A hub motor for electric bicycles

Abstract

This application relates to a hub motor for electric bicycles, comprising a hub housing, a central shaft, and a motor assembly. The central shaft passes through the hub housing. The motor assembly includes a rotor disk rotatably sleeved on the outer surface of the central shaft. The rotor disk is connected to the hub housing via a transmission mechanism. Permanent magnets are disposed on the outer periphery of the rotor disk, and multiple magnets are evenly and equidistantly arranged on its end face. A stator core is fixedly mounted on the central shaft, and an insulating frame is fitted over the stator core. Multiple stator windings are evenly arranged circumferentially on the insulating frame, and the winding axes of the multiple stator windings are parallel to the axis of the central shaft. This application improves the stability of the detection signal of the detection element and extends the service life of the hub motor.

Description

Technical Field

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

[0002] Electric bicycles, as a convenient and environmentally friendly means of transportation, have been widely used in short-distance travel. As the core power component of electric bicycles, the hub motor integrates the drive unit into the wheel hub, eliminating intermediate transmission structures such as chains or gears. It has the advantages of high transmission efficiency and compact structure, and has become the mainstream drive solution for modern electric bicycles.

[0003] In existing technologies, the magnetic field generated between the stator and rotor disk of the hub motor used in electric bicycles is usually perpendicular to the motor's rotation axis. In order to control the motor, a detection element is usually installed inside the motor to detect the position of the rotor disk's magnetic poles in real time, so as to obtain the magnetic field change signal and feed it back to the controller. The most common detection element is the Hall sensor.

[0004] However, the magnetic field direction perpendicular to the rotation axis often leads to unstable detection signals of Hall sensors in practical applications. Specifically, the sensitive direction of Hall sensors is usually the axial direction of the rotation axis, which is perpendicular to the magnetic field direction in existing hub motors. Therefore, the magnetic field component actually detected by the Hall sensor is often less than the actual magnetic field strength, resulting in a lower fundamental amplitude of the detection signal and a reduced ability to distinguish subtle changes in the magnetic field. The Hall sensor has difficulty accurately capturing the critical state of these fluctuations and is prone to signal jumps or delays.

[0005] The aforementioned problem of unstable Hall sensor detection signals directly affects the control board's judgment of the motor rotor disk position, causing the motor to be in an unstable working state for a long time, aggravating the wear of internal motor components, shortening the motor's service life, and even potentially causing motor failure due to inaccurate control, posing a potential threat to riding safety. Summary of the Invention

[0006] In order to improve the stability of the detection signal of the detection element and extend the service life of the hub motor, this application provides a hub motor for electric bicycles.

[0007] The hub motor for electric bicycles provided in this application adopts the following technical solution: A hub motor for an electric bicycle includes a hub housing, a central shaft, and a motor assembly. The central shaft passes through the hub housing and rotatably engages with it. The motor assembly includes a rotor disk rotatably sleeved on the outer surface of the central shaft. The rotor disk is connected to the hub housing via a transmission mechanism. A permanent magnet is disposed on the outer periphery of the rotor disk, and multiple magnets are evenly and equidistantly arranged on its end face. A stator core is fixedly disposed on the central shaft. An insulating frame is sleeved on the stator core. Multiple stator windings are evenly arranged circumferentially on the insulating frame. The winding axes of the multiple stator windings are parallel to the axis of the central shaft. An MR plate is disposed inside the hub housing, and a detection element is disposed on the MR plate. The sensing end of the detection element faces the surface of the permanent magnet.

[0008] By adopting the above technical solution, the stator winding is energized. Since the stator winding is wound around the stator core with the central axis in the direction of the axis, the magnetic field generated by the magnet cutting the stator winding is parallel to the direction of the central axis. It cooperates with the permanent magnet to form an axial magnetic field, so that the magnetic field direction of the hub motor is consistent with the sensitive direction of the detection element. This increases the number of magnetic field components that the detection element can detect, improves the basic amplitude of the detection signal, and thus improves the stability of the detection signal and extends the service life of the hub motor.

