JP2010151269A - Rotating and driving device, articulation structure of robot and robot arm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating and driving device and an articulation structure of a robot using the rotating and driving device which can remove and alleviate a backlash, improve assembling characteristics and prevent the vibration of an output shaft. <P>SOLUTION: The rotating and driving device having a strange planetary gear includes: a first carrier 52 provided so as to be rotatable about a hollow main shaft; a second carrier 53 for supporting the planetary gear 5 so as to be rotatable; a connecting part 54 for connecting the first carrier 52 to the second carrier 53 and guiding the second carrier 53 to the first carrier 52 so as to be freely movable in the direction intersecting orthogonally to the main shaft; and a biasing part 55 for biasing the second carrier 53 to the direction intersecting orthogonally to the main shaft. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotary drive device, a joint structure of a robot constituted by the rotary drive device, and a robot arm.

As a rotational drive device, as disclosed in Patent Document 1, for example, a device including a reduction gear using a so-called wonder planetary gear and a drive motor that rotationally drives a sun gear has been proposed.
The mysterious planetary gear is a sun gear, a planetary gear that meshes with the sun gear and revolves around the main axis of the sun gear, and a stationary gear that meshes with the outside of the planetary gear and is coaxially fixed with the sun gear. An internal gear and a movable internal gear having a different number of teeth from that of the fixed internal gear and meshing with the planetary gear and rotatably disposed coaxially with the sun gear. Is provided with an output shaft that is driven to rotate coaxially with the main shaft.

  When the sun gear rotates, the planetary gear rotates around the main axis of the sun gear while rotating. Here, since the fixed internal gear and the movable internal gear that mesh with the planetary gears are configured to have different numbers of teeth, the rotation of the fixed internal gear and the movable internal gear is caused by the rotation and revolution of the planetary gear. The relative position in the direction is shifted, and the movable internal gear rotates around the main shaft. The speed reducer using the mysterious planetary gear configured as described above is driven by a drive motor, and the output shaft of the movable internal gear or a member connected to the output shaft is driven to rotate.

In such a rotational drive device using a planetary gear, a backlash is set in advance between the planetary gear and the sun gear or the movable internal gear and the fixed internal gear. Drive smoothly.
JP 2000-274495 A

  By the way, conventionally, there is a problem that it is difficult to position the planetary gear with high accuracy between the sun gear, the movable internal gear, and the fixed internal gear. This is due to the fact that the backlash is set slightly larger in advance in order to prevent the apparatus from being stopped or damaged due to poor meshing between the gears. For this reason, conventionally, the backlash between the planetary gear and each gear is large, and the specification value is not satisfied. For example, there is a possibility that the output accuracy may fluctuate in the rotation direction of the main shaft due to the backlash that is set to be large, and the positional accuracy may be reduced.

On the other hand, in order to prevent such wobbling in the rotational direction of the output shaft, a method of improving the processing accuracy of the tooth profile of the meshing portion of each gear and reducing backlash can be considered, but this requires precision processing. Cost is very expensive and processing takes time. Therefore, productivity is poor and the cost is greatly increased.
In addition, the position (center distance) of each planetary gear greatly depends on the machining accuracy of each component, and assembling becomes difficult if the machining accuracy is poor. Furthermore, if the assemblability is poor, for example, the planetary gear moves in the axial direction, the contact between the movable internal gear or the fixed internal gear and the tooth ends occurs, torque loss due to friction occurs, and transmission efficiency decreases. To do.

  The present invention has been made in view of the circumstances as described above. A rotary drive device capable of removing and reducing backlash, improving assemblability, and preventing wobbling of the output shaft, and the rotary drive device. It is an object of the present invention to provide a joint structure of a robot used and a robot arm provided with the joint structure of the robot.

In order to achieve the above object, the present invention provides a sun gear rotatably provided around a main shaft, a planetary gear meshing with the sun gear and revolving around the main shaft, and a coaxially fixed arrangement with the sun gear. And a fixed internal gear that meshes with the planetary gear, and a movable internal tooth that has a different number of teeth from the fixed internal gear and is rotatably arranged coaxially with the sun gear and meshes with the planetary gear. A rotary drive device including a gear, wherein the first carrier is provided rotatably around the main shaft, the second carrier rotatably supports the planetary gear, the first carrier, and the second carrier. A connecting portion that connects the second carrier to the first carrier so as to be movable in a direction orthogonal to the main axis, and the second carrier is orthogonal to the main axis. A construction is adopted and a biasing portion that biases.
By adopting such a configuration, in the present invention, the second carrier that supports the planetary gear is urged in a direction orthogonal to the main shaft, and the planetary gear is always applied to the sun gear or the movable internal gear and the fixed internal gear. It is in a pressed state. Accordingly, backlash between the gears is appropriately removed and reduced, and the output shaft is prevented from wobbling in the rotation direction of the main shaft.

