JP2011127737A - Rotary damper and robot joint driving device including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary damper quickly damping vibration caused by fluctuation of a driving torque while stopping operation without hampering normal operation of a robot and shortening a task time of work, even if it is used for a joint of the robot with reduced output and having a flexible structure. <P>SOLUTION: The rotary damper includes a base member, a rotary member rotatably arranged around a predetermined axis with respect to the base member, a friction member fixed to at least either the base member or the rotary member and pressed to the other to slidably contact the other for giving frictional braking force to relative rotation of the rotary member with respect to the base member, a pressing means for applying pressing force on the friction member toward the other, and a pressing force changing means for reducing the pressing force applied on the friction member when rotation speed of the rotary member is increased. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rotary damper suitable for use in a joint of a robot and the like, and particularly to a rotary damper having a higher rotational resistance as the rotational speed is lower. The present invention also relates to a rotary robot joint drive device including the rotary damper.

  When causing the robot to perform work, it is necessary to set the distance between the workpiece and the hand within a predetermined accuracy in the step of bringing the robot hand close to the workpiece and the step of separating the robot hand from the workpiece. On the other hand, a rotary system robot joint drive device has a load moment of inertia and a structural torsional rigidity, and vibration is generated due to fluctuations in drive torque when the operation is stopped or started. For this reason, conventionally, this vibration has been suppressed by making the robot structure highly rigid.

  By the way, in recent years, cases where people and robots coexist and collaborate are increasing, and in order to ensure the safety of robots against such people, reducing the output of the robot is an essential solution. However, if the output of the robot is reduced, the rigidity of the structure is inevitably reduced, and the vibration amplitude increases as a so-called flexible robot.

  In particular, when the position of the workpiece is confirmed with high accuracy by the imaging device in order to set the distance between the workpiece and the predetermined accuracy, it is desirable to equip the imaging device with or near the robot hand. In some cases, it is necessary to keep the vibration of the hand below the amplitude required by the imaging device, and from the task time of the work, the vibration settling time must be within an allowable time. Therefore, in order to attenuate the vibration of the hand, a mechanism for attenuating the vibration of the robot joint drive device is required. Conventionally, for example, an oil-type rotary damper (rotary damper) described in Non-Patent Document 1 is known as such a vibration damping mechanism of a rotating system.

Refer to the product information Rotary Damper and Hinge Damper of Precision Equipment Division on Fuji Latex Co., Ltd. homepage downloaded on October 19, 2009 (http://www.fujilatex.co.jp/seimitsukiki/data/product/r-dumper -structure.pdf)

  However, since the conventional rotary damper described above uses the braking force generated by the viscous resistance of oil, the rotational resistance increases as the rotational speed increases. For this reason, if it is provided in a robot joint drive device of a rotating system. However, there is a problem that during normal operation in which the operation speed of the robot increases, the rotational resistance increases and energy loss increases, and the normal operation is hindered when the output of the robot is reduced.

  Therefore, the present invention quickly attenuates vibrations caused by fluctuations in drive torque at the time of stopping or at the start of operation without interfering with the normal operation of the robot even when used for the joints of flexible robots with reduced output. An object of the present invention is to provide a rotary damper capable of shortening the task time of work, and a rotary robot joint drive device including the rotary damper.

  The present invention advantageously solves the above-described problems, and a rotary damper according to the present invention includes a base member, a rotary member arranged to be rotatable around a predetermined axis with respect to the base member, the base member, and the rotation A friction member fixed to at least one of the members and pressed toward the other to be in sliding contact with the other, and applying a friction braking force to the relative rotation of the rotating member with respect to the base member; and the other to the friction member A pressing means for applying a pressing force toward the head, and a pressing force changing means for reducing the pressing force applied to the friction member when the rotational speed of the rotating member increases.

  The robot joint drive device according to the present invention is a drive device provided at a joint connecting two link members of a robot, wherein a motor and an input shaft are drivingly coupled to an output shaft of the motor, A speed reducer that rotates one of the two link members with respect to the other by an output rotation obtained by reducing the rotation of the output shaft, and an output shaft of the motor or an input shaft of the speed reducer and one of the two link members. The rotary damper provided between them to brake the rotation of the shaft against one of the link members.

  In the above-described rotary damper of the present invention, the friction member fixed to at least one of the base member and the rotary member arranged to be rotatable around a predetermined axis with respect to the base member is rotated with the base member. Pressed by the pressing means toward the other of the members and slidably contacted in the other direction to give a friction braking force to the relative rotation of the rotating member with respect to the base member, and the pressing force changing means increases the rotation speed of the rotating member And the pressing force applied to the friction member is reduced to reduce the friction braking force of the friction member.