[0009] Optionally, a core cover is provided inside the hub housing, the core cover is placed on the outer periphery of the motor assembly, the central shaft passes through the core cover through a flat key, the core cover includes a core cover and a core shell that overlap, the stator core is detachably connected to the core cover by a plurality of countersunk bolts, and the MR plate is detachably connected to the core cover by connecting screws.

[0010] By adopting the above technical solution, the core cover protects the internal motor components, reduces the interference of external impurities on the motor components, and thus extends the overall service life of the motor. At the same time, the stator core and MR plate can be detachably connected to the core cover, making it convenient for workers to maintain and replace the motor components, reducing maintenance costs and difficulty.

[0011] Optionally, the transmission mechanism includes an internal gear ring, a first-stage reduction assembly, and a second-stage reduction assembly. The internal gear ring is fixedly disposed inside the movement housing. The power input end of the first-stage reduction assembly is connected to the rotor disk, and the power output end is connected to the power input end of the second-stage reduction assembly. The power output end of the second-stage reduction assembly is connected to the hub housing.

[0012] By adopting the above technical solution, the stator winding drives the rotor disc to rotate after being energized. At this time, the first-stage reduction assembly reduces the high-speed rotation of the rotor disc and transmits it to the second-stage reduction assembly. Then, the second-stage reduction assembly reduces this part of the power again and transmits it to the hub housing, so that a large transmission ratio is formed between the rotor disc and the hub housing, thereby increasing the output torque of the hub housing and meeting the power requirements of electric bicycles for low speed and high torque.

[0013] Optionally, the first-stage reduction assembly includes a first-stage sun gear base, a first-stage sun gear, and a first-stage planetary carrier. The first-stage sun gear base is coaxially arranged with the rotor disk. The first-stage planetary carrier is provided with multiple first-stage planetary gears, all of which are located between the tooth surfaces of the first-stage sun gear and the internal gear ring and simultaneously mesh with both the first-stage sun gear and the internal gear ring. The second-stage reduction assembly includes a second-stage sun gear, a second-stage planetary carrier, and an output ring. The second-stage sun gear meshes with the internal tooth surface of the first-stage planetary carrier. The second-stage planetary carrier is provided with multiple second-stage planetary gears, all of which are located between the tooth surfaces of the second-stage sun gear and the internal gear ring and simultaneously mesh with both the second-stage sun gear and the internal gear ring. The output ring is rotatably sleeved on the central shaft. The second-stage planetary carrier and the hub housing are both connected to the output ring.

[0014] By adopting the above technical solution, when the rotor disk rotates, it drives the first-stage sun gear base to rotate. The first-stage sun gear base drives the first-stage sun gear to rotate, thereby driving multiple first-stage planetary gears to rotate around their own axes while revolving along the tooth surface of the internal gear ring. The revolution of the first-stage planetary gears drives the first-stage planetary carrier to rotate synchronously. The first-stage planetary carrier drives the second-stage sun gear to rotate. The rotation of the second-stage sun gear drives multiple second-stage planetary gears to revolve along the tooth surface of the internal gear ring while rotating on their own axes, driving the second-stage planetary carrier to rotate synchronously. The second-stage planetary carrier drives the hub housing to rotate through the output ring.

[0015] Optionally, a ventilation groove is provided on the central shaft, the ventilation groove extends into the interior of the hub housing, a plurality of air inlets are evenly provided on the circumferential side of the mechanism cover, a partition is provided inside the mechanism housing, a plurality of air vents are evenly provided on the circumferential side of the partition, an air vent groove is provided on the mechanism housing that communicates with the air vents, and a plurality of air outlets are provided on the side of the hub housing near the mechanism cover.

