An ultra-thin in-wheel motor wheel integrating a speed reducer in a low-speed drum brake

Abstract

The present application relates to a kind of ultra-thin wheel hub motor of speed reducer integrated in low-speed drum brake, including cooling water channel, motor, drum brake, planetary gear reducer, wheel hub, wheel hub bearing and wheel axle in the same axial position in turn from outside to inside in radial direction, wherein, wheel hub is connected with wheel rim, the both ends of cooling water channel are respectively connected with electric motor outer shell and electric motor inner shell, the transmission path of driving force in electric motor is: motor to planetary gear reducer to wheel hub to wheel rim.Compared with prior art, the present application can maximize the axial space of electric motor assembly to be compressed, facilitate the layout of speed reduction wheel hub motor assembly in vehicle wheel end, with the advantages of space height integration, axial space limit compression.

Description

Technical Field

[0001] This invention relates to the field of hub electric drive assembly technology, and in particular to an ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake. Background Technology

[0002] Hub motor electric drive (HEV) refers to a drive system that integrates an electric motor inside the wheel. Compared to traditional engine and transmission drive systems, HEV integrates both the power source and transmission system within the wheel, offering advantages such as high space utilization, low energy loss, and high efficiency. Furthermore, the distributed drive technology implemented based on HEV further decouples the drive wheel power, facilitating more advanced control and significantly improving vehicle dynamic performance. This represents a crucial direction in the current development of new energy vehicle technology.

[0003] Currently, hub electric drive technology mainly falls into two categories: direct-drive hub electric wheels and geared hub electric wheels. Direct-drive hub electric wheels directly drive the wheel using a motor integrated inside the wheel. This type primarily includes two configurations: external rotor and internal rotor. Because it eliminates the reducer structure, direct-drive electric wheels are structurally simpler and more efficient. However, due to the removal of the reducer's torque amplification, the motor needs a larger torque output, thus placing higher demands on motor performance. In contrast, geared hub electric wheels integrate the motor and reduction mechanism inside the wheel. The driving force is reduced and amplified by the reducer before being output to the wheel, resulting in a larger output torque and better low-speed performance. However, this design places relatively lower demands on the motor's torque density. For example, Chinese patent CN206908460U proposes a reduction hub motor. This reduction hub motor includes a motor mounting base, a stator mechanism connected to the mounting base, a rotor mechanism sleeved on the outside of the stator mechanism, a motor rear cover connected to the rotor mechanism away from the motor mounting base, a rotating shaft inserted inside the stator mechanism and rotatably connected to the stator mechanism connected to the rear cover, one end of the rotating shaft near the mounting base extending out of the stator mechanism and connected to a reduction gear mechanism, a rotating outer shell covering the outside of the rotor mechanism connected to the reduction gear mechanism, and the wheel hub sleeved on the rotating outer shell of the reduction hub motor. Because this method integrates the reduction mechanism inside the wheel, its overall structure, manufacturing, and assembly processes are relatively complex, and its overall size, especially the axial dimension, is large. This drawback makes it difficult to arrange the reduction hub electric wheel assembly at the wheel rim, easily causing interference with suspension and other components. This not only makes it difficult to place the reduction hub electric wheel assembly at the vehicle wheel end but also hinders large-scale production.

[0004] With the development of the new energy vehicle industry, the application scope of deceleration hub electric wheel technology is constantly expanding. However, there are still technical challenges in solving the problem of deep integration of hub motors, improving performance, power density and torque density, and realizing the application of hub electric systems in vehicles. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide an ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake, which can maximize the compression of the axial space of the electric wheel assembly and facilitate the layout of the reducer hub electric wheel assembly at the wheel end of the vehicle.

[0006] The objective of this invention can be achieved through the following technical solution: an ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake, comprising a cooling water channel, a motor, a drum brake, a planetary gear reducer, a hub, a hub bearing, and a wheel axle arranged radially from the outside to the inside and in the same axial position. The hub is connected to the rim. The two ends of the cooling water channel are respectively connected to the outer shell of the electric wheel and the inner shell of the electric wheel. The transmission path of the driving force in the electric wheel is: motor to planetary gear reducer to hub to rim.

[0007] Furthermore, the inner housing of the electric wheel is rigidly connected to the axle via the wheel axle, and the inner housing of the electric wheel, the outer housing of the electric wheel, and the cooling water channel are connected by bolts to form an integral housing structure.

