Speed reduction type hub motor and braking method thereof

Abstract

The invention discloses a speed reduction type hub motor and a braking method thereof, and relates to the technical field of hub motors. The speed reduction type hub motor comprises an inner rotor motor, the inner rotor motor comprises a motor shell, a stator, a rotor, a rotor support and a motor output shaft, the rotor is fixed on the rotor support, and the rotor support is fixedly connected with the motor output shaft; the inner concave cavity is formed between the rotor bracket and the motor output shaft; and the speed reducer is embedded in the inner concave cavity. The invention further discloses a braking method applied to the speed reduction type hub motor. Based on the technical scheme disclosed by the invention, the mounting convenience of the hub motor can be improved, the braking response speed can be increased, the braking transmission efficiency and stability can be improved, and the controllability, comfort and safety of vehicle driving can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hub motors, and in particular to a reduction-type hub motor and a braking system and a braking method thereof. Background Art

[0002] Currently, in-wheel motors are primarily categorized as direct-drive and reduction-type. Direct-drive in-wheel motors often struggle to provide sufficient torque due to size and weight limitations. Reduction-type in-wheel motors, on the other hand, utilize a built-in reducer to effectively reduce the motor load while providing a more stable and powerful torque output for the vehicle.

[0003] In related technologies, reduction-type hub motors typically integrate a motor, reducer, and brake. However, due to structural redundancy, bulk, and low internal space utilization, these motors have a relatively large axial dimension, which not only makes installation more difficult but also indirectly affects transmission efficiency.

[0004] In addition, vehicles using related reduction-type hub motors are often prone to ignoring the driver's intentions and are generally unable to personalize the distribution of braking torque, which not only affects the driving experience, but also affects the vehicle's handling and safety. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies and propose a reduction wheel hub motor and a braking method thereof to solve the technical problems in the prior art of reduction wheel hub motors such as structural redundancy, difficulty in installation, low transmission efficiency and impact on vehicle controllability and safety.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a reduction-type hub motor, comprising: An inner rotor motor, comprising a motor housing, a stator, a rotor, a rotor support, and a motor output shaft, wherein the rotor is fixed to the rotor support, and the rotor support is fixedly connected to the motor output shaft; a concave chamber formed between the rotor support and the motor output shaft; and The reducer is embedded in the concave chamber and is used to connect the motor output shaft and the wheel.

[0007] In some embodiments, a brake is further included, wherein the brake is mounted on an end of the motor output shaft away from the reducer, and the brake includes: brake housing; a brake output shaft, disposed on the brake housing and configured to output a braking torque; and a friction brake assembly, disposed inside the brake housing and connected to the brake output shaft, for generating a braking torque and acting on the brake output shaft; Wherein, a brake control component is provided at the connection between the brake output shaft and the motor output shaft, for controlling the transmission of the braking torque on the brake.

[0008] In some embodiments, the brake control assembly includes: a first end face gear, slidably disposed on the motor output shaft; a second end face gear fixedly disposed on the brake output shaft and configured to engage with the first end face gear; and The pushing assembly is connected to the first end face gear and is used to drive the first end face gear to approach or move away from the second end face gear.

[0009] In some embodiments, the pushing assembly includes: movable parts; a piston mechanism connected to the movable member and configured to drive the movable member to move along the motor output shaft; and An elastic reset member is provided on the piston mechanism and is connected to the first end face gear, and is used for driving the first end face gear to reset.

[0010] In a second aspect, the present invention further provides a braking method for a reduction-type hub motor, which is applied to the above-mentioned reduction-type hub motor, comprising: Get vehicle information; Judging and determining a braking scenario of the vehicle based on the vehicle information; and Adopting a corresponding braking strategy to brake the reduction wheel hub motor according to the vehicle information and the braking scenario; The braking scenarios include straight-line braking and curve braking; the braking strategies include full electric braking, non-regenerative electric braking, electromechanical composite braking, and mechanical braking.

[0011] In some embodiments, “judging and determining a braking scenario of the vehicle based on the vehicle information” includes: Obtain steering wheel angle and driving path curvature information; When the steering wheel angle and the driving path curvature are respectively greater than corresponding preset values, determining that the braking scenario of the vehicle is cornering braking; and When the steering wheel angle or the driving path curvature is less than or equal to a corresponding preset value, it is determined that the braking scenario of the vehicle is straight-line braking.

[0012] In some embodiments, “adopting a corresponding braking strategy to brake the reduction-type in-wheel motor according to the vehicle information and the braking scenario” includes: Obtain vehicle brake pedal opening, battery SOC, vehicle speed, and vehicle braking deceleration information; When the vehicle brake pedal opening is less than or equal to a corresponding preset value, the reduction wheel hub motor is braked by a full electric braking method; When the vehicle brake pedal opening is greater than a corresponding preset value, the battery SOC is greater than or equal to a corresponding preset value, and the vehicle speed and the vehicle braking deceleration do not exceed corresponding preset values, braking the reduction-type in-wheel motor using non-regenerative electric braking; and When the vehicle brake pedal opening is greater than the corresponding preset value, the battery SOC is less than the corresponding preset value, and the vehicle speed and the vehicle braking deceleration are both greater than the corresponding preset values, electromechanical composite braking or mechanical braking is used to brake the reduction hub motor.

[0013] In some embodiments, “adopting a corresponding braking strategy to brake the reduction-type in-wheel motor according to the vehicle information and the braking scenario” further includes: When the vehicle meets the conditions for electromechanical composite braking or mechanical braking, obtain vehicle braking intensity information; When the braking intensity is less than or equal to a first threshold, mechanical braking is used to brake the reduction hub motor; When the braking intensity is greater than a first threshold value and less than a second threshold value, the reduction-type hub motor is braked by electromechanical composite braking; and When the braking intensity is greater than or equal to a second threshold, mechanical braking is used to brake the reduction hub motor.