[0016] By adopting the above technical solution, during the operation of the hub motor, external air enters the hub housing through the ventilation slots. The air flows over the surface of the motor components, absorbs heat, and forms hot air. Subsequently, the hot air flows through multiple air inlets and multiple air channels to the gap between the outer surface of the core housing and the inner wall of the hub housing, and is finally discharged through multiple air outlets. This achieves effective heat dissipation of the motor components inside the core housing, reduces the possibility of performance degradation or component damage caused by high temperature, and thus extends the service life of the motor.

[0017] Optionally, the rotor disk has multiple receiving slots, which are parallel to the radial direction of the rotor disk. Each receiving slot is slidably connected to a heat sink, and a tension spring is provided in the receiving slot. The force exerted by the tension spring on the heat sink is opposite to the direction of the centrifugal force on the heat sink.

[0018] By adopting the above technical solution, when the rotor disk rotates, the heat sink tends to slide outward under the action of centrifugal force, while the tension spring provides a counterforce to form a balance, so that the extension length of the heat sink changes dynamically with the rotor disk speed. When the speed increases, the centrifugal force on the heat sink is greater than the elastic force of the tension spring, and the heat sink extends out of the receiving groove, which increases the contact area between the rotor disk and the air, thereby improving the convective heat dissipation efficiency. When the speed decreases, the tension spring pulls the heat sink back, reducing wind resistance and thus reducing energy consumption.

[0019] Optionally, the plurality of receiving slots are distributed in a spiral pattern along the axial direction of the rotor disk.

[0020] By adopting the above technical solution, when the rotor disk rotates, the spirally distributed heat sink can guide the airflow along the spiral trajectory, thereby increasing the contact time and contact area between the airflow and the heat sink. At the same time, it can promote the air to form a directional circulation in the rotor disk axis, accelerate the hot air to flow out through the air inlet and air slot, thereby further improving the convective heat dissipation efficiency.

[0021] Optionally, a limiting groove is provided on the inner sidewall of the receiving groove, and a rotating block is rotatably connected to the heat sink. The rotating block is rolled in the limiting groove. When the rotating block abuts against the end of the limiting groove away from the central axis, a gap is left between the heat sink and the inner sidewall of the mechanism housing.

[0022] By adopting the above technical solution, the length of the limiting slot controls the maximum extension of the heat sink, ensuring that there is always a gap between the heat sink and the inner wall of the core housing, thereby avoiding frictional heat generation between the heat sink and the core housing and reducing the heat dissipation burden on the inside of the core housing.

[0023] In summary, this application includes at least one of the following beneficial technical effects: This application arranges the stator winding axis parallel to the central axis. Since the stator winding is wound on the stator core in the direction of the central axis, the magnetic field generated by the magnet cutting the stator winding is parallel to the direction of the central axis. This magnetic field, in conjunction with the permanent magnet, forms an axial magnetic field, making the magnetic field direction of the hub motor consistent with the sensitive direction of the detection element. This increases the number of magnetic field components that the detection element can detect, improves the basic amplitude of the detection signal, and thus enhances the stability of the detection signal and improves the service life of the hub motor. This application connects the hub housing and the rotor disc through a transmission mechanism. The transmission mechanism transmits power to the hub housing in a secondary reduction mode, so that a large transmission ratio is formed between the rotor disc and the hub housing, thereby increasing the output torque of the hub housing and meeting the power requirements of electric bicycles for low speed and high torque. This application achieves effective heat dissipation for the motor components inside the mechanism housing by creating ventilation slots, air inlets, air outlets, air channels, and air outlets. External air enters the hub housing through the ventilation slots, flows over the surface of the motor assembly, absorbs heat, and forms hot air. The hot air then flows through multiple air inlets and air channels to the gap between the outer surface of the mechanism housing and the inner wall of the hub housing, and is finally discharged through multiple air outlets.

[0024] This application incorporates a tension spring and a heat sink. When the rotor disk rotates, the heat sink tends to slide outward under the action of centrifugal force, while the tension spring provides a counterforce to form a balance, so that the extension length of the heat sink dynamically changes with the rotor disk speed. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of this application.

