JPWO2008136405A1 - Rotation drive device, robot joint structure and robot arm - Google Patents

Abstract

A sun gear having an annular shape, a planet gear that meshes with the sun gear and revolves around the center axis O of the sun gear, a fixed internal gear that is fixedly arranged coaxially with the sun gear and meshes with the planet gear, And a movable internal gear that has a different number of teeth from that of the toothed gear, is rotatably arranged coaxially with the sun gear, and meshes with the planetary gear, and a drive motor that rotates the sun gear around the central axis. The movable internal gear is provided with a cylindrical output shaft, and this output shaft is held by an annular rotation support member. The drive motor is arranged such that its drive shaft is deviated from the central axis O of the sun gear. A through hole extending along the central axis O is provided on the inner peripheral side of the sun gear.

Description

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

There has been proposed a rotary drive device composed of a speed reducer using a so-called mysterious planetary gear and a drive motor that rotationally drives the sun gear (see, for example, Patent Document 1).
The mysterious planetary gear includes a sun gear, a planetary gear that meshes with the sun gear and revolves around the central axis of the sun gear, and a fixed internal gear that meshes with the planetary gear and is fixedly arranged coaxially with the sun gear. And a movable internal gear that has a different number of teeth from the fixed internal gear, meshes with the planetary gear, and is rotatably arranged coaxially with the sun gear, and outputs to the central portion of the movable internal gear A shaft is provided.

When the sun gear rotates, the planetary gear rotates and revolves around the central axis of the sun gear. Since the fixed internal gear and the movable internal gear that mesh with the planetary gear are configured so that the number of teeth is different, the relative position in the rotational direction of the fixed internal gear and the movable internal gear is determined by the revolution and rotation of the planetary gear. As a result, the movable internal gear rotates around the central axis.
The reduction gear ratio U in the mysterious planetary gear is expressed by the following equation, where the number of teeth of the sun gear is Z1, the number of teeth of the fixed internal gear is Z2, and the number of teeth of the movable internal gear is Z3.
U = ((1 + Z2 / Z1) / (1-Z2 / Z3))
A large reduction ratio can be obtained by reducing the difference between the number of teeth Z2 of the fixed internal gear and the number of teeth Z3 of the movable internal gear.
JP 2000-274495 A

  In the rotary drive device disclosed in Patent Document 1, the drive shaft of the drive motor and the output shaft of the rotary drive device are disposed on the central axis of the sun gear, so that the output shaft is firmly held. A rotation support member could not be arranged, and a highly rigid rotation drive device could not be constructed.

For example, when a rotational drive device having a mysterious planetary gear is used as a joint structure such as a robot arm, a large torque can be obtained even with a small drive motor, and the joint structure can be reduced in size and energy saving.
However, in the rotary drive device described in Patent Document 1, since the output shaft of the rotary drive device is arranged on the central axis of the sun gear, the power cable, the signal cable, etc. are arranged on the outer peripheral side of the output shaft. There is a need.
Therefore, when the output shaft is rotated, the power cable and the signal cable are also moved together, so that wiring is very difficult.

In the joint structure of the robot, a complex operation can be performed by forming an orthogonal two-axis joint structure with two rotational drive devices having orthogonal center axes.
However, in the rotary drive device described in Patent Document 1, the drive motor is disposed on the central axis, and when the two rotary drive devices are brought close to each other, the drive motors interfere with each other. Could not be made compact.

  The present invention has been made in view of the above-described circumstances, and has a high-rigidity rotary drive device that can be easily wired such as a power cable and a signal cable, and a joint structure of a robot using the rotary drive device, and An object of the present invention is to provide a robot arm having the joint structure of the robot.

