Joint module

Abstract

The application provides a joint module, comprising an axial flux motor, a speed reduction transmission module and a sensing device arranged integrally along the same rotation axis; the speed reduction transmission module is embedded in the internal radial position of the axial flux motor, and the sensing device is arranged on the top or bottom of the axial flux motor; the axial flux motor comprises a stator assembly and a rotatable rotor assembly; the input end of the speed reduction transmission module is in transmission connection with the rotor assembly; the sensing device is connected with the output shaft of the speed reduction transmission module, and is used for collecting the actual rotation position and speed information of the output end in real time, so as to realize full closed loop control of the output end. The axial flux motor, the speed reduction transmission module and the sensing device are coaxially nested and integrated along the same rotation axis, the central installation space in the axial flux motor is fully utilized, the speed reduction transmission module is embedded in the internal space, space multiplexing is effectively realized, and the sensing device is arranged on the top or bottom of the motor, so that the axial structure is not additionally lengthened.

Description

A joint module Technical Field

[0001] This application relates to the field of industrial automation, and more specifically, to a joint module. Background Technology

[0002] In the fields of robotics, precision servo systems, and automation equipment, joint modules, as core actuators, typically consist of a motor, a reducer, and a position feedback device. Traditional joint modules often employ a split design, where the servo motor is connected to a harmonic reducer or planetary reducer via a coupling, and then an encoder is used to achieve closed-loop control. However, this structure has the following prominent problems:

[0003] The structure is scattered and the size is large: the motor, reducer and encoder are installed independently, resulting in a long axial dimension and a large radial space occupation, which makes it difficult to meet the requirements of humanoid robots and collaborative robots for lightweight and compact layout.

[0004] In addition, the following problems exist:

[0005] The transmission chain is complex and inefficient: it requires the use of additional couplings or belts to transmit power, which introduces elastic deformation and mechanical backlash, affecting dynamic response speed and positioning accuracy.

[0006] Inaccurate feedback signals: Most systems only install encoders (feedforward measurement) at the motor end, which cannot detect backlash, wear or elastic deformation inside the reducer, causing the control system to misjudge the actual output position, resulting in trajectory deviation or even oscillation.

[0007] Poor heat dissipation: High power density motors generate a lot of heat when running, but traditional casings have a small surface area and a long heat conduction path, which can easily cause excessive temperature rise and limit continuous output capacity.

[0008] Complex assembly and low reliability: The splicing of multiple parts leads to the accumulation of assembly errors, difficulty in sealing, easy leakage of grease, and significant performance degradation after long-term operation.

[0009] Therefore, there is an urgent need for a new type of joint module with highly integrated structure, efficient transmission, precise feedback and good thermal management capabilities to solve the above-mentioned technical bottlenecks. Summary of the Invention

[0010] In view of one of the defects in the prior art, the purpose of this application is to provide a joint module with an embedded cycloidal pinwheel reducer axial magnetic flux.

[0011] A first aspect of this application provides a joint module, including an axial flux motor, a reduction transmission module, and a sensing device integrated along the same rotation axis; the reduction transmission module is embedded in the internal radial position of the axial flux motor, and the sensing device is disposed at the top or bottom of the axial flux motor;

[0012] The axial flux motor includes a stator assembly and a rotatable rotor assembly;

[0013] The input end of the speed reduction transmission module is connected to the rotor assembly in a transmission connection.

[0014] The sensing device is connected to the output shaft of the speed reduction transmission module and is used to collect the actual rotational position and speed information of the output end in real time, so as to realize the full closed-loop control of the output end.

[0015] Optionally, the axial flux motor adopts a dual-stator single-rotor structure, including an upper stator winding and a lower stator winding arranged coaxially, and a rotor assembly located between the two; the rotor assembly forms axial air gaps between itself and the upper stator winding, and between itself and the lower stator winding, to form a dual-air gap magnetic field path.

[0016] Optionally, the speed reduction transmission module is a cycloidal pinwheel reducer, including an eccentric shaft, a fixed housing, a cycloidal wheel, and an output shaft;

[0017] One end of the eccentric shaft is connected to the output end of the axial flux motor to receive torque, and the other end is the eccentric section for mounting the cycloidal wheel;

[0018] The inner wall of the fixed shell is provided with a plurality of first components evenly distributed in the circumferential direction, and the cycloidal wheel is provided with a corresponding second component; the first component and the second component slide or roll in cooperation.

[0019] When the eccentric shaft drives the cycloidal wheel to make eccentric motion, the second component rolls or slides relative to the first component, causing the cycloidal wheel to rotate in the opposite direction while revolving around the eccentric shaft, thereby realizing speed reduction transmission.

[0020] The output shaft is connected to the cycloidal wheel for transmission, and outputs decelerated rotational motion.

[0021] Optionally, the number of the second component is one less than the number of the first component, and the reduction ratio γ satisfies the formula:

[0022] γ = N2 / (N1 - N2)

[0023] N1 represents the number of the first component, and N2 represents the number of the second component.

[0024] Optionally, the sensing device includes a sensing rotor and a measuring stator, the sensing rotor being connected to the reduction transmission module; the measuring stator is fixed, and the position and speed information of the sensing rotor are collected.

