Rear-drive vehicle energy recovery control method, system, equipment, medium and product

Abstract

The invention relates to the technical field of automobile control, in particular to a rear-drive vehicle energy recovery control method, system and device, a medium and a product. Comprising the steps that when a vehicle steers and is in a braking state, vehicle driving parameters are collected, and the longitudinal braking force upper limit value when rear wheels of the vehicle on a current driving road keep stable and do not break through the attachment limit is calculated; and under the condition that friction braking of the rear axle of the vehicle is not intervened, if the current rear axle energy recovery braking force exceeds the upper limit value of the longitudinal braking force, the rear axle energy recovery braking force is reduced to not exceed the upper limit value of the longitudinal braking force, and meanwhile, the front axle braking force is increased to keep the total braking force of the vehicle unchanged. According to the energy recovery control method for the rear-drive vehicle, the rear axle energy recovery braking force and the front axle braking force can be accurately controlled and adjusted when the vehicle is in the steering and braking states, it is ensured that drifting is avoided when the risk that the rear axle of the vehicle breaks through the attachment limit condition exists, the vehicle driving safety is guaranteed, and the deceleration of the vehicle is kept unchanged.

Description

Technical Field

[0001] This invention relates to the field of automotive control technology, specifically to a method, system, device, medium, and product for energy recovery control of rear-wheel drive vehicles. Background Technology

[0002] In new energy rear-wheel-drive vehicles, energy recovery is concentrated on the rear axle, including recuperation during coasting. During braking, if the rear axle's energy recovery capacity is sufficient, braking requests will be prioritized for the rear axle energy recovery system. When further friction braking is applied, it is superimposed on regenerative braking, resulting in excessive braking force on the rear axle. Under complex operating conditions where the vehicle demands significant longitudinal and lateral forces, the rear axle is highly susceptible to exceeding its adhesion limit, severely impacting the vehicle's handling stability.

[0003] Currently, there are several technical solutions for distributing and controlling vehicle braking force. For example, there is an existing technology entitled "Vehicle Braking Force Distribution Method, Device, Controller, and Storage Medium," which provides a method for distributing vehicle braking force. This method is applied to the vehicle controller of an electric vehicle, acquiring the braking signal from the vehicle's brake pedal, and obtaining the total braking force of the vehicle based on the braking signal. It determines the critical braking force required for front axle lock-up, the maximum allowable regenerative braking force for the rear axle, and the critical braking force required for rear axle lock-up. If it is determined that the vehicle's current speed is greater than the minimum speed required to trigger regenerative braking, the rear axle braking force is determined based on the total braking force and the I-curve. The I-curve represents the braking force required when the vehicle brakes. To achieve simultaneous locking of the front and rear wheels of a vehicle, the braking forces of the front and rear axles should satisfy a relationship curve, where the I curve is obtained through force analysis calculations of the vehicle during braking. If a tendency for the front wheels to lock is detected, the front axle braking force is set as the critical front axle lock-up requirement braking force. If the rear axle braking force is determined to be greater than the maximum allowable regenerative braking force of the rear axle, the mechanical braking force of the rear axle is set as the difference between the rear axle braking force and the maximum allowable regenerative braking force of the rear axle, and the regenerative braking force of the rear axle is set as the maximum allowable regenerative braking force of the rear axle. If a tendency for the rear wheels to lock is detected, the rear axle braking force is set as the critical rear axle lock-up requirement braking force.

[0004] This method determines the regenerative braking force to be used when the rear wheels are about to lock up by determining that the required braking force for critical rear wheel lock-up is less than the maximum allowable regenerative braking force for the rear axle, and sets the regenerative braking force of the rear axle as the force used when the rear wheels are about to lock up. This method maximizes the utilization of regenerative braking force and achieves optimal braking effect through braking force distribution. However, when this method only considers that the regenerative braking force of the rear wheels is greater than the braking force at the critical lock-up point, it reduces the regenerative braking force of the rear wheels to the critical lock-up braking force, without considering the risk of insufficient lateral adhesion at the critical lock-up point.

[0005] In some extreme situations, the above methods have certain problems. For example, on downhill mountain roads, vehicles face a combination of slope, sharp turns, and deceleration and braking, placing high demands on the longitudinal adhesion of the rear wheels, while sharp turns also require sufficient lateral adhesion. Rear-wheel-drive vehicles are prone to oversteer in such conditions due to insufficient rear axle braking force. Current technology typically disengages rear axle energy recovery immediately after detecting oversteer. This not only causes the driver to notice a significant loss of deceleration, but also prevents the vehicle speed from decreasing as expected, leading to excessively high cornering speeds and posing a significant risk to driving safety. Therefore, an innovative technical solution is urgently needed to optimize the energy recovery and braking distribution strategies of rear-wheel-drive vehicles, ensuring driving safety and stability under complex conditions. Summary of the Invention

[0006] The purpose of this application is to address the shortcomings of the aforementioned background technology and to provide a method, system, device, medium, and product for energy recovery control of rear-wheel drive vehicles.

[0007] The technical solution of this application is: a method for energy recovery control of a rear-wheel drive vehicle, comprising: When the vehicle is turning and braking, the vehicle driving parameters are collected, and the upper limit of longitudinal braking force, rear axle energy recovery braking force and target braking force are calculated when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current driving road. If the current rear axle energy recovery braking force exceeds the longitudinal braking force limit when the rear axle friction braking is not engaged, the rear axle energy recovery braking force is reduced to not exceed the longitudinal braking force limit, while the front axle braking force is increased to keep the total braking force of the front and rear vehicles constant.

[0008] According to the energy recovery control method for a rear-wheel drive vehicle provided in this application, when the current rear axle energy recovery braking force exceeds the upper limit of the longitudinal braking force, the rear axle energy recovery braking force is reduced to be equal to the upper limit of the longitudinal braking force.

[0009] According to the energy recovery control method for a rear-wheel drive vehicle provided in this application, if the upper limit of the longitudinal braking force exceeds the current energy recovery braking force of the rear axle, the front axle braking force is reduced and the rear axle energy recovery braking force is increased, so that the total braking force of the front and rear vehicles remains unchanged.

