Braking force distribution control method and system, medium and product

Abstract

The invention relates to the technical field of automobile control, in particular to a braking force distribution control method and system, a medium and a product. The method includes: acquiring total braking force of a vehicle according to a braking signal; the maximum energy recovery feedback braking force allowed by the rear axle is determined; determining a preset front axle braking force and a first braking force distribution coefficient; in the initial stage of braking force request, the rear axle energy recovery feedback braking force is controlled to be the unique braking force; and if the rear axle energy recovery feedback braking force is increased to the maximum energy recovery feedback braking force and still does not meet the total braking force requirement, the front axle braking force is rapidly increased according to the first braking force distribution coefficient, and the rear axle friction braking force is slowly increased. According to the braking force distribution control method, different braking force distribution modes are adopted for different stages after the braking request, the problems of poor stability of the vehicle, working noise caused by premature activation of the ABS and the like are avoided, and the braking performance on wet and slippery asphalt pavements and the like is improved.

Description

Technical Field

[0001] This invention relates to the field of automotive control technology, specifically to a braking force distribution control method, system, medium, and product. Background Technology

[0002] In the field of new energy vehicle braking technology, electromechanical braking pure dry brake-by-wire solutions are gradually maturing and moving towards mass production. This solution, with its ability to flexibly apply braking independently to all four wheels, provides ample room for optimizing the vehicle's braking force distribution. Traditional EHB braking force distribution in new energy rear-wheel-drive vehicles faces numerous challenges, requiring solutions through optimized braking force distribution control of electromechanical braking systems.

[0003] In new energy rear-wheel drive vehicles, the combined effects of rear axle coasting energy recovery and braking energy recovery result in excessively high regenerative braking force on the rear wheels. If friction braking is further applied, the excessive rear-wheel braking force, coupled with the forward transfer of axle load, makes the rear wheels prone to exceeding the road surface adhesion limit, leading to an increased slip ratio and even frequent triggering of the ABS anti-lock braking system. Under complex conditions of medium-heavy braking accompanied by large-angle steering, the rear wheels may exceed lateral adhesion, potentially causing the vehicle to skid and fishtail, seriously threatening driving safety. Current technology lacks sufficient research on braking force distribution in rear-wheel drive new energy vehicles, necessitating the development of a novel technical solution to address the braking force distribution challenges in electromechanical braking of new energy rear-wheel drive models, thereby improving vehicle driving safety and stability. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of the aforementioned background technology and provide a braking force distribution control method, system, medium, and product.

[0005] The technical solution of this application is: a braking force distribution control method, comprising, After a braking request is issued, the total braking force of the vehicle is obtained based on the braking signal. Determine the maximum permissible energy recovery braking force on the rear axle; The preset front axle braking force is determined based on the critical locking braking force of the front axle on a road surface with a given adhesion coefficient, and the first braking force distribution coefficient is determined. In the initial stage of braking force request, the rear axle energy recovery feedback braking force is controlled as the only braking force, and the rear axle energy recovery feedback braking force is gradually increased. If the maximum energy recovery braking force of the rear axle is still insufficient to meet the total braking force requirement, then the front axle braking force will be rapidly increased and the rear axle friction braking force will be slowly increased according to the first braking force distribution coefficient.

[0006] According to the braking force distribution control method provided in this application, the critical front axle braking force is determined based on the critical lock-up braking force of the front axle on a high-adhesion road surface, and the second braking force distribution coefficient is determined. If the front axle braking force reaches the preset front axle braking force but still does not meet the total braking force requirement, then the front axle braking force and the rear axle friction braking force are increased according to the second braking force distribution coefficient.

[0007] According to the braking force distribution control method provided in this application, a calibration test is conducted on a road surface with a given adhesion coefficient. The braking force of the front axle when both the front and rear axles lock up simultaneously under no-load conditions is the preset front axle braking force, and the product of the braking force of the rear axle lock up and a set threshold is the preset rear axle braking force; the set threshold is less than 1.

[0008] According to the braking force distribution control method provided in this application, the method for determining the first braking force distribution coefficient includes: using the difference between the preset rear axle braking force and the maximum energy recovery feedback braking force as the calculated value of the rear axle friction braking force; and using the ratio of the preset front axle braking force to the sum of the preset front axle braking force and the calculated value of the rear axle friction braking force as the first braking force distribution coefficient.