[0025] Optionally, it also includes a rotor force transmission sleeve;

[0026] The rotor force transmission sleeve is fixed in the inner hole of the rotor assembly and rotates synchronously with the rotor assembly;

[0027] The input end of the speed reduction transmission module transmits torque to the rotor assembly through the rotor force transmission sleeve, thereby establishing a transmission connection.

[0028] Optionally, the rotor force transmission sleeve is connected to the input end of the speed reduction transmission module through a double-flat structure, and the sensing device is connected to the output end of the speed reduction transmission module through a double-flat structure.

[0029] Optionally, the rotor transmission sleeve is equipped with an inclined air duct to achieve active cooling by self-fanning during rotation; the stator assembly is equipped with a VC heat dissipation plate to dissipate heat from the motor.

[0030] Optionally, it also includes a housing that encloses the entire joint module and has multiple stepped rings on its exterior to increase the heat dissipation surface area.

[0031] Optionally, the internal cavity of the speed reduction transmission module is filled with grease and is equipped with a sealing ring to prevent grease leakage and the intrusion of external contaminants.

[0032] This application provides a joint module with an embedded cycloidal pinwheel reducer axial flux, which coaxially integrates the axial flux motor, the reduction transmission module, and the sensing device along the same rotation axis. This fully utilizes the central mounting space inside the axial flux motor, embedding the reduction transmission module within it, effectively achieving space reuse. Simultaneously, the sensing device is positioned at the top or bottom of the motor, avoiding the need for additional axial structural extension. Compared to traditional split-series layouts, this embodiment significantly reduces the overall axial dimension and radial space occupied, improves power density and structural compactness, and solves the technical challenges of large joint module size and difficulty in adapting to lightweight robot systems in existing technologies. It is particularly suitable for applications with extremely high requirements for space layout and weight control, such as humanoid robots and collaborative robotic arms.

[0033] Other technical effects resulting from the additional features will be further illustrated in the corresponding embodiments. Attached Figure Description

[0034] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0035] Figure 1 is a partial cross-sectional perspective view of a joint module according to an exemplary embodiment;

[0036] Figure 2 is a global cross-sectional plan view of a joint module according to an exemplary embodiment;

[0037] Figure 3 is an exploded perspective view of a joint module according to an exemplary embodiment;

[0038] Figure 4 is a partial cross-sectional perspective assembly view of an axial flux motor according to an exemplary embodiment;

[0039] Figure 5 is an exploded perspective view of an axial flux motor according to an exemplary embodiment;

[0040] Figure 6 is a partial cross-sectional perspective assembly view of an embedded cycloidal pinwheel reducer according to an exemplary embodiment;

[0041] Figure 7 is an exploded perspective view of an embedded cycloidal pinwheel reducer according to an exemplary embodiment;

[0042] Figure 8 is a schematic diagram of the rotor force transmission sleeve according to an exemplary embodiment;

[0043] Figure 9 is a schematic diagram of the connection structure between the rotor force transmission sleeve and the eccentric shaft, the encoder shaft at the reducer end and the rotor core shaft inside the encoder, according to an exemplary embodiment. In the figure: a is a schematic diagram of the double flat structure of the rotor force transmission sleeve; b is a schematic diagram of the connection between the rotor force transmission sleeve and the eccentric shaft; c is a schematic diagram of the double flat structure of the bearing inside the force transmission sleeve; d is a schematic diagram of the double flat structure of the encoder shaft at the reducer end.

[0044] In the diagram, 100 is the reduction transmission module, 200 is the axial flux motor, 300 is the sensing device, and 400 is the rotor force transmission sleeve.

[0045] 101-Stepped bearing, 102-Eccentric shaft, 103-Output shaft, 104-Roller pin, 105-First pin retaining shell, 106-Pin, 107-First cycloidal wheel, 108-Second cycloidal wheel, 109-Second pin retaining shell;

[0046] 201-Rotor assembly, 202-Stator assembly, 2021-Upper stator winding, 2022-Lower stator winding, 203-VC heat spreader;

[0047] 301-Encoder outer rotor plate, 302-Rotor support bearing, 303-Bearing retaining ring, 304-Encoder stator plate bracket, 305-Encoder inner rotor plate, 306-Encoder stator plate, 307-Encoder inner rotor spindle, 308-Reducer end encoder shaft, 309-Encoder inner rotor bearing;

[0048] 401 - First step hole, 402 - Second step hole, 403 - Third step hole, 404 - Third step shaft, 405 - Air duct;

[0049] 501 - Rear cover, 502 - Drive board, 503 - Outer shell;

[0050] 10-Double flattened structure. Detailed Implementation

[0051] The present application 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 application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all fall within the protection scope of the present application. Parts not described in detail in the following embodiments can be implemented using existing technology.

[0052] Currently, mature joint modules on the market suffer from problems such as fragmented structure and large size. The motor, reducer, and encoder are installed independently, resulting in excessively long axial dimensions and large radial space occupation, making it difficult to meet the requirements of humanoid robots and collaborative robots for lightweight and compact layout. To address these issues, this application provides a joint module with an embedded cycloidal pinwheel reducer axial magnetic flux to solve the aforementioned problems.

