ABS master cylinder pressure self-learning correction method
By calculating the master cylinder pressure correction coefficient using ambient temperature and brake temperature rise in the ABS system, the problem of inaccurate master cylinder pressure estimation in the ABS system is solved, achieving accurate estimation of master cylinder pressure and improving vehicle smoothness and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI QIANGU AUTOMOBILE TECH CO LTD
- Filing Date
- 2026-01-26
- Publication Date
- 2026-04-14
AI Technical Summary
In existing automotive ABS systems, the lack of a master cylinder pressure sensor leads to inaccurate estimation of master cylinder pressure when brake temperature changes, causing vehicle vibration and deceleration loss, which affects driving safety.
By acquiring the ambient temperature as the initial brake temperature and combining it with the temperature rise during the braking process to calculate the master cylinder pressure correction coefficient, the corrected master cylinder pressure value is calculated using a preset formula, thereby achieving accurate estimation of the master cylinder pressure and avoiding the need for additional hardware sensors.
It effectively solves the problem of inaccurate master cylinder pressure estimation caused by temperature changes, improves the smoothness of ABS control and deceleration loss, and enhances driving safety.
Smart Images
Figure CN121849110A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of automotive braking technology, specifically relating to a self-learning correction method for ABS master cylinder pressure. Background Technology
[0002] Current automotive ABS (Anti-lock Braking System) products do not have a master cylinder pressure sensor. Their anti-lock control relies on the estimated value of the master cylinder pressure. When excessive braking force causes the wheels to lock up, the anti-lock function of the ABS product is activated to control the lock-up. However, when frequent braking causes a rapid change in brake temperature, the braking distance will increase significantly at the same braking pressure and vehicle speed.
[0003] Similarly, changes in brake temperature can lead to errors in master cylinder pressure estimation, which in turn causes the ABS wheel-end pressure control to become inaccurate. Since the wheel-end control relies on master cylinder pressure, this can cause problems such as vehicle vibration and deceleration loss, affecting driving safety.
[0004] Therefore, in order to solve the problems of poor vehicle ride comfort and deceleration loss caused by inaccurate wheel-end master cylinder pressure, it is urgent to develop an ABS master cylinder pressure self-learning correction method. Summary of the Invention
[0005] The purpose of this invention is to propose a self-learning correction method for ABS master cylinder pressure to solve the problems in the prior art.
[0006] Therefore, the present invention provides a self-learning correction method for ABS master cylinder pressure, comprising: Obtain the ambient temperature and use it as the initial temperature value of the brake. Determine whether the brake is in a braking state under the current conditions; When the brake is in the braking state, the temperature rise value of the brake is obtained, and the current temperature value of the brake is obtained based on the initial brake temperature value and the temperature rise value; The initial value of the master cylinder pressure and the master cylinder pressure correction coefficient are obtained, and the corrected master cylinder pressure value is calculated based on a preset formula.
[0007] In some embodiments, obtaining the temperature rise value of the brake includes: Obtain the current braking torque traction force, braking surface area, and brake disc specific heat capacity; The temperature rise of the brake was calculated based on the formula.
[0008] In some embodiments, the formula for calculating the temperature rise is:
[0009] Where B is the temperature rise value; M is the unloaded mass; a is the deceleration; r is the wheel rolling radius; CP represents the relationship between the brake pressure and the braking torque. C is the specific heat capacity of the brake disc; A represents the area of the friction plate; λ is the thermal conductivity of the brake disc; N is the interpolation coefficient, which is calculated by looking up a table using the current vehicle deceleration.
[0010] In some embodiments, obtaining the master cylinder pressure correction coefficient includes: The pressure correction coefficient is obtained in real time by looking up a table based on the current brake temperature and using linear interpolation within different brake temperature ranges.
[0011] In some embodiments, obtaining the initial pressure value includes: Obtain the vehicle's unloaded mass, wheel rolling radius, vehicle deceleration, and CP value; The initial pressure value is calculated based on the formula.
[0012] In some embodiments, the formula for calculating the initial pressure value is:
[0013] Where H is the initial pressure value; M is the unloaded mass; a is the deceleration; r is the wheel rolling radius; CP represents the relationship between the braking pressure and braking torque of the brake.
[0014] In some embodiments, the formula for calculating the modified master cylinder pressure value is as follows:
[0015] Where F is the corrected master cylinder pressure value; H is the initial value for the main cylinder; D is the main cylinder pressure correction coefficient.
[0016] In some embodiments, it also includes: The required fluid volume at the wheel end under the current condition is calculated based on the master cylinder pressure value.
[0017] In some embodiments, calculating the required hydraulic fluid at the wheel end under the current state based on the master cylinder pressure value includes: Obtain the pipeline stiffness coefficient, valve orifice Bernoulli coefficient, and master cylinder pressure value; The required liquid volume for the pressure is calculated using the formula.