[0014] In some embodiments, “adopting a corresponding braking strategy to brake the reduction-type in-wheel motor according to the vehicle information and the braking scenario” further includes: Determine the vehicle's current braking scenario; and According to the current braking scenario of the vehicle, the corresponding front and rear axle braking force distribution strategy is adopted to distribute the braking force of each of the reduction-type hub motors on the front and rear axles of the vehicle; The front and rear axle braking force distribution strategy includes a straight-line braking distribution mode and a cornering braking distribution mode.

[0015] In some embodiments, when the reduction wheel hub motor is braked using electromechanical composite braking, the electric braking force and mechanical braking force of the reduction wheel hub motor are distributed according to the regenerative braking participation ratio; wherein, the regenerative braking participation ratio is obtained according to fuzzy control rules.

[0016] Compared with the existing technology, the present invention provides a reduction-type hub motor. By forming an inner concave chamber between the rotor bracket and the motor output shaft and embedding the reducer as a whole in the inner concave chamber, the reducer and the inner rotor motor are deeply integrated, making the overall structure of the hub motor more compact and helping to reduce its axial size. It not only improves the installation convenience, but also indirectly accelerates the braking response speed and improves the braking torque transmission efficiency and stability.

[0017] At the same time, the present invention also provides a braking method for a reduction wheel hub motor, which can adopt corresponding braking strategies to brake the reduction wheel hub motor according to vehicle information and braking scenarios, realize reasonable distribution of braking force, combine the advantages of electric braking and mechanical braking, ensure the smoothness and comfort of the braking process, and improve the braking safety and driving experience of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a cross-sectional schematic diagram of the overall structure of a reduction-type hub motor according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a brake control assembly according to an embodiment of the present invention; Figure 3 The figure is a flow chart of a braking method for a reduction-type hub motor in one embodiment of the present invention.

[0019] Explanation of the accompanying drawings: 1. Motor housing; 110. Housing; 120. End cover; 121. Recess; 122. Extension; 2. Stator; 3. Rotor; 4. Motor output shaft; 5. First bearing; 6. Second bearing; 7. Rotor bracket; 8. Sun gear; 9. Planetary gear; 10. Ring gear; 11. Planet carrier; 12. Third bearing; 13. First oil seal; 14. Second oil seal; 15. Third oil seal; 16. Fourth oil seal; 17. Brake housing; 18. Brake output shaft; 19. Friction brake assembly; 20. Brake control assembly; 21. First end face gear; 22. Second end face gear; 23. Push assembly; 231. Push plate; 232. Piston mechanism; 233. Return spring; 234. Oil inlet pipe. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] In order to solve the above technical problems, the present invention provides a reduction-type hub motor and a braking method thereof, which can not only improve the installation convenience of the hub motor, accelerate the braking response speed, improve the braking transmission efficiency and stability, but also help to improve the vehicle driving controllability, comfort and safety.

[0022] Example 1: See also Figure 1 , Figure 1 This is a cross-sectional schematic diagram of the overall structure of a reduction hub motor in one embodiment of the present invention. The reduction hub motor includes an inner rotor motor, a reducer, and a brake. The inner rotor motor is integrated and installed inside the reduction hub motor, while the brake is external to the inner rotor motor.

[0023] Specifically, the inner rotor motor is preferably a permanent magnet synchronous inner rotor motor, comprising a motor housing 1, a stator 2, a rotor 3, and a motor output shaft 4. The motor housing 1 comprises a housing 110 and an end cap 120. The housing 110 as a whole can be configured as a hollow cylindrical structure, or other shapes, without specific limitation. One side of the housing 110 is open, and the end cap 120 as a whole is detachably fixed to the side of the housing 110 where the opening is located. The stator 2 and its windings are fixedly mounted inside the motor housing 1. The motor output shaft 4 is rotatably mounted inside the motor housing 1 via a first bearing 5 and a second bearing 6. The stator 2 and the motor output shaft 4 are coaxially arranged inside the motor housing 1.

[0024] To install the rotor 3 and its windings, a rotor bracket 7 is further provided inside the motor housing 1. The rotor bracket 7 can be configured as a disc-shaped structure and is integrally sleeved on the motor output shaft 4. It can be removably fixed to the shoulder of the motor output shaft 4 via pins, allowing the rotor bracket 7 to rotate synchronously with the motor output shaft 4. The rotor bracket 7 is coaxial with the motor output shaft 4 and is located just inside the stator 2. Correspondingly, the rotor 3 and its windings can be integrally fixed to the outer wall of the rotor bracket 7 and are positioned opposite the stator 2. Thus, when the inner rotor motor is started, the rotor 3 can drive the rotor bracket 7 to rotate, and the rotor bracket 7 further drives the motor output shaft 4 to rotate.

[0025] In this embodiment, in order to install the above-mentioned reducer, the side of the above-mentioned rotor bracket 7 close to the end cover 120 is concave and together with the motor output shaft 4 forms a concave chamber. The reducer can be embedded as a whole in the concave chamber, thereby realizing deep integration of the reducer and the inner rotor motor.

[0026] Specifically, the reducer can be a planetary gear reducer. The planetary gear reducer has a high transmission efficiency and a relatively large output torque. Its application here can not only ensure the effective transmission of the power of the inner rotor motor, but also improve the overall operation stability and impact resistance of the hub motor.

[0027] The reducer includes a sun gear 8, a plurality of planetary gears 9, a ring gear 10, and a planet carrier 11. The sun gear 8 can be coaxially fixed to the motor output shaft 4 by means of a key connection, so that the sun gear 8 can rotate synchronously with the motor output shaft 4. The planet carrier 11 is rotatably mounted on the inner side of the motor housing 1, and a plurality of planetary gears 9 are rotatably mounted on the planet carrier 11, distributed around the circumference of the sun gear 8, and meshing with the sun gear 8. The ring gear 10 can be fixed to the motor housing 1, so that it remains relatively stationary with the motor housing 1 during operation; at the same time, the ring gear 10 is integrally mounted on the outer side of each planetary gear 9 and meshes with each planetary gear 9.