[0009] According to the braking force distribution control method provided in this application, the method for determining the second braking force distribution coefficient includes: based on the critical locking braking forces of the front axle and the rear axle on a high-adhesion road surface as the critical front axle braking force and the critical rear axle braking force; calculating a first difference between the critical front axle braking force and the preset front axle braking force; calculating a second difference between the critical rear axle braking force and the preset rear axle braking force; and using the ratio of the first difference to the sum of the first difference and the second difference as the second braking force distribution coefficient.

[0010] According to the braking force distribution control method provided in this application, the method of gradually increasing the rear axle energy recovery feedback braking force includes: gradually increasing the rear axle energy recovery feedback braking force from zero to the maximum energy recovery feedback braking force or to the total braking force according to a set rising speed.

[0011] This application also relates to a brake force distribution control system, wherein the control method operates according to the aforementioned brake force distribution control method, including... A braking request identification module is used to identify whether a braking request exists, and to obtain the total braking force of the vehicle based on the braking signal after the braking request occurs. A maximum regenerative braking force determination module is used to determine the maximum allowable energy recovery braking force of the rear axle. A preset front axle braking force determination module determines the preset front axle braking force based on the critical lock-up braking force of the front axle on a road surface with a given adhesion coefficient. The first braking distribution coefficient determination module determines the first braking force distribution coefficient based on a preset front axle braking force. The first adjustment module is used to control the rear axle energy recovery feedback braking force as the only braking force in the initial stage of braking force request, and gradually increase the rear axle energy recovery feedback braking force. The second adjustment module is used to rapidly increase the front axle braking force and slowly increase the rear axle friction braking force according to the first braking force distribution coefficient when the rear axle energy recovery feedback braking force is increased to the maximum energy recovery feedback braking force but still does not meet the total braking force requirement.

[0012] The braking force distribution control system provided in this application further includes, A critical front axle braking force determination module is used to determine the critical front axle braking force based on the critical lock-up braking force of the front axle on a high-adhesion road surface. The second braking distribution coefficient determination module determines the second braking force distribution coefficient based on the critical front axle braking force. The third adjustment module is used to increase the front axle braking force and the rear axle friction braking force according to the second braking force distribution coefficient when the front axle braking force reaches the preset front axle braking force but still does not meet the total braking force requirement.

[0013] 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 braking force distribution control method.

[0014] This application also relates to a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described braking force distribution control method.

[0015] 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 braking force distribution control method.

