Vehicle brake failure detection and control method and brake system

Abstract

The present invention discloses a method for detecting and controlling vehicle brake failure. The method includes the following steps: when a vehicle brake fails and no brake system fault is reported, the method enters a brake caliper clearance fault processing flow, determines whether a brake caliper clearance fault is present, and performs a brake caliper clearance fault correction operation. Advantages of the present invention include: accurately detecting the type of brake system failure and providing an alarm; simultaneously, different control strategies are employed for each failure type to ensure that the brake system provides reliable braking force, ensuring safe braking of the system; and, without requiring hardware system modifications, the method can be implemented by integrating it into the brake system, resulting in zero hardware cost and convenient and reliable implementation.

Description

Technical Field

[0001] The present invention relates to the field of automobile brake control, and in particular to a method for detecting and controlling vehicle brake failure. Background Art

[0002] Brake failure can affect safe driving. When a vehicle fails, it's necessary to detect the cause of the failure and issue an alarm. Braking must also be applied as much as possible to ensure safe braking. For example, patent application number 202210938690.X discloses a method and system for controlling vehicle drift and collision avoidance under brake failure conditions. The system includes: determining a brake failure level based on the vehicle's actual and expected longitudinal braking force parameters; determining a longitudinal collision risk index for the vehicle's current state based on the brake failure level; calculating the longitudinal collision risk index based on a high-precision dynamics model of the vehicle with brake failure, and determining a drift control strategy for the disabled vehicle based on the calculated index; and executing the drift control strategy and outputting corresponding action commands, which are then sent to the vehicle's actuators after drift control is triggered. The present invention enables autonomous decision-making and control after a vehicle brake failure, avoiding collision accidents caused by brake failure. The disabled vehicle can be controlled to change its body posture through drifting, utilizing lateral force to achieve rapid braking and collision avoidance maneuvers. This improves the emergency response and backup capabilities of intelligent vehicles in the event of brake failure.

[0003] Although the above patent discloses a control strategy for achieving emergency safe driving under brake failure, no matter what control strategy is used, its basis is to be based on the detected brake failure fault signal. Accurate and reliable detection of vehicle brake failure and its cause is the basis for the execution of the control strategy.

[0004] In the prior art, brake failure includes at least two aspects:

[0005] 1. When the vehicle is driven on certain special roads (bumpy roads and 8-shaped roads, etc.) for a long time, the lateral swing of the vehicle will cause the brake caliper to return to its original position, and the gap between the brake caliper and the brake disc will increase. When the return is excessive, when the driver brakes, the whole vehicle will not decelerate at all, and the brakes will fail.

[0006] 2. The brake circuit fails due to collision with the vehicle chassis, resulting in a traffic accident.

[0007] When faced with brake failure, accurate detection of the cause of the brake failure is the only way to accurately provide a response strategy. How to quickly and accurately detect brake failure and provide a corresponding strategy is crucial to vehicle safety. Although existing technologies can identify failures, the classification and response strategies for failures are insufficient to protect vehicle driving safety. Summary of the Invention

[0008] The purpose of the present invention is to provide an accurate and reliable vehicle brake failure detection and control method for effectively and accurately identifying brake failure and providing corresponding control strategies to ensure driving safety.

[0009] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method for detecting and controlling vehicle brake failure, characterized in that: when the vehicle brake fails and the entire vehicle does not report a brake system fault; entering the brake caliper clearance fault processing process, determining whether it is a brake caliper clearance fault and performing a fault elimination operation on the brake caliper clearance fault.

[0010] The vehicle brake failure judgment method includes: after detecting that the brake pedal is depressed, detecting the vehicle speed signal and converting it into vehicle deceleration, and judging that the vehicle brake failure occurs when the deceleration does not reach the vehicle deceleration value corresponding to the pedal stroke.

[0011] Determining whether it is a brake caliper clearance fault and performing fault elimination operations on the brake caliper clearance fault include: actively building up pressure again and detecting the vehicle's deceleration after the pressure is built up. If the deceleration is greater than the set target threshold, it is determined that there is a brake caliper clearance fault at this time, and active suggestions are made to eliminate the caliper clearance; otherwise, it is determined that it is not a brake caliper clearance fault.

[0012] After determining that the fault is not the brake caliper clearance fault, the single-circuit leakage fault judgment process is entered. Under this process: after closing any circuit in the LFRR circuit or the RFLR circuit, active pressure is built up. If the deceleration is greater than the set target threshold, the closed circuit is judged to be a single-circuit leakage fault.

[0013] In the case of a single-circuit leakage fault, the electronic control unit in the braking system controls the closure of the boost valve of the leakage fault circuit in the LFRR circuit and the RFLR circuit, and then actively builds pressure for braking.