[0018] In some embodiments, the formula for calculating the pressure liquid requirement is:
[0019] Where V is the liquid required for the wheel end pressure; F represents the corrected master cylinder pressure value; C is the pipeline structure correction factor; μ is the Bernoulli coefficient for the valve orifice.
[0020] Beneficial effects: This invention introduces brake temperature self-learning into ABS, using ambient temperature as the initial brake temperature and calculating the brake temperature rise during braking to obtain the current brake temperature. Based on the current deceleration and the brake temperature value, a master cylinder pressure correction coefficient is calculated. Then, combined with the initial master cylinder pressure value, a corrected master cylinder pressure estimate is calculated and participated in the ABS control calculation. This solves the problem that in existing ABS systems without a master cylinder pressure sensor, brake temperature changes lead to inaccurate master cylinder pressure estimation, which in turn causes inaccurate ABS control, uneven vehicle ride, and deceleration loss. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Fig. 1 This is a flowchart illustrating the ABS master cylinder pressure self-learning correction method provided by the present invention.
[0023] Fig. 2 This is a flowchart illustrating the ABS master cylinder pressure self-learning correction method provided by the present invention. Detailed Implementation
[0024] The invention will be more readily understood by referring to the following detailed description of preferred embodiments and included examples. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the definitions in this specification shall prevail.
[0025] This invention provides a self-learning correction method for ABS master cylinder pressure, which solves the problem in the prior art where the calculation of master cylinder pressure value is biased, resulting in errors in the calculation of wheel end pressure fluid requirement, which leads to reduced vehicle ride comfort and deceleration loss during braking, and even safety hazards.
[0026] The technical concept of this invention is to use the ambient temperature value as the initial temperature value of the brake. During the braking process, the temperature value after the rise is obtained and combined with the deceleration to calculate the master cylinder pressure correction coefficient. By combining the master cylinder pressure correction coefficient with the initial master cylinder pressure value, a more accurate master cylinder pressure value is estimated after correction, thereby ensuring the accurate supply of hydraulic pressure at the wheel end during braking, ensuring the smoothness of the vehicle body under braking conditions and preventing deceleration loss.
[0027] Meanwhile, this application is a correction method during vehicle operation, rather than a formal condition under non-formal working conditions such as laboratory work. Therefore, the difficulty lies in the fact that obtaining the brake temperature is relatively simple and convenient for the laboratory, which can generally be obtained directly by using a temperature sensor, such as an infrared temperature sensor. However, for a vehicle in normal working condition, it is impractical to set up temperature sensors around the brake. This application uses the ambient temperature as the initial temperature and combines it with the temperature rise value of the vehicle's brake disc during braking to calculate the current temperature value of the brake, which can effectively correct the master cylinder pressure value without the need for additional hardware such as temperature sensors.
[0028] like Figs. 1-2 As shown, an ABS master cylinder pressure self-learning correction method includes: The ambient temperature is acquired and used as the initial brake temperature value. It should be noted that the initial brake temperature value refers to the temperature of the brake when it is not in use and is in its initial static state. Since the brake does not generate heat due to friction in the initial state, its temperature is the same as the ambient temperature around the vehicle. Therefore, the ambient temperature is directly used as this initial value, eliminating the need for an additional sensor specifically for acquiring the initial brake temperature. Data acquisition can be achieved using the vehicle's existing ambient temperature sensor, reducing hardware costs and system complexity.
[0029] To determine whether the brakes are in a braking state under the current conditions, specifically, the braking state refers to the state in which the vehicle's braking system is activated and the brakes begin to generate braking force. This is usually determined by the vehicle's brake pedal signal, changes in brake line pressure, or trends in wheel speed. For example, when the brake pedal is depressed, the master cylinder supplies brake fluid to the brake lines, and the brakes come into contact with the brake discs / drums, generating friction. This is when the braking state is determined.
[0030] When the brake is in braking condition, the temperature rise value of the brake is acquired, and the current temperature value of the brake is obtained based on the initial brake temperature value and the temperature rise value. By capturing the thermal state changes of the brake in real time and dynamically during braking, this method overcomes the limitation of traditional methods that ignore temperature changes. Furthermore, the current temperature value obtained by superimposing the initial temperature and the temperature rise value can accurately reflect the actual impact of the brake on the braking pressure, providing crucial and accurate parameter support for the subsequent calculation of the master cylinder pressure correction coefficient, and avoiding deviations caused by temperature parameter distortion.
[0031] The initial value of the master cylinder pressure and the master cylinder pressure correction coefficient are obtained, and the corrected master cylinder pressure value is calculated based on a preset formula.
