Brake pressure control method and control module

Abstract

The invention discloses a brake pressure control method and a control module, the brake pressure control method is used for an electronic power-assisted brake system, and the brake pressure control method comprises the following steps: judging whether to trigger pressure control according to a brake anti-lock function working state and target pressure, if so, executing brake pressure control, and if not, executing brake pressure control; otherwise, the electronic power-assisted braking system provides braking force according to the normal driving working condition; according to the braking intention demand, the vehicle speed demand, the maximum wheel cylinder pressure demand and the actual main cylinder pressure demand, the target main cylinder piston thrust is obtained through calculation; actual piston thrust is calculated according to the main cylinder pressure signal state, the actual main cylinder pressure and the conversion coefficient from the main cylinder pressure to the piston thrust; and the rotating speed of the motor is adjusted according to the target main cylinder piston thrust and the actual piston thrust. The brake pressure can be actively adjusted through the motor between the target main cylinder piston thrust and the actual piston thrust, so that the brake pressure meets the brake requirement, and damage and safety defects caused by too high or too low brake pressure can be avoided.

Description

Technical Field

[0001] The present invention relates to the field of automobiles, and in particular to a brake pressure control method and a control module.

[0002] View Technology

[0003] Electro-Hydraulic Brake System (EHB) is an important development direction of automobile braking system. It combines the advantages of electronic control and hydraulic transmission to provide more efficient and precise braking performance. The main feature of the electronic hydraulic brake system (EHB) is that it uses electronic components to replace some mechanical parts in the traditional brake system, while retaining the original mature and reliable hydraulic part. This system has outstanding advantages such as compact structure, fast response, easy to achieve regenerative braking, precise control of braking force, and easy to achieve a variety of active safety control functions.

[0004] The core of the EHB system is the electronic control unit (ECU), which receives a variety of data from sensors, including vehicle speed, brake pedal force, tire status, etc., and analyzes and makes corresponding braking decisions in real time. The ECU's intelligent algorithm enables the EHB system to adjust the braking force according to the actual driving conditions to achieve a more precise and efficient braking effect. The system is equipped with an electric pump unit, whose main task is to provide additional force when the brake hydraulic pressure needs to be increased. This electric assistance can respond to braking needs in an instant, making the braking process more flexible and rapid.

[0005] Since the electronic hydraulic brake system that uses the motor to drive the deceleration mechanism to push the master cylinder to build pressure replaces the vacuum booster of traditional cars, it still needs to be used in conjunction with the anti-lock braking system ABS or the electronic stability control system ESC module. Therefore, it involves the problem of coordinating with the ABS when the ABS function is triggered. When the ABS is triggered, the ABS motor pump will pump fluid into the master cylinder, causing the master cylinder fluid to increase and the brake system pressure to be too high. In order to protect the normal operation of the ABS\ESC system, the electronic hydraulic brake system needs to properly adjust the system pressure while ensuring the normal operation of the ABS\ESC to avoid brake lock that affects safety. Summary of the invention

[0006] A series of simplified concepts are introduced in the Summary of the Invention, which are all simplifications of the prior art in the field, and will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention of the present invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0007] The technical problem to be solved by the present invention is to provide a brake pressure control method and a control module which can actively adjust the brake system pressure and avoid brake locking under the premise of ensuring the normal operation of ABS\ESC.

[0008] In order to solve the above technical problems, the present invention provides a brake pressure control method, which is used in an electronic power-assisted brake system and includes the following steps:

[0009] S1, determine whether to trigger the pressure control according to the working state of the anti-lock braking function and the target pressure. If triggered, execute step S2, otherwise the electronic power-assisted braking system provides braking force according to normal driving conditions;

[0010] S2, brake master cylinder pressure build-up, calculate the target master cylinder piston thrust according to the braking intention requirement, vehicle speed requirement, maximum wheel cylinder pressure requirement and actual master cylinder pressure requirement;

[0011] S3, calculating the actual thrust, calculating the actual piston thrust according to the master cylinder pressure signal state, the actual master cylinder pressure and the master cylinder pressure to piston thrust conversion coefficient;

[0012] S4, adjusts the motor speed according to the target master cylinder piston thrust and the actual piston thrust, thereby controlling the master cylinder pressure to prevent anti-lock.

[0013] Preferably, the brake pressure control method is further improved, and when step S1 is implemented, it includes:

[0014] If the anti-lock braking function is triggered, the anti-lock braking function has not failed, and the target hydraulic pressure is greater than 1 bar, the pressure control is triggered, otherwise the electronic power-assisted braking system provides braking force according to normal driving conditions.

