Speed reducer for robot joint

Abstract

The invention relates to a speed reducer for a robot joint. The speed reducer comprises an inner gear shell, a high-speed input hollow shaft, a first cycloidal gear, a second cycloidal gear, a first roller pin set, a second roller pin set, a pin shaft, an output flange plate and a low-speed output hollow shaft. A first cam and a second cam are integrally arranged on the circumferential outer wall of the high-speed input hollow shaft; the high-speed input hollow shaft is sleeved with the first cycloidal gear and the second cycloidal gear. The first roller pin set and the second roller pin set are arranged along the driving contours of the first cam and the second cam respectively. A plurality of pin shafts which are circumferentially distributed along the rotation axis of the output flange plate are fixedly arranged on the output flange plate; the pin shaft correspondingly penetrates through the pin shaft holes in the first cycloidal gear and the second cycloidal gear in sequence; the output flange plate is rotationally arranged in the inner gear housing; and the low-speed output hollow shaft on the output flange plate penetrates through the high-speed input hollow shaft. The invention has the characteristics of small axial size, high torque and high rigidity.

Description

Technical Field

[0001] The present invention relates to the field of robots, and particularly to a speed reducer for a robot joint. Background Art

[0002] With the aggravation of the global aging problem and the rise of labor costs, industrial robots have gradually replaced the previous manual labor and have good prospects for future development. In various industrial applications, the performance of robot joints has a direct impact on the efficiency and accuracy of the overall robot. As the core component of robot technology, the development of the robot joint drive module has gone through multiple stages, from the early simple mechanical transmission to the modern high-precision and high-integration drive system.

[0003] Most traditional robot joints use permanent magnet synchronous motors and drivers as the power source, and their output torque and speed are designed according to the rated indicators of the joints. However, this design has obvious limitations when facing complex environments and high torque and high-precision requirements, affecting the high-precision operation of the robot.

[0004] In order to meet the high torque and high-precision requirements of modern robots, researchers have begun to integrate the motor with a harmonic reducer or a cycloidal speed reducer. Since the harmonic reducer or the cycloidal speed reducer has a high reduction ratio, it can provide high torque and can meet the high-precision requirements.

[0005] For the convenience of motor control and to achieve high output position accuracy of the speed reducer, an encoder is included on the servo motor side for motor control. An absolute encoder is also installed at the output end of the speed reducer for final angle closed-loop control. In a robot joint, since the two encoders need to be set at the motor end and the speed reducer end respectively, the axial dimension has not been able to be compressed currently. And at the robot joint, the compression of the axial dimension is very crucial for the robot joint. Therefore, further optimization of the design is needed. Summary of the Invention

[0006] The object of the present invention is a speed reducer for a robot joint, which utilizes the cycloidal reduction principle to have high torque, high rigidity and high precision, so that the robot joint drive module has high torque, high precision and high rigidity. At the same time, the low-speed output hollow shaft of the speed reducer is led out from the input end, which provides favorable conditions for reducing the axial dimension, and provides favorable conditions for guiding and installing the output induction encoder of the speed reducer into the controller of the power input device, that is, provides favorable conditions for integrating the speed reducer with the control unit of the power input device, and further reduces the axial dimension.

