WO2022041005A1

WO2022041005A1 - Transmission device, robotic joint, and robot

Info

Publication number: WO2022041005A1
Application number: PCT/CN2020/111518
Authority: WO
Inventors: Yong Yang; Ji Long Yao; Xiao Kuan LIU; Yan Feng Zhao
Original assignee: Rethink Robotics Gmbh; Siemens Ltd., China
Priority date: 2020-08-26
Filing date: 2020-08-26
Publication date: 2022-03-03

Abstract

A transmission device (1) for a robotic joint, comprises: a transmission housing (3); a drive shaft (7) connected to a drive motor (81) of the robotic joint, the drive shaft (7) can be rotated with respect to a central axis (A); a first bearing (60) arranged in the input end of the transmission device (1), the first bearing (60) comprises an inner bearing (61) and an outer bearing (62), the drive shaft (7) is fixed between the inner bearing (61) and the outer bearing (62), and the outer surface of the outer bearing (62) abuts against at least part of the inner wall of the transmission housing (3); a second bearing (40) arranged in the output end of the transmission device (1), the second bearing (40) is fixed to the transmission housing (3); a gearbox (50) comprising a fixed element (51), a drive element (52) and an output element (53), wherein the drive element (52) is connected to the drive shaft (7); an output shaft (45) fixed to the output element (53), the output shaft (45) extends along the central axis (A) direction and supported by the first bearing (60) and the second bearing (40).

Description

TRANSMISSION DEVICE, ROBOTIC JOINT, AND ROBOT

FIELD

The present invention relates to the field of robots, and in particular, to a transmission device, a robotic joint, and a robot.

BACKGROUND

Robots are widely used in the field of intelligent manufacturing. A robotic joint of a robot includes a drive motor and a transmission device. The drive motor and the transmission device are generally integrated into a housing of the robotic joint. The drive motor and the transmission device include a relatively large number of components. The components are time-consuming and laborious in terms of assembly in the housing of the robotic joint and require relatively high assembly precision. If an assembly position is deviated, the robotic joint may produce noise and vibration during operation, which affects the operation of the robotic joint and reduces the service life of the robotic joint.

In addition, the transmission device (for example, a harmonic reducer) of the robotic joint is generally supported by a single bearing, and the transmission device supported by the single bearing forms a cantilever beam structure. When the transmission device receives an output torque of the drive motor, vibration and noise may be produced under a centrifugal force, which may also affect the operation of the robotic joint and reduce the service life of the robotic joint.

SUMMARY

In order to resolve the foregoing technical problems, the present invention provides a transmission device, a robotic joint, and a robot, to eliminate noise and vibration produced by the robotic joint during operation, so that the robotic joint can smoothly operate and the service life of the robotic joint can be improved.

In order to achieve the above objectives, the present invention provides a transmission device for a robotic joint, comprises: a transmission housing; a drive shaft connected to a drive motor of the robotic joint, the drive shaft can be rotated with respect to a central axis A; a first bearing arranged in the input end of the transmission device, the first bearing comprises an inner bearing and an outer bearing, the drive shaft is fixed between the inner bearing and the outer bearing, and the outer surface of the outer bearing abuts against at least part of the inner wall of the transmission housing; a second bearing arranged in the output end of the transmission device, the second bearing (40) abuts against at least part of the inner wall of the transmission housing (3) ; a gearbox comprising a fixed element, a drive element and an output element, wherein the drive element is connected to the drive shaft; an output shaft fixed to the output element, the output shaft extends along the central axis A direction and supported by the first bearing and the second bearing. Therefore, the transmission device is a structure independent of the drive device in the robotic joint, which reduces difficulty of assembling the drive device and the transmission device. The output shaft is supported by a two-point support structure, which improves support stability of the output shaft, avoids noise and vibration produced by the output shaft during rotation due to a centrifugal force, enables the robotic joint to smoothly operate, and improves the service life of the robotic joint.

In one embodiment of the present invention, wherein the transmission device further comprises a torque measuring hub, the torque measuring hub is axially fixed between the fixed element and the second bearing, and at least one torque sensor is arranged on the torque measuring hub. Therefore, accuracy of torque measurement can be improved by arranging the torque measuring hub between the fixed element and the second bearing inside the transmission device.

In one embodiment of the present invention, the torque measuring hub is shaped in annular form and has a recess in the area of the central axis A. Therefore, the torque measuring hub can be adapted to other transmission components to improve compactness of the assembly.