[0015] Preferably, the brake pressure control method is further improved, and when step S2 is implemented, it includes:

[0016] The braking intention requirement is calculated using the following formula (1):

[0017] P t arg =P t arg 1 +P off (1)

[0018] P t arg is the hydraulic pressure required for the braking intention after processing, P t arg 1 is the driver demand pressure, P off is the brake intention hydraulic pressure offset;

[0019] The vehicle speed requirement is calculated using the following formula (2):

[0020] P vehs =K v (Pmax -P min ) (2);

[0021] P vehs K is the hydraulic pressure required by vehicle speed, v is the vehicle speed coefficient, P max , P min are the maximum and minimum support pressures respectively;

[0022] The maximum wheel cylinder pressure requirement is calculated using the following formula (3):

[0023] P whlt arg =P whl max +P off1 +P off2 (3)

[0024] P whlt arg is the master cylinder hydraulic pressure required for the maximum wheel cylinder pressure, P whl max is the maximum wheel cylinder pressure, P off1 , P off2 The hydraulic pressure offset added to prevent the pressure from fluctuating below the required value;

[0025] The required master cylinder hydraulic pressure is calculated using the following formula (4):

[0026] P t arg all =min(P t arg ,P vehs ,P whlt arg )-P deoff (4)

[0027] P t arg all is the required master cylinder hydraulic pressure, P deoff The pressure value that needs to be reduced is obtained based on the actual master cylinder pressure;

[0028] The required master cylinder hydraulic pressure is calculated by using the following formula (5):

[0029] F t arg =P t arg all β (5)

[0030] F t arg is the target master cylinder piston thrust, and β is the cylinder pressure to thrust conversion coefficient.

[0031] Preferably, the brake pressure control method is further improved, and when step S3 is implemented, it includes:

[0032] There is a master cylinder pressure signal, and the actual piston thrust is calculated using the following formula (6);

[0033] F a =P a β (6)

[0034] F a is the actual thrust calculated, P a is the actual master cylinder pressure, β is the hydraulic pressure to thrust conversion coefficient;

[0035] In the absence of a master cylinder pressure signal, the actual piston thrust is calculated using the following formula (7):

[0036] F a =T a ·v·α-F g (7)

[0037] T a is the motor output torque, v is the motor speed, α is the torque-thrust conversion coefficient, F g It is the inertial force.

[0038] Preferably, the brake pressure control method is further improved, and when step S4 is implemented, it includes:

[0039] The thrust deviation F is calculated using the following formula (8): err ;

[0040] F err =F targ -F a (8)

[0041] x is the dead zone threshold, V max ,V min They are the speed output given values ​​in the forward and reverse dead zones respectively;

[0042] If |F err |>x, then V targ =K P -F err ;

[0043] If |F err |<x, and |F err |<0, then V targ =V min ;

[0044] If |F err |<x, and |F err |>0, then V targ =V max ;

[0045] V t arg is the motor target speed, K P is the proportional control coefficient.

[0046] In order to solve the above technical problems, the present invention provides a brake pressure control module, which is used in an electronic power-assisted brake system, comprising:

[0047] A judgment unit, which judges whether to trigger the brake pressure control module according to the working state of the anti-lock braking function of the electronic power-assisted braking system and the target pressure. If not, the electronic power-assisted braking system provides braking force according to the normal driving condition;

[0048] A brake master cylinder pressure control unit calculates a target master cylinder piston thrust according to a braking intention requirement, a vehicle speed requirement, a maximum wheel cylinder pressure requirement, and an actual master cylinder pressure requirement;

[0049] an actual thrust calculation unit, which calculates the actual piston thrust according to the master cylinder pressure signal state, the actual master cylinder pressure and the master cylinder pressure to piston thrust conversion coefficient;

[0050] The motor speed control unit adjusts the motor speed according to the target master cylinder piston thrust and the actual piston thrust, thereby controlling the master cylinder pressure to prevent anti-lock.

[0051] Preferably, the brake pressure control module is further improved, and the judgment condition of the judgment unit includes:

[0052] If the anti-lock braking function is triggered, the anti-lock braking function has not failed, and the target hydraulic pressure is greater than 1 bar, the pressure control is triggered, otherwise the electronic power-assisted braking system provides braking force according to normal driving conditions.

