wheel hub motor

Abstract

This application relates to a hub motor, comprising: a stator assembly including windings and a motor shaft fixed thereto, the motor shaft having a locating surface; a rotor assembly including a rotor housing, and an outer rotor module and an inner rotor module fixed thereto, the outer rotor module surrounding the outer side of the inner rotor module, the motor shaft extending between the outer rotor module and the inner rotor module; a support assembly including a bearing and a bushing, the motor shaft passing through the rotor housing, the bearing connecting the motor shaft and the rotor housing, and the bushing fitted onto the motor shaft; the support assembly is detachable and installable to allow the hub motor to switch between a normal state and a field-weakening state; in the normal state, the bushing is installed on the bearing at the end opposite to the locating surface, and the bearing abuts against the locating surface; in the field-weakening state, the bushing is installed on the bearing at the end near the locating surface, with both ends of the bushing abutting against the locating surface and the bearing respectively, and the bearing at the end opposite to the bushing abutting against the rotor housing. This hub motor can apply mechanical field-weakening technology in a dual-rotor motor while ensuring rotor housing rigidity and reducing the risk of scratches.

Description

Technical Field

[0001] This application relates to the field of hub motor technology, and in particular to hub motors. Background Technology

[0002] As the core of distributed drive and skateboard chassis technology in new energy vehicles, the lightweight and high performance of in-wheel motors are crucial. Dual-rotor in-wheel motors, with their unique dual-air-gap structure, can significantly improve torque density and reduce electromagnetic effective mass within the same volume through the coupling effect of the inner and outer rotors, becoming an important direction for lightweight in-wheel motors. However, this solution faces a key challenge at high speeds: due to the increased magnetic load, the motor generates extremely high back electromotive force at high speeds, which can easily exceed the bus voltage, increasing the risk of winding breakdown, thus limiting the maximum operating speed of this type of motor.

[0003] Currently, mechanical field weakening technology (i.e., reducing the effective stack height by axially moving the stator or rotor to lower the back EMF and expand the speed range) is an effective way to solve this problem. However, there are inherent challenges in applying this technology to dual-rotor motors: the air gaps on both sides are prone to generating significant unbalanced magnetic pull during axial movement. The rotor housing of a dual-rotor motor often lacks sufficient rigidity to resist this dynamic radial force, leading to stator-rotor eccentricity and misalignment, and increasing the risk of scraping. Summary of the Invention

[0004] Therefore, it is necessary to provide a hub motor that can apply mechanical field weakening technology in a dual-rotor motor while ensuring the rigidity of the rotor housing and reducing the risk of scratches.

[0005] A hub motor, the hub motor comprising:

[0006] A stator assembly includes a winding and a motor shaft fixedly connected thereto, and also includes a stator core, the winding being wound around the stator core, and the motor shaft having a positioning surface;

[0007] A rotor assembly includes a rotor housing, and an outer rotor module and an inner rotor module fixedly connected thereto. The outer rotor module surrounds the outer side of the inner rotor module, and the windings and the stator core extend along a first direction between the outer rotor module and the inner rotor module.

[0008] A support assembly, including a bearing and a bushing, wherein the motor shaft passes through the rotor housing, the bearing connects the motor shaft and the rotor housing, and the bushing is fitted onto the motor shaft; the support assembly is configured to be detachably mounted to allow the hub motor to switch between a normal state and a weak magnetic state;

[0009] In the normal state, the bushing is installed on the end of the bearing away from the positioning surface along the first direction, and the bearing abuts against the positioning surface. The first direction is the axial direction of the motor shaft. In the weak magnetic state, the bushing is installed on the end of the bearing close to the positioning surface along the first direction. The two ends of the bushing abut against the positioning surface and the bearing, respectively. The end of the bearing away from the bushing abuts against the rotor housing.

[0010] In some embodiments, the motor shaft has an optical shaft portion and a shoulder portion protruding from the outer peripheral surface of the optical shaft portion. The shoulder portion has the positioning surface. The bearing and the bushing are both sleeved on the optical shaft portion. The outer peripheral surface of the optical shaft portion is provided with a first groove and a second groove. In the normal state, the bushing is inserted into the first groove. In the weak magnetic state, the bushing is inserted into the second groove.

[0011] In some embodiments, the support assembly includes a fixing member. In the normal state, the fixing member is located at the end of the bushing away from the bearing and fixes the bushing to the motor shaft. In the weakened magnetic state, the fixing member is located at the end of the bearing away from the bushing and fixes the bearing to the motor shaft.

[0012] In some embodiments, the motor shaft has an optical shaft portion and a shoulder portion protruding from the outer peripheral surface of the optical shaft portion. The shoulder portion has the positioning surface. The bearing and the bushing are both sleeved on the optical shaft portion. The outer diameter of the bushing is D1, and the diameter of the shoulder portion is D2. D1 is greater than D2.

[0013] In some embodiments, the rotor housing includes an end plate and an annular side plate connected to the edge of the end plate, the motor shaft passes through the end plate, the outer rotor module and the inner rotor module are mounted on the side plate, and a reinforcing rib is connected between the inner wall of the side plate and the end plate.