[0010] According to the energy recovery control method for a rear-wheel drive vehicle provided in this application, when the upper limit of the longitudinal braking force exceeds the current energy recovery braking force of the rear axle, the energy recovery braking force of the rear axle is increased to make it equal to the upper limit of the longitudinal braking force or equal to the target braking force.

[0011] According to the energy recovery control method for a rear-wheel drive vehicle provided in this application, the method for calculating the upper limit of the longitudinal braking force when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current driving road includes: calculating the dynamic load of the rear axle and the lateral force of the rear wheels based on the collected vehicle driving parameters, and calculating the upper limit of the longitudinal braking force according to the following formula: in: F xmax —The upper limit of longitudinal braking force when the rear wheels of a vehicle remain stable and do not exceed the adhesion limit on the current road surface; μ —The road surface adhesion coefficient of the current driving road; F r —Rear axle dynamic load; F y —Rear wheel lateral force.

[0012] According to the energy recovery control method for a rear-wheel drive vehicle provided in this application, the method for calculating the dynamic load on the rear axle of the vehicle based on the collected vehicle driving parameters includes: calculating the dynamic load on the rear axle according to the following formula: in: F r —Rear axle dynamic load; F r0 — Rear axle static load; m —Total vehicle weight; h g —Vehicle center of gravity height; z —Target for vehicle deceleration; θ —The gradient angle of the current road; L — Wheelbase.

[0013] According to the energy recovery control method for a rear-wheel drive vehicle provided in this application, the method for calculating the lateral force of the rear wheels of the vehicle based on the collected vehicle driving parameters includes: calculating the lateral force of the rear wheels of the vehicle based on the steering wheel angle, the rate of change of the steering wheel angle and the vehicle speed in the collected vehicle driving parameters.

[0014] This application also relates to a rear-wheel drive vehicle energy recovery control system, which operates according to the aforementioned rear-wheel drive vehicle energy recovery control method, including... The data acquisition module is used to collect vehicle driving parameters when the vehicle is turning and braking. The limit calculation module is used to calculate the upper limit of longitudinal braking force when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current driving road, based on the vehicle driving parameters. The condition judgment module determines whether the starting conditions are met based on the vehicle's rear axle braking force data, and determines that the starting conditions are not met if the vehicle's rear axle friction braking is not engaged. The first comparison module is used to compare the current rear axle energy recovery braking force with the upper limit value of the longitudinal braking force; The first rear axle adjustment module is used to reduce the rear axle energy recovery braking force so that it does not exceed the upper limit of the longitudinal braking force when the start-up conditions are met and the current rear axle energy recovery braking force exceeds the upper limit of the longitudinal braking force. The first front axle adjustment module is used to increase the front axle braking force when the rear axle energy recovery braking force decreases, so as to keep the total braking force of the vehicle constant.

[0015] According to the energy recovery control system for a rear-wheel drive vehicle provided in this application, the first rear axle adjustment module is used to reduce the energy recovery braking force of the rear axle so that it is equal to the upper limit of the longitudinal braking force.

[0016] According to the energy recovery control system for a rear-wheel drive vehicle provided in this application, it also includes, The second comparison module is used to compare the current rear axle energy recovery braking force with the upper limit of the longitudinal braking force again. The second rear axle adjustment module is used to increase the rear axle energy recovery braking force when the current rear axle energy recovery braking force is lower than the upper limit of the longitudinal braking force. The second front axle adjustment module is used to reduce the front axle braking force when the rear axle energy recovery braking force increases, so as to keep the total braking force of the vehicle constant.

[0017] According to the energy recovery control system for a rear-wheel drive vehicle provided in this application, the second rear axle adjustment module is used to increase the energy recovery braking force of the rear axle so that it is equal to the upper limit of the longitudinal braking force or equal to the target braking force.

[0018] According to the energy recovery control system for a rear-wheel drive vehicle provided in this application, the limit calculation module calculates the dynamic load on the rear axle and the lateral force on the rear wheels based on the collected vehicle driving parameters, and calculates the upper limit of the longitudinal braking force according to the following formula: in: F xmax—The upper limit of longitudinal braking force when the rear wheels of a vehicle remain stable and do not exceed the adhesion limit on the current road surface; μ —The road surface adhesion coefficient of the current driving road; F r —Rear axle dynamic load; F y —Rear wheel lateral force.

[0019] According to the energy recovery control system for a rear-wheel drive vehicle provided in this application, the method by which the limit calculation module calculates the dynamic load on the rear axle of the vehicle based on the collected vehicle driving parameters includes: calculating the dynamic load on the rear axle according to the following formula: in: F r —Rear axle dynamic load; F r0 — Rear axle static load; m —Total vehicle weight; h g —Vehicle center of gravity height; z —Target for vehicle deceleration; θ —The gradient angle of the current road; L — Wheelbase.

[0020] μ —The road surface adhesion coefficient of the current driving road; F y —Rear wheel lateral force.

[0021] This application also relates to an electronic device, including a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the above-described energy recovery control method for a rear-wheel drive vehicle.

[0022] This application also relates to a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the above-described energy recovery control method for a rear-wheel drive vehicle.

[0023] This application also relates to a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the above-described energy recovery control method for a rear-wheel drive vehicle.