[0008] Furthermore, the overall shell structure has a stepped shape, and the dimensions of the overall shell structure decrease along the axial direction from the center to the edge.

[0009] Furthermore, four radially arranged spaces are separated between the outer casing of the electric wheel and the inner casing of the electric wheel, which are used to arrange the motor, drum brake, planetary gear reducer, wheel hub and wheel hub bearing respectively from the outside to the inside in the radial direction.

[0010] Furthermore, the drum brake includes brake shoes, brake wheel cylinder, brake shoe shaft, return spring, and brake drum. The brake shoes, brake wheel cylinder, and brake shoe shaft are respectively fixedly connected to the outer shell of the electric wheel. The return spring is pulled between the two brake shoes for returning the brake shoes to their original position when not braking. The brake drum is torsionally connected to the wheel hub and rotates with it, for transferring braking torque to the wheel hub during braking.

[0011] Furthermore, the cooling water channel, the electric wheel housing, and the brake wheel cylinder are equipped with a brake oil circuit structure. The brake oil circuit structure is divided into three sections. The first section is located at the bottom thickened position of the cooling water channel, and its right end is equipped with an oil circuit connector that connects to the vehicle's brake lines. The second section is machined along the shape of the electric wheel housing, and its upper end is connected to the first section of the brake oil circuit and is equipped with a sealing ring. The third section is connected to the piston of the brake wheel cylinder, and its right end is connected to the second section of the brake oil circuit and is equipped with a sealing ring.

[0012] Furthermore, the motor includes a stator and a rotor, the stator being nested inside a cooling water channel, and the rotor being nested on a motor rotor support and mounted on the inner housing of the electric wheel via a deep groove ball bearing.

[0013] Furthermore, the planetary gear reducer includes a planetary ring gear, planetary gears, a planetary carrier, and a sun gear. The planetary ring gear is fixed inside the electric motor housing. The sun gear is sleeved on the motor rotor support and is torsionally connected to the motor rotor support. The planetary gears, planetary carrier, sun gear, and planetary ring gear are axially floatingly connected.

[0014] Furthermore, a rotary transformer is installed between the sun gear and the inner housing of the electric wheel to monitor the motor speed.

[0015] Furthermore, the hub bearing is a double-row opposed angular contact roller bearing, the inner ring of the hub bearing is fitted onto the axle and is axially positioned by a locating nut at the end of the axle; the rollers of the hub bearing maintain their relative positions with a cage and are installed between the inner ring and the axle.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] In this invention, the cooling water channel, motor, drum brake, planetary gear reducer, wheel hub, wheel hub bearing, and wheel axle are arranged radially from the outside to the inside and are located in the same axial position, which has the advantage of extremely high integration. The various structures of the electric wheel assembly are highly integrated radially, and the axial space is greatly compressed, which is in line with the characteristics of electric vehicle wheel rims having large radial dimensions and small axial arrangement space, and facilitates the layout of the reduction wheel hub electric wheel assembly at the wheel end.

[0018] In this invention, the inner shell of the electric wheel, the outer shell of the electric wheel, and the cooling water channel are connected by bolts to form an integral shell structure. That is, the cooling water channel itself is an integral part of the electric wheel shell, which is highly integrated in structure and reduces the overall space volume of the electric wheel. The integral shell structure has a stepped shape, and the dimensions of the integral shell structure decrease from the center to the edge along the axial direction. Four radially arranged spaces are separated between the outer shell of the electric wheel and the inner shell of the electric wheel to arrange the motor, drum brake, planetary gear reducer, wheel hub and wheel hub bearing respectively from the outside to the inside in the radial direction. This ingeniously realizes the nesting of multiple structures, so that the overall structure of the electric wheel assembly is highly integrated and the axial space is compressed to the maximum extent.