[0032] The master cylinder pressure correction coefficient, by combining the current temperature and deceleration, can specifically counteract the interference of temperature on pressure estimation. The resulting corrected master cylinder pressure value effectively solves the problem of inaccurate master cylinder pressure estimation caused by temperature changes when existing ABS systems lack a master cylinder pressure sensor. This provides a precise pressure reference for subsequent wheel-end pressure control by the ABS, thereby improving ABS control smoothness and reducing deceleration loss.
[0033] In one embodiment, obtaining the temperature rise value of the brake includes: Obtain the current braking torque traction force, braking surface area, and brake disc specific heat capacity. The braking torque traction force is a parameter related to the torque that drives the brake to generate braking force during braking. The braking surface area is the effective area of contact friction between the brake and the brake disc. The brake specific heat capacity is the amount of heat required for a unit mass of brake disc material to increase its temperature by a unit, and is an inherent parameter in the brake design.
[0034] The temperature rise of the brake was calculated based on the formula.
[0035] The specific calculation formula is as follows:
[0036] Where B is the temperature rise value; M is the unloaded mass; a is the deceleration; r is the wheel rolling radius; CP represents the relationship between the brake pressure and the braking torque. C is the specific heat capacity of the brake disc; A represents the area of the friction plate; λ is the thermal conductivity of the brake disc; N is the interpolation coefficient. N is calculated by looking up a table based on the current vehicle deceleration. The value is obtained in real time using linear interpolation within different vehicle deceleration ranges, which is N.
[0037] By combining the above parameters, the temperature rise at the moment of braking can be calculated. This allows the temperature increase to be obtained without the need for an additional temperature sensor, based on the ambient temperature as the initial temperature of the brake. This facilitates the subsequent calculation of the current brake temperature.
[0038] In one embodiment, obtaining the master cylinder pressure correction coefficient includes: The value is calculated by referring to a table based on the current brake temperature, and then obtained in real time using linear interpolation within different brake temperature ranges. This value is the master cylinder pressure correction coefficient D.
[0039] By calculating the master cylinder pressure correction coefficient, the interference of brake temperature on the master cylinder pressure estimation can be offset. This allows for subsequent calibration based on the initial master cylinder pressure value to obtain the true master cylinder pressure value after the temperature rises following braking, thus facilitating subsequent wheel end fluid supply.
[0040] In one embodiment, obtaining the initial pressure value includes: Obtain the vehicle's unloaded mass, wheel rolling radius, vehicle deceleration, and CP value; Among them, vehicle unloaded mass refers to the mass of the vehicle itself when it is not carrying passengers, cargo and additional load. This parameter is an inherent attribute determined during the design and production of the vehicle and can be obtained directly from the technical documents provided by the vehicle manufacturer without the need for additional measurement.
[0041] The wheel rolling radius refers to the vertical distance from the wheel's center axis to the point of contact between the tire and the ground. It reflects the basic geometric dimensions of the wheel when it rolls. It is calculated based on the vehicle's wheel hub and tire specifications, or can be directly found in the vehicle's manufacturer's technical manual. It is an inherent parameter of the vehicle.
[0042] CP is the relationship coefficient between braking pressure and braking torque of a brake system. It reflects the corresponding ratio of braking pressure to braking torque in the braking system. It is determined by the design parameters of the vehicle's brakes. This parameter is an inherent property that is fixed during the production of the brakes and directly determines the conversion efficiency of braking pressure and braking torque.
[0043] The initial pressure value is calculated based on the formula.
[0044] The formula for calculating the initial pressure value is as follows:
[0045] Where H is the initial pressure value; M is the unloaded mass; a is the deceleration; r is the wheel rolling radius; CP represents the relationship between the braking pressure and braking torque of the brake.
[0046] The vehicle's unloaded mass M, wheel rolling radius r, and CP value required to calculate the initial pressure value are all inherent parameters of the vehicle and brakes, which can be obtained directly from the manufacturer's technical documents or supplier information. The deceleration can be obtained directly from the vehicle system without the need for additional sensors or complex measurements, thus reducing the cost and difficulty of parameter acquisition.
[0047] In one embodiment, the modified formula for calculating the master cylinder pressure value is:
[0048] Where F is the corrected master cylinder pressure value; H is the initial value for the main cylinder; D is the master cylinder pressure correction coefficient. By combining the initial master cylinder pressure value with the correction coefficient, the master cylinder pressure value at the moment of braking can be accurately reflected, thus facilitating the subsequent accurate calculation of the actual wheel end pressure required by the fluid.
[0049] In one embodiment, it also includes: The required hydraulic fluid volume at the wheel end under the current condition is calculated based on the master cylinder pressure value. Specifically, the pipeline rigidity coefficient, valve orifice Bernoulli coefficient, and master cylinder pressure value are obtained. The required liquid volume for the pressure is calculated using the formula.
