As a result, the internal pressure of the 1st sealed space 32 falls. Since the pressing force in the direction of arrow A acting on the plug body 67 decreases due to the decrease in the internal pressure of the first sealed space 32, the plug body 67 moves in the direction opposite to the arrow A by the spring force of the compression coil spring 68. Then, the communication path 65 is closed again.

  Since the air outflow speed from the first sealed space 32 to the second sealed space 57 at this time is fast, the open time of the communication path 65 is short. For this reason, the communication path 65 is opened and closed in a state where the first speed reduction device 11 is above the second speed reduction device 12 or in a state where the second speed reduction device 12 is above the first speed reduction device 11. Even in this case, the lubricant in the first sealed space 32 flows into the second sealed space 57 through the communication path 65, or the lubricant in the second sealed space 57 passes through the communication path 65. There is almost no flow inside.

When the air temperature in the first sealed space 32 rises to some extent with the opening of the communication passage 65 as described above, the substantially constant temperature is maintained thereafter, and the internal pressure of the first sealed space 32 is also increased. Lubricating oil is maintained at an appropriate pressure with no risk of leaking from the oil seal 25 or the like.
Of course, since the second sealed space 57 has a larger internal volume than the first sealed space 32, it is assumed that there is air inflow from the first sealed space 32, even if there is some lubricating oil inflow from the first sealed space 32. However, there is no risk of a high internal pressure that would cause a lubricating oil leak from the oil seal 43 or the like.

  When the robot stops, the air temperature in the first sealed space 32 and the second sealed space 57 decreases. At this time, the plug 67 maintains the state in which the communication path 65 is closed by the spring force of the compression coil spring 68. For this reason, in the state in which the first sealed space 32 and the second sealed space 57 have returned to room temperature, the amount of air in the first sealed space 32 has flowed into the second sealed space 57 as compared to the previous room temperature. The internal pressure of the first sealed space 32 is reduced by the amount. Therefore, even if the operation of the robot is started next, the internal pressure of the first sealed space 32 moves the plug 67 in the direction of arrow A against the spring force of the compression coil spring 68 to open the communication path 65. It won't be so expensive.

  Of course, when the temperature rises more than during the previous operation, it is considered that the communication path 65 may be opened, but such a reopening of the communication path 65 does not occur in normal operation. Therefore, there is very little opportunity to open the communication path 65 in which lubricating oil may flow in and out between the first sealed space 32 and the second sealed space 57, and the first sealed space 32 or the second sealed space 57. It is possible to eliminate as much as possible the danger of running out of lubricating oil.

  As described above, in the present embodiment, when the internal pressure of the first sealed space 32 increases, the communication path 65 is opened and the air in the first sealed space 32 flows into the second sealed space 57. There is no fear that the internal pressure will rise abnormally. For this reason, even if the service life of the oil seal 25 or the O-ring 27 that seals the first sealed space 32 is exceeded, the lubricant leaks from the sealed portion by the oil seal 25 or the O-ring 27. The occurrence of defects can be prevented as much as possible. In addition, even if the air in the first sealed space 32 is communicated with the second sealed space 57 by the communication passage 65, the plug 67 allows the air between the first sealed space 32 and the second sealed space 57. Thus, it is possible to prevent the occurrence of an abnormal situation in which the first speed reduction mechanism 11 and the second speed reduction mechanism 12 are seized.

The present invention is not limited to the embodiment described above and shown in the drawings, and can be expanded or changed as follows.
If the other end of the communication path 65 is opened at a position inside the second flexible external gear 17, it is not necessary to form the connection path 66 in the second rigid internal gear 20.
The O-ring 27 that seals between the first casing 9 and the casing receiver 28 may be mounted on the casing receiver 28 side.
If the O-ring is provided between the outer casing element 39 and the casing receiver 47 in the second casing 10, the two O-rings 46 and 51 of the second rigid internal gear 20 become unnecessary.
The through hole of the second casing 10 is not limited to the screw hole 56.
The first speed reduction mechanism 11 and the second speed reduction mechanism 12 may be composed of a normal gear train.
The components of the first casing 9 and the second casing 10 are not limited to those of the embodiment.

  In the drawings, 1 is an arm, 2 is a frame, 3 is a wrist rotating part, 4 is a flange (end effector mounting member), 5 is a housing, 6 is a motor, 7 is a first reduction device, 8 is a second reduction device, 9 Is a first casing, 10 is a second casing, 11 is a first speed reduction mechanism, 12 is a second speed reduction mechanism, 25 is an oil seal (seal member), 27 is an O-ring (seal member), and 28 is a casing receiver (fitting) Part), 32 is a first sealed space, 43 is an oil seal (seal member), 46 is an O-ring (seal member), 47 is a casing receiver, 49 is an input shaft, 52 and 53 are O-rings (seal members), 54 Is a cover, 55 is a screw, 56 is a screw (through hole), 57 is a second sealed space, 65 is a communication path, 67 is a plug (open / close valve), and 68 is a compression coil spring.

Claims (1)

A wrist device for a robot that includes a rotatable end effector mounting member and rotatably mounts a wrist rotating unit that includes a motor that drives the end effector mounting member on a distal end portion of an arm that includes a motor that drives the wrist rotating unit. In
A first reduction device for the end effector mounting member and a second reduction device for the wrist rotation unit are provided on different surfaces of the housing of the wrist rotation unit,
The first speed reducer and the second speed reducer decelerate the rotation of the motor built in the wrist rotating part and transmit it to the end effector mounting member in the first casing and the second casing, respectively. Comprising a first reduction mechanism and a second reduction mechanism that reduces the rotation of the motor built in the arm and transmits it to the wrist rotation part;
The first casing has one end surface on the housing side open, and a fitting portion provided on one of the different surfaces of the housing has at least one of the fitting portion and the first casing. The inside is a first sealed space by being fitted with a seal member that seals between the two on one side,
The second casing has a through hole that communicates the inside with the outside, and is attached to the other of the different surfaces of the housing, and the through hole is closed after being attached to the housing. The interior is a second sealed space having a larger internal volume than the first sealed space,
A communication path is provided for communicating between the first sealed space in the first casing and the second sealed space in the second casing, and the communication path is always closed, A wrist device for a robot, wherein an open / close valve is provided to open the communication passage when the pressure in the first sealed space is higher than a pressure in the second sealed space by a predetermined value or more.

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