[0053] As shown in Figures 1 and 2, in one specific embodiment, a joint module includes an axial flux motor 200, a reduction transmission module 100, and a sensing device 300 integrated along the same rotation axis; the reduction transmission module 100 is embedded in the internal radial position of the axial flux motor 200, and the sensing device 300 is disposed at the top or bottom of the axial flux motor 200.

[0054] The axial flux motor 200 includes a stator assembly 202 and a rotatable rotor assembly 201;

[0055] The input end of the speed reduction transmission module 100 is connected to the rotor assembly 201 for transmission.

[0056] The sensor 300 is connected to the output shaft 103 of the speed reduction transmission module 100 to collect the actual rotational position and speed information of the output end in real time, so as to realize the full closed-loop control of the output end.

[0057] The above embodiments integrate the axial flux motor, reduction gear transmission module, and sensing device coaxially along the same axis of rotation, making full use of the central mounting space inside the axial flux motor to embed the reduction gear transmission module, effectively achieving space reuse. Simultaneously, the sensing device is placed at the top or bottom of the motor, avoiding the need for additional axial structural extension. Compared to traditional split-series layouts, the above embodiments significantly reduce the overall axial dimension and radial space occupied, improve power density and structural compactness, and solve the technical challenges of large joint module size and difficulty in adapting to lightweight robot systems in existing technologies. They are particularly suitable for applications with extremely high requirements for space layout and weight control, such as humanoid robots and collaborative robotic arms.

[0058] To further improve the power density of the axial flux motor, in some specific embodiments of this application, as shown in Figures 3-7, the axial flux motor 200 adopts a double-stator clamped single-rotor structure, including an upper stator winding 2021 and a lower stator winding 2022 arranged coaxially, with their magnetic field direction distributed along the axial direction; the rotor assembly 201 is located between the two, and contactless rotational transmission is achieved through an air gap. This structure can form a double air gap working surface, effectively improving the electromagnetic torque density and power density.

[0059] The above embodiment adopts a coaxial structure with a double stator clamping a single rotor, that is, the upper stator winding and the lower stator winding are located on both sides of the rotor assembly, forming a double air gap magnetic field, which effectively increases the electromagnetic torque output capability. Under the same volume, the magnetic circuit is shorter and the iron core utilization rate is higher, which significantly improves the power density and torque density of the motor, while maintaining a low moment of inertia, meeting the requirements of high-performance joint modules for high dynamic response and compact layout.

[0060] There are many types of speed reduction devices. In order to adapt to the internal radial space of the axial flux motor of this application, in some specific embodiments of this application, as shown in Figure 3, the speed reduction transmission module is a cycloidal pinwheel reducer, including an eccentric shaft 102, a fixed housing, a cycloidal wheel and an output shaft 103.

[0061] One end of the eccentric shaft 102 is driven to the output end of the axial flux motor 200 to receive torque, and the other end is an eccentric section for mounting the cycloidal wheel; the inner wall of the fixed shell is provided with a plurality of first components evenly distributed circumferentially, and the cycloidal wheel is provided with a corresponding second component; the first component and the second component slide or roll in cooperation, and when the eccentric shaft 102 drives the cycloidal wheel to make eccentric motion, the second component rolls or slides relative to the first component, so that the cycloidal wheel generates a reverse rotation while revolving around the eccentric shaft 102, thereby realizing deceleration transmission; the output shaft 103 is driven to the cycloidal wheel and outputs the decelerated rotational motion.

[0062] Specifically, the first component is a mechanical element fixed circumferentially to the inner wall of the fixed housing, including but not limited to: pin teeth, fixing pins, or roller assemblies composed of needle rollers and cages; the second component is a corresponding mating structure set on the cycloidal wheel and moving with the cycloidal wheel, including but not limited to pin holes, circular grooves, or precision circular arc rolling tracks that pass through the cycloidal wheel.

[0063] Preferably, the first component and the second component form a rolling fit. For example, when the first component uses a pin 106 and the second component uses a matching cycloidal wheel external tooth, or when the first component uses a needle roller assembly with a cage and the second component is a matching arc rolling track, the two form a meshing pair similar to a rolling bearing. Driven by the eccentric shaft 102, it achieves a highly efficient and low-wear differential reduction transmission, which has the advantages of multiple teeth bearing loads simultaneously, zero backlash, and high rigidity.

[0064] In another embodiment, the first component can be a fixed pin, and the second component can be a smooth pin hole or an arc groove formed on the cycloidal wheel, forming a sliding fit pair. In this case, during the eccentric motion of the cycloidal wheel, its pin hole is fitted onto the outer circle of the pin and undergoes continuous relative sliding, thereby achieving the deceleration function. The structure is simple, the manufacturing cost is low, and it is an economical product suitable for specific working conditions.

[0065] The above embodiment uses a cycloidal pinwheel reducer as the reduction transmission module. Its compact structure and small radial dimension allow it to be effectively embedded in the central annular space of the axial flux motor, making full use of the limited installation area. The cycloidal wheel is driven by an eccentric shaft to roll eccentrically within the fixed housing, and differential reduction is achieved by the cooperation between the first and second components. It features simultaneous meshing of multiple teeth, zero backlash, and high rigidity, resulting in strong load-bearing capacity and smooth transmission. Combined with its large speed ratio characteristics, it significantly improves the output torque density without increasing the axial length, meeting the integration requirements of robot joints for high power density, high precision, and high reliability.

