A control diagnosis method for an electric vehicle driving brake assist system

Abstract

The application discloses a control diagnosis method of an electric vehicle driving brake assisting system, which comprises the following steps: firstly, judging and processing input signals; secondly, controlling an electric vacuum pump by a vehicle controller and diagnosing faults of the electric vacuum pump; thirdly, controlling a relay and diagnosing faults of the relay; and finally, detecting and diagnosing faults of a vacuum pressure sensor. Through collecting data such as atmospheric pressure, system vacuum pressure and brake switches, an electric vacuum pump control strategy meeting the electric vehicle driving brake assisting requirement is formulated, the driving control requirement of the electric vehicle is better met, and a more effective driving fault warning strategy is formed.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle control systems, and more specifically to an electric vehicle driving brake assist system and its control strategy and fault diagnosis method. Background Technology

[0002] Currently, the principle of brake vacuum booster in gasoline-powered vehicles is to utilize the pressure difference between the negative pressure generated by the engine during operation and atmospheric pressure to produce a braking assist effect, thereby reducing the force applied to the brake pedal. Electric vehicles, however, use electric vacuum pumps, which brings some problems, including:

[0003] ①The system stops working when the vacuum level meets the system requirements and starts working when the vacuum level is insufficient;

[0004] ②Due to the current industry-wide lifespan issues of relays;

[0005] ③ Electric vacuum pumps can achieve different levels of vacuum at different altitudes;

[0006] ④ No fault alarm in the service brake assist system;

[0007] Therefore, in practical terms, it is necessary to provide a new vehicle braking assist system to solve the above problems. Summary of the Invention

[0008] This invention discloses a control and diagnostic method for an electric vehicle's service braking assist system, the main purpose of which is to overcome the aforementioned deficiencies and shortcomings of the existing technology.

[0009] The technical solution adopted in this invention is as follows:

[0010] A control diagnostic method for an electric vehicle's service braking assist system, characterized by the following specific steps:

[0011] Step 1: Judgment and processing of input signals: Input signals include: brake pedal switch signal, atmospheric pressure sensor signal and vacuum pressure sensor signal. The vehicle controller performs pre-judgment and processing of the above input signals.

[0012] Step 2: Control of the electric vacuum pump: The vehicle controller controls the electric vacuum pump and performs fault diagnosis of the electric vacuum pump.

[0013] Step 3: Relay Control: The vehicle controller controls the relays and performs relay fault diagnosis, including the following specific methods:

[0014] A. Perform adhesion detection: When the relay is in the open state, the assist system detects whether the voltage at the relay sampling point is high. If it is high, it reports a relay adhesion fault.

[0015] B. When the key is turned to the ON position for the first time, the power steering system only closes the backup relay and checks whether the voltage at the relay sampling point is high. If it is not high, it reports "backup relay fault"; if it is high, it closes the main relay after a 1-second timer. After the main relay closes, it counts for 0.5 seconds, then disconnects the backup relay and checks whether the voltage at the relay sampling point is high. If it is not high, it reports "main relay fault".

[0016] C. When the electric vacuum pump reaches the start-up condition, instead of the "key being turned ON for the first time", the assist system closes the service relay and checks whether the voltage at the relay sampling point is high. If a closing command is not detected for 0.5 seconds, the status of the service and standby relays is swapped, and "service relay failure" is reported.

[0017] D. Two-way relay failure: When the system control command is to close the vacuum pump relay, but the relay is not detected to be closed, a two-way vacuum pump relay failure is issued and the failure is reported. At the same time, the vehicle speed is limited and power is restored only after the failure is cleared.

[0018] E. Commonly used relay life warning: When the vehicle controller detects that the number of times a single relay has been used has reached the maintenance set value, it will issue a commonly used relay life warning. After maintenance, the relay will be reset using software.

[0019] F. Backup relay life warning: When the vehicle controller detects that the number of times a single relay has been used has reached the maintenance set value, it will issue a backup relay life warning. After maintenance, the relay will be reset using software.