[0053] Preferably, the brake pressure control module is further improved, and the brake master cylinder pressure control unit calculates the target master cylinder piston thrust including:

[0054] The braking intention requirement is calculated using the following formula (1):

[0055] P t arg =P t arg 1 +P off (1)

[0056] P t arg is the hydraulic pressure required for the braking intention after processing, P t arg 1 is the driver demand pressure, P off is the brake intention hydraulic pressure offset;

[0057] The vehicle speed requirement is calculated using the following formula (2):

[0058] P vehs =K v (P max -P min ) (2);

[0059] P vehs K is the hydraulic pressure required by vehicle speed, v is the vehicle speed coefficient, P max , P minare the maximum and minimum support pressures respectively;

[0060] The maximum wheel cylinder pressure requirement is calculated using the following formula (3):

[0061] P whlt arg =P whl max +P off1 +P off2 (3)

[0062] P whlt arg is the master cylinder hydraulic pressure required for the maximum wheel cylinder pressure, P whl max is the maximum wheel cylinder pressure, P off1 , P off2 The hydraulic pressure offset added to prevent the pressure from fluctuating below the required value;

[0063] The required master cylinder hydraulic pressure is calculated using the following formula (4):

[0064] P t arg all =min(P t arg ,P vehs ,P whlt arg )-P deoff (4)

[0065] P t arg all is the required master cylinder hydraulic pressure, P deoff The pressure value that needs to be reduced is obtained based on the actual master cylinder pressure;

[0066] The required master cylinder hydraulic pressure is calculated by using the following formula (5):

[0067] F t arg =P t arg all β (5)

[0068] F t arg is the target master cylinder piston thrust, and β is the cylinder pressure to thrust conversion coefficient.

[0069] Preferably, the brake pressure control module is further improved, and the actual thrust calculation unit calculates the actual piston thrust including:

[0070] There is a master cylinder pressure signal, and the actual piston thrust is calculated using the following formula (6);

[0071] F a =P a β (6)

[0072] F a is the actual thrust calculated, P a is the actual master cylinder pressure, β is the hydraulic pressure to thrust conversion coefficient;

[0073] In the absence of a master cylinder pressure signal, the actual piston thrust is calculated using the following formula (7):

[0074] F a =T a ·v·α-F g (7)

[0075] T a is the motor output torque, v is the motor speed, α is the torque-thrust conversion coefficient, F g It is the inertial force.

[0076] Preferably, the brake pressure control module is further improved, and the motor speed control unit adjusts the motor speed including:

[0077] The thrust deviation F is calculated using the following formula (8): err ;

[0078] F err =F t arg -F a (8)

[0079] x is the dead zone threshold, V max ,V min They are the speed output given values ​​in the forward and reverse dead zones respectively;

[0080] If |F err |>x, then V t arg =K P -F err ;

[0081] If |F err |<x, and |F err |<0, then V t arg =V min ;

[0082] If |F err |<x, and |F err |>0, then V t arg =V max ;

[0083] V t arg is the motor target speed, K P is the proportional control coefficient.

[0084] The brake pressure control module provided by the present invention is mainly used in pure electric or hybrid vehicles.

[0085] By calculating the target master cylinder piston thrust, calculating the actual thrust, adjusting the motor speed according to the target master cylinder piston thrust and the actual piston thrust, and then controlling the master cylinder pressure to prevent anti-lock, the present invention can at least achieve the following technical effects:

[0086] 1. The present invention can effectively prevent the operating conditions such as excessive master cylinder pressure and hardware damage caused by triggering the anti-lock braking function.

[0087] 2. The present invention can prevent the pressure pulse generated by the triggering of the system's anti-lock braking function from causing the mechanical transmission system to get stuck, the pressure cannot be released, and other problems.

[0088] 3. When the pressure reduction function is triggered, the anti-lock braking function of the braking system can work normally.

[0089] 4. The present invention can actively adjust the brake pressure through the motor between the target master cylinder piston thrust and the actual piston thrust, so that the brake pressure meets the braking demand, and can avoid the damage and safety defects caused by excessively high or low brake pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] The drawings of the present invention are intended to illustrate the general characteristics of the methods, structures and / or materials used in specific exemplary embodiments of the present invention, and to supplement the description in the specification. However, the drawings of the present invention are schematic diagrams not drawn to scale, and thus may not accurately reflect the precise structure or performance characteristics of any given embodiment, and the drawings of the present invention should not be interpreted as limiting or restricting the range of values ​​or properties covered by the exemplary embodiments of the present invention. The present invention is further described in detail below in conjunction with the drawings and specific embodiments:

[0091] Figure 1 It is a control flow diagram of the present invention.

