Integrated wheel end speed reduction electric wheel system and control method

Abstract

The invention relates to an integrated wheel end speed reduction electric wheel system and a control method, and belongs to the technical field of electromechanical coupling structures and control of distributed driving carriers. The speed reducer is embedded in the groove of the motor shell and is positioned in the groove space of the electronic rotor bracket; the speed reducer comprises a planetary gear carrier, and the planetary gear carrier is rotatably connected with a shell of the motor through a rolling bearing; an output shaft of the motor penetrates through a suspension base hole to be fixedly connected with a brake disc of the brake. The braking heat is prevented from being transmitted to the motor body, and the braking control mode is mainly electric braking and is assisted by mechanical braking. The contradiction between high integration and heat dissipation of a hub motor in the prior art is solved, and the space of an electric wheel assembly is optimized to the maximum extent.

Description

Technical Field

[0001] The present invention relates to the field of electromechanical coupling structure and control technology of distributed drive vehicles, and in particular to an integrated wheel-end reduction electric wheel system and a control method. Background Art

[0002] Compared with traditional drive solutions, distributed hub motor drive technology improves space utilization in vehicle structure layout, and shows significant advantages in improving the driving and braking control performance of new energy vehicles, representing the development direction of the automotive industry. At present, hub motors are mainly divided into two types: direct drive and reduction. Direct drive hub motors are difficult to provide sufficient torque under the condition of limited volume and weight. In comparison, the reduction hub motor effectively reduces the motor load through the built-in reducer, while providing the car with a more stable and powerful torque output. At present, most reduction hub motors use planetary gear reducers and are equipped with disc brakes to achieve more efficient power transmission. Without being limited by the installation space, some advanced reduction hub motors use a two-stage planetary gear reducer and realize two-speed shifting through the shifting mechanism, further improving the power performance.

[0003] However, the reduction wheel hub motor still faces some technical challenges in practical application. The existing inner rotor wheel hub motor is difficult to install due to the underutilization of internal space and large axial size, and the internal space has great development potential. The wheel hub motor with highly integrated motor body, reducer and brake has poor heat dissipation performance due to the small internal gap. Heat accumulation will affect the performance and life of the wheel hub motor, and it is easy to cause brake thermal decay and motor demagnetization, making it difficult to ensure safety and reliability. Since the wheel hub motor is often in high-speed operation, if the design is improper, it will lead to poor coupling performance between components, causing problems such as loud noise and poor sealing. In severe cases, it will cause damage to the motor. Summary of the invention

[0004] In view of this, it is necessary to provide an integrated wheel-end reduction electric wheel system and control method to solve the technical problem of poor heat dissipation performance of highly integrated hub motors in the prior art due to small internal space.

[0005] In order to solve the above problems, the present invention provides an integrated wheel-end reduction electric wheel system, including a motor, a reducer and a brake, including: The motor comprises a motor rotor, and the reducer is embedded in the groove of the motor housing and is located in the groove space of the electronic rotor bracket; The reducer comprises a planetary gear carrier, and the planetary gear carrier is rotatably connected to the housing of the motor via a rolling bearing; The output shaft of the motor passes through the suspension base hole and is fixedly connected to the brake disc of the brake.

[0006] In a possible implementation, the planetary gear carrier is connected to a support bearing embedded in a housing of the motor.

[0007] In a possible implementation, it further includes an output shaft bearing, and the output shaft bearing is sleeved on the output shaft.

[0008] In a possible implementation, it also includes an oil seal assembly, which includes a first oil seal, a second oil seal, a third oil seal and a fourth oil seal, the first oil seal is arranged between the planetary gear carrier and the housing of the motor, the second oil seal is arranged between the planetary gear shaft and the gear ring fixing bracket, the third oil seal is arranged on the side of the output shaft and the planetary gear shaft close to the motor rotor, and the fourth oil seal is arranged between the output shaft and the housing of the motor.

[0009] In a possible implementation, the motor is an inner rotor eccentric motor.

