CN110614650A - Manipulator and flexible meshing type gear device - Google Patents

Abstract

The invention provides a manipulator capable of prolonging the service life of a main bearing of a speed reducer arranged at a joint part and a flexible meshing type gear device suitable for the manipulator. The manipulator is provided with: a1 st arm member (13), a2 nd arm member (17), and a drive means (19) for driving the 2 nd arm member (17) with respect to the 1 st arm member (13). The drive device (19) comprises: the drive device comprises a fixed member (51) fixed to the 1 st arm member (13), a speed reduction mechanism (50), an output member (52) to which rotation reduced by the speed reduction mechanism (50) is transmitted and which is connected to the 2 nd arm member (17), and a main bearing (59) disposed between the fixed member (51) and the output member (52). When viewed in the radial direction of the main bearing (59), the center of gravity (G17) of the 2 nd arm member (17) overlaps the range (W1) of the rolling surface of the rolling element of the main bearing.

Description

Manipulator and flexible meshing type gear device

The present application claims priority based on japanese patent application No. 2018-115057, applied on 6/18/2018. The entire contents of this Japanese application are incorporated by reference into this specification.

Technical Field

The present invention relates to a manipulator and a flexible meshing gear device.

Background

An industrial robot includes an arm and a joint portion for rotating the arm, and the joint portion is provided with a speed reducer for reducing a rotational motion generated by a motor or the like and transmitting the reduced rotational motion to the arm (see, for example, patent document 1). The speed reducer 31 provided in the joint portion of patent document 1 includes: a housing 31b fixed to the frame, an input gear 31a for inputting a rotational motion, and an output shaft 31c connected to the arm 4.

As shown in fig. 2 and 4 of patent document 1, the arm 4 of the industrial robot is often coupled to the outside of the output shaft 31c of the speed reducer 31 in the axial direction and arranged to extend from the coupling portion in the rotational radial direction.

Patent document 1: japanese patent laid-open No. 2014-69269

The speed reducer is provided with: the power transmission device includes a fixed member coupled to a base member, an output member coupled to a target of output of power (i.e., a target member), and a main bearing disposed between the fixed member and the output member. The output member is rotatably supported by the fixed member via a main bearing.

In the case where the arm is connected to the axially outer side of the output member of the reduction gear and is disposed so as to extend from there in the rotational radial direction, as in the above-described conventional industrial robot, the arm when a load is applied from the arm in the longitudinal direction thereof becomes long with the main bearing as a fulcrum. The moment arm represents the distance between the fulcrum and the line of action of the force. Since the product of the load and the moment arm becomes a moment applied to the fulcrum, if the moment arm of the reduction gear is increased, the moment applied to the main bearing is increased even if the load is small. Therefore, in the conventional industrial robot in which the speed reducer having a long moment arm is provided in the joint portion, a large moment is easily applied to the main bearing of the speed reducer, and the life of the main bearing is shortened.

Disclosure of Invention

The invention aims to provide a manipulator capable of prolonging the service life of a main bearing of a speed reducer arranged at a joint part and a flexible meshing type speed reducer suitable for the manipulator.

The manipulator according to the present invention includes a1 st arm member, a2 nd arm member, and a driving device for driving the 2 nd arm member with respect to the 1 st arm member,

the drive device includes: a fixed member fixed to the 1 st arm member, a speed reduction mechanism, an output member to which rotation reduced by the speed reduction mechanism is transmitted and which is connected to the 2 nd arm member, and a main bearing disposed between the fixed member and the output member,

when viewed in a radial direction of the main bearing, a center of gravity of the 2 nd arm member overlaps with a range of rolling surfaces of rolling elements of the main bearing.

The present invention relates to a flexible meshing gear device including: a vibration generator, an external gear which is deformed by the vibration generator, a1 st internal gear and a2 nd internal gear which mesh with the external gear, and a main bearing which is arranged between the 1 st internal gear and the 2 nd internal gear,

the 1 st internal gear is rotatable integrally with an outer ring of the main bearing, the 2 nd internal gear is rotatable integrally with an inner ring of the main bearing,

the 2 nd internal gear has an extended portion that extends to a radially outer side of an outer ring member that constitutes an outer ring of the main bearing.