Further, the joint structure of the robot of the present invention is provided with the two rotation driving devices described above, and these two rotation driving devices have the main shaft of one rotation driving device and the main shaft of another rotation driving device. They are assembled so as to cross each other, and are configured to be rotatable in two axial directions.
According to the joint structure of this robot, the two-axis joint structure is constituted by the two rotational drive devices, so that it is possible to perform a complex operation and, for example, a gripping mechanism attached to the tip of the joint structure. The accuracy of the working unit and the like is improved.

  A robot arm according to the present invention is characterized by including the joint structure of the robot described above. In this case, since the rotary drive device has a mysterious planetary gear mechanism with a large reduction ratio, a relatively large torque can be output even with a small drive motor, and a small and high output robot arm is constructed. can do.

  According to the rotary drive device, the robot joint structure and the robot arm according to the present invention, the backlash between the planetary gear and the sun gear or the movable internal gear and the fixed internal gear can be easily and inexpensively removed and reduced. As well as being easy to assemble, the positional accuracy in the rotation direction of the output shaft can be improved.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing a rotary drive device 10 according to an embodiment of the present invention. FIG. 2 is a plan view of the rotary drive device 10 according to the embodiment of the present invention. FIG. 3 is a cross-sectional view in the main axis direction of the rotary drive device 10 according to the embodiment of the present invention. FIG. 4 is a cross-sectional view in a direction orthogonal to the main axis direction of the rotary drive device 10 according to the embodiment of the present invention. FIG. 5 is a partial cross-sectional exploded perspective view of the rotary drive device 10 according to the embodiment of the present invention.

  The rotational drive device 10 of the present embodiment includes a mounting plate 1, a drive motor 2, and a speed reducer 3 including a so-called strange planetary gear mechanism. The mounting plate 1 has a substantially square plate shape. Bolt holes 1a are formed at the corners of the four corners, and through-holes 1b through which the hollow main shaft (main shaft) 8 is attached are penetrated in the central portion in the thickness direction. Is formed (see FIG. 3). A reduction gear 3 is disposed on one side (upper side in FIG. 3) of the mounting plate 1, and a drive motor 2 is disposed on the other side (lower side in FIG. 3).

  The drive motor 2 has a pinion 2 a that rotates around a rotation axis C that extends in the thickness direction of the mounting plate 1. The pinion 2a is configured to rotate around the rotation axis C at a position protruding from the mounting plate 1 toward the one side.

  The speed reducer 3 is arranged coaxially with the sun gear 4, a sun gear 4 that is rotatably provided around the hollow main shaft 8, a plurality of planetary gears 5 that mesh with the sun gear 4 and revolve around the hollow main shaft 8, A fixed internal gear 6 that is fixed to the mounting plate 1 and meshes with the planetary gear 5, and has a different number of teeth from the fixed internal gear 6, and is arranged coaxially with the sun gear 4 and is freely rotatable. 5 and a plurality of planetary gears 5 are rotatably supported and biased in a direction orthogonal to the main axis direction along the central axis O of the hollow main shaft 8 (a direction orthogonal to the main shaft). Power unit 50.

  The hollow main shaft 8 has a substantially cylindrical shape protruding in the thickness direction of the mounting plate 1, and one end thereof is fixed at a position corresponding to the insertion hole 1b. The inner diameter of the hollow main shaft 8 and the inner diameter of the insertion hole 1b of the mounting plate 1 are the same, and the inner peripheral surface of the hollow main shaft 8 and the inner peripheral surface of the insertion hole 1b are smoothly connected in the main shaft direction. A lock nut 8 a is attached to the other end portion of the hollow main shaft 8, and the relative positional relationship in the main shaft direction of the sun gear 4, the planetary gear 5, and the movable internal gear 7 with respect to the step portion 8 b provided on one end portion side. To regulate.

