Hub motors and electric vehicles

Abstract

The present invention discloses a hub motor and an electric vehicle. The hub motor includes a central shaft and a housing assembly, a stator assembly, a rotor assembly, and a gear assembly connected to the central shaft. The housing assembly and the rotor assembly are both supported on the central shaft via bearings. The stator assembly includes a stator core and windings. The stator core has a closed yoke with a plurality of teeth disposed on the outer periphery of the yoke. Windings are wound around the teeth and are made of aluminum wire. The rotor assembly includes a permanent magnet made of ferrite. The rotor assembly and the housing assembly are connected to each other via a gear assembly. The rotor assembly of the hub motor drives the housing assembly to rotate via the gear assembly. The housing assembly is connected to the wheels of the electric vehicle to enable the vehicle to travel. The windings use aluminum wire instead of copper conductors, and the permanent magnets of the rotor assembly use ferrite instead of expensive rare earth permanent magnets, which helps reduce the manufacturing cost of the hub motor.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a hub motor and an electric vehicle. Background Art

[0002] In related technologies, the hub motor is a direct-drive motor. In order to output greater torque and ensure motor efficiency, the windings are all made of copper conductors, and the permanent magnets are all made of rare earth permanent magnets. The raw material costs of copper and rare earth permanent magnets are high, especially rare earth permanent magnets, which are rare metals, and the raw material costs are even more expensive. Therefore, the use of copper windings and rare earth permanent magnets in hub motors will result in excessively high costs and waste rare metal resources. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a hub motor with a stator assembly having a large winding slot fill rate, which effectively improves power density and efficiency.

[0004] The present invention also provides an electric vehicle having the above-mentioned hub motor.

[0005] According to an embodiment of the first aspect of the present invention, a hub motor includes a central shaft and a housing assembly, a stator assembly, a rotor assembly and a gear assembly connected to the central shaft. The housing assembly and the rotor assembly are both supported on the central shaft by bearings. The stator assembly includes a stator core and a winding. The stator core has a certain thickness and forms a closed yoke. A plurality of teeth are provided on the outer periphery of the yoke. The winding is wound around the teeth and uses aluminum wire. The rotor assembly has a permanent magnet, and the material of the permanent magnet is ferrite. The rotor assembly and the housing assembly are transmission-connected via the gear assembly.

[0006] The in-wheel motor according to the first embodiment of the present invention has at least the following beneficial effects: the rotor assembly of the in-wheel motor drives the housing assembly to rotate via the gear assembly, and the housing assembly and the wheel of the electric vehicle are integrated into a structure, enabling the electric vehicle to travel. The stator core includes a yoke and multiple teeth on the outer periphery of the yoke. The winding uses aluminum wire instead of copper conductors. The permanent magnets of the rotor assembly use ferrite material instead of expensive rare earth permanent magnets, which helps reduce the manufacturing cost of the in-wheel motor.

[0007] According to some embodiments of the first aspect of the present invention, the tooth portion is configured as straight teeth.

[0008] According to some embodiments of the first aspect of the present invention, the tooth portion is a tooth-shoe-free structure, the stator core is connected to a limit frame, and the limit frame is used to limit the radial position of the winding relative to the tooth portion.

[0009] According to some embodiments of the first aspect of the present invention, the limiting frame includes a mounting portion and a limiting portion, the mounting portion is connected to the stator assembly, the limiting portion corresponds one-to-one with the tooth portion, the limiting portion includes two fork rods, the spacing between the two fork rods is adapted to the width of the tooth portion, and the fork rods abut against the outer end of the winding.

[0010] According to some embodiments of the first aspect of the present invention, the housing assembly has a main housing, the rotor assembly is provided with a first retaining ring facing the main housing, the main housing is provided with a second retaining ring facing the rotor assembly, a grease sealing cavity is formed between the rotor assembly and the main housing, and the gear assembly is located in the grease sealing cavity.

[0011] According to some embodiments of the first aspect of the present invention, along the axial direction of the central shaft, the first retaining ring and the second retaining ring are at least partially staggered.

[0012] According to some embodiments of the first aspect of the present invention, along the axial direction of the central axis, the length dimension of the staggered first retaining ring and the second retaining ring is L, and L≥0.1 mm.