According to the present invention, the effect of improving the life of the main bearing of the speed reducing mechanism provided at the joint portion between the 1 st arm member and the 2 nd arm member can be obtained.

Drawings

Fig. 1 is a side view showing a robot hand according to an embodiment of the present invention.

Fig. 2 is a rear view of the robot hand of fig. 1 as viewed from the 2 nd arm rotation direction.

Fig. 3 is a sectional view showing the 2 nd arm and the 2 nd driving device.

Fig. 4 is a cross-sectional view showing a joint portion of a comparative example.

In the figure: 1-robot, 13-first slewing arm, 17-second arm, 19-second drive device, 50-reduction gear, 51-fixed part, 51G-first internal gear, 52-output part, 52 ex-extension part, 52G-second internal gear, 53-input shaft, 55-external gear, 56-oscillator bearing, 58A, 58B-input bearing, 59-main bearing, 61-motor, 61 a-motor shaft, 61B-connection part, C1, C2-connection part, 171-first frame part, 172-second frame part, G17-center of gravity of second arm, W1-range of rolling surface.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a side view showing a robot hand according to an embodiment of the present invention. Fig. 2 is a rear view of the robot hand of fig. 1 as viewed from the 2 nd arm rotation direction.

The robot 1 according to the embodiment of the present invention is an industrial robot or a cooperative robot that cooperates with a human, and specifically, is an articulated robot. The manipulator 1 includes: the machining head 41 includes a base member 11, a1 st swing arm 13, a1 st drive device 15, a2 nd arm 17, a2 nd drive device 19, a3 rd arm 21, a3 rd drive device 23, a4 th swing arm 25, a4 th drive device 27, a5 th arm 29, a5 th drive device 31, a6 th arm 33, a6 th drive device 35, and a head drive device 43. The 1 st swivel arm 13 corresponds to an example of the 1 st arm member according to the present invention. The 2 nd arm 17 corresponds to an example of the 2 nd arm member according to the present invention. The 2 nd driving device 19 corresponds to an example of the driving device according to the present invention.

The base member 11 is fixed to the working space and serves as a base of the robot 1. The 1 st swing arm 13 is supported by the base member 11 via a1 st drive device 15 so as to be swingable with respect to the base member 11. The 2 nd arm 17 is supported by the 1 st swing arm 13 via a2 nd drive device 19 so as to be rotatable with respect to the 1 st swing arm 13. The 3 rd arm 21 is supported by the 2 nd arm 17 via a3 rd driving device 23 so as to be rotatable with respect to the 2 nd arm 17. The 4 th swing arm 25 is supported by the 3 rd arm 21 via a4 th drive device 27 so as to be swingable with respect to the 3 rd arm 21. The 5 th arm 29 is supported by the 4 th swing arm 25 via a5 th drive device 31 so as to be rotatable with respect to the 4 th swing arm 25. The 6 th arm 33 is supported by the 5 th arm 29 via a6 th drive device 35 so as to be rotatable with respect to the 5 th arm 29. Focusing on the 2 nd arm 17, one end portion in the longitudinal direction of the 2 nd arm 17 is rotatably supported by the 1 st swing arm 13 via the 2 nd drive device 19, and the other end portion in the longitudinal direction of the 2 nd arm 17 rotatably supports the 3 rd arm 21 via the 3 rd drive device 23.

The 1 st to 6 th driving devices 15, 19, 23, 27, 31 and 35 function as the 1 st to 6 th joint portions between the arms, respectively.

The 1 st driving device 15 includes: a fixed member connected to the base member 11, an output member supported rotatably about a rotation axis a1 on the fixed member, a motor generating power, and a speed reduction mechanism for reducing the speed of the rotation of the motor and transmitting the reduced speed to the output member. The 1 st swing arm 13 is connected to an output member of the 1 st driving device 15, and swings around a swing axis a1 by driving of the 1 st driving device 15.