[0007] The technical solution for achieving the object of the present invention is as follows: The present invention includes an internal gear housing, a high-speed input hollow shaft, a first cycloid gear, a second cycloid gear, a first set of needle rollers, a second set of needle rollers, a pin shaft, an output flange, and a low-speed output hollow shaft; The high-speed input hollow shaft is provided with a first through hole coaxial therewith; on the circumferential outer wall of the high-speed input hollow shaft, a first cam and a second cam are integrally provided; the first set of needle rollers is a plurality of needle rollers closely arranged along the driving profile of the first cam, and the axial direction of the needle rollers is the same as the axial direction of the high-speed input hollow shaft; the second set of needle rollers is a plurality of needle rollers closely arranged along the driving profile of the second cam, and the axial direction of the needle rollers is the same as the axial direction of the high-speed input hollow shaft; Both the first cycloid gear and the second cycloid gear are provided with an input hole, an external gear ring, and pin shaft holes distributed around the input hole; the first cycloid gear is sleeved on the high-speed input hollow shaft, and the first cam is located in its input hole, and the first set of needle rollers is arranged between the inner wall of the input hole and the driving profile of the first cam; the second cycloid gear is sleeved on the high-speed input hollow shaft, and the second cam is located in its input hole, and the second set of needle rollers is arranged between the inner wall of the input hole and the driving profile of the second cam; the external gear rings of the first cycloid gear and the second cycloid gear form a cycloid engagement with the internal gear ring on the inner wall of the internal gear housing under the driving of the rotation of the high-speed input hollow shaft; On the output flange, a plurality of pin shafts are fixedly provided and circumferentially distributed along the rotation axis of the output flange; the pin shafts sequentially pass through the pin shaft holes on the first cycloid gear and the pin shaft holes on the second cycloid gear correspondingly; the output flange is rotatably arranged in the internal gear housing; the output flange is located at one end of the high-speed input hollow shaft away from its input end; a low-speed output hollow shaft is integrally provided at the center of the output flange; the low-speed output hollow shaft is provided with a second through hole coaxial therewith; the high-speed input hollow shaft and the low-speed output hollow shaft are located on the same axis; the low-speed output hollow shaft passes through the first through hole of the high-speed input hollow shaft; the cycloid motion of the first cycloid gear and the second cycloid gear drives the pin shafts to drive the output flange to rotate, and drives the low-speed output hollow shaft to rotate.

[0008] Further, it further includes a bracket ring; the bracket ring is sleeved outside the high-speed input hollow shaft, and the bracket ring is rotatably arranged in the internal gear housing; the first cycloid gear and the second cycloid gear are arranged between the output flange and the bracket ring; both ends of the pin shaft are fixedly connected to the output flange and the bracket ring respectively; both the output flange and the bracket ring are rotatably arranged in the internal gear housing through bearings.

[0009] Further, a collar is sleeved on each pin shaft; the collar is located in the pin shaft holes of the first cycloid gear and the second cycloid gear; the collar is located between the output flange and the bracket ring; the collar is rotatably matched with the pin shaft.

[0010] Further, one end of the low-speed output hollow shaft passing through the first through-hole is used to connect with an encoder. A thin-type inductive encoder can be adopted for the encoder. The thin-type inductive encoder is sleeved on the low-speed output hollow shaft, and its rotor body is fixedly connected with the low-speed output hollow shaft.

[0011] Further, a grease groove is provided on the circumferential surface of the pin shaft. The sliding resistance between the pin shaft and the collar can be reduced through the grease groove.

[0012] Further, the above-mentioned grease groove is a spiral line extending along the axis direction of the pin shaft. Through the grease groove in a spiral state, with the force application mode of the first cycloid gear and the second cycloid gear pushing the collar, the grease can better participate in lubrication.

[0013] Further, a first guard plate and a second guard plate are sleeved on the above-mentioned high-speed input hollow shaft; the first cycloid gear and the second cycloid gear are located between the first guard plate and the second guard plate; a limiting space for the first needle roller group and the second needle roller group is formed between the first guard plate and the second guard plate, and with the cycloid motion of the first cycloid gear and the second cycloid gear, the first guard plate and the second guard plate limit the first needle roller group and the second needle roller group from disengaging from the limiting space.

[0014] Further, the above-mentioned internal tooth shell includes a mounting ring body and a reducer end cover; an internal tooth ring is provided on the annular inner wall of the mounting ring body, and a flange edge is provided on the outer circumferential surface of the mounting ring body; one side of the flange edge of the mounting ring body is fixedly connected with the reducer end cover, and the other side is used for mounting and connection; the reducer end cover and the flange edge of the mounting ring body are fixedly connected together through fixing bolts, and the other side of the flange edge of the mounting ring body can be used for fixedly connecting with a power input device, such as a motor.