  Therefore, according to the rotary damper of the present invention, when it is provided in a rotary system robot joint drive device, vibration is suppressed with a high braking force at the time of operation stop and operation start when the operation speed of the joint is low, while the operation of the joint is During normal operation at higher speeds, the braking force decreases, and the rotational resistance decreases and energy loss decreases, so even if it is used for a flexible robot joint with reduced output, normal operation of the robot is not hindered. In addition, it is possible to quickly attenuate the vibration due to the fluctuation of the driving torque when the operation is stopped, and to shorten the task time of the work. In addition, since the braking force is applied to the joint even when the joint is stopped, the arm of the robot can be maintained at the stop position without providing a separate brake.

  In the rotary damper of the present invention, the pressing force changing means may reduce the pressing force using a centrifugal force applied to a weight member that rotates around the axis as the rotating member rotates. In this way, the pressing force of the pressing means can be reduced by a mechanical configuration, so that the pressing force changing means can be configured at low cost.

  In the rotary damper of the present invention, the pressing means applies a pressing force to the friction member toward the other in the axial direction, and the pressing force changing means includes a steel ball as the weight member, A disk-shaped member as a base member having a frustoconical concave surface centered on the axis, which is in contact with a steel ball, and the disk-shaped member exerts a centrifugal force applied to the steel ball The concave surface may be converted into the axial force, and the axial force may be used to press the rotating member in a direction away from the disk-shaped member. Can be configured.

  On the other hand, in the robot joint drive device of the present invention described above, the output shaft of the motor provided at the joint connecting the two link members of the robot or the input shaft provided at the joint is used as the output shaft of the motor. Is provided between an input shaft of a speed reducer that rotates one of the two link members with respect to the other by an output rotation reduced in rotation of the output shaft of the motor and one of the two link members. When the rotational speed of the output shaft of the motor or the input shaft of the speed reducer increases, the rotary damper of the above invention reduces the braking force applied to the one link member on the shaft.

  Therefore, according to the robot joint drive device of the present invention, the normal operation of increasing the operation speed by suppressing vibration with a high braking force when the operation speed of the joint connecting the two link members of the robot is low or at the start of the operation is suppressed. Since the braking force is reduced and the rotational resistance is reduced and the energy loss is reduced, even when used for flexible robot joints with reduced output, normal operation of the robot is not interrupted or activated without interfering with normal operation of the robot. The vibration due to the fluctuation of the driving torque at the start can be quickly attenuated, and the task time of the work can be shortened. In addition, since the braking force is applied to the joint even when the joint is stopped, the arm of the robot can be maintained at the stop position without providing a separate brake.

It is sectional drawing which shows one Example of the rotation damper of this invention. (A) And (b) is a perspective view which shows the external appearance of the rotary damper of the said Example from the back side and a front side, respectively. (A) And (b) is a perspective view which cuts off some external appearances of the rotary damper of the said Example, and each shows from a back side and a front side. (A) And (b) is a disassembled perspective view which shows the rotary damper of the said Example from the back side and the front side, respectively. It is a characteristic view which shows the relationship between the rotation speed of the rotation damper of the said Example, and damping torque. (A), (b) and (c) are front views illustrating a working robot equipped with a shoulder joint drive device as an embodiment of the robot joint drive device of the present invention, to which the rotary damper of the above embodiment is mounted. FIG. 2 is a side view and a perspective view. (A), (b) and (c) are the side view of the whole arm which shows the structure of the shoulder joint drive device of the said Example, a front view, and a perspective view. It is sectional drawing which follows the DD line | wire of Fig.7 (a) which shows the structure of the shoulder joint drive device of the said Example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the rotary damper according to the present invention, and FIGS. 2A and 2B are perspective views showing the appearance of the rotary damper of the embodiment from the back side and the front side, respectively. 3 (a) and 3 (b) are perspective views showing the appearance of the rotary damper of the above embodiment with a part cut away from the back side and the front side, respectively, and FIGS. 4 (a) and 4 (b) are views of the rotation of the above embodiment. It is a disassembled perspective view which shows a damper from a back side and a front side, respectively.

  As shown in FIG. 1, the rotary damper of this embodiment includes a control disk 1 as a base member and a disk-shaped member, and a rotary member disposed so as to be rotatable around a predetermined central axis C with respect to the control disk 1. The rotating disk 2 and the control disk 1 and the rotating disk 2 are fixed to the rotating disk 2 and pressed against the control disk 1 so as to be in sliding contact with the control disk 1 and rotate relative to the control disk 1. A sliding ring 3 as a friction member that gives a friction braking force to the relative rotation of the disk 2, a highly elastic washer 4 as a pressing means that applies a pressing force to the sliding ring 3 toward the control disk 1, and rotation A pressing force changing mechanism 5 is provided as pressing force changing means for reducing the pressing force applied to the sliding ring 3 when the rotational speed of the disk 2 increases.