In one embodiment of the present invention, wherein the torque measuring hub comprises a first annular element, a second annular element and a connection element axially connecting the first annular element and the second annular element, the at least one torque sensors are arranged in the surface of the connection element. Therefore, anti-interference of the torque sensor and accuracy of torque measurement can be improved through the torque measuring hub of this structure.

In one embodiment of the present invention, wherein multiple torque sensors are arranged in the surface of the connection element. Therefore, the accuracy of the torque measurement can be further improved by arranging multiple torque sensors.

In one embodiment of the present invention, wherein the multiple torque sensors are evenly arranged in the surface of the connection element. Therefore, the accuracy of the torque measurement can be further improved by arranging multiple evenly distributed torque sensors.

In one embodiment of the present invention, wherein the inner bearing comprises a first inner bearing a and a second inner bearing b, the first inner bearing a is arranged in one end of the drive shaft and the second inner bearing b is arranged in the other end of the drive shaft. Therefore, by arranging the first inner bearing and the second inner bearing on two ends of the drive shaft, the two ends of the drive shaft can be supported, and support stability of the drive shaft can be enhanced.

In one embodiment of the present invention, wherein the gearbox is designed as a Harmonic Transmission gearbox.

In one embodiment of the present invention, wherein the second bearing is designed as a cross rolling bearing. Therefore, the cross rolling bearing includes an inner bearing ring, an outer bearing ring and a cross rolling sandwiched between the inner bearing ring and the outer bearing ring, and the adjacent rollings are axially vertical, which can improve a fixation effect and a support effect of the output shaft.

In one embodiment of the present invention, wherein the inner bearing a and/or outer bearing b is designed as a deep groove ball bearing. Therefore, radial and axial limit and fixation of the output shaft can be achieved.

In one embodiment of the present invention, wherein the output shaft comprises a flange a in the output end of the transmission device, the flange a is fixed to the second bearing. Therefore, a connection effect of the output shaft can be improved by arranging a flange in the output end of the output shaft.

In one embodiment of the present invention, wherein the transmission housing comprises a radial protrusion a, the outer surface of the outer bearing abuts against at least part of the radial protrusion a. Therefore, the outer surface of the outer bearing abutting against the radial protrusion of the transmission housing can reduce the size of the outer bearing and reduce the difficulty of the assembly.

The present invention also provides Robotic joint comprising the transmission device as mentioned above, the robotic joint further comprises a drive device, the drive device comprises a drive motor and a motor housing, the drive shaft of the transmission device is connected to the drive motor.

In one embodiment of the present invention, wherein the diameter of the motor housing is smaller than the diameter of the transmission housing.

The present invention also provides Robot comprising the robotic joint as mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

The following accompanying drawings are intended only to schematically illustrate and explain the present invention and do not limit the scope of the present invention. In the accompanying drawings,

FIG. 1 is a schematic three-dimensional structural diagram of a transmission device of a robotic joint according to an embodiment of the present invention;

FIG. 2 is an axial cross-sectional view of a robotic joint along a rotating central axis according to an embodiment of the present invention;

FIG. 3 is a partially axial cross-sectional view of a transmission device of a robotic joint according to an embodiment of the present invention; and

FIG. 4 is a schematic three-dimensional structural diagram of a torque measuring hub according to an embodiment of the present invention.

Description of Reference Numerals

1 transmission device

3 transmission housing

3a radial protrusion

7 drive shaft

31 torque measuring hub

32 first annular element

33 second annular element

34 connection element

35 torque sensor

36 recess

40 second bearing

45 output shaft

45a flange

50 gearbox

51 fixed element

52 drive element

53 output element

60 first bearing

61 inner bearing

61a first inner bearing

61b second inner bearing

62 outer bearing

80 drive device

81 drive motor

81a rotor

81b stator

82 motor housing

90 robotic joint

91 joint housing

DETAILED DESCRIPTION

In order to have a clearer understanding of the technical features, the objectives, and the effects of the present invention, specific implementations of the present invention are now illustrated with reference to the accompanying drawings.

Many specific details are set forth in the following description to facilitate a full understanding of the present invention, but the present invention may also be implemented in other manners different from those described herein and is therefore not limited by specific embodiments disclosed below.

As shown in the present application and the claims, words such as “a/an, ” “one, ” “one kind, ” and/or “the” do not refer specifically to singular forms and may also include plural forms, unless the context expressly indicates an exception. In general, terms “comprise” and “include” merely indicate including clearly identified steps and elements. The steps and elements do not constitute an exclusive list. A method or a device may also include other steps or elements.