[0024] The advantages of this application are as follows: 1. The energy recovery control method for rear-wheel drive vehicles in this application can effectively control the energy recovery braking force of the rear-wheel drive vehicle when the vehicle is in a steering and braking state. When there is a risk of the rear axle exceeding the adhesion limit, the energy recovery braking force of the rear axle can be reduced while the braking force of the front axle is increased simultaneously to maintain the total braking force unchanged, thereby improving the lateral stability of the vehicle, avoiding fishtailing and ensuring vehicle driving safety; the advantages of electromechanical braking are utilized to ensure that the total deceleration remains unchanged during the braking force transfer process, eliminating the driver's sense of jerking; energy recovery is prioritized and friction braking is only activated when necessary to maximize the energy recovery efficiency and improve the overall vehicle range; 2. In the process of reducing the energy recovery braking force of the rear axle, this application always maintains the maximum energy recovery braking force of the rear axle under the current conditions, so as to maximize energy recovery while maintaining vehicle stability, maximize the energy recovery efficiency, and improve the vehicle's range. 3. After the current upper limit of longitudinal braking force is increased, this application immediately increases the energy recovery braking force of the rear axle to ensure timely recovery of braking energy and improve the efficiency and degree of braking energy recovery. 4. After restoring the energy recovery braking force of the rear axle, this application will increase the energy recovery braking force of the rear axle to make it equal to the upper limit of the longitudinal braking force, so as to recover braking energy to the maximum extent and further improve the driving range; 5. The method of this application for calculating the upper limit of longitudinal braking force when the rear wheels of a vehicle remain stable and do not exceed the adhesion limit on the current driving road is very simple. The upper limit of longitudinal braking force is calculated by the dynamic load of the rear axle and the lateral force of the rear wheels. The calculation result is accurate and can truly reflect the limit of rear axle stability. 6. This application calculates the dynamic load of the rear axle based on driving data such as the static load and slope angle of the rear axle. The calculation method is simple and can quickly obtain the load of the rear axle when the vehicle is in motion, which facilitates further calculation of the upper limit of the longitudinal braking force. 7. The method for calculating the rear wheel lateral force in this application is based on the steering wheel angle, the rate of change of the steering wheel angle, and the vehicle speed. By constructing a dynamic model, the collected driving parameters can be imported into the dynamic model to quickly obtain the rear wheel lateral force, which facilitates the subsequent calculation of the upper limit of the longitudinal braking force. 8. This application also relates to a rear-wheel drive vehicle energy recovery control system. The control system of this application integrates the above-mentioned rear-wheel drive vehicle energy recovery control method and can be integrated into the vehicle's control system. When the vehicle is in a steering and braking state, if there is a risk of the rear axle exceeding the adhesion limit, the energy recovery braking force of the rear axle can be reduced, the braking friction of the front axle can be increased, the total braking force can be kept constant, that is, the vehicle deceleration remains constant, the vehicle stability can be maintained, and the vehicle will not be jerked. 9. The first rear axle adjustment module of the control system of this application can reduce the rear axle energy recovery braking force to the minimum while maintaining vehicle stability, ensuring efficient recovery of braking energy and improving the vehicle's driving range. 10. This application also includes a second comparison module, a second rear axle adjustment module, and a second front axle adjustment module, which can promptly increase the energy recovery braking force of the rear axle after the upper limit of the longitudinal braking force is increased, restore the efficient recovery state of the energy recovery feedback module of the rear axle, and improve the range; 11. The second rear axle adjustment module of the control system of this application can maximize the rear axle energy recovery braking force while maintaining vehicle stability, ensuring that braking energy can be recovered to the maximum extent and improving the vehicle's driving range. 12. The limit calculation module of this application calculates the upper limit of longitudinal braking force according to the set calculation method. The calculation method is very simple and can truly reflect the critical state of the rear axle breaking through the adhesion limit, which facilitates the subsequent adjustment of the rear axle braking force. 13. The limit calculation module of this application also includes the calculation of the dynamic load of the rear axle. Its integrated calculation method can quickly calculate the dynamic load of the rear axle. The calculation method is simple and can quickly obtain the load of the rear axle when the vehicle is in motion, which facilitates further calculation of the upper limit of the longitudinal braking force. 14. This application also provides an electronic device that can be integrated into the vehicle control system of an automobile to form a matching software module. It can automatically control the vehicle's braking force without any human intervention, providing a more stable and safer driving experience and maintaining efficient rear axle energy recovery. 15. This application also relates to a non-transitory computer-readable storage medium, which stores a corresponding computer program, so that the vehicle control system can perform corresponding control operations based on the stored computer program, which can greatly improve the stability of the vehicle in the steering and braking states and prevent jerking problems. 16. This application also relates to a program product that can be integrated into the vehicle's control system as a software module to automatically control the rear axle energy recovery braking force and front axle braking during steering and braking, resulting in more stable and safer vehicle driving and eliminating jerking problems.

[0025] The energy recovery control method for rear-wheel drive vehicles proposed in this application can precisely control and adjust the energy recovery braking force of the rear axle and the braking force of the front axle when the vehicle is in a steering or braking state. This ensures that when there is a risk of the rear axle exceeding the adhesion limit, it avoids fishtailing, ensures vehicle driving safety, and maintains vehicle deceleration without any jerking issues. It has great potential for widespread application. Attached Figure Description

[0026] Figure 1 This application includes a schematic diagram of the energy recovery control method for rear-wheel drive vehicles. Figure 2 The curves showing the changes in rear axle energy recovery braking force and front axle braking force over time in this application; Figure 3 : Schematic diagram of the energy recovery control device for a rear-wheel drive vehicle in this application. Detailed Implementation

[0027] The embodiments of this application are described in detail below, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0028] In the description of this application, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They 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, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] This application relates to an energy recovery control method for rear-wheel drive vehicles. This control method is primarily applied to rear-wheel drive vehicles equipped with electromechanical braking. Each of the four wheels of the vehicle is equipped with an electromechanical braking module, and an energy recovery feedback module is mounted on the rear axle. When a braking request is received, the rear axle energy recovery feedback module, as well as the electromechanical braking modules on the front and rear axles, can provide braking force to the vehicle. Because the rear axle energy recovery feedback module itself can generate a relatively large braking force (typically producing a braking deceleration of 0.3g), and because this control method mainly targets braking during vehicle steering, where braking is generally fully covered by the rear axle energy recovery feedback module alone, and the braking force generated by the rear axle energy recovery feedback module can meet the steering braking requirements in most situations, this application mainly discusses the situation where the rear wheel friction braking force is not engaged when the vehicle is steering and a braking request is received; in this case, the rear wheel braking force is provided by the rear axle energy recovery feedback module. In this situation, this application determines whether there is a risk of the rear axle exceeding the adhesion limit (the adhesion limit in this application refers to the limit of the rear wheel slip ratio corresponding to the rear axle when it reaches the current driving state; if the slip ratio continues to increase, the rear wheel will fishtail). If there is such a risk of exceeding the adhesion limit, this application avoids this risk by reducing the rear axle energy recovery braking force provided by the rear axle energy recovery feedback module, thereby improving the vehicle's driving stability in the steering state, avoiding fishtailing, and at the same time increasing the vehicle's front axle braking force to maintain the vehicle's deceleration constant. The vehicle will not experience any jerking, thus improving the driving experience.