The 2 nd driving device 19 includes: the fixed member 51 (fig. 3) coupled to the 1 st swing arm 13, and the output member 52 (fig. 3) rotatably supported by the fixed member 51 about a rotation axis a 2. The 2 nd driving device 19 further includes: a motor 61 for generating power, and a reduction mechanism 50 for reducing the speed of the rotation of the motor 61 and transmitting the reduced speed to the output member 52. The 2 nd arm 17 is coupled to the output member 52 of the 2 nd driving device 19, and is rotated about the rotation axis a2 by the driving of the 2 nd driving device 19.

The 3 rd driving device 23 includes: a fixed member coupled to the 2 nd arm 17, an output member rotatably supported by the fixed member about a rotation axis a3, a motor generating power, and a speed reduction mechanism reducing the speed of the rotation of the motor and transmitting the reduced speed to the output member. The 3 rd arm 21 is coupled to an output member of the 3 rd driving device 23, and is rotated about a rotation axis a3 by driving of the 3 rd driving device 23.

The 4 th driving device 27 includes: a fixed member coupled to the 3 rd arm 21, an output member supported rotatably about a rotation axis a4 on the fixed member, a motor generating power, and a speed reduction mechanism for reducing the speed of the rotation of the motor and transmitting the reduced speed to the output member. The 4 th swing arm 25 is connected to an output member of the 4 th driving device 27, and swings around a swing axis a4 by driving of the 4 th driving device 27.

The 5 th driving device 31 includes: a fixed member coupled to the 4 th swing arm 25, an output member supported rotatably about a rotation axis a5 on the fixed member, a motor generating power, and a speed reduction mechanism for reducing the speed of the rotation of the motor and transmitting the reduced speed to the output member. The 5 th arm 29 is coupled to an output member of the 5 th driving device 31, and is rotated about a rotation axis a5 by driving of the 5 th driving device 31.

The 6 th driving device 35 has: a fixed member coupled to the 5 th arm 29, an output member rotatably supported by the fixed member about a rotation axis a6, a motor generating power, and a speed reduction mechanism for reducing the speed of the rotation of the motor and transmitting the reduced speed to the output member. The 6 th arm 33 is coupled to an output member of the 6 th driving device 35, and is rotated about a rotation axis a6 by driving of the 6 th driving device 35.

The driving devices on the machining head 41 side, such as the 5 th driving device 31 and the 6 th driving device 35, may be configured such that power is transmitted from a motor provided at a position distant from the driving unit. Further, the driving devices on the machining head 41 side, such as the 5 th driving device 31 and the 6 th driving device 35, may be configured to transmit only the motion without amplifying the torque by omitting the speed reduction mechanism.

In the 1 st to 6 th driving devices 15, 19, 23, 27, 31, and 35, a bearing (hereinafter, referred to as a "main bearing") is provided between a fixed member and an output member, and the output member is rotatably or revolvably supported by the fixed member via the main bearing.

The machining head 41 is held at the distal end portion of the 6 th arm 33, and performs a machining process such as welding on the object to be machined.

The head driving device 43 is held by the 3 rd arm 21, and supplies energy such as laser light or electric power to the machining head 41.

With the above configuration, the robot 1 can rotate the 1 st and 4 th swing arms 13 and 25 and rotate the 2 nd, 3 rd, 5 th, and 6 th arms 17, 21, 29, and 33, and can move the machining head 41 in the three-axis direction and change the angle of the machining head 41. Thus, the robot 1 can move the machining head 41 with a high degree of freedom, and can perform machining on various positions of the object from various angles.

< 2 nd drive device >

Fig. 3 is a sectional view showing the 2 nd arm and the 2 nd driving device. In the present specification, unless otherwise specified, the axial direction indicates a direction along the rotation axis O1 of the 2 nd drive device 19, and the radial direction indicates a direction perpendicular to the rotation axis O1.

As described above, the 2 nd driving device 19 includes: reduction mechanism 50, fixed member 51, output member 52, main bearing 59, and motor 61. Here, a configuration in which the reduction mechanism 50, the fixed member 51, the output member 52, and the main bearing 59 are combined corresponds to an example of the flexible mesh gear device according to the present invention.