[0020] Step 4: Detection and fault diagnosis of vacuum pressure sensor: The vehicle controller controls the vacuum pressure sensor and performs fault diagnosis of the vacuum pressure sensor.

[0021] Furthermore, in step 1, the vehicle controller performs pre-judgment and processing of various input signals, including: judging the altitude of the vehicle based on the signal input from the atmospheric pressure sensor, and judging and setting various working thresholds.

[0022] Furthermore, the control of the electric vacuum pump by the vehicle controller in step 2 includes the following specific methods:

[0023] A. Determine the effective working conditions: If the vehicle is in a charging state, the vacuum system is ineffective; if the key is turned to the ON position, the vacuum system is effective regardless of the vehicle's state; if the key is turned to the OFF position and the power steering system is in a power-off delay state, the vacuum system is effective.

[0024] B. When the key is turned to the ON position for the first time, if the current vacuum level is detected to be greater than the pump stop threshold, the electric vacuum pump will be turned on until the pump stop threshold is reached and then turned off.

[0025] C. When the vehicle is driving normally, if the current vacuum level is detected to be greater than the set pump start threshold, the electric vacuum pump will be turned on until the pump stop threshold is reached and then turned off.

[0026] Furthermore, the fault diagnosis of the electric vacuum pump by the vehicle controller in step 2 includes the following specific methods:

[0027] A. Initial low vacuum warning: If the vacuum level is lower than the set low vacuum threshold after the first power-on, an initial low vacuum warning will be issued and the fault will be reported and processed. The system will automatically recover after the fault is cleared.

[0028] B. High Vacuum Warning: After power-on, if the vacuum level is detected to be higher than the set alarm threshold, a high vacuum warning will be issued and the fault will be reported and processed. The system will automatically recover after the fault is cleared.

[0029] C. Minor air circuit leak fault: When there is no braking signal and it lasts for 6 seconds, if the vacuum pressure value of the air circuit rises to the set minor leak threshold, a minor air circuit leak fault will be issued and the fault handling will be reported. At the same time, the maximum vehicle speed will be limited. The system will automatically recover after the fault is cleared.

[0030] D. Moderate air circuit leakage fault: When there is no braking signal and it lasts for 6 seconds, the vacuum pressure value of the air circuit rises to the set moderate leakage threshold, or when there is no braking signal and the electric vacuum pump continues to work for 6 seconds, the vacuum pressure value of the air circuit drops to less than 0, then a moderate air circuit leakage fault is issued and the fault handling is reported. At the same time, the maximum vehicle speed is limited. The system will automatically recover after the fault is cleared.

[0031] E. Air circuit height leakage fault: When there is no braking signal and it lasts for 6 seconds, if the vacuum pressure value of the air circuit rises to the set height leakage threshold, an air circuit height leakage fault will be issued and the fault handling will be reported. At the same time, the maximum vehicle speed will be limited. After the fault is cleared, the power will be restored.

[0032] F. Single working time exceeds the limit: When the working time of the electric vacuum pump exceeds the set maximum working time T, a single working time exceeds the limit fault will be issued and the fault handling will be reported. At the same time, the maximum vehicle speed will be limited and the electric vacuum pump will be forcibly stopped for 7 seconds. After the fault is cleared, the power will be restored.

[0033] Furthermore, in step 4, the vehicle controller controls the vacuum pressure sensor and performs fault diagnosis, including the following specific methods:

[0034] A. Vacuum pressure sensor failure: When no vacuum pressure sensor signal is detected, a vacuum pressure sensor failure fault is issued and reported. At the same time, the electric vacuum pump is controlled to cycle on a "work for 7 seconds and stop for 7 seconds" basis, and the maximum vehicle speed is limited. The system will automatically resume operation after the fault is cleared.