[0013] According to some embodiments of the first aspect of the present invention, along the axial direction of the central shaft, the first retaining ring and the second retaining ring are flush.

[0014] According to some embodiments of the first aspect of the present invention, along the radial direction of the central shaft, the second retaining ring is located between the first retaining ring and the central shaft.

[0015] According to some embodiments of the first aspect of the present invention, the inner wall diameter of the first retaining ring is D1, and the outer wall diameter of the second retaining ring is D2, satisfying 1mm≤D1-D2≤4mm.

[0016] According to some embodiments of the first aspect of the present invention, along the radial direction of the central shaft, the first retaining ring is located between the second retaining ring and the central shaft.

[0017] According to some embodiments of the first aspect of the present invention, an accommodating groove is provided on an end surface of the first retaining ring facing the main housing, and a portion of the second retaining ring is located in the accommodating groove.

[0018] According to some embodiments of the first aspect of the present invention, the rotor assembly includes a rotor overmolded part, and the rotor overmolded part is provided with a plurality of circumferentially evenly distributed heat dissipation blades, and the heat dissipation blades face the stator assembly.

[0019] According to some embodiments of the first aspect of the present invention, the rotor overmolded component is provided with a plurality of circumferentially evenly distributed guide holes, and the guide holes are located between two adjacent heat dissipation blades.

[0020] According to some embodiments of the first aspect of the present invention, the first retaining ring is provided on the rotor overmolded component, and the plurality of guide holes are arranged on the outside of the first retaining ring.

[0021] According to some embodiments of the first aspect of the present invention, along the radial direction of the central axis, the positions of the windings and the guide holes correspond to each other.

[0022] According to some embodiments of the first aspect of the present invention, the cross-section of the aluminum wire is non-circular.

[0023] According to some embodiments of the first aspect of the present invention, the cross-section of the aluminum wire is square.

[0024] An electric vehicle according to an embodiment of the second aspect of the present invention comprises the hub motor described in the embodiment of the first aspect.

[0025] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments with reference to the accompanying drawings, in which:

[0027] Figure 1 is a cross-sectional view of a hub motor according to some embodiments of the present invention;

[0028] Figure 2 Schematic diagram of the structure of the stator assembly in some embodiments of the present invention;

[0029] Figure 3 Schematic diagram of the structure of the stator core and winding in some embodiments of the present invention;

[0030] Figure 4 Schematic diagram of the structure of the limiting frame in some embodiments of the present invention;

[0031] Figure 5 Schematic diagram of the structure of the stator core in some embodiments of the present invention;

[0032] Figure 6 is an exploded schematic diagram of a hub motor in some embodiments of the present invention;

[0033] Figure 7 for Figure 1 A partial enlarged view of point A in the middle;

[0034] Figure 8 Partial view of the cooperation between the first retaining ring and the second retaining ring in other embodiments of the present invention Figure 1 ;

[0035] Figure 9Partial view of the cooperation between the first retaining ring and the second retaining ring in other embodiments of the present invention Figure 2 ;

[0036] Figure 10 Schematic diagram of the structure of the rotor assembly in some embodiments of the present invention Figure 1 ;

[0037] Figure 11 Schematic diagram of the structure of the rotor assembly in some embodiments of the present invention Figure 2 ;

[0038] Figure 12 Schematic diagram of an exploded view of a rotor assembly in some embodiments of the present invention.

[0039] The accompanying figures are as follows:

[0040] Middle shaft 100, bearing 110;

[0041] Housing assembly 200, grease sealing cavity 201, main housing 210, second retaining ring 211, auxiliary housing 220, rim 230;

[0042] Stator assembly 300, winding 310, stator core 320, teeth 321, yoke 322, limit frame 330, fork rod 331;

[0043] Rotor assembly 400, rotor overmolded part 410, rotor overmolded part 410, first retaining ring 411, receiving groove 4111, heat dissipation fan blade 412, inner sleeve 413, guide hole 414, bearing seat 420, yoke 430, permanent magnet 440;

[0044] Gear assembly 500 , sun gear 510 , planet gears 520 , planet carrier 530 , outer ring gear 540 . DETAILED DESCRIPTION

[0045] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0046] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0047] In the description of the present invention, if there is a description of first and second, it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0048] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0049] In related technologies, electric vehicles use hub motors as power components. The outer rotor and rim of the hub motor are an integrated structure. The design of the hub motor pursues the integration of the power system, transmission system and braking system. Some hub motors are equipped with gear reducers. The high-speed rotation of the gears can easily throw off the grease, resulting in insufficient grease on the gear surface. One of the reasons why such hub motors have not been used in large quantities is that the gear reducer has a high risk of gear wear and failure due to poor lubrication, which leads to poor reliability of the hub motor with a gear reducer, affecting the driving stability of the electric vehicle.