[0010] In a possible implementation, the motor further includes a rotor support bearing, and the rotor support bearing is installed on an inner wall of the motor housing.

[0011] In a second aspect, the present invention further provides a control method for an integrated wheel-end reduction electric wheel system, which is applied to any of the above-mentioned integrated wheel-end reduction electric wheel systems, comprising: Obtain brake pedal displacement, brake pedal speed and vehicle speed; According to the brake pedal displacement, brake pedal speed and vehicle speed, the fuzzy control rules are established using the preset fuzzy logic toolbox to obtain the driver's braking intention; The braking torque is distributed according to the vehicle's braking force requirements, the front and rear wheel braking force ratio and the driver's braking intention.

[0012] In a possible implementation, the method of establishing a fuzzy control rule based on the brake pedal displacement, the brake pedal speed and the vehicle speed using a preset fuzzy logic toolbox to obtain the driver's braking intention includes: Perform interval processing on the brake pedal displacement and construct the brake pedal displacement fuzzy subset; Perform interval processing on the brake pedal speed and construct a fuzzy subset of the brake pedal speed; Perform interval processing on vehicle speed and construct fuzzy subset of vehicle speed; According to the fuzzy subsets of brake pedal displacement, brake pedal velocity and vehicle speed, the fuzzy control rules are established using the preset fuzzy logic toolbox to obtain the driver's braking intention.

[0013] In a possible implementation, the distributing the braking torque according to the front and rear wheel braking force ratio includes: According to the influence of the ground's normal reaction force and braking force on the front and rear wheels of the vehicle, the moment of the wheel's contact point is analyzed to determine the correlation between the ground's normal reaction force and the braking force; Based on the correlation between the ground normal reaction force and the braking force, the front and rear wheel braking force distribution ratio under different adhesion coefficient road conditions is determined.

[0014] In a possible implementation, the distributing of the braking torque according to the vehicle braking force requirement, the front and rear wheel braking force ratio and the driver's braking intention includes: According to the driver's braking intention and the ratio of the front and rear wheel braking forces, the relationship between the vehicle's braking force demand and the braking force threshold is compared to determine the vehicle's braking force distribution.

[0015] The beneficial effects of the present invention are: by embedding the reducer in the motor and locating it in the bracket space of the electronic rotor, the reducer and the motor are highly integrated, the axial size of the motor is minimized and the weight of the motor is reduced to the greatest extent, so that the space utilization and power density of the hub motor are greatly improved, the free space is increased, and the heat dissipation efficiency is improved. In addition, the output shaft of the reducer passes through the suspension base and is fixedly connected to the brake disc of the brake, thereby avoiding the problem of heat transfer to the motor during braking and improving the space utilization of the electric wheel assembly.