The speed reduction mechanism 50 includes: an input shaft 53 having a vibration generating body 53a, an external gear 55 which is bent and deformed by the vibration generating body 53a, and a1 st internal gear 51g and a2 nd internal gear 52g which mesh with the external gear 55. Further, the reduction mechanism 50 further includes: an input bearing 58A and an input bearing 58B for supporting the input shaft 53, and a vibration generator bearing 56 disposed between the external gear 55 and the vibration generator 53 a.

The fixing member 51 is constituted by connecting: a1 st member 51A having a1 st internal gear 51g, a2 nd member 51B having an input bearing 58A embedded therein, and a3 rd member 51C having a main bearing 59 embedded therein are provided. Since a part of the 3 rd member 51C functions as an outer ring of the main bearing 59, the fixed member 51 can rotate integrally with the outer ring of the main bearing 59. The fixed member 51 corresponds to an example of the outer ring member according to the present invention.

The fixing member 51 may be formed by integrally forming the 1 st member 51A, the 2 nd member 51B, and the 3 rd member 51C as one member, or may be divided into a plurality of members at other portions and coupled together via a coupling member. Since the fixed member 51 and the 1 st internal gear 51g are integrated, the fixed member 51 itself may be referred to as the 1 st internal gear.

The output member 52 is constituted by connecting: a1 st member 52A having a2 nd internal gear 52g and a main bearing 59 fitted externally thereon, and a2 nd member 52B having an input bearing 58B fitted therein are provided. Since a part of the 1 st member 52A functions as an inner ring of the main bearing 59, the output member 52 can rotate integrally with the inner ring of the main bearing 59. The 2 nd member 52B has an extended portion 52ex that extends from the outer peripheral side of the input bearing 58B to the radially outer side of the fixed member 51 through the side of the fixed member 51 opposite to the motor side. The extending portion 52ex extends to the motor side of the main bearing 59 in the axial direction. The motor side indicates a side on which the motor 61 is arranged in the axial direction, and the side opposite to the motor side indicates the opposite side. The 2 nd member 52B is configured not to protrude further outward in the axial direction than the input bearing 58B when the side on which the main bearing 59 is disposed is the axial direction inner side. In other words, the end portion of the output member 52 on the side opposite to the motor side is located at the same position as the end portion of the input bearing 58B on the side opposite to the motor side or located more inward in the axial direction than the end portion of the input bearing 58B on the side opposite to the motor side in the axial direction of the reduction mechanism 50.

The output member 52 may be configured such that the 1 st member 52A and the 2 nd member 52B are integrally formed by one member, or may be configured such that they are divided into a plurality of members at other portions and connected together via a connecting member. Since the output member 52 and the 2 nd internal gear 52g are integrated, the output member 52 itself may be referred to as the 2 nd internal gear.

The input shaft 53 is hollow and has: the oscillator 53a has an elliptical cross section perpendicular to the rotation axis O1 (not necessarily a geometrically perfect ellipse), and the shaft portions 53b and 53c have circular cross sections perpendicular to the rotation axis O1 and are provided on both sides of the oscillator 53a in the axial direction. A motor shaft 61a of the motor 61 is coupled to one end of the input shaft 53 via a coupling member 61b, and thus, a driving force is input from the motor 61. The input shaft 53 is rotated about the rotation shaft O1 by the power of the motor 61.

The external gear 55 is a flexible cylindrical metal, and has teeth on its outer periphery. The external gear 55 is held by the oscillator 53a via the oscillator bearing 56 and is rotatable with respect to the oscillator 53 a.

One of the 1 st internal gear 51g and the 2 nd internal gear 52g meshes with the teeth of the external gear 55 on one side of the center in the axial direction, and the other meshes with the teeth of the external gear 55 on the other side of the center in the axial direction. The 1 st internal gear 51g is formed by forming teeth at corresponding positions on the inner peripheral portion of the 1 st member 51A of the fixed member 51. The 2 nd internal gear 52g is formed by forming teeth at corresponding positions on the inner peripheral portion of the 1 st member 52A of the output member 52.