[0015] Further, mounting jacks corresponding to the pin shafts one by one are provided on the end surface of the bracket ring facing the pin shaft; the outer edge of the bracket ring near the input end of the high-speed input hollow shaft forms a radially outward extending outer flanging, and the inner edge of the bracket ring near the input end of the high-speed input hollow shaft forms a radially inward extending inner flanging; one end of the pin shaft fixedly connected with the bracket ring is inserted into the mounting jack of the bracket ring and then fixedly connected with the bracket ring; A first bearing installation chamber is formed between the outer flanging and the step on the inner wall of the corresponding mounting ring body; a second bearing installation chamber is formed by the step on the outer circumferential surface of the output flange, the step on the inner wall of the reducer end cover, and the mounting ring body; A third bearing installation chamber is formed between the inner flanging and the second cam; a fourth bearing installation chamber is formed by the step on the inner circumferential surface of the output flange and the first cam; A first bearing, a second bearing, a third bearing, and a fourth bearing are respectively provided in the first bearing installation chamber, the second bearing installation chamber, the third bearing installation chamber, and the fourth bearing installation chamber; The overall formed by the fixed connection of the output flange with the pin shaft and the bracket ring is rotationally connected to the internal gear housing through the first bearing and the second bearing; the overall formed by the fixed connection of the output flange with the pin shaft and the bracket ring is rotationally connected to the high-speed input hollow shaft through the third bearing and the fourth bearing.

[0016] Furthermore, the first bearing and the third bearing are coaxially arranged; the second bearing and the fourth bearing are coaxially arranged.

[0017] The present invention has positive effects: (1) The present invention utilizes the cycloid deceleration principle to have high torque, high rigidity and high precision, so that the robot joint drive module has high torque, high precision and high rigidity. At the same time, the present invention leads out the low-speed output hollow shaft of the speed reducer from the input end, which provides favorable conditions for reducing the axial dimension, and provides favorable conditions for guiding and installing the output induction encoder of the speed reducer into the controller of the power input device, that is, provides favorable conditions for integrating the speed reducer and the control unit of the power input device, and further reduces the axial dimension.

[0018] (2) Based on introducing the low-speed output hollow shaft of the speed reducer into the controller installation cavity of the power input device, the structure of the traditional cycloid speed reducer cannot meet this requirement. Therefore, through improved design, the present invention enables the cycloid speed reducer to be combined with the power input device.

[0019] (3) The second through hole on the low-speed output hollow shaft of the speed reducer in the present invention can be used as a wire routing through hole, which is convenient for the arrangement and threading of robot cables.

[0020] (4) The present invention can reduce the sliding resistance between the pin shaft and the collar through the grease groove. At the same time, through the grease groove in a spiral state, with the force application mode of the first cycloid gear and the second cycloid gear pushing the collar, the grease can better participate in lubrication.

[0021] (5) Since the high-speed input hollow shaft in the present invention is a hollow body, there is no suitable deflector sleeve in the existing cycloid speed reducer. Based on this, the first cam and the second cam are integrally arranged with the high-speed input hollow shaft, and the stiffness can meet the driving requirements; at the same time, the first needle roller group and the second needle roller group are used to reduce wear. Such a design provides favorable conditions for guiding the low-speed output hollow shaft of the speed reducer to the controller installation cavity of the motor drive mechanism.

[0022] (6) The present invention can prevent the needle rollers from detaching and getting stuck with the bearings through the first guard plate and the second guard plate, thereby ensuring the smooth operation of the robot joint drive module.

[0023] (7) Through the cooperation of the first bearing, the second bearing, the third bearing and the fourth bearing, the present invention enables the overall structure formed by the fixed connection of the output flange, the pin shaft and the bracket ring to rotate better within the internal gear housing, and further improves the coaxiality and load-bearing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments in conjunction with the drawings, where Figure 1 is the structural schematic diagram of the present invention; Figure 2 is the axial sectional view of the speed reducer in the present invention; Figure 3 is the radial sectional view of the speed reducer in the present invention; Figure 4 is the explosion schematic diagram of the speed reducer in the present invention; Figure 5 is the assembly schematic diagram of the first cycloid gear, the second cycloid gear, the pin shaft and the collar in the present invention; Figure 6 is the structural schematic diagram of the first cycloid gear in the present invention; Figure 7 is the structural schematic diagram of the high-speed input hollow shaft in the present invention; Figure 8 is the cooperation schematic diagram of the high-speed input hollow shaft, the first needle roller group, the second needle roller group, the first guard plate and the second guard plate in the present invention; Figure 9 is the structural schematic diagram of the pin shaft in the present invention; Figure 10 is the structural schematic diagram of the bracket ring in the present invention; Figure 11 is the structural schematic diagram of the output flange in the present invention.