[0032] Specifically, such as Figure 1 As shown, the energy recovery control method for a rear-wheel drive vehicle according to this application is carried out according to the following steps: S1. When the vehicle is turning and braking, collect vehicle driving parameters and calculate the upper limit of longitudinal braking force, rear axle energy recovery braking force and target braking force when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current driving road. The vehicle driving parameters that need to be collected include steering wheel angle signal, brake pedal signal, steering wheel angle change rate, vehicle speed, road slope angle and road surface adhesion coefficient. Based on the collected driving parameters, the upper limit of longitudinal braking force can be calculated when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current road. The upper limit of longitudinal braking force reflects the critical rear axle braking force when the rear axle does not exceed the adhesion limit under the current road conditions. If this upper limit of longitudinal braking force is exceeded, the rear wheels of the rear axle may exceed the adhesion limit, i.e., fishtailing. S2. If the current rear axle energy recovery braking force exceeds the longitudinal braking force limit when the rear axle friction braking is not engaged, reduce the rear axle energy recovery braking force to ensure it does not exceed the longitudinal braking force limit. At the same time, increase the front axle braking force to keep the total braking force of the vehicle (total braking force refers to the braking force of the vehicle's current front axle braking force and rear axle braking force superimposed, which is actually the target braking force. Before adjusting the rear axle energy recovery braking force, the target braking force is entirely provided by the rear axle energy recovery feedback module, that is, the rear axle energy recovery braking force is equal to the target braking force. After adjusting the rear axle energy recovery braking force, the target braking force is equal to the sum of the rear axle energy recovery braking force and the front axle braking force) unchanged. Because the rear axle energy recovery module provides braking force to the vehicle at this time, and the rear axle electromechanical braking module does not intervene, when the rear axle energy recovery braking force exceeds the upper limit of the longitudinal braking force, the rear wheels of the rear axle are at risk of exceeding the adhesion limit, and the rear axle braking force needs to be adjusted in time. This application eliminates this risk by reducing the rear axle energy recovery braking force so that it does not exceed the upper limit of the longitudinal braking force. At the same time, in order to avoid the jerking problem caused by the reduction of vehicle deceleration due to the reduction of rear axle energy recovery braking force, this application increases the front axle braking force while reducing the rear axle energy recovery braking force. The increase in front axle braking force is exactly the same as the reduction in rear axle energy recovery braking force, so the total braking force of the entire vehicle remains unchanged, the vehicle deceleration does not change, and naturally the vehicle will not experience jerking, and the vehicle rides very smoothly.

[0033] Because the adjustment of the front axle braking force in this application is accomplished by the electromechanical braking module of the front axle, the electromechanical braking module controller has a millisecond-level response, and the electromechanical braking module has the advantages of no hydraulic delay and independent generation of clamping force for the front and rear wheels, which can ensure the smoothness of braking force transfer.

[0034] The energy recovery control method for rear-wheel drive vehicles disclosed in this application can reduce the energy recovery braking force of the rear axle and simultaneously increase the braking force of the front axle when there is a risk of the rear axle exceeding the adhesion limit. This maintains the total braking force unchanged, improves the lateral stability of the vehicle, avoids fishtailing, and ensures vehicle driving safety. It utilizes the advantages of electromechanical braking to keep the total deceleration constant during the braking force transfer process, eliminating the driver's sense of jerkiness. It prioritizes energy recovery and only activates friction braking when necessary, maximizing the energy recovery efficiency and improving the vehicle's range.

[0035] In some embodiments of this application, the above-described energy recovery control method for rear-wheel drive vehicles has been further optimized, specifically, step S3 is also included.

[0036] S3. If the upper limit of longitudinal braking force exceeds the current energy recovery braking force of the rear axle (for example, after the steering wheel angle is reduced), then the front axle braking force is reduced and the energy recovery braking force of the rear axle is increased, so that the total braking force of the vehicle remains unchanged.

[0037] After reducing the rear axle energy recovery braking force, the upper limit of the longitudinal braking force increases. This increased upper limit exceeds the current rear axle energy recovery braking force. Therefore, to maximize energy recovery, the rear axle energy recovery braking force needs to be increased. Simultaneously, to maintain a constant vehicle deceleration, the previously increased front axle braking force needs to be reduced. The reduction in front axle braking force is roughly equivalent to the increase in rear axle energy recovery braking force, maintaining a constant total braking force and eliminating the jerking issue.

[0038] When the vehicle's driving state changes, the corresponding vehicle braking situation also changes, the upper limit of longitudinal braking force changes, and the corresponding limit of rear axle energy recovery braking force also changes. In order to maximize energy recovery, the rear axle energy recovery braking force needs to be increased. The increase in rear axle energy recovery braking force is equal to the decrease in front axle braking force, so the total braking force remains unchanged.

[0039] In a further embodiment of this application, steps S2 and S3 described above are optimized. In step S2 of this application, when it is necessary to reduce the rear axle energy recovery braking force, i.e., when the current rear axle energy recovery braking force exceeds the upper limit of the longitudinal braking force, the rear axle energy recovery braking force is reduced to be equal to the upper limit of the longitudinal braking force. This method minimizes the reduction in rear axle energy recovery braking force, maintaining the maximum rear axle energy recovery braking force while ensuring vehicle stability, thus enabling efficient braking energy recovery and improving the vehicle's range.

[0040] In this case, the upper limit of longitudinal braking force is the maximum value that the rear axle energy recovery braking force can reach, that is, the critical value that the rear axle does not exceed the adhesion limit. By maintaining the rear axle energy recovery braking force at the maximum level under the current conditions, energy recovery is maximized while ensuring vehicle stability, thereby maximizing the energy recovery efficiency and improving the vehicle's range.