[0014] In some embodiments, the radial thickness of the side plate at the end opposite to the end plate along the first direction is greater than the radial thickness of the side plate at the end near the end plate along the first direction.

[0015] In some embodiments, the outer wall of the side plate has a first boss and a second boss that are spaced apart and protrude outward along the first direction, and a mounting surface for mounting a tire is formed between the first boss and the second boss.

[0016] In some embodiments, the outer rotor module includes an outer rotor core and an outer rotor permanent magnet, the inner rotor module includes an inner rotor core and an inner rotor permanent magnet, the rotor housing has an annular cavity, the outer rotor core is fixed to the outer wall of the annular cavity, the outer rotor permanent magnet is attached to the inner side of the outer rotor core, the inner rotor core is fixed to the inner wall of the annular cavity, the inner rotor permanent magnet is attached to the outer side of the inner rotor core, and the winding extends between the outer rotor permanent magnet and the inner rotor permanent magnet.

[0017] In some embodiments, the external rotor permanent magnet includes multiple sets of external permanent magnet units arranged along the first direction, each set of external permanent magnet units includes multiple external permanent magnet portions arranged at intervals along the circumferential direction, and the external permanent magnet portions in adjacent external permanent magnet units are staggered along the circumferential direction.

[0018] In some embodiments, the inner rotor permanent magnet includes multiple sets of inner permanent magnet units arranged along the first direction, each set of inner permanent magnet units includes multiple inner permanent magnet portions arranged at intervals along the circumferential direction, and the inner permanent magnet portions in adjacent inner permanent magnet units are staggered along the circumferential direction.

[0019] The aforementioned hub motor cleverly achieves mechanical field weakening of the dual-rotor structure through the switching of detachable support components, effectively ensuring the rigidity of the rotor housing to suppress the risk of eccentricity and scratches caused by dynamic radial forces. Specifically, in the field weakening state, by moving the bushing between the bearing and the motor shaft positioning surface, with both ends of the bushing abutting the positioning surface and the bearing respectively, while the other end of the bearing abuts the rotor housing, a relative displacement of the rotor assembly relative to the stator assembly along the axial direction is achieved. This reduces the effective stacking height of the stator and rotor cores, thereby actively reducing the back electromotive force generated by the windings during high-speed operation, expanding the constant power speed range of the motor, and avoiding the risk of overvoltage breakdown. Crucially, in the field weakening state, the bushing is fixed between the bearing and the motor shaft positioning surface, forming a rigid series support structure of "positioning surface-shoulder-bearing-rotor housing". This structure directly transmits the rotor's dynamic radial force borne by the bearing to the motor shaft positioning surface, significantly improving the rotor housing's ability to resist unbalanced magnetic pull, effectively suppressing stator-rotor eccentricity and misalignment, and fundamentally avoiding the risk of scraping under high-speed, field-weakening conditions. This design, with its simple, detachable assembly method, simultaneously solves the dual challenges of field weakening and stiffness enhancement in dual-rotor motors. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a hub motor in one embodiment of this application.

[0021] Figure 2 This is a schematic diagram of a hub motor from another perspective in one embodiment of this application.

[0022] Figure 3 This is a cross-sectional view (in a weak magnetic state) of a hub motor in one embodiment of this application.

[0023] Figure 4 This is a cross-sectional view (normal state) of a hub motor in one embodiment of this application.

[0024] Figure 5 This is a schematic diagram of a rotor assembly in one embodiment of this application.

[0025] Figure 6 This is an exploded view of a rotor assembly in one embodiment of this application.

[0026] Figure 7 This is a top / bottom view of a rotor assembly in one embodiment of this application.

[0027] Figure label:

[0028] 100. Stator assembly; 110. Winding; 120. Motor shaft; 121. Shaft section; 122. Shoulder section; 1221. Positioning surface; 123. Recessed part; 124. Connecting part; 130. Stator housing; 140. Stator core;

[0029] 200. Rotor assembly; 210. Rotor housing; 211. End plate; 2111. Mounting hole; 212. Side plate; 2121. Annular cavity; 2122. First boss; 2123. Second boss; 2124. Mounting surface; 213. Reinforcing rib; 214. Weight reduction hole; 220. Outer rotor module; 221. Outer rotor core; 2211. Outer permanent magnet mounting slot; 222. Outer rotor permanent magnet; 2221. Outer permanent magnet unit; 22211. Outer permanent magnet section; 230. Inner rotor module; 231. Inner rotor core; 2311. Inner permanent magnet mounting slot; 232. Inner rotor permanent magnet; 2321. Inner permanent magnet unit; 23211. Inner permanent magnet section;

[0030] 300, Support assembly; 310, Bearing; 320, Bushing; 330, Fixing element; 331, Fixing part; 332, Blocking part. Detailed Implementation

[0031] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0032] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and 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, and therefore should not be construed as a limitation of this application.