[0050] like Figures 1 to 6 As shown, an embodiment of the first aspect of the present invention proposes a hub motor for an electric vehicle, wherein the hub motor includes a central axis 100 and a housing assembly 200, a stator assembly 300, a rotor assembly 400 and a gear assembly 500 connected to the central axis 100. The central axis 100 is connected to the frame of the electric vehicle and serves as an installation base. The housing assembly 200 includes a main housing 210, a sub-housing 220 and a rim 230. The main housing 210 and the sub-housing 220 are disposed at both ends of the rim 230. The main housing 210 and the sub-housing 220 are fixedly connected to both ends of the rim 230 by screws. Three bearings 110 are installed on the central axis 100. The main housing 210, the sub-housing 220 and the rotor assembly 400 are each connected to a bearing 110 and can rotate relative to the central axis 100.

[0051] Reference Figures 2 to 5 The stator assembly 300 includes a winding 310, a stator core 320, and a limit frame 330. The stator core 320 is generally cut from silicon steel sheets. The cut silicon steel sheets are processed into a wound stator core 320. In order to improve the utilization rate of the silicon steel sheets, it is necessary to design the splicing and cutting method in advance when cutting. If the tooth portion 321 of the stator core 320 is provided with a tooth boot, when cutting the stator core, the splicing and cutting method must be designed according to the tooth boot. However, no matter how it is optimized, in the case of tooth boots, the material utilization rate of the silicon steel sheet can only reach 70% at most, and it is difficult to improve further. The stator core 320 of the embodiment of the present invention adopts a tooth portion 321 without a tooth boot, optimizes the splicing and cutting method, and thereby improves the material utilization rate of the silicon steel sheet.

[0052] It is understandable that the tooth portion 321 is configured as a straight tooth shape, and the winding 310 does not need to be wound on the tooth portion 321. The winding can be completed externally using tooling, which provides a large operating space and can effectively improve the winding slot full rate. In addition, the winding 310 uses an aluminum wire with a non-circular cross-section, such as an aluminum wire with a square cross-section, while the tooth portion 321 uses a straight tooth structure, such as the cross-section of the tooth portion 321 is also square. The aluminum wire of the winding 310 matches the shape of the tooth portion 321, and the aluminum wire fits tightly against the outer wall of the tooth portion 321, making the arrangement of the aluminum wire more compact, thereby improving the winding slot full rate of the stator assembly 300. While the volume of the stator assembly 300 remains unchanged, the power density and efficiency of the hub motor are improved. The hub motor is used in electric vehicles, which helps to improve the endurance of electric vehicles. In addition, the winding 310 uses aluminum wire instead of copper conductor, which helps to reduce the manufacturing cost of the hub motor.

[0053] It should be noted that the retaining frame 330 includes a mounting portion and a retaining portion. The mounting portion is used to securely connect to the stator assembly 300, and the retaining portion is used to radially limit the windings 310. The retaining portions are identical in number to the number of windings 310, and their positions correspond one-to-one. The retaining portions are used to limit the windings 310, replacing the toothed boots. The mounting portion and the stator assembly 300 can be fixedly connected or removably connected. Fixed connections can be achieved by welding or riveting, while removable connections can be achieved by screws or snap-fit ​​structures, etc.

