Inner rotor air-cooled joint module

Abstract

The utility model discloses an inner rotor air -cooled joint module relates to robot joint technical field, including speed reducer subassembly, rotor yoke, front end cover and middle shell, the coaxial fixed joint of speed reducer subassembly's center wheel with rotor yoke, the periphery of rotor yoke is fixed with rotor magnetic steel, the inner wall of middle shell is closely connected with stator core, rotor magnetic steel and stator core cooperation drive, rotor yoke is equipped with end face part, the end face part is equipped with the protruding impeller piece, the impeller piece is equipped with the expansion of several inclined plane sections of air supply angle, rotor yoke with middle shell all have the heat conduction performance, the front end cover has opened several vent holes. The utility model discloses the technical problem to be solved lies in providing an inner rotor air -cooled joint module, in the compact structure layout, rotor and stator are close to the shell piece, provide the best heat conduction path, rotor yoke tail part sets up the impeller structure of axial addition radial blowing, provides the high -speed airflow, improves the air -cooled heat dissipation effect.

Description

Technical Field

[0001] This utility model relates to the field of robot joint technology, specifically to an internal rotor air-cooled joint module. Background Technology

[0002] Currently, the mainstream drive solutions for robot joint modules mainly include two technical routes: frameless motors and disc motors combined with gearboxes. Although these solutions each have their advantages in torque output, response speed, and size control, under high load and high frequency operating conditions, a large amount of heat is generated by the stator and rotor losses of the motor, the friction losses of the reducer, and the switching losses of the power electronic devices (controller). If the heat cannot be dissipated in a timely and effective manner, it will lead to demagnetization of the motor magnets, aging of the winding insulation, lubrication failure of the reducer, and degradation or even damage to the performance of electronic components, seriously restricting the continuous output capability, service life, and operational safety of the joint module. To address the heat dissipation requirements of joint modules, the industry commonly employs the following solutions: Natural / Passive Cooling: Relying on the surface of the casing for heat dissipation, this method is simple in structure but has extremely low heat dissipation efficiency, making it difficult to meet the needs of medium- to high power density joints; Forced Air Cooling: This method involves adding independent fans externally or internally to the module for heat dissipation. While this solution can improve heat dissipation capacity to some extent, the additional fans and their drive circuits occupy valuable internal space within the joint, increasing weight and complexity. Furthermore, heat dissipation efficiency is limited by fan size and airflow design, offering limited improvement for highly integrated, compact joint modules; Liquid Cooling: This method uses coolant circulation to remove heat, resulting in higher heat dissipation efficiency. However, liquid cooling systems require additional components such as liquid cooling plates, piping, pumps, and radiators, significantly increasing the overall weight, volume, and system complexity of the joint module. This contradicts the goal of collaborative robots pursuing extreme lightweighting and compactness, while also increasing cost and maintenance difficulty. Therefore, existing heat dissipation solutions, when applied to collaborative robot joint modules that pursue high power density, lightweight, and compact structure, generally present a contradiction between heat dissipation efficiency and space / weight constraints: efficient heat dissipation (such as liquid cooling) often comes at the cost of sacrificing the lightweight and compactness of the joint; while simple solutions (such as basic air cooling or natural heat dissipation) are difficult to meet the heat dissipation requirements of continuous high power output. Developing a new heat dissipation technology that can significantly improve heat dissipation efficiency without adding extra weight and space burden to the joint module has become a core technical challenge that urgently needs to be solved for current high power density robot joint modules. Furthermore, existing forced air cooling has wind force in the axial direction but lacks airflow heat dissipation in the radial direction, resulting in an incomplete and inadequate heat dissipation effect. Utility Model Content

[0003] Technical problem to be solved by the utility model

[0004] The technical problem to be solved by this utility model is to provide an internal rotor air-cooled joint module. In a compact structural layout, the rotor and stator are closely attached to the housing to provide the best heat conduction path. The rotor yoke tail is provided with an impeller structure with axial and radial air blowing to provide high-speed airflow and improve the air-cooling heat dissipation effect.