[0016] Furthermore, the driver's intention is analyzed through fuzzy logic, and electric braking is used first. When the demand exceeds the electric braking capacity, mechanical hydraulic braking is used to supplement it. The front and rear axle braking forces are distributed according to the ideal braking force distribution curve, ensuring the efficiency and stability of braking. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The internal plan view of the motor in the integrated wheel-end reduction electric wheel system provided by the present invention; Figure 2 A schematic diagram of the interior of the motor and the brake in the integrated wheel-end reduction electric wheel system provided by the present invention; Figure 3 A schematic diagram of the appearance of an electric wheel in the integrated wheel-end reduction electric wheel system provided by the present invention; Figure 4 A schematic diagram of the position of the suspension base in the integrated wheel-end reduction electric wheel system provided by the present invention; Figure 5 A schematic flow chart of an embodiment of a control method for an integrated wheel-end reduction electric wheel system provided by the present invention; Figure 6In the control method of the integrated wheel-end reduction electric wheel system provided by the present invention, the vehicle braking force diagram; Figure 7 An ideal braking force distribution curve diagram in the control method of the integrated wheel-end reduction electric wheel system provided by the present invention; in, Figure 1 In the figure: 1 is the wheel hub, 2 is the motor housing, 3 is the motor stator and winding, 4 is the motor rotor bracket, 5 is the planetary gear carrier support bearing, 6 is the first oil seal, 7 is the planetary gear, 8 is the planetary gear bracket, 9 is the first fixing bolt, 10 is the second oil seal, 11 is the planetary gear shaft, 12 is the sun gear, 13 is the third oil seal, 14 is the second fixing bolt, 15 is the suspension assembly, 16 is the large ring gear fixing bracket, 17 is the rotor bracket support bearing, 18 is the third fixing bolt, 19 is the brake disc, 20 is the first output shaft bearing, 21 is the second output bearing, 22 is the output shaft, 27 is the NGW mechanism large ring gear, 28 is the fourth oil seal, and 29 is the motor rotor; Figure 2 In the middle: 2 is the motor housing, 3 is the motor stator and winding, 19 is the brake disc, 20 is the first output shaft bearing, 21 is the second output bearing, 22 is the output shaft, and 23 is the brake caliper; Figure 3 In the middle: 1 is a wheel hub, 19 is a brake disc, 23 is a brake caliper, 24 is an elastic damping element, 25 is a part of a three-phase line, and 26 is a part of a suspension base; Figure 4 Middle: 19 is a brake disc, 23 is a brake caliper, and 26 is a part of a suspension base. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0019] A specific embodiment of the present invention discloses an integrated wheel-end reduction electric wheel system, including a motor, a reducer and a brake, see Figure 1-Figure 4 ,include: The motor comprises a motor rotor, and the reducer is embedded in the groove of the motor housing and is located in the groove space of the electronic rotor bracket; The reducer comprises a planetary gear carrier, and the planetary gear carrier is rotatably connected to the housing of the motor via a rolling bearing; The output shaft of the motor passes through the suspension base hole and is fixedly connected to the brake disc of the brake.

[0020] In this embodiment, the reducer is built into the motor and located in the bracket space of the electronic rotor, and the reducer and the motor are highly integrated, which minimizes the axial size of the motor and reduces the weight of the motor, greatly improving the space utilization and power density of the hub motor, increasing the free space, and improving the heat dissipation efficiency. In addition, the output shaft of the reducer passes through the suspension base and is fixedly connected to the brake disc of the brake, thereby avoiding the problem of heat transfer to the motor during braking and improving the space utilization of the electric wheel assembly.

[0021] In a specific embodiment, the drive transmission integrated electric wheel assembly consists of three parts: a permanent magnet synchronous inner rotor motor, a single-stage NGW type planetary gear reduction system, and a disc brake system. Figure 1 , as shown in 2. Figure 1 Among them, 1 is a wheel hub, 2 is a motor housing, 3 is a motor stator winding, 4 is a motor rotor, 5 is a planetary gear carrier support bearing, 6 is a first oil seal, 7 is a planetary gear, 8 is a planetary gear bracket, 9 is a first fixing bolt, 10 is a second oil seal, 11 is a planetary gear shaft, 12 is a sun gear, 13 is a third oil seal, 14 is a second fixing bolt, 15 is a suspension assembly, 16 is a large ring gear fixing bracket, 17 is a rotor bracket support bearing, 18 is a third fixing bolt, 19 is a brake disc, 20 is a first output shaft bearing, 21 is a second output bearing, and 22 is an output shaft.

[0022] In order to greatly reduce the axial size and reasonably utilize the internal space of the rotor bracket 4, the reducer is embedded in the motor body, and the structure of the traditional reducer is abandoned. The planetary gear carrier 8 and the motor housing 2 are deeply integrated, and the support bearing 5 embedded in the motor housing is used as the support point of the planetary carrier 8. Oil seals are used to ensure the relative independence and sealing between the various parts.

[0023] In order to prevent the adverse effects caused by the high integration of brakes and increase the freedom of suspension layout, such as Figure 2 and 4 As shown, in this embodiment, the output shaft 22 is used as the direct braking torque application point of the brake. Different from the traditional output shaft, the output shaft of this embodiment passes through the suspension base 26 to connect the brake disc 19 and is supported by a pair of output shaft bearings 20 and 21, thereby avoiding the problem of heat transfer to the motor during braking and improving the space utilization of the electric wheel assembly.

