A hub direct-drive electric wheel structure with integrated disc brake

Abstract

This invention relates to a hub-driven electric wheel structure with an integrated disc brake, comprising an electric wheel housing. Within the housing are an outer rotor of a motor, a motor stator, a ventilated brake disc, and an aluminum alloy inner brake caliper. A heat insulation device is provided between the outer circumference of the ventilated brake disc and the electric wheel housing, and a heat insulation baffle is provided between the ventilated brake disc and the motor dynamic seal. The aluminum alloy inner brake caliper is disposed within the inner circumference of the ventilated brake disc, forming a brake assembly. Compared with existing technologies, this invention effectively solves the problem of brake thermal management through structural integration and material innovation, improves motor reliability and system power density, and enables a lightweight, high-thermal-isolation hub-driven electric wheel.

Description

Technical Field

[0001] This invention relates to the field of hub electric drive assembly technology, and in particular to a hub direct drive electric wheel structure with integrated disc brake. Background Technology

[0002] Hub motor electric drive (HEV) technology refers to a drive system that integrates an electric motor inside the wheel. Compared to traditional engine and transmission drive systems, HEV systems offer numerous advantages, including a simplified power transmission path, efficient energy utilization, better suspension design and vehicle balance, lower noise and vibration, and improved vehicle handling and reliability.

[0003] In-wheel direct-drive electric wheels and in-wheel reduction electric wheels are currently the two main development directions of in-wheel electric drive technology. In-wheel direct-drive electric wheels refer to a drive method that integrates the electric motor inside the wheel, directly driving it. In the new energy vehicle industry, compared to in-wheel reduction electric wheels, in-wheel direct-drive electric wheels offer higher efficiency and a simpler structure, providing faster acceleration and a better driving experience. However, the disadvantages of this technology include the need for higher motor power and a more complex control system, as well as higher manufacturing and maintenance costs.

[0004] Currently, the application of hub-driven electric wheels is mainly concentrated in the fields of high-performance electric vehicles and racing cars. During braking, the high temperature generated by the brake disc in existing hub-driven motors (reaching over 600℃) can easily affect the permanent magnets and windings of the motor through heat conduction, leading to demagnetization, insulation aging, and reduced motor life and efficiency. The separate design of the brake and motor results in low hub space utilization and heavy weight, which is not conducive to the overall vehicle lightweighting. Traditional cast iron brake discs have low heat capacity and are prone to heat fade at high temperatures; brake calipers are mostly made of cast iron and are heavy.

[0005] To address these issues, existing technologies employ heat insulation, carbon-ceramic brake discs, and external brake calipers. However, heat insulation methods mostly involve adding heat sinks or air ducts, which fail to block heat conduction paths and increase size. While carbon-ceramic brake discs are heat-resistant, they are not integrated with the motor rotor, hindering structural lightweighting. External brake caliper placement occupies rim space, limiting motor size and power density. All of these factors hinder the application of hub-driven electric wheels in electric vehicles, electric motorcycles, and other scenarios requiring efficient braking and drive integration. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a hub direct-drive electric wheel structure with an integrated disc brake. Through structural integration and material innovation, it solves the problem of brake thermal management, improves motor reliability and system power density, and realizes a lightweight hub direct-drive electric wheel with high thermal isolation.

[0007] The objective of this invention can be achieved through the following technical solution: a hub direct-drive electric wheel structure with an integrated disc brake, comprising an electric wheel housing, wherein an outer rotor of a motor, a motor stator, a ventilated brake disc, and an aluminum alloy inner brake caliper are installed inside the electric wheel housing, a heat insulation device is provided between the outer circumference of the ventilated brake disc and the electric wheel housing, a heat insulation baffle is provided between the ventilated brake disc and the motor dynamic seal, and the aluminum alloy inner brake caliper is disposed in the inner circumference space of the ventilated brake disc, constituting a brake assembly.

[0008] Furthermore, the heat insulation device includes a boss structure that is evenly distributed along the outer circumference of the ventilated brake disc, and a heat insulation gasket is installed between the boss structure and the electric wheel housing.

[0009] Furthermore, the thermal conductivity of the heat insulation pad is lower than that of the ventilated brake disc, and the specific heat capacity of the heat insulation pad is greater than that of the ventilated brake disc.

[0010] Furthermore, the ventilated brake disc is made of carbon ceramic material, and the heat insulation pad is made of ceramic fiber material.

[0011] Furthermore, the ventilated brake disc has a thin-walled annular structure, and multiple ventilation holes are provided on the ventilated brake disc. Multiple lifting lugs are provided on the outer wall of the ventilated brake disc, and the lifting lugs are connected to the electric wheel housing by flange bolts.