[0005] Technical solution

[0006] To solve the above problems, the technical solution provided by this utility model is as follows:

[0007] An internal rotor air-cooled joint module includes a reducer assembly, a rotor yoke, a front end cover, and a middle shell. The central wheel of the reducer assembly and the rotor yoke are coaxially fixed. Rotor magnets are fixed to the periphery of the rotor yoke. A stator core is tightly connected to the inner wall of the middle shell. The rotor magnets and the stator core cooperate to drive each other. The rotor yoke has an end face with protruding impeller blades. The impeller blades have several inclined sections to expand the air delivery angle. Both the rotor yoke and the middle shell have thermal conductivity. The front end cover has several ventilation holes.

[0008] Reducer assembly + rotor yoke (coaxially fixed): Enables power transmission; the embedded design saves space. Rotor magnets + stator core: Form the core of the internal rotor motor, generating driving force and the main heat. Stator core + intermediate shell (tightly connected): Provides the optimal heat conduction path from the stator to the outer shell. Rotor yoke end face + impeller blades + inclined section: Impeller blades (protruding from the end face): Act as active heat dissipation elements, generating high-speed airflow when the rotor rotates. Inclined section: Optimizes airflow direction, widens the air delivery angle, and achieves comprehensive forced air cooling in both the axial and radial directions. Rotor yoke + intermediate shell (thermal conductivity): Acts as a heat transfer medium, assisting in the transfer of heat from the inside to the external heat-dissipating area. Overall structural layout: The planetary reducer is embedded in the rotor yoke, the stator is tightly attached to the outer shell, and the impeller is integrated at the end of the rotor yoke, achieving a balance between extreme compactness and efficient heat dissipation at high power density. Ventilation holes are used for airflow cooling and ventilation.

[0009] Optionally, a connecting sleeve is provided at the center of the rotor yoke, and the connecting sleeve is connected to the primary center wheel and the encoder rotor.

[0010] The connecting bushing (located at the center of the rotor yoke) serves as the physical interface and rotational reference. Function 1 (connecting the first-stage center gear): Transmits torque, directly and rigidly inputting the motor rotor's power to the first stage (sun gear) of the planetary reducer, initiating the deceleration process. Function 2 (connecting the encoder rotor): Transmits rotational status, ensuring the encoder rotor rotates strictly synchronously with the motor rotor, providing precise position and speed feedback signals to the control system. First-stage center gear (connected object): The input stage (sun gear) of the planetary reducer, receiving torque from the motor rotor and marking the starting point of the deceleration and torque increase process. Encoder rotor (connected object): The rotating component of the position sensor; its rotation angle accurately reflects the actual position of the motor rotor, serving as a key information source for closed-loop control.

[0011] Optionally, the reducer assembly includes a primary center gear and a secondary center gear. The primary center gear meshes with a primary planetary gear. The primary planetary gear is installed between a primary planetary support and a primary planetary support. The primary planetary support is fixed to the secondary center gear. The secondary center gear meshes with the secondary planetary gear. The secondary planetary gear is installed on the secondary planetary support.

[0012] A high reduction ratio is achieved through the series connection of two-stage planetary gear trains. The power transmission path is clear: first-stage central gear (input) → first-stage planetary gears → first-stage planetary carrier (revolution) → (through fixed connection) second-stage central gear → second-stage planetary gears → second-stage planetary carrier (output). The direct fixed connection between the first-stage planetary carrier and the second-stage central gear eliminates the need for an intermediate shaft, which is a key design point for achieving an extremely compact structure (embedded in the rotor yoke).

[0013] Optionally, the inclined section includes several inclined sections with increasing angles, the angle being the angle formed by the inclined section and the end face.

[0014] Inclined section: The core functional surface of the impeller blade, its shape directly determines the airflow direction and efficiency. Angle: Specifically refers to the angle between the inclined section and the rotor yoke end face, a key design parameter affecting the airflow direction (axial component vs. radial component). Several inclined sections with increasing angles: "Several": indicates that the impeller blade has multiple inclined sections with different angles. "Increasing angles": a core design feature, referring to the fact that the angles of these inclined sections gradually increase along the blade (usually from the inner edge to the outer edge).