[0033] Furthermore, where the terms "first" and "second" appear, these terms are 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 at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0035] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0037] See Figures 1 to 2 One embodiment of this application provides a hub motor including a stator assembly 100, a rotor assembly 200, and a support assembly 300. See also... Figures 3 to 5 The stator assembly 100 includes a winding 110 and a motor shaft 120 fixedly connected thereto, and also includes a stator core 140, with the winding 110 wound around the stator core 140. The motor shaft 120 has a positioning surface 1221. The rotor assembly 200 includes a rotor housing 210, and an outer rotor module 220 and an inner rotor module 230 fixedly connected thereto. The outer rotor module 220 surrounds the outer side of the inner rotor module 230, and the winding 110 and the stator core 140 extend in a first direction between the outer rotor module 220 and the inner rotor module 230. The support assembly 300 includes a bearing 310 and a bushing 320. The motor shaft 120 passes through the rotor housing 210, the bearing 310 connects the motor shaft 120 and the rotor housing 210, and the bushing 320 is fitted onto the motor shaft 120. The support assembly 300 is configured for detachable installation so that the hub motor can be in a normal state ( Figure 4 ) and weak magnetic state ( Figure 3 Switching between the two states. In the normal state, the bushing 320 is installed on the end of the bearing 310 away from the positioning surface 1221 along the first direction, and the bearing 310 abuts against the positioning surface 1221. The first direction is the axial direction of the motor shaft 120. In the weak magnetic state, the bushing 320 is installed on the end of the bearing 310 close to the positioning surface 1221 along the first direction. The two ends of the bushing 320 abut against the positioning surface 1221 and the bearing 310 respectively. The end of the bearing 310 away from the bushing 320 abuts against the rotor housing 210.

[0038] The hub motor in the above embodiment cleverly achieves the mechanical field weakening function of the dual-rotor structure through the state switching of the detachable support component 300, and effectively ensures the rigidity of the rotor housing 210 to suppress the risk of eccentricity and scratches caused by dynamic radial forces. Specifically, in the field weakening state where field weakening is required, by moving the bushing 320 between the bearing 310 and the positioning surface 1221 of the motor shaft 120, the two ends of the bushing 320 abut against the positioning surface 1221 and the bearing 310 respectively, while the other end of the bearing 310 abuts against the rotor housing 210, the rotor assembly 200 is axially displaced relative to the stator assembly 100, reducing the effective stacking height of the stator and rotor cores, thereby actively reducing the back electromotive force generated by the winding 110 during high-speed operation, expanding the constant power speed range of the motor, and avoiding the risk of overvoltage breakdown. Crucially, under weakened magnetic conditions, the bushing 320 is fixed between the bearing 310 and the positioning surface 1221 of the motor shaft 120, forming a rigid series support structure of "positioning surface 1221 - bushing 320 - bearing 310 - rotor housing 210". This structure directly transmits the rotor dynamic radial force borne by the bearing 310 to the positioning surface 1221 of the motor shaft 120, significantly improving the rotor housing 210's ability to resist unbalanced magnetic pull, effectively suppressing stator-rotor eccentricity and misalignment, and fundamentally avoiding the risk of scraping under high-speed weakened magnetic conditions. This design, with its simple detachable assembly method, simultaneously solves the dual challenges of implementing weakened magnetic force and strengthening rigidity in dual-rotor motors.

[0039] Specifically, in Figure 4 Under the normal conditions shown, the effective stacking height of the stator and rotor cores is S1. Figure 3 Under the weakened magnetic state shown, the effective stacking height of the stator and rotor cores is S2. S2 is significantly smaller than S1. Thus, under the weakened magnetic state, by reducing the effective stacking height of the stator and rotor cores, the back electromotive force generated by winding 110 during high-speed operation is reduced, the constant power speed range of the motor is extended, and the risk of overvoltage breakdown is avoided.

[0040] See Figures 3 to 4 In some embodiments, the motor shaft 120 has an optical shaft portion 121 and a shoulder portion 122 protruding from the outer peripheral surface of the optical shaft portion 121. The shoulder portion 122 has a positioning surface 1221. The bearing 310 and the bushing 320 are both sleeved on the optical shaft portion 121. The outer peripheral surface of the optical shaft portion 121 is provided with a first groove and a second groove. Under normal conditions, the bushing 320 is inserted into the first groove. Under weak magnetic conditions, the bushing 320 is inserted into the second groove.

[0041] Specifically, the diameter of the shoulder portion 122 is larger than that of the optical shaft portion 121, thereby forming a positioning surface 1221 at the end of the shoulder portion 122. The inner ring of the bearing 310 is fitted onto and connected to the optical shaft portion 121 (detachably connected), and the outer ring of the bearing 310 is connected to the rotor housing 210 (preferably detachably connected), thereby realizing a rotational connection between the rotor housing 210 and the motor shaft 120. The first groove and the second groove are arranged at intervals along the first direction, and the diameter of both is smaller than that of the optical shaft portion 121. In the normal state, a portion of the bushing 320 radially closer to the inner side is engaged in the first groove; in the weak magnetic state, a portion of the bushing 320 radially closer to the inner side is engaged in the second groove.

