Vehicle auxiliary braking system and method

Abstract

The invention provides a vehicle auxiliary braking system and method. The system comprises a braking electronic booster, an electronic control unit, a stroke sensor, a main cylinder pressure sensor, a braking pedal, a braking main cylinder, a whole vehicle control unit and a driving motor. And when the stroke sensor is normal, the braking electronic booster performs normal electric boosting and requests energy recovery electric braking torque according to the opening signal of the braking pedal. Generally, when a stroke sensor fails due to double-path faults and a brake electronic booster has no pedal opening signal and cannot perform electric power assistance and request electric brake torque, the vehicle only has mechanical brake at the moment, and the working condition is a dangerous working condition. Under the condition that the stroke sensor fails due to the double-circuit fault, the brake pedal opening analog signal is obtained through the pressure signal of the brake master cylinder, so that the electronic booster can identify the brake intention of a driver under the condition that the stroke sensor fails due to the double-circuit fault, a driving motor is requested to carry out auxiliary electric braking, and the safety performance of a vehicle is improved.

Description

Technical Field

[0001] The present invention belongs to the field of vehicle braking systems, and in particular relates to a vehicle auxiliary braking system and method. Background Art

[0002] For vehicles with electronic hydraulic braking systems (EHB), when the travel sensor of the braking system fails, the EHB cannot determine the driver's intention and cannot perform normal electric assistance. At this time, only mechanical braking is available, but the mechanical braking force can only meet emergency braking requirements, which is a dangerous condition.

[0003] Patent application CN116161008A discloses a redundant control method for the travel sensor signal of a brake electric booster. When a single-channel travel signal in the travel sensor fails, the two-channel signals in the travel sensor cannot be verified with each other. The added master cylinder pressure sensor signal can be converted into a travel signal for verification, and a valid travel signal can be output, thereby ensuring the braking force of the whole vehicle after a single-channel failure in the travel sensor itself, thereby improving driving safety. However, when both travel signals in the travel sensor fail, it cannot be verified, and thus cannot output a valid travel signal, and cannot achieve vehicle braking assistance, which is not conducive to vehicle safety. Summary of the invention

[0004] The purpose of the present invention is to provide a vehicle auxiliary braking system and method to solve the problem that the vehicle cannot provide braking assistance after the dual-path signals of the travel sensor fail, thereby improving vehicle safety.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A vehicle auxiliary braking system includes a brake electronic booster, an electronic control unit, a travel sensor, a master cylinder pressure sensor, a brake pedal, a brake master cylinder, a vehicle control unit, and a drive motor;

[0007] The travel sensor, the master cylinder pressure sensor, and the electronic brake booster are electrically connected to the electronic control unit respectively, and the electronic control unit and the drive motor are electrically connected to the vehicle control unit respectively;

[0008] The travel sensor collects the brake pedal opening signal and transmits the brake pedal opening signal to the electronic control unit;

[0009] The master cylinder pressure sensor collects the pressure signal of the brake master cylinder and transmits the pressure signal of the brake master cylinder to the electronic control unit;

[0010] The electronic control unit is responsible for converting the pressure signal of the brake master cylinder into a brake pedal opening analog signal when the stroke sensor fails in both circuits, and transmitting the brake pedal opening analog signal to the vehicle control unit; the electronic control unit outputs an electric brake demand signal according to the brake pedal opening signal or the brake pedal opening analog signal, and transmits the electric brake demand signal to the vehicle control unit, and the vehicle controller then transmits the electric brake demand signal to the drive motor;

[0011] The electronic brake booster is responsible for electric braking assistance;

[0012] The vehicle control unit receives the brake pedal opening simulation signal, controls the drive motor to output reverse torque, and performs auxiliary electric braking.

[0013] In the case of a double-circuit fault of the travel sensor, the electronic brake booster cannot identify the driver's intention and cannot assist in braking. Only mechanical pedal force braking can meet the braking force requirements of emergency braking. In this case, the vehicle hopes that the greater the braking intervention, the better, to improve safety performance. The present invention obtains a brake pedal opening simulation signal through the pressure signal of the brake master cylinder, so that the electronic brake booster can identify the driver's braking intention in the case of a double-circuit fault of the travel sensor, and requests the drive motor to perform auxiliary electric braking according to the brake pedal opening simulation signal, thereby improving the safety performance of the vehicle.