[0092] Figure 2 It is a schematic diagram of the brake thrust control logic of the present invention. DETAILED DESCRIPTION

[0093] The following is an explanation of the embodiments of the present invention by specific specific embodiments, and those skilled in the art can fully understand other advantages and technical effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through different specific embodiments, and the details in this specification can also be applied based on different viewpoints, and various modifications or changes can be made without deviating from the general design concept of the invention. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. The following exemplary embodiments of the present invention can be implemented in a variety of different forms and should not be interpreted as being limited to the specific embodiments described here. It should be understood that these embodiments are provided to make the disclosure of the present invention thorough and complete, and to fully convey the technical solutions of these exemplary specific embodiments to those skilled in the art. It should be understood that when an element is referred to as "connected" or "coupled" to another element, the element can be directly connected or coupled to another element, or there can be an intermediate element. The difference is that when an element is referred to as "directly connected" or "directly coupled" to another element, there is no intermediate element. In all the drawings, the same reference numerals always represent the same elements.

[0094] First embodiment;

[0095] The present invention provides a brake pressure control method for an electronic power-assisted brake system, comprising the following steps:

[0096] S1, determine whether to trigger the pressure control according to the working state of the anti-lock braking function and the target pressure. If triggered, execute step S2, otherwise the electronic power-assisted braking system provides braking force according to normal driving conditions;

[0097] S2, brake master cylinder pressure build-up, calculate the target master cylinder piston thrust according to the braking intention requirement, vehicle speed requirement, maximum wheel cylinder pressure requirement and actual master cylinder pressure requirement;

[0098] S3, calculating the actual thrust, calculating the actual piston thrust according to the master cylinder pressure signal state, the actual master cylinder pressure and the master cylinder pressure to piston thrust conversion coefficient;

[0099] S4, adjusts the motor speed according to the target master cylinder piston thrust and the actual piston thrust, thereby controlling the master cylinder pressure to prevent anti-lock.

[0100] Second embodiment;

[0101] refer to Figure 1 As shown, the present invention provides a brake pressure control method for an electronic power-assisted brake system, comprising the following steps:

[0102] S1, judging the triggering, when the anti-lock braking function is triggered, and the anti-lock braking function triggering signal is valid, and the anti-lock braking function is not invalid, and the target hydraulic pressure is greater than 1 bar, the pressure reduction function is triggered, that is, the brake pressure control function of the present invention is started; if any of the above conditions is not met, the brake pressure control function is exited, and the electronic power-assisted braking system provides braking force according to normal driving conditions;

[0103] S2, brake master cylinder pressure build-up, calculate the target master cylinder piston thrust according to the braking intention requirement, vehicle speed requirement, maximum wheel cylinder pressure requirement and actual master cylinder pressure requirement, including:

[0104] When the pressure reduction function is triggered, due to the fluctuation of the master cylinder pressure, in order to ensure that the valley pressure during the fluctuation is greater than the pressure required by the driver, a positive offset is added to the hydraulic pressure required for the braking intention. The positive offset increases with the increase of the target hydraulic pressure. The target hydraulic pressure is obtained from the external signal. The braking intention requirement is calculated using the following formula (1);

[0105] P t arg =P t arg 1 +P off (1)

[0106] P t arg is the hydraulic pressure required for the braking intention after processing, P t arg 1 is the driver demand pressure, P off is the brake intention hydraulic pressure offset;

[0107] When the driver steps on the pedal hard, the decoupling gap of the electronic power brake system will be overcome. At this time, the ABS is triggered, and the master cylinder pressure fluctuates, which will cause the pedal stroke to fluctuate, resulting in changes in the required hydraulic pressure. This phenomenon will aggravate the fluctuation of the master cylinder pressure, so it is preferred to filter the target master cylinder pressure at this time. In order to prevent the need for rapid pressure increase, only the target pressure drop is limited;

[0108] Vehicle speed required hydraulic pressure P vehs At the maximum support fluid pressure P max and the minimum support fluid pressure P min The range is selected according to the vehicle speed. When the vehicle speed is low, the ABS function will be disabled, and when the vehicle speed is low, the vehicle's demand for high hydraulic pressure is reduced. Therefore, the hydraulic pressure demand that is required to reduce the demand when the vehicle speed is low is calculated using the following formula (2):