[0041] In step S3 of this application, when it is necessary to increase the rear axle energy recovery braking force, that is, when the upper limit of the longitudinal braking force exceeds the current rear axle energy recovery braking force, the rear axle energy recovery braking force is increased to be equal to the upper limit of the longitudinal braking force. This method of increase can quickly increase the rear axle energy recovery braking force to the maximum extent, ensuring the most efficient recovery and utilization of braking energy, and further improving the driving range.

[0042] In the current state, if the upper limit of longitudinal braking force increases, increasing the rear axle energy recovery braking force can improve energy recovery efficiency. The limit that the rear axle energy recovery braking force can be increased in the current state is either the current upper limit of longitudinal braking force or the target braking force. That is, if the current upper limit of longitudinal braking force exceeds the target braking force, the rear axle energy recovery braking force is increased to the target braking force. If the current upper limit of longitudinal braking force is less than the target braking force, the rear axle energy recovery braking force is increased to the current upper limit of longitudinal braking force. In either case, the rear axle energy recovery braking force is kept at its maximum to recover braking energy to the greatest extent and further improve range.

[0043] In a preferred embodiment of this application, the method for the upper limit of longitudinal braking force in step S1 above, where the rear wheels of the vehicle remain stable on the current driving road without exceeding the adhesion limit, is optimized. Specifically, this embodiment first calculates the dynamic load of the rear axle and the lateral force of the rear wheels based on the collected vehicle driving parameters, and calculates the dynamic load of the rear axle according to the following formula: in: F r —Rear axle dynamic load, N; F r0 — Rear axle static load, N; m —Total vehicle weight, kg, obtained through sensors on the vehicle's suspension. h g —Vehicle center of gravity height, in meters, obtained from vehicle design parameters; z —Target vehicle deceleration, m / s 2 This is calculated using the brake pedal sensor. θ —The slope angle of the current road is obtained by the tilt sensor on the vehicle. L — Wheelbase, in meters, is obtained from vehicle design parameters.

[0044] The rear wheel lateral force is calculated based on the collected vehicle driving parameters, including steering wheel angle, steering wheel angle change rate, and vehicle speed. The steering wheel angle signal of the EPS is acquired in real time via CAN signal, and the steering wheel angle and steering wheel angle change rate can be obtained from this signal. The current vehicle speed is obtained using wheel speed sensors. The vehicle steering curvature and rear wheel lateral force are calculated using a dynamic model (in this embodiment, the dynamic model is a calculation model built based on the vehicle structure; simulation software is used to simulate and analyze the vehicle steering curvature and rear wheel lateral force at various steering angles, constructing a dynamic model of steering angle, vehicle steering curvature, and rear wheel lateral force, which is stored in the vehicle controller for direct use later). The rear wheel lateral force is positively correlated with steering wheel angle, steering wheel angle change rate, and vehicle speed; the tire lateral force increases significantly during high-speed, large-angle steering or rapid steering.

[0045] The rear wheel lateral force calculated in this embodiment refers to the rear wheel lateral force required to maintain the current steering curvature and vehicle speed during steering.

[0046] After calculating the dynamic load on the rear axle and the lateral force on the rear wheels, the upper limit of the longitudinal braking force can be calculated using the following formula: in: F xmax —The maximum longitudinal braking force (in N) required for the rear wheels of a vehicle to remain stable on the road without exceeding the adhesion limit; μ —The road surface adhesion coefficient of the current driving road can be estimated based on the wheel speed through the ESC system, or it can be estimated based on road surface recognition and other methods; F r —Rear axle dynamic load, N; F y —Rear wheel lateral force, N.

[0047] In practice, the energy recovery control for a rear-wheel-drive vehicle according to this application can be operated as follows: When the vehicle is turning and braking, vehicle driving parameters are collected, including steering wheel angle signal, brake pedal signal, steering wheel angle change rate, vehicle speed, road slope angle, and road surface adhesion coefficient. Based on the above parameters, the dynamic load on the rear axle and the lateral force on the rear wheels are calculated when the vehicle is turning and braking is requested. The upper limit of the longitudinal braking force when the rear wheels of the vehicle remain stable on the current driving road without exceeding the adhesion limit is calculated according to the above formula. If the current rear axle energy recovery braking force exceeds the upper limit of the longitudinal braking force when the rear axle friction braking is not engaged, the rear axle energy recovery braking force is reduced to not exceed the upper limit of the longitudinal braking force, and then reduced to be equal to the upper limit of the longitudinal braking force. At the same time, the front axle braking force is increased to keep the total braking force of the vehicle unchanged. If the upper limit of the longitudinal braking force exceeds the current rear axle energy recovery braking force, the rear axle energy recovery braking force is increased to be equal to the upper limit of the longitudinal braking force, while the front axle braking force is reduced to keep the total braking force of the vehicle constant.

[0048] When comparing the rear axle energy recovery braking force with the upper limit of the longitudinal braking force, the electromechanical brake controller monitors the recovery torque output by the rear axle energy recovery system in real time and converts it into the corresponding longitudinal energy recovery braking force (converted by tire radius: rear axle energy recovery braking force = rear axle energy recovery torque / rear tire rolling radius).

[0049] This application also relates to a rear-wheel drive vehicle energy recovery control system, which can be integrated into the vehicle's controller and controlled by the vehicle controller. The rear-wheel-drive vehicle energy recovery control system of this application includes a data acquisition module, a limit calculation module, a condition judgment module, a first comparison module, a first rear axle adjustment module, and a first front axle adjustment module. The data acquisition module is used to acquire vehicle driving parameters when the vehicle is turning and braking. The limit calculation module is used to calculate the upper limit of longitudinal braking force when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current driving road, based on the vehicle driving parameters. The condition judgment module determines whether the starting condition is met based on the vehicle's rear axle braking force data, if the rear axle friction braking has not been engaged, otherwise it determines that the starting condition is not met. The first comparison module is used to compare the current rear axle energy recovery braking force with the upper limit of longitudinal braking force. The first rear axle adjustment module is used to reduce the rear axle energy recovery braking force so that it does not exceed the upper limit of longitudinal braking force when the starting condition is met and the current rear axle energy recovery braking force exceeds the upper limit of longitudinal braking force. The first front axle adjustment module is used to increase the front axle braking force when the rear axle energy recovery braking force is reduced so that the total braking force of the vehicle remains unchanged.