[0042] In the above embodiment, the coordinated design of the optical shaft portion 121 and the shoulder portion 122 significantly improves system reliability while achieving the field weakening function. Specifically, the first and second grooves on the outer circumferential surface of the optical shaft portion 121 provide a precise axial positioning reference for the bushing 320: under normal conditions, the bushing 320 is engaged in the first groove, ensuring assembly stability under standard operating conditions; under field weakening conditions, the bushing 320 is engaged in the second groove, making it tightly adhere to the positioning surface 1221 of the shoulder portion 122, forming a key node of the rigid series structure. This groove engagement mechanism not only simplifies the state switching operation process but also eliminates the risk of axial movement of the bushing 320 through physical limiting. More importantly, the shoulder portion 122, as a rigid boss of the motor shaft 120, provides a high-strength support point for dynamic radial forces with its positioning surface 1221, while the precise fit between the groove and the bushing 320 allows for precise control of axial displacement, avoiding uneven air gap caused by assembly errors during the field weakening process. This design achieves triple gains simultaneously with a minimalist mechanical structure: precise execution of field weakening displacement, a substantial improvement in the deformation resistance of the rotor housing 210, and enhanced operational robustness during state switching, ensuring the dynamic stability and service life of the dual-rotor motor under high-speed field weakening conditions.

[0043] See Figures 2 to 4 In some embodiments, the support assembly 300 includes a fastener 330. In the normal state, the fastener 330 is located at the end of the bushing 320 away from the bearing 310 and fixes the bushing 320 to the motor shaft 120. In the weak magnetic state, the fastener 330 is located at the end of the bearing 310 away from the bushing 320 and fixes the bearing 310 to the motor shaft 120.

[0044] Specifically, the motor shaft 120 has a recessed portion 123, and the recessed portion 123 and the shoulder portion 122 are located at both ends of the optical shaft portion 121 along a first direction, respectively. The recessed portion 123 is recessed relative to the optical shaft portion 121, that is, the diameter of the recessed portion 123 is smaller than that of the optical shaft portion 121. The fastener 330 is installed in the recessed portion 123 to fix the bushing 320 and the bearing 310 to the motor shaft 120 in two states, respectively.

[0045] Furthermore, the fixing member 330 includes a fixing part 331 and a blocking part 332, both of which are sleeved on the recessed part 123, and the fixing part 331 and the recessed part 123 are fixedly connected. Under normal conditions, the blocking part 332 simultaneously presses against the end faces of the bushing 320 and the optical axis part 121, and the fixing part 331 prevents the blocking part 332 from loosening. Under weak magnetic conditions, the blocking part 332 simultaneously presses against the end faces of the bearing 310 and the optical axis part 121, and the fixing part 331 prevents the blocking part 332 from loosening. Optionally, the blocking part 332 is a retaining ring, and the fixing part 331 is a nut, with the nut and the recessed part 123 threaded together.

[0046] In the above embodiment, when the motor is in its normal state, the fixing member 330 is located outside the bushing 320, directly pressing it against the motor shaft 120, forming an axial constraint chain of "positioning surface 1221 → bearing 310 → bushing 320 → fixing member 330", ensuring the positioning stability of the rotor assembly 200 in its normal state. When switching to the weak magnetic state, the locking object of the fixing member 330 changes to the bearing 310. Because the bushing 320 occupies the inner space, the fixing member 330 naturally changes to directly pressing the end face of the bearing 310, forming a rigid series structure of "positioning surface 1221 → bushing 320 → bearing 310 → fixing member 330". This embodiment provides a highly reliable axial locking solution for dual-state switching through the detachable and reconfigurable design of the fixing member 330.

[0047] When it is necessary to switch from the normal state ( Figure 4 Switch to weak magnetic state ( Figure 3 When removing the bearing 310, simply perform the following steps: disassemble the fastener 330 → remove the bushing 320 → remove the bearing 310 → install the bushing 320 on the positioning surface 1221 → install the bearing 310 → install the fastener 330. It should be noted that when removing the bearing 310, the rotor assembly 200 connected to its outer ring must also be removed. Furthermore, during removal, the connection between the inner ring of the bearing 310 and the motor shaft 120 must be disconnected (the two are detachable, for example, by a snap-fit ​​connection).

[0048] See Figures 3 to 4 In some embodiments, the motor shaft 120 has a shaft portion 121 and a shoulder portion 122 protruding from the outer peripheral surface of the shaft portion 121. The shoulder portion 122 has a positioning surface 1221. The bearing 310 and the bushing 320 are both sleeved on the shaft portion 121. The outer diameter of the bushing 320 is D1, and the diameter of the shoulder portion 122 is D2. D1 is greater than D2.

[0049] Understandably, if D1 is less than D2, when disassembling the bushing 320 under weak magnetic conditions, force can only be applied to the outer circumferential surface of the bushing 320, making the operation inconvenient. In the above embodiment, D1 is limited to be greater than D2. Therefore, when disassembling the bushing 320 under weak magnetic conditions, the claw of the disassembly tool can be extended to the end face of the bushing 320 away from the bearing 310 (that is, the end face not blocked by the positioning surface 1221), and a pulling force can be applied to the end face of the bushing 320 to facilitate its removal.