[0109] P vehs =K v (P max -P min ) (2);

[0110] Pvehs K is the hydraulic pressure required by vehicle speed, v is the vehicle speed coefficient, which increases with the speed, ranging from 0 to 1, P max , P min are the maximum and minimum support pressures respectively;

[0111] Since ABS does not have the function of active boosting, when ABS is triggered, the ability of wheel cylinder boosting is completely determined by the master cylinder pressure. Therefore, the required master cylinder pressure P whlt arg Should be greater than the maximum wheel cylinder pressure P whl max In addition, due to the pressure fluctuation when ABS is working, a certain pressure needs to be added to the maximum wheel cylinder pressure as the required pressure P off1 When the road adhesion coefficient suddenly increases, the wheel cylinder also suddenly increases pressure, which may cause the master cylinder pressure to drop suddenly. Therefore, when the actual pressure is less than or slightly greater than the maximum wheel cylinder pressure, a certain pressure P needs to be added to the maximum wheel cylinder pressure. off2 , P off2 As the difference between the target actual master cylinder pressure and the actual maximum wheel cylinder pressure decreases, it increases. Since some ABS suppliers cannot provide the maximum wheel cylinder pressure, the maximum wheel cylinder pressure uses the high adhesion brake pressure at this time. The maximum wheel cylinder pressure requirement is calculated using the following formula (3):

[0112] P whlt arg =P whl max +P off1 +P off2 (3)

[0113] P whlt arg is the master cylinder hydraulic pressure required for the maximum wheel cylinder pressure, P whl max is the maximum wheel cylinder pressure, P off1 , P off2 The hydraulic pressure offset added to prevent the pressure from fluctuating below the required value;

[0114] Preferably, in order to prevent the maximum wheel cylinder pressure from suddenly increasing after it drops, and the XBS system not responding in time to affect the ABS operation, it is necessary to limit the superimposed target hydraulic pressure to a certain descending slope, and the limiting method is similar to the method of limiting the braking intention hydraulic pressure. However, since the slope of this part of the limit is small, it may cause the pressure to be released too slowly, so it is necessary to limit the limiting time;

[0115] The required master cylinder hydraulic pressure is calculated using the following formula (4):

[0116] P t arg all =min(P t arg ,P vehs ,P whlt arg )-P deoff (4)

[0117] P t arg all is the required master cylinder hydraulic pressure, P deoff The pressure value that needs to be reduced is obtained based on the actual master cylinder pressure;

[0118] Preferably, in order to prevent excessive fluctuation of the thrust, the thrust obtained is low-pass filtered before output;

[0119] The required master cylinder hydraulic pressure is calculated by using the following formula (5):

[0120] F t arg =P targ all β (5)

[0121] F t arg is the target master cylinder piston thrust, β is the cylinder pressure to thrust conversion coefficient;

[0122] S3, calculating the actual thrust, calculating the actual piston thrust according to the master cylinder pressure signal state, the actual master cylinder pressure and the master cylinder pressure to piston thrust conversion coefficient, including:

[0123] There is a master cylinder pressure signal, and the actual piston thrust is calculated using the following formula (6);

[0124] F a =P a β (6)

[0125] F a is the actual thrust calculated, P a is the actual master cylinder pressure, β is the hydraulic pressure to thrust conversion coefficient;

[0126] There is no master cylinder pressure signal. When there is no master cylinder pressure signal, the actual motor outputs torque T a , actual motor speed v, conversion coefficient α, inertia force F g The actual thrust F of the output a Calculate the actual piston thrust using the following formula (7):

[0127] F a =T a ·v·α-F g (7)

[0128] T a is the motor output torque, v is the motor speed, α is the torque-thrust conversion coefficient, F g is the inertial force;

[0129] S4, adjusts the motor speed according to the target master cylinder piston thrust and the actual piston thrust, thereby controlling the master cylinder pressure to prevent anti-lock, including:

[0130] The thrust deviation F is calculated using the following formula (7): err ;

[0131] F err =F t arg -F a (7)

[0132] x is the dead zone threshold, V max ,V min They are the speed output given values ​​in the forward and reverse dead zones respectively;

[0133] refer to Figure 2 As shown, the thrust is controlled by P control plus output target dead zone. The output control target is the motor speed, and the motor output target should be controlled not to be zero, so as to ensure that the system is at a low speed time ratio and reduce the influence of the static friction of the system on the control. The output control target is the motor speed, and the motor output target should be controlled not to be zero;

[0134] If |F err |>x, then V t arg =K P -F err ;

[0135] If |F err |<x, and |F err |<0, then V t arg =V min ;

[0136] If |F err |<x, and |F err |>0, then V t arg =V max ;

[0137] V t arg is the motor target speed, K P is the proportional control coefficient.