The input bearings 58A and 58B are sealed bearings provided with a lubricant seal member. Therefore, no separate oil seal is provided between the input shaft 53 and the fixed member 51 and the output member 52, and the axial dimension of the device can be reduced. The input bearing 58A is disposed between the 2 nd member 51B of the fixed member 51 and the one-side (motor-side) shaft portion 53B of the input shaft 53. The input bearing 58B is disposed between the 2 nd member 52B of the output member 52 and the shaft portion 53c on the other side (opposite to the motor side) of the input shaft 53. The input shaft 53 is rotatably supported by the fixed member 51 and the output member 52 via input bearings 58A and 58B.

The main bearing 59 is, for example, a cross roller bearing capable of bearing both axial loads and radial loads. The rolling elements of the main bearing 59 include a plurality of 1 st rollers and a plurality of 2 nd rollers, and the plurality of 2 nd rollers are arranged in a direction in which the rotation axes thereof intersect with the rotation axis of the 1 st roller. The main bearing 59 is disposed between the inner peripheral side of the 3 rd member 51C of the fixed member 51 and the outer peripheral side of the 1 st member 52A of the output member 52. The output member 52 is supported by the fixed member 51 via the main bearing 59 so as to be relatively rotatable. As described above, in the present embodiment, a part of the fixed member 51 functions as the outer ring of the main bearing 59, and a part of the output member 52 functions as the inner ring of the main bearing 59. However, the main bearing 59 may have a dedicated outer ring and an inner ring, and the outer ring may be fitted to the fixed member 51 so as to be rotatable integrally with the fixed member 51. Alternatively, the inner ring may be fitted to the output member 52 so as to be rotatable integrally with the output member 52.

In the 2 nd driving device 19 configured as described above, the oscillator 53a of the input shaft 53 is rotated by driving the motor 61. When the oscillator 53a rotates, the motion is transmitted to the external gear 55. At this time, the external gear 55 is restricted to a shape conforming to the outer peripheral surface of the oscillator 53a, and is flexed into an elliptical shape when viewed from the axial direction. Further, the portion of the external gear 55 at the position of the elliptical long axis as viewed in the axial direction meshes with the 1 st internal gear 51g and the 2 nd internal gear 52 g. Therefore, the external gear 55 does not rotate at the same rotational speed as the oscillator 53a, and the oscillator 53a rotates relatively inside the external gear 55. With this relative rotation, the external gear 55 is deformed in a manner such that the elliptical long axis position and the elliptical short axis position move in the circumferential direction when viewed from the axial direction. The period of the deformation is proportional to the rotation period of the oscillator 53 a.

The long axis position of the external gear 55 moves when it is deformed, and thereby the meshing position between the external gear 55 and the 1 st internal gear 51g changes in the rotational direction. Here, the number of teeth of the external gear 55 is 100, and the number of teeth of the 1 st internal gear 51g is 102. Based on the difference in the number of teeth, the meshing teeth between the external gear 55 and the 1 st internal gear 51g are shifted every one rotation of the meshing position of the teeth, and the external gear 55 rotates (rotates). If the number of teeth is set as described above, the rotational motion of the input shaft 53 is reduced in speed by a reduction ratio of 100:2 and then transmitted to the external gear 55.

On the other hand, by the rotation of the oscillator 53a, the meshing position between the external gear 55 and the 2 nd internal gear 52g also changes in the rotational direction. Here, the number of teeth of the external gear 55 is the same as that of the 2 nd internal gear 52 g. At this time, the external gear 55 and the 2 nd internal gear 52g do not rotate relatively, and the rotational motion of the external gear 55 is transmitted to the 2 nd internal gear 52g at a reduction ratio of 1: 1. By these operations, the rotational motion of the input shaft 53 is reduced in speed at a reduction ratio of 100:2 and transmitted to the 2 nd internal gear 52g, and the rotational motion is output to the output member 52.