[0025] In the figure, internal gear housing 1, mounting ring body 11, speed reducer end cover 12, internal gear ring 111, flange edge 112, high-speed input hollow shaft 2, first through hole 21, first cam 22, second cam 23, first cycloid gear 3, input hole 31, external gear ring 32, pin shaft hole 33, first guard plate 34, second guard plate 35, second cycloid gear 4, first needle roller group 5, second needle roller group 6, pin shaft 7, collar 71, grease groove 72, output flange 8, low-speed output hollow shaft 81, second through hole 811, bracket ring 9, mounting socket 91, outer flanging 92, inner flanging 93, first bearing a, second bearing b, third bearing c, fourth bearing d. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] See Figures 1 to 11, the present invention includes an internal gear housing 1, a high-speed input hollow shaft 2, a first cycloid gear 3, a second cycloid gear 4, a first set of needle rollers 5, a second set of needle rollers 6, a pin shaft 7, an output flange 8, and a low-speed output hollow shaft 81; The high-speed input hollow shaft 2 is provided with a first through hole 21 coaxial therewith; on the circumferential outer wall of the high-speed input hollow shaft 2, a first cam 22 and a second cam 23 are integrally provided; the first set of needle rollers 5 is a plurality of needle rollers closely arranged along the driving profile of the first cam 22, and the axial direction of the needle rollers is the same as the axial direction of the high-speed input hollow shaft 2; the second set of needle rollers 6 is a plurality of needle rollers closely arranged along the driving profile of the second cam 23, and the axial direction of the needle rollers is the same as the axial direction of the high-speed input hollow shaft 2; Both the first cycloid gear 3 and the second cycloid gear 4 are provided with an input hole 31, an outer gear ring 32, and pin shaft holes 33 distributed around the input hole 31; the first cycloid gear 3 is sleeved on the high-speed input hollow shaft 2, and the first cam 22 is located in its input hole 31, and the first set of needle rollers 5 is arranged between the inner wall of the input hole 31 and the driving profile of the first cam 22; the second cycloid gear 4 is sleeved on the high-speed input hollow shaft 2, and the second cam 23 is located in its input hole 31, and the second set of needle rollers 6 is arranged between the inner wall of the input hole 31 and the driving profile of the second cam 23; the outer gear rings 32 of the first cycloid gear 3 and the second cycloid gear 4 form a cycloid meshing with the internal gear ring 111 on the inner wall of the internal gear housing 1 under the driving of the rotation of the high-speed input hollow shaft 2.

[0027] Among them, the internal gear ring 111 of the internal gear housing 1 adopts a hypocycloid curve tooth profile, and the outer gear rings 32 of the first cycloid gear 3 and the second cycloid gear 4 also adopt a hypocycloid curve tooth profile. The reason for not adopting an involute tooth profile is that the involute tooth profile will result in a smaller number of meshing teeth and cycloid interference will occur.

[0028] Secondly, the combination of the number of teeth of the internal gear ring 111 and the outer gear ring 32 is relatively prime to each other. In this embodiment, the number of teeth of the internal gear ring 111 is 41 teeth, and the number of teeth of the outer gear ring 32 is 39 teeth.

[0029] When the safety factor of the rated torque is 1, 1.6 times the Hertz stress is the Hertz stress limit torque. 2.5 times the tooth root bending stress is the limit torque value. The maximum load torque of the speed reducer takes the above minimum value.