[0050] In addition, the bushing 320 is fitted outside the optical shaft portion 121, and the inner diameter of the bushing 320 and the diameter of the optical shaft portion 121 meet the clearance fit requirements.

[0051] See Figures 2 to 5 In some embodiments, the rotor housing 210 includes an end plate 211 and a side plate 212 that is connected to the edge of the end plate 211 and is annular. The motor shaft 120 passes through the end plate 211. The outer rotor module 220 and the inner rotor module 230 are mounted on the side plate 212. A reinforcing rib 213 is connected between the inner wall of the side plate 212 and the end plate 211.

[0052] Specifically, the reinforcing rib 213 connecting the inner wall of the side plate 212 and the end plate 211 is triangular. In addition, annular reinforcing ribs 213 are also provided on the inner wall of the side plate 212.

[0053] The above embodiment achieves a significant improvement in the deformation resistance of the rotor shell 210 under the premise of lightweight design through the synergistic reinforcement design of the end plate 211, side plate 212, and reinforcing rib 213. The reinforcing rib 213, as a three-dimensional truss connecting the inner walls of the end plate 211 and side plate 212, transforms the traditional single-layer thin-walled shell into a spatial mesh skeleton structure: when the dual-rotor module rotates at high speed and generates dynamic radial magnetic pull, the reinforcing rib 213, through the triangular force transmission principle, efficiently decomposes the radial load concentrated in the middle of the side plate 212 into axial components, and transmits them along the ribs to the rigid area of ​​the end plate 211. In this way, the overall stiffness of the rotor shell 210 can be significantly improved.

[0054] In some embodiments, the end plate 211 is circular, and the side plate 212 is annular. The end plate 211 has a mounting hole 2111 through which the motor shaft 120 passes in a first direction at its center. The side plate 212 has an annular cavity 2121, which is open on the side opposite to the end plate 211 in the first direction. The winding 110 can extend into the space between the outer rotor module 220 and the inner rotor module 230 through this opening in the first direction.

[0055] See Figure 1 and Figure 3In some embodiments, the stator assembly 100 includes a stator housing 130 and a stator core 140, which are fixedly connected, and the stator housing 130 is fixedly connected to the motor shaft 120. A winding 110 is wound around the stator core 140, and the winding 110 and the stator core 140 extend along a first direction between the outer rotor module 220 and the inner rotor module 230. Specifically, the motor shaft 120 includes a connecting portion 124, located at one end of the shaft shoulder 122 opposite to the optical shaft portion 121, and the connecting portion 124 and the stator housing 130 are fixedly connected by threaded fasteners.

[0056] See Figure 3 and Figure 4 In some embodiments, the radial thickness of the side plate 212 away from the end plate 211 along the first direction is greater than the radial thickness of the side plate 212 near the end plate 211 along the first direction.

[0057] In the above embodiments, a gradually thickened design is adopted for the stiffness deficiency of the free end (the end away from the end plate 211) of the side plate 212: the radial thickness of the end of the side plate 212 away from the end plate 211 is increased to form a reinforced structure. When the dual rotors rotate at high speed, the free end of the side plate 212 is most prone to radial instability due to the lack of constraint from the end plate 211. The thickened design increases the moment of inertia of the section in this area, significantly suppressing the "trumpet mouth" deformation trend.

[0058] Preferably, the outer peripheral surface of the side plate 212 is conical, and the diameter of the outer peripheral surface gradually increases in the direction away from the end plate 211 (the inner peripheral surface is a cylindrical surface with an equal diameter). That is, the radial thickness of the entire side plate 212 gradually increases in the direction away from the end plate 211.

[0059] In the above embodiment, by designing the outer peripheral surface of the side plate 212 as a tapered structure that gradually expands towards the free end (the end opposite to the end plate 211), the weakest link of the rotor shell 210 is precisely reinforced using a geometric strengthening strategy. The tapered outer contour increases the cross-sectional area of ​​the free end and enhances the moment of inertia, forming a natural mechanical bending-resistant beam. When the dynamic radial magnetic pull of high-speed rotation acts on the side plate 212, the gradually expanding tapered surface efficiently converts the radial load borne by the free end into circumferential compressive stress through distributed material thickening, significantly suppressing the "trumpet mouth" deformation trend.

[0060] See Figure 5 In some embodiments, the outer wall of the side plate 212 has a first boss 2122 and a second boss 2123 that are spaced apart and protrude outward along a first direction, and a mounting surface 2124 for mounting a tire is formed between the first boss 2122 and the second boss 2123.

[0061] Specifically, the first boss 2122 and the second boss 2123 are respectively located at both ends of the outer wall of the side plate 212 along the first direction.