[0019] In this invention, the drum brake is located radially between the motor and the planetary gear reducer, with a compact axial space and a well-designed radial dimension. Furthermore, by placing the hub, hub bearing, and axle at the innermost part of the radial space, the radial dimension of the hub bearing is greatly reduced, the weight of the hub bearing is decreased, and its reliability is improved. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of the electric wheel assembly of the present invention;

[0021] Figure 2 This is a schematic diagram of the explosion of the force transmission component in this invention;

[0022] Figure 3 This is a schematic diagram of the internal structure of the drum brake in this invention;

[0023] Figure 4 This is a schematic diagram of the planetary gear reducer in this invention;

[0024] Explanation of markings in the diagram: 1. Cooling water channel; 2. Electric wheel housing; 3. Brake drum; 4. Brake wheel cylinder; 5. Oil drain valve; 6. Brake drum fixing bolt; 7. Wheel hub; 8. First oil seal; 9. Breather valve; 10. Wheel hub bolt; 11. Wheel hub bearing; 12. Inner ring; 13. Locating nut; 14. End cap; 15. Reducer outer planetary carrier; 16. Reducer planetary carrier pin; 17. Brake shoe; 18. Return spring; 19. Oil drain bolt; 20. Water passage connection. 21. Head, oil line connector, 22. Electric wheel inner housing, 23. Motor rotor support, 24. Planetary gear ring, 25. Planetary gear, 26. Reducer needle roller bearing, 27. Reducer inner planetary carrier, 28. Sun gear, 29. Sun gear needle roller bearing, 30. Wheel axle, 31. Second oil seal, 32. Rotary transformer rotor, 33. Rotary transformer stator, 34. Deep groove ball bearing, 35. Third oil seal, 36. Brake shoe shaft, 37. Rotor, 38. Stator. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] Example

[0027] like Figure 1 and Figure 2 As shown, an ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake has the following main structures: an electric wheel housing (including an outer electric wheel housing 2, an inner electric wheel housing 22, and a cooling water channel 1), a motor (including a rotor 37 and a stator 38) and its water-cooling system, a drum brake, a planetary gear reducer and its splash lubrication cooling system, a hub bearing 11, a wheel axle 3, and a hub 7. The cooling water channel (1), motor, drum brake, planetary gear reducer, hub (7), hub bearing (11), and wheel axle (30) are all located in the same axial position and arranged radially from the outside to the inside. Therefore, the axial space of the electric wheel assembly is significantly compressed, and the various structures are highly integrated radially, which conforms to the characteristics of electric vehicle rims having large radial dimensions and small axial arrangement space, facilitating the arrangement of the electric wheel assembly in the vehicle.

[0028] The planetary gear reducer is located radially inside the drum brake, resulting in a smaller overall axial dimension and a more compact overall structure for the electric wheel. The driving force transmission path in the electric wheel is as follows: motor stator 38 - motor rotor 37 - motor rotor support 23 - reducer sun gear 28 - reducer planetary gears 25 - reducer outer planetary carrier 15 - hub 7 - hub bolts 10 - rim and tire.

[0029] The overall shape of the electric wheel housing is stepped, with the axial dimension decreasing from the center to the edge. The inner housing 22 of the electric wheel is rigidly connected to the axle 30, serving to support the entire reduction electric wheel. The inner housing 22 and the outer housing 2 of the electric wheel are bolted to the cooling water channel 1, forming the overall housing structure of the reduction electric wheel. Four radially arranged main design spaces are separated between the outer housing 2 and the inner housing 22 of the electric wheel, used to arrange the motor, drum brake, planetary gear reducer, wheel hub 7, and wheel hub bearing 11 radially from the outside to the inside. Other structures, such as the rotary transformer (including the rotary transformer rotor 32 and rotary transformer stator 33), the sun gear needle roller bearing 29, the rotor support deep groove ball bearing 34, and oil seals (including the first oil seal 8, the second oil seal 31, and the third oil seal 35), are arranged near the center, overlapping with the main structures, and only the motor is arranged at the edge, forming an axial dimension decreasing from the center to the edge, which is convenient for actual vehicle installation.

[0030] In this embodiment, the motor type is an internal rotor brushless permanent magnet synchronous motor (PMSM). The cooling water channel 1 is part of the outer shell structure of the geared wheel hub electric wheel. Coolant flows inside to cool the motor. The motor stator 38 is nested inside the cooling water channel 1 by heat fitting. (The stator 38 and the winding part should be rigidly connected to the inside of the cooling water channel 1 in the circumferential direction. The winding length of the stator 38 should be slightly smaller than the inner radial arrangement space of the shell to ensure the installability of the stator 38 and the electromagnetic stability of the winding.) The motor rotor 37 is fixed on the motor rotor bracket 23. It is mounted on the inner shell 22 of the electric wheel through a deep groove ball bearing 34 to achieve support and free rotation. The rotor 37 should be nested on the motor rotor bracket 23 and maintain a torsional connection with the reducer sun gear 28. The motor rotor bracket 23 is sleeved on the reducer sun gear 28 to transmit power. The rotary transformer (including the rotary transformer rotor 32 and the rotary transformer stator 33) is installed between the reducer sun gear 28 and the inner shell 22 of the electric wheel to monitor the motor speed.

