Axially compact joint module and joint structure

Abstract

The application provides a joint module and a joint structure which are axially compact, and the joint module comprises a harmonic assembly, a motor assembly, and a brake assembly; the harmonic assembly comprises a cross-roller bearing outer ring fixedly connected with a steel wheel, a cross-roller bearing inner ring fixedly connected with a hollow shaft, a flexspline engaged with the steel wheel, and the flexspline connected with a wave generator through a bearing; the motor assembly comprises a motor stator coupled with a motor rotor, a motor shaft fixedly connected with the motor rotor, and the engaged part of the flexspline and the steel wheel extending into the motor shaft, and a small bearing arranged between the inner circle of the motor shaft and the hollow shaft; the brake assembly comprises a brake shaft fixedly connected with the motor shaft and a brake cover plate fixedly connected with a shell, and the outer circle of the motor shaft is connected with the shell through the cooperation of a large bearing and the brake cover plate. The engaged part of the flexspline and the steel wheel extends into the motor shaft, and the small bearing and the large bearing are axially overlapped and distributed, so that the total length of the joint is reduced, and the axial compactness of the joint module is improved.

Description

Technical Field

[0001] This invention relates to the field of joint module structure design, specifically to an axially compact joint module and joint structure. Background Technology

[0002] A joint module is a highly integrated robot joint component. It typically consists of several key components, including motors (such as frameless torque motors), reducers (such as harmonic, planetary, and roller screws), encoders, and drivers. As a critical component of humanoid robots, the joint module largely determines the robot's explosive force and load-bearing capacity.

[0003] With the development of technology, higher requirements have been placed on the structural design of robots, such as the need for greater space utilization.

[0004] A Chinese patent application with publication number CN109366480A discloses a highly integrated electromechanical control robot joint module. The joint module includes a housing, a braking device, a hollow frameless motor, a harmonic reducer, a low-voltage DC driver, and corresponding PCB circuit boards. It also includes an incremental encoder for measuring the input speed of the motor and an absolute encoder for measuring the output of the harmonic reducer. All rotating parts of the joint module are coaxially arranged and designed in a hollow mode to facilitate wiring.

[0005] The existing joint module uses a configuration in which the brake, motor, and harmonic components are arranged side by side, which has the following drawbacks:

[0006] 1. The motor shaft lacks double support, resulting in insufficient rotational stability;

[0007] 2. The overall axial dimension of the joint is long, and the joint compactness is insufficient. Summary of the Invention

[0008] In view of the deficiencies in the prior art, the purpose of this invention is to provide an axially compact joint module and joint structure.

[0009] According to the present invention, an axially compact joint module includes a housing, a harmonic assembly, a motor assembly, and a brake assembly, wherein the harmonic assembly, the motor assembly, and the brake assembly are arranged sequentially along the axial direction of the housing.

[0010] The harmonic assembly includes a crossed roller bearing, a steel wheel, a flexible wheel, a wave generator, and a hollow shaft. The outer ring of the crossed roller bearing is fixedly connected to the steel wheel, the inner ring of the crossed roller bearing is fixedly connected to the hollow shaft, the flexible wheel meshes with the steel wheel, and the flexible wheel is connected to the wave generator through a bearing.

[0011] The motor assembly includes a motor stator, a motor rotor, and a motor shaft. The motor stator is coupled to the motor rotor, and the motor shaft is fixedly connected to the motor rotor. The meshing part of the flexible wheel and the steel wheel extends into the motor shaft, and a small bearing is provided between the inner circle of the motor shaft and the hollow shaft.

[0012] Preferably, the small bearing and the large bearing overlap partially or completely in the axial direction.

[0013] Preferably, a first cavity is formed on the side of the motor shaft near the harmonic assembly, and the meshing portion of the flexible wheel and the steel wheel extends into the first cavity.

[0014] Preferably, the brake assembly includes a brake shaft and a brake cover plate. The brake shaft is fixedly connected to the motor shaft, and the brake cover plate is fixedly connected to the housing. The outer circle of the motor shaft and the housing are connected by a large bearing and the brake cover plate. The outer circle of the motor shaft near the brake assembly and the motor stator form a second cavity. The inner circles of the large bearing and the brake cover plate are disposed in the second cavity, and the inner circle of the large bearing contacts the outer circle of the motor shaft.

[0015] Preferably, the outer circle of the brake cover extends out of the second recess, and the outer circle of the brake cover is abutted and fixed by a fastener fixed to the outer shell.