[0015] Functions and Effects: Matching Airflow Velocity Distribution: The linear velocity varies at different radii of the blades during rotation (outer edge > inner edge). Gradually increasing the angle allows for better utilization of this velocity difference. Optimizing Airflow Direction: Small angle segments (near the inner edge) emphasize axial airflow (direct blowing); large angle segments (near the outer edge) emphasize radial (centrifugal) airflow (diffusion). Expanding Airflow Angle and Coverage: By simultaneously generating axial and radial airflow components, a three-dimensional, all-around cooling airflow field is formed, which can more effectively cover heat source areas in complex spaces within the module (such as winding ends and gear meshing areas), eliminating heat dissipation dead zones. Improving Heat Dissipation Efficiency and Uniformity: A more comprehensive and powerful airflow directly enhances the forced convection heat transfer effect, resulting in a lower overall temperature rise and more uniform temperature distribution within the module.

[0016] Optionally, the inclined sections are provided with rounded transition sections.

[0017] The rounded transition section, connecting adjacent inclined sections, is a smooth, curved surface. Functions and effects: Optimizes airflow dynamics: Reduces flow separation and turbulence: Avoids airflow stripping and vortex generation caused by sharp corners. Reduces flow resistance: Allows for a smoother transition of airflow from one inclined plane to the next. Maintains airflow velocity and energy: Reduces energy loss, improving overall fan efficiency (CFM / W) and air pressure. Enhances structural reliability: Eliminates stress concentration: The rounded shape evenly distributes the enormous centrifugal and aerodynamic forces generated by high-speed rotation, preventing stress concentration at sharp corners. Improves fatigue strength: Significantly reduces the risk of fatigue fracture at the joints of blades under alternating loads. Improves overall structural stiffness and durability: Enables impeller blades to withstand long-term high-speed operation. Improves manufacturability and processability: Facilitates forming and processing: The rounded transition makes casting, forging, or CNC machining easier. Reduces the risk of stress corrosion cracking: Smooth surfaces and uniform stress distribution reduce the likelihood of corrosion cracking under specific environmental conditions.

[0018] Optionally, the impeller blades protrude 1cm to 5cm from the end face.

[0019] 1cm~5cm (Protrusion Height Range): 1cm (Lower Limit): Function: Ensures the impeller blades have a basic effective working height. Purpose: Prevents blades that are too short, resulting in weak airflow, inability to overcome internal flow resistance, or ineffective coverage of the heat dissipation area. Ensures an acceptable baseline of heat dissipation performance even with minimal space requirements. 5cm (Upper Limit): Function: Strictly limits the maximum axial dimension of the impeller blades. Purpose: Prevents physical interference with other components within the joint module (such as the rear housing, bearings, reducer extensions, controller PCB, etc.), ensuring module assembly feasibility and operational reliability. This is a rigid constraint to meet the design goals of compact joints. Range (1cm~5cm): Function: Defines the engineering optimization space. Purpose: Provides designers with flexibility to select the optimal protrusion height within this range based on factors such as the power density, internal space margin, and heat dissipation requirements of a specific joint module, achieving the best balance between heat dissipation efficiency and space occupation / structural compatibility. For example, higher-power joints can choose a height close to 5cm if space allows to enhance heat dissipation; joints with tighter space can choose a height close to 1cm while still ensuring basic heat dissipation.

[0020] Alternatively, the impeller blades may have a centrally symmetrical, divergent structure.

[0021] Central Symmetry: Definition: Strictly uniform distribution around the central axis of rotation (e.g., uniform angular intervals of 3, 6, or 9 pieces). Functions and Roles: Dynamic Balance Guarantee: Ensures uniform mass distribution during rotation, eliminating or minimizing unbalanced centrifugal forces. Vibration and Noise Reduction: Dynamic balance is a key prerequisite for the smooth and low-noise operation of the joint module (especially at high speeds). Uniform Airflow Generation: Generates a uniformly distributed, non-periodic turbulent cooling airflow in the circumferential direction, preventing localized overheating.