[0016] The advantages of this application are as follows: 1. This application adopts four-wheel electromechanical braking for rear-wheel drive vehicles. When there is a braking request, different braking force is distributed in different stages. In the initial stage, the energy recovery and feedback braking force of the rear axle is used as the only braking force to maximize energy recovery. When the energy recovery and feedback braking force of the rear axle is increased to the maximum extent, the braking force of the front axle and the friction braking force of the rear axle are increased. The increase is carried out synchronously according to the calculated first braking force distribution coefficient. The front axle braking force is controlled to increase rapidly and significantly, while the rear axle friction braking force is controlled to increase slowly and slightly. This avoids problems such as the increase in rear wheel friction braking force, which leads to the superposition of friction braking and regenerative braking, resulting in an increase in rear wheel slip rate, which causes poor vehicle stability and premature ABS activation, resulting in operating noise. This improves the braking performance of the vehicle on wet and slippery asphalt and other road surfaces, and improves the user's driving experience. 2. This application optimizes the situation after the front axle braking force reaches the preset front axle braking force. By continuing to increase the front axle braking force and the rear axle braking force to meet the required braking demand, the front axle braking force and the rear axle braking force can quickly meet the driver's target braking force requirements. While maintaining vehicle stability, the time of rear wheel lock-up is delayed to the greatest extent. 3. This application obtains the required preset front axle braking force and preset rear axle braking force by constructing standard tests. The preset front axle braking force is the critical locking braking force of the front axle on a road surface with a given coefficient of adhesion. It is the critical point for braking force distribution. Based on the preset front axle braking force, different stages of braking force distribution control can be performed, thereby avoiding problems such as working noise caused by premature activation of ABS. The preset rear axle braking force obtained in this application is set based on the critical locking braking force of the rear axle on a road surface with a given coefficient of adhesion. It is less than the critical locking braking force of the rear axle. That is to say, even if the rear axle braking force reaches the preset rear axle braking force, it will not cause the rear axle to lock up, further improving the stability of the vehicle. 4. This application calculates the first braking force distribution coefficient based on the preset front axle braking force, the preset rear axle braking force, and the maximum energy recovery feedback braking force. The first braking force distribution coefficient is the distribution coefficient before the front axle braking force reaches the preset front axle braking force. Since the front axle braking force is significantly greater than the rear axle braking friction force, when the front axle braking force and the rear axle braking friction force are increased simultaneously based on the first braking force distribution coefficient, the front axle braking force can increase significantly and rapidly, while the rear axle friction braking force can only increase slightly and slowly. This avoids the slippage problem caused by the rapid increase of the rear axle braking force. Moreover, the first braking force distribution coefficient is easy to calculate and simple to operate. 5. The second braking force distribution coefficient of this application is calculated based on the critical front axle braking force, the critical rear axle braking force, the preset front axle braking force, and the preset rear axle braking force. By controlling the front axle braking force and the rear axle braking force based on the second braking force distribution coefficient, the front axle braking force can be made infinitely close to the critical front axle braking force, so that the front axle braking force and the rear axle braking force can quickly meet the driver's target braking force requirements, delay ABS activation to the greatest extent, improve vehicle stability, and the control based on the second braking force distribution coefficient is extremely convenient and the operation is extremely simple. 6. In the initial stage of braking force distribution, this application gradually increases the rear axle energy recovery braking force according to the set overload rate, so that the rear axle energy recovery braking force can be increased steadily and gradually, improving the smoothness of the vehicle in the initial braking stage and avoiding jerking. 7. This application also relates to a brake force distribution control system. The brake force distribution control system of this application operates according to the above-mentioned brake force distribution control method and can be integrated into the vehicle control system. This facilitates the vehicle control system to distribute and control the braking force of the vehicle during actual driving, and can effectively improve the stability and safety of the vehicle. 8. The brake force distribution control system of this application integrates multiple adjustment modules, each corresponding to a different control stage. Different brake force distribution modes are used in different control stages to control brake force distribution, which can effectively and precisely control different stages. In the initial stage of brake force request, energy recovery can be maximized. Before the front axle brake force increases to the preset front axle brake force, the stability of the rear axle can be maintained to avoid instability. After the front axle brake force exceeds the preset front axle brake force, the front axle brake force can be brought as close as possible to the critical front axle brake force, delaying ABS activation to the greatest extent and improving vehicle stability. 9. This application also provides a control device that can be integrated into a vehicle control system with an electromechanical braking module to form a matching software module. It can automatically control the braking force distribution between the front axle and rear axle of the vehicle without any human intervention, thereby maximizing the efficiency of energy recovery and ensuring the stability of the vehicle during braking. It also delays the activation time of ABS as much as possible, thereby improving the overall stability and safety of the vehicle. 10. This application also relates to a non-transitory computer-readable storage medium, which stores a corresponding computer program, facilitating the vehicle control system to perform corresponding control operations based on the stored computer program, thereby significantly improving the stability and safety of vehicles equipped with electromechanical braking systems.

[0017] The braking force distribution control method of this application is simple. Different braking force distribution methods are adopted for different stages after the braking request, which can maximize energy recovery. At the same time, it avoids problems such as the increase in rear wheel slip rate caused by the superposition of friction braking and regenerative braking, which leads to poor vehicle stability and premature ABS activation, resulting in operating noise. It improves the braking performance of the vehicle on wet and slippery asphalt and other road surfaces. Attached Figure Description