  As shown in FIGS. 2 to 4, the control disk 1 is fitted into a substantially circular lid-like cover 6 and fixed to the cover 6 with a fastening screw (not shown). Further, a toothed pulley 7 around which a toothed belt is wound is fixed by bolts 8 on the outer surface of the rotating disk 2, and the sliding ring 3 is formed on the inner surface of the rotating disk 2. It is fixed to the rotary disk 2 in a state of being fitted and positioned in the annular groove 2a. In this embodiment, the sliding ring 3 has a large amount of elastic deformation in the axial direction made of synthetic rubber. However, the sliding ring 3 may have a small or little amount of elastic deformation in the axial direction, such as a carbon ring.

  Two outer peripheral flanges 2b and 2c are formed on the outer peripheral portion of the rotary disk 2 so as to be aligned in the axial direction of the central axis C and extend outward in the radial direction. In 2b, a large number of U-shaped ball receiving grooves 2d opened outward in the radial direction are formed at intervals in the circumferential direction. Steel balls 9 as weights are accommodated in the ball receiving grooves 2d, respectively. These steel balls 9 are covered from the outside in the radial direction by the cover 6 and are prevented from coming off in the radial direction. At the same time, the outer peripheral flange 2c on the outer surface side covers the center axis C from the outside in the axial direction.

  A shallow frustoconical concave surface 1a centering on the central axis C is formed on the outer peripheral portion of the inner surface side of the control disk 1, and each steel ball 9 is formed in the concave surface 1a in the ball receiving groove 2d. It can move inward and outward in the radial direction with respect to the central axis C while abutting. Further, an annular sliding contact surface 1b extending in the radial direction about the central axis C is formed at a portion facing the sliding ring 3 on the inner surface side of the control disk 1, and the sliding ring 3 is In the stationary state of the rotating disk 2 where the centrifugal force does not act on the steel ball 9, the steel ball 9 is in contact with the sliding contact surface 1b.

  A through hole 1c having an inner peripheral flange at the inner end is formed in the central portion of the control disk 1, and an outer race 10a of the bearing 10 is fitted into the through hole 1c. Further, a concave portion 2e recessed from the outer surface of the rotary disk 2 and a through hole 2f are formed in the central portion of the rotary disk 2, and an outer peripheral flange 11a accommodated in the concave portion 2e is formed in the through hole 2f. A pressing shaft 11 having one end portion is slidably inserted in the central axis C direction, and the other end portion of the pressing shaft 11 is slidable in the inner race 10b of the bearing 10 in the central axis C direction. While being inserted, a female screw 11b is formed at the center.

  A pressing washer 13 is attached to the other end portion of the pressing shaft 11 via a positioning screw 12 screwed to the female screw 11 b. The pressing washer 13 is an outer end surface of the inner race 10 b of the bearing 10. Abut. The high-elastic washer 4 described above is interposed between the outer peripheral flange 11 a of the pressing shaft 11 and the recess 2 e of the rotary disk 2.

  As a result, when the positioning screw 12 is screwed into the female screw 11 b of the pressing shaft 11, the pressing shaft 11 is attracted to the control disk 1 by the screw thrust via the pressing washer 13 and the bearing 10, and the outer periphery of the pressing shaft 11. The flange 11a compresses the highly elastic washer 4 with the recess 2e of the rotating disk 2, and the rotating disk 2 presses the sliding ring 3 toward the sliding contact surface 1b of the control disk 1 by the compression reaction force. Since the sliding ring 3 is brought into contact with the sliding contact surface 1b and the sliding ring 3 is elastically compressed, the sliding contact surface of the control disk 1 is maintained in a stationary state of the rotating disk 2 where no centrifugal force acts on the steel ball 9. The pressing force (predetermined thrust) for pressing the sliding ring 3 against 1b, and the pressing force of the sliding ring 3 against the sliding contact surface 1b of the control disk 1 is set to a desired value. Adjusting the screwing amount of screw 12 to the shaft 11.