The sun gear 4 is rotatably provided around the hollow main shaft 8 via the bearing 40A and the bearing 40B. A ring-shaped collar 40C is disposed between the bearing 40A and the bearing 40B, and the two are separated by a predetermined distance in the main shaft direction and the relative positional relationship is restricted. Deep groove ball bearings are used for the bearings 40A and 40B of the present embodiment.
The sun gear 4 has a first gear part 41 and a second gear part 42. The diameter of the first gear part 41 is larger than the diameter of the second gear part, and the number of teeth of the first gear part 41 is larger than the number of teeth of the second gear part 42. The first gear portion 41 is meshed with the pinion 2 a on the outer peripheral side, and rotates around the hollow main shaft 8 by the rotational drive of the drive motor 2. The second gear portion 42 is fixed integrally with the first gear portion 41 and rotates together with the first gear portion 41.

A plurality (three in this embodiment) of planetary gears 5 are provided on the outer peripheral side of the second gear portion 42 (see FIG. 4). The planetary gears 5 are arranged at equal intervals (120 ° intervals) in the circumferential direction. The planetary gear 5 is biased in a direction orthogonal to the main shaft by a biasing unit 50 (described later) provided rotatably around the hollow main shaft 8 via a bearing 51. A ring-shaped collar 50C is disposed between the bearing 51 and the bearing 40B, and both are separated by a predetermined distance in the main shaft direction and the relative positional relationship is restricted. A deep groove ball bearing is used as the bearing 51 of the present embodiment.
Outside the planetary gear 5, a fixed internal gear 6 and a movable internal gear 7 meshing with the planetary gear 5 on the inner peripheral surface overlap with each other in the main shaft direction, and each substantially overlaps the planetary gear 5 in the main shaft direction. They are arranged so that they are half-engaged.

One end of the fixed internal gear 6 in the main axis direction is fixed to the mounting plate 1. On the other hand, a bearing 60 for rotatably supporting the movable internal gear 7 around the central axis O is provided on the inner peripheral side of the other end in the main axis direction of the fixed internal gear 6. A cross roller bearing is used for the bearing 60 of the present embodiment.
The movable internal gear 7 has a different number of teeth from the fixed internal gear 6, and the difference in the number of teeth is set to 3 in this embodiment. An output plate 71 is screwed onto the upper surface in the main axis direction of the movable internal gear 7. The output plate 71 has a substantially ring shape in plan view, and the diameter of the opening 71 a is designed to be larger than the diameter of the lock nut 8 a that is screwed into the hollow main shaft 8.

Next, the configuration of the urging unit 50 will be described in detail with reference to FIGS.
FIG. 6 is a perspective view showing the urging unit 50 according to the embodiment of the present invention. FIG. 7 is a plan view and a sectional view taken along line AA of the urging unit 50 according to the embodiment of the present invention. 8 to 10 are partially exploded perspective views of the urging unit 50 according to the embodiment of the present invention.

  The urging unit 50 connects a first carrier 52 rotatably provided around the hollow main shaft 8, a second carrier 53 rotatably supporting the planetary gear 5, and the first carrier 52 and the second carrier 53. In addition, a connecting portion 54 that guides the second carrier 53 movably in a direction orthogonal to the main axis with respect to the first carrier 52, and an urging portion 55 that urges the second carrier 53 in a direction orthogonal to the main axis. Have.

  The first carrier 52 has a substantially equilateral triangular shape in plan view having a flat side surface 52a perpendicular to the direction orthogonal to the main axis, and an opening 521 into which the bearing 51 is fitted is formed at the center thereof (FIG. 7). And FIG. 9). A step 522 having a smaller diameter than the outer diameter of the bearing 51 is formed in the opening 521. Each apex portion (corner portion) of the first carrier 52 is provided with a clamping member 523 that clamps the outer ring side of the bearing 51 with respect to the stepped portion 522 in the main axis direction. The clamping member 523 is screwed to the first carrier 52 via a screw member 524 inserted in the main axis direction.