[0026] Figure 2 This is a cross-sectional view of the hub housing in Embodiment 1 of this application.

[0027] Figure 3 This is a cross-sectional view of the stator core and rotor disk in Embodiment 1 of this application.

[0028] Figure 4 This is an exploded view of the primary deceleration assembly and the secondary deceleration assembly in Embodiment 1 of this application.

[0029] Figure 5 This is a schematic diagram of the structure of Embodiment 2 of this application.

[0030] Figure 6 This is a schematic diagram of the mechanism cover in Embodiment 2 of this application.

[0031] Figure 7 This is a cross-sectional view of the rotor disk in Embodiment 2 of this application.

[0032] Figure 8 This application Figure 7 Enlarged view of point A in the middle.

[0033] Explanation of reference numerals in the attached drawings: 1. Hub housing; 2. Central shaft; 21. Ventilation slot; 101. Tower base; 102. Disc brake end cap; 103. Air outlet; 3. Mechanism cover; 31. Mechanism cover; 311. Air inlet; 32. Mechanism housing; 321. Air duct; 33. Partition plate; 331. Air outlet; 4. Motor assembly; 41. Stator core; 42. Insulating frame; 43. Rotor disc; 44. Permanent magnet; 45. Magnet; 46. M R plate; 5. Transmission mechanism; 51. Internal gear ring; 52. First-stage reduction assembly; 521. First-stage sun gear base; 522. First-stage sun gear; 523. First-stage planetary carrier; 524. First-stage planetary gear; 53. Second-stage reduction assembly; 531. Second-stage sun gear; 532. Second-stage planetary carrier; 533. Output ring; 534. Second-stage planetary gear; 6. Receiving slot; 61. Limiting slot; 7. Heat sink; 8. Tension spring; 71. Rotating wheel. Detailed Implementation

[0034] The following is in conjunction with the appendix Figure 1-8 This application will be described in further detail. Example 1

[0035] This application discloses a hub motor for electric bicycles.

[0036] Reference Figure 1 A hub motor for an electric bicycle includes a hub housing 1. A central shaft 2, which provides an installation reference, is inserted inside the hub housing 1. The central shaft 2 is rotatably engaged with the hub housing 1. A freehub base 101 is fixedly connected to one end of the hub housing 1. The freehub base 101 is rotatably connected to the central shaft 2 via a bearing. A chain wheel adapted to a chain can be installed on the freehub base 101 so that the vehicle can be driven by pedaling, which drives the chain wheel and the freehub base 101 to rotate, thereby driving the hub housing 1 to rotate.

[0037] Reference Figure 1 A disc brake end cap 102 is fixedly installed on the side of the hub housing 1 away from the base 101 by bolts, so that the wheel on which it is installed can be braked by the disc brake.

[0038] Reference Figure 1 and Figure 2 The hub housing 1 is equipped with a core cover 3. The central shaft 2 is inserted into the core cover 3 via a flat key. The core cover 3 includes a core cover 31 and a core shell 32 that overlap and fit together. The core cover 3 is equipped with a motor assembly 4. The core cover 3 protects the internal motor assembly 4, reduces the interference of external impurities on the motor assembly 4, and thus extends the overall service life of the motor.

[0039] Reference Figure 1 and Figure 2 The motor assembly 4 includes a stator core 41, which is detachably connected to the end face of the core cover 31 facing the core housing 32 by a plurality of countersunk bolts. The stator core 41 is sleeved on the surface of the central shaft 2, and an insulating frame 42 is sleeved on the outer surface of the stator core 41. A plurality of stator windings (not shown in the figure) are evenly distributed on the insulating frame 42 along the circumference. In this embodiment, the number of stator windings is twelve, and the winding axis of each stator winding is parallel to the axis of the central shaft 2.