[0022] Diverging Structure: Definition: The blade shape gradually expands and unfolds from the center of rotation (inner edge) to the outer periphery (outer edge). Function and Role: Matching airflow velocity gradient: During rotation, the linear velocity at different radii of the blade is different (outer edge > inner edge). The diverging structure can naturally utilize the higher linear velocity at the outer edge to push more air. Optimizing airflow direction combination: Inner edge region: Mainly contributes axial airflow, with good penetration depth, directly blowing on the core area of ​​the heat source. Outer edge region: Mainly contributes radial (centrifugal) airflow, with good diffusion coverage, sweeping the inner wall, corners, and radial space of the module. Generating a three-dimensional cooling flow field: It is the physical basis for the efficient combination of axial cooling (penetration) and radial cooling (diffusion) airflow modes. Maximizing heat dissipation area utilization: Within a limited radial space, by expanding the blades outward, the blade sweeping area and the volume of air pushed are increased, thereby improving airflow and air pressure.

[0023] Optionally, annular reinforcing ribs are provided between the impeller blades.

[0024] By connecting discrete blades into a unified frame, the impeller is transformed from "multiple independent cantilever beams" into a "rigid frame structure with ring support," significantly suppressing bending and torsional deformation. It resists centrifugal deformation by directly constraining the radial (outward) displacement of the blades under centrifugal force, preventing excessive outward displacement that could lead to interference with the casing or plastic deformation. It suppresses vibration and noise by increasing structural stiffness and damping, raising the impeller's natural frequency, avoiding resonance with the operating speed or its harmonics, reducing blade flutter, and thus lowering operating noise and vibration. It distributes loads and reduces stress concentration by providing additional force transmission paths, distributing blade loads (especially bending moments in the blade center) more evenly to the rotor yoke body and a wider connection area through the ring support, significantly reducing stress peaks in critical areas such as the blade root and the blade-end junction. It enhances fatigue life by reducing deformation, suppressing vibration, and reducing stress concentration, greatly improving the impeller's ability to resist alternating loads (start-stop, speed changes) and preventing the initiation and propagation of fatigue cracks.

[0025] Optionally, the rotor yoke further includes a sleeve portion, one end of which is provided with a step, and the other end is fixedly connected to a limiting ring, the step and the limiting ring fastening the rotor magnet.

[0026] Sleeve Section: Definition: A cylindrical section on the rotor yoke used to house, support, and fix the rotor magnets. Function: Provides radial support and positioning reference for the magnets; its inner diameter is usually precisely fitted to the outer diameter of the magnets (possibly with adhesive). One end of the sleeve section has a step: Step: A shoulder or stop structure formed on the inner wall or end face of the sleeve section. Location: Located at one end of the sleeve section (axial positioning reference end). Function: Serves as a fixed reference surface for axial positioning of the magnets. During assembly, one end face of the magnet abuts against the step, restricting axial movement of the magnet towards that end. The other end of the sleeve section is fixed with a locating ring: Locating Ring: A separately manufactured annular part (such as a retaining ring, snap ring, or pressure ring). Fixed Connection: Securely connected to the other end of the sleeve section by means of interference fit, welding, threaded fastening, pins, etc. Location: Located at the other end of the sleeve section opposite the step. Function: Presses against the other end face of the magnet, restricting axial movement of the magnet towards that end. Works together with the step to form axial clamping. The steps and limiting rings secure the rotor magnets: Securement: the core action and objective. Function: The steps and limiting rings work together to apply axial restraint force from both ends of the magnets, rigidly and without gaps clamping and fixing the magnets within the sleeve. This design: Eliminates axial movement: Prevents axial displacement of the magnets during start-up, speed changes, or vibration. Resists centrifugal force: Ensures the magnets remain stable at high speeds. Ensures uniform air gap: Maintains the uniformity of the designed air gap between the magnets and the stator core, which is crucial for motor performance and efficiency. Improves reliability: Prevents motor failures caused by magnet loosening, displacement, breakage, or detachment.