[0050] The first rear axle adjustment module is used to reduce the energy recovery braking force of the rear axle to be equal to the upper limit of the longitudinal braking force.

[0051] In addition, the energy recovery control system for rear-wheel drive vehicles in this application also includes a second comparison module, a second rear axle adjustment module, and a second front axle adjustment module. The second comparison module is used to compare the current rear axle energy recovery braking force with the upper limit of the longitudinal braking force again. The second rear axle adjustment module is used to increase the rear axle energy recovery braking force when the current rear axle energy recovery braking force is lower than the upper limit of the longitudinal braking force. The second front axle adjustment module is used to reduce the front axle braking force when the rear axle energy recovery braking force increases so that the total braking force of the vehicle remains unchanged.

[0052] The second rear axle adjustment module is used to increase the energy recovery braking force of the rear axle to make it equal to the upper limit of the longitudinal braking force.

[0053] The limit calculation module of this application calculates the dynamic load on the rear axle and the lateral force on the rear wheels based on the collected vehicle driving parameters, and calculates the upper limit of the longitudinal braking force according to the following formula: in: F xmax —The upper limit of longitudinal braking force when the rear wheels of a vehicle remain stable and do not exceed the adhesion limit on the current road surface; μ —The road surface adhesion coefficient of the current driving road; F r —Rear axle dynamic load; F y —Rear wheel lateral force.

[0054] The method for calculating the dynamic load on the rear axle of a vehicle based on the collected vehicle driving parameters in this application includes: calculating the dynamic load on the rear axle according to the following formula: in: F r —Rear axle dynamic load; F r0 — Rear axle static load; m —Total vehicle weight; h g —Vehicle center of gravity height; z —Target for vehicle deceleration; θ —The gradient angle of the current road; L — Wheelbase.

[0055] μ—The road surface adhesion coefficient of the current driving road; F y —Rear wheel lateral force.

[0056] In practical applications, the electromechanical braking module in the vehicle control system monitors the recovery torque output by the rear axle energy recovery system in real time and converts it into the corresponding rear axle energy recovery braking force (calculated using tire radius: rear axle energy recovery braking force = rear axle energy recovery torque / tire rolling radius). When the rear axle energy recovery braking force exceeds the upper limit F of the longitudinal braking force required for the rear wheels to remain stable and not exceed the adhesion limit on the current road surface... xmax At that time, it was determined that there was a risk of the rear axle exceeding the adhesion limit.

[0057] The electromechanical braking control module identifies a risk of the rear axle exceeding its adhesion limit and sends a request to the rear axle energy recovery system to reduce the negative torque of energy recovery. Simultaneously, it coordinates the front axle braking force to compensate for the reduced negative torque and sends a clamping force request to the front wheel electromechanical braking module. This ensures that the reduced rear axle energy recovery braking force is compensated for by the front axle braking force, keeping the total vehicle braking force constant (stable deceleration) and preventing the driver from perceiving any jerking or deceleration fluctuations. By transferring a portion of the rear axle's energy recovery braking torque to the front axle, the distribution of braking force between the front and rear axles is altered, reducing the longitudinal braking force on the rear axle and thus ensuring sufficient lateral force support for the rear axle. This process is controlled and responded to in milliseconds by the electromechanical braking module. Furthermore, the absence of hydraulic delay in the electromechanical braking execution module and the independent generation of clamping force by the front and rear wheels ensure a smooth transfer of braking force from the rear wheels to the front wheels.

[0058] The entire control system continuously monitors gradient, road surface adhesion conditions, vehicle speed, steering wheel angle, and longitudinal deceleration requirements, and calculates changes in rear axle dynamic load and rear wheel lateral force in real time. If the recalculated longitudinal braking force F is the upper limit value for maintaining stability of the vehicle's rear wheels without exceeding the adhesion limit on the current driving road surface... xmax When the energy recovery braking force exceeds the current rear axle energy, the limit is determined to be in a state of recovery.

[0059] As the upper limit of longitudinal braking force increases, the front axle braking force transferred to the front axle is gradually transferred to the rear axle energy recovery braking force. The electromechanical braking control module executes the transfer logic in reverse, gradually reducing the clamping force of the front wheel electromechanical braking while increasing the rear axle energy recovery torque until the braking force originally replaced by the front axle is completely transferred back to the rear axle. The total braking force remains stable, and the energy recovery braking of the rear axle is restored to ensure the energy recovery utilization rate of the vehicle.

[0060] When the regenerative braking force from the rear axle is transferred to the front axle, priority is given to providing sufficient lateral adhesion to the rear axle to ensure its lateral stability. When the braking force is transferred from the front axle friction braking to the rear axle regenerative braking, priority is given to reducing the rate of torque change to ensure vehicle ride comfort.

[0061] like Figure 2 As shown, when a braking request occurs, the target braking force is obtained based on the brake pedal signal. The target braking force of this application does not exceed the maximum energy recovery braking force of the rear axle energy recovery braking module. The rear axle energy recovery braking force gradually increases over time until it reaches the target braking force. During this process, the target braking force is fully allocated to the rear axle energy recovery braking. As the steering wheel angle increases, in order to ensure the lateral adhesion of the rear wheels, the rear axle braking force is limited. At time T1, the current rear axle energy recovery braking force is higher than the upper limit of the longitudinal braking force when the rear wheels of the vehicle remain stable on the current driving road without exceeding the adhesion limit. The electromechanical braking control module begins to request a reduction in the rear axle energy recovery braking force, and the front wheel electromechanical calipers generate friction braking force. The compensated friction braking force is equal to the reduced portion of the rear axle energy recovery braking force, thereby ensuring that the total braking force remains unchanged and is still the target braking force. At time T2, the demand for lateral force on the rear wheels is reduced, and the energy recovery braking force of the rear axle is increased to the current upper limit of the longitudinal braking force or the target braking force. The mechanical friction braking force of the front wheels is reduced, and the energy recovery feedback braking force is transferred back to the rear axle, so that the total braking force still meets the target braking force.