The connecting portion 54 has a shaft (track body) 541 that protrudes vertically from the flat side surface 52a, and a ball cage (moving body) 542 that guides the second carrier 53 movably along the shaft 541 (FIG. 9). And FIG. 10). The shaft 541 and the ball cage 542 are each paired in a total of two rows, more specifically, at symmetrical positions across a line connecting the rotation axis of the planetary gear 5 supported by the second carrier 53 and the central axis O. Each is arranged.
The shaft 541 has a substantially cylindrical shape. A plurality of balls (rolling elements) (not shown) are provided on the inner periphery of the ball cage 542. The ball cage 542 moves along the shaft 541 when a ball (not shown) rolls between the inner peripheral surface of the ball cage 542 and the outer peripheral surface of the cylindrical shaft 541. Since the shaft 541 is attached to the flat side surface 52a of the first carrier 52, it is easy to provide guidance accuracy in the direction orthogonal to the main axis, and thereby the planetary gear 5 can be biased in the direction orthogonal to the main axis with high accuracy. It becomes.

  An opening 532 into which the ball cage 542 is fitted is formed in the flat side surface 53a of the second carrier 53 facing the flat side surface 52a. An opening 534 through which the shaft 533 that supports the planetary gear 5 is inserted is formed at the center of the second carrier 53 (see FIGS. 7 and 8). A stepped portion 536 having a diameter smaller than the outer diameter of the bearing 535 that rotatably supports the shaft 533 is formed in the opening 534. The second carrier 53 is provided with a clamping member 537 that clamps the outer ring side of the bearing 535 with respect to the step portion 536 in the main axis direction. The clamping member 537 is screwed to the second carrier 53 via a pair of screw members 538 that are provided across the opening 534 and inserted in the main axis direction.

  The urging unit 55 includes a pair of coil springs 551 provided between the first carrier 52 and the second carrier 53 (see FIGS. 9 and 10). The coil springs 551 are arranged in pairs at symmetrical positions across a line connecting the rotation axis of the planetary gear 5 supported by the second carrier 53 and the central axis O. One end of the coil spring 551 is inserted and fixed in a groove 52 a 1 provided perpendicular to the flat side surface 52 a of the first carrier 52. On the other hand, the other end of the coil spring 551 is inserted into and fixed to a groove 53 a 1 provided perpendicular to the flat side surface 53 a of the second carrier 53. The positions of the groove 52a1 and the groove 53a1 coincide with each other in the facing direction of the first carrier 52 and the second carrier 53.

Next, the assembly operation (attachment / detachment operation) of the urging unit 50 having the above-described configuration with respect to the rotation driving device 10 and the driving and operation of the rotary driving device 10 including the urging unit 50 having the above-described configuration will be described.
When the urging unit 50 is removed from the rotary drive device 10 for maintenance, first, as shown in FIG. 5, the output plate 71 and the movable internal gear 7 are unscrewed to remove the output plate 71. Next, the hollow main shaft 8 and the lock nut 8a are unscrewed, and the lock nut 8a is removed. By removing the lock nut 8a, the restriction (fixation) in the main shaft direction of the bearing 51 is released, so that the urging unit 50 can be easily removed from the hollow main shaft 8. In addition, since the first carrier 52, the second carrier 53, the connecting portion 54, the urging portion 55, and the planetary gear 5 are unitized in the urging unit 50, each component is separated during removal. It can be removed without breaking.

When attaching the urging unit 50 to the rotary drive device 10, the reverse procedure of removal is performed.
First, the bearing 51 is fitted into the hollow main shaft 8, and the urging unit 50 is slid in the main shaft direction. At this time, the second carrier 53 is pressed against the first carrier 52 side, and the coil spring 551 is contracted and slid. When the inner ring side of the bearing 51 comes into contact with the collar 50C (when the planetary gear 5 is positioned between the sun gear 4, the fixed internal gear 6 and the movable internal gear 7), the press of the second carrier 53 is released. . By the release of the presser, the planetary gear 5 moves to the outer diameter side in the direction orthogonal to the main shaft by the restoring force of the coil spring 551 and presses against the fixed internal gear 6 and the movable internal gear 7. The second carrier 53 moves only in the direction orthogonal to the main axis by the connecting portion 54. Furthermore, since they are integrated into a unit, they can be easily attached while maintaining the relative positions of the planetary gears 5 (at intervals of 120 ° in the circumferential direction).

  Next, the lock nut 8a is screwed into the hollow main shaft 8, and the inner ring side of the bearing 51 is sandwiched between the collar 50C and the urging unit 50 is fixed (see FIG. 3). This fixing restricts the position (inclination) of the first carrier 52 in the main axis direction to be constant, so that the second carrier 53 connected to the first carrier 52 and the planetary gear 5 supported by the second carrier 53 are in the main axis direction. Staggering is prevented. Therefore, the planetary gear 5 can be urged with high accuracy in a direction perpendicular to the main shaft, and the meshing failure between the gears due to the inclination can be prevented. Finally, the output plate 71 is screwed onto the movable internal gear 7 to complete the attachment.