[0016] Preferably, the fastener includes a set screw, which can eliminate bearing clearance by applying external force before locking.

[0017] Preferably, the hollow shaft is provided with a washer or shaft retainer to limit the axial displacement of the small bearing on its outer periphery; the washer or shaft retainer is provided on the side of the small bearing away from the brake assembly.

[0018] Preferably, the brake assembly includes a brake shaft and a brake cover plate. The brake shaft is fixedly connected to the motor shaft, and the brake cover plate is fixedly connected to the housing. The outer circle of the motor shaft and the housing are connected by a large bearing and the brake cover plate. The brake assembly also includes brake pads, an armature, and an electromagnet. The electromagnet separates the armature from the brake pads or presses the brake pads onto the brake cover plate by applying magnetic force to the armature or disconnecting the magnetic force.

[0019] Preferably, the electromagnet is ring-shaped, and an encoder circuit board is fixedly mounted on the inner circle of the electromagnet; an output encoder is provided on the hollow shaft, and the output encoder is coupled to the encoder circuit board.

[0020] According to a joint structure provided by the present invention, an axially compact joint module is adopted.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. This invention extends the meshing part of the flexible wheel and the steel wheel into the motor shaft, and overlaps the flexible wheel, the steel wheel and the motor shaft in the axial dimension, which helps to improve the axial compactness of the joint module.

[0023] 2. The present invention, through the dual support structure of small and large bearings, can enhance the stability of motor shaft rotation on the one hand, and the axial overlapping distribution of the two bearings can reduce the total length of the joint, which helps to improve the axial compactness of the joint module.

[0024] 3. The present invention uses a brake cover plate as a brake component, which can rub against the brake pads to brake, and as an outer ring support for the bearing, thus functioning as a bearing seat. One part has multiple functions, eliminating the need to design a separate bearing seat, saving space and helping to improve the compactness of the structure. Attached Figure Description

[0025] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0026] Figure 1 This is a schematic diagram illustrating the overall structure of the joint module, which is the main feature of this invention.

[0027] Figure 2 This is a cross-sectional view that mainly illustrates the overall structure of the joint module in this invention.

[0028] As shown in the figure:

[0029] Harmonic component 1 Motor shaft 33

[0030] Crossed roller bearing 11, brake shaft 34

[0031] 12 steel wheels and 4 brake components

[0032] Flexible wheel 13, brake cover 41

[0033] Wave generator 14 Brake pads 42

[0034] Hollow shaft 15, armature 43

[0035] 16mm retaining ring, 44mm electromagnet

[0036] Housing 21, Large bearing 51

[0037] Set screw 22, small bearing 52

[0038] Motor assembly 3 Input encoder 61

[0039] Motor stator 31, encoder circuit board 62

[0040] Motor rotor 32, output encoder 63 Detailed Implementation

[0041] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0042] like Figure 1 and Figure 2 As shown, an axially compact joint module provided by the present invention includes a housing 21, a harmonic assembly 1, a motor assembly 3, and a brake assembly 4, wherein the harmonic assembly 1, the motor assembly 3, and the brake assembly 4 are arranged sequentially along the axial direction of the housing 21.

[0043] The harmonic assembly 1 includes a crossed roller bearing 11, a steel wheel 12, a flexible wheel 13, a wave generator 14, and a hollow shaft 15. The outer ring of the crossed roller bearing 11 is fixedly connected to the steel wheel 12, and the inner ring of the crossed roller bearing 11 is fixedly connected to the hollow shaft 15. The flexible wheel 13 meshes with the steel wheel 12, and the flexible wheel 13 is connected to the wave generator 14 via a bearing. The motor assembly 3 includes a motor stator 31, a motor rotor 32, and a motor shaft 33. The motor stator 31 is coupled to the motor rotor 32, and the motor shaft 33 is fixedly connected to the motor rotor 32. The meshing portion of the flexible wheel 13 and the steel wheel 12 extends into the motor shaft 33, and a small bearing 52 is provided between the inner circle of the motor shaft 33 and the hollow shaft 15. The brake assembly 4 includes a brake shaft 34 and a brake cover plate 41. The brake shaft 34 is fixedly connected to the motor shaft 33, and the brake cover plate 41 is fixedly connected to the housing 21. The outer circle of the motor shaft 33 and the housing 21 are connected by the cooperation of the large bearing 51 and the brake cover plate 41.