[0012] Furthermore, the aluminum alloy internal brake caliper includes a brake block and a caliper body. The caliper body includes a caliper cylinder and a caliper back that are internally mounted on both sides of the ventilated brake disc. The caliper cylinder and the caliper back are connected by a caliper bracket. Furthermore, the heat insulation baffle is a ring-shaped or partially extended plate-like structure, arranged on the side of the dynamic sealing element closest to the external environment, forming a physical protective barrier.

[0013] Furthermore, the heat insulation baffle is composed of stacked stainless steel foils, with aerogel filling the spaces between the stainless steel foils.

[0014] Furthermore, the support surface of the motor stator is coated with a heat-insulating coating on the side near the ventilated brake disc to block heat transfer from the ventilated brake disc and reflect heat radiation.

[0015] Furthermore, the substrate of the heat insulation coating is selected from magnesium-aluminum alloy, and an Al2O3-SiO2 coating is applied by plasma spraying.

[0016] Compared with the prior art, the present invention has the following advantages: This invention incorporates a heat insulation device between the outer circumference of the ventilated brake disc and the electric wheel housing, a heat insulation baffle between the ventilated brake disc and the motor dynamic seal, and an aluminum alloy inner brake caliper positioned within the inner circumference of the ventilated brake disc, thus constructing an integrated brake assembly. This effectively isolates the brake assembly from heat transfer and heat radiation to the motor, reduces the axial arrangement space of the electric wheel, and achieves a lightweight design.

[0017] The heat insulation device designed in this invention includes a boss structure, which is evenly distributed along the outer circumference of the ventilated brake disc. A heat insulation gasket is installed between the boss structure and the electric wheel housing. The boss structure ensures the positioning and assembly error of the brake disc. While ensuring the strength of the assembly, the boss structure reduces the contact area between the outer circumference of the brake disc and the hub motor housing, thereby reducing heat transfer. In addition, the heat insulation gasket can prevent the brake disc from transferring heat to the outer rotor of the motor.

[0018] In this invention, the thermal conductivity of the heat insulation pad is lower than that of the ventilated brake disc, and the specific heat capacity of the heat insulation pad is greater than that of the ventilated brake disc, making it difficult for the heat from the ventilated brake disc to be transferred to the heat insulation pad.

[0019] In this invention, the ventilated brake disc is a thin-walled annular structure with multiple ventilation holes. These ventilation holes create forced convection when the brake disc rotates, improving heat dissipation efficiency and guiding brake dust away, reducing brake pad wear rate and reducing weight. In addition, multiple lifting lugs are provided on the outer wall of the ventilated brake disc. These lugs are connected to the electric wheel housing via flange bolts, ensuring uniform stress on the brake disc and avoiding the risk of cracking caused by localized stress concentration.

[0020] This invention uses an aluminum alloy to make a dual-cylinder internal brake caliper, and the ventilated brake disc and caliper are internally connected, which is conducive to the lightweighting of the wheel hub electric wheel assembly. It also has good thermal conductivity, so the heat generated during braking can be dissipated more quickly, reducing heat fade and improving braking stability and durability.

[0021] The present invention designs the heat insulation baffle as a ring or partially extended plate structure, and arranges the heat insulation baffle on the side of the dynamic sealing element that is close to the external environment to form a physical protective barrier. The heat insulation baffle is composed of stacked stainless steel foils, with aerogel filling the spaces between the stainless steel foils, which can effectively reflect the heat radiation from the brake assembly.

[0022] The present invention applies a heat-insulating coating to the side of the motor stator support surface near the ventilated brake disc, which further serves to block heat transfer from the brake assembly and reflect heat radiation. Attached Figure Description