[0040] Reference Figure 2 and Figure 3 A rotor disk 43 is rotatably connected to the outer surface of the central shaft 2 via a bearing. The rotor disk 43 is sleeved on the outer surface of the central shaft 2 and is located on the side of the stator core 41 away from the core cover 31. A protrusion is integrally formed on the rotor disk 43, and a permanent magnet 44 consisting of seven pairs of magnetic poles is fixedly installed on the protrusion. Multiple magnets 45 are evenly connected to the surface of the rotor disk 43 along the circumference. In this embodiment, the number of magnets 45 is fourteen. The surface of the rotor disk 43 away from the stator core 41 is connected to the hub housing 1 through a transmission mechanism 5.

[0041] Reference Figure 2 and Figure 3 The end face of the mechanism cover 31 facing the stator core 41 is fixedly mounted with an MR plate 46 by multiple connecting screws, which facilitates the replacement and maintenance of the MR plate 46. A detection element (not shown in the figure) is mounted on the MR plate 46. The sensing end of the detection element faces the surface of the permanent magnet 44. In this embodiment, the detection element is a Hall sensor, and the sensitive direction of the detection element is parallel to the axis of the central axis 2.

[0042] When the stator winding is energized by the power supply device, since the stator winding is wound around the stator core 41 with the central axis 2 as the axis, the magnetic field generated by the magnet 45 cutting the stator winding is parallel to the central axis 2. It cooperates with the permanent magnet 44 to form an axial magnetic field, so that the magnetic field direction of the hub motor is consistent with the sensitive direction of the detection element. This increases the number of magnetic field components that the detection element can detect, improves the basic amplitude of the detection signal, and thus improves the stability of the detection signal and extends the service life of the hub motor.

[0043] Reference Figure 2 and Figure 4The internal housing 32 is fixedly connected to a partition 33. The motor assembly 4 and the transmission mechanism 5 are respectively arranged on both sides of the partition 33. The transmission mechanism 5 includes an internal gear ring 51, a first-stage reduction assembly 52 and a second-stage reduction assembly 53. The internal gear ring 51 is fixedly connected to the inner side wall of the internal housing 32 and is coaxial with the central shaft 2. The power input end of the first-stage reduction assembly 52 is connected to the rotor disk 43, and the power output end is connected to the power input end of the second-stage reduction assembly 53. The power output end of the second-stage reduction assembly 53 is connected to the hub housing 1.

[0044] Reference Figure 2 and Figure 4 Specifically, the first-stage reduction assembly 52 includes a first-stage sun gear base 521, a first-stage sun gear 522, and a first-stage planetary carrier 523, which are sleeved on the outer surface of the central shaft 2. The first-stage sun gear base 521 is fixedly mounted on the rotor disk 43 by three bolts. The inner tooth surface of the first-stage sun gear base 521 meshes with the first-stage sun gear 522. The first-stage planetary carrier 523 is rotatably connected to the outer surface of the central shaft 2 by bearings. Four first-stage planetary gears 524 are rotatably connected on the first-stage planetary carrier 523. The four first-stage planetary gears 524 are all located between the tooth surfaces of the first-stage sun gear 522 and the internal gear ring 51 and mesh with both the first-stage sun gear 522 and the internal gear ring 51.

[0045] Reference Figure 2 and Figure 4 The secondary reduction assembly 53 includes a secondary sun gear 531, a secondary planetary carrier 532, and an output ring 533, all sleeved on the outer surface of the central shaft 2. The secondary sun gear 531 meshes with the internal tooth surface of the primary planetary carrier 523. The secondary planetary carrier 532 is rotatably connected to the outer surface of the central shaft 2 via bearings. Four secondary planetary gears 534 are rotatably connected to the secondary planetary carrier 532. All four secondary planetary gears 534 are located between the tooth surfaces of the secondary sun gear 531 and the internal gear ring 51 and mesh with both the secondary sun gear 531 and the internal gear ring 51. The output ring 533 is fixedly sleeved on the outer surface of the secondary planetary carrier 532. The end face of the output ring 533 away from the secondary planetary carrier 532 is connected to the inner wall of the hub housing 1.