[0027] Beneficial effects

[0028] Compared with the prior art, the technical solution provided by this utility model has the following advantages:

[0029] The core of the technical solution provided by this utility model lies in integrating thermal management into a compact structure. The reducer assembly (usually a planetary reducer) and the rotor yoke are coaxially fixed together via a central wheel, ensuring efficient power transmission. The rotor magnets are fixed to the periphery of the rotor yoke and interact with the stator core, which is tightly connected to the inner wall of the intermediate shell, forming the drive core (internal rotor motor), and the heat generated by it is one of the main heat sources. Crucially, the tight connection between the stator core and the intermediate shell establishes an optimal heat conduction path for the heat generated by the stator, allowing it to be efficiently conducted to the outer shell for dissipation. To actively enhance heat dissipation, protruding impeller blades are designed on the end face of the rotor yoke. Their unique feature is the inclined section structure, which generates high-speed airflow when the rotor rotates at high speed and expands the airflow angle, ensuring that the airflow can effectively cover the axial and radial spaces (compensating for the insufficient radial airflow of traditional air-cooled systems), providing forced convection cooling to the internal components (including the motor itself, the reducer, and adjacent areas). Simultaneously, both the rotor yoke and the intermediate shell themselves have thermal conductivity, further promoting the transfer of internal heat to the external environment or a larger heat dissipation surface. This integrated design cleverly embeds the reducer within the internal space of the rotor yoke. Combined with the heat conduction path of the stator close to the outer shell and the active air cooling of the impeller integrated at the tail of the rotor yoke, it achieves efficient and all-round heat dissipation within an extremely compact structural layout, solving the problem of temperature rise in high power density joints. Attached Figure Description

[0030] Figure 1 A cross-sectional view of an internal rotor air-cooled joint module proposed for an embodiment of this utility model;

[0031] Figure 2 An axial view of the rotor yoke of an internal rotor air-cooled joint module proposed for an embodiment of this utility model;

[0032] Figure 3 A perspective view of the front end cover of an internal rotor air-cooled joint module according to an embodiment of this utility model;

[0033] Figure 4 A cross-sectional view of the rotor yoke of an internal rotor air-cooled joint module proposed for an embodiment of this utility model;

[0034] 1. Secondary central wheel; 2. Secondary planetary support; 3. Secondary planetary gears; 4. Rear end cover; 5. First-stage planetary support one; 6. First-stage planetary gears; 7. First-stage central wheel; 8. First-stage planetary support two; 9. Rotor yoke; 901. Connecting bushing; 902. Impeller blade; 903. First inclined section; 904. Second inclined section; 905. Limiting ring; 906. Bolt; 907. Sleeve section; 908. Transition section; 909. Reinforcing rib; 9010. End face section; 10. Middle shell; 11. Front end cover; 1101. Ventilation hole; 12. Rotor magnet; 13. Stator core. Detailed Implementation

[0035] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments.

[0036] Example

[0037] Combined with appendix Figure 1-4 An internal rotor air-cooled joint module includes a reducer assembly, a rotor yoke 9, a front end cover 11, and a middle shell 10. The central wheel of the reducer assembly and the rotor yoke 9 are coaxially fixed. Rotor magnets 12 are fixed on the periphery of the rotor yoke 9. A stator core 13 is tightly connected to the inner wall of the middle shell 10. The rotor magnets 12 and the stator core 13 cooperate to drive each other. The rotor yoke 9 has an end face 9010 with protruding impeller blades 902. The impeller blades 902 have several inclined sections to expand the air delivery angle. Both the rotor yoke 9 and the middle shell 10 have thermal conductivity. The front end cover 11 has several ventilation holes 1101.

[0038] A connecting sleeve 901 is located at the center of the rotor yoke 9, connecting the primary center wheel 7 and the encoder rotor. The connecting sleeve 901 is a crucial central structure, serving a dual connection function: firstly, it connects to the primary center wheel 7 (i.e., the sun gear input stage of the planetary reducer), directly and efficiently transmitting the torque generated by the motor rotor to the reducer, driving it to begin the deceleration and torque increase process; secondly, it also connects to the encoder rotor, enabling the encoder rotor to accurately and synchronously follow the rotational motion of the rotor yoke 9 (i.e., the motor rotor). This design ensures that the encoder can detect and feedback the position and speed information of the motor rotor in real time and accurately, providing a vital data foundation for precise closed-loop motion control.