[0023] Figure 1This is a cross-sectional view of the hub direct-drive electric wheel assembly structure of the present invention; Figure 2 This is a schematic diagram of the brake assembly structure in this invention; Figure 3 This is an exploded view of the aluminum alloy internal brake caliper structure in this invention; Figure 4 This is a side view of the structure of the ventilated brake disc in this invention; Figure 5 This is a plan view of the ventilated brake disc in this invention; Figure 6 This is a schematic diagram of the heat insulation device structure at the connection between the ventilated brake disc and the electric wheel housing in this invention; Figure 7 This is a side view of the structure of the motor dynamic seal in this invention; Figure 8 This is a structural end face view of the motor dynamic seal in this invention; The markings in the diagram are as follows: 1. Electric wheel housing; 2. Motor outer rotor; 3. Motor stator; 4. Support surface; 5. Support inner sleeve; 6. Flange bolt; 7. Resolver stator; 8. Resolver rotor; 9. Flange bolt; 10. Flange; 11. Flange bolt; 12. Flange bolt; 13. Dynamic seal; 14. Flange bolt; 15. Ventilated brake disc; 16. Hex head bolt; 17. Junction box; 18. AC wiring harness; 19. Socket head cap screw; 20. Low-voltage junction box; 21. Low-voltage wiring harness; 22. Caliper bracket; 23. Caliper cylinder; 24. Brake block; 25. Caliper back; 26. Sealing bolt; 27. Guide pin dust cover; 28. Piston; 29. ​​Cover plate; 30. Rectangular ring; 31. Guide pin; 32. Bolt; 33. Heat insulation gasket; 34. Boss structure. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0025] Example like Figure 1 As shown, a hub-driven electric wheel structure with an integrated disc brake mainly includes an electric wheel housing 1 arranged axially, an outer rotor 2 of the motor, a stator 3 of the motor and its water-cooling system, a ventilated brake disc 15, and an aluminum alloy inner brake caliper. Among them, as... Figure 2 As shown, the aluminum alloy inner brake caliper is installed in the inner circumferential space of the ventilated brake disc 15, thus forming the brake assembly.

[0026] This solution mainly achieves lightweight and high thermal insulation of hub-driven electric wheels through structural integration innovation (built-in brake caliper, integrated brake disc-rotor), material innovation (carbon ceramic disc + aluminum alloy brake caliper) and thermal blocking design (double-stage heat insulation).

[0027] Specifically, the aluminum alloy internal brake caliper is made of aluminum alloy and is internally connected to the ventilated brake disc. This design achieves weight reduction, as the density of aluminum alloy typically ranges from 2.63 to 2.85 g / cm³. 3 (The density range of traditionally selected cast iron materials is typically 6.6 to 7.7 g / cm³) 3 The use of aluminum alloy helps reduce weight; secondly, it offers better thermal management, as aluminum alloy conducts heat quickly, reducing heat loss; and thirdly, it optimizes space, with the internal clamping structure suitable for the compact space of the wheel hub motor. Figure 3 As shown, the aluminum alloy internal brake caliper adopts a modular design (for easy assembly and maintenance), including brake pads 24, caliper body (composed of caliper bracket 22, caliper cylinder 23 and caliper back 25), guide pins 31, springs or circlip-like parts (including cover plate 29, rectangular ring 30, etc.), and pistons 28. The guide pins 31 are bolted to achieve a reliable mechanical connection, ensuring the stability of the brake caliper during operation and being able to withstand the reaction force during braking. The design of the guide pins 31 also ensures the correct movement of the brake caliper body during braking, so that the brake pads 24 and the ventilated brake disc 15 can fit accurately, thereby improving the responsiveness and accuracy of braking. Through uniform braking force distribution and accurate guidance, it is beneficial to improve braking effect and stability.

[0028] like Figure 4 and Figure 5 As shown, the ventilated brake disc 15 is made of C / SiC ceramic matrix composite material, with ventilation ribs in the middle, providing excellent air-cooling heat dissipation. The density of the carbon ceramic material is less than 2 g / cm³. 3 The design employs a carbon-ceramic ventilated brake disc paired with an aluminum alloy dual-cylinder internal caliper, resulting in a brake assembly weight of 9.3kg-9.8kg. This represents a 36.4% reduction in weight compared to similar cast iron disc designs and a 43% reduction in weight compared to traditional brakes for the same vehicle model, achieving significant weight reduction. Furthermore, the disc body features a thin-walled annular structure with multiple bolt holes and lifting lugs along its edges for mechanical connection to the wheel hub or brake caliper bracket. Numerous rectangular ventilation holes (penetrating the disc's thickness) form a "three-dimensional ventilation network": the channels are staggered along the disc's circumference, guiding airflow through the disc during rotation and quickly dissipating heat generated during braking. The shape and density of the ventilation holes are aerodynamically optimized, balancing ventilation efficiency with disc structural strength (avoiding excessive perforation that could reduce rigidity).