[0028] In actual operation, when the motor output shaft 4 starts to rotate, the motor output shaft 4 can drive the planetary gears 9 to rotate through the sun gear 8. While rotating, the planetary gears 9 will also revolve around the sun gear 8, thereby further driving the planet carrier 11 to rotate inside the motor housing 1.

[0029] It should be noted that the number of the planetary gears 9 can be 2, 3 or 4, and no specific limitation is made thereto as long as the transmission stability is ensured.

[0030] In this embodiment, to mount the ring gear 10, the end cap 120 is opened in the middle and recessed toward the inside of the housing 110 to form a recessed portion 121. The recessed portion 121 is formed into a basin-like structure. An extension 122 is vertically formed at the bottom of the recessed portion 121, with a reserved space between the extension 122 and the inner sidewall of the recessed portion 121. This allows the ring gear 10 to be completely secured to the bottom of the recessed portion 121, thereby achieving installation of the ring gear 10.

[0031] Correspondingly, the planet carrier 11 is entirely sleeved on the motor output shaft 4, with its outer side extending into the reserved space. A rotational connection is formed between the third bearing 12 and the inner wall of the recess 121, thereby enabling the planet carrier 11 to flexibly rotate within the recess 121. The planetary gears 9 are disposed on the side of the planet carrier 11 closest to the sun gear 8.

[0032] In another embodiment, to achieve transmission between the in-wheel motor and the wheel, multiple pins for connecting to the wheel can be provided on the side of the planetary carrier 11 facing away from the planetary gears 9. In this way, the planetary carrier 11 is connected to the wheel via the pins. When the motor output shaft 4 rotates, the planetary gears 9 drive the planetary carrier 11 to rotate around the sun gear 8, which in turn drives the wheel, thus achieving transmission between the inner rotor motor and the wheel.

[0033] It's understandable that the end cap 120 doesn't employ a traditional cover plate structure, but rather serves as a necessary condition for the installation of certain components. In this case, the end cap 120 and the planetary carrier 11 effectively form a cover plate, and the inner rotor motor and reducer in this embodiment can be considered to share the end cap 120. This helps further enhance the compactness of the hub motor structure.

[0034] In this embodiment, in order to improve the stability and reliability of the hub motor operation, the interior of the reducer can be lubricated by oil immersion lubrication. In order to avoid leakage of lubricating oil and ensure the sealing and independence of each chamber, the interior of the motor housing 1 is sealed.

[0035] Specifically, a first oil seal 13 is provided between the end cover 120 and the planetary carrier 11, a second oil seal 14 is provided between the planetary carrier 11 and the motor output shaft 4, a third oil seal 15 is provided between the recessed portion 121 on the end cover 120 and the motor output shaft 4, and a fourth oil seal 16 is provided at the connection between the ring gear 10 and the recessed portion 121. The first oil seal 13, the second oil seal 14, the third oil seal 15, and the fourth oil seal 16 are preferably rotary oil seals.

[0036] See also Figure 1 and Figure 2 The above-mentioned brake is entirely arranged outside the motor housing 1. It is preferably a wet brake and is entirely located at the end of the motor output shaft 4 away from the reducer. The brake includes a brake housing 17, a brake output shaft 18 and a friction brake assembly 19.

[0037] The brake output shaft 18 is disposed inside the brake housing 17. The friction brake assembly 19, which may be a friction plate, is disposed inside the brake housing 17 and connected to the brake output shaft 18 to generate a braking torque and apply it to the brake output shaft 18. A pressure oil port is also provided on the brake housing 17.

[0038] It should be noted that the specific structure of the above-mentioned brake belongs to the existing technology in this field and is not the focus of the present invention. The present invention only uses this wet brake here, so it will not be described in detail here.

[0039] In order to address the belt resistance problem existing in the existing reduction hub motor, a brake control component 20 is further provided between the above-mentioned brake output shaft 18 and the motor output shaft 4 in this embodiment. The brake control component 20 can control the connection or disconnection between the brake output shaft 18 and the motor output shaft 4, thereby controlling the transmission of the braking torque on the brake.

[0040] Specifically, the brake control assembly 20 includes a first face gear 21, a second face gear 22, and a push assembly 23. The first face gear 21 is slidably mounted on the motor output shaft 4 and is located near the end of the motor output shaft 4. The second face gear 22 is fixedly mounted on the end of the brake output shaft 18 near the motor output shaft 4. The push assembly 23 is connected to the first face gear 21 and is used to drive the first face gear 21 toward or away from the second face gear 22.

[0041] In one embodiment, the push assembly 23 includes a movable member, a piston mechanism 232, and an elastic return member. The movable member may be a push plate 231, which is connected to the piston mechanism 232 and may be disposed on the side of the first face gear 21 facing away from the second face gear 22. The piston mechanism 232 is connected to an oil inlet pipe 234, which communicates with the pressure oil port on the brake housing 17 to maintain consistent pressure between the two. The elastic return member may be a return spring 233, which may be disposed on the piston mechanism 232, with one end connected to the first face gear 21.

[0042] When the brake receives a braking signal, pressurized oil enters the brake housing 17 and piston mechanism 232 through the pressure oil port and oil inlet pipe 234, respectively. Under the action of the pressurized oil, the friction brake assembly 19 generates a braking torque and applies this braking torque to the brake output shaft 18. Simultaneously, pressurized oil enters the piston mechanism 232 through the oil inlet pipe 234. The piston mechanism 232, via the push plate 231, pushes the first end gear 21 to slide along the motor output shaft 4 and engage the second end gear 22. As a result, the braking torque on the brake output shaft 18 is transmitted to the motor output shaft 4 via the first and second end gears 21, 22, thereby braking the motor output shaft 4. When the brake signal disappears, the oil pressure in the piston mechanism 232 is restored, the braking torque on the brake disappears, and under the action of the return spring 233, the first end gear 21 moves away from the second end gear 22, disengaging the two.

[0043] It can be understood that after the braking signal disappears, the brake output shaft 18 and the motor output shaft 4 are disconnected by the brake control component 20, so the belt resistance in the brake will not act on the motor output shaft 4, thereby achieving zero belt resistance, reducing power consumption and loss, solving the heat dissipation difficulties of the hub motor, and reducing brake wear.