Next, the operation of the rotary drive device 10 will be described.
As shown in FIG. 3, when the drive motor 2 rotates the pinion 2 a around the rotation axis C, the pinion 2 a rotates the first gear portion 41 of the sun gear 4 around the central axis O. Here, since the number of teeth of the first gear portion 41 is set to be larger than the number of teeth of the pinion 2a, the rotation of the pinion 2a is decelerated and transmitted to the first gear portion 41.

  When the first gear portion 41 rotates around the central axis O, the second gear portion 42 integrated with the first gear portion 41 rotates around the central axis O and the planetary gear 5 rotates. Here, since the number of teeth of the first gear portion 41 is set to be larger than the number of teeth of the second gear portion 42, the rotation of the pinion 2 a is further decelerated and transmitted to the planetary gear 5. When the planetary gear 5 rotates, the fixed internal gear 6 that meshes with the planetary gear 5 is fixed to the mounting plate 1, so that the planetary gear 5 moves around the central axis O along the outer periphery of the second gear portion 42. Revolve.

  Here, the fixed internal gear 6 and the movable internal gear 7 meshing with the planetary gear 5 are set with different numbers of teeth formed on the inner peripheral surfaces thereof. When revolving around one turn, the movable internal gear 7 rotates relative to the fixed internal gear 6 around the central axis O by the difference in the number of teeth. Thus, when the movable internal gear 7 rotates about the central axis O, the output plate 71 integrated with the movable internal gear 7 rotates about the central axis O.

  Each planetary gear 5 is given a biasing force in a direction perpendicular to the main shaft by a biasing portion 55. As a result, each planetary gear 5 is biased outward from the central axis O, and is always pressed against the movable internal gear 7 and the fixed internal gear 6. Therefore, since the backlash provided in advance between the planetary gear 5 and the movable internal gear 7 and the fixed internal gear 6 is appropriately removed and reduced, the wobbling of the output shaft is prevented.

  Further, even when the driving motor 2 is stopped and the driving force is not transmitted to the movable internal gear 7, the output shaft of the output plate 71 connected to the movable internal gear 7 rotates in the rotational direction around the central axis O. A stable state is achieved without wobbling, and the positional accuracy is improved. That is, the planetary gear 5 in the drive stop state is always pressed against the movable internal gear 7 and the fixed internal gear 6, and the fixed internal gear 6 is fixed to the mounting plate 1. The movable internal gear 7 is fixed.

In addition, a second carrier 53, a connecting portion 54, and an urging portion 55 are provided for each of the planetary gears 5 so that the plurality of planetary gears 5 are always pressed in a direction perpendicular to the main shaft. Therefore, the reaction force of the urging force acting on each planetary gear 5 is balanced, and a high positional accuracy can be obtained.
Furthermore, by arranging the planetary gears 5 at equal intervals in the circumferential direction around the main shaft, higher positional accuracy can be obtained, and wobbling in the rotational direction of the output shaft can be more reliably prevented.

  Therefore, according to the above embodiment, the sun gear 4 provided rotatably around the hollow main shaft 8, the planetary gear 5 meshing with the sun gear 4 and revolving around the hollow main shaft 8, and the sun gear 4 are coaxial. A fixed internal gear 6 that is fixedly arranged and meshes with the planetary gear 5, and has a different number of teeth from the fixed internal gear 6, is rotatably arranged coaxially with the sun gear 4 and meshes with the planetary gear 5. The rotary drive device 10 includes a movable internal gear 7, and includes a first carrier 52 that is rotatably provided around the hollow main shaft 8, a second carrier 53 that rotatably supports the planetary gear 5, and a first carrier. 52 and the second carrier 53 are coupled to each other and the second carrier 53 is guided to the first carrier 52 so as to be movable in a direction perpendicular to the main axis. The backlash between the planetary gear 5 and the movable internal gear 7 and the fixed internal gear 6 can be easily and inexpensively removed by adopting the configuration in which the biasing portion 55 that biases in the direction orthogonal to the In addition to being able to reduce, the assemblability is good, and the effect of improving the positional accuracy of the output shaft in the rotation direction can be obtained.