[0014] Furthermore, the relationship between the pressure signal of the brake master cylinder and the brake pedal opening analog signal is shown in the following formula:

[0015] When P1 is less than P2: Brake pedal opening analog signal = (P1 / P2) × 100%

[0016] When P1 is greater than or equal to P2: Brake pedal opening analog signal = 100%

[0017] Among them, P1 is the pressure signal of the brake master cylinder, and P2 is the maximum pressure of the brake master cylinder when the stroke sensor fails in both paths.

[0018] Furthermore, the relationship between the anti-drag torque and the brake pedal opening analog signal is as follows:

[0019] Anti-drag torque = brake pedal opening analog signal × maximum anti-drag torque.

[0020] Furthermore, the vehicle control unit receives the brake pedal opening analog signal and controls the high voltage power supply to the vehicle. Without the brake pedal opening signal, the vehicle cannot be powered on by high voltage, and the instrument fault cannot be read, which hinders troubleshooting and vehicle movement. After obtaining the brake pedal opening analog signal through the brake master cylinder pressure signal, the brake pedal opening analog signal can be used to realize high voltage power supply to the vehicle, which can effectively solve the problem of the vehicle being unable to start after the travel sensor fails.

[0021] Based on the same inventive concept, the present invention also provides a vehicle auxiliary braking method, comprising the following process:

[0022] The travel sensor collects the brake pedal opening signal;

[0023] The master cylinder pressure sensor collects the pressure signal of the brake master cylinder;

[0024] When the brake pedal opening signal is detected, the brake is electrically assisted according to the brake pedal opening signal;

[0025] When the brake pedal opening signal is not detected, the pressure signal of the brake master cylinder is converted into a brake pedal opening simulation signal, and according to the brake pedal opening simulation signal, the drive motor is requested to output a reverse torque for auxiliary braking.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention obtains a brake pedal opening analog signal through a pressure signal of a brake master cylinder, so that the brake electronic booster can recognize the driver's braking intention even when a stroke sensor fails in both paths, and requests a drive motor to perform auxiliary electric braking according to the brake pedal opening analog signal, thereby improving the vehicle safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of a vehicle auxiliary braking system of the present invention;

[0029] Figure 2 It is the corresponding relationship diagram between the brake master cylinder pressure and the brake pedal opening;

[0030] Figure 3 This is the corresponding relationship diagram of brake master cylinder pressure, brake pedal opening and anti-drag torque. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0032] Example

[0033] For vehicles with electronic hydraulic brake system (EHB), when the travel sensor of the brake system fails, the EHB cannot judge the driver's intention and cannot provide normal brake assistance. At this time, there is only mechanical braking, and the braking force can only meet the emergency braking requirements, which is a dangerous working condition. In order to increase the braking force, improve the braking deceleration and improve safety after the travel sensor fails, the pressure signal of the brake master cylinder is used in this working condition to simulate the pedal opening signal and the reverse torque of the drive motor to achieve this purpose.

[0034] When the travel sensor fails, it cannot provide a pedal opening signal, which results in the vehicle being unable to connect to high voltage, start the vehicle, move the vehicle, or troubleshoot. Using the pressure signal of the brake master cylinder to simulate the pedal opening signal can effectively solve the problem of the vehicle being unable to start after the travel sensor fails.

[0035] like Figure 1 The vehicle auxiliary braking system of this embodiment includes an electronic control unit, a travel sensor, a master cylinder pressure sensor, a brake pedal, a brake master cylinder, a brake electronic booster, a vehicle control unit, and a drive motor;

[0036] The electronic hydraulic brake system (EHB) includes an electronic control unit, a stroke sensor, a master cylinder pressure sensor, a brake pedal, a brake master cylinder, an electronic brake booster, etc.