[0029] This solution utilizes the high-temperature resistance of carbon ceramic materials (maintaining structural stability above 1000℃) to address the severe heat fade problem of traditional cast iron brake discs. The low density of carbon ceramic materials significantly reduces the wheel hub's rotational inertia, improving motor response speed and range. The low thermal conductivity of carbon ceramic materials reduces the transfer of braking heat to the wheel hub motor, protecting the motor's electronic control components. The three-dimensional ventilation holes on the disc create forced convection during disc rotation, increasing heat dissipation efficiency by more than 30% compared to solid discs, effectively suppressing heat fade. Simultaneously, the ventilation holes guide brake dust, reducing brake pad wear rate and extending the braking system's lifespan. The "thin-walled + rationally designed openings" design of the carbon ceramic ventilated brake disc 15 reduces weight by 40%-60% while ensuring torsional and impact resistance through material mechanics optimization (reinforced by carbon fiber). The edge lugs and bolt connections further ensure even stress distribution on the disc, avoiding the risk of cracking due to localized stress concentration.

[0030] The inner side of the ventilated brake disc 15 is engaged with the inner side of the brake caliper, and the outer side of the disc is rigidly connected to the rotating part of the hub motor through bolt holes, so as to achieve the coordination of "braking torque transmission" and "heat dissipation airflow circulation".

[0031] like Figure 6 As shown, a positioning and heat-insulating boss structure 34 is provided at the connection between the outer circumference of the ventilated brake disc 15 and the electric wheel housing 1. This boss structure 34 can ensure the positioning and assembly error of the ventilated brake disc 15. While ensuring assembly strength, the boss structure 34 can also reduce the contact area between the outer circumference of the ventilated brake disc 15 and the electric wheel housing 1, thereby reducing heat transfer. In addition, a heat-insulating gasket 33 is installed between the boss structure 34 and the electric wheel housing 1. The heat-insulating gasket 33 and the heat-insulating boss 34 correspond one-to-one to form a heat-insulating structure. In this embodiment, 12 heat-insulating structures are evenly distributed along the circumference of the ventilated brake disc 15. The thickness of the heat-insulating gasket 33 is 2mm. The heat-insulating gasket 33 is made of ceramic fiber board, and the thermal conductivity of this material is approximately 27 W·m. -1 ·℃ -1 Specific heat capacity is approximately 1000 J·kg -1 ·℃ -1 The thermal conductivity of the material used in carbon-ceramic brake discs is approximately 53.044 W·m. -1 ·℃ -1 Its specific heat capacity is approximately 0.806 J·kg⁻¹ -1 ·℃ -1 In other words, the specific heat capacity of the material used in the heat insulation pad 33 is much greater than that of the carbon ceramic material of the ventilated brake disc 15, while its thermal conductivity is lower than that of the carbon ceramic material of the ventilated brake disc 15. Therefore, the heat of the ventilated brake disc 15 is less likely to be transferred to the heat insulation pad 33, thus playing the role of isolating the ventilated brake disc 15 from transferring heat to the outer rotor 2 of the motor.

[0032] like Figure 7 and Figure 8 As shown, this design also includes a heat insulation baffle between the ventilation brake disc 15 and the motor dynamic seal 13. A heat insulation coating is applied to the supporting surface 4 of the motor stator 3 near the ventilation brake disc 15. The dynamic seal 13 mainly consists of an annular sealing cavity, core dynamic seal elements (sealing components adapted to the rotating and fixed interfaces, such as sealing rings and sealing rings, which are embedded in the structure), and a dedicated baffle (a plate-like structure that cooperates with the sealing elements). All components are precisely connected through circumferential bolt holes, central mounting holes, and other structures to ensure assembly coaxiality and operational stability. The heat insulation baffle is an annular or partially extended plate-like structure, arranged on the side of the dynamic seal element closest to the external environment, forming a physical protective barrier. Through the dual effects of directly blocking impurities and guiding airflow direction, it reduces the intrusion of dust, mud, and other contaminants into the sealing gap. To address the high-speed rotation and vibration characteristics of the hub motor's rotating components, the shape, thickness, and spacing between the heat insulation baffle and the sealing element can be mechanically optimized. This avoids interference with other components during rotation and ensures continuous protection under dynamic conditions. Simultaneously, the internal flow channel of the sealing cavity, in conjunction with the heat insulation baffle, guides fluid distribution, aiding in sealing and heat dissipation. In this design, the heat insulation baffle acts as a pre-protective layer, intercepting large particles, moisture, and other contaminants, reducing their direct erosion of dynamic sealing elements (such as lip seals and mechanical seal surfaces), lowering the wear rate of the seals, and significantly improving the reliability and service life of the sealing system under complex conditions such as wading and dust. The heat insulation baffle and dynamic seal 13 are integrated, separating the brake disc surface from the motor dynamic seal 13. This heat insulation baffle is composed of stacked stainless steel foils, with aerogel filling the spaces between the foils to effectively reflect heat radiation from the brake. In this embodiment, the heat insulation baffle is 5mm thick.

