A vehicle brake switch state abnormality monitoring and diagnosing method and system

Abstract

The application relates to the technical field of vehicle braking, and provides a vehicle braking switch state abnormality monitoring and diagnosis method and system, which comprises the following steps: monitoring that a braking switch of a vehicle is in a closed state at a current time, obtaining a target braking mode of a braking system of the vehicle at the current time in multiple braking modes; detecting a switch state of the braking switch and an actual pressure value of a brake fluid master cylinder of the braking system after the braking system executes the target braking mode; the switch state comprises a closed state and an open state; and determining whether the braking switch of the vehicle is in an abnormal state according to the switch state, the actual pressure value and the target braking mode. The accuracy of vehicle braking switch state abnormality monitoring and diagnosis can be improved.

Description

Technical Field

[0001] This application relates to the field of vehicle braking technology, and in particular to a method and system for monitoring and diagnosing abnormal states of vehicle brake switches. Background Technology

[0002] In modern vehicles, especially those with hybrid control functions of energy recovery and hydraulic braking, the vehicle control unit dynamically adjusts the braking strategy according to various operating conditions, which breaks the fixed physical relationship between the state of the brake pedal switch and the pressure signal of the braking system.

[0003] Traditional diagnostic methods often rely on a fixed physical relationship between brake switch signals and brake system pressure signals, making existing systems prone to misinterpreting normal vehicle behavior as brake switch malfunctions, thus affecting the accuracy and reliability of the diagnosis. Summary of the Invention

[0004] This application provides a method and system for monitoring and diagnosing abnormal states of vehicle brake switches, which can improve the accuracy of monitoring and diagnosing abnormal states of vehicle brake switches.

[0005] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application discloses a method for monitoring and diagnosing abnormal states of a vehicle brake switch, comprising the following steps: detecting that the vehicle's brake switch is in a closed state at the current moment, acquiring the target braking mode of the vehicle's braking system at the current moment from multiple braking modes; after the braking system executes the target braking mode, detecting the switch state and the actual pressure value of the brake fluid master cylinder of the braking system; the switch state includes a closed state and an open state; determining whether the vehicle's brake switch is in an abnormal state based on the switch state, the actual pressure value, and the target braking mode.

[0006] Further, determining whether the vehicle's brake switch is in an abnormal state based on the switch state, actual pressure value, and target braking mode includes: determining whether the switch state is closed; when the switch state is closed, obtaining a first correspondence; the first correspondence includes a one-to-one correspondence between multiple braking modes and multiple abnormal state assessment strategies; using the abnormal state assessment strategy corresponding to the target braking mode in the first correspondence as the target abnormal state assessment strategy; and determining whether the vehicle's brake switch is in an abnormal state based on the target abnormal state assessment strategy and the actual pressure value.

[0007] In some preferred embodiments, when the target braking mode is a pure kinetic energy recovery braking mode, the determination of whether the vehicle's brake switch is in an abnormal state is based on the target abnormal state assessment strategy and the actual pressure value, including: determining whether the actual pressure value is 0; if the actual pressure value is 0, determining that the vehicle's brake switch is in a normal state; if the actual pressure value is not 0, determining that the vehicle's brake switch is in an abnormal state.

[0008] As an optional solution, when the target braking mode is mechanical braking mode or hybrid braking mode, the vehicle's brake switch is determined to be in an abnormal state based on the target abnormal state assessment strategy and the actual pressure value, including: obtaining the expected pressure value of the brake fluid master cylinder of the braking system in the target braking mode; and determining whether the vehicle's brake switch is in an abnormal state based on the expected pressure value and the actual pressure value.

[0009] Furthermore, determining whether the vehicle's brake switch is in an abnormal state based on the expected pressure value and the actual pressure value includes: using the absolute value of the difference between the expected pressure value and the actual pressure value as the target difference value; determining that the vehicle's brake switch is in a normal state when the target difference value is less than a preset difference threshold; and determining that the vehicle's brake switch is in an abnormal state when the target difference value is greater than or equal to the preset difference threshold.

[0010] Based on the above, this application further proposes that, after determining whether the switch is in a closed state, when the switch is in an open state, the method further includes: obtaining a first degree of opening of the brake switch; when the first degree of opening is greater than a preset degree of opening threshold, obtaining the expected pressure value of the brake fluid master cylinder in the target braking mode; when the expected pressure value is 0 or the actual pressure value is 0, determining that the brake switch is in an abnormal state.

[0011] To improve the solution, the target braking mode of the vehicle's braking system at the current moment is obtained from multiple braking modes, including: obtaining the vehicle speed, the state of charge of the vehicle's power battery, the inclination of the road where the vehicle is located, and the second opening degree of the brake switch at the current moment; inputting the vehicle speed, state of charge, inclination, and second opening degree into a preset braking mode determination model to obtain the target braking information at the current moment; the target braking information includes the target braking mode.

[0012] As a technological improvement, the target braking information also includes the target braking force, and the expected pressure value of the brake fluid master cylinder of the braking system under the target braking mode is obtained, including: determining the initial pressure value of the brake fluid master cylinder based on the target braking force; obtaining the minimum identification pressure value of the pressure detection device that detects the pressure value of the brake fluid master cylinder; and determining the expected pressure value based on the minimum identification pressure value and the initial pressure value.

[0013] To optimize the structure, the expected pressure value is determined based on the minimum identification pressure value and the initial pressure value, including: determining whether the minimum identification pressure value is greater than the initial pressure value; if the minimum identification pressure value is greater than the initial pressure value, the expected pressure value is determined to be 0; if the minimum identification pressure value is less than or equal to the initial pressure value, the expected pressure value is determined to be the initial pressure value.

[0014] Secondly, this application also discloses a vehicle brake switch state abnormality monitoring and diagnosis system, including: an acquisition device and a processing device; the acquisition device is used to detect that the vehicle's brake switch is in a closed state at the current moment and acquire the target braking mode of the vehicle's braking system at the current moment among multiple braking modes; the processing device is used to detect the switch state and the actual pressure value of the brake fluid master cylinder of the braking system after the braking system executes the target braking mode; the switch state includes a closed state and an open state; the processing device is used to determine whether the vehicle's brake switch is in an abnormal state based on the switch state, the actual pressure value and the target braking mode.

[0015] Beneficial Effects: This application discloses a method for monitoring and diagnosing abnormal vehicle brake switch states. When the vehicle's brake switch is detected to be closed at the current moment, the target braking mode of the vehicle's braking system is obtained. After the braking system executes the target braking mode, the switch state and the actual pressure value of the brake fluid master cylinder are detected. Finally, based on the switch state, actual pressure value, and target braking mode, it is determined whether the vehicle's brake switch is in an abnormal state. This method effectively solves the problem in the prior art where, in modern vehicles, especially those with energy recovery and hydraulic braking hybrid control functions, the correlation between the brake switch state and the braking system pressure signal is broken, leading to traditional diagnostic methods easily misjudging normal vehicle behavior as brake switch failure, affecting diagnostic accuracy and reliability. By introducing the target braking mode as a judgment criterion, this application can comprehensively evaluate the brake switch state based on the vehicle's actual operating conditions and the dynamic adjustment of the braking strategy, avoiding misjudgments caused by the broken fixed physical correlation between the brake switch signal and the braking system pressure signal in traditional methods. This significantly improves the accuracy and reliability of monitoring and diagnosing abnormal brake switch states. Attached Figure Description

[0016] Figure 1 A flowchart illustrating a method for monitoring and diagnosing abnormal states of a vehicle brake switch provided in this application; Figure 2 A flowchart illustrating a method for monitoring and diagnosing abnormal states of a vehicle brake switch provided in this application; Figure 3 A flowchart illustrating a method for monitoring and diagnosing abnormal states of a vehicle brake switch provided in this application; Figure 4 This is a schematic diagram of the architecture of a vehicle brake switch status abnormality monitoring and diagnosis system provided in this application. Detailed Implementation

[0017] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0018] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0019] In modern vehicles, especially those with hybrid control functions of energy recovery and hydraulic braking, the vehicle control unit dynamically adjusts the braking strategy according to various operating conditions, which breaks the fixed physical relationship between the state of the brake pedal switch and the pressure signal of the braking system.