[0018] Figure 1 : A schematic diagram of the braking force distribution control method of this application; Figure 2 The diagram shows the changes in rear axle energy recovery braking force, front axle braking force, and rear axle friction braking force at different stages during the braking force request process in this application. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] This application relates to a braking force distribution control method, which is mainly 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 the rear axle is equipped with an energy recovery and feedback module. When a braking request occurs, the rear axle energy recovery and feedback module, as well as the electromechanical braking modules of the front and rear axles, can provide braking force to the vehicle. This application distributes braking force to the front axle and rear axle braking force according to different stages of the braking request. The rear axle braking force includes the rear axle energy recovery and feedback braking force and the rear axle friction braking force. In the initial stage of braking request, energy recovery is maximized; in the middle stage of braking request, the front axle braking force is controlled to increase rapidly, while the rear axle friction braking force is controlled to increase slowly. This avoids problems such as decreased vehicle stability and premature ABS activation due to excessively rapid increase in rear wheel friction braking force, which could lead to the superposition of friction braking and regenerative braking. This also improves the vehicle's braking performance on slippery surfaces such as wet asphalt, enhancing the user's driving experience; in the final stage of braking request, the front axle braking force is controlled to approach the critical front axle braking force as closely as possible, delaying ABS activation as much as possible while maintaining vehicle stability.

[0024] Specifically, such as Figures 1-2 As shown, a braking force distribution control method of this application includes the following steps: S1. After a braking request occurs, the total braking force of the vehicle is obtained based on the braking signal. The maximum allowable energy recovery braking force of the rear axle is determined. The preset front axle braking force is determined based on the critical lock-up braking force of the front axle on a road surface with a given coefficient of adhesion (in this application, the given coefficient of adhesion is a wet and slippery public road surface with a given coefficient of adhesion of 0.4 to 0.5). The first braking force distribution coefficient is also determined. Once a braking force request is made, i.e. the driver presses the brake pedal, the total braking force of the vehicle expected by the driver can be obtained based on the braking signal after this braking signal is detected. The preset front axle braking force and the maximum energy recovery braking force are obtained through calibration and stored in the control system in advance. They can be recalled when needed. The first braking force distribution coefficient is calculated. S2. In the initial stage of braking force request, control the rear axle energy recovery feedback braking force as the only braking force, and gradually increase the rear axle energy recovery feedback braking force. After a braking request is detected, the braking force is gradually increased. It does not reach the required total braking force at the beginning. In the initial stage of the braking force request, the rear axle energy recovery feedback module is called first to recover braking energy to the maximum extent. The rear axle energy recovery module recovers energy in two ways: coasting energy recovery and braking energy recovery. Braking energy recovery and coasting energy recovery work together on the rear axle, achieving a maximum braking deceleration of 0.3g (example data, actual application is not limited to this value), covering more than 96% of braking conditions. The rear axle energy recovery module generates braking deceleration without the need for electromechanical braking, thus avoiding the risk of lock-up due to excessive negative torque on the rear wheels and excessive braking force distribution on the rear axle. The initial stage of the braking force request corresponds to the range from zero to the maximum energy recovery braking force of the rear axle. S3. If the energy recovery braking force of the rear axle is increased to the maximum energy recovery braking force but still does not meet the total braking force requirement, then the front axle braking force is increased rapidly and the rear axle friction braking force is increased slowly according to the first braking force distribution coefficient. The maximum energy recovery regenerative braking force is the dividing point between the initial stage of braking force request and the intermediate stage of braking force request. When the rear axle energy recovery regenerative braking force is increased to the maximum energy recovery regenerative braking force but still does not meet the total braking force requirement, it proves that the braking force needs to be increased further. However, at this time, the rear axle energy recovery regenerative braking module no longer needs to be increased. Therefore, the intervention of the front axle electromechanical braking module and the rear axle electromechanical braking module is required. During the process of increasing the braking force of the front axle and the rear axle, the rear axle energy recovery and regenerative braking force has already reached its maximum. Therefore, the increase in rear axle braking force is the rear axle friction braking force. The increase in front axle braking force and rear axle friction braking force is carried out according to the calculated first braking force distribution coefficient, ensuring that the front axle braking force is increased quickly and the rear axle friction braking force is increased slowly. The purpose of rapidly increasing the front axle braking force is to quickly increase the braking effect of the front axle, so as to match the braking of the rear axle (at this time, the rear axle braking force already has the basis of rear axle energy recovery and regenerative braking force). The purpose of increasing the rear axle friction braking force is to avoid the problem of poor vehicle stability and premature activation of ABS caused by the rear wheel slip rate due to the excessively rapid increase of the rear wheel friction braking force, which leads to the superposition of friction braking and regenerative braking.