[0044] In order to better understand the present invention, the following Figure 1 and Figure 2 The technical solution of Example 1 is described in detail: In this embodiment, by forming a concave chamber between the rotor bracket 7 and the motor output shaft 4 and installing the planetary gear reducer within this chamber, the reducer and inner rotor motor are deeply integrated. This makes the in-wheel motor more compact, helps reduce its axial dimension, and improves installation convenience. It also indirectly accelerates braking response and enhances braking torque transmission efficiency and stability. The planetary gear reducer's high transmission efficiency and high torque output ensure effective power transmission from the in-wheel motor, while its smooth operation and strong impact resistance further enhance the system's reliability and service life.

[0045] At the same time, the wet brake is installed as a whole on the outside of the motor housing 1, and the connection status of the motor output shaft 4 and the brake output shaft 18 is controlled by the brake control component 20. This not only reduces the impact of braking heat on the hub motor body and ensures the stable operation and long-term reliability of the hub motor, but also realizes effective control of the braking torque transmission on the brake, achieves zero belt resistance, significantly improves the efficiency and response speed of the brake, helps to improve the performance of the brake, and extends its service life.

[0046] Example 2: See also Figure 3 , Figure 3 The figure is a flow chart of a braking method for a reduction-type hub motor according to an embodiment of the present invention.

[0047] A braking method for a reduction wheel hub motor is used to implement braking control on the reduction wheel hub motor, thereby improving the stability and reliability of braking torque transmission and indirectly improving the comfort, controllability and safety of the vehicle.

[0048] It can be understood that this braking method can be applied to reduction hub motors, which are usually used in automobiles. Automobiles usually include multiple reduction hub motors as mentioned above, and multiple reduction hub motors can be respectively arranged at the four wheels on the front and rear axles of the automobile to realize driving and braking functions for the wheels.

[0049] In this embodiment, a braking method for a reduction-type hub motor includes: Get vehicle information; Judging and determining the vehicle's braking scenario based on vehicle information; Adopting a corresponding braking strategy to brake the reduction wheel hub motor according to vehicle information and braking scenarios; Among them, braking scenarios include straight-line braking and cornering braking; braking strategies include full electric braking, non-regenerative electric braking, electromechanical composite braking and mechanical braking.

[0050] In this embodiment, when determining the specific braking strategy for the deceleration in-wheel hub motor, the specific braking scenario is first determined based on vehicle information: whether it is straight-line braking or cornering braking. After the braking scenario is determined, different braking strategies are corresponding to different braking scenarios. These braking strategies may include full electric braking, non-regenerative electric braking, electromechanical combined braking, and mechanical braking. Full electric braking utilizes the reversibility principle of the motor to convert mechanical energy into electrical energy to achieve deceleration, with energy recovery occurring during this process. Non-regenerative electric braking utilizes electric braking without energy recovery. Electromechanical combined braking utilizes both mechanical and electric braking. Mechanical braking utilizes mechanical structure to transmit braking force.

[0051] Specifically, when acquiring vehicle information, the vehicle information that needs to be acquired includes at least the steering wheel angle and the curvature information of the vehicle's travel path. The steering wheel angle and the curvature information of the vehicle's travel path can be used to judge and determine the vehicle's braking scenario. The specific judgment method is as follows: When the steering wheel angle and the curvature of the driving path are respectively greater than the corresponding preset values, it can be determined that the current braking scenario of the vehicle is cornering braking; When the steering wheel angle or the curvature of the driving path is less than or equal to the corresponding preset value, it can be determined that the current braking scenario of the vehicle is straight-line braking.

[0052] It is understood that the aforementioned steering wheel angle and driving path curvature information can be obtained from the vehicle's vehicle control system. The preset values ​​for the steering wheel angle and driving path curvature can be flexibly set for different vehicles while ensuring driving safety. For example, in one embodiment, the preset values ​​for the aforementioned steering wheel angle can be 8°, 9°, or 10°, while the driving path curvature can be 0.1m, 0.15m, etc., without limitation to these specific values.

[0053] At the same time, when determining cornering braking, it is preferred to control the steering wheel angle and the driving path curvature to be greater than the corresponding preset values. That is, only when the steering wheel angle and the driving path curvature are both greater than the corresponding preset values ​​can it be determined that the vehicle is in a cornering braking state.

[0054] Similarly, when determining straight-line braking, when any one of the values ​​of the steering wheel angle and the curvature of the driving path satisfies the condition of being less than or equal to the corresponding preset value, it can be determined that the vehicle is currently in the straight-line braking state.

[0055] Understandably, for a vehicle, the braking force distribution between the front and rear axles differs between straight-line braking and cornering braking. Even the braking force from the in-wheel motors can be different for each wheel. Therefore, correctly determining the vehicle's current braking scenario and then allocating braking force based on the braking strategy corresponding to each braking scenario can more effectively distribute the vehicle's braking force to ensure controllability and safety.

[0056] At the same time, the definition of braking scenarios in this embodiment only includes straight-line braking and cornering braking. However, in actual applications, the braking scenarios can be further divided as needed. For example, straight-line braking can be divided into straight-line braking for daily commuting environments and straight-line braking for racing environments; correspondingly, cornering braking can also be similarly divided.

[0057] In this embodiment, when acquiring vehicle information, the vehicle information that needs to be acquired may also include vehicle brake pedal opening, battery SOC, vehicle speed, and vehicle braking deceleration information.

[0058] Based on the acquired vehicle brake pedal opening, battery SOC, vehicle speed, and vehicle braking deceleration information, the above braking strategy may include: Obtain vehicle brake pedal opening, battery SOC, vehicle speed, and vehicle braking deceleration information; When the vehicle brake pedal opening is less than or equal to the corresponding preset value, the reduction wheel hub motor is braked by full electric braking; When the vehicle brake pedal opening is greater than the corresponding preset value, the battery SOC is greater than or equal to the corresponding preset value, and the vehicle speed and vehicle braking deceleration do not exceed the corresponding preset values, the reduction wheel hub motor is braked using non-regenerative electric braking; When the vehicle brake pedal opening is greater than the corresponding preset value, the battery SOC is less than the corresponding preset value, and the vehicle speed and vehicle braking deceleration are both greater than the corresponding preset values, electromechanical composite braking or mechanical braking is used to brake the reduction hub motor.