[0062] The energy recovery control method for rear-wheel drive vehicles in this application is mainly applied when the vehicle is turning and has a braking request. By comparing the current rear-wheel drive energy recovery braking force with the upper limit of the longitudinal braking force when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current driving road, if the current rear-wheel drive energy recovery braking force exceeds the upper limit of the longitudinal braking force, it proves that the rear wheels of the vehicle are at risk of exceeding the adhesion limit, which may lead to instability problems such as fishtailing. In order to avoid this situation, this application can effectively control the rear-wheel drive energy recovery braking force. When there is a risk of the rear axle exceeding the adhesion limit, the rear axle energy recovery braking force can be reduced while the front axle braking force is increased simultaneously. This maintains the total braking force between the front and rear axles unchanged, always meeting the target braking force requirement, improving the lateral stability of the vehicle, avoiding fishtailing and ensuring vehicle driving safety. By utilizing the advantages of electromechanical braking, the total deceleration remains unchanged during the braking force transfer process, eliminating the driver's sense of jerking.

[0063] When the longitudinal braking force limit changes while the rear wheels of a vehicle remain stable on the road without exceeding the adhesion limit, exceeding the current rear-wheel drive energy recovery braking force, this application increases the rear-wheel drive energy recovery braking force and then decreases the front axle braking force to maintain a constant total braking force, always meeting the target braking force requirement. The deceleration of the vehicle remains constant, preventing any jerking. Furthermore, the rapidly increased rear-wheel drive energy recovery braking force significantly improves the vehicle's braking energy recovery efficiency, maximizing the recovery of energy during braking and improving the vehicle's driving range and energy utilization efficiency.

[0064] The braking request in this application includes both the braking force request from pressing the brake pedal, the braking request from the external controller, and the coasting braking request after the driver releases the accelerator pedal. The braking request target is equal to the sum of the driver's braking request or the external controller's braking request and the coasting braking request.

[0065] This application provides a rear-wheel drive vehicle energy recovery control device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, which are executed by the at least one processor to enable the at least one processor to perform the rear-wheel drive vehicle energy recovery control method in the above embodiments.

[0066] The following is for reference. Figure 3 This document illustrates a structural schematic diagram of a rear-wheel-drive vehicle energy recovery control device suitable for implementing embodiments of this application. The rear-wheel-drive vehicle energy recovery control device in this application embodiment may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 3 The energy recovery control device for rear-wheel drive vehicles shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments of this application.

[0067] like Figure 3As shown, the rear-wheel-drive vehicle energy recovery control device may include a processing unit 1001 (e.g., a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the rear-wheel-drive vehicle energy recovery control device. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the rear-wheel-drive vehicle energy recovery control device to communicate wirelessly or wiredly with other devices to exchange data. Although a rear-wheel-drive vehicle energy recovery control device with various systems is shown in the figure, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems may be implemented alternatively.

[0068] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0069] The rear-wheel drive vehicle energy recovery control device provided in this application, employing the rear-wheel drive vehicle energy recovery control method described in the above embodiments, can solve the technical problem of energy recovery control in rear-wheel drive vehicles. Compared with the prior art, the beneficial effects of the rear-wheel drive vehicle energy recovery control device provided in this application are the same as those of the rear-wheel drive vehicle energy recovery control method provided in the above embodiments, and other technical features of this rear-wheel drive vehicle energy recovery control device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0070] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0071] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0072] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the rear-wheel drive vehicle energy recovery control method in the above embodiments.

[0073] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0074] The aforementioned computer-readable storage medium may be included in the energy recovery control device for a rear-wheel drive vehicle; or it may exist independently and not be installed in the energy recovery control device for a rear-wheel drive vehicle.

[0075] The aforementioned computer-readable storage medium carries one or more programs that, when executed by the rear-wheel-drive vehicle energy recovery control device, cause the rear-wheel-drive vehicle energy recovery control device to: collect vehicle driving parameters, including steering wheel angle signal, brake pedal signal, steering wheel angle change rate, vehicle speed, road slope angle, and road surface adhesion coefficient, when the vehicle is turning and braking; calculate the rear axle dynamic load and rear wheel lateral force of the vehicle under turning and braking request conditions based on the aforementioned parameters; and calculate the stability of the vehicle's rear wheels on the current driving road according to the aforementioned formula. The upper limit of longitudinal braking force when the adhesion limit is broken; if the current rear axle energy recovery braking force exceeds the upper limit of longitudinal braking force when the rear axle friction braking is not engaged, the rear axle energy recovery braking force is reduced to not exceed the upper limit of longitudinal braking force, and then reduced to be equal to the upper limit of longitudinal braking force, while the front axle braking force is increased to keep the total braking force of the vehicle unchanged; if the upper limit of longitudinal braking force exceeds the current rear axle energy recovery braking force, the rear axle energy recovery braking force is increased to be equal to the upper limit of longitudinal braking force, and the front axle braking force is reduced to keep the total braking force of the vehicle unchanged.

[0076] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server.

[0077] In cases involving remote computers, the remote computer can be connected to the user's computer through any type of network—including a local area network (LAN) or a wide area network (WAN)—or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0078] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0079] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0080] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described rear-wheel drive vehicle energy recovery control method, thereby solving the technical problem. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the rear-wheel drive vehicle energy recovery control method provided in the above embodiments, and will not be repeated here.

[0081] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the rear-wheel drive vehicle energy recovery control method described above.

[0082] The computer program product provided in this application can solve the technical problem. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the energy recovery control method for rear-wheel drive vehicles provided in the above embodiments, and will not be repeated here.

[0083] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A method for controlling energy recovery in a rear-wheel-drive vehicle, characterized in that: include, When the vehicle is turning and braking, the vehicle driving parameters are collected, and the upper limit of longitudinal braking force, rear axle energy recovery braking force and target braking force are calculated when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current driving road. If the current rear axle energy recovery braking force exceeds the longitudinal braking force limit when the rear axle friction braking is not engaged, the rear axle energy recovery braking force is reduced to not exceed the longitudinal braking force limit, while the front axle braking force is increased to keep the total braking force of the front and rear vehicles constant.