  On the other hand, when the rotating disk 2 rotates around the central axis C and centrifugal force acts on the steel ball 9, the steel ball 9 is centered along the inner surface of the outer peripheral flange 2 c of the rotating disk 2 and the concave surface 1 a of the control disk 1. While moving radially outward with respect to the axis C, the rotary disk 2 is pushed away from the control disk 1 (to the right in FIG. 1) to further compress the highly elastic washer 4 and The amount of compression is reduced, and the pressing force applied to the sliding ring 3 toward the sliding contact surface 1b of the control disk 1, and hence the friction braking force of the sliding ring 3 against the sliding contact surface 1b of the control disk 1 is decreased. Therefore, the steel ball 9, the inner surface of the outer peripheral flange 2 c of the rotating disk 2, and the concave surface 1 a of the control disk 1 constitute a pressing force changing mechanism 5.

  In this embodiment, when the rotating disk 2 is stationary, a slight clearance is provided between the steel ball 9 abutting on the outer peripheral flange 2c on the outer surface side and the concave surface 1a of the control disk 1 as shown in FIG. The axial thickness of the sliding ring 3 under the above-mentioned desired thrust is set so that CL is free. Therefore, the centrifugal force acting on the steel ball 9 with a certain increase in the rotational speed of the rotating disk 2 Until the steel ball 9 continuously contacts the concave surface 1a, the pressing force of the sliding ring 3 on the sliding contact surface 1b of the control disk 1 does not decrease.

  In the rotary damper of this embodiment, the sliding ring 3 fixed to the rotary disk 2 is pressed by the high elastic washer 4 toward the control disk 1 and slides on the sliding contact surface 1b of the control disk 1. Friction braking force is applied to the relative rotation of the rotating disk 2 with respect to the control disk 1 in contact with the steel ball 9, the inner surface of the outer peripheral flange 2 c of the rotating disk 2, and the concave surface 1 a of the control disk 1. Is raised, the pressing force applied to the sliding ring 3 is reduced as described above by the centrifugal force acting on the steel ball 9, and the frictional braking force of the sliding ring 3 is reduced.

  Therefore, according to the rotary damper of this embodiment, when it is provided in a rotary robot joint drive device, vibration is suppressed with a high braking force when the operation speed of the joint is low or when the operation is started, During normal operation, which increases the operating speed, the braking force decreases, the rotational resistance decreases, and the energy loss decreases, so even if it is used for a flexible robot joint with reduced output, normal operation of the robot is hindered. Therefore, it is possible to quickly attenuate the vibration caused by the fluctuation of the driving torque when the operation is stopped, and to shorten the task time of the work. In addition, since the braking force is applied to the joint even when the joint is stopped, the arm of the robot can be maintained at the stop position without providing a separate brake.

  In addition, according to the rotary damper of this embodiment, the pressing force changing means is configured so that the pressing force applied to the sliding ring 3 using the centrifugal force applied to the steel ball 9 turning around the central axis C as the rotating disk 2 rotates. Since the pressure is reduced, the pressing force of the highly elastic washer 4 can be reduced by a mechanical configuration, and the pressing force changing means can be configured at low cost.

  Further, according to the rotary damper of this embodiment, the highly elastic washer 4 applies a pressing force toward the control disk 1 in the direction of the central axis C to the sliding ring 3, and the pressing force changing means includes the steel ball 9, The control disk 1 has a concave conical concave surface 1a that comes into contact with the steel ball 9, and the rotary disk 2 has an outer peripheral flange 2c that comes into contact with the steel ball 9 on the inner surface. The centrifugal force applied to the sphere 9 is converted into a force in the direction of the central axis C by the concave surface 1a, and the rotary disk 1 is pressed in a direction away from the control disk 2 by the axial force, so that the pressing force changing means can be simply and inexpensively. Can be configured.

  FIG. 5 is a characteristic diagram illustrating the relationship between the rotational speed (rotational speed) of the rotary disk 2 of the rotary damper of the above embodiment and the damping torque (friction braking force) between the control disk 1 and the rotary disk 2. In the figure, a curve A shows a case where an intended thrust 35N is applied to the sliding ring 3, and a curve B shows a case where an intended thrust 50N is applied to the sliding ring 3, respectively. In any case, up to about 500 rpm (rotation / min), the damping torque does not change because the centrifugal force of the steel ball 9 is small, and when it exceeds about 500 rpm, in the curve A, the damping torque is increased to about 2000 rpm. When it decreases from about 40 mNm to about 5 mNm and exceeds about 2000 rpm, the sliding ring 3 is separated from the sliding contact surface 1b of the control disk 1 and the damping torque becomes substantially zero although it is not apparent in the figure. In curve B, the damping torque decreases from about 56 mNm to about 2 mNm while increasing to about 2500 rpm, and when it exceeds about 2500 rpm, the sliding ring 3 moves away from the sliding contact surface 1b of the control disk 1 although it is not apparent in the figure. As a result, the damping torque becomes substantially zero.