Next, a robot joint structure 100 using the above-described rotation driving device 10 and a robot arm 200 including the same will be described.
FIG. 11 is a perspective view showing a joint structure 100 of a robot using the rotary drive device 10 according to the embodiment of the present invention. FIG. 12 is a perspective view showing a robot arm using the joint structure 200 of the robot shown in FIG.
In addition, the same code | symbol is attached | subjected to the same member as above-mentioned embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 11, the joint structure 100 of the robot is configured by using the two rotational drive devices 10 described above. The joint structure 100 of the robot includes a drive motor 2 of one rotary drive device 10a (left side in FIG. 11) and a drive motor 2 of another rotary drive device 10b (right side in FIG. 11). And the central axis O of one rotary drive device 10a and the central axis O of the other rotary drive device 10b are arranged so as to cross each other. It is configured to be rotatable in two axial directions. Specifically, in these rotational drive devices 10 a and 10 b, the central axes O are orthogonal to each other, and side portions facing each other on the outer peripheral surface of each mounting plate 1 are in contact with each other.

  According to the joint structure 100 of the robot configured as described above, since the two-axis joint structure is configured by the two rotation driving devices 10a and 10b, a complicated operation can be performed. Further, since the drive motors 2 of the two rotary drive devices 10a and 10b are arranged so as to cross each other, the rotary drive devices 10a and 10b can be brought closer to each other, and the robot joint structure 100 can be downsized. Can be achieved.

  Also, as shown in FIG. 12, the robot arm 200 connects the first joint portion 30a that connects the first component member 201 and the second component member 202, and the second component member 202 and the third component member 203. The second joint portion 30b, and the third joint portion 30c disposed at the tip of the third component member 203. The robot arm 200 corresponds to a first joint portion 30a corresponding to a shoulder joint, a second joint portion 30b corresponding to an elbow joint, and a third joint portion 30c corresponding to a wrist joint. The third joint portions 30a, 30b, and 30c are formed by the above-described robot joint structure 100, respectively.

  In the first joint portion 30a, a mounting shaft 201a that protrudes upward from the end portion of the first component member 201 is connected to the output plate 71 of the single rotation drive device 10a. In addition, an attachment shaft 202a that protrudes from the base end of the second component member 202 toward the first component member 201 is connected to an output plate 71 of another rotation drive device 10b.

  In the second joint portion 30 b, the hinge shaft 204 is inserted into the radial direction inside the output plate 71 of one rotation driving device 10 a and is connected to the output plate 71. A connecting member 205 having a substantially U-shaped cross section or a substantially C-shaped cross section is provided at the tip of the second component member 202, and both end portions of the hinge shaft 204 are pivotally supported by the connecting member 205. Further, the base end portion of the third component member 203 is connected to the output plate 71 of the other rotational drive device 10b.

  In the third joint portion 30 c, the hinge shaft 206 is inserted into the radial direction inner side of the output plate 71 of one rotation driving device 10 a and connected to the output plate 71. Further, a connecting member 207 having a substantially U-shaped cross section or a substantially C-shaped cross section is provided at the tip of the third component member 203, and both end portions of the hinge shaft 206 are pivotally supported by the connecting member 207.

  The robot arm 200 configured as described above is arranged so that the two rotation driving devices 10a and 10b are orthogonal to each other in the first, second, and third joint portions 30a, 30b, and 30c. As a result, an orthogonal two-axis joint structure is formed, and a complicated operation can be performed.

  In addition, since these rotary drive devices 10a and 10b are composed of a wonder planetary gear mechanism having a large reduction ratio, a relatively large torque can be output even if the small drive motor 2 is used. A small and high-torque robot arm 200 can be configured.

Furthermore, since the drive motors 2 of the two rotary drive devices 10a and 10b are arranged so as to cross each other, the joint structure can be further miniaturized.
Moreover, since the rotational drive apparatuses 10a and 10b can insert wiring members, such as a power cable and a signal cable, inside the hollow main shaft 8 on the radially inner side in each output plate 71, the apparatus performs a complicated operation. However, these wiring members do not move greatly, so that the wiring members can be easily handled and can be prevented from being damaged.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the present embodiment, it has been described that the urging unit 50 urges the planetary gear 5 to the outer diameter side in the direction orthogonal to the main shaft to press the movable gear 7 and the fixed internal gear 6. Depending on how the driving device 10 is used, the sun gear 4 is on the output side. In this case, the urging unit 50 may be configured such that the planetary gear 5 is urged toward the inner diameter side in the direction orthogonal to the main shaft and pressed against the sun gear 4. In this case, for example, the coil spring 551 is assembled so as to give a tensile force.