FIG. 1 is a schematic three-dimensional structural diagram of a transmission device of a robotic joint according to an embodiment of the present invention. FIG. 2 is an axial cross-sectional view of a robotic joint along a rotating central axis A according to an embodiment of the present invention. A robotic joint 90 includes a drive device 80 and a transmission device 1 that are arranged in a joint housing 91. The drive device 80 includes a drive motor 81 and a motor housing 82. The drive motor 81 includes a stator 81a and a rotor 81b, the stator 81a is fixed to the motor housing 82, and the rotor 81b can rotate along the rotating center axis A of the robotic joint 90 relative to the stator 81a. The transmission device 1 includes a transmission housing 31. The transmission housing 31 is provided with a transmission component. So far, after the drive device 80 and the transmission device 1 are assembled respectively, the drive device 80 and the transmission device 1 are arranged inside the joint housing 91, and the drive device 80 and the transmission device 1 are independent of each other, which reduces difficulty of assembling the drive device 80 and the transmission device 1, avoids noise and vibration produced by the robotic joint during operation and caused by assembly position deviation, enables the robotic joint to smoothly operate, and improves the service life of the robotic joint.

The transmission device 1 of the robotic joint in an embodiment of the present invention is described below with reference to FIG. 2. As shown in FIG. 2, the transmission device 1 of the robotic joint in the embodiment of the present invention includes a transmission housing 3, a drive shaft 7, a gearbox 50, and an output shaft 45. The transmission housing 3 is located outside the transmission device 1 and is configured to accommodate transmission components, for example, the drive shaft 7, the gearbox 50, and the output shaft 45. The transmission device 1 includes the transmission housing 3 independent of the drive device 80, so that the transmission device 1 is a structure independent of the drive device in the robotic joint 90. The drive shaft 7 is connected to the rotor 81b of the drive motor 81 and can rotate about the rotating central axis A of the robotic joint 90. Torque of the drive shaft 7 is adjusted by the gearbox 50 and then transferred to the output shaft 45. The output shaft 45 may rotate with the adjusted torque with respect to the rotating center axis A of the robotic joint 90.

The transmission device 1 further includes a first bearing 60 arranged in the input end of the transmission device 1. The first bearing 60 supports an input end of the output shaft 45. The first bearing 60 includes an inner bearing 61 and an outer bearing 62. The inner bearing 61 has a smaller radial size than the outer bearing 62. The drive shaft 7 is fixed between the inner bearing and the outer bearing, so that radial and axial movement of the drive shaft 7 is restricted. As shown in FIG. 2, the drive shaft 7 is sandwiched between the inner bearing 61 and the outer bearing 62. The outer surface of the outer bearing 62 abuts against the inner wall of the transmission housing 3, so that the input end of the transmission device 1 is fixed without noise and vibration. In some embodiments, as shown in FIG. 2, the transmission housing 3 may include a radial protrusion 3a, and the outer surface of the outer bearing 62 abuts against the radial protrusion 3a of the transmission housing 3, which may reduce the size of the outer bearing 62 and reduce the difficulty of assembly.

The inner bearing 61 and/or the outer bearing 62 may be a deep groove ball bearing. For example, the outer bearing 62 may be a large deep groove ball bearing, and the inner bearing 61 may be a small deep groove ball bearing. The inner bearing 61 may further include a first inner bearing 61a and a second inner bearing 61b. The first inner bearing 61a is arranged in one end of the drive shaft 7 and the second inner bearing 61b is arranged in the other end of the drive shaft 7. As shown in FIG. 2, the first inner bearing 61a is arranged in the input end of the drive shaft 7 and the second inner bearing 61b is arranged in the output end of the drive shaft 7. By arranging the first inner bearing 61a and the second inner bearing 61b on two ends of the drive shaft 7, the two ends of the drive shaft 7 can be supported and support stability of the drive shaft 7 can be enhanced.

The transmission device 1 further includes a second bearing 40 arranged in an output end of the transmission device 1. The second bearing 40 supports an output end of the output shaft 45 and is fixed to the transmission housing 3. For example, the second bearing 40 may be a cross rolling bearing. The cross rolling bearing includes an inner bearing ring, an outer bearing ring and a cross rolling sandwiched between the inner bearing ring and the outer bearing ring, and the adjacent rollings are axially vertical, which can improve a fixation effect and a support effect of the output shaft.