  Therefore, also from this figure, when the rotary damper of the above embodiment is provided in the robot joint drive device of the rotary system, vibration is suppressed with a high braking force when the operation speed of the joint is low or when the operation is started, It is clear that during normal operation when the operating speed of the engine increases, the braking force decreases, the rotational resistance decreases, and the energy loss decreases. If the sliding ring 3 is made of a synthetic rubber and has a large amount of elastic deformation in the axial direction as described above, a damping torque (friction braking force) over a wide range of changes in the rotational speed of the rotating disk 2 is achieved. However, if the sliding ring 3 is made of a carbon ring or the like with little or no elastic deformation, the damping torque can be reduced to substantially zero with a slight change in the rotational speed of the rotating disk 2. It can be reduced rapidly. Moreover, if the number of steel balls 9 to be used is decreased, the inclination of the decrease in the damping torque with respect to the increase in the rotational speed can be reduced.

  6 (a), 6 (b) and 6 (c) exemplify a working robot equipped with a shoulder joint drive device as an embodiment of the robot joint drive device of the present invention equipped with the rotary damper of the above embodiment. Front view, side view and perspective view, FIGS. 7A, 7B and 7C are a side view, a front view and a perspective view of the entire arm showing the configuration of the shoulder joint drive device of the above embodiment, and FIG. 8 is a cross-sectional view taken along the line DD in FIG. 7A showing the configuration of the shoulder joint drive device of the above embodiment. In the figure, reference numeral 20 denotes the work robot, and 30 denotes the rotation of the embodiment. Shows the damper.

  The work robot 20 is for coexisting and cooperating with a person at a cell production site or the like, and as shown in FIG. 6, a body 21 having a box-shaped upper part 21a and a columnar lower part 21b, A head 22 provided at the upper end of the upper portion 21 a of the body 21, two arms 23 provided on the left and right sides when viewed from the robot itself of the upper portion 21 a of the body 21, and provided at the tips of these arms 23. A hand (not shown) as an example of the end effector and a cart (not shown) for supporting the lower portion 21b of the body 21 instead of the legs are provided.

  The work robot 20 has two video cameras 24 as imaging means mounted on the head 22 and a neck joint 25 between the upper part 21 a of the body 21 and the head 22, and the neck joint 25. Has a neck joint drive device composed of a neck pitch shaft drive device that tilts the head 22 back and forth about the axis P1 and a neck yaw shaft drive device that rotates the head 22 left and right around the axis Y1. In addition, the working arm robot 20 includes a waist joint 26 between an upper portion 21a and a lower portion 21b of the body 21, and the waist joint 26 is an axis line with respect to the upper portion 21a of the body 21 and the lower carriage 21b. A hip joint drive device including a waist yaw axis drive device that rotates left and right around Y1 is provided.

  Further, as shown in FIG. 7 as well, the work robot 20 includes a shoulder joint 27 between the trunk 21 and the upper arm 23a of each arm 23, and between the upper arm 23a and the lower arm 23b of each arm 23. An elbow joint 28, a lower arm 23 b of each arm 23, and a wrist joint 29 between the above hands are provided, and each shoulder joint 27 protrudes to the left and right of the body 21 to form a substantially bracketed shoulder bracket 31. A shoulder yaw axis driving device 27a that is arranged on the upper side and pivots the entire arm 23 to the left and right relatively around the axis Y2 with respect to the body 21, and an axis P2 orthogonal to the axis Y2 of the shoulder yaw axis driving device 27a The shoulder joint drive device according to the above-described embodiment, which includes a shoulder pitch axis drive device 27b that tilts the entire arm 23 back and forth relative to the body 21, is provided. In the figure, the shoulder pitch shaft drive device 27b on the left shoulder is shown with the belt-type transmission mechanism cover removed.

  Here, since the upper surface of the shoulder bracket 31 is inclined obliquely downward with respect to the axis Y1, each axis Y2 is inclined with respect to the vertical direction of the trunk 21 and becomes closer to the trunk 21 as it goes downward. Along with this, the axis P2 perpendicular to the axis Y2 is also inclined with respect to the floor surface. The upper arm 23a of the arm 23 extends so as to be closer to the body 21 as the portion closer to the elbow joint 28 is lowered. Thus, each arm 23 is restricted from swinging to the side of the body 21 in the front-facing state shown in FIG. 6, so that even if a person is lined up next to the work robot 20, Since there is little possibility of interference, the work robot 20 can work safely with coexistence and cooperation with people.