[0066] It should be understood that although the embodiments of this application take the cycloidal pinwheel reducer as the main example, without departing from the concept of the present invention, the reduction transmission module can also be replaced by other types of reduction devices such as harmonic reducers or RV reducers. As long as it can be integrated into the internal space of the axial flux motor and connected to the output shaft for transmission, it falls within the protection scope of this application.

[0067] To achieve high-ratio, high-precision speed reduction transmission, this application employs a planetary meshing structure based on the principle of tooth number difference in some embodiments. Specifically, as shown in Figure 3, the speed reduction transmission module 100 is a cycloidal pinwheel reducer. Its fixed housing inner wall is provided with multiple first components, such as pins 106 or needle teeth, evenly distributed circumferentially. The cycloidal wheel is provided with second components, such as external cycloidal teeth or rollers, that mesh with it. The number of second components... The number of the first component One less, that is, satisfying:

[0068]

[0069] When the eccentric shaft 102 drives the cycloidal wheel to perform eccentric revolution around the first component, due to the difference in quantity, the second component periodically rolls and meshes with the first component, causing the cycloidal wheel to rotate in the opposite direction while completing one revolution. This allows for differential speed reduction output.

[0070] The reduction ratio of this structure Satisfy the following formula: N1 represents the number of the first component, and N2 represents the number of the second component.

[0071] For example, if the number of pins 106 in the first component is 41 and the number of cycloidal teeth in the second component is 40, then the reduction ratio is: γ=40:1.

[0072] The above embodiments not only achieve single-stage high speed ratio reduction, but also have advantages such as zero backlash, high rigidity, and smooth transmission, making them particularly suitable for robot joint applications with high requirements for output accuracy and load-bearing capacity.

[0073] To achieve high-precision measurement of the motion state of the joint module output end, this application includes a sensing device 300 in some specific embodiments for real-time acquisition of the actual position and speed information of the output shaft 103 of the reduction transmission module 100. The sensing device 300 includes a sensing rotor and a measuring stator.

[0074] The sensing rotor is connected to the output shaft 103 of the reduction transmission module 100 and can rotate synchronously with the output shaft 103. In this embodiment, the sensing rotor is fixedly connected to the output shaft 103 through the encoder shaft at the reducer end to ensure that there is no relative sliding between the two. The measuring stator is fixed on a static structure, such as the back cover 501 or the bearing retaining ring 303, and does not participate in the rotation.

[0075] When the output shaft 103 drives the sensing rotor to rotate, the measuring stator detects its position change relative to itself based on magnetic induction or photoelectric principles, thereby obtaining signals such as angular displacement and rotational speed at the output end. This signal is processed and fed back to the drive control system to achieve full closed-loop control of the output end.

[0076] The above embodiments enable direct measurement at the output end, eliminate the influence of backlash and elastic deformation, improve control accuracy and response stability, and support high-resolution full closed-loop control.

[0077] It should be understood that the sensing device can be flexibly configured according to actual application requirements. Its type is not limited to a specific form; various high-precision position sensors such as photoelectric encoders, magnetic encoders, or resolvers can be selected, coaxially mounted on the output shaft extension, with the signal line led out through the stator center through-hole to avoid interference with the motor's magnetic field. When using a photoelectric encoder, it is suitable for precision control in high-resolution, clean environments; when the working environment contains dust, oil, or strong vibration, a magnetic encoder or resolver structure with strong anti-interference capabilities can be selected to improve operational reliability.

[0078] In some specific embodiments, as shown in Figures 3-5, the sensing device 300 is installed at the bottom of the entire module. In order to achieve the integrity of the module, this embodiment also includes a back cover 501, a drive board 502, and a housing 503.

[0079] Specifically, the rear cover 501 is located at the very end of the entire joint module, serving to enclose the overall structure and act as a mounting base. It is equipped with power input / output connectors and a communication interface for external electrical connections. Several heat dissipation fins are located directly above the power components to assist in heat dissipation for the drive board 502.

[0080] The drive board 502 is located above the rear cover 501 and is fixed in a specific position by three studs on the bearing retaining ring 303 to ensure stable circuit operation.

[0081] The outer shell 503 covers the entire module body, and its outer ring has multiple stepped ring structures to increase the surface area and enhance the natural convection and radiation heat dissipation capabilities.

[0082] Furthermore, the encoder includes an outer rotor plate 301, a rotor support bearing 302, a bearing retaining ring 303, an encoder stator plate bracket 304, an inner rotor plate 305, an encoder stator plate 306, an inner rotor spindle 307, and an encoder shaft 308 at the reducer end.

[0083] The encoder assembly structure is as follows: The encoder is set above the drive board 502, with its stator part remaining stationary and its rotor part rotating synchronously with the output end.

[0084] The encoder stator plate 306 is fixed by the encoder stator plate bracket 304;

[0085] The outer ring of the encoder stator plate bracket 304 is fixed to the bearing retaining ring 303 to form a stable static reference.