[0020] Traditional diagnostic methods often rely on a fixed physical relationship between brake switch signals and brake system pressure signals, making existing systems prone to misinterpreting normal vehicle behavior as brake switch malfunctions, thus affecting the accuracy and reliability of the diagnosis.

[0021] In this regard, such as Figure 1 As shown, this application proposes a method for monitoring and diagnosing abnormal states of vehicle brake switches, including the following steps: S101. If the vehicle's brake switch is detected to be closed at the current moment, the target braking mode of the vehicle's braking system at the current moment is obtained from multiple braking modes.

[0022] S102. After the braking system executes the target braking mode, detect the on / off status of the brake switch and the actual pressure value of the brake fluid master cylinder of the braking system.

[0023] Switch states include closed and open states.

[0024] S103. Determine whether the vehicle's brake switch is in an abnormal state based on the switch status, actual pressure value, and target braking mode.

[0025] This application, by comprehensively considering the switching status of the brake switch, the actual pressure value of the brake fluid master cylinder, and the vehicle's current target braking mode, can more accurately determine whether the brake switch is in an abnormal state, effectively avoiding the problem of misjudgment under specific working conditions by traditional methods, and significantly improving the accuracy and reliability of diagnosis.

[0026] To better understand the technical solution proposed in this application, some key terms involved will be explained first.

[0027] A "brake switch" is a sensor used to detect whether the driver has pressed the brake pedal. Its output signal is usually in a closed or open state, corresponding to whether the brake pedal has been pressed or not.

[0028] "Braking system" refers to the mechanism in a vehicle used for deceleration or stopping, and typically includes hydraulic braking systems and / or energy recovery braking systems.

[0029] "Actual pressure value of brake fluid master cylinder" refers to the actual hydraulic pressure inside the brake fluid master cylinder, which is usually detected in real time by a pressure sensor.

[0030] "Braking mode" refers to the braking strategy adopted by the vehicle's braking system under different operating conditions, such as pure kinetic energy recovery braking mode, mechanical braking mode, or hybrid braking mode.

[0031] "Target braking mode" refers to the braking strategy that the vehicle braking system determines at the current moment, based on various operating conditions (such as vehicle speed, battery state of charge, road inclination, brake switch opening degree, etc.), and is about to be executed or is being executed.

[0032] The core of the vehicle brake switch abnormality monitoring and diagnosis method of this application lies in comprehensively judging the abnormal state of the brake switch based on the switch status, the actual pressure value of the brake fluid master cylinder and the target braking mode.

[0033] Specifically, this method first detects that the vehicle's brake switch is in the closed state at the current moment. The closed state of the brake switch can be monitored in several ways. For example, it can be determined by reading the electrical signal of the brake switch; when the electrical signal reaches a preset closing threshold, the brake switch is considered to be in the closed state. Alternatively, it can be determined by detecting the displacement of the brake pedal using a mechanical sensor; when the displacement reaches a level that triggers the brake switch, the brake switch is considered to be in the closed state.

[0034] After detecting that the brake switch is in the closed state, it is necessary to obtain the target braking mode of the vehicle's braking system at the current moment from multiple braking modes. There are several ways to obtain the target braking mode. For example, the vehicle's control unit can use parameters such as the current vehicle speed, the state of charge (SOC) of the power battery, the inclination of the road, and the opening and closing degree of the brake switch to calculate and judge using a preset braking mode determination model, thereby determining the most suitable braking mode as the target braking mode. This model can be a rule-based expert system or a predictive model trained through machine learning.

[0035] After the braking system executes the target braking mode, it is necessary to detect the on / off status of the brake switch and the actual pressure value of the brake fluid master cylinder. The on / off status of the brake switch can be obtained again through the monitoring method described above to confirm whether it remains closed or has changed to an open state. The actual pressure value of the brake fluid master cylinder is usually detected in real time by a pressure sensor installed on the brake fluid master cylinder. The pressure sensor converts the hydraulic signal into an electrical signal and transmits it to the vehicle control unit for processing.

[0036] Finally, based on the detected switch status, actual pressure value, and target braking mode, it is determined whether the vehicle's brake switch is in an abnormal state. This judgment process is the key innovation of this application. For example, in pure kinetic energy recovery braking mode, even if the brake switch is in the closed state, the actual pressure value of the brake fluid master cylinder may be zero. If judged as abnormal using traditional methods, this would result in a false alarm. This application, however, judges the brake switch to be in a normal state based on the information that the target braking mode is pure kinetic energy recovery braking mode, combined with the fact that the actual pressure value is zero. In mechanical braking mode or hybrid braking mode, if the brake switch is in the closed state but the actual pressure value deviates significantly from the expected pressure value, it may be judged as an abnormal state.

[0037] The vehicle brake switch status anomaly monitoring and diagnosis method of this application breaks the fixed physical correlation between traditional brake switch signals and brake system pressure signals, and instead adopts a more intelligent and adaptable diagnostic logic. When the driver presses the brake pedal and the brake switch is detected to be in the closed state, the system no longer simply expects the brake fluid master cylinder pressure to rise immediately. Instead, it first obtains the current target braking mode of the vehicle braking system. This target braking mode is dynamically determined based on the vehicle's real-time operating conditions (such as vehicle speed, battery state of charge, road inclination, brake switch opening degree, etc.), and it reflects the optimal braking strategy selected by the vehicle control unit at the current moment.

[0038] After the braking system executes the target braking mode, it will again check the on / off state of the brake switch and the actual pressure value of the brake fluid master cylinder. At this point, the key is to comprehensively analyze these three pieces of information—the on / off state of the brake switch, the actual pressure value of the brake fluid master cylinder, and the target braking mode. For example, if the target braking mode is a pure kinetic energy recovery braking mode, then even if the brake switch is in the closed state, the actual pressure value of the brake fluid master cylinder may be zero, because in this case, the vehicle is mainly decelerated by electric motor reverse drag, and the hydraulic braking system may not be engaged. In this situation, the method of this application will determine that the brake switch is in a normal state based on the characteristics of the target braking mode, thereby avoiding the misjudgment of traditional methods under such conditions.

[0039] Conversely, if the target braking mode is mechanical braking or hybrid braking, and the brake switch is closed, the system expects the actual pressure value of the brake fluid master cylinder to reach a certain level. At this point, the system compares the actual pressure value with the expected pressure value to determine if the brake switch is malfunctioning. In this way, the method of this application can fully consider the complexity and diversity of modern vehicle braking systems, making the monitoring and diagnosis of brake switch malfunctions more accurate and reliable. The various technical features work together to construct an intelligent diagnostic system that can adapt to various braking conditions, effectively solving the problem of high false alarm rates in complex braking scenarios using traditional methods.

[0040] The vehicle brake switch status anomaly monitoring and diagnosis method proposed in this application represents a significant advancement and innovation compared to existing technologies. Traditional methods primarily rely on a fixed physical correlation between brake switch signals and brake system pressure signals for diagnosis. For example, when the brake switch is closed but the brake fluid master cylinder pressure does not rise, traditional methods typically conclude that the brake switch is faulty. This simple one-to-one correspondence is no longer accurate in reflecting the true operating state of modern vehicles, especially electric and hybrid vehicles, due to the widespread application of energy recovery braking and hydraulic braking hybrid control strategies.

[0041] The core innovation of this application lies in introducing the key parameter of "target braking mode" and comprehensively judging it in conjunction with the on / off state of the brake switch and the actual pressure value of the brake fluid master cylinder. After detecting that the brake switch is in the closed state at the current moment, the target braking mode of the vehicle's braking system at the current moment is first obtained. After the braking system executes the target braking mode, the on / off state of the brake switch and the actual pressure value of the brake fluid master cylinder are detected. Finally, based on these three factors, it is determined whether the brake switch is in an abnormal state.