[0039] The reducer assembly includes a primary central gear 7 and a secondary central gear 1. The primary central gear 7 meshes with a primary planetary gear 6, which is mounted between a primary planetary carrier 1 (5) and a primary planetary carrier 2 (8). The primary planetary carrier 2 (8) is fixed to the secondary central gear 1. The secondary central gear 1 meshes with a secondary planetary gear 3, which is mounted on the secondary planetary carrier 2. The reducer assembly employs a two-stage planetary gear reduction design to achieve a high reduction ratio and compact layout. The primary central gear 7 (i.e., the first-stage sun gear) serves as the starting point for power input, directly receiving torque transmitted from the motor rotor yoke 9. This primary central gear 7 meshes with multiple primary planetary gears 6, distributing the input torque to these planetary gears. These primary planetary gears 6 are mounted between the primary planetary carrier 1 (5) and the primary planetary carrier 2 (8). The two carriers work together to support and constrain the primary planetary gears 6 to revolve around the primary central gear 7 and rotate on their own axes. Crucially, the primary planetary carrier 2 (8) not only supports the planetary gears but is also fixed to the secondary central gear 1 (i.e., the second-stage sun gear). This means that the revolution of the first-stage planetary gear 6 (whose speed and torque are the result of the first-stage reduction) directly drives the rotation of the second-stage central gear 1 through the first-stage planetary carrier 8, thus seamlessly inputting the power after the first-stage reduction into the second-stage reduction. Subsequently, the rotating second-stage central gear 1 re-engages with the second-stage planetary gear 3, splitting and reducing the torque in the second stage. Finally, the second-stage planetary gear 3 is mounted on the second-stage planetary carrier 2, which serves as the final output end, converging the revolution of the second-stage planetary gear 3 and outputting low-speed, high-torque rotational power after two stages of reduction and torque amplification to drive the joint movement.

[0040] The inclined section comprises several inclined sections with progressively increasing angles, the angles being the angles formed by the inclined section and the end face. The inclined section is not a single angle, but rather designed as several inclined sections with progressively increasing angles. The "angle" specifically referred to here is defined as the angle between the inclined section and the end face of the rotor yoke 9 to which the impeller blade 902 is attached. This gradually increasing angle design has a clear aerodynamic purpose: when the rotor yoke 9 drives the impeller to rotate at high speed, the gradually increasing angles of the inclined sections at different positions can more effectively match and guide the airflow at different radii. The inclined sections closer to the center of rotation have smaller angles, mainly generating strong axial airflow to directly expel heat backward; while the gradually increasing angles of the inclined sections farther from the center of rotation significantly enhance the radial (centrifugal) airflow component. This airflow pattern, which combines axial and radial components, greatly expands the air supply coverage, allowing the cooling airflow to reach corners and axial gaps inside the module (such as the stator winding ends and reducer components) that were originally difficult to access more comprehensively and efficiently. This significantly improves the overall forced air cooling efficiency and uniformity, making up for the shortcomings of insufficient radial airflow in traditional single-angle blades.

[0041] In this embodiment, the inclined section has two segments, namely a first inclined section 903 and a second inclined section 904. The angle of the first inclined section 903 is 10°, and the angle of the second inclined section 904 is 30°.