[0025] In some embodiments of this application, the above-mentioned braking force distribution method has been optimized. Specifically, in step S1, it is also involved to determine the critical front axle braking force and the second braking force distribution coefficient based on the critical locking braking force of the front axle on a high-adhesion road surface (the high-adhesion road surface in this application is a well-adhesive high-adhesion asphalt road surface with an adhesion coefficient of 0.9~1.0).

[0026] Then, step S4 is also included, as follows: If the front axle braking force reaches the preset front axle braking force but still does not meet the total braking force requirement, then the front axle braking force and rear axle friction braking force are increased according to the second braking force distribution coefficient, until the front axle braking force approaches the critical front axle braking force, or the front axle braking force, rear axle friction braking force, and rear axle energy recovery feedback braking force meet the total braking force requirement. If the braking force is further increased while the front axle braking force is approaching the critical front axle braking force, it will trigger the ABS activation.

[0027] In this embodiment, the preset front axle braking force is another dividing point for the braking force request, which is the dividing point between the middle stage and the end stage of the braking force request. After the front axle braking force reaches the preset front axle braking force, if it is necessary to continue to increase the front axle braking force, it needs to be distributed according to the second braking force distribution coefficient. The purpose at this time is to increase the front axle braking force and the rear axle braking force to meet the driver's braking force target, maximize the vehicle's braking force, and delay the activation of ABS.

[0028] In a further embodiment of this application, the method of obtaining the first braking force distribution coefficient and the second braking force distribution coefficient described above has been optimized. Specifically, the first braking force distribution coefficient of this embodiment is determined based on the preset front axle braking force, the preset rear axle braking force, and the maximum energy recovery feedback braking force, while the preset front axle braking force and the preset rear axle braking force are obtained through calibration.

[0029] A calibration test is conducted on a road surface with a given coefficient of adhesion. The preset front axle braking force is the braking force required when both the front and rear axles lock simultaneously under no-load conditions. The preset rear axle braking force is the product of the rear axle locking force and a set threshold value; the set threshold value is less than 1. Essentially, this constructs a standard test. Since the vehicle in the standard test is unloaded, the resulting preset front axle braking force is smaller than the braking force required for locking under real-world driving conditions on the same road surface. Setting the preset front axle braking force in this way improves vehicle stability during subsequent driving.

[0030] The threshold value set in this embodiment is 90%~95%, which means that the preset rear axle braking force is less than the rear axle braking force when the vehicle locks up, leaving a margin and avoiding the problem of lock-up and instability caused by excessive preset rear axle braking force.

[0031] Furthermore, this embodiment also involves constructing a calibration test to obtain the critical front axle braking force and critical rear axle braking force. The critical lock-up braking forces of the front and rear axles on a high-adhesion road surface are defined as the critical front axle braking force and critical rear axle braking force. Compared to the calibration test for obtaining preset front axle braking force and preset rear axle braking force, the test conditions for obtaining the critical front axle braking force and critical rear axle braking force have changed. The adhesion coefficient of the test road surface is increased. Therefore, under the same conditions, the obtained critical front axle braking force and critical rear axle braking force are greater than the corresponding preset front axle braking force and preset rear axle braking force.

[0032] The first braking force distribution coefficient can be determined based on the preset front axle braking force, the preset rear axle braking force, and the maximum energy recovery braking force. Specifically, the difference between the preset rear axle braking force and the maximum energy recovery braking force is used as the calculated value of the rear axle friction braking force; the ratio of the preset front axle braking force to the sum of the preset front axle braking force and the rear axle friction braking force is used as the first braking force distribution coefficient. In fact, the starting point of the intermediate stage of braking force request in this embodiment is when the rear axle energy recovery braking force reaches the maximum energy recovery braking force, and the ending point is when the front axle braking force is increased to the preset front axle braking force and the rear axle braking force is increased to the preset rear axle braking force. In order to avoid a situation where one braking force exceeds the limit while the other has not reached the limit during the process of increasing the front axle braking force and the rear axle braking force, the first braking force distribution coefficient is determined based on the preset front axle braking force and the preset rear axle braking force. The first braking force distribution coefficient is actually the ratio of the front axle braking force to the total friction braking force, which includes the front axle braking force and the rear axle friction braking force. Typically, the preset front axle braking force is greater than the calculated rear axle friction braking force; that is, the first braking force distribution coefficient should be greater than 0.5, usually between 0.6 and 0.9. During the intermediate stage of braking force request, both the front axle braking force and the rear axle friction braking force increase from zero. However, the interval from zero to the preset front axle braking force is longer than the interval from zero to the calculated rear axle friction braking force. When increasing the front axle braking force and the rear axle friction braking force within the same timeframe, the rate and magnitude of increase in the front axle braking force are obviously greater, while the rate and magnitude of increase in the rear axle braking force are smaller.