[0042] This method effectively solves the misjudgment problem existing in the prior art. For example, in pure kinetic energy recovery braking mode, the driver presses the brake pedal, causing the brake switch to close. However, since the vehicle mainly recovers energy through the electric motor, the actual pressure value of the brake fluid master cylinder may be zero. Traditional methods would incorrectly judge this as a stuck or malfunctioning brake switch. However, the method of this application identifies the current target braking mode as pure kinetic energy recovery braking mode and, combined with the fact that the actual pressure value is zero, accurately determines that the brake switch is in a normal state.

[0043] Furthermore, in scenarios such as when the driver is applying the brakes, the brake switch may be closed, but the brake fluid master cylinder pressure may be very low. This application, through comprehensive analysis, can distinguish between this normal operation and actual malfunction, avoiding unnecessary fault reports. Therefore, the method of this application significantly improves the accuracy and reliability of brake switch anomaly monitoring and diagnosis, reduces the false alarm rate, and provides a more reliable guarantee for the safe operation of the vehicle.

[0044] Specifically, the steps described above for determining whether the vehicle's brake switch is in an abnormal state based on the switch status, actual pressure value, and target braking mode can be further refined as follows.

[0045] like Figure 2 As shown, according to the above-mentioned vehicle brake switch status abnormality monitoring and diagnosis method, the determination of whether the vehicle's brake switch is in an abnormal state is based on the switch status, actual pressure value, and target braking mode, including: S201. Determine whether the switch is in a closed state.

[0046] S202. When the switch is in the closed state, obtain the first correspondence.

[0047] The first correspondence includes a one-to-one correspondence between multiple braking modes and multiple abnormal state assessment strategies.

[0048] S203. The abnormal state assessment strategy corresponding to the target braking mode in the first correspondence is taken as the target abnormal state assessment strategy.

[0049] S204. Determine whether the vehicle's brake switch is in an abnormal state based on the target abnormal state assessment strategy and the actual pressure value.

[0050] The "first correspondence" refers to a pre-established mapping relationship that associates different braking modes with corresponding abnormal state assessment strategies. This correspondence can be stored in the memory of the vehicle's controller or diagnostic module, for example, in the form of a lookup table, database, or algorithmic logic. Through this correspondence, the system can dynamically select the most suitable abnormal state assessment strategy for the current target braking mode of the vehicle.

[0051] "Multiple braking modes" may include, but are not limited to, pure kinetic energy recovery braking mode, mechanical braking mode, and hybrid braking mode. The operating principle and expected performance of the braking system may differ significantly under each braking mode.

[0052] "Multiple abnormal state assessment strategies" refers to specific logic or algorithms designed for different braking modes to determine whether the brake switch is abnormal. For example, in pure kinetic energy recovery braking mode, the actual pressure value of the brake fluid master cylinder may be expected to be close to zero; while in mechanical braking mode or hybrid braking mode, the actual pressure value may match the expected pressure value.

[0053] The "target abnormal state assessment strategy" is a specific strategy selected from the first correspondence based on the current vehicle's target braking mode for this abnormal state assessment. Once the target abnormal state assessment strategy is determined, subsequent judgments will be strictly based on this strategy.

[0054] The solution proposed in this application introduces a first correspondence relationship and a target abnormal state evaluation strategy, making the determination process of brake switch abnormal states more refined and intelligent. When the brake switch is in the closed state, the system no longer uses a single general judgment logic, but first obtains the target abnormal state evaluation strategy that matches the current target braking mode from the preset first correspondence relationship. This ensures that under different braking conditions, such as pure kinetic energy recovery, mechanical braking, or hybrid braking, the evaluation criteria and logic most suitable for the characteristics of that condition can be used, thereby avoiding misjudgments or omissions caused by differences in braking modes.

[0055] Through the above technical solution, this application can significantly improve the accuracy and reliability of monitoring and diagnosing abnormal vehicle brake switch states. By mapping braking modes to abnormal state assessment strategies, the system can dynamically adjust the diagnostic logic according to the actual operating conditions of the vehicle, thereby avoiding diagnostic biases caused by using inappropriate assessment standards in different braking modes. This helps to more accurately identify potential brake switch faults, reduce unnecessary maintenance or safety hazards caused by misjudgments, and thus improve the overall safety performance of the vehicle and the user experience.

[0056] like Figure 3 As shown, this application further proposes a step for determining whether the vehicle's brake switch is in an abnormal state based on a target abnormal state assessment strategy and actual pressure value when the target braking mode is a pure kinetic energy recovery braking mode. Specifically, this includes: S301. Determine if the actual pressure value is 0.

[0057] S302. If the actual pressure value is 0, it is determined that the vehicle's brake switch is in normal condition.

[0058] S303. If the actual pressure value is not 0, it is determined that the vehicle's brake switch is in an abnormal state.

[0059] Specifically, pure regenerative braking mode refers to a braking method where the vehicle primarily uses the reverse drag effect of the electric motor to convert and store the vehicle's kinetic energy into electrical energy, thereby achieving vehicle deceleration. In this mode, the vehicle's hydraulic braking system typically does not participate in braking or only assists in braking in emergencies. Therefore, when the brake switch is closed and the vehicle is in pure regenerative braking mode, the actual pressure value of the brake fluid master cylinder should ideally remain at 0. The actual pressure value refers to the hydraulic pressure value in the brake fluid master cylinder detected by the pressure sensor. If the actual pressure value is not 0, it indicates that there may be abnormal intervention in the hydraulic braking system, such as brake valve sticking, pressure sensor failure, or brake system malfunction. In this case, the state of the brake switch should be determined as abnormal. Conversely, if the actual pressure value is indeed 0, it indicates that the hydraulic braking system has not intervened, and the working state of the brake switch meets the expectations of pure regenerative braking mode, thus being determined as normal.

[0060] This application's solution addresses the lack of refined anomaly assessment strategies across different braking modes by establishing specific anomaly assessment logic for the pure kinetic energy recovery braking mode. In pure kinetic energy recovery braking mode, the vehicle's braking energy is primarily recovered through the electric motor, and the hydraulic braking system should generally not generate pressure. Therefore, when the brake switch is detected to be closed and the vehicle is in pure kinetic energy recovery braking mode, determining whether the actual pressure value of the brake fluid master cylinder is 0 directly and effectively identifies any anomalies in the brake switch and its related hydraulic system. If the actual pressure value is not 0, it means that the hydraulic braking system has generated pressure when it should not have intervened, which could indicate anomalies such as brake switch signal misinterpretation, brake system actuator malfunction, or incorrect pressure sensor readings. This mode-characteristic-based judgment mechanism makes anomaly diagnosis more accurate.

[0061] Through the above technical solution, this application provides a highly specific anomaly diagnosis method for pure kinetic energy recovery braking mode. This method can accurately identify the abnormal situation in this specific braking mode where the brake switch is closed but the brake fluid master cylinder exhibits a non-zero actual pressure value, thus avoiding potential misjudgments or missed judgments that may occur due to the lack of hydraulic system intervention in pure kinetic energy recovery braking mode. This significantly improves the accuracy and reliability of monitoring and diagnosing abnormal vehicle brake switch status, helping to promptly detect and resolve potential braking system faults and ensure driving safety.

[0062] In some preferred embodiments, a specific example is given below. Assume that while the vehicle is in motion, the driver depresses the brake pedal, causing the brake switch to close. Based on information such as the current vehicle speed and the state of charge of the battery, the vehicle's braking system determines that the current target braking mode is pure regenerative braking mode.

[0063] In this scenario, the braking system performs pure kinetic energy recovery braking. Subsequently, the system detects the on / off status of the brake switch and the actual pressure value of the brake fluid master cylinder.