[0035] B. Vacuum pressure sensor malfunction: When the pressure value of the vacuum pressure sensor is detected to be less than the minimum threshold or greater than the maximum threshold, a vacuum pressure sensor malfunction fault is issued and reported. At the same time, the electric vacuum pump is controlled to cycle on a "work for 7 seconds and stop for 7 seconds" basis, and the maximum vehicle speed is limited. The system will automatically resume operation after the fault is cleared.

[0036] As can be seen from the above description of the present invention, compared with the prior art, the advantages of the present invention are:

[0037] 1. This invention, by collecting data such as atmospheric pressure, system vacuum pressure, and brake switch, formulates an electric vacuum pump control strategy that meets the vehicle's driving brake assist requirements, better satisfies the driving control requirements of electric vehicles, and forms a more effective driving fault alarm strategy.

[0038] 2. This invention, through the scheme of setting up a dual relay circuit and the relay alarm strategy, can meet the usage mileage of 300,000 kilometers over 3 years for vehicles, and solves the technical problem of low average lifespan of relays in the industry.

[0039] 3. By adding an atmospheric pressure sensor and a vacuum system pressure sensor, and combining them with the control strategy of an electric vacuum pump, this invention can solve the problem of driving in different altitude areas, thereby enabling the wider promotion and application of electric vehicles.

[0040] 4. This invention develops a more effective system fault alarm strategy through circuit signal detection, thus solving the shortcomings of existing vehicle control systems.

[0041] 5. This invention integrates the controller into the vehicle controller, replacing the separate electric vacuum pump controller, resulting in a more reasonable structure and optimized control effect. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the framework principle structure of the present invention. Detailed Implementation

[0043] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0044] like Figure 1As shown, an electric vehicle braking assist system includes a brake pedal switch, a vacuum pressure sensor, a vehicle controller, an atmospheric pressure sensor, an electric vacuum pump, a relay group, and a battery pack. The vehicle controller is connected to the brake pedal switch, atmospheric pressure sensor, vacuum pressure sensor, and electric vacuum pump. The battery pack is electrically connected to the electric vacuum pump through the relay group. The relay group includes two parallel-connected main relays and a spare relay, and the two relays are connected to the vehicle controller. The electric vacuum pump is connected to a vacuum storage tank, and the vacuum pressure sensor is used to monitor the pressure of the vacuum storage tank in real time.

[0045] Furthermore, a fuse resistor is also provided between the battery pack and the relay pack.

[0046] Furthermore, the battery pack is a 12V battery.

[0047] A control diagnostic method for an electric vehicle's service brake assist system includes the following specific steps:

[0048] Step 1: Judgment and processing of input signals: Input signals include: brake pedal switch signal, atmospheric pressure sensor signal and vacuum pressure sensor signal. The vehicle controller performs pre-judgment and processing of the above input signals.

[0049] Step 2: Control of the electric vacuum pump: The vehicle controller controls the electric vacuum pump and performs fault diagnosis of the electric vacuum pump.

[0050] Step 3: Control of relays: The vehicle controller controls the relays and performs relay fault diagnosis;

[0051] Step 4: Detection and fault diagnosis of vacuum pressure sensor: The vehicle controller controls the vacuum pressure sensor and performs fault diagnosis of the vacuum pressure sensor.

[0052] Furthermore, in step 1, the vehicle controller performs pre-judgment and processing of various input signals, including: judging the altitude of the vehicle based on the signal input from the atmospheric pressure sensor, and judging and setting various working thresholds.

[0053] Furthermore, the control of the electric vacuum pump by the vehicle controller in step 2 includes the following specific methods:

[0054] A. Determine the effective working conditions: If the vehicle is in a charging state, the vacuum system is ineffective; if the key is turned to the ON position, the vacuum system is effective regardless of the vehicle's state; if the key is turned to the OFF position and the power steering system is in a power-off delay state, the vacuum system is effective.