[0030] A plurality of pin shafts 7 are fixedly arranged on the output flange 8 and are circumferentially distributed along the rotation axis of the output flange 8; the pin shafts 7 sequentially pass through the pin holes 33 on the first cycloid gear 3 and the pin holes 33 on the second cycloid gear 4; the output flange 8 is rotatably arranged in the internal tooth housing 1; the output flange 8 is located at one end of the high-speed input hollow shaft 2 away from its input end; a low-speed output hollow shaft 81 is integrally provided at the center of the output flange 8; the low-speed output hollow shaft 81 is provided with a second through hole 811 coaxial with it; the second through hole 811 can be used as a wire routing hole for the robot cable; the high-speed input hollow shaft 2 and the low-speed output hollow shaft 81 are located on the same axis; the low-speed output hollow shaft 81 passes through the first through hole 21 of the high-speed input hollow shaft 2; the cycloid motion of the first cycloid gear 3 and the second cycloid gear 4 drives the pin shafts 7 to drive the output flange 8 to rotate and drive the low-speed output hollow shaft 81 to rotate.

[0031] It further includes a bracket ring 9; the bracket ring 9 is sleeved outside the high-speed input hollow shaft 2, and the bracket ring 9 is rotatably arranged in the internal tooth housing 1; the first cycloid gear 3 and the second cycloid gear 4 are arranged between the output flange 8 and the bracket ring 9; both ends of the pin shaft 7 are fixedly connected to the output flange 8 and the bracket ring 9 respectively; both the output flange 8 and the bracket ring 9 are rotatably arranged in the internal tooth housing 1 through bearings.

[0032] A collar 71 is also sleeved on each pin shaft 7; the collar 71 is located in the pin holes 33 of the first cycloid gear 3 and the second cycloid gear 4; the collar 71 is located between the output flange 8 and the bracket ring 9; the collar 71 is rotationally matched with the pin shaft 7.

[0033] One end of the low-speed output hollow shaft 81 passing out of the first through hole 21 is used to connect with an encoder. A thin-type inductive encoder can be used as the encoder. The thin-type inductive encoder is sleeved on the low-speed output hollow shaft 81 and fixedly installed in the controller, and its rotor body is fixedly connected to the low-speed output hollow shaft 81.

[0034] A grease groove 72 is provided on the circumferential surface of the pin shaft 7. The grease groove 72 can reduce the sliding resistance between the pin shaft 7 and the collar 71.

[0035] The grease groove 72 is a spiral line extending along the axis of the pin shaft 7. Through the grease groove 72 in a spiral state, with the force application method of the first cycloid gear 3 and the second cycloid gear 4 pushing the collar 71, the grease can better participate in lubrication.

[0036] A first guard plate 34 and a second guard plate 35 are sleeved on the high-speed input hollow shaft 2; the first cycloid gear 3 and the second cycloid gear 4 are located between the first guard plate 34 and the second guard plate 35; a limiting space for a first needle roller group 5 and a second needle roller group 6 is formed between the first guard plate 34 and the second guard plate 35, and with the cycloid motion of the first cycloid gear 3 and the second cycloid gear 4, the first guard plate 34 and the second guard plate 35 limit the first needle roller group 5 and the second needle roller group 6 from disengaging from the limiting space.

[0037] The internal gear housing 1 includes a mounting ring body 11 and a reducer end cover 12; an internal gear ring 111 is provided on the annular inner wall of the mounting ring body 11, and a flange edge 112 is provided on the outer circumferential surface of the mounting ring body 11; one side of the flange edge 112 of the mounting ring body 11 is fixedly connected to the reducer end cover 12, and the other side is for the installation of the reducer (i.e., for fixedly connecting to the power input device); the reducer end cover 12 and the flange edge 112 of the mounting ring body 11 are fixedly connected together by fixing bolts, and the other side of the flange edge 112 of the mounting ring body 11 can be used for fixedly connecting to the power input device, such as a motor.