[0064] Specifically, if the actual pressure value of the brake fluid master cylinder is detected to be 0, the judgment logic of this embodiment determines that the vehicle's brake switch is in a normal state. This indicates that although the driver presses the brake pedal, the hydraulic braking system does not intervene, and braking is entirely completed by the kinetic energy recovery system, which is in line with the expectation of the pure kinetic energy recovery braking mode.

[0065] However, if the actual pressure value of the brake fluid master cylinder is not detected to be zero, for example, the judgment logic of this embodiment determines that the vehicle's brake switch is in an abnormal state. This may mean that the brake fluid master cylinder pressure sensor is faulty, or that the hydraulic braking system has intervened unnecessarily in pure kinetic energy recovery braking mode, such as brake valve sticking, resulting in abnormal pressure. In this way, the system can detect and report such abnormalities in a timely manner for further inspection and maintenance.

[0066] In some embodiments described above, this application proposes a method for determining whether a brake switch is in an abnormal state based on its switch state, actual pressure value, and target braking mode. When the switch is in a closed state, a target abnormal state assessment strategy is acquired, and a judgment is made based on this strategy and the actual pressure value. However, in practical applications, when the target braking mode is a mechanical braking mode or a hybrid braking mode, relying solely on a general abnormal state assessment strategy may not adequately consider the actual operating characteristics of the brake fluid master cylinder under these modes, resulting in inaccurate or untimely judgments of the brake switch's abnormal state. Failure to address this issue may affect vehicle safety and diagnostic reliability during critical braking modes.

[0067] In response, this application further proposes a method for determining whether the vehicle's brake switch is in an abnormal state based on the aforementioned target abnormal state assessment strategy and actual pressure value when the target braking mode is a mechanical braking mode or a hybrid braking mode. The method includes the following steps: When the target braking mode is mechanical braking mode or hybrid braking mode, the system determines whether the vehicle's brake switch is in an abnormal state based on the target abnormal state assessment strategy and the actual pressure value, including: Obtain the expected pressure value of the brake fluid master cylinder in the braking system under the target braking mode; determine whether the vehicle's brake switch is in an abnormal state based on the expected pressure value and the actual pressure value.

[0068] Specifically, when a vehicle's braking system is in mechanical braking mode or hybrid braking mode, the generation of braking force typically involves the pressure build-up in the brake fluid master cylinder. In this scenario, the closed state of the brake switch should be directly related to the pressure generated in the brake fluid master cylinder. The expected pressure value refers to the theoretical pressure value that the brake fluid master cylinder should reach under the current target braking mode, assuming the brake switch functions normally and the braking system responds normally. This expected pressure value can be calculated or obtained from tables based on vehicle operating parameters (such as vehicle speed, brake pedal travel or force, braking demand, etc.) and the design characteristics of the braking system. The actual pressure value refers to the actual pressure in the brake fluid master cylinder detected in real time by a pressure sensor. By comparing the expected pressure value with the actual pressure value, the functional status of the brake switch and the braking system's response to the brake switch signal can be effectively evaluated.

[0069] This application's solution addresses the issue of insufficient diagnostic accuracy that may result from relying solely on general anomaly assessment strategies in mechanical or hybrid braking modes by introducing a predicted pressure value for the brake fluid master cylinder and comparing it with the actual pressure value. In these braking modes, the closure of the brake switch directly drives the hydraulic braking system; therefore, pressure changes in the brake fluid master cylinder are a key indicator of the brake switch's functionality. When the brake switch is closed and the target braking mode is mechanical or hybrid braking, the braking system should establish corresponding hydraulic pressure in the brake fluid master cylinder. By acquiring and utilizing the predicted pressure value, a clear reference benchmark can be established. If the actual detected pressure differs significantly from this predicted pressure value, it indicates a potential anomaly in the brake switch or its associated braking system response. For example, the brake switch may be closed but fail to effectively trigger the hydraulic system, or the hydraulic system itself may be faulty, preventing proper pressure establishment. Thus, this method can more accurately pinpoint the abnormal state of the brake switch.

[0070] Through the above technical solution, this application can significantly improve the diagnostic accuracy of abnormal states of vehicle brake switches in mechanical braking mode or hybrid braking mode. This method, by directly monitoring the actual pressure of the brake fluid master cylinder and comparing it with the expected pressure, can promptly detect potential brake switch faults, such as false alarms of brake switch closure or the braking system not responding as expected after closure. This helps improve vehicle braking safety, avoids the risk of brake performance degradation or failure due to brake switch malfunctions, and thus provides drivers with more reliable braking protection.

[0071] In some preferred embodiments, it is assumed that the vehicle is currently in a hybrid braking mode and the brake switch is detected to be closed. First, the system calculates or looks up the expected pressure value of the brake fluid master cylinder based on the current vehicle operating parameters (e.g., vehicle speed, driver braking demand, etc.) and the characteristics of the hybrid braking mode; for example, the expected pressure value is 5 MPa. Then, the system detects the current actual pressure value using a pressure sensor installed on the brake fluid master cylinder. If the actual pressure value is detected as 0.5 MPa, significantly lower than the expected pressure value of 5 MPa, the system determines that the vehicle's brake switch is in an abnormal state based on the difference between the expected and actual pressure values. This may mean that although the brake switch indicates it is closed, it has failed to effectively drive the brake fluid master cylinder to build sufficient pressure, or that the brake fluid master cylinder itself is faulty. Conversely, if the actual pressure value is detected as 4.8 MPa, very close to the expected pressure value of 5 MPa, the system determines that the brake switch is in a normal state.

[0072] In some of the embodiments described above in this application, it is proposed to determine whether the vehicle's brake switch is in an abnormal state based on the expected pressure value and the actual pressure value. However, in the implementation process, there is a lack of specific implementation details on how to quantify the difference between the expected pressure value and the actual pressure value and use it as the basis for judging the abnormal state of the brake switch, which may lead to insufficient accuracy in the judgment.

[0073] In response, this application further proposes a specific method for determining whether the brake switch of the vehicle is in an abnormal state based on the expected pressure value and the actual pressure value under the aforementioned mechanical braking mode or mixed braking mode. This method includes the following steps: The absolute value of the difference between the expected pressure value and the actual pressure value is taken as the target difference value; when the target difference value is less than the preset difference threshold, the brake switch of the vehicle is determined to be in a normal state; when the target difference value is greater than or equal to the preset difference threshold, the brake switch of the vehicle is determined to be in an abnormal state.

[0074] Specifically, the aforementioned target difference refers to the absolute deviation between the expected pressure value and the actual pressure value. Its purpose is to quantify the degree of deviation between the actual pressure in the brake fluid master cylinder and the system's expected ideal pressure when the braking system executes the target braking mode. The preset difference threshold can be understood as the upper limit of the allowable pressure deviation range. This threshold is typically determined through extensive experimental data, vehicle calibration, and safety regulations to ensure that minor fluctuations under normal operating conditions are not misjudged as abnormal, while simultaneously identifying significant deviations that may lead to safety hazards. In practical applications, when the calculated target difference is less than the preset difference threshold, it indicates that the actual pressure is basically consistent with the expected pressure, and the brake switch is judged to be in a normal state. Conversely, if the target difference is greater than or equal to the preset difference threshold, it means that there is an unacceptable deviation between the actual pressure and the expected pressure, and the brake switch is judged to be in an abnormal state.

[0075] This application's solution effectively solves the problem of accurately and quantitatively judging the abnormal state of the brake switch in mechanical braking mode or hybrid braking mode by introducing a comparison mechanism between the target difference and a preset difference threshold. It is precisely because the absolute value of the difference between the expected and actual pressure values ​​is calculated and compared with a preset allowable deviation threshold that the system can objectively assess whether the pressure output of the brake fluid master cylinder meets expectations. This judgment method based on quantitative comparison can filter out unavoidable minor fluctuations during system operation, while accurately capturing significant pressure deviations that may indicate brake switch failure, thereby avoiding the ambiguity of subjective judgment and improving the accuracy of abnormal state identification.