[0138] Third embodiment;

[0139] The present invention provides a brake pressure control module, which is used in an electronic power-assisted brake system, comprising:

[0140] A judgment unit, which judges whether to trigger the brake pressure control module according to the working state of the anti-lock braking function of the electronic power-assisted braking system and the target pressure. If not, the electronic power-assisted braking system provides braking force according to the normal driving condition;

[0141] A brake master cylinder pressure control unit calculates a target master cylinder piston thrust according to a braking intention requirement, a vehicle speed requirement, a maximum wheel cylinder pressure requirement, and an actual master cylinder pressure requirement;

[0142] an actual thrust calculation unit, which calculates the actual piston thrust according to the master cylinder pressure signal state, the actual master cylinder pressure and the master cylinder pressure to piston thrust conversion coefficient;

[0143] The motor speed control unit adjusts the motor speed according to the target master cylinder piston thrust and the actual piston thrust, thereby controlling the master cylinder pressure to prevent anti-lock.

[0144] Fourth embodiment;

[0145] The present invention provides a brake pressure control module, which is used in an electronic power-assisted brake system, comprising:

[0146] The judging unit judges whether to trigger the brake pressure control module according to the working state of the anti-lock braking function of the electronic power-assisted braking system and the target pressure. When the anti-lock braking function is triggered and the trigger signal of the anti-lock braking function is valid, the anti-lock braking function is not invalid, and the target fluid pressure is greater than 1 bar, the pressure reduction function is triggered, that is, the brake pressure control function of the present invention is started; if any of the above conditions is not met, the brake pressure control function is exited, and the electronic power-assisted braking system provides braking force according to normal driving conditions;

[0147] The brake master cylinder pressure control unit calculates the target master cylinder piston thrust according to the braking intention requirement, the vehicle speed requirement, the maximum wheel cylinder pressure requirement and the actual master cylinder pressure requirement. The brake master cylinder pressure control unit calculates the target master cylinder piston thrust according to the braking intention requirement, the vehicle speed requirement, the maximum wheel cylinder pressure requirement and the actual master cylinder pressure requirement. The specific process is as follows;

[0148] The braking intention requirement is calculated using the following formula (1):

[0149] P t arg =P t arg 1 +P off (1)

[0150] P t arg is the hydraulic pressure required for the braking intention after processing, P t arg 1 is the driver demand pressure, P off is the brake intention hydraulic pressure offset;

[0151] The vehicle speed requirement is calculated using the following formula (2):

[0152] P vehs =K v (P max -P min ) (2);

[0153] P vehs K is the hydraulic pressure required by vehicle speed, v is the vehicle speed coefficient, P max , P minare the maximum and minimum support pressures respectively;

[0154] The maximum wheel cylinder pressure requirement is calculated using the following formula (3):

[0155]

[0156] P whlt arg is the master cylinder hydraulic pressure required for the maximum wheel cylinder pressure, P whl max is the maximum wheel cylinder pressure, P off1 , P off2 The hydraulic pressure offset added to prevent the pressure from fluctuating below the required value;

[0157] The required master cylinder hydraulic pressure is calculated using the following formula (4):

[0158] P t arg all =min(P t arg ,P vehs ,P whlt arg )-P deoff (4)

[0159] P t arg all is the required master cylinder hydraulic pressure, P deoff The pressure value that needs to be reduced is obtained based on the actual master cylinder pressure;

[0160] The required master cylinder hydraulic pressure is calculated by using the following formula (5):

[0161] F t arg =P t arg all β (5)

[0162] F t arg is the target master cylinder piston thrust, β is the cylinder pressure to thrust conversion coefficient;

[0163] The actual thrust calculation unit calculates the actual piston thrust according to the master cylinder pressure signal state, the actual master cylinder pressure and the master cylinder pressure to piston thrust conversion coefficient. The specific process is as follows;

[0164] There is a master cylinder pressure signal, and the actual piston thrust is calculated using the following formula (6);

[0165] F a =P a β (6)

[0166] F a is the actual thrust calculated, P a is the actual master cylinder pressure, β is the hydraulic pressure to thrust conversion coefficient;