[0014] If there is no leakage fault in the LFRR circuit and the RFLR circuit, it is judged that the braking system has failed, and the braking system directly brakes by actively building pressure.

[0015] In the case of a single-circuit leakage fault, the boost valve of the leakage fault circuit is closed and then active pressure building braking is performed, or in the case of a brake system failure fault, braking is performed directly through active pressure building. If the deceleration of the entire vehicle reaches the deceleration corresponding to the brake pedal stroke, the active boost control is terminated. Otherwise, the electronic control braking system will immediately request the electronic parking brake EPB and energy recovery for auxiliary braking.

[0016] When it is determined that the vehicle is in a single-circuit leakage fault or a brake system failure fault, an alarm reminder will be issued through the alarm system.

[0017] A vehicle braking system adopts a vehicle brake failure detection and control method to perform vehicle brake detection and control.

[0018] The advantages of the present invention are that: the failure type of the braking system can be accurately detected and an alarm reminder can be given; at the same time, each failure type is guaranteed to provide reliable braking force by a different control strategy to ensure safe braking of the system; there is no need to improve the hardware system, and the method can be integrated into the braking system to achieve it, the hardware cost is 0, and the implementation is convenient and reliable.

[0019] 1. When the vehicle is not braking due to reasons such as increased caliper clearance, the electronic control unit controls the motor to build pressure again, eliminating the caliper clearance and then applying pressure, thus preventing brake failure caused by excessive caliper clearance and improving the safety performance of the vehicle's braking system.

[0020] 2. If the electronic control braking system still fails to achieve the expected deceleration and braking after building up pressure again, the electronic control braking system will immediately request the electronic parking brake (EPB) and energy recovery for auxiliary braking to achieve the purpose of rapid deceleration and stopping of the vehicle.

[0021] 3. The present invention is achieved without increasing any hardware cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following is a brief description of the contents and symbols in the drawings of the present invention:

[0023] Figure 1 This is a flow chart of a detection and control method for preventing vehicle brake failure according to the present invention;

[0024] Figure 2 This is a control diagram of the present invention for building up pressure again to eliminate caliper clearance when a single LF&RR circuit fails;

[0025] Figure 3 This is a control diagram of the present invention for re-building pressure to eliminate caliper clearance when a single RF&LR circuit fails;

[0026] Figure 4 This is a control diagram for building up pressure again to eliminate the caliper gap when the present invention detects that there is no circuit failure. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention will be further explained in detail below by describing the best embodiment with reference to the accompanying drawings.

[0028] A vehicle brake failure detection and control method. When the brake system fails while the vehicle is driving, the decoupled electronically controlled brake system detects each brake circuit one by one, identifies the brake system failure mode, and illuminates the warning light. Different control strategies are adopted according to different failure modes to ensure the braking force of the vehicle.

[0029] The vehicle brake system failure conditions include: (1) Under certain special road conditions, such as rough roads or figure-8 conditions, the caliper return amount is too large, resulting in insufficient braking; this condition does not require an alarm; (2) Single brake circuit failure; this condition requires an alarm; (3) The entire brake system fails; this condition requires an alarm;

[0030] For working condition 1, the vehicle's braking force is guaranteed by building up pressure again. For working condition 2, the vehicle's braking force is guaranteed by closing the failed circuit and building up pressure again. For working condition 3, the vehicle's braking force is guaranteed by requesting EPB clamping or brake energy recovery.

[0031] In the decoupled braking system, the brake pedal and wheel braking are independent of each other, and the adjustment of wheel braking pressure does not affect the driver's pedal feel.

[0032] Under certain road conditions, due to reasons such as the increase in the clearance between the brake calipers, the vehicle does not brake when the driver fully depresses the brake pedal. When the braking system recognizes that the difference between the actual braking force of the vehicle and the braking force required by the driver is too large, the electronic control braking system builds up pressure again to achieve the driver's required braking force, thereby achieving the purpose of braking and deceleration of the vehicle. If the electronic control braking system still does not achieve the expected deceleration and braking after building up pressure again, the electronic control braking system will determine the single-circuit leakage by controlling the relevant solenoid valves. If there is still no deceleration. The electronic control braking system will immediately request the electronic parking brake EPB and energy recovery for auxiliary braking to achieve the purpose of quickly decelerating and stopping the vehicle. This forms a method for detecting and controlling vehicle brake failure:

[0033] When the system detects that the driver has applied the brake pedal but the vehicle has not reached the deceleration rate corresponding to the pedal travel, and no brake system fault is reported, the system will proactively build pressure again. If the vehicle decelerates significantly, it is determined that the brake caliper clearance has increased. If the vehicle still does not achieve the expected deceleration, it will determine whether the cause is a single-circuit leak. The system closes the isolation valve in the LFRR circuit and proactively builds pressure. If the vehicle achieves the expected deceleration, it is determined to be a LFRR circuit leak and a brake system fault is reported. Otherwise, if the vehicle does not achieve the expected deceleration, it is determined to be a RFLR circuit leak and a brake system fault is reported. If the system determines that a single-circuit failure has occurred, the electronic control unit (ECU) in the brake system (decoupled brake system) controls the closing of the boost valve in the leaking circuit and proactively builds pressure again for braking. If the vehicle achieves the expected deceleration, the proactive boost control ends. If the vehicle still cannot slow down to a stop, the electronic braking system immediately activates the electronic parking brake (EPB) and energy recovery for auxiliary braking to achieve rapid deceleration and a stop. If the failure does not occur in a single circuit, the electronic control unit (decoupled braking system) in the braking system will directly actively build pressure for braking, preventing brake failure caused by increased caliper clearance. If the electronic control braking system still fails to achieve the desired deceleration and braking after building pressure again, the electronic control braking system will immediately request the electronic parking brake (EPB) and energy recovery for auxiliary braking to achieve the purpose of rapid deceleration and stopping of the vehicle.

[0034] like Figure 1 As shown, a method for detecting and controlling vehicle brake failure includes:

[0035] After the driver presses the brake pedal, the braking system detects that the brake pedal has been pressed. If the vehicle's brakes fail and no brake system fault is reported, the system first enters the brake caliper clearance fault handling process. This process detects whether the brake failure is caused by excessive brake caliper clearance and then restores the brakes by building up pressure again to eliminate the excessive clearance. If the brakes do not fail, the vehicle brakes normally. The reason why the vehicle does not report a system fault is that if a system fault has already been reported, no further fault detection is required. If the system does not fail and the first failure occurs, the system enters the detection and control method steps of this application.

[0036] In this application, brake failure refers to the determination of brake failure when, after detecting that the brake pedal is depressed, the vehicle speed signal is detected and converted into vehicle deceleration. If the vehicle deceleration does not reach the vehicle deceleration value corresponding to the pedal travel, the vehicle is judged to have failed. In other words, brake failure is determined when the vehicle deceleration calculated by the vehicle after the brake pedal is depressed is less than the vehicle deceleration threshold corresponding to the brake pedal stroke.

[0037] After a vehicle fails, this application performs fault detection in the following steps and implements a control strategy based on the corresponding fault to ensure safe and reliable braking, as follows:

[0038] First, determine whether the failure is caused by excessive clearance between the brake calipers. This failure is not irreversible, so first check and control this reversible failure. The strategy is as follows: Figure 4 As shown, the pressure is actively built up again (wherein active pressure building refers to the motor actively boosting the pressure for the decoupling brake system), and the deceleration of the vehicle after the pressure building is detected. If the deceleration is greater than the set target threshold value T1, it is determined that the brake caliper clearance fault is at this time, and the caliper clearance is eliminated by active pressure building; otherwise, it is determined that it is not a brake caliper clearance fault. If the brake caliper clearance is too large, active pressure building can eliminate part of the clearance to restore braking. Therefore, this application first performs an active pressure building to eliminate the possible excessive clearance fault. If the braking force is restored after the pressure building and the deceleration reaches the expected value, it is determined that it is a caliper clearance fault. At this time, the fault has been restored due to the pressure building again. Since this fault is only caused by the increase in the caliper clearance and the braking has been restored, there is no need to alarm, and only pressure building is needed to restore the braking.

[0039] When it is determined that the fault is not the brake caliper gap fault, the single-circuit leakage fault judgment process of the braking system is immediately entered to detect whether the brake failure is caused by leakage in one of the circuits. This application enters the single-circuit leakage fault judgment process after determining that the fault is not the brake caliper gap fault. Under this process: after closing any circuit in the LFRR circuit and the RFLR circuit, active pressure is built up. If the deceleration is greater than the set target threshold target value 1, the closed circuit is judged to be a single-circuit leakage fault.

[0040] like Figure 2 As shown in the figure, during the detection of a single-loop leakage fault, the LFRR loop is closed, the RFLR loop is opened, and then an active pressure buildup is performed. At this time, it is detected whether the deceleration before and after the active pressure buildup reaches the set target threshold value 2. If so, the LFRR loop has a leakage fault; otherwise, Figure 3 As shown, the LFRR circuit is opened, the RFLR circuit is closed, and then an active pressure build-up is performed. At this time, it is detected whether the deceleration before and after the active pressure build-up reaches the set target threshold value 2. If so, the RFLR circuit has a leakage fault; otherwise, it means that there is no leakage fault in both circuits and it is not a single-circuit leakage fault. In this case, it is judged to be a brake system fault.

[0041] The above detection and judgment methods for the three types of brake failure are given as follows:

[0042] Fault condition 1: Brake caliper clearance is too large

[0043] Fault condition 2: Single loop leakage fault, LFRR or RFLR

[0044] Fault condition 3: Braking system failure.