[0076] Through the above technical solution, this application provides a more accurate and reliable method for diagnosing abnormal brake switch conditions. This method, by setting clear quantitative standards (i.e., preset difference thresholds), effectively distinguishes between normal operating fluctuations and pressure deviations caused by actual faults, significantly reducing the risk of false alarms and missed alarms. Therefore, it not only improves the intelligence level of vehicle braking system monitoring but also provides drivers and vehicle maintenance personnel with more accurate fault information, thereby ensuring driving safety.

[0077] In some preferred embodiments, a specific example is given below. Assume that the vehicle is in mechanical braking mode, and the system calculates the expected pressure value of the brake fluid master cylinder to be 50 bar. Simultaneously, the actual pressure value detected by the pressure detection device is 48 bar. In this case, the absolute value of the difference between the expected pressure value of 50 bar and the actual pressure value of 48 bar is taken as the target difference value, i.e., |50-48|=2 bar. If the preset difference threshold is set to 3 bar, since the target difference value of 2 bar is less than the preset difference threshold of 3 bar, the system will determine that the vehicle's brake switch is in a normal state. As another specific implementation, if the actual pressure value is 45 bar, then the target difference value is |50-45|=5 bar. Since the target difference value of 5 bar is greater than or equal to the preset difference threshold of 3 bar, the system will determine that the vehicle's brake switch is in an abnormal state. In this way, the operating state of the brake switch can be accurately determined based on the degree of deviation between the actual pressure and the expected pressure.

[0078] In some of the above embodiments, the abnormal monitoring and diagnosis method for the vehicle brake switch status, after determining the switch's on / off state, primarily performs a detailed anomaly assessment for the case where the brake switch is in the closed state. However, when the brake switch is detected as open, relying solely on simple status judgment may not be sufficient to comprehensively and effectively diagnose potential abnormalities in the brake switch, especially when the driver actually depresses the brake pedal but the brake switch fails to respond correctly. If this problem is not addressed, faults in the brake switch's open state may not be identified in a timely and accurate manner, thereby affecting vehicle braking safety.

[0079] In response, this application further proposes a method to more comprehensively and accurately determine whether the brake switch is in an abnormal state when the brake switch is in the open state by combining the opening degree of the brake switch, the expected pressure value and the actual pressure value.

[0080] After determining whether the switch is in a closed state, the method further includes the following steps when the switch is in an open state: Obtain the first opening degree of the brake switch; when the first opening degree is greater than the preset opening degree threshold, obtain the expected pressure value of the brake fluid master cylinder in the target braking mode; when the expected pressure value is 0 or the actual pressure value is 0, determine that the brake switch is in an abnormal state.

[0081] Specifically, in the above method, when the brake switch is determined to be in the off state, the system further acquires the first degree of opening of the brake switch. The first degree of opening can be understood as the depth of the brake pedal corresponding to the brake switch, reflecting the degree to which the driver has pressed the brake pedal. This degree of opening can be detected in real time by a sensor installed on the brake pedal or brake switch. The preset opening threshold is a pre-set critical value used to distinguish between slight contact and effective pressing of the brake pedal. When the first degree of opening is greater than the preset threshold, it indicates that the driver has performed a substantial braking operation; at this point, even if the brake switch is in the off state, there should be a corresponding braking response. Based on this, the system acquires the expected pressure value of the brake fluid master cylinder under the target braking mode.

[0082] The expected pressure value refers to the theoretical pressure value that the brake fluid master cylinder should reach under the current target braking mode and the driver's braking demand. This expected pressure value can be calculated using a preset model or algorithm based on factors such as the vehicle's operating status, the driver's braking intention, and the braking mode. Furthermore, when the expected pressure value is 0 or the actual pressure value is 0, the system will determine that the brake switch is in an abnormal state. Specifically, if the driver's brake pedal opening degree exceeds a preset threshold (i.e., the first opening degree is greater than the preset opening degree threshold), but the brake switch remains in the open state, and the expected or actual pressure value of the brake fluid master cylinder is 0, it indicates that there may be an abnormality in the braking system. For example, the brake switch may be stuck in the open position, or the brake fluid master cylinder itself may be faulty, causing the expected braking pressure to be unable to be generated or detected even if the driver presses the brake pedal.

[0083] This application's solution, by introducing a judgment on the opening degree of the brake switch in the off state, and combining it with expected and actual pressure values, enables a more comprehensive diagnosis of brake switch anomalies. In the basic solution, when the brake switch is in the off state, only a simple state judgment may be performed. However, with this solution, even if the brake switch is in the off state, if the driver's brake pedal opening degree has reached the effective braking level (i.e., the first opening degree is greater than the preset opening degree threshold), the system will further check the expected and actual pressure values ​​of the brake fluid master cylinder. If the expected or actual pressure value is 0, it indicates that the brake switch may have a mechanical fault (such as sticking) or an electrical fault, causing it to fail to respond correctly to the driver's braking operation, thus timely detecting and diagnosing potential anomalies of the brake switch in the off state. This mechanism avoids missed diagnoses that may be caused by judging solely by the switch state, improving the accuracy and coverage of anomaly diagnosis.

[0084] Through the above technical solution, this application effectively overcomes the shortcomings of existing technologies in diagnosing abnormalities when the brake switch is in the open state. Especially when the brake switch indicates an open state, but the driver has actually pressed the brake pedal and reached a certain opening degree, it can accurately identify problems such as brake switch jamming, sensor malfunction, or wiring abnormalities by comparing the expected pressure value with the actual pressure value to see if they are zero. This significantly improves the comprehensiveness and accuracy of vehicle brake switch anomaly monitoring and diagnosis, avoiding safety hazards caused by failure to detect brake switch malfunctions in the open state, thereby improving vehicle driving safety.

[0085] In some preferred embodiments, assuming the vehicle is in motion and the driver depresses the brake pedal, the brake switch is detected as being in an open state. The system first obtains the first degree of opening of the brake switch, for example, detecting a brake pedal travel of 15mm. A preset opening threshold is set to 5mm. Since 15mm is greater than 5mm, the system determines that the driver has performed a valid braking operation. Next, the system calculates the expected pressure value of the brake fluid master cylinder based on the current target braking mode (e.g., pure mechanical braking mode), assuming it is 5MPa. Simultaneously, the system detects that the actual pressure value of the brake fluid master cylinder is 0MPa. Since the actual pressure value is 0, the system, according to the logic of this scheme, determines that the brake switch is in an abnormal state. In this case, even if the brake switch is displayed as open, because the driver has depressed the brake pedal and no expected pressure has been generated, the system can promptly diagnose that the brake switch may be stuck or that the braking system is malfunctioning, thereby issuing a warning to the driver or taking other safety measures.

[0086] Specifically, in the above-mentioned method for monitoring and diagnosing abnormal vehicle brake switch status, the step of obtaining the target braking mode of the vehicle's braking system at the current moment can be further refined.

[0087] The system acquires the target braking mode of the braking system of a vehicle with multiple braking modes at the current moment, including: acquiring the vehicle speed, the state of charge of the vehicle's power battery, the inclination of the road where the vehicle is located, and the second opening degree of the brake switch at the current moment; inputting the vehicle speed, state of charge, inclination, and second opening degree into a preset braking mode determination model to obtain the target braking information at the current moment; the target braking information includes the target braking mode.