[0054] Reference Figure 5 The stator core 320 includes a yoke 322 and a plurality of teeth 321 without tooth boots. The stator core 320 has a certain thickness and forms a closed yoke 322. The plurality of teeth 321 are evenly distributed along the circumference of the yoke 322. The teeth 321 use straight teeth to facilitate the installation of the winding 310. The teeth 321 without tooth boots means that the side walls of the teeth 321 do not have a structure extending outward to define the winding 310. Therefore, Figure 4 As shown, each limiting portion of the limiting frame 330 has two parallel fork rods 331, and the spacing between the two fork rods 331 is adapted to the width of the tooth portion 321, so that the space between the two fork rods 331 can accommodate the tooth portion 321. The fork rods 331 abut against the outer end surface of the winding 310, and there are two force points acting on the winding 310 to reliably limit the winding 200 and fix the winding 310 in the radial direction.

[0055] It is understandable that a connecting rod (not shown in the figure) can be set between the two fork rods 331. The connecting rod is set perpendicular to the fork rod 331. After assembly, the connecting rod also abuts against the outer end face of the winding 310 to help limit the winding 310 and further improve reliability.

[0056] Reference Figure 1 and Figure 6 The gear assembly 500 includes a sun gear 510, three planetary gears 520, a planetary carrier 530 and an outer ring gear 540. The sun gear 510 is fixedly connected to the rotor assembly 400, the planetary carrier 530 is fixedly connected to the central shaft 100, the three planetary gears 520 are rotatably connected to the planetary carrier 530, the outer ring gear 540 is fixedly connected to the main housing 210, and the planetary gears 520 are simultaneously engaged with the sun gear 510 and the outer ring gear 540. The rotor assembly 400 drives the sun gear 510 to rotate, the sun gear 510 drives the three planetary gears 520 to rotate, and the three planetary gears 520 then drive the outer ring gear 540 and the main housing 210 to rotate. The main housing 210 drives the rim 230 to rotate. The rim 230 belongs to the wheel of the electric vehicle, so the hub motor bracket drives the wheel to rotate to realize the driving of the electric vehicle. In addition, the planetary gear 520 is a double gear, which realizes two-stage transmission deceleration through the planetary gear 520, reduces the rotation speed of the rim 230, and improves the output torque of the hub motor at the same time, which is beneficial to speeding up the electric vehicle.

[0057] It can be understood that the gear assembly 500 is located between the rotor assembly 400 and the main housing 210. Therefore, the rotor assembly 400 and the main housing 210 cooperate to form a grease sealing chamber 201, and the gear assembly 500 is arranged in the grease sealing chamber 201. The grease sealing chamber 201, on the one hand, accommodates the gear assembly 500 to prevent the gear assembly 500 from being exposed, and on the other hand, accommodates grease so that the surfaces of the sun gear 510, the three planetary gears 520 and the outer ring gear 540 can be coated with grease to provide sufficient lubrication and reduce wear.

[0058] It is understandable that, considering that the grease will be thrown away due to the centrifugal force during the high-speed rotation of the sun gear 510 and the three planetary gears 520, which will lead to the problem of insufficient lubrication of the sun gear 510 and the three planetary gears 520, a first retaining ring 411 is provided on the rotor assembly 400, and a second retaining ring 211 is provided on the main housing 210. The first retaining ring 411 faces the main housing 210, and the second retaining ring 211 faces the rotor assembly 400. The first retaining ring 411 and the second retaining ring 211 form the side wall of the grease sealing cavity 201, which plays a role in preventing the grease from leaking out. In the axial direction of the central shaft 100, the first retaining ring 411 and the second retaining ring 211 are staggered, which can block the grease that is thrown away and prompt the grease to remain in the grease sealing cavity 201, thereby ensuring that the gear assembly 500 has sufficient lubrication. In the radial direction of the central shaft 100, the first retaining ring 411 and the second retaining ring 211 are close to each other but not in contact, and do not affect the independent rotation of the rotor assembly 400 and the main housing 210. When the in-wheel motor is in operation, the stator assembly of the in-wheel motor rotates the rotor assembly 400 through electromagnetic force. The rotor assembly 400 drives the housing assembly 200 to rotate via the gear assembly 500. The housing assembly 200 then drives the wheels of the electric vehicle via the rim 230, thereby enabling the electric vehicle to travel. The gear assembly 500 is located within the grease sealing chamber 201 between the rotor assembly 400 and the main housing 210. Grease is stored within the grease sealing chamber 201 and coated on the surface of the gear assembly 500 to provide lubrication. The first retaining ring 411 of the rotor assembly 400 and the second retaining ring 211 of the main housing 210 are axially staggered to form a blocking structure that prevents the grease from being ejected from the grease sealing chamber 201. The grease remains within the grease sealing chamber 201 to lubricate the gear assembly 500, improving the lubrication effect and avoiding reliability issues such as wear and failure of the gear assembly 500 due to insufficient lubrication. This improves the operational reliability of the in-wheel motor and the reliability of the electric vehicle.