  In order to solve the above-mentioned problems, a first aspect of the present invention is a rotary drive device, which is an annular sun gear, and meshes with the sun gear and revolves around a center axis of the sun gear. A planetary gear, a fixed internal gear fixedly arranged coaxially with the sun gear, and having a different number of teeth from the fixed internal gear, and rotatable coaxially with the sun gear. A movable internal gear that is disposed and meshes with the planetary gear, and a drive motor that rotates the sun gear around the central axis, and the movable internal gear is provided with a cylindrical output shaft, The output shaft is held by an annular rotation support member, and the drive motor is disposed such that the drive shaft is biased with respect to the central axis of the sun gear, and on the inner peripheral side of the sun gear, center It is characterized in that through-holes extending along the is provided.

  In the rotary drive device having this configuration, the drive motor is disposed so that the drive shaft is biased with respect to the central axis of the sun gear, so that the output shaft provided on the movable internal gear has a large-diameter annular shape. It can be firmly held by the rotation support member. Thereby, rotation of an output shaft (movable internal gear) does not fluctuate, and a highly rigid rotation drive device can be configured. Further, since the drive motors do not interfere with each other, the two rotary drive devices can be assembled close to each other so that their central axes intersect, and the two-axis joint structure can be configured in a small size.

  Furthermore, since a through hole extending along the central axis is provided on the inner peripheral side of the sun gear, a power cable, a signal cable, and the like can be wired along the central axis of the sun gear. Therefore, even if the movable internal gear or the sun gear rotates, the power cable and the signal cable do not move greatly, and wiring can be easily performed.

According to a second aspect of the present invention, in the first aspect, the sun gear is supported by an annular rotation support member.
In this case, since the annular sun gear is supported by the rotation support member, the central axis of the sun gear does not fluctuate, and a highly rigid rotation drive device can be provided.

  According to a third aspect of the present invention, in the first aspect, a plurality of the drive motors are provided. This increases the output of the rotary drive device.

  According to a fourth aspect of the present invention, there is provided a robot joint structure including the two rotational drive devices of the first aspect, wherein the drive motor of one rotational drive device and the drive motor of the other rotational drive device intersect each other. In addition, the center axes of both rotary drive devices intersect each other.

In the joint structure of the robot having this configuration, since the two-axis joint structure is configured by the two rotational drive devices, it is possible to perform a complicated operation. Further, since the drive motors of the two rotary drive devices are arranged so as to cross each other, both rotary drive devices can be brought close to each other, and the joint structure can be downsized.
In addition, by wiring the power cable and the signal cable through the through hole provided in the rotary drive device, even when a complicated operation is performed, these cables do not move greatly, and troubles such as disconnection can be prevented.

According to a fifth aspect of the present invention, there is provided a robot arm including the robot joint structure according to the fourth aspect.
In this case, since the rotary drive device has a mysterious planetary gear with a large reduction ratio, even a small drive motor can output a large torque, and a small and high output robot arm can be constructed. Can do.

According to the present invention, a rotary drive device having high rigidity and easy wiring such as a power cable and a signal cable, a robot joint structure using the rotary drive device, and a robot arm equipped with the robot joint structure are provided. Can be provided.
The above and other objects, operations and effects of the present invention will be apparent to those skilled in the art from the accompanying drawings and description of the embodiments of the present invention.

It is a perspective view which shows the rotational drive apparatus of 1st Embodiment of this invention. It is a front view which shows the rotational drive apparatus of 1st Embodiment. It is a side view which shows the rotational drive apparatus of 1st Embodiment. It is sectional drawing which follows the XX line of FIG. It is sectional drawing which follows the YY line of FIG. It is a schematic perspective view which shows the robot arm of 2nd Embodiment of this invention. It is a schematic perspective view which shows the joint structure of the robot arm of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotation drive apparatus 11 Mounting plate 15 Drive motor 16 Drive shaft 20 Reduction gear 21 Sun gear 22 Ball bearing (rotation support member)
23 planetary gear 24 fixed internal gear 25 movable internal gear 27 output shaft 28 ball bearing (annular rotation support member)
30 Robot arm

Hereinafter, although a plurality of embodiments of the present invention are described, it goes without saying that the present invention is not limited to these embodiments.
With reference to FIGS. 1-5, the rotational drive apparatus 10 of the 1st Embodiment of this invention is demonstrated.
The rotary drive device 10 includes a mounting plate 11, a drive motor 15, and a speed reducer 20 having a so-called wonder planetary gear mechanism.