[0037] The travel sensor, the master cylinder pressure sensor, and the electronic brake booster are electrically connected to the electronic control unit respectively, and the electronic control unit and the drive motor are electrically connected to the vehicle control unit respectively;

[0038] The travel sensor collects the brake pedal opening signal and transmits the brake pedal opening signal to the electronic control unit;

[0039] The master cylinder pressure sensor collects the pressure signal of the brake master cylinder and transmits the pressure signal of the brake master cylinder to the electronic control unit;

[0040] The electronic control unit is responsible for converting the pressure signal of the brake master cylinder into a brake pedal opening analog signal when the stroke sensor fails in both circuits, and transmitting the brake pedal opening analog signal to the vehicle control unit; the electronic control unit outputs an electric brake demand signal according to the brake pedal opening signal or the brake pedal opening analog signal, and transmits the electric brake demand signal to the vehicle control unit, and the vehicle controller then transmits the electric brake demand signal to the drive motor;

[0041] The electronic brake booster is responsible for electric braking assistance;

[0042] The vehicle control unit receives the brake pedal opening simulation signal, controls the drive motor to output reverse torque, and performs auxiliary electric braking.

[0043] The vehicle auxiliary braking method provided in this embodiment obtains a brake pedal opening simulation signal by means of the pressure signal of the brake master cylinder collected by the master cylinder pressure sensor when the stroke sensor fails, and uses the signal to request the drive motor to output a reverse torque for auxiliary braking.

[0044] 1) First, the prerequisite for using the pressure signal of the brake master cylinder to obtain the brake pedal opening analog signal is that the EHB will report a fault code when the travel sensor fails, and judge that this type of fault is a travel sensor failure. When the EHB reports a travel sensor failure, this function is triggered and the pressure signal of the brake master cylinder is synchronously converted into a brake pedal opening analog signal.

[0045] 2) Logic of the correspondence between the master cylinder pressure and the pedal opening signal: When the travel sensor fails, the EHB cannot recognize the driving intention and cannot perform electric assistance, and only the brake pedal force is used for braking. At this time, the master cylinder pressure of the brake system only comes from the brake pedal force. Under the action of the brake pedal force of 600-700N, the master cylinder pressure can only reach 3-4MPa. The braking force generated under this pressure can only meet the emergency braking requirements of GB12676, and the braking safety is insufficient.

[0046] The deeper the brake pedal is pressed (i.e. the greater the pedal opening), the greater the brake master cylinder pressure. This pressure has an upper limit due to the mechanical structure. For example, if a vehicle is equipped with EHB, when the EHB electric power assist fails and enters the backup brake (i.e. pure mechanical brake), it has been tested that when the pedal force is 600-700N, the pedal opening is close to 100%, and the brake master cylinder pressure can reach 3-4MPa. 0-3MPa can be corresponded to 0-100% of the brake pedal opening to obtain a brake pedal opening simulation signal. The following can be obtained based on the increase in the brake master cylinder pressure: Figure 2 The corresponding relationship of the brake pedal opening simulation signal is shown.

[0047] The relationship between the pressure signal of the brake master cylinder and the brake pedal opening analog signal is shown in the following formula:

[0048] When P1 is less than P2: Brake pedal opening analog signal = (P1 / P2) × 100%

[0049] When P1 is greater than or equal to P2: Brake pedal opening analog signal = 100%

[0050] Among them, P1 is the pressure signal of the brake master cylinder, and P2 is the maximum pressure of the brake master cylinder when the stroke sensor fails in both paths.

[0051] 3) EHB has the function of braking energy recovery. Under normal circumstances, EHB receives information such as vehicle speed, gear position, and maximum available braking recovery torque from the vehicle control unit, and determines whether the conditions for starting the braking energy feedback function are met at this time; if the conditions are met, the braking energy recovery function is executed. According to the dynamic requirements, electric braking is used first to meet the total braking demand. EHB requests the vehicle control unit to recover the electric braking torque of the braking energy and calculates the minimum hydraulic braking force to ensure the smoothness and stability of the vehicle braking, while recovering the braking energy to the maximum extent.

[0052] When the travel sensor fails, the EHB cannot realize the braking energy recovery function. At this time, the EHB cannot recognize the driver's intention and will not request the vehicle control unit to recover the electric braking torque.

[0053] To improve safety, the obtained brake pedal opening analog signal is used to request the drive motor to output reverse torque for auxiliary braking, thereby increasing the braking deceleration.

[0054] The relationship between the anti-drag torque and the brake pedal opening analog signal is as follows:

[0055] Anti-drag torque = brake pedal opening analog signal × maximum anti-drag torque.