[0042] A rounded transition section 908 is provided between the inclined sections. A rounded transition section 908 is specifically provided between adjacent inclined sections. Here, the inclined sections refer to the functional surfaces with different tilt angles on the impeller blades 902, which are responsible for guiding airflow. The rounded transition section 908 refers to the connection area where two adjacent inclined sections meet, designed as a smooth arc surface, rather than sharp edges or right angles. This design has several key functions: First, the rounded corner transition significantly improves the smoothness of airflow on the blade surface, preventing severe separation of airflow at sharp corners, thus avoiding the formation of turbulence or eddies, reducing flow resistance loss, maintaining the energy and speed of high-speed airflow, and improving fan efficiency; Second, the rounded corner design effectively disperses the centrifugal stress and aerodynamic load borne by the blades during high-speed rotation, eliminating stress concentration points, greatly enhancing the mechanical strength and fatigue resistance of the impeller blade 902, and preventing the blades from cracking or failing at the joints under long-term high-speed operation; Finally, the smooth arc transition also facilitates manufacturing (such as casting or machining) and demolding, and reduces the potential risk of stress corrosion.

[0043] The impeller blade 902 protrudes 1cm to 5cm from the end face. In this embodiment, the impeller blade 902 may protrude 1cm, 3cm, or 5cm from the end face. The height of the protruding end face is precisely set within the range of 1cm to 5cm. Here, the protruding end face specifically refers to the amount of protrusion of the impeller blade 902 relative to the end face (reference surface) of the rotor yoke 9 to which it is attached in the axial direction. This 1cm to 5cm protrusion height range has significant engineering implications: First, it ensures that the impeller blade 902 has sufficient projected area and swept volume, enabling it to push a sufficient amount of air during high-speed rotation, generating a strong forced airflow. This provides effective forced convection cooling for key heat sources inside the module (such as stator windings and reducers), while a height below 1cm may result in insufficient airflow. Second, this height range fully considers the extremely compact space constraints inside the joint module. The upper limit of 5cm strictly limits the space occupied by the impeller blade 902 in the axial direction, preventing interference with adjacent components (such as the back cover, reducer, or electronic components), and ensuring the high integration of the overall module structure. At the same time, the lower limit of 1cm also ensures that the impeller blade 902 has basic airflow guiding and pressurization capabilities, and can play a certain role in heat dissipation even at the minimum height.

[0044] The impeller blade 902 features a centrally symmetrical divergent structure. "Central symmetry" specifically refers to the uniform, mirror-image distribution of all blades around the rotational axis of the rotor yoke 9; that is, from an axial perspective, the blades exhibit strict rotational symmetry in the circumferential direction. This symmetry ensures that the centrifugal force and aerodynamic force generated by the impeller blade 902 are completely balanced in the circumferential direction when the rotor rotates at high speed, thereby minimizing vibration sources and guaranteeing smooth operation and low noise for the joint module. Simultaneously, the term "divergent structure" vividly describes the morphological characteristics of the impeller blade 902: its blades begin at the inner edge (root) near the rotational center and gradually extend radially towards the outer edge (top) away from the center. This divergent shape offers a core aerodynamic advantage: when the impeller rotates at high speed with the rotor, the blade portion near the inner edge primarily generates axial airflow (the airflow direction is roughly parallel to the rotational axis), providing penetrating cooling to the module's interior; while as the blades diverge outwards, the generated airflow component significantly enhances radial (centrifugal) flow. This airflow pattern, which gradually transitions from being dominated by the axial direction to a balance between the axial and radial directions, is the macroscopic realization of the design intent of the gradually changing angle of the inclined section.

[0045] Annular reinforcing ribs 909 are provided between the impeller blades 902. In the centrally symmetrical divergent impeller blade 902 design, to cope with the huge centrifugal force and aerodynamic load generated by high-speed rotation, and to ensure the overall rigidity and stability of the impeller structure, annular reinforcing ribs 909 are specially provided between adjacent impeller blades 902. Here, "annular" specifically refers to the reinforcing ribs 909 forming a closed annular structure around the rotational center axis of the rotor yoke 9, and its shape is usually circular or annular, matching the outer contour of the impeller. This annular reinforcing rib 909 has a core mechanical support function: it connects the originally independent impeller blades 902 to each other at their critical height positions (usually in the middle of the blade or in the stress concentration area) and binds them to the central rotor yoke 9, significantly enhancing the structural rigidity of the entire impeller assembly (blades + ribs). This design can effectively resist the bending deformation (centrifugal force causing blades to fly outward) and torsional deformation (aerodynamic unevenness or start / stop transient loads) of the blades under high-speed rotation, prevent excessive blade vibration or resonance, thereby reducing noise and avoiding fatigue fracture. Meanwhile, the annular structure itself has excellent compressive and tensile strength, which can evenly transfer and distribute part of the load borne by the blade to the main structure of the rotor yoke 9, significantly reducing stress concentration at the root of a single blade and in the connection area, and greatly improving the structural reliability and service life of the impeller under long-term high-speed conditions.