[0046] After the power supply device energizes the stator windings, the electromagnetic induction generated by the stator windings and magnet 45 drives the rotor disk 43 to rotate. The rotation of the rotor disk 43 drives the first-stage sun gear base 521 to rotate, which in turn drives the first-stage sun gear 522 to rotate. This, in turn, drives the four first-stage planetary gears 524 to rotate around their own axes while simultaneously revolving along the tooth surface of the internal gear ring 51. The revolution of the four first-stage planetary gears 524 drives the first-stage planetary carrier 523 to rotate synchronously. The first-stage planetary carrier 523 drives the second-stage sun gear 531 to rotate, and the second-stage sun gear 531 drives... Multiple secondary planetary gears 534 rotate on their own axis while revolving around the tooth surface of the internal gear ring 51, driving the secondary planetary carrier 532 to rotate synchronously. The secondary planetary carrier 532 drives the hub housing 1 to rotate through the output ring 533, thus realizing the power transmission from the rotor disc 43 to the hub housing 1. At the same time, the power is reduced twice by the primary reduction assembly 52 and the secondary reduction assembly 53, so that a large transmission ratio is formed between the rotor disc 43 and the hub housing 1, thereby increasing the output torque of the hub housing 1 and meeting the power requirements of electric bicycles for low speed and high torque.

[0047] The implementation principle of a hub motor for an electric bicycle according to an embodiment of this application is as follows: After the power supply device energizes the stator winding, the electromagnetic induction generated by the stator winding and the magnet 45 drives the rotor disk 43 to rotate. The rotor disk 43 drives the hub housing 1 to rotate through the transmission mechanism 5. During the generation of the magnetic field, since the stator winding is wound on the stator core 41 with the central axis 2 as the axis, the magnetic field generated by the magnet 45 cutting the stator winding is parallel to the central axis 2. It cooperates with the permanent magnet 44 to form an axial magnetic field, so that the magnetic field direction of the hub motor is consistent with the sensitive direction of the detection element. This increases the number of magnetic field components that the detection element can detect, improves the basic amplitude of the detection signal, and thus improves the stability of the detection signal and the service life of the hub motor. Example 2

[0048] Reference Figure 5 and Figure 6 The difference between this embodiment and Embodiment 1 is that a ventilation groove 21 is provided along the axial direction on the side of the central shaft 2 near the disc brake end cover 102, and the ventilation groove 21 extends into the inside of the hub housing 1. Multiple air inlets 311 are evenly provided on the mechanism cover 31 along the circumferential direction. In this embodiment, the number of air inlets 311 is three.

[0049] Reference Figure 6 and Figure 7Multiple air inlets 331 are evenly provided on the outer periphery of the partition plate 33 near the inner wall of the mechanism housing 32. An air duct 321 communicating with the multiple air inlets 331 is provided on the mechanism housing 32. The air duct 321 communicates with the gap between the inner wall of the hub housing 1 and the outer wall of the mechanism housing 32. Multiple air outlets 103 are provided on the side of the hub housing 1 near the disc brake end cover 102. The multiple air outlets 103 are evenly distributed along the outer periphery of the hub housing 1.

[0050] Reference Figure 7 During the operation of the hub motor, external air enters the hub housing 1 through the ventilation slot 21, and then enters the core cover 3 through the air inlet 311. When the air flows inside the core cover 3, it absorbs the heat from the surface of the motor assembly 4 to form hot air. Then, the hot air flows through multiple air inlets 331 and air channels 321 to the gap between the outer wall of the core cover 32 and the inner wall of the hub housing 1, and is finally discharged through multiple air outlets 103. In this way, effective heat dissipation of the motor assembly 4 inside the core cover 3 is achieved, reducing the possibility of performance degradation or component damage caused by high temperature, thereby extending the service life of the motor.