[0056] like Figure 3 When the travel sensor fails, the brake pedal opening analog signal changes with the brake master cylinder pressure, and the requested drive motor back-drag torque and the actual response torque change with the brake pedal opening analog signal (the linear torque decrease section is due to the exit of the electric brake when the vehicle speed is lower than 15km / h, which is the vehicle control logic).

[0057] 4) Without the brake pedal opening signal, the vehicle cannot be powered on with high voltage (for example, the high voltage operation on the vehicle requires turning the key after the brake pedal opening is greater than 15%), and the instrument fault cannot be read, which hinders troubleshooting and vehicle movement. After obtaining the brake pedal opening analog signal through the pressure signal of the brake master cylinder, the brake pedal opening analog signal obtained when the pedal is stepped on can be used to power on the vehicle with high voltage.

[0058] For example, when the brake master cylinder pressure is greater than 3MPa, the brake pedal opening is 100%. The maximum anti-drag torque is 220Nm, and the drive motor is required to output anti-drag torque = brake pedal opening analog signal × 220Nm. For example, when the brake master cylinder pressure is 1.5MPa, the brake pedal opening analog signal is 50%, and the drive motor is required to output an anti-drag torque of 110Nm.

[0059] Brake pedal opening: refers to the extent to which the brake pedal sinks from a stationary state to when it is depressed.

[0060] Electric braking back-drag torque: refers to the reverse torque generated by the motor during vehicle deceleration or braking, which is used to help the vehicle decelerate or maintain vehicle stability, achieve deceleration control and energy recovery.

[0061] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A vehicle auxiliary braking system, characterized in that: Including brake electronic booster, electronic control unit, travel sensor, master cylinder pressure sensor, brake pedal, brake master cylinder, vehicle control unit, drive motor; The travel sensor, the master cylinder pressure sensor, and the electronic brake booster are electrically connected to the electronic control unit respectively, and the electronic control unit and the drive motor are electrically connected to the vehicle control unit respectively; The travel sensor collects the brake pedal opening signal and transmits the brake pedal opening signal to the electronic control unit; The master cylinder pressure sensor collects the pressure signal of the brake master cylinder and transmits the pressure signal of the brake master cylinder to the electronic control unit; The electronic control unit is responsible for converting the pressure signal of the brake master cylinder into a brake pedal opening analog signal when the stroke sensor fails in both circuits, and transmitting the brake pedal opening analog signal to the vehicle control unit; the electronic control unit outputs an electric brake demand signal according to the brake pedal opening signal or the brake pedal opening analog signal, and transmits the electric brake demand signal to the vehicle control unit, and the vehicle controller then transmits the electric brake demand signal to the drive motor; The electronic brake booster is responsible for electric braking assistance; The vehicle control unit receives the brake pedal opening simulation signal, controls the drive motor to output reverse torque, and performs auxiliary electric braking.

2. The vehicle auxiliary braking system according to claim 1, characterized in that: The relationship between the pressure signal of the brake master cylinder and the brake pedal opening analog signal is shown in the following formula: When P1 is less than P2: Brake pedal opening analog signal = (P1 / P2) × 100% When P1 is greater than or equal to P2: Brake pedal opening analog signal = 100% Among them, P1 is the pressure signal of the brake master cylinder, and P2 is the maximum pressure of the brake master cylinder when the stroke sensor fails in both paths.

3. The vehicle auxiliary braking system according to claim 1, characterized in that: The relationship between the anti-drag torque and the brake pedal opening analog signal is as follows: Anti-drag torque = brake pedal opening analog signal × maximum anti-drag torque.

4. The vehicle auxiliary braking system according to claim 1, characterized in that: The vehicle control unit receives the brake pedal opening analog signal and controls the high voltage electricity on the vehicle.

5. A vehicle auxiliary braking method, characterized in that: Using the vehicle auxiliary braking system according to any one of claims 1 to 4, The process includes: The travel sensor collects the brake pedal opening signal; The master cylinder pressure sensor collects the pressure signal of the brake master cylinder; When the brake pedal opening signal is detected, the brake is electrically assisted according to the brake pedal opening signal; When the brake pedal opening signal is not detected, the pressure signal of the brake master cylinder is converted into a brake pedal opening simulation signal, and the drive motor is requested to output a reverse torque for auxiliary braking according to the brake pedal opening simulation signal.

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