< connection of No. 1 rotating arm, No. 2 driving device and No. 2 arm >

As shown in fig. 3, the 1 st pivoting arm 13 is coupled to the fixed member 51 via a coupling member C1 such as a bolt. Only one connection is shown in the cross section of fig. 3, but it is joined in the same manner at a plurality of points in the circumferential direction. The 1 st rotating arm 13 is disposed on the motor side of the reduction mechanism 50, and is connected to the fixed member 51 from the motor side. The 1 st swivel arm 13 is provided with a through hole h1 along the extending direction of the motor shaft 61 a. The housing 61d of the motor 61 is fixed to the 1 st swing arm 13 on the side opposite to the speed reduction mechanism 50, and the motor shaft 61a is coupled to the input shaft 53 through the through hole h 1.

The 2 nd arm 17 has, at one end side in the longitudinal direction: a hollow portion 173 in which the speed reduction mechanism 50 is disposed, a1 st frame member 171 disposed on the motor 61 side of the hollow portion 173, and a2 nd frame member 172 disposed on the opposite side of the hollow portion 173 from the motor side. The 1 st frame member 171 and the 2 nd frame member 172 are connected to and integrated with, for example, side wall portions provided so as to surround the hollow portion 173. The 1 st frame member 171 is provided with a through hole h2 that opens into the hollow portion 173 in the axial direction of extension of the reduction mechanism 50. The 1 st frame member 171 is coupled to the extension 52ex of the output member 52 via a coupling member C2 such as a bolt in a state where the coupling portion between the fixed member 51 and the 1 st swing arm 13 is inserted through the through hole h 2. The 1 st frame member 171 is disposed on the motor side of the extension 52ex, and is connected to the extension 52ex from the motor side. The 2 nd frame member 172 may be coupled to the output member 52 from the side opposite to the motor side.

As shown in fig. 3, when viewed in the radial direction of the reduction mechanism 50 (the radial direction of the main bearing 59), the gravity center G17 of the 2 nd arm 17 is located in a range W1 overlapping the rolling surface of the main bearing 59. Here, the center of gravity G17 of the 2 nd arm 17 is a center of gravity of the total weight including the weight of the components that are fixed to the 2 nd arm 17 and do not move (displace) relative to the 2 nd arm 17. That is, in the example of the robot 1 shown in fig. 1, the gravity center G17 of the 2 nd arm is the gravity center of the weight of the components including the 2 nd arm 17 and the 3 rd driving device 23, and the weight of each of the components of the 3 rd arm 21 to the processing head 41 that move relative to the 2 nd arm 17 is excluded.

Fig. 4 is a cross-sectional view showing a joint portion of a comparative example.

In the joint portion of the comparative example, the 1 st rotating arm 13 is coupled to the fixed member 51 from the motor side via the coupling member C11, and the 1 st frame member 171 of the 2 nd arm 17 is coupled to the output member 52 from the side opposite to the motor side via the coupling member C12. In the comparative example, when the main bearing 59 is used as a fulcrum and a point of force of the force applied to the output member 52 in the radial direction is used as the center of gravity G17 of the 2 nd arm 17, the arm L1 becomes long. Therefore, in the case where a load is applied to the speed reduction mechanism 50 in the radial direction from the center of gravity G17 of the 2 nd jib 17, a large moment of the product of the load and the moment arm L1 is applied to the main bearing 59.

On the other hand, in the 2 nd joint portion of the present embodiment shown in fig. 3, when the main bearing 59 is used as a fulcrum and a point of force applied to the output member 52 in the radial direction is used as the center of gravity G17 of the 2 nd arm 17, the moment arm approaches zero. Therefore, in the joint portion of the present embodiment, even if a large load is applied to the speed reduction mechanism 50 in the radial direction from the center of gravity G17 of the 2 nd arm 17, only a small moment is applied to the main bearing 59. Therefore, in the 2 nd joint portion of the present embodiment, the life of the main bearing 59 can be increased as compared with the joint portion of the comparative example.