The gearbox 50 includes a fixed element 51, a drive element 52 and an output element 53. The drive element 52 is connected to the drive shaft 7, and the output element 53 is connected to the output shaft 45. In the embodiment of the present invention, the gearbox 50 may be a harmonic reducer, and the drive shaft 7 may be a wave generator. Specifically, in the harmonic reducer, the fixed element 51 is a rigid wheel, the drive element 52 is a flexible bearing, and the output element 53 is a flexible wheel. The flexible bearing contacts the wave generator, the flexible bearing is radially supported between the wave generator and the flexible wheel, and the rigid wheel is arranged on the outer side of the flexible wheel and engages with the flexible wheel.

The output shaft 45 is fixed to the output element 53 of the gearbox 50. The output shaft 45 extends along the direction of the rotating central axis A and is supported by the first bearing 60 and the second bearing 40. As shown in FIG. 2, the input end of the output shaft 45 is supported by the first bearing 60, and the output end is supported by the second bearing 40. The output shaft 45 includes a flange 45a. The flange 45a is located in the output end of the transmission device 1, and the flange 45a is fixed and connected to the second bearing 40.

So far, the embodiment of the present invention provides a transmission device for a robotic joint. The transmission device 1 is provided with a first bearing 60 and a second bearing 40, the first bearing 60 supports the input end of the output shaft 45, the second bearing 40 supports the output end of the output shaft 45, and both the first bearing 60 and the second bearing 40 are fixed in transmission housing 3 side, thus providing a two-point support structure for the output shaft 45, which improves support stability of the output shaft 45, avoids noise and vibration produced by the output shaft 45 during rotation due to a centrifugal force, enables the robotic joint to smoothly operate, and improves the service life of the robotic joint.

The transmission device 1 further includes a torque measuring hub 31. The torque measuring hub 31 is axially arranged between the fixed element 51 of the gearbox 50 and the second bearing 40, and the torque measuring hub 31 is fixed and connected to the fixed element 51 and the second bearing 40. The torque measuring hub 31 is fixed and connected to the fixed element 51 and the second bearing 40, torque received by the fixed element 51 may be transferred to the torque measuring hub 31, and a torque sensor 35 on the torque measuring hub 31 may measure the torque. Accuracy of torque measurement can be improved by arranging the torque measuring hub 31 between the fixed element 51 and the second bearing 40 inside the transmission device 1.

FIG. 3 is a schematic partial cross-sectional structural diagram of a transmission device 1 according to an embodiment of the present invention. FIG. 4 is a schematic three-dimensional structural diagram of a torque measuring hub 31 according to an embodiment of the present invention.

As shown in FIG. 3 and FIG. 4, the torque measuring hub 31 is axially arranged between the fixed element 51 of the gearbox 50 and the second bearing 40, and the torque measuring hub 31 is fixed and connected to the fixed element 51 and the second bearing 40. The torque measuring hub 31 is provided with at least one torque sensor 35, for measuring torque. The torque measuring hub 31 is shaped in annular form and has a recess 36 in the area of the central axis A. The recess 36 is used for the output shaft 45 to pass through.

The torque measuring hub 31 includes a first annular element 32, a second annular element 33 and a connection element 34 axially connecting the first annular element 32 and the second annular element 33, and the at least one torque sensors 35 are arranged in the surface of the connection element 34. The torque measuring hub 31 deforms under the torque, and the torque sensor 35 can measure the torque through the deformation. Preferably, the torque measuring hub 31 may be provided with multiple torque sensors 35. The multiple torque sensors 35 may be identical torque sensors, for example, all are strain gauges. The multiple torque sensors 35 may be evenly arranged in a circumferential direction of the torque measuring hub 31. As a non-restrictive example, four torque sensors 35 may be arranged in 12 o’clock, 3 o’clock, 6 o’clock, and 9 o’clock directions of the torque measuring hub 31.

The present invention further provides a robotic joint 90. The robotic joint 90 includes the transmission device 1 arranged in the joint housing 91 as described in the foregoing. The robotic joint 90 further includes a drive device 80 arranged in the joint housing 91. The drive device 80 includes a drive motor 81 and a motor housing 82. The drive shaft 7 of the transmission device 1 is connected to the drive motor 81. The drive device 80 includes the motor housing 82, the transmission device 1 includes a transmission housing 31, and the motor housing 82 and the transmission housing 31 may be arranged inside the joint housing 91 after the drive device 80 and the transmission device 1 are assembled respectively. The drive device 80 and the transmission device 1 are independent of each other, which reduces the difficulty of assembling the drive device 80 and the transmission device 1, may avoid noise and vibration produced by the robotic joint during operation caused by assembly position deviation, enables the robotic joint to smoothly operate, and improves the service life of the robotic joint.