[0088] Specifically, vehicle speed refers to the vehicle's current speed, which can be monitored and acquired in real time by the vehicle's speed sensor. The state of charge (SOC) of the power battery refers to the ratio of the remaining charge to the total charge, reflecting the battery's available energy, and is typically calculated and managed by the battery management system (BMS). The inclination of the road the vehicle is on refers to the gradient information of the current road segment, such as uphill, downhill, or flat road, which can be obtained through the vehicle's inertial measurement unit (IMU) or in conjunction with high-precision map data. The second degree of brake pedal engagement refers to the depth or angle at which the brake pedal is depressed, reflecting the driver's braking intention and required braking intensity, and is typically detected by the brake pedal position sensor.

[0089] The preset braking mode determination model can be understood as a pre-trained algorithm model, such as a model built based on machine learning, fuzzy logic, or rule bases. The purpose of this model is to intelligently determine and output the most suitable braking mode based on the input vehicle operating state parameters. In practical applications, this model can be stored in the vehicle's electronic control unit (ECU) and invoked in real time during vehicle operation. The target braking information refers to the comprehensive information output by the preset braking mode determination model, which includes at least the target braking mode. The target braking mode refers to the braking strategy that the braking system should adopt under the current vehicle operating conditions, such as pure kinetic energy recovery braking mode, mechanical braking mode, or hybrid braking mode.

[0090] The proposed solution comprehensively and accurately reflects the vehicle's current operating conditions and the driver's braking needs by considering multiple key parameters, including vehicle speed, battery state of charge, road inclination, and the second opening degree of the brake switch. These parameters are input into a preset braking mode determination model, which, based on its internal logic or training results, intelligently analyzes the complex relationships between these input parameters to output the braking mode most suitable for the current operating conditions.

[0091] For example, when the vehicle speed is high and the battery's state of charge is low, the system may prioritize regenerative braking to replenish the battery. Conversely, when the road gradient is significant or the second opening degree of the brake switch indicates a strong braking demand, the system may prefer mechanical braking or hybrid braking to ensure effective braking. Thus, by inputting multi-dimensional parameters and using intelligent model judgment, errors that might arise from judging a single parameter can be avoided, making the determination of the target braking mode more accurate and reasonable.

[0092] By employing the aforementioned technical solution, and considering more comprehensive vehicle operating parameters and driver intent when determining the target braking mode, the determined target braking mode can more accurately match actual operating conditions. This not only helps improve the responsiveness and adaptability of the braking system but also provides a more precise benchmark for subsequent monitoring and diagnosis of abnormal brake switch states, thereby enhancing the accuracy and reliability of diagnosis. Furthermore, mode determination through intelligent models can also optimize braking energy recovery efficiency or braking safety, further improving the overall performance of the vehicle.

[0093] In some embodiments described above in this application, under certain braking modes, it is necessary to obtain the expected pressure value of the brake fluid master cylinder for abnormal condition assessment. However, in practical applications, simply obtaining the expected pressure value without a precise determination mechanism may lead to a deviation between the expected pressure value and the actual situation, thereby affecting the accuracy of brake switch abnormal condition diagnosis.

[0094] In this regard, this application further proposes that the aforementioned target braking information also includes target braking force, and that obtaining the expected pressure value of the brake fluid master cylinder in the aforementioned braking system under the aforementioned target braking mode includes: The initial pressure value of the brake fluid master cylinder is determined based on the target braking force; the minimum identification pressure value of the pressure detection device for detecting the pressure value of the brake fluid master cylinder is obtained; and the expected pressure value is determined based on the minimum identification pressure value and the initial pressure value.

[0095] Specifically, the aforementioned target braking force refers to the total braking force that the vehicle needs to generate under the current braking mode. It can be calculated by the aforementioned preset braking mode determination model based on the vehicle's operating state parameters (such as vehicle speed, state of charge, tilt, and the degree of opening and closing of the brake switch). This target braking force is a quantitative representation of the braking effect that the vehicle's braking system should achieve under the current operating conditions.

[0096] Determining the initial pressure value of the brake fluid master cylinder based on the target braking force involves converting the target braking force into the hydraulic pressure value that the brake fluid master cylinder should produce under ideal conditions, using a physical model or preset mapping relationship of the vehicle braking system. For example, the initial pressure of the master cylinder matching the target braking force can be obtained through inverse calculations using factors such as brake pedal travel, master cylinder pressure, brake booster gain, and wheel braking force distribution. The purpose is to provide a theoretical benchmark for determining subsequent expected pressure values.

[0097] In practical applications, the minimum recognizable pressure value of the pressure detection device for measuring the pressure of the brake fluid master cylinder refers to the minimum effective pressure value that the sensor or device used to measure the brake fluid master cylinder pressure can recognize. Any pressure below this minimum recognizable pressure value may be interpreted as zero by the sensor or cannot be measured accurately. The purpose is to account for the accuracy limitations of actual measuring equipment and ensure that the determined expected pressure value can be effectively recognized by the actual detection device.

[0098] Therefore, determining the expected pressure value based on the aforementioned minimum identification pressure value and the aforementioned initial pressure value means comprehensively considering both the theoretical initial pressure value and the accuracy limitations of the actual measuring equipment to determine a more reasonable and realistic expected pressure value. This process aims to ensure that the expected pressure value reflects both the vehicle's braking requirements and the actual measurement capabilities of the sensors.

[0099] The solution proposed in this application takes the target braking force contained in the target braking information as input, and first calculates the initial pressure value of the brake fluid master cylinder based on the target braking force, thereby providing a theoretical benchmark for the expected pressure value based on the actual braking demand of the vehicle and the physical model.

[0100] Furthermore, considering the measurement accuracy limitations of actual pressure detection devices, a minimum identification pressure value is introduced. By comprehensively considering the initial pressure value and the minimum identification pressure value, an expected pressure value that both meets braking requirements and can be effectively detected in practice can be determined. This method avoids the inaccuracies that may arise from simply obtaining the expected pressure value, making the expected pressure value closer to the actual measurable range, thereby improving the accuracy and reliability of subsequent brake switch abnormality diagnosis.

[0101] Through the above technical solution, this application can accurately calculate the expected pressure value of the brake fluid master cylinder based on more comprehensive vehicle operating information (i.e., target braking force). Compared with a rough judgment relying solely on the braking mode, this solution, by introducing the target braking force and considering the minimum identification pressure value of the pressure detection device, makes the determination process of the expected pressure value more refined and intelligent. Therefore, when comparing the actual pressure value with the expected pressure value subsequently, the accuracy of brake switch abnormality diagnosis can be significantly improved, effectively reducing false alarms or missed alarms, thereby enhancing the safety and reliability of the vehicle braking system.

[0102] In some preferred embodiments, assuming that at a certain moment, the aforementioned preset braking mode determination model calculates that the current target braking mode is a hybrid braking mode based on the vehicle speed, state of charge, tilt, and the second opening degree of the brake switch, and that the target braking force included in the target braking information is 1000N. According to the physical model of the vehicle braking system, the 1000N target braking force is converted into an initial pressure value of the brake fluid master cylinder, for example, calculated to be 5MPa. Simultaneously, the minimum identification pressure value of the pressure detection device used to detect the brake fluid master cylinder pressure is obtained as 0.2MPa. Based on this, the initial pressure value of 5MPa is compared with the minimum identification pressure value of 0.2MPa. Since 5MPa is greater than 0.2MPa, the expected pressure value is determined to be 5MPa. In another case, if the target braking force is smaller, and the calculated initial pressure value is 0.1MPa, while the minimum identification pressure value remains 0.2MPa, then since 0.1MPa is less than 0.2MPa, the expected pressure value will be determined to be 0MPa. This reflects that in actual measurement, values ​​below the minimum identification pressure may not be effectively detected. In this way, the determination of the expected pressure value fully considers both theoretical requirements and practical measurement limitations, providing a solid foundation for subsequent anomaly diagnosis.

[0103] In some embodiments described above, the initial pressure value of the brake fluid master cylinder is determined based on the target braking force, and the expected pressure value is determined by combining this with the minimum identification pressure value of the pressure detection device that detects the pressure value of the brake fluid master cylinder. However, in practical applications, if the initial pressure value is lower than the minimum identification pressure value of the pressure detection device, directly using the initial pressure value as the expected pressure value may result in a discrepancy between the expected pressure value and the actual detectable pressure value, thereby affecting the accuracy of the judgment of abnormal brake switch status.