[0031] like Figure 3 As shown, in this embodiment, the drum brake is specifically a leading-following shoe type, located radially between the motor and the planetary gear reducer, achieving integration of the low-speed drum brake with the motor housing. This drum brake includes brake shoes 17, brake wheel cylinders 4, brake shoe shafts 36, return springs 18, and a brake drum 3. Brake shoes 17, brake wheel cylinders 4, and brake shoe shafts 36 are fixedly connected to the electric wheel housing 2 (both ends of the brake wheel cylinders 4 contact the ends of brake shoes 17, and the other end of brake shoes 17 is mounted on the electric wheel housing 2 via the brake shoe shafts 36). The return spring 18 pulls between the two brake shoes (the return spring 18 ensures contact between the two brake shoes 17 and the brake wheel cylinder 4), used for brake shoe return in non-braking states; the brake drum is torsionally connected to the hub and rotates with it (the brake drum 3 is connected to the hub 7 via brake drum fixing bolts 6, maintaining a gap between it and the brake shoes 17), transferring braking torque to the hub during braking.

[0032] The brake fluid circuit of the above drum brake is divided into three sections, located in the cooling water channel 1, inside the electric wheel housing 2, and in the brake wheel cylinder 4, respectively: The first section is located in the electric motor cooling water channel 1, where a brake fluid circuit is machined at the thickened bottom of the electric motor cooling water channel 1, and a fluid circuit connector 21 is installed at its right end to connect to the vehicle's brake lines; the second section is located in the electric wheel housing 2, where a brake fluid circuit following the shape of the electric wheel housing 2 is machined using a drilling and welding filling method, and its upper end is connected to the first section of the brake fluid circuit and is fitted with a sealing ring; the third section is located in the brake wheel cylinder 4, connected to the piston of the brake wheel cylinder 4, and its right end is connected to the second section of the brake fluid circuit and is fitted with a sealing ring. In addition, a drain valve 5 is installed at an upward angle in the brake wheel cylinder 4 to discharge air from the brake fluid circuit.

[0033] like Figure 4 As shown, the planetary gear reducer includes the following basic structures: planetary ring gear 24, planetary gears 25, planetary carrier (including the outer planetary carrier 15 and the inner planetary carrier 27), and sun gear 28. The planetary ring gear 24 is fixed inside the electric wheel housing 2 and is connected to the electric wheel housing 2 via splines. The sun gear 28 is torsionally connected to the motor rotor support 23 and is supported by a deep groove ball bearing 34 and a sun gear needle roller bearing 29. The reducer sun gear 28 is sleeved on the motor rotor support 23, transmitting drive torque. The planetary gears 25, planetary carrier 27, sun gear 28, and planetary ring gear 24 are axially floatingly connected. The planetary gears 25 are connected to the planetary carrier via the reducer needle roller bearing 26. The planetary carrier is mounted on the hub 7 via splines, transmitting drive torque.

[0034] In addition, the planetary gear reducer adopts splash lubrication and cooling. The splash lubrication and cooling system of the planetary gear reducer includes an oil filling port located at the hub 7, an oil drain channel located at the bottom of the electric wheel housing 2, and three oil seals (including the first oil seal 8, the second oil seal 31, and the third oil seal 35), located between the sun gear 28 and the hub 7, between the motor rotor support 23 and the electric wheel housing 2, and between the electric wheel housing 2 and the hub 7, respectively. This system enables the filling and draining of lubricating oil, provides dynamic sealing, and ensures the normal operation of the splash lubrication and cooling system. Specifically, lubricating oil is added through the opening at the installation position of the breather valve 9; the three oil seals provide dynamic sealing of the lubricating oil in the internal cavity of the reducer; and waste lubricating oil is drained through the oil drain channel at the bottom of the electric wheel housing 2 and the drain bolt 19. Due to the special position of the reducer, the breather valve 9 is also needed to connect the internal structure with the external atmosphere to prevent excessive internal pressure and ensure that the lubricating oil does not leak out.