[0059] The vehicle's brake pedal travel is related to the specific circumstances in which the driver steps on the brake pedal. It refers to the vertical displacement of the brake pedal from its initial free position to the moment it is fully depressed. This parameter reflects the driver's control of the braking system. Physically, it is the mapping between pedal travel and brake fluid pressure, directly affecting braking force transmission efficiency and vehicle deceleration performance. Battery SOC refers to the percentage of the vehicle's remaining battery charge to its total available capacity, ranging from 0% (fully discharged) to 100% (fully charged).

[0060] Vehicle speed reflects the vehicle's current speed, while braking deceleration reflects how quickly the vehicle decelerates as a result of the driver's application of the brake pedal. It also reflects the driver's desired deceleration rate. After the driver applies the brake pedal, for the same braking deceleration, the faster the current speed, the longer it takes to brake. Conversely, for the same initial speed, the greater the braking deceleration, the shorter the braking time.

[0061] In actual applications, when the vehicle is driving normally, if the driver encounters a routine braking situation, such as a traffic light, normal deceleration of the vehicle in front when following, etc., the driver generally steps on the brake pedal with a small amplitude; at this time, since the response speed of electric braking is relatively fast and it is fully capable of meeting conventional braking needs, the vehicle can be braked by full electric braking.

[0062] For this situation, through a large number of repeated tests, an average value of the vehicle brake pedal opening at this time can be determined, and then this average value can be set as the preset value of the vehicle brake pedal opening; when the vehicle brake pedal opening is less than or equal to the preset value, it means that the vehicle is most likely in a normal braking situation; at this time, the full electric braking method is sufficient to cope with this braking situation.

[0063] When the vehicle brake pedal opening is greater than the above preset value, it means that the braking situation faced by the driver may exceed the above conventional braking situation and may require relatively more efficient braking means. The specific braking strategy to be adopted can be further determined based on the battery SOC, vehicle speed and vehicle braking deceleration information.

[0064] Among them, the battery SOC reflects the current remaining power of the vehicle battery. When the remaining power is sufficient, non-regenerative electric braking can be considered to avoid the battery SOC value exceeding the numerical range of the battery during normal operation due to energy recovery; the vehicle speed reflects the current speed of the vehicle, and the vehicle braking deceleration reflects the speed of the vehicle braking; the faster the speed, the greater the total braking force required for the vehicle to brake; correspondingly, the vehicle braking deceleration will generally be greater.

[0065] Based on the above analysis, when the vehicle brake pedal opening is greater than its preset value, that is, the conventional full electric braking braking strategy fails, the vehicle's braking logic can be: under the premise of not exceeding the braking capacity of non-regenerative electric braking, due to the faster response speed of electric braking, it is preferred to use non-regenerative electric braking; when it exceeds the scope of non-regenerative electric braking, you can further choose to use electromechanical composite braking or mechanical braking for braking.

[0066] Among them, the so-called "beyond the braking capacity scope without regenerative electric braking" can actually include the following two situations, namely, the braking capacity without regenerative electric braking cannot meet the vehicle's safe braking requirements, or the battery SOC is relatively low and energy recovery can be performed.

[0067] It is understandable that, on the one hand, when the braking capacity of non-regenerative electric braking cannot meet the needs of safe braking of the vehicle, of course, a more effective braking method is needed for braking; on the other hand, when the battery SOC is relatively low, energy recovery will not affect the normal operation of the battery, so even if the electromechanical composite braking method is adopted, the electric braking part of the electromechanical composite braking can also be carried out by energy recovery.

[0068] Specifically, when the vehicle brake pedal opening is greater than its preset value, the vehicle braking mode includes at least the following situations: When the battery SOC is greater than or equal to the corresponding preset value, and the vehicle speed and vehicle braking deceleration are both less than or equal to the corresponding preset values, the vehicle speed is slow and the driver's braking demand is relatively low. Since energy recovery may affect the normal operation of the battery, the vehicle can be braked without regenerative electric braking.

[0069] When the battery SOC is greater than or equal to the corresponding preset value, and the vehicle speed and vehicle braking deceleration are both greater than the corresponding preset values, due to the high vehicle speed, the driver's braking demand is relatively high. To ensure safety, it is preferred to use electromechanical composite braking for braking; and the electric braking part of the electromechanical composite braking can be performed without energy recovery.

[0070] When the battery SOC is less than its preset value, and the vehicle speed and braking deceleration are both less than or equal to the corresponding preset values, the vehicle speed is slow and the driver's braking demand is relatively low, so electromechanical hybrid braking can be used. Furthermore, since energy recovery does not affect the normal operation of the battery, the electric braking portion of the electromechanical hybrid braking can be performed using energy recovery.

[0071] If the battery SOC is less than its preset value, and both the vehicle speed and braking deceleration are greater than their corresponding preset values, the vehicle is moving at a high speed and the driver's braking demand is relatively high. To ensure safety, electromechanical or mechanical braking is preferred. Furthermore, since energy recovery does not affect the normal operation of the battery, when electromechanical braking is used, the electric braking portion of the electromechanical braking can be performed using energy recovery.

[0072] Among them, when the vehicle adopts electromechanical composite braking for braking, the braking strategy of the electromechanical composite braking can be mainly electric braking and supplemented by mechanical braking, and the two work together to achieve braking.

[0073] It can be understood that when the braking strategy adopted includes electric braking, whether the electric braking part performs energy recovery can be determined based on the vehicle's current battery SOC value; when the battery SOC is greater than or equal to its preset value, the electric braking part does not perform energy recovery; and when the battery SOC is less than its preset value, the electric braking part can perform energy recovery.