[0086] Ensure that there is a uniform air gap of 0.5–0.7 mm between the encoder stator plate 306 and the encoder inner rotor plate 305 and the encoder outer rotor plate 301, and that they are strictly concentric, so as to ensure the stability of signal acquisition.

[0087] The encoder rotor section consists of the following components:

[0088] The encoder inner rotor core 307 has a stepped structure, and its outer ring is equipped with an encoder inner rotor bearing 309, which is used to support the rotational motion and ensure concentricity.

[0089] The encoder inner rotor plate 305 is fixed to the encoder inner rotor spindle 307 by interference fit or glue bonding.

[0090] The encoder's inner rotor spindle 307 has a double-flat inner hole at its front end, which coaxially inserts into the double-flat shaft end at the front end of the encoder shaft 308 at the reducer end. The double-flat inner hole and the double-flat shaft end constitute a double-flat structure 10. The double-flat structure 10 refers to two planes symmetrically arranged circumferentially at the end or inside the hole of a shaft component, forming a non-circular cross-section connection interface. This structure includes two mating forms: a double-plane shaft segment: located at the end of the shaft, its cross-section is circular except for two symmetrical sectors, forming two parallel planes; and a double-plane inner hole: located in a sleeve or connector, its inner hole has two matching planar areas for insertion mating with the double-plane shaft segment.

[0091] The rear end has screw holes, and the two are locked together by screws to form a rigid connection, ensuring that the acquired output speed and angle information is stable and reliable over a long period of time.

[0092] In the above embodiments, the sensing device is placed at the bottom of the module, and the back cover, drive board and shell are integrated to achieve electrical connection, heat dissipation and structural enclosure in one, thereby improving system integrity and environmental adaptability.

[0093] To address the problem in existing technologies where additional couplings or belts are used to transmit power, introducing elastic deformation and mechanical clearance, which affects dynamic response speed and positioning accuracy, in some specific embodiments of this application, a rotor force transmission sleeve 400 is provided as shown in Figures 3-5. The rotor force transmission sleeve 400 is fixedly connected to the rotor assembly 201 and is located on its inner or outer circumference.

[0094] The input end of the speed reduction transmission module 100 transmits torque to the rotor assembly 201 through the rotor force transmission sleeve 400, thereby establishing a transmission connection.

[0095] In the above embodiments of this application, the rotor assembly and the reducer are directly connected by a rotor force transmission sleeve, eliminating the need for a coupling or belt, eliminating mechanical backlash and elastic deformation, and improving transmission rigidity and dynamic response accuracy.

[0096] The rotor transmission sleeve 400 is the core transmission component of this application, used to efficiently transmit the power of the axial flux motor 200 to the reducer. Furthermore, in some specific embodiments of this application, Figures 3-8 provide a detailed and complete optimized structural design of the rotor transmission sleeve 400. Specifically:

[0097] The rotor force transmission sleeve 400 has a bowl-shaped structure. Its maximum diameter is tightly connected to the inner hole of the rotor assembly 201. It is located inside the rotor assembly 201 and is fixed coaxially with it. It is driven by the rotor assembly 201 to rotate synchronously.

[0098] It has multiple coaxial nested stepped holes inside:

[0099] First step hole 401: The inner ring is hollow, allowing the encoder shaft 308 at the reducer end to pass through; the outer ring is provided with double flat inner holes, which are used to tightly fit with the double flat shaft section at the lower end of the eccentric shaft 102 to realize torque transmission;

[0100] Second step hole 402: Used to fix the encoder outer rotor plate 301, which can be achieved by interference fit or glue bonding;

[0101] Third step shaft 404: Located below rotor force transmission sleeve 400, corresponding to third step hole 403, and rotor support bearing 302 is installed on it;

[0102] The outer ring of the rotor support bearing 302 is fixed to the inner hole of the lower stator winding 2022, and is limited by the bearing retaining ring 303 to ensure that it is in a fixed position.

[0103] In the embodiments described above, the rotor force transmission sleeve integrates torque transmission and bearing support, and the multi-stage stepped structure achieves component integration, thereby enhancing the system's compactness and operational stability.

[0104] In addition to using the rotor force transmission sleeve 400 described above, in some specific embodiments of this application, the rotor force transmission sleeve 400 is connected to the input end of the speed reduction transmission module 100 through a double flat structure 10, and the sensing device 300 is connected to the output end of the speed reduction transmission module 100 through a double flat structure 10.

[0105] Specifically, as shown in Figure 9, the double-flat structure 10 refers to a connection interface formed by two symmetrically arranged planes along the circumference at the end or within the hole of a shaft component, creating a non-circular cross-section. This structure includes two mating forms:

[0106] Double-plane shaft segment: Located at the end of the shaft, its cross-section is circular, removing two symmetrical sectors to form two parallel planes;

[0107] Double-plane inner hole: Located in a sleeve or connector, its inner hole has two matching planar areas for insertion and mating with a double-plane shaft segment.