[0044] The technical solution of this application, through the design of the joint module structure, extends the meshing part of the flexible wheel 13 and the steel wheel 12 into the motor shaft 33, overlapping them in the axial dimension. Furthermore, the dual-support structure of the small bearing 52 and the large bearing 51 enhances the rotational stability of the motor shaft 33, and the axially overlapping distribution of the two bearings reduces the overall length of the joint, thereby achieving an axially compact joint module.

[0045] Specifically, the harmonic assembly 1 includes a crossed roller bearing 11, a steel wheel 12, a flexible wheel 13, a wave generator 14, and a hollow shaft 15. The outer ring of the crossed roller bearing 11 is locked to the steel wheel 12 with screws and is thus locked together with the outer casing 21 as an assembly. The inner ring of the crossed roller bearing 11 is locked to the hollow shaft 15 with screws, and rotates with the flexible wheel 13 to provide output. The structure of the harmonic assembly 1 in this application is basically the same as that of the harmonic assembly 1 in the prior art, and will not be described in detail here. It should be emphasized that the wave generator 14 of the harmonic assembly 1 in this application is connected to the motor shaft 33 using an interference fit, eliminating the need for screws and ensuring the concentricity between the motor shaft 33 and the wave generator 14. The meshing portion of the flexible wheel 13 and the steel wheel 12 extends into the motor shaft 33, overlapping in the axial dimension, thus optimizing the axial compactness of the joint module.

[0046] More specifically, a first cavity is formed on the side of the motor shaft 33 near the harmonic assembly 1, and the meshing portion of the flexible wheel 13 and the steel wheel 12 extends into the first cavity. Further, the first cavity is shaped like a "pocket," and the flexible wheel 13 of the harmonic assembly 1 needs a certain length to ensure strength. The meshing portion of the flexible wheel 13 and the steel wheel 12 is extended into the motor shaft 33, overlapping in the axial dimension. A second cavity is formed on the outer circle of the motor shaft 33 near the brake assembly 4, where it mates with the motor stator 31. The inner circles of the large bearing 51 and the brake cover plate 41 are located within the second cavity, with the inner circle of the large bearing 51 contacting the outer circle of the motor shaft 33. The outer circle of the brake cover plate 41 extends out of the second cavity and is fixed by a fastener fixed to the housing 21. The fastener includes a set screw 22, which can eliminate bearing clearance by applying external force before locking.

[0047] The motor rotor 32 is bonded to the outer ring of the motor shaft 33 using retaining adhesive. The motor stator 31 is bonded to the joint housing 21 using retaining adhesive. The inner circle of the motor shaft 33 is supported by a small bearing 52, and the outer circle is supported by a large bearing 51. This double-support structure enhances the rotational stability of the motor shaft 33, and the axial overlap of the two bearings reduces the overall length of the joint. The motor shaft 33 is connected to the brake shaft 34 with screws. The brake shaft 34 also serves as the mounting base for the input encoder 61, which rotates with the motor shaft 33 to provide position, speed, and other input signals.

[0048] More specifically, the brake assembly 4 also includes a brake pad 42, an armature 43, and an electromagnet 44; the electromagnet 44 separates the armature 43 from the brake pad 42 or presses the brake pad 42 onto the brake cover plate 41 by applying magnetic force to the armature 43 or disconnecting the magnetic force. The electromagnet 44 is ring-shaped, and an encoder circuit board 62 is fixedly mounted on the inner circle of the electromagnet 44; an output encoder 63 is provided on the hollow shaft 15, and the output encoder 63 is coupled to the encoder circuit board 62.

[0049] In one feasible implementation: the brake assembly 4 mainly consists of a brake cover plate 41, brake pads 42, an armature 43, and an electromagnet 44. The brake cover plate 41 also serves to support the outer ring of the large bearing 51. The outer ring of the brake cover plate 41 has evenly distributed platforms machined on it, which are locked in place by the set screws 22 on the housing 21. Before locking, external force can be applied to eliminate bearing clearance. The inner circle of the electromagnet 44 has three bosses and threaded holes, which can lock the encoder circuit board 62. The output encoder 63 is fitted onto the hollow shaft 15 with an interference fit, providing position, speed, and other signals at the output end.

[0050] In a preferred embodiment, the small bearing 52 and the large bearing 51 partially or completely overlap in the axial direction.