[0059] Reference Figure 7 It can be understood that in the axial direction of the central shaft 100, the first retaining ring 411 and the second retaining ring 211 are staggered, and the staggered length dimension is defined as L, where L is the overlapping length of the first retaining ring 411 and the second retaining ring 211, and L is set to be ≥ 0.1 mm. Considering that the first retaining ring 411 and the second retaining ring 211 are not in contact, the staggered length dimension L is set to 0.1 mm or above to form an effective barrier to prevent grease from leaking from the gap between the first retaining ring 411 and the second retaining ring 211.

[0060] It can be understood that, in the axial direction of the central shaft 100, the first retaining ring 411 and the second retaining ring 211 may not be staggered, and the two may be arranged flush, that is, the end face of the first retaining ring 411 and the end face of the second retaining ring 211 are located in the same plane, which can also block the grease that is thrown away, and promote the grease to remain in the grease sealing cavity 201, thereby ensuring that the gear assembly 500 has sufficient lubrication.

[0061] Reference Figure 7 It is understood that in the radial direction of the central shaft 100, the first retaining ring 411 is located outside the second retaining ring 211, and the second retaining ring 211 is closer to the central shaft 100. After the grease is thrown off, it first contacts the second retaining ring 211 and then contacts the first retaining ring 411. Moreover, the first retaining ring 411 and the second retaining ring 211 are staggered, which can limit the grease that is thrown off and keep it in the grease sealing cavity 201.

[0062] Reference Figure 1 It can be understood that the inner wall diameter of the first retaining ring 411 is defined as D1, and the outer wall diameter of the second retaining ring 211 is defined as D2. Considering that when the hub motor is running, the rotor assembly 400 and the main housing 210 both rotate at high speed, and the rotation speeds of the rotor assembly 400 and the main housing 210 are different, D1 and D2 satisfy (D1-D2) / 2≥0.5mm to ensure that the first retaining ring 411 and the second retaining ring 211 do not cause friction and collision during rotation. In addition, D1 and D2 satisfy (D1-D2) / 2≤2.0mm to provide effective blocking, which is beneficial to reducing the leakage of grease from the grease sealing cavity 201. After calculation, it is set to 1mm≤D1-D2≤4mm. The gap between the first retaining ring 411 and the second retaining ring 211 can prevent grease leakage without generating interference friction.

[0063] Reference Figure 8 It is understood that, in the radial direction of the central shaft 100, the second retaining ring 211 may be located outside the first retaining ring 411, with the first retaining ring 411 being closer to the central shaft 100. After the grease is thrown off, it first contacts the first retaining ring 411 and then the second retaining ring 211. Moreover, the first retaining ring 411 and the second retaining ring 211 are staggered, which can limit the grease that is thrown off and keep it in the grease sealing cavity 201.

[0064] Reference Figure 8 As will be understood, the first retaining ring 411 has two side plates, forming a receiving groove 4111 between the two side plates. The receiving groove 4111 is located on the end surface of the first retaining ring 411 facing the main housing 210. Because the first and second retaining rings 411 and 211 are arranged in an alternating pattern, a portion of the second retaining ring 211 extends into the receiving groove 4111. The first and second retaining rings 411 and 211 cooperate to form a double-layer barrier, more effectively blocking grease from being ejected. Furthermore, the second retaining ring 211 partially extends into the receiving groove 4111, forming a continuously curved gap between the first and second retaining rings 411 and 211, similar to a labyrinth seal structure, which helps reduce the chance of grease leakage.