[0033] The second braking force distribution coefficient can be determined based on the preset front axle braking force, preset rear axle braking force, critical front axle braking force, critical rear axle braking force, and maximum energy recovery feedback braking force. Specifically, the first difference between the critical front axle braking force and the preset front axle braking force is calculated, and the second difference between the critical rear axle braking force and the preset rear axle braking force is calculated. The ratio of the first difference to the sum of the first and second differences is used as the second braking force distribution coefficient.

[0034] The purpose of constructing the second braking force distribution coefficient is to ensure that, after the front axle braking force exceeds the preset front axle braking force, the front axle braking force and the rear axle braking force are synchronously controlled to approach the critical front axle braking force and the critical rear axle braking force, and this approach is synchronous. This ensures that the magnitude of the front axle braking force and the rear axle braking force approaching the critical front axle braking force and the critical rear axle braking force are consistent, so that the front axle braking force and the rear axle braking force can quickly meet the driver's target braking force requirements.

[0035] In a further embodiment of this application, the above-mentioned braking force distribution method is further optimized. In actual control, at the initial stage of braking force request, the rear axle energy recovery feedback braking force is gradually increased from zero to the maximum energy recovery feedback braking force or to the total braking force according to the set rising speed.

[0036] That is, in the initial stage of braking force request, the regenerative braking force of the rear axle is gradually increased until the required total braking force or the maximum regenerative braking force is reached, so that the regenerative braking force of the rear axle changes evenly, ensuring that the braking process of the vehicle under the regenerative braking force of the rear axle is smooth and stable, without jerking or other problems, thus improving the driving and riding experience.

[0037] In practice, the braking force distribution method of this application first obtains the required calibration data and conducts calibration tests on a road surface with a given adhesion coefficient. The preset front axle braking force is defined as the braking force of the front axle when both the front and rear axles lock simultaneously under no-load conditions, and the preset rear axle braking force is defined as the product of the rear axle braking force and a set threshold. The critical braking forces of the front and rear axles on high-adhesion road surfaces are defined as the critical front axle braking force and the critical rear axle braking force. The difference between the preset rear axle braking force and the maximum energy recovery braking force is used as the calculated value of the rear axle friction braking force. The ratio of the preset front axle braking force to the sum of the preset front axle braking force and the calculated rear axle friction braking force is used as the first braking force distribution coefficient. The first difference between the critical front axle braking force and the preset front axle braking force is calculated, and the second difference between the critical rear axle braking force and the preset rear axle braking force is calculated. The ratio of the first difference to the sum of the first and second differences is used as the second braking force distribution coefficient. When driving a real vehicle, after a braking request is issued, the total braking force of the vehicle is obtained based on the braking signal. In the initial stage of the braking force request, corresponding Figure 2 In the range of 0 to T1 (T1 corresponds to the time when the rear axle energy recovery braking force reaches the maximum energy recovery braking force), the rear axle energy recovery braking force is gradually increased from zero to the maximum energy recovery braking force or to the total braking force according to the set upward speed. In the middle stage of the braking force request, corresponding Figure 2In the T1~T2 section (T2 corresponds to the time when the front axle braking force reaches the preset front axle braking force), if the rear axle energy recovery feedback braking force is increased to the maximum energy recovery feedback braking force but still does not meet the total braking force requirement, then the front axle braking force is increased rapidly and the rear axle friction braking force is increased slowly according to the first braking force distribution coefficient. At the end of the braking force request, corresponding Figure 2 In the section after T2, if the front axle braking force reaches the preset front axle braking force but still does not meet the total braking force requirement, the front axle braking force and the rear axle friction braking force will be increased according to the second braking force distribution coefficient until the front axle braking force approaches the critical front axle braking force or the front axle braking force, the rear axle friction braking force and the rear axle energy recovery feedback braking force meet the total braking force requirement.