[0051] Reference Figure 7 and Figure 8 To improve the efficiency of convective heat dissipation, multiple receiving grooves 6 are provided on the outer peripheral end face of the rotor disk 43. The length of the receiving grooves 6 is parallel to the radial direction of the rotor disk 43. The multiple receiving grooves 6 are distributed in a spiral shape along the axial direction of the rotor disk 43. Each receiving groove 6 is provided with a heat sink 7 and a tension spring 8. The heat sink 7 is slidably connected inside the receiving groove 6. One end of the tension spring 8 is fixedly connected to the inner side wall of the receiving groove 6 near the axial direction of the central shaft 2, and the other end is fixedly connected to the heat sink 7. The force exerted by the tension spring 8 on the heat sink 7 is opposite to the direction of the centrifugal force on the heat sink 7.

[0052] When the rotor disk 43 rotates, the heat sink 7 tends to slide outward under the action of centrifugal force. When the speed increases, the centrifugal force on the heat sink 7 is greater than the elastic force of the tension spring 8. The heat sink 7 extends out of the receiving groove 6 and is distributed in a spiral pattern on the outer surface of the rotor disk 43. At this time, multiple rotating heat sinks 7 guide the airflow to flow along the spiral trajectory, push the air to form a directional circulation in the axial direction of the rotor disk 43, and accelerate the hot air to flow out through the air inlet 331 and the air groove 321, further improving the convective heat dissipation efficiency. When the speed decreases, the tension spring 8 pulls the heat sink 7 back to reduce wind resistance and reduce energy consumption.

[0053] Reference Figure 7 and Figure 8The receiving groove 6 has a limiting groove 61 on its inner side wall. The two ends of the heat sink 7 are rotatably connected to rotating blocks. The rotating blocks are rolled inside the limiting groove 61. The rotating blocks convert sliding friction into rolling friction, reducing the friction force when the heat sink 7 slides, thereby reducing the heat generated by friction. When the centrifugal force pushes the rotating blocks to the end of the limiting groove 61 away from the central axis 2, a gap is left between the heat sink 7 and the inner side wall of the core housing 32. The maximum extension of the heat sink 7 is controlled by the limiting groove 61 to ensure that there is always a gap between the heat sink 7 and the inner side wall of the core housing 32, thereby avoiding friction heat generation between the heat sink 7 and the core housing 32.

[0054] The implementation principle of Example 2 is as follows: During the operation of the hub motor, external air enters the hub housing 1 through the ventilation slot 21, and then enters the core cover 3 through the air inlet 311. When the air flows inside the core cover 3, it absorbs the heat from the surface of the motor assembly 4 to form hot air. Then, the hot air flows through multiple air inlets 331 and air channels 321 to the gap between the outer wall of the core cover 32 and the inner wall of the hub housing 1, and is finally discharged through multiple air outlets 103. In this way, effective heat dissipation of the motor assembly 4 inside the core cover 3 is achieved, reducing the possibility of performance degradation or component damage caused by high temperature, thereby extending the service life of the motor.

[0055] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A hub motor for an electric bicycle, characterized in that, The assembly includes a hub housing (1), a central shaft (2), and a motor assembly (4). The central shaft (2) passes through the hub housing (1) and is rotatably engaged with it. The motor assembly (4) includes a rotor disk (43) rotatably sleeved on the outer surface of the central shaft (2). The rotor disk (43) is connected to the hub housing (1) via a transmission mechanism (5). A permanent magnet (44) is provided on the outer periphery of the rotor disk (43), and multiple magnets (45) are evenly and equidistantly arranged on its end face. A stator core (41) is fixedly mounted on the central shaft (2). An insulating frame (42) is fitted over the stator core (41). Multiple stator windings are evenly arranged circumferentially on the insulating frame (42). The winding axis of the group is parallel to the axis of the central shaft (2). An MR plate (46) is provided inside the hub housing (1). A detection element is provided on the MR plate (46). The sensing end of the detection element faces the surface of the permanent magnet (44). An internal core cover (3) is provided inside the hub housing (1). The internal core cover (3) covers the outer periphery of the motor assembly (4). The central shaft (2) passes through the internal core cover (3) through a flat key. The internal core cover (3) includes an overlapping internal core cover (31) and an internal core shell (32). The stator core (41) is detachably connected to the internal core cover (31) through multiple countersunk bolts. The MR plate (46) is detachably connected to the internal core cover (31) through connecting screws.