[0065] Reference Figures 10 to 12It can be understood that the main component of the rotor assembly 400 is the rotor overmolded part 410. The rotor overmolded part 410 integrally wraps the yoke 430 and the permanent magnet 440 during the injection molding process. In addition, the bearing seat 420 and the rotor overmolded part 410 are also an integrally molded structure. The bearing seat 420 is located at the center of the rotor overmolded part 410. The inner wall of the bearing seat 420 forms a bearing chamber to cooperate with the bearing 110. In order to improve the stability of the connection, the outer wall of the bearing seat 420 has a plurality of circumferentially distributed bosses. After injection molding, the bosses are embedded in the rotor overmolded part 410, which improves the structural strength and is conducive to the transmission of torque. Considering that the rotor overmolded part 410 is an injection molded part, the first retaining ring 411 is set on the rotor overmolded part 410 to facilitate manufacturing and reduce costs. The rotor assembly 400 adopts an integrated structure, and uses the rotor overmolded part 410 to wrap the yoke 430 and the permanent magnet 440 to achieve fixation, thereby preventing the permanent magnet 440 from falling off, improving the reliability of the rotor assembly 400, and facilitating the service life of the hub motor.

[0066] It is understandable that the permanent magnet 440 is made of ferrite material, which is low-cost and does not require the use of expensive rare earth permanent magnet materials, thereby reducing the manufacturing cost of the hub motor.

[0067] Reference Figure 1 and Figure 6 It is understood that the rotor overmolded part 410 is provided with a plurality of heat dissipation blades 412, which are evenly distributed along the circumference of the rotor overmolded part 410. The rotor overmolded part 410 is provided with an inner sleeve 413, and the bearing seat 420 is connected to the inner wall of the inner sleeve 413. The heat dissipation blades 412 extend radially from the outer wall of the inner sleeve 413. Inside the hub motor, the heat dissipation blades 412 face the stator assembly 300, and the outer edges of the heat dissipation blades 412 are relatively low to avoid the windings 310 of the stator assembly 300. When the rotor assembly 400 rotates at high speed, the multiple heat dissipation blades 412 drive the airflow, thereby removing the heat generated by the windings 310, helping to reduce the temperature and prevent over-temperature shutdown problems.

[0068] Reference Figures 6 to 8 It is understood that the rotor overmolded part 410 is further provided with a plurality of guide holes 414, which are evenly distributed along the circumference of the rotor overmolded part 410, and each guide hole 414 is arranged between the extension lines of two adjacent heat dissipation blades 412. For example, the guide holes 414 may correspond to the heat dissipation blades 412 one by one, or the number of the guide holes 414 may be half of the number of the heat dissipation blades 412. Figure 1As shown, when the rotor assembly 400 rotates at high speed, multiple heat dissipation blades 412 are used to drive the air flow. The guide holes 414 serve as channels for the air flow, connecting the two sides of the rotor overmolded component 410. The air flow flows to the inner cavity of the shell assembly 200. The main shell 210 and the auxiliary shell 220 of the shell assembly 200 are metal parts, such as aluminum alloy parts, with greater structural strength and excellent heat transfer performance. The air flow contacts the main shell 210 and the auxiliary shell 220, and dissipates heat to the external space through the main shell 210 and the auxiliary shell 220.

[0069] The rotor assembly 400 rotates at high speed, creating an air circulation loop within the in-wheel motor using the heat dissipation blades 412 and guide holes 414. This improves the motor's internal air convection, effectively dissipating heat generated by the windings 310, enhancing the motor's heat dissipation performance and reducing the motor's temperature rise. This ensures stable output efficiency and meets the motor's load requirements. Furthermore, the heat dissipation blades 412 serve as reinforcement ribs, increasing the overall structural strength and rigidity of the rotor assembly 400 and enhancing reliability.

[0070] Reference Figure 11 As will be appreciated, the first retaining ring 411 is integrally formed on the rotor overmolding 410, and multiple guide holes 414 are arranged on the outside of the first retaining ring 411. Air flowing through the guide holes 414 does not enter the grease sealing cavity 201, preventing the airflow from affecting the grease. Furthermore, the guide holes 414 are located at the outer edge of the rotor overmolding 410, allowing air to quickly flow to the main housing 210, facilitating heat dissipation.

[0071] Reference Figure 1 It can be understood that, in the radial direction of the central axis 100, the distance between the winding 310 and the central axis 100 is substantially equal to the distance between the guide hole 414 and the central axis 100, and the positions of the two correspond, so that the heat emitted by the winding 310 is quickly carried away by the airflow passing through the guide hole 414, which helps to improve the heat dissipation effect of the winding 310.