As shown in FIG. 1, the mounting plate 11 has a substantially rectangular flat plate shape, and four corner portions are provided with bolt holes 12 for mounting.
A reduction gear 20 is disposed on one side (right side in FIGS. 1 and 3) of the mounting plate 11, and a drive motor 15 is disposed on the other side (left side in FIGS. 1 and 3).

The drive motor 15 is disposed such that the rotation center of the drive shaft 16 is deviated from the center axis O of the sun gear 21 (described later).
A pinion 17 having a predetermined number of teeth (Z0) is provided at the tip of the drive shaft 16, and the pinion 17 meshes with the sun gear 21.

Next, the speed reducer 20 will be described with reference to cross-sectional views shown in FIGS.
The reduction gear 20 includes a sun gear 21 that is arranged to be rotatable about a central axis O. The sun gear 21 has an annular shape, and a tooth profile with a predetermined number of teeth (Z1) is formed on the outer peripheral surface thereof. The sun gear 21 is supported by an annular ball bearing 22 disposed on the inner peripheral side thereof.

  On the outer peripheral side of the sun gear 21, a planetary gear 23 having a tooth shape that meshes with the sun gear 21 on the outer peripheral surface is disposed. The planetary gear 23 is configured to revolve around the central axis O along the outer peripheral surface of the sun gear 21 as the sun gear 21 rotates. In the present embodiment, as shown in FIG. 5, the three planetary gears 23 are arranged at equal intervals (120 ° intervals) in the circumferential direction.

On the outer peripheral side of these planetary gears 23, a fixed internal gear 24 and a movable internal gear 25 each having a tooth shape meshing with the planetary gear 23 on the inner peripheral surface are arranged so as to be stacked in the direction of the central axis O.
The fixed internal gear 24 is joined to the mounting plate 11 and is fixed around the central axis O as well. As shown in FIG. 4, the other internal portion of the planetary gear 23 is meshed with the fixed internal gear 24. The number of teeth of the fixed internal gear 24 is Z2.

  The movable internal gear 25 is disposed so as to be rotatable about the central axis O as well. As shown in FIG. 4, one side portion of the planetary gear 23 is meshed with the movable internal gear 25. The number of teeth Z3 of the movable internal gear 25 is configured to be different from the number of teeth Z2 of the fixed internal gear 24 described above. In this embodiment, the difference in the number of teeth is three. A disk portion 26 orthogonal to the central axis O is formed at one end (right side in FIG. 4) of the movable internal gear 25.

A cylindrical output shaft 27 having a central axis O as the center is provided at the center of the disk portion 26. The output shaft 27 is held by an annular ball bearing 28.
The rotational drive device 10 configured as described above is provided with a through hole extending along the central axis O.

Next, the operation of the rotary drive device 10 will be described. As the drive shaft 16 of the drive motor 15 rotates, the sun gear 21 is rotated around the central axis O.
Here, since the number of teeth of the pinion 17 of the drive shaft 16 is Z0 and the number of teeth of the sun gear 21 is Z1, the reduction ratio U1 in this portion is expressed by the following equation.
U1 = Z1 / Z0

As the sun gear 21 rotates, the planetary gear 23 starts to rotate. Here, since the fixed internal gear 24 meshing with the planetary gear 23 is fixed to the mounting plate 11 so as not to rotate, the planetary gear 23 revolves around the central axis O.
In the fixed internal gear 24 and the movable internal gear 25 meshed with the planetary gear 23, the number of teeth Z2 of the fixed internal gear 24 and the number of teeth Z3 of the movable internal gear 25 are different from each other. When revolving once around the axis O, the movable internal gear 25 rotates with respect to the fixed internal gear 24 by the difference in the number of teeth.