[0035] In this embodiment, the hub bearing 11 is a double-row, opposing angular contact roller bearing. The inner ring 12 of the bearing is sleeved on the axle 30 and axially positioned by the locating nut 13 at the end of the axle 30. The rollers are maintained in relative position by a cage and are installed between the inner ring 12 of the bearing and the axle 30. The hub 7 has grooves inside, which directly serve as bearing raceways. Grease is stored inside the hub 7 to lubricate the hub bearing 11. The axle 30 is fixed on the axle and supports the entire electric wheel of the reduction hub. The hub bearing 11 is installed on the axle 30. The hub 7 is mounted on the axle 30 through the hub bearing 11 and transmits driving torque through the sleeve between it and the outer planetary carrier 15 of the reducer. It is fixedly connected to the brake drum 3 to transmit braking torque. Hub bolts 10 are installed on the hub 7 to fix the rim and tire.

[0036] The drive / braking torque transmission path of the aforementioned ultra-thin hub electric wheel includes:

[0037] (1) In the process of realizing the motor driving and regenerative braking, the torque starts from the motor rotor, passes through the motor rotor support, and is transmitted to the sun gear through the interference fit between the motor rotor support and the sun gear. Then, the torque is reduced and increased through the planetary gear reducer, and the torque is transmitted to the wheel hub through the outer planetary carrier of the reducer. Finally, the torque is transmitted to the rim and tire through the wheel hub bolts installed on the wheel hub.

[0038] (2) During mechanical braking by a low-speed drum brake device, frictional torque is generated by the contact and friction between the brake shoes mounted on the electric wheel housing and the brake drum connected to the wheel hub. The braking torque is transmitted to the wheel rim via the hub bolts on the wheel hub. In non-braking conditions, the brake drum and the brake shoes pulled by the return spring do not contact each other radially. During braking, the brake shoes are pressed against the inner wall of the brake drum by the hydraulic pressure of the brake wheel cylinder, and friction generates braking torque.

[0039] In summary, this solution, through the special configuration of the inner and outer shells of the electric wheel, separates the outer and inner shells of the electric wheel into four radially arranged main design spaces. The main components of the reduction hub electric wheel—motor stator and rotor, drum brake, planetary gear reducer, hub, hub bearing, and axle—are arranged sequentially from the outside to the inside in the radial space, and are basically located in the same position in the axial direction. This ingeniously achieves multiple structural nesting, making the overall structure of the electric wheel assembly highly integrated, maximizing the compression of axial space, and facilitating the layout of the reduction hub electric wheel assembly at the vehicle wheel end.

[0040] In this design, the motor is a water-cooled motor, and the motor cooling water channel itself is an integral part of the electric wheel housing, achieving a high degree of structural integration and reducing the overall volume of the electric wheel. The motor stator is housed within the motor cooling water channel, and coolant is used to cool the stator, achieving good cooling performance while avoiding damage to the stator and motor caused by oil cooling. The planetary gear reducer uses splash lubrication for both lubrication and cooling. While ensuring the basic performance requirements of the electric wheel, such as lubrication and cooling, it eliminates the need for an oil pump system, significantly reducing system weight and energy consumption, and improving system integration. Overall, the cooling method adopted in this design meets the basic performance requirements of the reduction hub electric wheel, greatly improves the integration of the electric wheel assembly, reduces costs, and enhances stability and efficiency.

[0041] In this design, the low-speed drum brake is installed radially between the motor and the planetary gear reducer, resulting in a compact axial space and a well-designed radial dimension. The larger radial dimension of the brake drum allows for greater braking torque under the same braking pressure. The brake drum is connected to the wheel hub, and its rotational speed is the same as the wheel end speed, leading to less wear during braking. Compared to braking at the motor rotor end, this significantly extends the lifespan of the drum brake.

[0042] In this design, the hub, hub bearing, and axle are located at the innermost part in the radial space, which greatly reduces the radial dimension of the hub bearing, reduces its weight, and improves its reliability. The hub bearing adopts two opposing angular contact roller bearings, which improves the axial load capacity of the hub bearing.