[0072] The electric vehicle of the second embodiment of the present invention includes the hub motor of the first embodiment. The hub motor includes a central axis 100 and a shell assembly 200 connected to the central axis 100, a stator assembly 300, a stator assembly 300 and a gear assembly 500. The stator assembly 300 includes a winding 310, a stator core 320 and a limit frame 330. The stator core 320 adopts a straight tooth portion 321. The winding 310 does not need to be wound on the tooth portion 321, and the winding can be completed externally using tooling. The operating space is large and the slot fill rate can be effectively improved. In addition, the winding 310 uses an aluminum wire with a non-circular cross-section, such as an aluminum wire with a square cross-section. The aluminum wire of the winding 310 matches the shape of the tooth portion 321, and the aluminum wire fits tightly against the outer wall of the tooth portion 321. The aluminum wire is arranged more densely, thereby improving the winding slot fill rate of the stator assembly 300. While the volume of the stator assembly 300 remains unchanged, the power density and efficiency of the hub motor are improved. The application of the hub motor in electric vehicles helps to improve the endurance of the electric vehicles.

[0073] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the spirit of the present invention.

Claims

1. Hub motor, characterized in that: include: central axis; a housing assembly supported on the central shaft via bearings; A stator assembly is fixedly connected to the central shaft, and the stator assembly includes a stator core and a winding. The stator core has a closed yoke, and a plurality of teeth are provided on the outer periphery of the yoke. The winding is wound on the teeth. The winding adopts an aluminum wire, and the cross-section of the aluminum wire is square. The teeth are arranged as straight teeth and have no tooth shoe structure. The stator core is connected to a limiting frame, and the limiting frame is used to limit the radial position of the winding relative to the teeth. The limiting frame includes a mounting portion and a limiting portion, and the mounting portion is connected to the stator assembly. The limiting portion corresponds to the teeth one by one. The limiting portion includes two fork rods, and the spacing between the two fork rods is adapted to the width of the teeth. The fork rods abut against the outer ends of the windings. a rotor assembly supported on the central shaft via bearings, the rotor assembly comprising a permanent magnet made of ferrite; a gear assembly connected to the central shaft; In which, the rotor assembly and the housing assembly are transmission-connected via the gear assembly, the housing assembly has a main housing, the rotor assembly is provided with a first retaining ring facing the main housing, the main housing is provided with a second retaining ring facing the rotor assembly, a grease sealing cavity is formed between the rotor assembly and the main housing, the gear assembly is located in the grease sealing cavity, along the axial direction of the central axis, the first retaining ring and the second retaining ring are at least partially staggered, along the radial direction of the central axis, the second retaining ring is located between the first retaining ring and the central axis, the inner wall diameter of the first retaining ring is D1, the outer wall diameter of the second retaining ring is D2, satisfying 1mm≤D1-D2≤4mm.

2. The hub motor according to claim 1, characterized in that: Along the axial direction of the central axis, the length dimension of the staggered first retaining ring and the second retaining ring is L, and L≥0.1 mm.

3. The hub motor according to claim 1, characterized in that: Along the axial direction of the central shaft, the first retaining ring and the second retaining ring are flush.

4. The hub motor according to claim 1, characterized in that: An accommodating groove is provided on the end surface of the first retaining ring facing the main housing, and a portion of the second retaining ring is located in the accommodating groove.

5. The hub motor according to claim 1, characterized in that: The rotor assembly includes a rotor overmolded part, and the rotor overmolded part is provided with a plurality of circumferentially evenly distributed heat dissipation blades, and the heat dissipation blades face the stator assembly.

6. The hub motor according to claim 5, characterized in that: The rotor overmolded component is provided with a plurality of guide holes uniformly distributed in the circumferential direction, and the guide holes are located between two adjacent heat dissipation blades.

7. The hub motor according to claim 6, characterized in that: The first retaining ring is provided on the rotor overmolded component, and the plurality of guide holes are arranged on the outer side of the first retaining ring.

8. The hub motor according to claim 6, characterized in that: Along the radial direction of the central axis, the positions of the windings and the guide holes correspond to each other.

9. An electric vehicle, characterized in that The invention comprises the hub motor according to any one of claims 1 to 8.

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