[0108] In this embodiment, the double-flat structure 10 is applied in two key locations. First, it connects the rotor transmission sleeve 400 to the input end of the reduction transmission module 100. Specifically, the outer ring of the rotor transmission sleeve 400 has a double-flat stepped hole, and the lower end of the eccentric shaft 102 has a corresponding double-flat shaft section. After insertion, they are fixed by interference fit or end locking. This allows for direct torque transmission from the rotor transmission sleeve 400 to the eccentric shaft 102 without the need for keys, pins, or splines. Second, it connects the sensing device 300 to the output end of the reduction transmission module 100. Specifically, the front end of the encoder shaft 308 at the reducer end has a double-flat shaft end, and the inner rotor core 307 of the encoder has a corresponding double-flat inner hole. After insertion, they are locked with screws to form a rigid connection. This ensures that the rotational motion of the output shaft 103 is transmitted to the sensing rotor without lag, improving feedback accuracy.

[0109] The above embodiments employ a double-flat structure, which avoids the use of additional components for connection, eliminates mechanical backlash and elastic deformation, and improves transmission rigidity and dynamic response accuracy.

[0110] Based on the preferred structure of the rotor force transmission sleeve and the preferred structure of the encoder described above, some specific embodiments of this application also provide a preferred cycloidal pinwheel reducer structure, as shown in Figures 6 and 7. Specifically:

[0111] A second pin fixing shell 109 is set at a certain distance above the rotor force transmission sleeve 400, and together with the first pin fixing shell 105, they form the fixing frame of the reducer.

[0112] The outer ring of the second pin fixing shell 109 is provided with several fixing holes, which are connected to the threaded through holes on the first pin fixing shell 105 to seal and enclose the first cycloidal wheel 107 and the second cycloidal wheel 108 inside; both pin fixing shells are provided with stepped holes at corresponding positions for installing a ring of pins 106 to ensure accurate positioning and vertical axis.

[0113] The eccentric shaft 102 passes through two pin fixing shells, and its lower end is connected to the rotor force transmission sleeve 400 through the double flat structure 10 to receive torque; the eccentric shaft 102 has two layers of eccentric stepped shaft sections with a phase difference of 180°, and a stepped bearing 101 is installed on the outer ring of each section, and the outer rings of the first cycloidal wheel 107 and the second cycloidal wheel 108 are fixed respectively.

[0114] The outer rings of the two cycloidal wheels are toothed, with the teeth staggered by 180° to improve meshing continuity and avoid torque fluctuations. The number of teeth on the cycloidal wheels is one less than the number of pins, satisfying the "one-tooth difference" reduction principle. The reduction ratio formula is... ,in The number of teeth on the cycloidal wheel. This refers to the number of pins.

[0115] The internal cavity of the reducer is pre-filled with grease, and sealing rings are installed at the following locations:

[0116] Between the first pin fixing shell 105 and the second pin fixing shell 109;

[0117] The mating part between the eccentric shaft 102 and the two pins fixing the housing; to prevent grease leakage and external contaminant intrusion, achieving lifelong maintenance-free operation.

[0118] Based on the above structure, the output shaft 103 and the power transmission are specifically as follows:

[0119] The upper part of the eccentric shaft 102 is also provided with two stepped bearings, the outer ring of which fixes the output shaft 103; the output shaft 103 is provided with four stepped holes, through which the roller pin 104 passes and is locked by the upper screw; the roller pin 104 passes through the corresponding through holes on the first cycloidal wheel 107 and the second cycloidal wheel 108, transmitting the deceleration motion of the cycloidal wheel to the output shaft 103 to complete the power output.

[0120] The encoder shaft 308 at the reducer end passes through the output shaft 103, the eccentric shaft 102 and the rotor force transmission sleeve 400 from top to bottom. Its upper end is provided with a threaded hole and a pin, which is firmly fixed to the output shaft 103. It reflects the actual output status in real time and realizes closed-loop control at the end.

[0121] The above embodiments achieve sealed installation of the cycloidal wheel through a split pin fixing shell, and the 180° staggered tooth arrangement of the double cycloidal wheels improves meshing continuity and dynamic balance; the built-in lubrication and multiple sealing ring design achieve maintenance-free operation; the direct connection structure between the output shaft and the encoder shaft ensures the accuracy of the end closed-loop control.

[0122] In view of the problem that poor heat dissipation capacity in the prior art leads to excessive motor temperature rise and limits continuous output performance, this application integrates a composite heat dissipation structure of active cooling and efficient heat conduction in some specific embodiments.

[0123] Specifically, as shown in Figures 3-5, the inner ring of the rotor transmission sleeve 400 is provided with several inclined air ducts 405. The air ducts 405 are at an angle of 10° to 15° with the axis. When the rotor rotates at high speed, it generates forced airflow, forming a self-fan effect, realizing internal air circulation, and achieving active cooling effect.

[0124] Meanwhile, the rotor assembly 201 of the axial flux motor 200 is located between the upper stator winding 2021 and the lower stator winding 2022, and maintains a uniform air gap on its upper and lower surfaces to ensure stable electromagnetic performance. A VC heat spreader 203 is provided around the outer ring of the upper stator winding 2021 and the lower stator winding 2022. This VC heat spreader 203 is made of a highly thermally conductive material, including graphene, silver paste gel, or copper-based composite materials, which can quickly absorb the heat generated during motor operation and transfer the heat to the outer casing 503 through thermal conduction.