[0038] The braking force request in this application is divided into three stages. In actual application, not every braking force request process needs to go through three stages. If the total braking force corresponding to the braking signal is less than the maximum energy recovery feedback braking force, then only the operation of the rear axle energy recovery feedback module is needed to determine the braking demand. If the total braking force is greater than the maximum energy recovery feedback braking force, but not greater than the sum of the preset front axle braking force and the preset rear axle braking force, then it is necessary to control the operation of the rear axle energy recovery feedback module and the electromechanical braking modules of the front and rear axles, and it is necessary to go through the above-mentioned initial stage and intermediate stage of braking force request. If the total braking force is greater than the sum of the preset front axle braking force and the preset rear axle braking force, then it is necessary to go through the above-mentioned three stages.

[0039] This application also relates to a braking force distribution control system. The control method operates according to the aforementioned braking force distribution control method, including a brake request identification module, a maximum regenerative braking force determination module, a preset front axle braking force determination module, a first braking distribution coefficient determination module, a first adjustment module, and a second adjustment module. The brake request identification module is used to identify whether a braking request exists and obtain the total braking force of the vehicle based on the braking signal after the braking request occurs. The maximum regenerative braking force determination module is used to determine the maximum allowable energy recovery braking force of the rear axle. The preset front axle braking force determination module determines the preset front axle braking force based on the critical lock-up braking force of the front axle on a road surface with a given adhesion coefficient. The first braking distribution coefficient determination module determines a first braking force distribution coefficient based on the preset front axle braking force. The first adjustment module is used to control the rear axle energy recovery braking force as the only braking force in the initial stage of the braking force request and gradually increase the rear axle energy recovery braking force. The second adjustment module is used to rapidly increase the front axle braking force and slowly increase the rear axle friction braking force according to the first braking force distribution coefficient when the rear axle energy recovery braking force is increased to the maximum energy recovery braking force but still does not meet the total braking force requirement.

[0040] It also includes a critical front axle braking force determination module, a second braking distribution coefficient determination module, and a third adjustment module. The critical front axle braking force determination module is used to determine the critical front axle braking force based on the critical lock-up braking force of the front axle on a high-adhesion road surface. The second braking distribution coefficient determination module determines the second braking force distribution coefficient based on the critical front axle braking force. The third adjustment module is used to increase the front axle braking force and the rear axle friction braking force according to the second braking force distribution coefficient when the front axle braking force reaches the preset front axle braking force but still does not meet the total braking force requirement, so that the front axle braking force infinitely approaches the critical front axle braking force or the front axle braking force, the rear axle friction braking force, and the rear axle energy recovery feedback braking force meet the total braking force requirement.

[0041] 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 a braking force distribution control method in the above embodiments.

[0042] 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.

[0043] The aforementioned computer-readable storage medium may be included in the range-extended electric vehicle control device; or it may exist independently and not assembled into the range-extended electric vehicle control device.

[0044] The aforementioned computer-readable storage medium carries one or more programs. When these programs are executed by a brake force distribution control system, after a braking request occurs, the system obtains the total braking force of the vehicle based on the braking signal; determines the maximum allowable energy recovery regenerative braking force of the rear axle; determines a preset front axle braking force based on the critical lock-up braking force of the front axle on a road surface with a given coefficient of adhesion, and determines a first braking force distribution coefficient; in the initial stage of the braking force request, the system controls the rear axle energy recovery regenerative braking force as the sole braking force, and gradually increases the rear axle energy recovery regenerative braking force; if the rear axle energy recovery regenerative braking force, even when increased to the maximum energy recovery regenerative braking force, still does not meet the total braking force requirement, then the system rapidly increases the front axle braking force and slowly increases the rear axle friction braking force according to the first braking force distribution coefficient.

[0045] 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.

[0046] 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).

[0047] 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.

[0048] 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.

[0049] 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 range-extended electric vehicle 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 the beneficial effects of the braking force distribution control method provided in the above embodiments, and will not be repeated here.

[0050] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the braking force distribution control method described above.

[0051] 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 the beneficial effects of the braking force distribution control method provided in the above embodiments, and will not be repeated here.