[0062] In the above embodiment, through the topology optimization design of the first boss 2122 and the second boss 2123, the tire bearing structure is directly constructed on the outer wall of the side plate 212, realizing the integrated integration of the wheel hub and rotor housing. The tire can be directly installed on the mounting surface 2124, thereby reducing weight and unsprung mass. In addition, the "I" beam structure formed by the double bosses improves the bending stiffness of the free end of the side plate 212.

[0063] See Figure 2 and Figure 5 In some embodiments, the rotor housing 210 is also provided with a plurality of weight-reduction holes 214 for further weight reduction. In addition, the weight-reduction holes 214 can also enhance heat dissipation for the motor.

[0064] Specifically, the end plate 211 is provided with a weight-reducing hole 214 extending along the first direction, and the side plate 212 is provided with a weight-reducing hole 214 extending radially. Preferably, the multiple weight-reducing holes 214 on the side plate 212 make the local area of ​​the side plate 212 present a "well"-shaped reinforcement structure, so as to minimize the weakening of its strength and stiffness while reducing weight.

[0065] See Figures 3 to 4 ,as well as Figures 6 to 7 In some embodiments, the outer rotor module 220 includes an outer rotor core 221 and an outer rotor permanent magnet 222, and the inner rotor module 230 includes an inner rotor core 231 and an inner rotor permanent magnet 232. The rotor housing 210 has an annular cavity 2121. The outer rotor core 221 is fixed to the outer wall of the annular cavity 2121, and the outer rotor permanent magnet 222 is attached to the inner side of the outer rotor core 221. The inner rotor core 231 is fixed to the inner wall of the annular cavity 2121, and the inner rotor permanent magnet 232 is attached to the outer side of the inner rotor core 231. The winding 110 extends between the outer rotor permanent magnet 222 and the inner rotor permanent magnet 232.

[0066] Specifically, the winding 110 and the stator core 140 extend along a first direction between the outer rotor permanent magnet 222 and the inner rotor permanent magnet 232. The outer rotor permanent magnet 222 and the inner rotor permanent magnet 232 are surface-mounted permanent magnets. The outer rotor core 221 is mounted to the outer wall of the annular cavity 2121 via an interference fit and is circumferentially positioned via a keyway. Similarly, the inner rotor core 231 is mounted to the inner wall of the annular cavity 2121 via an interference fit and is circumferentially positioned via a keyway.

[0067] The above embodiment, through the independent arrangement of the outer rotor core 221 and the inner rotor core 231, unlocks the core advantages of surface-mount permanent magnets while ensuring high integration. Compared to the integration scheme that omits the rotor core (the permanent magnet is directly embedded in the rotor housing 210), this design attaches the outer rotor permanent magnet 222 to the inner side of the outer rotor core 221 and the inner rotor permanent magnet 232 to the outer side of the inner rotor core 231, achieving a dual-sided surface-mount magnetic circuit layout. The significance of this structure lies in several aspects: First, the surface-mounted layout allows the permanent magnets to directly face the air gap, significantly improving magnetic flux utilization. In contrast, the built-in design, which omits the iron core, requires magnetic conduction through the rotor housing 210, resulting in a higher magnetic leakage coefficient. Second, the silicon steel sheet-laminated rotor core provides an ideal magnetic conduction path for the permanent magnets, leading to a significant breakthrough in peak torque density for the dual-rotor motor, a substantial improvement over coreless designs. More importantly, the laminated rotor core structure absorbs high-frequency electromagnetic vibrations, suppressing eddy current losses in the permanent magnets during high-speed operation within a certain range. In contrast, permanent magnets integrated into the rotor housing 210 experience extremely high eddy current losses due to direct contact with the conductive housing. Although the addition of inner and outer rotor cores increases the weight of the rotor assembly 200, the compact topology design of the annular cavity 2121 still results in an overall weight lighter than traditional split-type dual-rotor motors. This solution achieves a fundamental breakthrough in electromagnetic performance and thermal safety at the cost of controllable weight, laying the dual foundation for high power density and high reliability in hub motors.

[0068] See Figures 3 to 4 ,as well as Figures 6 to 7 In some embodiments, the outer rotor permanent magnet 222 includes multiple sets of outer permanent magnet units 2221 arranged along a first direction. Each set of outer permanent magnet units 2221 includes multiple outer permanent magnet parts 22211 arranged at intervals along the circumferential direction. The outer permanent magnet parts 22211 in adjacent outer permanent magnet units 2221 are staggered along the circumferential direction.

[0069] In the above embodiment, each group of external permanent magnet units 2221 is independently arranged along the axial direction to form a discrete distribution. The external permanent magnet parts 22211 in adjacent units are staggered at a specific angle in the circumferential direction to construct a three-dimensional spiral magnetic pole array. This innovative arrangement brings three core benefits: First, the axial segmentation effectively cuts off the continuous eddy current path of the large-size permanent magnet, confining the eddy current induced during high-speed rotation to a local area and significantly reducing the scale of eddy current loss; second, the circumferential staggered design greatly suppresses torque pulsation and improves vehicle driving smoothness through the phase cancellation effect of spatial harmonics; more importantly, under the dual-rotor magnetic field coupling mechanism, the staggered permanent magnet array and the inner rotor permanent magnet form a complementary magnetic field modulation, optimizing the sine of the air gap magnetic flux density waveform and simultaneously reducing core loss and high-frequency electromagnetic noise.