[0125] Multiple stepped ring structures are provided on the outer periphery of the housing 503 to increase the surface area and enhance the natural convection and radiation heat dissipation capacity; the upper stator winding 2021 and the lower stator winding 2022 are tightly fixed to the housing 503 by means of tight fit, glue bonding, slot or pin 106, etc., to ensure reliable thermal contact and form a low thermal resistance heat dissipation path from heat source to external environment.

[0126] The above structure significantly improves overall heat dissipation efficiency through a three-level synergistic mechanism of internal active airflow, intermediate temperature diffusion, and external expanded heat dissipation, effectively reducing operating temperature rise and ensuring continuous and stable output of the motor under high load conditions.

[0127] To address the lubrication failure and performance degradation issues caused by grease leakage in traditional joint modules, this application, in some specific embodiments, pre-fills the internal cavity of the reduction transmission module 100 with long-lasting grease and installs sealing rings at key dynamic sealing locations. These sealing rings are installed between the eccentric shaft 102 and the pin fixing housing, as well as at the connection between the two housing sections, effectively isolating the internal and external environments and achieving cavity sealing.

[0128] The above embodiments, through pre-lubrication and fully enclosed design, can achieve the goal of long-term maintenance-free operation, thereby improving product reliability and service life.

[0129] The preferred features in the above embodiments can be used individually in any embodiment, or in any combination thereof, provided they do not conflict with each other. Furthermore, parts not described in detail in the embodiments can be implemented using existing technologies.

[0130] The following examples and comparative examples will be used to further illustrate this application in order to better understand the above-mentioned technical solutions. It should be understood that the following are only some examples and are not intended to limit this application.

[0131] Application Example 1:

[0132] This application example is a joint module with an embedded cycloidal pinwheel reducer axial flux, including an axial flux motor 200, a reduction transmission module 100, and a sensing device 300 coaxially nested. In this embodiment, the reduction transmission module 100 uses a cycloidal pinwheel reducer, and the sensing device 300 uses an encoder. The axial flux motor 200 includes an upper stator winding 2021, a lower stator winding 2022, and a rotor assembly 201 located between them. The rotor assembly 201 is connected to the rotor force transmission sleeve 400 and maintains an air gap with the upper stator winding 2021 and the lower stator winding 2022. The cycloidal pinwheel reducer includes a pin fixing shell, an eccentric shaft 102, a cycloidal wheel, and an output shaft 103. The pin fixing shell is embedded inside the axial flux motor 200, and its inner wall is provided with a ring of pins 106. The lower end of the eccentric shaft 102 is connected by a double flat structure 10. The rotor transmission sleeve 400 receives torque and has an eccentric section on the upper part, on which a cycloidal wheel is installed. The external teeth of the cycloidal wheel mesh with the pin 106. The number of external teeth of the cycloidal wheel is one less than that of the pin 106. Driven by the eccentric shaft 102, it performs eccentric rolling motion around the pin 106 to achieve deceleration transmission. The output shaft 103 is linked with the cycloidal wheel to output the decelerated rotational motion. The rotor part of the encoder is coaxially connected to the output shaft 103, and the stator part is fixed on the stationary structure. It is used to collect the actual position and speed information of the output end to realize the end closed-loop control.

[0133] The rotor part of the encoder includes a reducer-end encoder shaft 308 located at the top of the cycloidal pinwheel reducer and an inner rotor core 307 located at the bottom. The reducer-end encoder shaft 308 passes through the output shaft 103 and the eccentric shaft 102 from top to bottom and is connected to the inner rotor core 307 of the encoder at the bottom through a double flat structure 10. The upper end of the reducer-end encoder shaft 308 is provided with a threaded hole and a pin, which are fixedly connected to the output shaft 103 to achieve synchronous rotation.

[0134] A rear cover 501 is provided at the bottom of the entire joint module, on which power input / output connectors and communication interfaces are provided; the drive board 502 is fixed above the rear cover 501 and is used to control the operation of the axial flux motor 200; the stator part of the encoder is fixedly connected to the drive board 502 and remains stationary.

[0135] The specific transmission process of the joint module with embedded cycloidal pinwheel reducer axial magnetic flux is as follows:

[0136] After electrical energy is input, the drive board 502 controls the upper and lower stator windings of the axial flux motor 200 to generate a rotating magnetic field, which drives the rotor assembly 201 to rotate and transmits the torque to the eccentric shaft 102 through the rotor force transmission sleeve 400. The eccentric shaft 102 drives the cycloidal wheel to perform eccentric rolling motion on the fixed pin 106, and uses the difference in the number of teeth to achieve a high speed ratio reduction. The decelerated motion is output by the output shaft 103 to complete the power transmission. At the same time, the rotor part of the encoder is coaxially linked with the output shaft 103, while the stator part is fixed, and the position and speed information of the output end are collected in real time to realize the closed-loop control at the end.

[0137] This embodiment arranges the axial flux motor, cycloidal pinwheel reducer, and encoder coaxially along the same axis of rotation, embedding the reduction transmission module within the annular space in the middle of the motor. This eliminates the need for traditional external couplings and transition supports, reducing the number of axial assembly layers. Compared to a split structure, the overall axial dimension is reduced by approximately one-third under the same output torque conditions.