  Furthermore, each elbow joint 28 has an elbow joint drive device including an elbow pitch axis drive device that tilts the lower arm 23b up and down around an axis P3 parallel to the axis P2 with respect to the upper arm 23a, and each wrist joint 29 Is a wrist pitch driving device that tilts the hand relatively up and down around the axis P4 with respect to the lower arm 23b, and a wrist yaw that rotates the hand relatively left and right around the axis Y3 orthogonal to the axis P4. The wrist joint driving device includes a shaft driving device and a wrist roll shaft driving device that twists the wrist pitch shaft driving device and the wrist yaw shaft driving device around the axis R with respect to the lower arm 23b. As a result, each arm 23 has a total of six movable shaft driving devices and thus six degrees of freedom, and the two arms 23 have a singularity and have a free posture by the axial arrangement of these movable shaft driving devices. Can do.

  In addition, the work robot 20 is equipped with a control device (not shown) having a normal computer in the cart, whereby the work robot 20 is self-propelled by the cart or moved manually by the work place. , Based on images from the two video cameras 24 of the head 22, for example, the type of the work object is recognized by image processing and the position of the work object is recognized by camera surveying according to a program given in advance. In addition, since the work on the work object is performed, work such as assembly and inspection can be automatically performed in cooperation with a person and in cooperation.

  Here, each of the above-described movable shaft driving devices for the joints 25 to 29 is, as is well known, a rotation mechanism that decelerates and outputs the output rotation of a motor such as a servo motor with a speed reducer such as a brand name harmonic drive. For example, the shoulder yaw axis driving device 27a in the shoulder joint driving device of the above embodiment includes a substantially cylindrical casing 32 having an outer peripheral flange 32a fixed to the upper surface of the shoulder bracket 31, and the axial direction of the casing 32. A servo motor 33 attached to one end (the lower end in FIG. 8), a harmonic drive 34 accommodated in the casing 32, and an axis line via a bearing on the other end (the upper end in FIG. 8) of the casing 32. A base member 35 that is rotatably supported around Y2 and supports the shoulder pitch shaft drive device 27b at one axial end (upper end in FIG. 8). And have.

  The harmonic drive 34 has an internal gear 34a fixed to the casing 32 and an external gear that can be elastically deformed in the radial direction at one end in the axial direction (lower end in FIG. 8). A substantially cup-shaped flexspline 34b formed with a number and having the other end (upper end in FIG. 8) coupled to the other end (lower end in FIG. 8) of the base member 35, and elastically deformable in the radial direction A drive disk 34c that pushes and spreads the external gear of the flex spline 34b in the circumferential direction partially radially outward through a simple bearing and partially meshes the external gear with the internal gear 34a in the circumferential direction. The servo motor 33 has its output shaft 33a coupled to the drive disk 34c to rotate the drive disk 34c, so that the drive disk 34c is located outside the flex spline 34b. The meshing position of the toothed gear and the internal gear 34a is moved in the circumferential direction, and the internal gear 34a and then the flex spline 34b and then the base member 35 with respect to the casing 32, and the output shaft 33a of the servomotor 33 and the rotation of the drive disk 34c. Is rotated around the axis Y2 with a large reduction ratio corresponding to the number of teeth of the external gear and the internal gear 34a of the flexspline 34b with respect to the number, and the entire arm 23 is relatively moved around the axis Y2 with respect to the body 21. Turn left and right.

  Further, the shoulder pitch axis driving device 27b in the shoulder joint driving device of the above embodiment includes a substantially cylindrical casing 36 whose side surface is fixed to the upper end portion of the base member 35, and one axial end portion of the casing 36 (FIG. 8). The left end) and a plate-like bracket 37 formed by bending a cover mounting flange 37a (not shown), a servo motor 38 supported by the bracket 37, and a harmonic housed in the casing 36. The drive 39, a belt-type transmission mechanism 40 that drives and connects the servo motor 38 and the harmonic drive 39, and the other end (right end in FIG. 8) of the casing 32 can be rotated around the axis P2 via a bearing. A substantially cylindrical support member 41 that is supported and supports the upper arm 23a of the arm 23 at one end in the axial direction (right end in FIG. 8); Here, the rotary damper 30 according to the above-described embodiment is provided between the body 21 and the arm 23 as two link members of the work robot 20.

  The belt-type transmission mechanism 40 includes a toothed pulley 42 coupled to the output shaft 38a of the servo motor 38, the above-described toothed pulley 7 provided in the rotary damper 30, and the toothed pulleys 42, 7 between them. The rotation of the output shaft 38a of the servo motor 38 from the toothed pulley 42 through the toothed belt 43 to the toothed pulley 7 and the toothed pulley 42 and the toothed pulley 7 It transmits with the reduction ratio according to the number of teeth.