The present invention further provides a robot. The robot includes the robotic joint 90 as described in the foregoing. The robot has the effect of smooth operation of the robotic joint 90, and the descriptions thereof are omitted herein.

It should be understood that, although this specification is described according to various embodiments, not each embodiment includes only a separate technical solution. The specification is described in such a manner only for the sake of clarity. A person skilled in the art should take the specification as a whole, and the technical solutions in various embodiments may also be appropriately combined to form other implementations that can be understood by the person skilled in the art.

The foregoing are merely specific schematic implementations of the present invention and are not intended to limit the scope of the present invention. Any equivalent change, modification, and combination made by the person skilled in the art without departing from the conception and principles of the present invention should all fall within the protection scope of the present invention.

Claims

Transmission device (1) for a robotic joint, comprises:

a transmission housing (3) ;

a drive shaft (7) connected to a drive motor (81) of the robotic joint, the drive shaft (7) can be rotated with respect to a central axis (A) ;

a first bearing (60) arranged in the input end of the transmission device (1) , the first bearing (60) comprises an inner bearing (61) and an outer bearing (62) , the drive shaft (7) is fixed between the inner bearing (61) and the outer bearing (62) , and the outer surface of the outer bearing (62) abuts against at least part of the inner wall of the transmission housing (3) ;

a second bearing (40) arranged in the output end of the transmission device (1) , the second bearing (40) is fixed to the transmission housing (3) ;

a gearbox (50) comprising a fixed element (51) , a drive element (52) and an output element (53) , wherein the drive element (52) is connected to the drive shaft (7) ;

an output shaft (45) fixed to the output element (53) , the output shaft (45) extends along the central axis (A) direction and supported by the first bearing (60) and the second bearing (40) .
Transmission device (1) according to claim 1, wherein the transmission device (1) further comprises a torque measuring hub (31) , the torque measuring hub (31) is axially fixed between the fixed element (51) and the second bearing (40) , and at least one torque sensor is arranged on the torque measuring hub (31) .
Transmission device (1) according to one of the preceding claims, the torque measuring hub (31) is shaped in annular form and has a recess (36) in the area of the central axis (A) .
Transmission device (1) according to one of the preceding claims, wherein the torque measuring hub (31) comprises a first annular element (32) , a second annular element (33) and a connection element (34) axially connecting the first annular element (32) and the second annular (33) element, the at least one torque sensors (35) are arranged in the surface of the connection element (34) .
Transmission device (1) according to one of the preceding claims, wherein multiple torque sensors (35) are arranged in the surface of the connection element (34) .
Transmission device (1) according to one of the preceding claims, wherein the multiple torque sensors (35) are evenly arranged in the surface of the connection element (34) .
Transmission device (1) according to one of the preceding claims, wherein the inner bearing (61) comprises a first inner bearing (61a) and a second inner bearing (61b) , the first inner bearing (61a) is arranged in one end of the drive shaft (7) and the second inner bearing (61b) is arranged in the other end of the drive shaft (7) .
Transmission device (1) according to one of the preceding claims, wherein the gearbox (50) is designed as a Harmonic Transmission gearbox.
Transmission device (1) according to one of the preceding claims, wherein the second bearing (40) is designed as a cross rolling bearing.
Transmission device (1) according to one of the preceding claims, wherein the inner bearing (61a) and/or outer bearing (61b) is designed as a deep groove ball bearing.
Transmission device (1) according to one of the preceding claims, wherein the output shaft (45) comprises a flange (45a) in the output end of the transmission device (1) , the flange (45a) is fixed to the second bearing (40) .
Transmission device (1) according to one of the preceding claims, wherein the transmission housing (3) comprises a radial protrusion (3a) , the outer surface of the outer bearing (62) abuts against at least part of the radial protrusion (3a) .
Robotic joint comprising the transmission device (1) according to any one of claim 1-12, the robotic joint further comprises a drive device (80) , the drive device (80) comprises a drive motor (81) and a motor housing (82) , the drive shaft (7) of the transmission device (1) is connected to the drive motor (81) .
Robotic joint according to claim 13, wherein the diameter of the motor housing (82) is smaller than the diameter of the transmission housing (3) .
Robot comprising the robotic joint according to claim 13 or 14.