[0070] Specifically, in the embodiment shown in the accompanying drawings, the outer rotor permanent magnet 222 includes two sets of outer permanent magnet units 2221 arranged along a first direction, wherein the outer permanent magnet portions 22211 of adjacent outer permanent magnet units 2221 are staggered circumferentially by an angle ranging from 0.2 degrees to 20 degrees. Preferably, the staggered angle ranges from 1 degree to 5 degrees. Further, the staggered angle is 0.5 degrees. In other embodiments, the outer rotor permanent magnet 222 includes three, four, or five sets of outer permanent magnet units 2221 arranged along the first direction.

[0071] See Figures 3 to 4 ,as well as Figures 6 to 7 In some embodiments, the inner rotor permanent magnet 232 includes multiple sets of inner permanent magnet units 2321 arranged along a first direction. Each set of inner permanent magnet units 2321 includes multiple inner permanent magnet parts 23211 arranged at intervals along the circumferential direction. The inner permanent magnet parts 23211 in adjacent inner permanent magnet units 2321 are staggered along the circumferential direction.

[0072] In the above embodiment, a three-dimensional harmonic collaborative management mechanism is constructed in the dual-rotor magnetic field coupling through the axial segmentation and circumferential misalignment topology of the inner rotor permanent magnet 232. Multiple sets of inner permanent magnet units 2321 are independently arranged along the axial direction to form discrete magnetic poles. The inner permanent magnet parts 23211 of adjacent units are misaligned at a specific angle in the circumferential direction, so that the magnetic field of the inner rotor and the spiral array of the outer rotor permanent magnet 222 form phase complementarity. This symmetrical design brings triple collaborative gains: First, the axial segmentation effectively blocks the transmission of eddy currents across units in the inner rotor, significantly suppressing the risk of permanent magnet heating during high-speed rotation; second, the circumferential misalignment layout modulates the phase difference of the inner and outer rotor harmonics, so that the torque pulsation components cancel each other out, greatly improving the low-speed stability of the motor; more importantly, the spatial phase offset between the inner rotor misalignment array and the outer rotor forms a cascaded magnetic field modulation effect, forcing the high-order harmonics of the air gap magnetic flux density to decouple from each other, which not only reduces the high-frequency loss of the iron core, but also eliminates specific order electromagnetic noise.

[0073] Specifically, in the embodiment shown in the accompanying drawings, the inner rotor permanent magnet 232 includes two sets of inner permanent magnet units 2321 arranged along a first direction, wherein the inner permanent magnet portions 23211 of adjacent inner permanent magnet units 2321 are staggered circumferentially by an angle ranging from 0.2 degrees to 20 degrees. Preferably, the staggered angle ranges from 1 degree to 5 degrees. Further, the staggered angle is 0.5 degrees. In other embodiments, the inner rotor permanent magnet 232 includes three, four, or five sets of inner permanent magnet units 2321 arranged along the first direction.

[0074] In some embodiments, the direction in which the outer permanent magnet portions 22211 of two adjacent sets of outer permanent magnet units 2221 are staggered circumferentially is the same as the direction in which the inner permanent magnet portions 23211 of two adjacent sets of inner permanent magnet units 2321 are staggered circumferentially. For example, in the embodiment shown in the figures, a set of outer permanent magnet units 2221 that are close to the end plate 211 along the first direction is the first set of outer permanent magnet units, and a set of outer permanent magnet units 2221 that are away from the end plate 211 is the second set of outer permanent magnet units; a set of inner permanent magnet units 2321 that are close to the end plate 211 along the first direction is the first set of inner permanent magnet units, and a set of inner permanent magnet units 2321 that are away from the end plate 211 is the second set of inner permanent magnet units. The second set of outer permanent magnet units is staggered clockwise relative to the first set of outer permanent magnet units, and the second set of inner permanent magnet units is staggered clockwise relative to the first set of inner permanent magnet units.

[0075] Alternatively, in other embodiments, the direction in which the outer permanent magnet portions 22211 of two adjacent sets of outer permanent magnet units 2221 are offset circumferentially is opposite to the direction in which the inner permanent magnet portions 23211 of two adjacent sets of inner permanent magnet units 2321 are offset circumferentially. For example, the second set of outer permanent magnet units is offset clockwise relative to the first set of outer permanent magnet units, and the second set of inner permanent magnet units is offset counterclockwise relative to the first set of inner permanent magnet units.

[0076] In some embodiments, the outer rotor core 221 is provided with a plurality of outer permanent magnet mounting slots 2211 corresponding one-to-one with a plurality of outer permanent magnet portions 22211, and each outer permanent magnet portion 22211 is fixed within one outer permanent magnet mounting slot 2211. Specifically, each outer permanent magnet portion 22211 is bonded to one outer permanent magnet mounting slot 2211. Preferably, the outer permanent magnet mounting slot 2211 is a dovetail groove to prevent the outer permanent magnet portion 22211 from falling out.