[0038] On the end face of the bracket ring 9 facing the pin shaft 7, mounting jacks 91 corresponding to the pin shaft 7 one by one are provided; on the outer edge of the bracket ring 9 near the input end of the high-speed input hollow shaft 2, an outer flanging 92 extending radially outward is formed, and on the inner edge of the bracket ring 9 near the input end of the high-speed input hollow shaft 2, an inner flanging 93 extending radially inward is formed; one end of the pin shaft 7 fixedly connected to the bracket ring 9 is inserted into the mounting jack 91 of the bracket ring 9 and then fixedly connected to the bracket ring 9; A first bearing installation chamber is formed between the outer flanging 92 and the step on the inner wall of the corresponding mounting ring body 11; a second bearing installation chamber is formed by the step on the outer circumferential surface of the output flange 8, the step on the inner wall of the reducer end cover 12, and the mounting ring body 11; A third bearing installation chamber is formed between the inner flanging 93 and the second cam 23; a fourth bearing installation chamber is formed between the step on the inner circumferential surface of the output flange 8 and the first cam 23; A first bearing a, a second bearing b, a third bearing c, and a fourth bearing d are respectively provided in the first bearing installation chamber, the second bearing installation chamber, the third bearing installation chamber, and the fourth bearing installation chamber; The overall formed by the fixed connection of the output flange 8 with the pin shaft 7 and the bracket ring 9 is rotationally connected to the internal gear housing 1 through the first bearing a and the second bearing b; the overall formed by the fixed connection of the output flange 8 with the pin shaft 7 and the bracket ring 9 is rotationally connected to the high-speed input hollow shaft 2 through the third bearing c and the fourth bearing d.

[0039] The first bearing a and the third bearing c are coaxially arranged; the second bearing b and the fourth bearing d are coaxially arranged.

[0040] The working process of the present invention is as follows: First, driven by the power input device, the high-speed input hollow shaft 2 rotates. The first cam 22 and the second cam 23 on the high-speed input hollow shaft 2 drive the first cycloid gear 3 and the second cycloid gear 4 to perform cycloid motion under the cooperation drive of the first needle roller group 5 and the second needle roller group 6, and promote the first cycloid gear 3 and the second cycloid gear 4 to perform cycloid meshing motion with the internal gear ring 111.

[0041] Next, the first cycloid gear 3 and the second cycloid gear 4 push the pin shaft 7 through their cycloid motion, and promote the output flange 8 to rotate at a low speed; the rotation of the output flange 8 drives the low-speed output hollow shaft 81 to rotate synchronously.

[0042] Since the speed reducer utilizes the cycloid deceleration principle, it has characteristics such as high torque and high rigidity. At the same time, supported by the first bearing a, the second bearing b, the third bearing c, and the fourth bearing d, the output flange 8 has higher load-bearing capacity.

[0043] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A reducer for a robot joint, characterized in that: It includes an inner gear housing, a high-speed input hollow shaft, a first cycloid wheel, a second cycloid wheel, a first needle roller group, a second needle roller group, a pin shaft, an output flange and a low-speed output hollow shaft; The high-speed input hollow shaft is provided with a first through hole coaxial therewith; a first cam and a second cam are integrally provided on the circumferential outer wall of the high-speed input hollow shaft; the first needle roller group is a plurality of needle rollers closely arranged along the driving profile of the first cam, and the axial direction of the needle rollers is consistent with the axial direction of the high-speed input hollow shaft; the second needle roller group is a plurality of needle rollers closely arranged along the driving profile of the second cam, and the axial direction of the needle rollers is consistent with the axial direction of the high-speed input hollow shaft; The first cycloid wheel and the second cycloid wheel are both provided with an input hole, an outer gear ring, and pin holes distributed around the input hole; the first cycloid wheel is sleeved on the high-speed input hollow shaft, and the first cam is located in its input hole, and the first needle roller group is arranged between the inner wall of the input hole and the driving profile of the first cam; the second cycloid wheel is sleeved on the high-speed input hollow shaft, and the second cam is located in its input hole, and the second needle roller group is arranged between the inner wall of the input hole and the driving profile of the second cam; under the rotation drive of the high-speed input hollow shaft, the outer gear rings of the first cycloid wheel and the second cycloid wheel form cycloidal meshing with the inner gear ring on the inner wall of the inner gear housing; The output flange is fixed with a plurality of pins distributed along the circumference of the rotation axis of the output flange; the pins pass through the pin holes on the first cycloidal wheel and the pin holes on the second cycloidal wheel in sequence; the output flange is rotatably arranged in the inner gear housing; the output flange is located at the end of the high-speed input hollow shaft away from its input end; a low-speed output hollow shaft is integrally provided at the center of the output flange; the low-speed output hollow shaft is provided with a second through hole coaxial with the high-speed input hollow shaft; the high-speed input hollow shaft and the low-speed output hollow shaft are located on the same axis; the low-speed output hollow shaft passes through the first through hole of the high-speed input hollow shaft; the cycloidal motion of the first cycloidal wheel and the second cycloidal wheel pushes the pins to drive the output flange to rotate, and drive the low-speed output hollow shaft to rotate.