However, a typical robot arm sometimes includes a multi-joint arm in which a plurality of arms are sequentially connected in such a manner as to rotate in the same direction as each other. Turning in the same direction means that the axes of rotation of the plurality of joints between the arms are parallel to each other. Here, it is assumed that the center of gravity of the main bearing provided in each joint and the arm of the output member connected to the joint are significantly separated in the axial direction as shown in fig. 4. Further, it is assumed that the directions of shifting the centers of gravity of the respective joint portions of the multi-joint arm from the base side to the tip side are the same. In this configuration, the shift of the center of gravity of the plurality of arms from the base side to the tip side is accumulated and acts on the joint portion on the base side, and thus the configuration becomes very unbalanced.

In general, in order to prevent such imbalance, a designer of the articulated arm performs a design in which the shift of the center of gravity of the plurality of arms from the root side to the tip side is not accumulated. Specifically, in a combination of a plurality of joints and an arm connected to the joints, a designer may design the direction of shift of the center of gravity of the arm to be opposite to the direction of shift of the center of gravity of the arm of another joint, so that the shifts of the centers of gravity of the plurality of arms from the root side to the tip side are offset halfway. Further, the design is made in consideration of the weight of each arm and the amount of shift of the center of gravity of the arm in each joint, so that the overall balance is improved.

However, such a design for adjusting the balance is very complicated, and if the specifications of all the arms from the root side to the tip side are not determined, it is difficult to achieve an optimum design.

However, in the 2 nd joint part of the present embodiment, the center of gravity G17 of the 2 nd arm 17 is located at a position overlapping the range of the rolling surface of the main bearing 59 as viewed in the radial direction. Therefore, even when such a joint portion is joined to an arm in order to form a multi-joint arm, the balance is not significantly disturbed due to the accumulation of shifts in the center of gravity of each arm. Therefore, by applying the same configuration as that of the 2 nd driving device 19 and the 2 nd arm 17 of the present embodiment to the plurality of joint portions and the plurality of arms, an advantage that a balanced multi-joint arm of the robot can be easily designed can be obtained. Alternatively, the advantage of the multi-joint arm of the robot arm that can be designed in a balanced manner even if the specifications of all the arms are not determined is also obtained.

Further, according to the 2 nd drive device 19 of the present embodiment, the output member 52 that rotates integrally with the inner ring of the main bearing 59 has the extended portion 52ex that extends to the radially outer side of the fixed member 51 that rotates integrally with the outer ring. The 2 nd arm 17 is coupled to the extension 52 ex. Accordingly, even when a simple form such as a frame shape that is long in one direction is adopted as the 2 nd arm 17, an effect can be obtained that a configuration in which the center of gravity G17 of the 2 nd arm 17 is arranged at a position radially outside the main bearing 59 is easily achieved.

Here, a structure of a comparative example in which a member that rotates integrally with the outer ring of the main bearing 59 is connected to the 2 nd jib 17 and a member that rotates integrally with the inner ring of the main bearing 59 is fixed to the 1 st rotating jib 13 on the base end side is considered. In the structure of this comparative example, the inner ring of the main bearing 59 is stationary and the outer ring rotates. The rolling bearing such as the main bearing 59 has a feature of less sliding wear as compared with the sliding bearing, but it is difficult to completely zero the sliding wear in the rolling bearing. In addition, when the inner ring is stationary and the rotational motion is output from the outer ring, the sliding speed of the rolling elements in the former structure that outputs the rotational motion from the outer ring is higher than that in the case where the same rotational speed is output in the structure that the outer ring is stationary and the rotational motion is output from the inner ring. Therefore, the latter structure that outputs the rotational motion from the inner ring can suppress the generation rate of the sliding wear in the main bearing 59 to be lower. Therefore, in the present embodiment, the 2 nd arm 17 is connected to the output member 52 that rotates integrally with the inner ring of the main bearing 59, whereby the occurrence of sliding wear of the main bearing 59 can be suppressed and the life can be improved as compared with the above comparative example. This structure is particularly effective in a device which is used vigorously like a joint of a robot arm.

Further, according to the 2 nd drive device 19 of the present embodiment, the input bearing 58B on the side opposite to the motor side is a seal bearing. Therefore, it is not necessary to dispose the lubricant seal member 60 (see fig. 4) on the side opposite to the motor side with respect to the input bearing 58B. Therefore, the size of the reduction mechanism 50 in the axial direction can be reduced, and accordingly, the 2 nd arm 17 can be made thinner.