[0045] In fault condition 1, because it is a reversible fault, the brake caliper clearance returns to its original position after pressure is built up. Therefore, recovery control is completed when the fault is detected, that is, both detection and recovery control are based on the pressure building operation again.

[0046] For fault condition 2, under a single-circuit leakage fault, the electronic control unit in the braking system controls the closure of the boost valve of the leakage fault circuit in the LFRR circuit and the RFLR circuit, and then actively builds pressure for braking to ensure that the braking provided by the braking system meets user needs. If the pressure cannot be met after closing the boost valve and then building up pressure again, that is, the vehicle deceleration does not meet the set deceleration requirement or the deceleration cannot reach the deceleration corresponding to the brake pedal stroke, in order to ensure safe and reliable braking, the electronic control braking system will immediately request the electronic parking brake EPB and energy recovery for auxiliary braking, so as to quickly meet the user's braking force requirements, meet the user's deceleration requirements, and avoid safety risks caused by insufficient braking.

[0047] For working condition 3: When the vehicle belongs to neither working condition 1 nor working condition 2, it is judged to be a brake system failure condition. In this case, braking is performed directly by active pressure building. If the deceleration of the whole vehicle reaches the deceleration corresponding to the brake pedal stroke, braking is performed by active boosting to meet the braking deceleration requirement corresponding to the brake pedal stroke. When the brake pedal is released, braking is terminated accordingly, and active boosting control is terminated. Or, if the pressure cannot reach the deceleration corresponding to the brake pedal stroke again, the electronic control braking system will immediately request the electronic parking brake EPB and energy recovery for auxiliary braking.

[0048] In this application, a failure alarm can be given through the vehicle instrument or central control. Failure caused by excessive brake clearance will not be alarmed, and the failure can be eliminated by building up pressure again so that the braking returns to normal. In the event of a single-circuit leakage fault or a brake system failure fault, an alarm reminder will be issued through the alarm system to give a reminder.

[0049] The present application provides a vehicle braking system, which uses the above-mentioned vehicle brake failure detection and control method to detect and control vehicle braking. The detection and control method of the present application can be integrated into the electronic control unit of the braking system in a software manner and executed.

[0050] Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A method for detecting and controlling vehicle brake failure, characterized in that: Including, when the vehicle brake fails and the vehicle does not report a brake system fault; enter the brake caliper clearance fault processing process, determine whether it is a brake caliper clearance fault and perform fault elimination operations on the brake caliper clearance fault; Determining whether a brake caliper clearance fault exists and performing fault elimination operations for the brake caliper clearance fault include: actively building up pressure again and detecting the vehicle's deceleration after the pressure is built up. If the deceleration is greater than a set target threshold, it is determined that a brake caliper clearance fault exists and the caliper clearance is eliminated by actively building up pressure. Otherwise, it is determined that the brake caliper clearance fault does not exist. After determining that the fault is not a brake caliper clearance fault, the single-circuit leakage fault judgment process is entered. In this process: after closing either the LFRR circuit or the RFLR circuit, active pressure buildup is performed. If the deceleration is greater than the set target threshold, the closed circuit is judged to have a single-circuit leakage fault; If there is no leakage fault in the LFRR circuit and the RFLR circuit, it is determined that the brake system has failed, and the brake system directly brakes by actively building pressure; In the case of a single-circuit leakage fault, the boost valve of the leakage fault circuit is closed and then active pressure building braking is performed, or in the case of a brake system failure fault, braking is performed directly through active pressure building. If the deceleration of the entire vehicle reaches the deceleration corresponding to the brake pedal stroke, the active boost control is ended. Otherwise, the electronic control braking system will immediately request the electronic parking brake EPB and energy recovery for auxiliary braking.

2. The method for detecting and controlling vehicle brake failure according to claim 1, wherein: The vehicle brake failure judgment method includes: after detecting that the brake pedal is depressed, detecting the vehicle speed signal and converting it into vehicle deceleration, and judging that the vehicle brake failure occurs when the deceleration does not reach the vehicle deceleration value corresponding to the pedal stroke.

3. The method for detecting and controlling vehicle brake failure according to claim 1, wherein: In the case of a single-circuit leakage fault, the electronic control unit in the braking system controls the closure of the boost valve of the leakage fault circuit in the LFRR circuit and the RFLR circuit, and then actively builds pressure for braking.

4. A method for detecting and controlling vehicle brake failure according to any one of claims 1 to 3, characterized in that: When it is determined that the vehicle is in a single-circuit leakage fault or a brake system failure fault, an alarm reminder will be issued through the alarm system.

5. A vehicle braking system, characterized in that: The braking system uses the vehicle brake failure detection and control method as described in any one of claims 1 to 4 to perform brake detection and control on the vehicle.

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