  The harmonic drive 39 includes an internal gear 39a fixed to the casing 36, and an external gear that is elastically deformable in the radial direction at one end in the axial direction (left end in FIG. 8). The number of teeth is slightly smaller than that of the internal gear 39a. And a substantially cup-shaped flexspline 39b in which the other end (the right end in FIG. 8) is coupled to the other end (the left end in FIG. 8) of the support member 41, and is elastically deformable in the radial direction. A drive disk 39c for enlarging the external gear of the flex spline 39b in the circumferential direction partially radially outward via the bearing and partially engaging the external gear with the internal gear 39a in the circumferential direction; and a casing The one end of 36 is rotatably supported around the axis P2 via a bearing, and one end in the axial direction (right end in FIG. 8) is coupled to the drive disk 39c and the other end (in FIG. 8). The left end) has an input shaft 39d coupled to the toothed pulley 7, and the servo motor 38 is coupled to the drive disk 39c via the belt-type transmission mechanism 40 and the input shaft 39d. Then, the drive disk 39c is rotated, whereby the drive disk 39c is moved flexibly with respect to the internal gear 39a and thus the casing 36 by moving the meshing position of the external gear and the internal gear 39a of the flex spline 39b in the circumferential direction. The spline 39b and the support member 35 are rotated around the axis P2 with a large reduction ratio according to the number of teeth of the external gear and the internal gear 39a of the flexspline 39b with respect to the rotational speed of the output shaft 38a of the servo motor 38 and the drive disk 39c. The entire arm 23 is tilted back and forth relative to the body 21 about the axis P2.

  In the rotary damper 30 of the above embodiment, the toothed pulley 7 fixed to the outer surface of the rotary disk 2 is coupled to the input shaft 39d of the harmonic drive 39 as described above, and the cover 6 has an outer peripheral surface. The distal end portions of the fixing pins 44 are screwed into the fixing holes 6a (see FIGS. 2 and 4) formed in a plurality of protrusions provided at intervals in the circumferential direction, and the base end portions of the fixing pins 44 are bracketed. 37, the cover 6 is coupled to the casing 36 by screws (not shown), whereby the cover 6 is coupled to the shoulder bracket 31 and thus the body 21 via the casing 36 and the shoulder yaw axis driving device 27a. .

  In the shoulder joint driving device of this embodiment, the input shaft 39d is provided on the shoulder pitch axis driving device 27b of the shoulder joint 27 that connects the body 21 and the arm 23 as two link members of the work robot 20. Is connected to the output shaft 38a of the servo motor 38, and the input shaft 39d of the harmonic drive 39 for tilting the arm 23 with respect to the body 21 by the output rotation obtained by reducing the rotation of the output shaft 38a, and the two link members When the rotational speed of the input shaft 39d of the harmonic drive 39 increases, the rotary damper 30 of the above embodiment provided between the body 21 as one side reduces the braking force applied to the body 21 to the input shaft 39d.

  Therefore, according to the shoulder joint drive device of this embodiment, when the operation speed of the shoulder pitch shaft drive device 27b of the shoulder joint 27 is low or at the start of operation, the vibration of the arm 23 is suppressed with a high braking force and the operation speed is reduced. Since the braking force decreases during the normal operation that rises, and the rotational resistance decreases and energy loss decreases, the flexible work robot 20 with a small output can be operated or stopped without disturbing the normal operation. The vibration of the arm 23 due to the fluctuation of the driving torque at the start can be quickly attenuated, and the task time of the work can be shortened. In addition, since the braking force is applied to the shoulder joint 27 even while the operation of the shoulder pitch axis driving device 27b of the shoulder joint 27 is stopped, the arm 23 can be maintained at the stopped position in a state where the arm 23 is lifted without providing a separate brake.

  Although the present invention has been described based on the illustrated examples, the present invention is not limited to the above-described embodiments, and can be appropriately changed within the scope of the claims, for example, rotation of the present invention. In the damper, the friction member may be fixed to the base member side, pressed against the rotating member and slidably contacted with the rotating member, and a friction braking force may be applied to the relative rotation of the rotating member with respect to the base member. Also, the friction member is provided on one of the base member and the rotating member that are aligned in the radial direction, and the pressing means applies a pressing force toward the radially inward portion of the portion positioned radially outward. In addition, the friction member is slidably brought into contact with the other portion, and the pressing force changing means acts on the portion located radially outward when the rotational speed of the rotating member increases, and the pressing force applied to the friction member can be reduced. good.