[0050] The calculation formula is:
[0051] Where V is the liquid required for the wheel end pressure; F represents the corrected master cylinder pressure value; C is the pipeline structure correction factor, which is an inherent parameter of the pipeline; μ is the Bernoulli coefficient of the valve orifice, which is an inherent parameter of the solenoid valve.
[0052] Specifically, the calculated wheel-end pressure and required amount of brake fluid are directly used as the control input for the ABS solenoid valve. The controller can adjust the opening and closing time and opening degree of the solenoid valve according to the V value to ensure that the brake fluid is accurately delivered to the wheel end, avoiding insufficient braking force due to insufficient fluid or wheel lock-up due to excessive fluid, thereby improving the vehicle's braking smoothness and safety.
[0053] In one embodiment, a vehicle equipped with the ABS product of this method is driven on a dry asphalt road surface at an initial speed of 100 km / h. The brake pedal is rapidly depressed until the wheels lock up, and this experiment is repeated 8 times continuously while maintaining a constant pedal position. Throughout the process, the vehicle ride is relatively smooth, and the deceleration loss slows down after a rapid rise in brake disc temperature, resulting in good vehicle ride comfort. When driving a vehicle without the ABS product of this method under the same conditions on dry asphalt, a rapid rise in brake disc temperature and severe deceleration loss are observed, and the anti-lock braking function is activated, resulting in poor vehicle ride comfort.
[0054] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A self-learning correction method for ABS master cylinder pressure, characterized in that, include: Obtain the ambient temperature and use it as the initial temperature value of the brake. Determine whether the brake is in a braking state under the current conditions; When the brake is in the braking state, the temperature rise value of the brake is obtained, and the current temperature value of the brake is obtained based on the initial brake temperature value and the temperature rise value; The initial value of the master cylinder pressure and the master cylinder pressure correction coefficient are obtained, and the corrected master cylinder pressure value is calculated based on a preset formula.
2. The ABS master cylinder pressure self-learning correction method according to claim 1, characterized in that, Obtaining the temperature rise value of the brake includes: Obtain the current braking torque traction force, braking surface area, and brake disc specific heat capacity; The temperature rise of the brake was calculated based on the formula.
3. The ABS master cylinder pressure self-learning correction method according to claim 2, characterized in that, The formula for calculating the temperature rise is: Where B is the temperature rise value; M is the unloaded mass; a is the deceleration; r is the wheel rolling radius; CP represents the relationship between the brake pressure and the braking torque. C is the specific heat capacity of the brake disc; A represents the area of the friction plate; λ is the thermal conductivity of the brake disc; N is the interpolation coefficient, which is calculated by looking up a table using the current vehicle deceleration.
4. The ABS master cylinder pressure self-learning correction method according to claim 1, characterized in that, The method for obtaining the master cylinder pressure correction coefficient includes: The pressure correction coefficient is obtained in real time by looking up a table based on the current brake temperature and using linear interpolation within different brake temperature ranges.
5. The ABS master cylinder pressure self-learning correction method according to claim 1, characterized in that, The acquisition of the initial pressure value includes: Obtain the vehicle's unloaded mass, wheel rolling radius, vehicle deceleration, and CP value; The initial pressure value is calculated based on the formula.
6. The ABS master cylinder pressure self-learning correction method according to claim 5, characterized in that, The formula for calculating the initial pressure value is: Where H is the initial pressure value; M is the unloaded mass; a is the deceleration; CP represents the relationship between the braking pressure and braking torque of the brake.
7. The ABS master cylinder pressure self-learning correction method according to claim 1, characterized in that, The revised formula for calculating the master cylinder pressure value is as follows: Where F is the corrected master cylinder pressure value; H is the initial value for the main cylinder; r is the wheel rolling radius; D is the main cylinder pressure correction coefficient.
8. The ABS master cylinder pressure self-learning correction method according to claim 1, characterized in that, Also includes: The required fluid volume at the wheel end under the current condition is calculated based on the master cylinder pressure value.
9. The ABS master cylinder pressure self-learning correction method according to claim 8, characterized in that, The calculation of the required fluid volume at the wheel end under the current state based on the master cylinder pressure value includes: Obtain the pipeline stiffness coefficient, valve orifice Bernoulli coefficient, and master cylinder pressure value; The required liquid volume for the pressure is calculated using the formula.
10. The ABS master cylinder pressure self-learning correction method according to claim 9, characterized in that, The formula for calculating the pressure liquid requirement is: Where V is the liquid required for the wheel end pressure; F represents the corrected master cylinder pressure value; C is the pipeline structure correction factor; μ is the Bernoulli coefficient for the valve orifice.