[0046] The rotor yoke 9 also includes a sleeve portion 907. One end of the sleeve portion 907 has a step, and the other end is fixed with a limiting ring 905. The step and the limiting ring 905 secure the rotor magnet 12. The sleeve portion 907 constitutes the main cylindrical section of the rotor yoke 9 that accommodates and supports the magnet. To firmly constrain the rotor magnet 12 in the axial direction and prevent it from shifting or loosening under high-speed rotation and vibration, a step is provided at one end of the sleeve portion 907 (usually near the drive end or reducer end). This step is a shoulder structure formed on the inner wall or end face of the sleeve portion 907, serving as a reference surface for axial positioning of the magnet. At the other end of the sleeve portion 907 (usually near the impeller end or non-drive end), a limiting ring 905 is fixed. This limiting ring 905 is an independent annular part (which may be fixed to the sleeve portion 907 by interference fit, welding, thread, or pin, etc.). In this way, the step and the limiting ring 905 together form a precise axial limiting space within the sleeve portion 907. During assembly, the rotor magnet 12 (usually multiple fan-shaped magnets bonded together or assembled into a ring) is pressed or pushed into the sleeve part 907, with one end face abutting against the step and the other end face being pressed by the limiting ring 905, thereby achieving bidirectional rigid fastening of the rotor magnet 12 in the axial direction.

[0047] The limiting ring 905 is fixed to the end face 9010 by eight bolts 906, and the rotor yoke 9 is an integral molded structure.

[0048] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. An internal rotor air-cooled joint module, characterized in that, The device includes a reducer assembly, a rotor yoke, a front end cover, and a middle shell. The center wheel of the reducer assembly and the rotor yoke are coaxially fixed. Rotor magnets are fixed to the periphery of the rotor yoke. A stator core is tightly connected to the inner wall of the middle shell. The rotor magnets and the stator core cooperate to drive each other. The rotor yoke has an end face with protruding impeller blades. The impeller blades have several inclined sections to expand the air delivery angle. Both the rotor yoke and the middle shell have thermal conductivity. The front end cover has several ventilation holes.

2. The internal rotor air-cooled joint module according to claim 1, characterized in that, The rotor yoke has a connecting sleeve at its center, which connects to the primary center wheel and the encoder rotor.

3. The internal rotor air-cooled joint module according to claim 1, characterized in that, The reducer assembly includes a primary center gear and a secondary center gear. The primary center gear meshes with a primary planetary gear. The primary planetary gear is installed between a primary planetary support and a primary planetary support. The primary planetary support is fixed to the secondary center gear. The secondary center gear meshes with the secondary planetary gear. The secondary planetary gear is installed on the secondary planetary support.

4. The internal rotor air-cooled joint module according to claim 1, characterized in that, The inclined section includes several inclined sections with increasing angles, the angle being the angle formed by the inclined section and the end face.

5. The internal rotor air-cooled joint module according to claim 4, characterized in that, The inclined sections are provided with rounded transition sections.

6. The internal rotor air-cooled joint module according to claim 1, characterized in that, The impeller blades protrude 1cm to 5cm from the end face.

7. An internal rotor air-cooled joint module according to claim 1 or 6, characterized in that, The impeller blades have a centrally symmetrical, divergent structure.

8. An internal rotor air-cooled joint module according to claim 7, characterized in that, The impeller blades are provided with annular reinforcing ribs.

9. An internal rotor air-cooled joint module according to claim 1, characterized in that, The rotor yoke also includes a sleeve portion, one end of which is provided with a step, and the other end is fixedly connected to a limiting ring, the step and the limiting ring fastening the rotor magnet.

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