2. A hub motor for an electric bicycle according to claim 1, characterized in that, The transmission mechanism (5) includes an internal gear ring (51), a first-stage reduction assembly (52), and a second-stage reduction assembly (53). The internal gear ring (51) is fixedly disposed inside the core housing (32). The power input end of the first-stage reduction assembly (52) is connected to the rotor disk (43), and the power output end is connected to the power input end of the second-stage reduction assembly (53). The power output end of the second-stage reduction assembly (53) is connected to the hub housing (1).

3. A hub motor for an electric bicycle according to claim 2, characterized in that, The first-stage reduction assembly (52) includes a first-stage sun gear base (521), a first-stage sun gear (522), and a first-stage planetary carrier (523). The first-stage sun gear base (521) is coaxially arranged with the rotor disk (43), and the first-stage sun gear base (521) meshes with the first-stage sun gear (522). The first-stage planetary carrier (523) is provided with a plurality of first-stage planetary gears (524), and the plurality of first-stage planetary gears (524) are all located between the tooth surfaces of the first-stage sun gear (522) and the internal gear ring (51) and mesh with both the first-stage sun gear (522) and the internal gear ring (51). The second-stage reduction assembly (53) includes The system comprises a secondary sun gear (531), a secondary planetary carrier (532), and an output ring (533). The secondary sun gear (531) meshes with the internal tooth surface of the primary planetary carrier (523). The secondary planetary carrier (532) is provided with multiple secondary planetary gears (534). The multiple secondary planetary gears (534) are located between the tooth surfaces of the secondary sun gear (531) and the internal gear ring (51) and mesh with both the secondary sun gear (531) and the internal gear ring (51). The output ring (533) is rotatably sleeved on the central shaft (2). The secondary planetary carrier (532) and the hub housing (1) are both connected to the output ring (533).

4. A hub motor for an electric bicycle according to claim 1, characterized in that, A ventilation slot (21) is provided on the central shaft (2), and the ventilation slot (21) extends into the interior of the hub housing (1). Multiple air inlets (311) are evenly provided on the circumferential side of the mechanism cover (31). A partition (33) is provided inside the mechanism housing (32), and multiple air inlets (331) are evenly provided on the circumferential side of the partition (33). An air duct (321) communicating with the air inlets (331) is provided on the mechanism housing (32). Multiple air outlets (103) are provided on the side of the hub housing (1) near the mechanism cover (31).

5. A hub motor for an electric bicycle according to claim 4, characterized in that, The rotor disk (43) has multiple receiving slots (6) that are parallel to the radial direction of the rotor disk (43). Each receiving slot (6) is slidably connected to a heat sink (7). A tension spring (8) is provided in the receiving slot (6). The force exerted by the tension spring (8) on the heat sink (7) is opposite to the direction of the centrifugal force on the heat sink (7).

6. A hub motor for an electric bicycle according to claim 5, characterized in that, The plurality of the receiving grooves (6) are distributed in a spiral pattern along the axial direction of the rotor disk (43).

7. A hub motor for an electric bicycle according to claim 5, characterized in that, The inner wall of the receiving groove (6) is provided with a limiting groove (61). A rotating block is rotatably connected to the heat sink (7). The rotating block is rolled in the limiting groove (61). When the rotating block abuts against the end of the limiting groove (61) away from the central axis (2), a gap is left between the heat sink (7) and the inner wall of the core housing (32).

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