[0043] Applying this solution to practical applications enables a highly integrated, axially compressed, hub-and-spoke electric wheel configuration. This results in a minimal axial dimension of the hub-and-spoke electric wheel assembly, facilitating its placement at the wheel end. The motor utilizes water cooling, while the reducer employs splash oil cooling and lubrication to ensure optimal system cooling and lubrication performance. The drum brake directly brakes the low-speed end, resolving the short lifespan issue of high-speed drum brakes. The overall structure caters to the characteristics of electric vehicle rims—large radial dimensions and limited axial space—while also offering advantages such as low cost and ease of maintenance.

Claims

1. An ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake, characterized in that, The device includes a cooling water channel (1) arranged radially from the outside to the inside and located in the same axial position, a motor, a drum brake, a planetary gear reducer, a wheel hub (7), a wheel hub bearing (11), and a wheel axle (30). The wheel hub (7) is connected to the wheel rim. The two ends of the cooling water channel (1) are respectively connected to the outer shell (2) of the electric wheel and the inner shell (22) of the electric wheel. The transmission path of the driving force in the electric wheel is: motor to planetary gear reducer to wheel hub (7) to wheel rim. The drum brake includes a brake shoe (17), a brake wheel cylinder (4), a brake shoe (17) shaft, a return spring (18), and a brake drum (3). The brake shoe (17), brake wheel cylinder (4), and brake shoe (17) shaft are fixedly connected to the electric wheel housing (2). The return spring (18) is pulled between the two brake shoes (17) and is used to return the brake shoes (17) to their original position when not braking. The brake drum (3) is torsionally connected to the wheel hub (7) and rotates with it, and is used to transfer the braking torque to the wheel hub (7) when braking. The cooling water channel (1), the electric wheel housing (2), and the brake wheel cylinder (4) are equipped with a brake oil circuit structure. The brake oil circuit structure is divided into three sections. The first section is located at the bottom thickened position of the cooling water channel (1), and an oil circuit connector is installed at its right end to connect with the vehicle brake line. The second section is machined along the shape of the electric wheel housing (2), and its upper end is connected to the first section of the brake oil circuit and is equipped with a sealing ring. The third section is connected to the piston of the brake wheel cylinder (4), and its right end is connected to the second section of the brake oil circuit and is equipped with a sealing ring.

2. The ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake according to claim 1, characterized in that, The inner housing (22) of the electric wheel is rigidly connected to the axle (30). The inner housing (22), the outer housing (2) of the electric wheel, and the cooling water channel (1) are connected by bolts to form an integral housing structure.

3. The ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake according to claim 2, characterized in that, The overall shell structure has a stepped shape, and the dimensions of the overall shell structure decrease along the axial direction from the center to the edge.

4. The ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake according to claim 3, characterized in that, The electric wheel outer shell (2) and the electric wheel inner shell (22) are separated into four radially arranged spaces for arranging the motor, drum brake, planetary gear reducer, wheel hub (7) and wheel hub bearing (11) respectively from the outside to the inside in the radial direction.

5. The ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake according to claim 2, characterized in that, The motor includes a stator (38) and a rotor (37), the stator (38) being nested inside a cooling water channel (1), and the rotor (37) being nested on a motor rotor (37) bracket (23) and mounted on an electric wheel inner housing (22) via a deep groove ball bearing (34).

6. The ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake according to claim 5, characterized in that, The planetary gear reducer includes a planetary ring gear (24), planetary gears (25), a planetary carrier, and a sun gear (28). The planetary ring gear (24) is fixed inside the electric wheel housing (2). The sun gear (28) is sleeved on the motor rotor (37) support (23) and is torsionally connected to the motor rotor (37) support (23). The planetary gears (25), the planetary carrier, the sun gear (28), and the planetary ring gear (24) are axially floatingly connected.

7. The ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake according to claim 6, characterized in that, A rotary transformer is installed between the sun gear (28) and the inner housing (22) of the electric wheel to monitor the motor speed.

8. The ultra-thin hub electric wheel with a reducer integrated into a low-speed drum brake according to claim 1, characterized in that, The hub bearing (11) is a double-row opposed angular contact roller bearing. The inner ring of the hub bearing (11) is fitted onto the axle (30) and is axially positioned by the positioning nut at the end of the axle (30). The rollers of the hub bearing (11) are maintained in relative position by a cage and are installed between the inner ring and the axle (30).

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