[0052] 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 braking force distribution control method, characterized in that: include, After a braking request is issued, the total braking force of the vehicle is obtained based on the braking signal. Determine the maximum permissible energy recovery braking force on the rear axle; The preset front axle braking force is determined based on the critical locking braking force of the front axle on a road surface with a given adhesion coefficient, and the first braking force distribution coefficient is determined. In the initial stage of braking force request, the rear axle energy recovery feedback braking force is controlled as the only braking force, and the rear axle energy recovery feedback braking force is gradually increased. If the maximum energy recovery braking force of the rear axle is still insufficient to meet the total braking force requirement, then the front axle braking force will be rapidly increased and the rear axle friction braking force will be slowly increased according to the first braking force distribution coefficient.

2. The braking force distribution control method as described in claim 1, characterized in that: The critical front axle braking force is determined based on the critical locking braking force of the front axle on a high-adhesion road surface, and the second braking force distribution coefficient is determined accordingly. If the front axle braking force reaches the preset front axle braking force but still does not meet the total braking force requirement, then the front axle braking force and the rear axle friction braking force are increased according to the second braking force distribution coefficient.

3. The braking force distribution control method as described in claim 2, characterized in that: A calibration test is conducted on a road surface with a given adhesion coefficient. The front axle locking braking force when both the front and rear axles lock simultaneously under no-load conditions is taken as the preset front axle braking force, and the product of the rear axle locking braking force and a set threshold is taken as the preset rear axle braking force; the set threshold is less than 1.

4. The braking force distribution control method as described in claim 3, characterized in that: The method for determining the first braking force distribution coefficient includes: using the difference between the preset rear axle braking force and the maximum energy recovery braking force as the calculated value of the rear axle friction braking force; and using the ratio of the preset front axle braking force to the sum of the preset front axle braking force and the calculated value of the rear axle friction braking force as the first braking force distribution coefficient.

5. The braking force distribution control method as described in claim 4, characterized in that: The method for determining the second braking force distribution coefficient includes: using the critical locking braking forces of the front axle and rear axle on a high-adhesion road surface as the critical front axle braking force and the critical rear axle braking force; calculating a first difference between the critical front axle braking force and the preset front axle braking force; calculating a second difference between the critical rear axle braking force and the preset rear axle braking force; and using the ratio of the first difference to the sum of the first difference and the second difference as the second braking force distribution coefficient.

6. The braking force distribution control method as described in claim 1, characterized in that: The method for gradually increasing the rear axle energy recovery braking force includes: gradually increasing the rear axle energy recovery braking force from zero to the maximum energy recovery braking force or to the total braking force according to a set upward speed.

7. A braking force distribution control system, characterized in that: The control method is operated according to any one of the braking force distribution control methods described in claims 1 to 6. include, A braking request identification module is used to identify whether a braking request exists, and to obtain the total braking force of the vehicle based on the braking signal after the braking request occurs. A maximum regenerative braking force determination module is used to determine the maximum allowable energy recovery braking force of the rear axle. A preset front axle braking force determination module determines the preset front axle braking force based on the critical lock-up braking force of the front axle on a road surface with a given adhesion coefficient. The first braking distribution coefficient determination module determines the first braking force distribution coefficient based on a preset front axle braking force. The first adjustment module is used to control the rear axle energy recovery feedback braking force as the only braking force in the initial stage of braking force request, and gradually increase the rear axle energy recovery feedback braking force. The second adjustment module is used to rapidly increase the front axle braking force and slowly increase the rear axle friction braking force according to the first braking force distribution coefficient when the rear axle energy recovery feedback braking force is increased to the maximum energy recovery feedback braking force but still does not meet the total braking force requirement.

8. The braking force distribution control system as described in claim 7, characterized in that: It also includes, A critical front axle braking force determination module is used to determine the critical front axle braking force based on the critical lock-up braking force of the front axle on a high-adhesion road surface. The second braking distribution coefficient determination module determines the second braking force distribution coefficient based on the critical front axle braking force. The third adjustment module is used to increase the front axle braking force and the rear axle friction braking force according to the second braking force distribution coefficient when the front axle braking force reaches the preset front axle braking force but still does not meet the total braking force requirement.

9. 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 braking force distribution control method as described in any one of claims 1 to 6.

10. 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 braking force distribution control method as described in any one of claims 1 to 6.

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