[0024] In some embodiments, an output shaft bearing is further included, and the output shaft bearing is sleeved on the output shaft.

[0025] In this embodiment, the brake system (structure) is mainly divided into a brake disc 19 and a brake caliper 23. Figure 4As can be seen from the schematic diagram of the suspension base position, the suspension base 26 is fixed to the motor housing 2 by bolts, which increases the difficulty of brake arrangement. In order to solve this problem while ensuring the safety and reliability of braking, Figure 2 As shown, the output shaft 22 of the present invention passes through the suspension base 26 and is connected to the brake disc 19 by bolts, and then a pair of bearings, namely the first output shaft bearing 20 and the second output shaft bearing 21, are used as supports for the output shaft 22. When the driver steps on the brake pedal, the brake caliper 23 receives the brake signal and clamps the brake disc 19, at which time a braking torque is formed to generate a braking force, which directly acts on the output shaft 22 and finally acts on the wheel hub through the speed reduction mechanism.

[0026] In some embodiments, an oil seal assembly is also included, and the oil seal assembly includes a first oil seal, a second oil seal, a third oil seal and a fourth oil seal, the first oil seal is arranged between the planetary gear carrier and the housing of the motor, the second oil seal is arranged between the planetary gear shaft and the fixed, the third oil seal is arranged on the side of the output shaft and the planetary gear shaft close to the motor rotor, and the fourth oil seal is arranged between the output shaft and the housing of the motor.

[0027] In this embodiment, the reduction mechanism (structure) uses a pair of large bearings, namely the planetary carrier support bearings 5, as support for the power output of the planetary carrier 8, and the planetary carrier support bearings 5 ​​are located between the motor housing 2 and the planetary carrier 8. Secondly, the large ring gear 27 and the motor housing 2 are connected by bolts to ensure that the motor and the reducer are highly integrated. A floating support is used between the sun gear 12 and the output shaft 22, and a floating support is used between the large ring gear 27 and the ring gear fixing bracket 16, which can effectively reduce gear noise. In order to ensure the sealing of the reducer with the outside world, a first oil seal 6 is designed between the planetary carrier 8 (rotating moving part) and the motor housing 2 (stationary part). At the same time, a second oil seal 10 is added between the ring gear fixing bracket 16 and the planetary gear shaft 11 close to the motor rotor, and a third oil seal 13 is added between the output shaft 22 and the planetary gear shaft 11 close to the motor rotor, so as to increase the sealing of the reducer and the inside of the motor.

[0028] The characteristic of the speed reduction mechanism (structure) is that the relative positions of the sun gear 12, the planetary gear 7, the planetary carrier 8 and the support bearing 5 are reasonably arranged, such as Figure 1 As shown, the axial dimension is greatly compressed (73mm), which not only solves the problem of low space utilization of the motor assembly caused by the large size of the reducer, but also reduces the overall weight by reducing the size of the reducer, solving the problem of excessive unsprung mass caused by the electric wheel. In addition, in order to reduce weight, this embodiment also performs topological optimization on the reducer housing and adopts lightweight aluminum alloy materials to minimize the weight of the housing. The main power transmission path of the reducer is sun gear 12→planetary gear 7→planetary gear shaft 11→planet carrier 8→first fixing bolt→wheel hub 1.

[0029] In some embodiments, the motor further comprises a rotor support bearing, wherein the rotor support bearing is mounted on an inner wall of the motor housing.