Further, according to the 2 nd drive device 19 of the present embodiment, the 2 nd member 52B of the output member 52 does not protrude further outward in the axial direction than the input bearing 58B on the side opposite to the motor side. Therefore, the axial dimension of the reduction mechanism 50 including the output member 52 can be reduced, and accordingly, the 2 nd arm 17 can be made thinner.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. For example, in the above embodiment, the 1 st arm member 13 is shown as the 1 st arm member according to the present invention, but the shape and structure of the 1 st arm member according to the present invention are not limited as long as the member is a fixed member to which the driving device is fixed. For example, if the driving device according to the present invention is disposed on the most proximal side of the articulated arm, the base member of the articulated arm corresponds to the 1 st arm member according to the present invention. Further, in the embodiment, the multi-joint robot is exemplified, but the type of the robot is not particularly limited, and any robot having the 1 st arm member and the 2 nd arm member can be widely used.

In the above embodiment, the structure in which the main bearing according to the present invention is a set of main bearings is shown. However, the main bearing may be formed of a bearing group in which two or more different bearings are arranged in the axial direction. In this case, the "range of the rolling surface of the rolling element of the main bearing" according to the present invention is defined as a range from the rolling surface located at one end in the axial direction to the rolling surface located at the other end in the axial direction.

In the above embodiment, the speed reduction mechanism of the bending mesh gear device is shown as the speed reduction mechanism 50 provided in the 2 nd joint portion of the manipulator 1. However, as the speed reduction mechanism provided in the drive device for the robot hand according to the present invention, a speed reduction mechanism such as an eccentric oscillation type speed reduction device or a simple planetary speed reduction device that obtains a speed reduction action by oscillating an external gear or an internal gear by an eccentric body may be used. As the eccentric oscillating type reduction gear, a so-called center crank type eccentric oscillating type reduction gear in which an eccentric shaft is disposed at the axial center of the reduction mechanism may be used, or a so-called distributed type eccentric oscillating type reduction gear in which two or more eccentric bodies are disposed at positions offset from the axial center of the reduction mechanism may be used. The detailed configuration shown in the embodiment can be modified as appropriate without departing from the spirit of the invention.

Claims (5)

1. A manipulator including a1 st arm member, a2 nd arm member, and a driving device for driving the 2 nd arm member with respect to the 1 st arm member, the manipulator being characterized in that,

the drive device includes: a fixed member fixed to the 1 st arm member, a speed reduction mechanism, an output member to which rotation reduced by the speed reduction mechanism is transmitted and which is connected to the 2 nd arm member, and a main bearing disposed between the fixed member and the output member,

when viewed in a radial direction of the main bearing, a center of gravity of the 2 nd arm member overlaps with a range of rolling surfaces of rolling elements of the main bearing.

2. The robot hand of claim 1,

the fixed member is rotatable integrally with an outer race of the main bearing,

the output member is rotatable integrally with the inner ring of the main bearing,

the output member has an extension portion extending radially outward of the fixed member, and the 2 nd arm member is coupled to the extension portion.

3. The robot hand according to claim 1 or 2,

further comprising an input bearing disposed between the output member and the input shaft of the speed reduction mechanism,

the input bearing is a sealed bearing having a sealing member.

4. The robot hand of claim 3,

the output member does not protrude axially outward beyond the input bearing when the side on which the main bearing is disposed is an axially inner side.

5. A flexible engagement gear device is provided with: a vibration generator, an external gear which is deformed by the vibration generator in a flexural mode, a1 st internal gear and a2 nd internal gear which mesh with the external gear, and a main bearing which is disposed between the 1 st internal gear and the 2 nd internal gear, wherein the flexural meshing type gear device is characterized in that,

the 1 st internal gear is rotatable integrally with an outer ring of the main bearing, the 2 nd internal gear is rotatable integrally with an inner ring of the main bearing,

the 2 nd internal gear has an extended portion that extends to a radially outer side of an outer ring member that constitutes an outer ring of the main bearing.