  In the robot joint drive device according to the present invention, the rotation damper may be provided between the output shaft of the motor and the link member, and the joint connecting the two link members of the robot provided with the rotation damper is a shoulder. Similarly to the pitch axis drive device 27b, an elbow joint or a wrist joint to which a load is applied during operation stop may be used.

  Thus, according to the rotary damper of the present invention, when provided in a rotary system robot joint drive device, vibration is suppressed with a high braking force at the time of operation stop or operation start when the joint operation speed is low, while the joint operation speed is During normal operation, the braking force is reduced, and the rotational resistance is reduced and energy loss is reduced, so even if it is used for a flexible robot joint with reduced output, it does not interfere with the normal operation of the robot. It is possible to quickly attenuate the vibration due to the fluctuation of the driving torque when the operation is stopped, and to shorten the task time of the work. In addition, since the braking force is applied to the joint even when the joint is stopped, the arm of the robot can be maintained at the stop position without providing a separate brake.

  Further, according to the robot joint driving device of the present invention, during a normal operation in which the operation speed of the joint that connects the two link members of the robot is low, when the operation is stopped or when the operation is started, the vibration is suppressed with a high braking force and the operation speed is increased. Since the braking force is reduced and the rotational resistance is reduced, energy loss is reduced, even when used in a flexible robot joint with reduced output, normal operation of the robot is not interrupted or started without interruption. It is possible to quickly attenuate the vibration due to the fluctuation of the driving torque at the time and to shorten the task time of the work. In addition, since the braking force is applied to the joint even when the joint is stopped, the arm of the robot can be maintained at the stop position without providing a separate brake.

DESCRIPTION OF SYMBOLS 1 Control disk 1a Concave surface 1b Sliding contact surface 1c Through hole 2 Rotating disk 2a Annular groove 2b, 2c Outer peripheral flange 2d Ball receiving groove 2e Recess 2f Through hole 3 Sliding ring (friction member)
4 High elastic washer (pressing means)
5 Pressing force changing mechanism (Pressing force changing means)
6 Cover 6a Fixing hole 7, 42 Toothed pulley 8 Bolt 9 Steel ball 10 Bearing 10a Outer race 10b Inner race 11 Press shaft 11a Outer flange 11b Female screw 12 Positioning screw 13 Holding washer 20 Work robot 21 Body 21a Upper part 21b Lower part 22 Head 23 arm 23a upper arm 23b lower arm 24 video camera 25 neck joint 26 waist joint 27 shoulder joint 27a shoulder yaw axis drive device (joint drive device)
27b Shoulder pitch axis drive (joint drive)
28 Elbow joint 29 Wrist joint 30 Rotation damper 31 Shoulder bracket 32, 36 Casing 32a Outer flange 33, 38 Servo motor 33a, 38a Output shaft 34, 39 Harmonic drive 34a, 39a Internal gear 34b, 39b Flex spline 34c, 39c Drive disk 35 Base member 37 Bracket 37a Flange 39d Input shaft 40 Belt type transmission mechanism 41 Support member 43 Toothed belt 44 Fixed pin C Center axis CL Clearance P1, P2, P3, P4 Axis R Axis Y1, Y2, Y3 Axis

Claims (4)

A base member;
A rotating member arranged to be rotatable around a predetermined axis with respect to the base member;
A friction member fixed to at least one of the base member and the rotation member and pressed toward the other to be in sliding contact with the other, and applying a friction braking force to the relative rotation of the rotation member with respect to the base member;
A pressing means for applying a pressing force to the friction member toward the other;
A pressing force changing means for reducing the pressing force applied to the friction member when the rotational speed of the rotating member increases;
Rotating damper with   2. The rotary damper according to claim 1, wherein the pressing force changing unit reduces the pressing force by using a centrifugal force applied to a weight member rotating around the axis along with the rotation of the rotating member. The pressing means applies a pressing force to the friction member toward the other side in the axial direction,
The pressing force changing means is
A steel ball as the weight member;
A disc-like member as the base member having a conical concave surface centered on the axis and in contact with the steel ball;
Have
The disk-shaped member converts a centrifugal force applied to the steel ball into the axial force on the concave surface, and presses the rotating member in a direction away from the disk-shaped member with the axial force. The rotary damper according to claim 2. A drive device provided at a joint connecting two link members of a robot,
A motor,
A reduction gear coupled to the output shaft of the motor for driving the input shaft and rotating one of the two link members with respect to the other by an output rotation obtained by reducing the rotation of the output shaft of the motor;
4. The device according to claim 1, wherein the motor is provided between an output shaft of the motor or an input shaft of the speed reducer and one of the two link members, and brakes the rotation of the shaft with respect to the one link member. 5. The rotary damper according to 1;
Robot joint drive device comprising

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