[0167] In the absence of a master cylinder pressure signal, the actual piston thrust is calculated using the following formula (7):

[0168] F a =T a ·v·α-F g (7)

[0169] T a is the motor output torque, v is the motor speed, α is the torque-thrust conversion coefficient, F g is the inertial force;

[0170] The motor speed control unit adjusts the motor speed according to the target master cylinder piston thrust and the actual piston thrust, and then controls the master cylinder pressure to prevent anti-lock. The specific process is as follows;

[0171] The thrust deviation F is calculated using the following formula (8): err ;

[0172] F err =F t arg -F a (8)

[0173] x is the dead zone threshold, V max ,V min They are the speed output given values ​​in the forward and reverse dead zones respectively;

[0174] If |F err |>x, then V t arg =K P ×F err ;

[0175] If |F err |<x, and |F err |<0, then V t arg =V min ;

[0176] If |F err |<x, and |F err |>0, then V t arg =V max ;

[0177] V t arg is the motor target speed, K P is the proportional control coefficient.

[0178] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. It will also be understood that, unless expressly defined herein, terms such as those defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not interpreted in an ideal or overly formal sense.

[0179] The present invention has been described in detail above through specific implementation modes and embodiments, but these do not constitute limitations of the present invention. Without departing from the principles of the present invention, those skilled in the art may also make many variations and improvements, which should also be regarded as the protection scope of the present invention.

Claims

1. A brake pressure control method for an electronic power-assisted brake system, characterized in that: The following steps are involved: S1, determine whether to trigger the pressure control according to the working state of the anti-lock braking function and the target pressure. If triggered, execute step S2, otherwise the electronic power-assisted braking system provides braking force according to normal driving conditions; S2, brake master cylinder pressure build-up, calculate the target master cylinder piston thrust according to the braking intention requirement, vehicle speed requirement, maximum wheel cylinder pressure requirement and actual master cylinder pressure requirement; S3, calculating the actual thrust, calculating the actual piston thrust according to the master cylinder pressure signal state, the actual master cylinder pressure and the master cylinder pressure to piston thrust conversion coefficient; S4, adjusts the motor speed according to the target master cylinder piston thrust and the actual piston thrust, thereby controlling the master cylinder pressure to prevent anti-lock.

2. The brake pressure control method according to claim 1, characterized in that: When implementing step S1, it includes: If the anti-lock braking function is triggered, the anti-lock braking function has not failed, and the target hydraulic pressure is greater than 1 bar, the pressure control is triggered, otherwise the electronic power-assisted braking system provides braking force according to normal driving conditions.

3. The brake pressure control method according to claim 1, characterized in that: When implementing step S2, it includes: The braking intention requirement is calculated using the following formula (1): P targ =P targ1 +P off (1) P targ is the hydraulic pressure required for the braking intention after processing, P targ1 is the driver demand pressure, P off is the brake intention hydraulic pressure offset; The vehicle speed requirement is calculated using the following formula (2): P vehs =K v (P max -P min )(2); P vehs K is the hydraulic pressure required by vehicle speed, v is the vehicle speed coefficient, P max , P min are the maximum and minimum support pressures respectively; The maximum wheel cylinder pressure requirement is calculated using the following formula (3): P whltarg =P whlmax +P off1 +P off2 (3) P whltarg is the master cylinder hydraulic pressure required for the maximum wheel cylinder pressure, P whlmax is the maximum wheel cylinder pressure, P off1 , P off2 The hydraulic pressure offset added to prevent the pressure from fluctuating below the required value; The required master cylinder hydraulic pressure is calculated using the following formula (4): P targall =min(P targ ,P vehs ,P whltarg )-P deoff (4) P targall is the required master cylinder hydraulic pressure, P deoff The pressure value that needs to be reduced is obtained based on the actual master cylinder pressure; The required master cylinder hydraulic pressure is calculated by using the following formula (5): F targ =P targall ·b (5) F targ is the target master cylinder piston thrust, and β is the cylinder pressure to thrust conversion coefficient.

4. The brake pressure control method according to claim 1, characterized in that: When implementing step S3, it includes: There is a master cylinder pressure signal, and the actual piston thrust is calculated using the following formula (6); F a =P a ·b (6) F a is the actual thrust calculated, P a is the actual master cylinder pressure, β is the hydraulic pressure to thrust conversion coefficient; In the absence of a master cylinder pressure signal, the actual piston thrust is calculated using the following formula (7): F a =T a ·v·α-F g (7) T a is the motor output torque, v is the motor speed, α is the torque-thrust conversion coefficient, F g It is the inertial force.