[0074] At the same time, the preset values ​​of the above-mentioned vehicle brake pedal opening, battery SOC, vehicle speed and vehicle braking deceleration can be flexibly set as needed, for example, they can be determined through a large number of repeated tests, and there is no specific limitation on this.

[0075] Moreover, for any one of the numerical values, two or more preset values ​​can be set simultaneously. Taking the battery SOC as an example, two preset values ​​can be set: a first preset value and a second preset value. The first preset value can be set as the critical value at which energy recovery does not affect the normal operation of the battery, and the second preset value can be set as the critical value of the vehicle's driving power demand. In this way, when the battery SOC reaches the first preset value, the hub motor no longer performs regenerative braking to avoid overcharging; and when the battery SOC is lower than the second preset value, the electric braking function can be completely turned off, and the vehicle braking relies entirely on mechanical braking to ensure the minimum driving power of the vehicle. Similarly, multiple preset values ​​can be set for other parameters to achieve multi-speed control, which will not be repeated here.

[0076] In this embodiment, when the vehicle is in a straight-line braking scenario and the vehicle meets the above-mentioned conditions for electromechanical combined braking or mechanical braking to be effective, in order to further determine which braking method the vehicle adopts, the above-mentioned braking strategy also includes: Obtain vehicle braking strength information; When the braking intensity is less than or equal to the first threshold, mechanical braking is used to brake the reduction hub motor; When the braking intensity is greater than the first threshold and less than the second threshold, the reduction wheel hub motor is braked by electromechanical composite braking; When the braking intensity is greater than or equal to the second threshold, mechanical braking is used to brake the reduction hub motor.

[0077] Specifically, braking intensity is a core indicator for measuring vehicle braking performance. It is defined as the ratio of vehicle deceleration to the acceleration due to gravity and reflects the efficiency of braking force distribution and energy conversion. Based on the definition of braking intensity, the smaller the vehicle's braking deceleration, the lower the braking intensity.

[0078] Therefore, when the braking intensity is less than or equal to the first threshold, it means that the current vehicle braking deceleration is small and the driver's braking demand is relatively low, and mechanical braking can be used to brake the reduction wheel hub motor.

[0079] When the braking intensity exceeds the second threshold, it indicates that the vehicle's braking deceleration is high and the driver's braking demand is relatively high. Therefore, mechanical braking is preferred for braking the in-wheel motors. However, unlike the above situation, the full mechanical braking capacity can be utilized to ensure braking safety.

[0080] When the braking intensity is greater than the first threshold and less than the second threshold, it indicates that the vehicle's deceleration is relatively moderate and the driver's braking demand is also relatively moderate. Therefore, electromechanical hybrid braking can be used to brake the deceleration in-wheel motor. This takes advantage of the fast response of electric braking and the high reliability of mechanical braking. In this case, electric braking can be used as the primary braking method, with mechanical braking as a supplement.

[0081] It is understood that the first and second thresholds for braking intensity can be set as needed. For example, in one embodiment, the first threshold can be set to 0.1 and the second threshold can be set to 0.7. Of course, based on a large number of repeated tests and to ensure safety, the specific values ​​are not limited.

[0082] Meanwhile, when the braking intensity exceeds the second threshold, the vehicle's current braking deceleration is high, indicating that the driver's braking demand is extremely strong, which can be understood as the vehicle triggering emergency braking mode. In this case, for safety reasons, mechanical braking is preferably used, and the mechanical braking capacity can be fully utilized.

[0083] Similarly, for the cornering braking scenario, the braking strategy can also be set in the same manner as above, which will not be repeated here.

[0084] In another embodiment, considering that braking force distribution varies across the vehicle's wheels during cornering, a more refined braking force distribution is required. Therefore, the braking strategy for cornering scenarios preferably utilizes electromechanical hybrid braking, controlling the ratio of electric and mechanical braking to determine the braking method used. In this case, when the electric braking ratio is 0, the vehicle effectively uses mechanical braking; when the mechanical braking ratio is 0, the vehicle effectively uses electric braking.

[0085] In this embodiment, after determining the braking method used by the vehicle, it is necessary to further determine the braking force distribution method of the front and rear axles of the vehicle. Therefore, the above braking strategy also includes: Determine the vehicle's current braking scenario; According to the vehicle's current braking scenario, the corresponding front and rear axle braking force distribution strategy is used to distribute the braking force to the reduction hub motors on the front and rear axles of the vehicle; Among them, the front and rear axle braking force distribution strategy includes straight-line braking distribution mode and cornering braking distribution mode.

[0086] Specifically, according to the previous explanation, there are definitely differences in the specific forms of power distribution between the front and rear axles of the vehicle in straight-line braking scenarios and cornering braking scenarios. Especially for cornering braking scenarios, the braking force distribution may need to be specific to the reduction hub motor of each wheel. Therefore, when determining the specific braking force distribution form, it is necessary to first determine the current braking scenario of the vehicle and adopt the corresponding braking force distribution strategy based on the braking scenario, that is, determine whether to adopt the straight-line braking distribution mode or the cornering braking distribution mode based on the specific braking scenario.

[0087] In one embodiment, the straight-line braking distribution mode includes distributing the braking forces on the front and rear axles of the vehicle according to a braking force distribution coefficient between the front and rear axles of the vehicle.

[0088] Specifically, the above-mentioned vehicle front and rear axle braking force distribution coefficient can be calculated based on vehicle dynamics analysis and the ideal braking force distribution curve (I curve), as follows: When braking on a straight road, ignoring the vehicle's rolling resistance moment, air distance, and inertia moment, the braking force distribution is calculated based on vehicle dynamics analysis and the ideal braking force distribution curve (I curve):

[0089] Where, is the vehicle gravity; is the vehicle mass; is the height of the vehicle's center of mass; are the distances from the center of mass to the front and rear axles respectively; is the wheelbase; Braking force for the front axle; Rear axle braking force.