  For example, in the present embodiment, it has been described that three planetary gears 5 are provided. However, the present invention is not limited to this configuration, and for example, a configuration in which a plurality of planetary gears 5 are provided may be used. In this case, since the first carrier 52 preferably has flat side surfaces 52a corresponding to the number of planetary gears 5, the design is changed to, for example, a substantially square shape in plan view or a substantially regular pentagonal shape in plan view.

It is a perspective view which shows the rotational drive apparatus in embodiment of this invention. It is a top view of the rotation drive device in an embodiment of the invention. It is sectional drawing in the principal axis direction of the rotational drive apparatus in embodiment of this invention. It is sectional drawing in the direction orthogonal to the main-axis direction of the rotational drive apparatus in embodiment of this invention. It is a partial section exploded perspective view of the rotation drive device in an embodiment of the invention. It is a perspective view which shows the urging | biasing unit in embodiment of this invention. It is the top view and linear AA sectional drawing of the urging | biasing unit in embodiment of this invention. It is a partial exploded perspective view of the energizing unit in an embodiment of the invention. It is a partial exploded perspective view of the energizing unit in an embodiment of the invention. It is a partial exploded perspective view of the energizing unit in an embodiment of the invention. It is a perspective view which shows the joint structure of the robot using the rotational drive apparatus in embodiment of this invention. It is a perspective view which shows the robot arm using the joint structure of the robot in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 4 ... Sun gear, 5 ... Planetary gear, 6 ... Fixed internal gear, 7 ... Movable internal gear, 8 ... Hollow main shaft (main shaft) 10, 10a, 10b ... Rotary drive device, 30a ... 1st joint part (robot 30b ... second joint (robot joint structure), 30c ... third joint (robot joint structure), 51 ... bearing (bearing part), 52 ... first carrier, 52a ... flat side surface, 53 ... Second carrier, 54 ... Connecting portion, 55 ... Biasing portion, 100 ... Robot joint structure, 200 ... Robot arm, 541 ... Shaft (track body), 542 ... Ball cage (moving body), O ... Center axis

Claims (8)

A sun gear rotatably provided around the main shaft, a planet gear that meshes with the sun gear and revolves around the main shaft, and a fixed internal gear that is fixedly arranged coaxially with the sun gear and meshes with the planet gear And a rotational drive device comprising a movable internal gear having a different number of teeth from the fixed internal gear and being rotatably arranged coaxially with the sun gear and meshing with the planetary gear,
A first carrier rotatably provided around the main axis;
A second carrier that rotatably supports the planetary gear;
A connecting portion that connects the first carrier and the second carrier to each other and guides the second carrier with respect to the first carrier so as to be movable in a direction perpendicular to the main axis;
And a biasing portion that biases the second carrier in a direction perpendicular to the main shaft.   The said 1st carrier, the said 2nd carrier, the said connection part, the said urging | biasing part, and the said planetary gear are unitized so that attachment or detachment is possible integrally. Rotation drive device.   The rotary drive device according to claim 1, wherein the first carrier is rotatably attached to the main shaft via a bearing portion fixed in the main shaft direction. The first carrier has a flat side surface perpendicular to a direction orthogonal to the main axis,
The said connection part has the track body which protrudes in the orthogonal | vertical direction from the said flat side surface, and the mobile body which guides the said 2nd carrier along the said track body so that movement is possible. The rotational drive apparatus as described in any one. A plurality of the planetary gears;
The rotary drive device according to any one of claims 1 to 4, wherein the second carrier, the coupling portion, and the urging portion are provided for each of the plurality of planetary gears. A plurality of the planetary gears;
The rotary drive device according to any one of claims 1 to 5, wherein the planetary gears are arranged at equal intervals in a circumferential direction around the main shaft.   Two rotation drive devices according to any one of claims 1 to 6 are provided, and the two rotation drive devices mutually connect the main shaft of one rotation drive device and the main shaft of another rotation drive device. A joint structure of a robot, which is arranged so as to intersect with each other and is configured to be rotatable in two axial directions.   A robot arm comprising the joint structure of the robot according to claim 7.

Images