[0030] In this embodiment, the motor is composed of a stator and winding 3, a rotor 29, an output shaft 22, a housing 2, etc. The motor is designed to be an inner rotor type. Compared with an outer rotor hub motor, it can better follow the torque request of the vehicle under extreme working conditions, making the motor have better overall performance. The motor (structure) schematic diagram can be referred to Figure 1 In order to highly integrate the motor body and the reducer, the design of the rotor 4 is eccentric. At the same time, in order to ensure the reliability of the rotor's power transmission, a rotor bracket support bearing 17 is added between the rotor bracket 4 and the inner wall of the motor housing 2, and the rotor bracket 4 is connected to the output shaft by bolts. In order to ensure the sealing of the motor, in addition to the first oil seal 6, the second oil seal 10, and the third oil seal 13 designed above, a fourth oil seal 28 is also added between the output shaft 22 and the motor housing 2 to prevent foreign matter from entering the motor and causing damage to the motor. The main path of the electric wheel drive power transmission is the motor rotor 4→output shaft 22→sun gear 12→planetary gear 7→planetary gear shaft 11→planetary gear bracket 8→first fixing bolt 9→wheel hub 1.

[0031] Based on the above-mentioned integrated wheel-end reduction electric wheel system, the embodiment of the present invention further provides a control method for the integrated wheel-end reduction electric wheel system, see Figure 5 ,include: S501, obtaining brake pedal displacement, brake pedal speed and vehicle speed; S502, establishing fuzzy control rules using a preset fuzzy logic toolbox according to brake pedal displacement, brake pedal speed and vehicle speed to obtain the driver's braking intention; S503: Distribute the braking torque according to the vehicle braking force requirement, the front and rear wheel braking force ratio, and the driver's braking intention.

[0032] In this embodiment, by combining the advantages of electric braking force and hydraulic braking force, efficient and safe braking control is achieved, especially the optimization of braking performance under different working conditions. Through real signal input and reasonable control rules, the strategy can reflect the driver's braking intention in real time, thereby achieving accurate braking force distribution and improving the stability and safety of the vehicle.

[0033] It should be noted that, in the present embodiment, electric braking, ie, regenerative braking, is mainly used, and mechanical hydraulic braking is supplemented.

[0034] In some embodiments, the method of establishing a fuzzy control rule using a preset fuzzy logic toolbox according to the brake pedal displacement, the brake pedal speed and the vehicle speed to obtain the driver's braking intention includes: Perform interval processing on the brake pedal displacement and construct the brake pedal displacement fuzzy subset; Perform interval processing on the brake pedal speed and construct a fuzzy subset of the brake pedal speed; Perform interval processing on vehicle speed and construct fuzzy subset of vehicle speed; According to the fuzzy subsets of brake pedal displacement, brake pedal velocity and vehicle speed, the fuzzy control rules are established using the preset fuzzy logic toolbox to obtain the driver's braking intention.

[0035] In this embodiment, the analysis of the driver's braking intention involves a certain degree of subjectivity, and the key lies in correctly selecting the coefficient with the largest influence weight. In this embodiment, the brake pedal displacement, brake pedal speed and vehicle speed are selected as identification parameters as large weight coefficients, and fuzzy control rules are established to analyze the driver's braking intention, and four types of driver's braking intentions are obtained. In this embodiment, the "Fuzzy Logic Toolbox" provided by Matlab is used to establish relevant control rules. Among them, the domain of the brake pedal opening signal as input is [0,100], corresponding to 0%~100% pedal displacement, and the fuzzy subset is [Small, Big]. The domain of the brake pedal speed is [0,500], corresponding to 0% / s~500% / s brake pedal speed, the fuzzy subset is [Zero Slow Quick], and the domain of the input vehicle speed is [0 200], corresponding to 0Kph to 200Kph vehicle speed, and the fuzzy subset is [Slow High]. The fuzzy controller outputs the driver's target braking intention, which is divided into four categories: emergency braking, regulating braking, continuous braking, and parking braking. Its domain is 0~3, corresponding to the four expected braking methods of continuous braking, regulating braking, parking braking, and emergency braking. The established fuzzy rules are shown in Table 1 below: Table 1: Fuzzy rules diagram

[0036] After setting the membership function and fuzzy rules, the fuzzy controller can analyze the driver's braking intention according to the different input brake pedal openings and brake pedal speeds, and accurately classify it, and output any integer from 0 to 3 to represent the driver's intention.