[0090] In actual application, in order to maintain the driver's "braking" feeling, the front and rear axle braking forces are distributed according to a certain ratio and as close to the I curve as possible. The front and rear axle braking force distribution coefficient is , the calculation formula is:

[0091] in, is the total braking force.

[0092] The utilization adhesion coefficient of the front and rear axles is:

[0093]

[0094] in, is the adhesion coefficient; is the braking intensity, which is defined as:

[0095] In the above formula, is the vehicle speed, and g is the acceleration due to gravity.

[0096] Combining the front and rear axle adhesion coefficients and the GB12676-2014 braking regulations, the front and rear axle braking force distribution coefficients of the vehicle under the constraints of the ECE regulations are obtained. The value range is:

[0097] Based on this, the range of the front and rear axle braking force distribution coefficient can be calculated.

[0098] It is understandable that in actual application, the front and rear axle braking force distribution coefficients can be set within the range of the front and rear axle braking force distribution coefficients according to the requirements. For example, in one embodiment, the front and rear axle braking force distribution coefficients are The value can be 0.6. After determining the value of the front and rear axle braking force distribution coefficient, the braking force of the front and rear axles can be distributed according to the coefficient.

[0099] In one embodiment, the above-mentioned cornering braking distribution mode includes: outputting the vehicle four-wheel torque according to the braking force initial distribution module and the additional yaw moment control module, and calculating the braking force distribution of the four wheels.

[0100] Specifically, the method for obtaining the vehicle braking force initial distribution module is as follows: When a vehicle brakes on a curve, the vertical loads on each wheel are transferred. For example, when the vehicle brakes on a left turn, the vertical loads on the four wheels are as follows:

[0101] Where, 、 、 、 are the vertical loads on the left front wheel, right front wheel, left rear wheel, and right rear wheel respectively; are the distances between the center of mass of the vehicle and the front and rear axles respectively; is the acceleration due to gravity; are the longitudinal and lateral accelerations of the car respectively; is the vehicle mass; is the wheelbase; is the height of the center of mass; For wheelbase.

[0102] When a vehicle brakes in a curve, the load is transferred between the front and rear axles and the left and right wheels on the same axle. At this time, the vertical loads on the four wheels are different. If all four wheels are to reach the adhesion limit at the same time, the traction coefficient of each wheel should meet the following requirements:

[0103] Where, are the traction coefficients of the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively, which are equivalent to:

[0104] in, 、 、 、 The braking forces of the left front wheel, right front wheel, left rear wheel and right rear wheel are respectively. When the car brakes, the deceleration is first determined by the driver's desired Calculate the braking force required for the car , then The braking force is distributed to the four wheels in the proportional relationship shown in the above formula. The initial distribution of the vehicle's cornering braking force is as follows:

[0105]

[0106] In this embodiment, the method for obtaining the additional yaw moment control module of the vehicle is as follows: Establish a two-degree-of-freedom vehicle dynamics model. The yaw rate of the vehicle during steady-state operation , center of mass side slip angle is a fixed value, so we can make and is 0. In addition, the lateral acceleration of the car during the turning process is limited by the road adhesion condition, that is, , the ideal yaw angular velocity is:

[0107] Where, is the ground adhesion coefficient; is a symbolic function; is the vehicle stability factor; is the front wheel turning angle; is the longitudinal speed.

[0108] Among them, the vehicle stability factor The calculation formula is:

[0109] Where, are the front and rear axle cornering stiffnesses, respectively.

[0110] Similarly, the ideal center of mass sideslip angle can be obtained as:

[0111] Using PID module to track the ideal yaw rate Get the additional yaw moment , tracking the ideal center of mass sideslip angle Get the additional yaw moment The vehicle stability is affected by both the yaw rate and the sideslip angle of the center of mass, so a comprehensive module is set up, and its output is:

[0112] Calculated Corresponding braking force , then The vertical load of each wheel is distributed to the four wheels in proportion to each other, as follows:

[0113]

[0114] Where, are the additional braking forces of the left front wheel, right front wheel, left rear wheel, and right rear wheel respectively. The braking force correction of each wheel is equal to the initial braking force plus its corresponding additional braking force.

[0115] In this embodiment, after determining the braking force distribution method for the front and rear axles of the vehicle, it is necessary to further determine the braking force distribution method between the two coaxial reduction hub motors. Therefore, the above braking strategy also includes: When the vehicle is in a straight-line braking scenario, the braking torques of the two coaxial reduction hub motors are equal and are half of the braking torque on the corresponding shaft; When the vehicle is in a curve braking scenario, the braking torque of each reduction wheel hub motor is obtained according to the above-mentioned initial braking force and additional braking force of the curve.

[0116] It is understandable that in a straight-line braking scenario, the braking force on the front and rear axles is first determined based on the front and rear axle braking force distribution coefficients, and then the distributed braking force is distributed equally between the two coaxial reduction hub motors. As for the method of deriving the braking force of each reduction hub motor in a cornering braking scenario, please refer to the relevant formulas above and will not be repeated here. Therefore, through this braking strategy, the braking force distribution of the reduction hub motors on each wheel of the vehicle can be determined.

[0117] In this embodiment, after determining the braking force distribution of the reduction hub motors on each wheel of the vehicle, it is necessary to further determine the distribution method of the electric braking force and the mechanical braking force on the same reduction hub motor. Therefore, the above braking strategy also includes: When the reduction wheel hub motor brakes using electromechanical composite braking, the electric braking force and mechanical braking force of the reduction wheel hub motor are distributed according to the regenerative braking participation ratio; wherein the regenerative braking participation ratio is obtained according to the fuzzy control rule.

[0118] Specifically, this embodiment provides a fuzzy control rule to achieve the desired regenerative braking force and ensure maximum energy recovery under the premise of safety. As well as the battery SOC as the input variable and the regenerative braking participation ratio N as the output variable, the fuzzy inference rules are determined as shown in the following table:

[0119] The domain is [-1, 1], and the membership functions are triangular and trapezoidal functions. The Mamdani method in the form of IF-THEN rules is used for fuzzy reasoning, and the centroid method is used for defuzzification to obtain the regenerative braking participation ratio N.