The reduction ratio U2 in this portion is expressed by the following equation.
U2 = ((1 + Z2 / Z1) / (1-Z2 / Z3))
Therefore, the reduction ratio U of the entire reduction gear 20 is expressed by the following equation.
U = U1 × U2 = (Z1 / Z0) × ((1 + Z2 / Z1) / (1-Z2 / Z3))

In the rotary drive device 10 having such a configuration, the reduction ratio U becomes very large as described above, so that a very high torque can be obtained even when the small drive motor 15 is used. Therefore, it is possible to provide a high-power and small-sized rotary drive device 10.
Further, since the drive motor 15 is arranged so that the drive shaft 16 is biased with respect to the center axis O of the sun gear 21, the cylindrical output shaft 27 provided on the movable internal gear 25 has a large diameter. The annular ball bearing 28 can be firmly held, and the output shaft 27 does not fluctuate, so that the highly rigid rotary drive device 10 can be configured. Further, since the drive motors 15 do not interfere with each other, the two rotary drive devices 10 can be assembled in close proximity so that the central axes O are orthogonal to each other, and the orthogonal two-axis joint structure can be configured in a small size. .

Further, since the rotation drive device 10 is provided with a through hole extending along the central axis O, a power cable, a signal cable, and the like can be wired along the central axis O of the sun gear 21.
Therefore, even if the movable internal gear 25 and the sun gear 21 are rotated, the power cable and the signal cable do not move greatly, and wiring can be easily performed.

In the first embodiment, since the three planetary gears 23 are arranged on the outer peripheral side of the sun gear 21 at equal intervals (120 ° intervals) in the circumferential direction, the sun gear 21 meshing with the planetary gear 23 and Since the movable internal gear 25 is supported at three points, it is possible to prevent the sun gear 21 and the rotation shaft (center axis O) of the movable internal gear 25 from wobbling.
Further, since the sun gear 21 is held by the annular ball bearing 22 from the inner peripheral side, the wobbling of the center axis O of the sun gear 21 is eliminated, and the highly rigid rotary drive device 10 can be provided.
In the rotary drive device 10 described above, since the sun gear 21 and the movable internal gear 25 are provided on the same axis, misalignment between the axes is unlikely to occur.
In the rotary drive device 10 described above, only one drive motor 15 is provided, but a plurality of drive motors may be provided. In this case, the output of the rotary drive device 10 increases.

Next, a robot arm according to a second embodiment of the present invention will be described with reference to FIGS.
The robot arm 30 includes a robot joint structure incorporating the rotation drive device of the first embodiment.
FIG. 6 is a schematic perspective view of the robot arm 30, and FIG. 7 is a schematic perspective view of the joint structure of the robot arm 30.

  The robot arm 30 includes a first joint portion 41 that connects the first component member 31 and the second component member 32, a second joint portion 42 that connects the second component member 32 and the third component member 33, A third joint portion 43 disposed at the tip of the three component members 33, the first joint portion 41 is a shoulder joint, the second joint portion 42 is an elbow joint, and the third joint portion 43 is a wrist joint. It is equivalent to.

As shown in FIG. 7, the 1st joint part 41, the 2nd joint part 42, and the 3rd joint part 43 are comprised by combining the two rotational drive apparatuses 10 of 1st Embodiment.
More specifically, the drive motors 15a and 15b of one rotary drive device 10a and the other rotary drive device 10b are arranged so as to be biased with respect to the respective central axes Oa and Ob, and these drive motors 15a and 15b. It arrange | positions so that each may cross | intersect on the other side of each attachment plate 11a, 11b. The central axis Oa of one rotational drive device 10a is arranged so as to be orthogonal to the central axis Ob of 10b of the other rotational drive device.