[0104] In response, this application further proposes a specific method for determining the expected pressure value based on the minimum identification pressure value and the initial pressure value, so as to improve the accuracy of the expected pressure value determination.

[0105] Specifically, determining the expected pressure value based on the minimum identification pressure value and the initial pressure value includes the following steps: Determine if the minimum identification pressure value is greater than the initial pressure value; if the minimum identification pressure value is greater than the initial pressure value, determine the expected pressure value to be 0; if the minimum identification pressure value is less than or equal to the initial pressure value, determine the expected pressure value to be the initial pressure value.

[0106] The minimum detection pressure value refers to the minimum pressure value that the pressure detection device can accurately identify and output. Pressures below this value may not be effectively detected or may be considered zero. The initial pressure value is the brake fluid master cylinder pressure value calculated based on the target braking force theory. The expected pressure value is the brake fluid master cylinder pressure value that the system expects under the current braking mode, taking into account the actual capabilities of the pressure detection device.

[0107] The solution proposed in this application ensures the rationality and measurability of the expected pressure value by introducing a judgment on the minimum identification pressure value. Specifically, when the minimum identification pressure value is determined to be greater than the initial pressure value, it means that the theoretical pressure value calculated based on the target braking force is lower than the detection limit of the pressure detection device. In this case, even if there is a tiny theoretical pressure, the pressure detection device cannot accurately identify it, and the actual measurement result will approach zero.

[0108] Therefore, setting the expected pressure value to 0 more accurately reflects the detectable pressure state of the brake fluid master cylinder under current operating conditions. Conversely, if the minimum detection pressure value is less than or equal to the initial pressure value, it indicates that the initial pressure value is within the effective detection range of the pressure detection device. In this case, directly using the initial pressure value as the expected pressure value is reasonable and accurate. It is precisely because of this judgment mechanism based on the actual detection capability of the sensor that the determination of the expected pressure value is more consistent with the actual situation, avoiding the deviation between the theoretical value and the actual measurable value.

[0109] Through the above technical solution, this application ensures that the determined expected pressure value is actually measurable and meaningful, thereby significantly improving the accuracy and reliability of vehicle brake switch status anomaly monitoring and diagnosis. This solution effectively avoids misjudgments caused by the minimum recognition limit of the pressure detection device. For example, if the theoretical initial pressure value is extremely low but the sensor cannot detect it, using it as the expected pressure value may lead to false alarms when compared with the actually measured zero pressure. By setting the expected pressure value below the minimum recognition pressure value to 0, this application can more accurately reflect the actual operating state of the braking system, thereby improving the robustness of the entire anomaly monitoring and diagnosis system.

[0110] In some preferred embodiments, a specific example is given below.

[0111] Assume the minimum recognition pressure of the pressure detection device equipped with the vehicle's braking system is 1.0 MPa.

[0112] Scenario 1: Under a certain braking condition, the initial pressure of the brake fluid master cylinder, calculated based on the target braking force, is 0.5 MPa. At this point, the system will determine whether the minimum detection pressure value of 1.0 MPa is greater than the initial pressure value of 0.5 MPa. Since 1.0 MPa is greater than 0.5 MPa, the system will determine the expected pressure value to be 0. This means that although a pressure of 0.5 MPa theoretically exists, the system will treat it as no pressure output because the sensor cannot effectively detect it.

[0113] Scenario 2: Under another braking condition, the initial pressure of the brake fluid master cylinder calculated based on the target braking force is 2.0 MPa. In this case, the system will determine whether the minimum detection pressure value of 1.0 MPa is greater than the initial pressure value of 2.0 MPa. Since 1.0 MPa is not greater than 2.0 MPa, the system will determine the expected pressure value as the initial pressure value of 2.0 MPa. This means that the theoretically calculated pressure value is within the sensor's detection range, and the system expects to detect a pressure of 2.0 MPa.

[0114] Through the examples of the two scenarios described above, the solution proposed in this application can flexibly and accurately determine the expected pressure value based on the actual performance of the pressure detection device, providing a reliable basis for subsequent abnormal state judgment.

[0115] This application also discloses a vehicle brake switch state abnormality monitoring and diagnosis system, including: an acquisition device and a processing device; the acquisition device is used to detect that the vehicle's brake switch is in a closed state at the current moment and acquire the target braking mode of the vehicle's braking system at the current moment; the processing device is used to detect the switch state and the actual pressure value of the brake fluid master cylinder of the braking system after the braking system executes the target braking mode; the switch state includes a closed state and an open state; the processing device is used to determine whether the vehicle's brake switch is in an abnormal state based on the switch state, the actual pressure value and the target braking mode.

[0116] This system establishes a complete and intelligent monitoring and diagnostic system by assigning the functions of monitoring the brake switch status, acquiring the target braking mode, detecting the brake switch status and the actual pressure value of the brake fluid master cylinder, and finally judging abnormal states, either separately or jointly, to the acquisition and processing devices. This systematic design effectively solves the problem of misjudgment caused by the disruption of the fixed physical correlation between the brake switch signal and the brake system pressure signal under the complex braking conditions of modern vehicles using traditional diagnostic methods, significantly improving the accuracy and reliability of the diagnosis.

[0117] To better understand the technical solution proposed in this application, some key terms are explained first. "Brake switch" refers to a sensor used to detect whether the driver has pressed the brake pedal; its output signal is typically a closed or open state, corresponding to the brake pedal being pressed or not, respectively. "Brake system" refers to the mechanism used by a vehicle to decelerate or stop, typically including a hydraulic braking system and / or an energy recovery braking system. "Actual pressure value of the brake fluid master cylinder" refers to the actual hydraulic pressure inside the brake fluid master cylinder, which is usually detected in real time by a pressure sensor. "Brake mode" refers to the braking strategy adopted by the vehicle's braking system under different operating conditions, such as pure kinetic energy recovery braking mode, mechanical braking mode, or hybrid braking mode. "Target braking mode" refers to the braking strategy that the vehicle's braking system determines at the current moment, based on various operating conditions (such as vehicle speed, battery state of charge, road inclination, brake switch opening degree, etc.), and is about to be executed or is currently being executed.

[0118] The specific steps and principles of the vehicle brake switch state anomaly monitoring and diagnosis method have been described in the above embodiments, and will not be repeated here. It should be emphasized that the vehicle brake switch state anomaly monitoring and diagnosis system proposed in this application, by introducing an acquisition device and a processing device, concretizes the above method steps into executable hardware or software modules.

[0119] Specifically, the acquisition device can be implemented as a standalone or integrated module within the vehicle control unit (ECU), containing interface circuitry for receiving brake switch signals, a microcontroller for processing sensor data, and memory and a processor for executing braking mode determination algorithms. For example, the acquisition device could be a dedicated sensor interface unit responsible for acquiring and digitizing the electrical signals from the brake switch in real time. Simultaneously, this device can receive data from other sensors (such as vehicle speed sensors, battery management systems, tilt sensors, etc.) via the vehicle's internal communication network (such as the CAN bus) and utilize built-in algorithmic models (e.g., rule-based decision tree models or pre-trained neural network models) to calculate and output the current target braking mode. Alternatively, the acquisition device's function can be undertaken by specific software tasks within the vehicle's central gateway or powertrain control module (PCM), programmed to monitor the brake switch status and acquire the target braking mode.