2. A reducer for a robot joint according to claim 1, characterized in that: It also includes a bracket ring; the bracket ring is sleeved on the outside of the high-speed input hollow shaft, and the bracket ring is rotatably arranged in the inner gear housing; the first cycloidal wheel and the second cycloidal wheel are arranged between the output flange and the bracket ring; the two ends of the pin shaft are fixedly connected to the output flange and the bracket ring respectively; the output flange and the bracket ring are both rotatably arranged in the inner gear housing through bearings.

3. A reducer for a robot joint according to claim 2, characterized in that: Each pin shaft is also sleeved with a collar; the collar is located in the pin shaft holes of the first cycloid wheel and the second cycloid wheel; the collar is located between the output flange and the bracket ring; the collar is rotatably matched with the pin shaft.

4. A reducer for a robot joint according to claim 1, characterized in that: One end of the low-speed output hollow shaft passing through the first through hole is used for connecting with an encoder.

5. A reducer for a robot joint according to claim 1, characterized in that: A grease groove is provided on the circumferential surface of the pin shaft.

6. A reducer for a robot joint according to claim 5, characterized in that: The grease groove is a spiral line extending along the axial direction of the pin shaft.

7. A reducer for a robot joint according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that: The high-speed input hollow shaft is provided with a first guard plate and a second guard plate; the first cycloidal wheel and the second cycloidal wheel are located between the first guard plate and the second guard plate; a restricted space for the first needle roller group and the second needle roller group is formed between the first guard plate and the second guard plate, and with the cycloidal movement of the first cycloidal wheel and the second cycloidal wheel, the first guard plate and the second guard plate restrict the first needle roller group and the second needle roller group from leaving the restricted space.

8. The reducer for a robot joint according to claim 1, characterized in that: The inner gear housing includes a mounting ring body and a reducer end cover; an inner gear ring is provided on the annular inner wall of the mounting ring body, and a flange edge is provided on the outer circumferential surface of the mounting ring body; one side of the flange edge of the mounting ring body is fixedly connected to the reducer end cover, and the other side is used for mounting connection.

9. A reducer for a robot joint according to claim 8, characterized in that: The end surface of the bracket ring facing the pin shaft is provided with a mounting socket corresponding to the pin shaft one by one; the outer edge of the bracket ring close to the input end of the high-speed input hollow shaft forms an outer flange extending radially outward, and the inner edge of the bracket ring close to the input end of the high-speed input hollow shaft forms an inner flange extending radially inward; one end of the pin shaft fixedly connected to the bracket ring is inserted into the mounting socket of the bracket ring and fixedly connected to the bracket ring; A first bearing installation chamber is formed between the outer flange and the step on the inner wall of the mounting ring body on the corresponding side; a second bearing installation chamber is formed by the step on the outer circumferential surface of the output flange, the step on the inner wall of the reducer end cover and the mounting ring body; A third bearing installation chamber is formed between the inner flange and the second cam; a fourth bearing installation chamber is formed between the step on the inner circumferential surface of the output flange and the first cam; The first bearing installation chamber, the second bearing installation chamber, the third bearing installation chamber and the fourth bearing installation chamber are respectively provided with a first bearing, a second bearing, a third bearing and a fourth bearing; The output flange, the pin shaft and the bracket ring are fixedly connected to form a whole that is rotatably connected to the inner gear housing through the first bearing and the second bearing; the output flange, the pin shaft and the bracket ring are fixedly connected to form a whole that is rotatably connected to the high-speed input hollow shaft through the third bearing and the fourth bearing.

10. A reducer for a robot joint according to claim 9, characterized in that: The first bearing and the third bearing are coaxially arranged; the second bearing and the fourth bearing are coaxially arranged.

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