[0138] The power transmission path is as follows: rotor assembly, rotor force transmission sleeve, eccentric shaft, cycloidal wheel, and output shaft. The rotor force transmission sleeve and eccentric shaft are connected using a double-flat structure, eliminating the need for keys, splines, or pins, thus avoiding starting lag and periodic phase fluctuations caused by clearances. Furthermore, this connection method does not rely on elastic elements, reducing torsional deformation and improving dynamic response consistency.

[0139] The encoder rotor is rigidly connected to the output shaft via the encoder shaft at the reducer end, reflecting the actual position of the output end in real time. The stator is fixed to a static reference formed by the rear cover and the bearing retaining ring, forming an independent position detection link. This structure avoids the influence of backlash, clearance, and lubrication aging on the feedback signal, reducing measurement errors.

[0140] In the description of the embodiments of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the 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.

[0141] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0142] In the description of the embodiments in this application, "multiple" means two or more, unless otherwise explicitly specified. In this application, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0143] The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or devices.

[0144] The foregoing has described some specific embodiments of this application. It should be understood that this application is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this application. The above-described preferred features can be used in any combination without conflict.

Claims

1. A joint module, characterized in that, The system includes an axial flux motor, a reduction gear transmission module, and a sensing device integrated along the same axis of rotation. The reduction gear transmission module is embedded radially inside the axial flux motor, and the sensing device is located at the top or bottom of the axial flux motor. The axial flux motor includes a stator assembly and a rotatable rotor assembly. The input end of the reduction gear transmission module is connected to the rotor assembly. The sensing device is connected to the output shaft of the reduction gear transmission module to collect the actual rotational position and speed information of the output end in real time, thereby achieving full closed-loop control of the output end. The axial flux motor adopts a dual-stator, single-rotor structure, including an upper stator winding and a lower stator winding coaxially arranged, and a rotor assembly located between them. Axial air gaps are formed between the rotor assembly and the upper stator winding, and between the rotor assembly and the lower stator winding, respectively, to form a dual-air gap magnetic field path. The system also includes a rotor force transmission sleeve. The rotor force transmission sleeve is fixed in the inner hole of the rotor assembly and rotates synchronously with the rotor assembly. The input end of the reduction gear transmission module transmits torque to the rotor assembly through the rotor force transmission sleeve, thereby establishing a transmission... The rotor transmission sleeve has multiple coaxially nested stepped holes and stepped shafts inside. The stepped holes are used to cooperate with the input end of the reduction gear transmission module to transmit torque, allow the encoder shaft to pass through, and fix the rotor component of the encoder. The stepped shaft is used to install the rotor support bearing. The outer ring of the rotor support bearing is fixed to the inner hole of the lower stator winding and is limited by the bearing retaining ring to ensure the fixed position. The rotor transmission sleeve has a bowl-shaped structure, and its maximum diameter is tightly fitted to the inner hole of the rotor assembly. The rotor transmission sleeve and the input end of the reduction gear transmission module are connected in a dynamic manner. The input end is connected via a double-flat structure, and the sensor and the output end of the reduction transmission module are connected via the same double-flat structure. The rotor force transmission sleeve is equipped with an inclined air duct to achieve active cooling by self-fanning. The stator assembly is equipped with a VC heat dissipation plate to dissipate heat from the motor, and the air duct forms an angle of 10° to 15° with the axis. It also includes a shell that encloses the entire joint module, and has multiple stepped rings on its exterior to increase the heat dissipation surface area. The above structure constitutes a three-level collaborative mechanism of internal active airflow, intermediate uniform temperature diffusion, and external expanded heat dissipation.

2. The joint module according to claim 1, characterized in that, The reduction transmission module is a cycloidal pinwheel reducer, including an eccentric shaft, a fixed housing, a cycloidal wheel, and an output shaft. One end of the eccentric shaft is connected to the output end of the axial flux motor to receive torque, and the other end is an eccentric section for mounting the cycloidal wheel. The inner wall of the fixed housing is provided with multiple first components evenly distributed circumferentially, and the cycloidal wheel is provided with corresponding second components. The first components and the second components slide or roll in cooperation. When the eccentric shaft drives the cycloidal wheel to make eccentric movements, the second components roll or slide relative to the first components, causing the cycloidal wheel to rotate in the opposite direction while revolving around the eccentric shaft, thereby realizing the reduction transmission. The output shaft is connected to the cycloidal wheel and outputs the reduced rotational motion.

3. The joint module according to claim 2, characterized in that, The number of the second component is 1 less than the number of the first component, and the reduction ratio γ satisfies the formula: γ=N2 / (N1-N2), where N1 is the number of the first component and N2 is the number of the second component.

4. The joint module according to claim 1, characterized in that, The sensing device includes a sensing rotor and a measuring stator. The sensing rotor is connected to the reduction transmission module. The measuring stator is fixed and collects the position and speed information of the sensing rotor.

5. The joint module according to claim 1, characterized in that, The internal cavity of the speed reduction transmission module is filled with grease and is equipped with a sealing ring to prevent grease leakage and the intrusion of external contaminants.

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