2. The energy recovery control method for a rear-wheel drive vehicle as described in claim 1, characterized in that: When the current rear axle energy recovery braking force exceeds the upper limit of the longitudinal braking force, the rear axle energy recovery braking force is reduced to be equal to the upper limit of the longitudinal braking force.

3. The energy recovery control method for a rear-wheel drive vehicle as described in claim 1, characterized in that: If the upper limit of the longitudinal braking force exceeds the current energy recovery braking force of the rear axle, then the braking force of the front axle is reduced and the energy recovery braking force of the rear axle is increased, so that the total braking force of the front and rear vehicles remains unchanged.

4. The energy recovery control method for a rear-wheel drive vehicle as described in claim 3, characterized in that: When the upper limit of the longitudinal braking force exceeds the current rear axle energy recovery braking force, increase the rear axle energy recovery braking force to make it equal to the upper limit of the longitudinal braking force or equal to the target braking force.

5. The energy recovery control method for a rear-wheel drive vehicle as described in claim 1, characterized in that: The method for calculating the upper limit of longitudinal braking force when the rear wheels of a vehicle remain stable and do not exceed the adhesion limit on the current driving road includes: calculating the dynamic load on the rear axle and the lateral force on the rear wheels based on the collected vehicle driving parameters, and calculating the upper limit of longitudinal braking force according to the following formula: in: F xmax —The upper limit of longitudinal braking force when the rear wheels of a vehicle remain stable and do not exceed the adhesion limit on the current road surface; μ —The road surface adhesion coefficient of the current driving road; F r —Rear axle dynamic load; F y —Rear wheel lateral force.

6. The energy recovery control method for a rear-wheel drive vehicle as described in claim 5, characterized in that: The method for calculating the dynamic load on the rear axle of a vehicle based on the collected vehicle driving parameters includes: calculating the dynamic load on the rear axle according to the following formula: in: F r —Rear axle dynamic load; F r0 — Rear axle static load; m —Total vehicle weight; h g —Vehicle center of gravity height; z —Target for vehicle deceleration; θ —The gradient angle of the current road; L — Wheelbase.

7. The energy recovery control method for a rear-wheel drive vehicle as described in claim 5, characterized in that: The method for calculating the lateral force of the rear wheels of a vehicle based on the collected vehicle driving parameters includes: calculating the lateral force of the rear wheels of the vehicle based on the steering wheel angle, the rate of change of the steering wheel angle, and the vehicle speed in the collected vehicle driving parameters.

8. An energy recovery control system for a rear-wheel drive vehicle, characterized in that: The control system operates according to any one of the energy recovery control methods for rear-wheel drive vehicles as described in claims 1 to 7. include, The data acquisition module is used to collect vehicle driving parameters when the vehicle is turning and braking. The limit calculation module is used to calculate the upper limit of longitudinal braking force, rear axle energy recovery braking force, and target braking force when the rear wheels of the vehicle remain stable and do not exceed the adhesion limit on the current driving road, based on the vehicle driving parameters. The condition judgment module determines whether the starting conditions are met based on the vehicle's rear axle braking force data, and determines that the starting conditions are not met if the vehicle's rear axle friction braking is not engaged. The first comparison module is used to compare the current rear axle energy recovery braking force with the upper limit value of the longitudinal braking force; The first rear axle adjustment module is used to reduce the rear axle energy recovery braking force so that it does not exceed the upper limit of the longitudinal braking force when the start-up conditions are met and the current rear axle energy recovery braking force exceeds the upper limit of the longitudinal braking force. The first front axle adjustment module is used to increase the front axle braking force when the rear axle energy recovery braking force decreases, so that the total braking force of the vehicle before and after adjustment remains unchanged.

9. The energy recovery control system for a rear-wheel drive vehicle as described in claim 8, characterized in that: The first rear axle adjustment module is used to reduce the energy recovery braking force of the rear axle to be equal to the upper limit of the longitudinal braking force.

10. The energy recovery control system for a rear-wheel drive vehicle as described in claim 8, characterized in that: It also includes, The second comparison module is used to compare the current rear axle energy recovery braking force with the upper limit of the longitudinal braking force again. The second rear axle adjustment module is used to increase the rear axle energy recovery braking force when the current rear axle energy recovery braking force is lower than the upper limit of the longitudinal braking force. The second front axle adjustment module is used to reduce the front axle braking force when the rear axle energy recovery braking force increases, so that the total braking force of the vehicle before and after adjustment remains unchanged.

11. The energy recovery control system for a rear-wheel drive vehicle as described in claim 10, characterized in that: The second rear axle adjustment module is used to increase the rear axle energy recovery braking force to make it equal to the upper limit of the longitudinal braking force or equal to the target braking force.

12. The energy recovery control system for a rear-wheel drive vehicle as described in claim 8, characterized in that: The limit calculation module calculates the dynamic load on the rear axle and the lateral force on the rear wheels based on the collected vehicle driving parameters, and calculates the upper limit of the longitudinal braking force according to the following formula: in: F xmax —The upper limit of longitudinal braking force when the rear wheels of a vehicle remain stable and do not exceed the adhesion limit on the current road surface; μ —The road surface adhesion coefficient of the current driving road; F r —Rear axle dynamic load; F y —Rear wheel lateral force.

13. The energy recovery control system for a rear-wheel drive vehicle as described in claim 12, characterized in that: The method by which the limit calculation module calculates the dynamic load on the rear axle of the vehicle based on the collected vehicle driving parameters includes: calculating the dynamic load on the rear axle according to the following formula: in: F r —Rear axle dynamic load; F r0 — Rear axle static load; m —Total vehicle weight; h g —Vehicle center of gravity height; z —Target for vehicle deceleration; θ —The gradient angle of the current road; L —Wheelbase; μ —The road surface adhesion coefficient of the current driving road; F y —Rear wheel lateral force.

14. An electronic device, characterized in that: It includes a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute a rear-wheel drive vehicle energy recovery control method as described in any one of claims 1 to 7.

15. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the energy recovery control method for a rear-wheel drive vehicle as described in any one of claims 1 to 7.

16. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the steps of a rear-wheel drive vehicle energy recovery control method as described in any one of claims 1 to 7.

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