[0051] In a preferred embodiment, a washer or shaft retainer 16 is provided on the outer periphery of the hollow shaft 15 to restrict the axial displacement of the small bearing 52; the washer or shaft retainer 16 is provided on the side of the small bearing 52 away from the brake assembly 4.

[0052] It should be noted that the harmonic component 1 is inserted into the motor component 3, the support bearings of the motor shaft 33 are distributed inside and outside, and the brake component 4 is fixed to the housing 21 using set screw 22. This design arranges the parts to overlap as much as possible in the axial dimension, minimizing the axial dimension of the joint and the overall weight of the joint, and has significant advantages such as high weight reduction and high energy density.

[0053] The present invention also provides a joint structure employing an axially compact joint module, which can be implemented by performing the process steps of an axially compact joint module method.

[0054] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0055] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An axially compact joint module, characterized in that, It includes a housing (21), a harmonic assembly (1), a motor assembly (3) and a brake assembly (4), wherein the harmonic assembly (1), the motor assembly (3) and the brake assembly (4) are arranged sequentially along the axial direction of the housing (21); The harmonic assembly (1) includes a crossed roller bearing (11), a steel wheel (12), a flexible wheel (13), a wave generator (14), and a hollow shaft (15). The outer ring of the crossed roller bearing (11) is fixedly connected to the steel wheel (12), and the inner ring of the crossed roller bearing (11) is fixedly connected to the hollow shaft (15). The flexible wheel (13) meshes with the steel wheel (12), and the flexible wheel (13) is connected to the wave generator (14) through a bearing. The motor assembly (3) includes a motor stator (31), a motor rotor (32), and a motor shaft (33). The motor stator (31) is coupled to the motor rotor (32), and the motor shaft (33) is fixedly connected to the motor rotor (32). The meshing part of the flexible wheel (13) and the steel wheel (12) extends into the motor shaft (33). A small bearing (52) is provided between the inner circle of the motor shaft (33) and the hollow shaft (15). The small bearing (52) and the large bearing (51) overlap partially or completely in the axial direction; The brake assembly (4) includes a brake shaft (34) and a brake cover plate (41). The brake shaft (34) is fixedly connected to the motor shaft (33), and the brake cover plate (41) is fixedly connected to the outer shell (21). The outer circle of the motor shaft (33) and the outer shell (21) are connected by a large bearing (51) and the brake cover plate (41). The outer circle of the motor shaft (33) near the brake assembly (4) and the motor stator (31) form a second cavity; The inner circles of the large bearing (51) and the brake cover plate (41) are arranged in the second cavity, and the inner circle of the large bearing (51) is in contact with the outer circle of the motor shaft (33). The outer circle of the brake cover (41) extends out of the second concave cavity, and the outer circle of the brake cover (41) is abutted and fixed by a fastener fixed on the outer shell (21).

2. The axially compact joint module as described in claim 1, characterized in that, The motor shaft (33) has a first cavity formed on the side near the harmonic assembly (1), and the meshing part of the flexible wheel (13) and the steel wheel (12) extends into the first cavity.

3. The axially compact joint module as described in claim 1, characterized in that, The fastener includes a set screw (22), which can eliminate bearing clearance by applying external force before locking.

4. The axially compact joint module as described in claim 1, characterized in that, The hollow shaft (15) is provided with a washer or shaft retainer (16) on its outer periphery to restrict the axial displacement of the small bearing (52). The washer or shaft retainer (16) is located on the side of the small bearing (52) away from the brake assembly (4).

5. The axially compact joint module as described in claim 1, characterized in that, The brake assembly (4) includes a brake shaft (34) and a brake cover plate (41). The brake shaft (34) is fixedly connected to the motor shaft (33), and the brake cover plate (41) is fixedly connected to the outer shell (21). The outer circle of the motor shaft (33) and the outer shell (21) are connected by a large bearing (51) and the brake cover plate (41). The brake assembly (4) also includes brake pads (42), armature (43) and electromagnet (44). The electromagnet (44) separates the armature (43) from the brake pad (42) or presses the brake pad (42) onto the brake cover plate (41) by applying magnetic force to the armature (43) or disconnecting the magnetic force.

6. The axially compact joint module as described in claim 5, characterized in that, The electromagnet (44) is ring-shaped, and an encoder circuit board (62) is fixedly installed on the inner circle of the electromagnet (44). An output encoder (63) is provided on the hollow shaft (15), and the output encoder (63) is coupled to the encoder circuit board (62).

7. A joint structure, characterized in that, The axially compact joint module described in claim 1 is adopted.

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