[0120] After obtaining the above regenerative braking participation ratio N, the method for determining the distribution method of electric braking force and mechanical braking force is as follows: For the reduction hub motor on the front axle of the vehicle, the distribution is as follows: F mbf =N*F bf , F hbf = (1-N) * F bf ; Among them, F mbf is the electric braking force, F hbf is the mechanical braking force, F bf Braking force for the front axle.

[0121] For the reduction hub motor on the rear axle of the vehicle, the distribution is as follows: F mbr =N*F br , F hbr = (1-N) * F br ; Among them, F mbr is the electric braking force, F hbr is the mechanical braking force, F br Rear axle braking force.

[0122] It can be understood that the above-mentioned method of distributing the electric braking force and the mechanical braking force on the same reduction-type hub motor is applicable to both straight-line braking scenarios and cornering braking scenarios.

[0123] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0124] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0125] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A reduction wheel hub motor, characterized in that: include: An inner rotor motor, comprising a motor housing, a stator, a rotor, a rotor support, and a motor output shaft, wherein the rotor is fixed to the rotor support, and the rotor support is fixedly connected to the motor output shaft; a concave chamber formed between the rotor support and the motor output shaft; and The reducer is embedded in the concave chamber and is used to connect the motor output shaft and the wheel.

2. The reduction hub motor according to claim 1, characterized in that: The motor further comprises a brake, which is mounted on an end of the motor output shaft away from the reducer, and comprises: brake housing; a brake output shaft, disposed on the brake housing and configured to output a braking torque; and a friction brake assembly, disposed inside the brake housing and connected to the brake output shaft, for generating a braking torque and acting on the brake output shaft; Wherein, a brake control component is provided at the connection between the brake output shaft and the motor output shaft, for controlling the transmission of the braking torque on the brake.

3. The reduction hub motor according to claim 2, characterized in that: The brake control assembly includes: a first end face gear, slidably disposed on the motor output shaft; a second end face gear fixedly disposed on the brake output shaft and configured to engage with the first end face gear; and The pushing assembly is connected to the first end face gear and is used to drive the first end face gear to approach or move away from the second end face gear.

4. The reduction hub motor according to claim 3, characterized in that: The pushing assembly includes: movable parts; a piston mechanism connected to the movable member and configured to drive the movable member to move along the motor output shaft; and An elastic reset member is provided on the piston mechanism and is connected to the first end face gear, and is used for driving the first end face gear to reset.

5. A braking method for a reduction wheel hub motor, characterized in that: The reduction hub motor according to any one of claims 1 to 4 comprises: Get vehicle information; Judging and determining a braking scenario of the vehicle based on the vehicle information; and Adopting a corresponding braking strategy to brake the reduction wheel hub motor according to the vehicle information and the braking scenario; The braking scenarios include straight-line braking and curve braking; the braking strategies include full electric braking, non-regenerative electric braking, electromechanical composite braking, and mechanical braking.

6. The braking method of the reduction wheel hub motor according to claim 5, characterized in that: The “judging and determining the braking scenario of the vehicle based on the vehicle information” includes: Obtain steering wheel angle and driving path curvature information; When the steering wheel angle and the driving path curvature are respectively greater than corresponding preset values, determining that the braking scenario of the vehicle is cornering braking; and When the steering wheel angle or the driving path curvature is less than or equal to a corresponding preset value, it is determined that the braking scenario of the vehicle is straight-line braking.

7. The braking method of the reduction hub motor according to claim 5, characterized in that: The “adopting a corresponding braking strategy to brake the reduction-type in-wheel motor according to the vehicle information and the braking scenario” includes: Obtain vehicle brake pedal opening, battery SOC, vehicle speed, and vehicle braking deceleration information; When the vehicle brake pedal opening is less than or equal to a corresponding preset value, the reduction wheel hub motor is braked by a full electric braking method; When the vehicle brake pedal opening is greater than a corresponding preset value, the battery SOC is greater than or equal to a corresponding preset value, and the vehicle speed and the vehicle braking deceleration do not exceed corresponding preset values, braking the reduction-type in-wheel motor using non-regenerative electric braking; and When the vehicle brake pedal opening is greater than the corresponding preset value, the battery SOC is less than the corresponding preset value, and the vehicle speed and the vehicle braking deceleration are both greater than the corresponding preset values, electromechanical composite braking or mechanical braking is used to brake the reduction hub motor.

8. The braking method of the reduction wheel hub motor according to claim 7, characterized in that: The “adopting a corresponding braking strategy to brake the reduction-type in-wheel motor according to the vehicle information and the braking scenario” also includes: When the vehicle meets the conditions for electromechanical composite braking or mechanical braking, obtain vehicle braking intensity information; When the braking intensity is less than or equal to a first threshold, mechanical braking is used to brake the reduction hub motor; When the braking intensity is greater than a first threshold value and less than a second threshold value, the reduction-type hub motor is braked by electromechanical composite braking; and When the braking intensity is greater than or equal to a second threshold, mechanical braking is used to brake the reduction hub motor.

9. The braking method of a reduction wheel hub motor according to claim 7, characterized in that: The “adopting a corresponding braking strategy to brake the reduction-type in-wheel motor according to the vehicle information and the braking scenario” also includes: Determine the vehicle's current braking scenario; and According to the current braking scenario of the vehicle, the corresponding front and rear axle braking force distribution strategy is adopted to distribute the braking force of each of the reduction-type hub motors on the front and rear axles of the vehicle; The front and rear axle braking force distribution strategy includes a straight-line braking distribution mode and a cornering braking distribution mode.

10. The braking method of a reduction wheel hub motor according to any one of claims 5 to 9, characterized in that: When the reduction wheel hub motor is braked in the form of electromechanical composite braking, the electric braking force and mechanical braking force of the reduction wheel hub motor are distributed according to the regenerative braking participation ratio; The regenerative braking participation ratio is obtained according to fuzzy control rules.

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