[0033] The heat insulation coating uses magnesium-aluminum alloy as the base material, and an Al2O3-SiO2 coating is plasma sprayed on the part of the stator support surface 4 near the brake. This coating plays a role in blocking the heat transfer from the brake and reflecting heat radiation, which helps to ensure that the motor can work normally under harsh braking conditions.

[0034] Through the optimized design of the above structure and materials, during braking, the heat generated by the ventilated brake disc 15 is blocked by the heat insulation pad 33 during the conduction to the hub electric wheel housing 1; the heat radiation generated by the brake is blocked by the heat insulation baffle on the passive seal 13, which also isolates some of the heat; the heat radiation of the brake is reflected by the heat insulation coating on the stator support surface 4; the ventilated brake disc 15 promotes airflow convection heat dissipation, and the frictional heat is quickly dissipated by the aluminum alloy brake caliper. While achieving lightweight design, it can effectively reduce the impact of the heat generated by the brake during braking on the permanent magnet of the motor, and has extremely high thermal isolation performance.

[0035] Applying this solution to practical applications ensures that the electric wheel has a compact structure, highly integrated components with a reasonable spatial arrangement, light weight, effectively blocks the transfer of heat from the brake disc to the motor, has higher driving torque density and braking torque density, high transmission efficiency, and fast response. It is well-suited for scenarios requiring efficient braking and drive integration, such as electric vehicles and electric motorcycles.

Claims

1. A hub-driven electric wheel structure with an integrated disc brake, characterized in that, The device includes an electric wheel housing (1), in which an outer rotor (2), a stator (3), a ventilated brake disc (15), and an aluminum alloy inner brake caliper are installed. A heat insulation device is provided between the outer circumference of the ventilated brake disc (15) and the electric wheel housing (1), and a heat insulation baffle is provided between the ventilated brake disc (15) and the motor dynamic seal (13). The aluminum alloy inner brake caliper is located in the inner circumference space of the ventilated brake disc (15), forming a brake assembly.

2. The hub direct-drive electric wheel structure with an integrated disc brake according to claim 1, characterized in that, The heat insulation device includes a boss structure (34) which is evenly distributed along the outer circumference of the ventilated brake disc (15). A heat insulation gasket (33) is installed between the boss structure (34) and the electric wheel housing (1).

3. The hub direct-drive electric wheel structure with an integrated disc brake according to claim 2, characterized in that, The thermal conductivity of the heat insulation pad (33) is lower than that of the ventilated brake disc (15), and the specific heat capacity of the heat insulation pad (33) is greater than that of the ventilated brake disc (15).

4. The hub direct-drive electric wheel structure with an integrated disc brake according to claim 3, characterized in that, The ventilated brake disc (15) is made of carbon ceramic material, and the heat insulation pad (33) is made of ceramic fiber material.

5. The hub direct-drive electric wheel structure with an integrated disc brake according to claim 1, characterized in that, The ventilated brake disc (15) is a thin-walled annular structure. Multiple ventilation holes are provided on the ventilated brake disc (15). Multiple lifting lugs are provided on the outer side wall of the ventilated brake disc (15). The lifting lugs are connected to the electric wheel housing (1) by flange bolts.

6. The hub direct-drive electric wheel structure with an integrated disc brake according to claim 1, characterized in that, The aluminum alloy inner clamp brake caliper includes a brake block (24) and a caliper body. The caliper body includes a caliper cylinder (23) and a caliper back (25) that are internally clamped on both sides of the ventilated brake disc (15). The caliper cylinder (23) and the caliper back (25) are connected by a caliper bracket (22).

7. The hub direct-drive electric wheel structure with an integrated disc brake according to claim 1, characterized in that, The heat insulation baffle is a ring-shaped or partially extended plate-shaped structure, arranged on the side of the dynamic sealing (13) element close to the external environment, forming a physical protective barrier.

8. The hub direct-drive electric wheel structure with an integrated disc brake according to claim 7, characterized in that, The heat insulation baffle is composed of stacked stainless steel foils, with aerogel filling the spaces between the stainless steel foils.

9. The hub direct-drive electric wheel structure with an integrated disc brake according to claim 1, characterized in that, The supporting surface (4) of the motor stator (3) is coated with a heat-insulating coating on the side near the ventilated brake disc (15) to block heat transfer from the ventilated brake disc (15) and reflect heat radiation.

10. A hub direct-drive electric wheel structure with an integrated disc brake according to claim 9, characterized in that, The substrate of the heat insulation coating is made of magnesium-aluminum alloy and is coated with Al2O3-SiO2 by plasma spraying.

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