[0037] In some embodiments, the distributing the braking torque according to the front and rear wheel braking force ratio includes: According to the influence of the ground's normal reaction force and braking force on the front and rear wheels of the vehicle, the moment of the wheel's contact point is analyzed to determine the correlation between the ground's normal reaction force and the braking force; Based on the correlation between the ground normal reaction force and the braking force, the front and rear wheel braking force distribution ratio under different adhesion coefficient road conditions is determined.

[0038] In this embodiment, when the vehicle is in a braking condition, if the front and rear wheels are locked at the same time, it is an ideal condition. Therefore, before designing the front and rear axle braking force distribution strategy, it is necessary to understand the reaction force of the ground acting on the vehicle under the braking condition. The force of the vehicle when braking on a horizontal road is as follows: Figure 6 shown.

[0039] Figure 6 middle, , Respectively represent the normal reaction force of the ground on the front and rear wheels; , Respectively represent the braking force of the front and rear wheels; is the vehicle inertia force; is the height of the vehicle's center of mass; is the wheelbase, ; , Respectively represent the distance from the vehicle's center of mass to the front and rear axles; is the vehicle gravity.

[0040] Taking the moment at the wheel contact point, the ground normal reaction force is: (1) In the formula, For the braking strength.

[0041] When braking on roads with different adhesion coefficients, when both the front and rear wheels are locked, we can get: (2) (3) (4) When the sum of the braking forces of the front and rear wheel brakes of the vehicle is equal to the adhesion, and the braking forces of the front and rear wheel brakes are equal to their respective adhesions, the front and rear wheels are locked at the same time, that is: (5) In the formula, , is the front and rear wheel braking force, substitute equation (4) into the above equation and substitute the variables , we can get: (6) Plotting equation (6) into a curve gives the ideal braking force distribution curve, as shown in Figure 7During vehicle braking, the braking force ratio of the front and rear wheels should be below the ideal braking force curve, and the closer to the ideal braking force distribution curve, the better, to avoid the dangerous condition of the rear wheels locking first.

[0042] In some embodiments, the distributing of the braking torque according to the vehicle braking force demand, the front and rear wheel braking force ratio and the driver's braking intention includes: According to the driver's braking intention and the ratio of the front and rear wheel braking forces, the relationship between the vehicle's braking force demand and the braking force threshold is compared to determine the vehicle's braking force distribution.

[0043] In this embodiment, when the vehicle requires a small braking force, for example When the vehicle is under high braking intensity, for example , based on the ideal braking force curve, the front and rear wheel braking forces of the vehicle are distributed. The electric braking capacity is first exerted. When the braking torque required by the vehicle is greater than the electric braking torque, the hydraulic braking force will make up for it. The vehicle is equipped with an IBC system, and the hydraulic braking force of each brake wheel cylinder can be independently adjusted according to the total braking force required by the vehicle and the electric braking force.

[0044] When the battery SOC is too high, the ABS is working, or the wheel hub motor system fails, regenerative braking will be exited and mechanical braking will be activated. According to power calculation and battery motor constraints, when the electric braking capacity cannot meet the vehicle's braking capacity, the mechanical brake fluid pressure will be used to make up for the missing torque. The constraints are: (2) In the formula is the motor regenerative braking current; is the maximum charging current of the power battery, is the motor regenerative braking power, It is the maximum charging power of the power battery.

[0045] In the braking process of the embodiment of the present invention, the total braking torque required by the vehicle is linearly related to the brake pedal opening. The relationship between the four-wheel braking force and the total braking torque required by the vehicle is: (7) In the formula, is the total braking torque required by the vehicle; is the wheel radius, , Respectively represent the braking force of the left front wheel and the right front wheel; , Represents the braking force of the left rear wheel and the right rear wheel respectively.