[0077] In some embodiments, the inner rotor core 231 is provided with a plurality of inner permanent magnet mounting slots 2311 corresponding one-to-one with a plurality of inner permanent magnet portions 23211, and each inner permanent magnet portion 23211 is fixed in one inner permanent magnet mounting slot 2311. Specifically, each inner permanent magnet portion 23211 is bonded to one inner permanent magnet mounting slot 2311. Preferably, the inner permanent magnet mounting slot 2311 is a dovetail groove to prevent the inner permanent magnet portion 23211 from falling out.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A hub motor, characterized in that, The hub motor includes: A stator assembly includes a winding and a motor shaft fixedly connected thereto, and also includes a stator core, the winding being wound around the stator core, and the motor shaft having a positioning surface; A rotor assembly includes a rotor housing, and an outer rotor module and an inner rotor module fixedly connected thereto. The outer rotor module surrounds the outer side of the inner rotor module, and the windings and the stator core extend along a first direction between the outer rotor module and the inner rotor module. A support assembly, including a bearing and a bushing, wherein the motor shaft passes through the rotor housing, the bearing connects the motor shaft and the rotor housing, and the bushing is fitted onto the motor shaft; the support assembly is configured to be detachably mounted to allow the hub motor to switch between a normal state and a weak magnetic state; In the normal state, the bushing is installed on the end of the bearing away from the positioning surface along the first direction, and the bearing abuts against the positioning surface. The first direction is the axial direction of the motor shaft. In the weak magnetic state, the bushing is installed on the end of the bearing close to the positioning surface along the first direction. The two ends of the bushing abut against the positioning surface and the bearing, respectively. The end of the bearing away from the bushing abuts against the rotor housing.

2. The hub motor according to claim 1, characterized in that, The motor shaft has an optical shaft portion and a shoulder portion protruding from the outer peripheral surface of the optical shaft portion. The shoulder portion has the positioning surface. The bearing and the bushing are both sleeved on the optical shaft portion. The outer peripheral surface of the optical shaft portion is provided with a first groove and a second groove. In the normal state, the bushing is inserted into the first groove. In the weak magnetic state, the bushing is inserted into the second groove.

3. The hub motor according to claim 1, characterized in that, The support assembly includes a fixing member. In the normal state, the fixing member is located at the end of the bushing away from the bearing and fixes the bushing to the motor shaft. In the weakened magnetic state, the fixing member is located at the end of the bearing away from the bushing and fixes the bearing to the motor shaft.

4. The hub motor according to claim 1, characterized in that, The motor shaft has a light shaft portion and a shoulder portion protruding from the outer peripheral surface of the light shaft portion. The shoulder portion has the positioning surface. The bearing and the bushing are both fitted onto the light shaft portion. The outer diameter of the bushing is D1, and the diameter of the shoulder portion is D2. D1 is greater than D2.

5. The hub motor according to claim 1, characterized in that, The rotor housing includes an end plate and a ring-shaped side plate connected to the edge of the end plate. The motor shaft passes through the end plate. The outer rotor module and the inner rotor module are mounted on the side plate. A reinforcing rib is connected between the inner wall of the side plate and the end plate.

6. The hub motor according to claim 5, characterized in that, The radial thickness of the side plate at the end opposite to the end plate along the first direction is greater than the radial thickness of the side plate at the end closer to the end plate along the first direction.

7. The hub motor according to claim 5, characterized in that, The outer wall of the side plate has a first boss and a second boss that are spaced apart and protrude outward along the first direction, and a mounting surface for mounting a tire is formed between the first boss and the second boss.

8. The hub motor according to any one of claims 1 to 7, characterized in that, The outer rotor module includes an outer rotor core and an outer rotor permanent magnet, and the inner rotor module includes an inner rotor core and an inner rotor permanent magnet. The rotor shell has an annular cavity. The outer rotor core is fixed to the outer wall of the annular cavity, the outer rotor permanent magnet is attached to the inner side of the outer rotor core, the inner rotor core is fixed to the inner wall of the annular cavity, and the inner rotor permanent magnet is attached to the outer side of the inner rotor core. The winding extends between the outer rotor permanent magnet and the inner rotor permanent magnet.

9. The hub motor according to claim 8, characterized in that, The external rotor permanent magnet includes multiple sets of external permanent magnet units arranged along the first direction. Each set of external permanent magnet units includes multiple external permanent magnet parts arranged at intervals along the circumferential direction. The external permanent magnet parts in adjacent external permanent magnet units are staggered along the circumferential direction.

10. The hub motor according to claim 8, characterized in that, The inner rotor permanent magnet includes multiple sets of inner permanent magnet units arranged along the first direction. Each set of inner permanent magnet units includes multiple inner permanent magnet parts arranged at intervals along the circumferential direction. The inner permanent magnet parts in adjacent inner permanent magnet units are staggered along the circumferential direction.

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