  In the first joint portion 41, the mounting shaft 34 that protrudes upward from the tip of the first component member 31 is connected to the cylindrical output shaft of one rotation drive device 10 a, and the second component member 32 A mounting shaft 35 protruding from the base end side is connected to a cylindrical output shaft of another rotary drive device 10b.

  In the 2nd joint part 42, the hinge axis | shaft 36 is penetrated and connected to the inner peripheral side of the output shaft of the one rotation drive device 10a. A connection member 37 having a U-shape is provided at the tip of the second component member 32, and both ends of the hinge shaft 36 are pivotally supported by the connection member 37. Moreover, the base end part of the 3rd structural member 33 is connected to the output shaft of the other rotational drive apparatus 10b.

  In the third joint portion 43, the hinge shaft 38 is inserted on the inner peripheral side of the output shaft of the one rotary drive device 10a. A connection member 39 having a U-shape is provided at the tip of the third component member 33, and both ends of the hinge shaft 38 are pivotally supported by the connection member 39.

In the robot arm 30 having such a configuration, the two rotation driving devices 10a and 10b are arranged so that the central axes thereof are orthogonal to each other, so that an orthogonal two-axis joint structure is configured and complicated. Operation can be performed.
Further, since these rotary drive devices 10a and 10b are provided with a wonder planetary gear having a large reduction ratio U, a small drive motor can output a large torque, and a small and high output robot. The arm 30 can be configured.

Furthermore, since the drive motors of the two rotary drive devices 10a and 10b are arranged so as to cross each other, the joint structure can be further reduced in size.
In addition, by wiring the power supply cable and the signal cable through the through holes of the rotary drive devices 10a and 10b, even when a complicated operation is performed, these cables do not move greatly, and troubles such as disconnection can be prevented.
By the way, in this 2nd Embodiment, although demonstrated as what provided three planetary gears, there is no restriction | limiting in the number and arrangement | positioning of a planetary gear, One planetary gear may be sufficient. By arranging the plurality of planetary gears at equal intervals in the circumferential direction, the rotation of the sun gear and the movable internal gear can be stabilized.

  While the invention has been described and illustrated in detail with reference to specific embodiments, the description is not meant to be construed in a limiting sense, and other embodiments of the invention It will be apparent to those skilled in the art by reference to the present specification. That is, various modifications of the disclosed embodiments are possible, and thus such modifications can be made without departing from the scope of the invention as set forth in the claims of this application.

  According to the present invention, it is possible to provide a rotary drive device, a robot joint structure, and a robot arm that have high rigidity and are small, compact, and high output.

Claims (5)

A rotary drive device,
A sun gear having an annular shape;
A planetary gear that meshes with the sun gear and revolves around a central axis of the sun gear;
A fixed internal gear fixedly arranged coaxially with the sun gear and meshing with the planetary gear;
The number of teeth different from that of the fixed internal gear, a movable internal gear that is rotatably arranged coaxially with the sun gear and meshes with the planetary gear,
A drive motor for rotating the sun gear around the central axis,
The movable internal gear is provided with a cylindrical output shaft, and this output shaft is held by an annular rotation support member,
The drive motor is arranged such that the drive shaft is deviated from the central axis of the sun gear,
A rotation driving device, wherein a through hole extending along the central axis is provided on an inner peripheral side of the sun gear. The rotary drive device according to claim 1,
The rotary drive device, wherein the sun gear is supported by an annular rotation support member. The rotary drive device according to claim 1,
A rotational drive device comprising a plurality of the drive motors. A robot joint structure,
Including two rotary drive devices according to claim 1;
A robot joint structure characterized in that a drive motor of one rotary drive unit and a drive motor of the other rotary drive unit cross each other, and center axes of both rotary drive units cross each other. A robot arm,
A robot arm comprising the joint structure of the robot according to claim 4.

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