[0046] The front and rear wheel braking force distribution strategy is based on the ideal braking force curve. This distribution method can ensure that the vehicle has good braking stability during braking and can maximize the use of electric motor force. The relationship between the front and rear wheel braking forces is: (8) The wheel coaxial wheel braking force meets: (9) The braking force ratio of the coaxial wheels of a vehicle is: (10) By solving equations (8)-(10) together, the four-wheel braking force of the vehicle can be obtained. After calculating the braking force, the VCU sends a command to the ECU to control the motor controller to perform electric braking. When the electric braking is not enough to meet the braking demand, it sends a command to the IBC device to perform hydraulic braking. During the braking process, ABS monitors the entire process. When a wheel is about to lock or fails, ABS intervenes and all other controls are exited.

[0047] When hydraulic braking force intervention is required, due to the delay of the hydraulic system, the actual deceleration will inevitably fail to track the target value for a period of time. In order to make the hydraulic system quickly rise to the ideal value after the delay, it is necessary to give it a higher command. When the target braking strength signal increases rapidly, the signal input to the hydraulic pressure is the conventional distribution signal. times, keep for a while , and Calibrated by experiment.

[0048] In a specific embodiment, according to the above structure and control strategy, the vehicle starts to brake to a stop at an initial speed of 200 km / h with a braking deceleration of 6.37 m / s2. Under the joint constraints of the motor and battery, the vehicle braking torque is 16999 to 18154 , the wheel-end braking torque can be obtained from the vehicle torque. The braking torque at the wheel reducer input end can be calculated based on the reduction ratio, wheel radius and other coefficients. Under the condition that the electric braking force is fully utilized, the mechanical braking torque that needs to be involved can be known. Fully utilize the electric braking capacity, perform battery constraints according to the battery map and consider the motor constraints. The vehicle braking force and wheel-end braking force gradually decrease with the increase of vehicle speed. The electric braking torque remains constant at a lower speed of 330N·m, but begins to decrease when the vehicle speed exceeds 59.28 km / h, indicating that the electric braking system cannot provide constant braking force at higher speeds. At this time, the mechanical braking system begins to intervene to supplement the required braking force. The remaining mechanical braking torque increases with the increase of vehicle speed, which corresponds to the reduction of the electric braking torque. During high-speed braking, the supplementary effect of the electric braking system decreases, and the mechanical braking system needs to provide more braking force to meet the braking demand.

[0049] Therefore, the embodiment of the present invention highly integrates the reducer with the motor, minimizes the axial size of the motor (73mm) and reduces the weight of the motor to the greatest extent, so that the space utilization and power density of the hub motor are greatly improved. Secondly, based on the torque requirements of the whole vehicle, the unsprung mass and size restrictions, the reducer is embedded in the motor body, and the traditional shape of the reducer is overturned to make it highly flat. At the same time, the reducer housing is topologically optimized, and lightweight aluminum alloy materials are used to greatly reduce the weight of its shell. The brake system is reasonably arranged using the suspension base space to maximize the space utilization and ensure the braking performance of the whole vehicle. The oil seal position is fully calculated, and floating supports are used to break through many key problems such as dust prevention and noise in actual applications, solving the defect that the noise of the reduction type electric wheel is greater than that of the direct drive type. By optimizing the locking nut part structure, increasing the center distance of the planetary gear and reducing the gear system tooth thickness, the axial size of the reducer is effectively reduced, solving the defects of the existing inner rotor electric wheel, such as large volume and difficulty in installation, and large unsprung mass that is not conducive to vehicle handling stability and smoothness. By connecting the brake disc through the output shaft through the suspension base, the space utilization of the electric wheel assembly is further optimized, and the problem of shortened motor life and reduced performance due to heat transfer during braking is eliminated. Based on various operating conditions of passenger vehicles and the requirements for strength, life and reliability of the hub motor body, the dynamic stability of the hub motor assembly drive braking system is deeply studied to improve the torque density and comprehensive performance of the hub motor system. The hub motor control strategy of the present invention integrates advanced braking intention recognition and braking force distribution systems, realizes driver intention analysis through fuzzy logic, gives priority to electric braking, and is supplemented by mechanical hydraulic braking when demand exceeds the electric braking capacity. The front and rear axle braking forces are distributed according to the ideal braking force distribution curve to ensure the efficiency and stability of braking. At the same time, the system takes into account the constraints of the motor and battery, and the ABS system monitors to ensure safety.