[0120] The processing device can also be implemented as a standalone or integrated module within the vehicle control unit (ECU), containing interface circuitry for receiving switch status and pressure value data, a microprocessor for executing diagnostic logic, and memory for storing diagnostic strategies and thresholds. For example, the processing device could be a dedicated diagnostic control unit responsible for receiving target braking mode information output by the acquisition device and receiving signals from the brake switch and brake fluid master cylinder pressure sensors in real time. This device performs comprehensive analysis of these input data by executing a preset diagnostic algorithm to determine whether the brake switch is in an abnormal state. As a preferred embodiment, the function of the processing device can also be implemented by software programs in the vehicle's brake control module (BCM) or vehicle dynamics control system (VDC), performing logical judgments and calculations on the received data to ultimately output diagnostic results. In practical applications, the functions of the acquisition device and the processing device can be integrated into the same physical control unit, working collaboratively through different software modules or tasks to achieve the entire monitoring and diagnostic process.

[0121] The vehicle brake switch status anomaly monitoring and diagnostic system proposed in this application represents a significant advancement over existing technologies. Traditional systems, when diagnosing brake switch anomalies, primarily rely on a simple, fixed physical correlation between the brake switch signal and the brake system pressure signal. This diagnostic logic is highly prone to misdiagnosis in modern vehicles, especially those with hybrid energy recovery and hydraulic braking control. For example, in pure kinetic energy recovery braking mode, if the brake switch is closed but the brake fluid master cylinder pressure is zero, a traditional system will incorrectly report a brake switch malfunction.

[0122] This application's system, by introducing an acquisition device and a processing device and clearly defining their respective functions, achieves comprehensive analysis of the brake switch status, the actual pressure value of the brake fluid master cylinder, and the target braking mode. The acquisition device is responsible for intelligently acquiring the target braking mode, breaking away from the reliance of traditional diagnostics on a single physical correlation. The processing device makes judgments based on this multi-dimensional information, capable of distinguishing between normal operating conditions (such as pure kinetic energy recovery braking or "with braking") and actual faults. Therefore, this application's system can more accurately identify abnormal states of the brake switch, effectively avoiding the high false alarm rate of traditional systems in complex braking scenarios, significantly improving the accuracy and reliability of diagnosis, and providing a more reliable guarantee for the safe operation of the vehicle.

[0123] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for monitoring and diagnosing abnormal states of vehicle brake switches, characterized in that, Includes the following steps: If the vehicle's brake switch is detected to be closed at the current moment, the target braking mode of the vehicle's braking system at the current moment is obtained from multiple braking modes; the target braking model includes pure kinetic energy recovery braking mode, mechanical braking mode or hybrid braking mode; After the braking system executes the target braking mode, the on / off state of the brake switch and the actual pressure value of the brake fluid master cylinder of the braking system are detected; the on / off state includes a closed state and an open state; The vehicle's brake switch is determined to be in an abnormal state based on the switch status, the actual pressure value, and the target braking mode. Determining whether the vehicle's brake switch is in an abnormal state based on the switch status, the actual pressure value, and the target braking mode includes: Determine whether the switch is in a closed state; When the switch is in the closed state, a first correspondence is obtained; the first correspondence includes a one-to-one correspondence between multiple braking modes and multiple abnormal state evaluation strategies. The abnormal state assessment strategy corresponding to the target braking mode in the first correspondence is taken as the target abnormal state assessment strategy. Based on the target abnormal state assessment strategy and the actual pressure value, it is determined whether the vehicle's brake switch is in an abnormal state.

2. The method for monitoring and diagnosing abnormal vehicle brake switch status according to claim 1, characterized in that, When the target braking mode is a pure kinetic energy recovery braking mode, determining whether the vehicle's brake switch is in an abnormal state based on the target abnormal state assessment strategy and the actual pressure value includes: Determine whether the actual pressure value is 0; If the actual pressure value is 0, it is determined that the vehicle's brake switch is in a normal state; If the actual pressure value is not 0, it is determined that the vehicle's brake switch is in an abnormal state.

3. The method for monitoring and diagnosing abnormal vehicle brake switch status according to claim 1, characterized in that, When the target braking mode is a mechanical braking mode or a hybrid braking mode, determining whether the vehicle's brake switch is in an abnormal state based on the target abnormal state assessment strategy and the actual pressure value includes: Obtain the expected pressure value of the brake fluid master cylinder in the braking system under the target braking mode; The vehicle's brake switch is determined to be in an abnormal state based on the expected pressure value and the actual pressure value.

4. The method for monitoring and diagnosing abnormal vehicle brake switch status according to claim 3, characterized in that, Determining whether the vehicle's brake switch is in an abnormal state based on the expected pressure value and the actual pressure value includes: The absolute value of the difference between the expected pressure value and the actual pressure value is taken as the target difference value; When the target difference is less than a preset difference threshold, the vehicle's brake switch is determined to be in a normal state. When the target difference is greater than or equal to a preset difference threshold, the vehicle's brake switch is determined to be in an abnormal state.

5. The method for monitoring and diagnosing abnormal vehicle brake switch status according to claim 1, characterized in that, After determining whether the switch is in a closed state, when the switch is in an open state, the method further includes: Obtain the first opening degree of the brake switch; When the first opening degree is greater than the preset opening degree threshold, the expected pressure value of the brake fluid master cylinder in the target braking mode is obtained; When the expected pressure value is 0 or the actual pressure value is 0, the brake switch is determined to be in an abnormal state.

6. The method for monitoring and diagnosing abnormal vehicle brake switch status according to claim 3, characterized in that, Obtain the target braking mode of the vehicle's braking system at the current moment from multiple braking modes, including: The vehicle speed, the state of charge of the vehicle's power battery, the inclination of the road where the vehicle is located, and the second opening degree of the brake switch are obtained at the current moment. The vehicle speed, the state of charge, the tilt, and the second opening degree are input into a preset braking mode determination model to obtain the target braking information at the current moment; the target braking information includes the target braking mode.

7. The method for monitoring and diagnosing abnormal vehicle brake switch status according to claim 6, characterized in that, The target braking information also includes the target braking force, and the expected pressure value of the brake fluid master cylinder in the braking system under the target braking mode is obtained, including: The initial pressure value of the brake fluid master cylinder is determined based on the target braking force; The minimum identification pressure value of the pressure detection device for detecting the pressure value of the brake fluid master cylinder is obtained; The expected pressure value is determined based on the minimum identification pressure value and the initial pressure value.

8. The method for monitoring and diagnosing abnormal vehicle brake switch status according to claim 7, characterized in that, Determining the expected pressure value based on the minimum identification pressure value and the initial pressure value includes: Determine whether the minimum identification pressure value is greater than the initial pressure value; If the minimum identification pressure value is greater than the initial pressure value, the expected pressure value is determined to be 0; If the minimum identification pressure value is less than or equal to the initial pressure value, the expected pressure value is determined to be the initial pressure value.

9. A vehicle brake switch status abnormality monitoring and diagnosis system, characterized in that, include: Acquisition device and processing device; The acquisition device is used to detect that the vehicle's brake switch is in a closed state at the current moment, and acquire the target braking mode of the vehicle's braking system at the current moment among multiple braking modes; the target braking mode includes pure kinetic energy recovery braking mode, mechanical braking mode or hybrid braking mode; The processing device is used to detect the on / off state of the brake switch and the actual pressure value of the brake fluid master cylinder of the braking system after the braking system executes the target braking mode; the on / off state includes a closed state and an open state; The processing device is also used to determine whether the vehicle's brake switch is in an abnormal state based on the switch state, the actual pressure value, and the target braking mode. The processing device is further configured to determine whether the vehicle's brake switch is in an abnormal state based on the switch state, the actual pressure value, and the target braking mode, including: Determine whether the switch is in a closed state; When the switch is in the closed state, a first correspondence is obtained; the first correspondence includes a one-to-one correspondence between multiple braking modes and multiple abnormal state evaluation strategies. The abnormal state assessment strategy corresponding to the target braking mode in the first correspondence is taken as the target abnormal state assessment strategy. Based on the target abnormal state assessment strategy and the actual pressure value, it is determined whether the vehicle's brake switch is in an abnormal state.

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