5. The brake pressure control method according to claim 1, characterized in that: When implementing step S4, it includes: The thrust deviation F is calculated using the following formula (8): err ; F err =F targ -F a (8) x is the dead zone threshold, V max ,V min They are the speed output given values ​​in the forward and reverse dead zones respectively; If |F err |>x, then V targ =K P -F err ; If |F err |<x, and |F err |<0, then V targ =V min ; If |F err |<x, and |F err |>0, then V targ =V max ; V targ is the motor target speed, K P is the proportional control coefficient.

6. A brake pressure control module, used in an electronic power-assisted brake system, characterized in that: include: A judgment unit, which judges whether to trigger the brake pressure control module according to the working state of the anti-lock braking function of the electronic power-assisted braking system and the target pressure. If not, the electronic power-assisted braking system provides braking force according to the normal driving condition; A brake master cylinder pressure control unit calculates a target master cylinder piston thrust according to a braking intention requirement, a vehicle speed requirement, a maximum wheel cylinder pressure requirement, and an actual master cylinder pressure requirement; an actual thrust calculation unit, which calculates the actual piston thrust according to the master cylinder pressure signal state, the actual master cylinder pressure and the master cylinder pressure to piston thrust conversion coefficient; The motor speed control unit adjusts the motor speed according to the target master cylinder piston thrust and the actual piston thrust, thereby controlling the master cylinder pressure to prevent anti-lock.

7. The brake pressure control module according to claim 6, characterized in that: The judgment conditions of the judgment unit include: If the anti-lock braking function is triggered, the anti-lock braking function has not failed, and the target hydraulic pressure is greater than 1 bar, the pressure control is triggered, otherwise the electronic power-assisted braking system provides braking force according to normal driving conditions.

8. The brake pressure control module according to claim 6, wherein: The master cylinder pressure control unit calculates the target master cylinder piston thrust including: The braking intention requirement is calculated using the following formula (1): P targ =P targ1 +P off (1) P targ is the hydraulic pressure required for the braking intention after processing, P targ1 is the driver demand pressure, P off is the brake intention hydraulic pressure offset; The vehicle speed requirement is calculated using the following formula (2): P vehs =K v (P max -P min )(2); P vehs K is the hydraulic pressure required by vehicle speed, v is the vehicle speed coefficient, P max , P min are the maximum and minimum support pressures respectively; The maximum wheel cylinder pressure requirement is calculated using the following formula (3): P whltarg =P whlmax +P off1 +P off2 (3) P whltarg is the master cylinder hydraulic pressure required for the maximum wheel cylinder pressure, P whlmax is the maximum wheel cylinder pressure, P off1 , P off2 The hydraulic pressure offset added to prevent the pressure from fluctuating below the required value; The required master cylinder hydraulic pressure is calculated using the following formula (4): P targall =min(P targ ,P vehs ,P whltarg )-P deoff (4) P targall is the required master cylinder hydraulic pressure, P deoff The pressure value that needs to be reduced is obtained based on the actual master cylinder pressure; The required master cylinder hydraulic pressure is calculated by using the following formula (5): F targ =P targall ·b(5) F targ is the target master cylinder piston thrust, and β is the cylinder pressure to thrust conversion coefficient.

9. The brake pressure control module according to claim 6, characterized in that: The actual thrust calculation unit calculates the actual piston thrust including: There is a master cylinder pressure signal, and the actual piston thrust is calculated using the following formula (6); F a =P a ·b (6) F a is the actual thrust calculated, P a is the actual master cylinder pressure, β is the hydraulic pressure to thrust conversion coefficient; In the absence of a master cylinder pressure signal, the actual piston thrust is calculated using the following formula (7): F a =T a ·v·α-F g (7) T a is the motor output torque, v is the motor speed, α is the torque-thrust conversion coefficient, F g It is the inertial force.

10. The brake pressure control module according to claim 6, wherein: The motor speed control unit adjusts the motor speed including: The thrust deviation F is calculated using the following formula (8): err ; F err =F targ -F a (8) x is the dead zone threshold, V max ,V min They are the speed output given values ​​in the forward and reverse dead zones respectively; If |F err |>x, then V targ =K P -F err ; If |F err |<x, and |F err |<0, then V targ =V min ; If |F err |<x, and |F err |>0, then V targ =V max ; V targ is the motor target speed, K P is the proportional control coefficient.

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