[0050] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An integrated wheel-end reduction electric wheel system, comprising a motor, a reducer and a brake, characterized in that: The motor comprises a motor rotor, and the reducer is embedded in the groove of the motor housing and is located in the groove space of the electronic rotor bracket; The reducer comprises a planetary gear carrier, and the planetary gear carrier is rotatably connected to the housing of the motor via a rolling bearing; The output shaft of the motor passes through the suspension base hole and is fixedly connected to the brake disc of the brake.

2. The integrated wheel-end reduction electric wheel system according to claim 1, characterized in that: The planetary gear carrier is connected to a support bearing embedded in a housing of the motor.

3. The integrated wheel-end reduction electric wheel system according to claim 1, characterized in that: It also includes an output shaft bearing, which is sleeved on the output shaft.

4. The integrated wheel-end reduction electric wheel system according to claim 1, characterized in that: It also includes an oil seal assembly, which includes a first oil seal, a second oil seal, a third oil seal and a fourth oil seal, the first oil seal is arranged between the planetary gear carrier and the housing of the motor, the second oil seal is arranged between the planetary gear shaft and the gear ring fixing bracket, the third oil seal is arranged on the side of the output shaft and the planetary gear shaft close to the motor rotor, and the fourth oil seal is arranged between the output shaft and the housing of the motor.

5. The integrated wheel-end reduction electric wheel system according to claim 1, characterized in that: The motor is an inner rotor eccentric motor.

6. The integrated wheel-end reduction electric wheel system according to claim 1, characterized in that: The motor further comprises a rotor support bearing, wherein the rotor support bearing is mounted on an inner wall of the motor housing.

7. A control method for an integrated wheel-end reduction electric wheel system, applied to the integrated wheel-end reduction electric wheel system as claimed in any one of claims, characterized in that: include: Obtain brake pedal displacement, brake pedal speed and vehicle speed; According to the brake pedal displacement, brake pedal speed and vehicle speed, the fuzzy control rules are established using the preset fuzzy logic toolbox to obtain the driver's braking intention; The braking torque is distributed according to the vehicle's braking force requirements, the front and rear wheel braking force ratio and the driver's braking intention.

8. The control method of the integrated wheel-end reduction electric wheel system according to claim 7, characterized in that: The method of establishing a fuzzy control rule based on the brake pedal displacement, brake pedal speed and vehicle speed using a preset fuzzy logic toolbox to obtain the driver's braking intention includes: Perform interval processing on the brake pedal displacement and construct the brake pedal displacement fuzzy subset; Perform interval processing on the brake pedal speed and construct a fuzzy subset of the brake pedal speed; Perform interval processing on vehicle speed and construct fuzzy subset of vehicle speed; According to the fuzzy subsets of brake pedal displacement, brake pedal velocity and vehicle speed, the fuzzy control rules are established using the preset fuzzy logic toolbox to obtain the driver's braking intention.

9. The control method of the integrated wheel-end reduction electric wheel system according to claim 7, characterized in that: The distributing of the braking torque according to the front and rear wheel braking force ratio includes: According to the influence of the ground's normal reaction force and braking force on the front and rear wheels of the vehicle, the moment of the wheel's contact point is analyzed to determine the correlation between the ground's normal reaction force and the braking force; Based on the correlation between the ground normal reaction force and the braking force, the front and rear wheel braking force distribution ratio under different adhesion coefficient road conditions is determined.

10. The control method of the integrated wheel-end reduction electric wheel system according to claim 7, characterized in that: The distributing of the braking torque according to the vehicle braking force demand, the front and rear wheel braking force ratio and the driver's braking intention includes: According to the driver's braking intention and the ratio of the front and rear wheel braking forces, the relationship between the vehicle's braking force demand and the braking force threshold is compared to determine the vehicle's braking force distribution.

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