[0055] B. When the key is turned to the ON position for the first time, if the current vacuum level is detected to be greater than the pump stop threshold, the electric vacuum pump will be turned on until the pump stop threshold is reached and then turned off.

[0056] C. When the vehicle is driving normally, if the current vacuum level is detected to be greater than the set pump start threshold, the electric vacuum pump will be turned on until the pump stop threshold is reached and then turned off.

[0057] Furthermore, the fault diagnosis of the electric vacuum pump by the vehicle controller in step 2 includes the following specific methods:

[0058] A. Initial low vacuum warning: If the vacuum level is lower than the set low vacuum threshold after the first power-on, an initial low vacuum warning will be issued and the fault will be reported and processed. The system will automatically recover after the fault is cleared.

[0059] B. High Vacuum Warning: After power-on, if the vacuum level is detected to be higher than the set alarm threshold, a high vacuum warning will be issued and the fault will be reported and processed. The system will automatically recover after the fault is cleared.

[0060] C. Minor air circuit leak fault: When there is no braking signal and it lasts for 6 seconds, if the vacuum pressure value of the air circuit rises to the set minor leak threshold, a minor air circuit leak fault will be issued and the fault handling will be reported. At the same time, the maximum vehicle speed will be limited. The system will automatically recover after the fault is cleared.

[0061] D. Moderate air circuit leakage fault: When there is no braking signal and it lasts for 6 seconds, the vacuum pressure value of the air circuit rises to the set moderate leakage threshold, or when there is no braking signal and the electric vacuum pump continues to work for 6 seconds, the vacuum pressure value of the air circuit drops to less than 0, then a moderate air circuit leakage fault is issued and the fault handling is reported. At the same time, the maximum vehicle speed is limited. The system will automatically recover after the fault is cleared.

[0062] E. Air circuit height leakage fault: When there is no braking signal and it lasts for 6 seconds, if the vacuum pressure value of the air circuit rises to the set height leakage threshold, an air circuit height leakage fault will be issued and the fault handling will be reported. At the same time, the maximum vehicle speed will be limited. After the fault is cleared, the power will be restored.

[0063] F. Single working time exceeds the limit: When the working time of the electric vacuum pump exceeds the set maximum working time T, and the electric vacuum pump has not been shut down, a single working time exceeds the limit fault is issued and the fault handling is reported. At the same time, the maximum vehicle speed is limited and the electric vacuum pump is forcibly stopped for 7 seconds. The power is restored after the fault is cleared.

[0064] The table below shows the operating thresholds of electric vacuum pumps at different altitudes:

[0065] Furthermore, in step 3, the vehicle controller controls the relays and performs fault diagnosis, including the following specific methods:

[0066] A. Perform adhesion detection: When the relay is in the open state, the assist system detects whether the voltage at the relay sampling point is high. If it is high, it reports a relay adhesion fault.

[0067] B. When the key is turned to the ON position for the first time, the power steering system only closes the backup relay and checks whether the voltage at the relay sampling point is high. If it is not high, it reports "backup relay fault"; if it is high, it closes the main relay after a 1-second timer. After the main relay closes, it counts for 0.5 seconds, then disconnects the backup relay and checks whether the voltage at the relay sampling point is high. If it is not high, it reports "main relay fault".

[0068] C. When the electric vacuum pump reaches the start-up condition, instead of the "key being turned ON for the first time", the assist system closes the service relay and checks whether the voltage at the relay sampling point is high. If a closing command is not detected for 0.5 seconds, the status of the service and standby relays is swapped, and "service relay failure" is reported.

[0069] D. Two-way relay failure: When the system control command is to close the vacuum pump relay, but the relay is not detected to be closed, a two-way vacuum pump relay failure is issued and the failure is reported. At the same time, the vehicle speed is limited and power is restored only after the failure is cleared.

[0070] E. Commonly used relay life warning: When the vehicle controller detects that the number of times a single relay has been used has reached the maintenance set value, it issues a commonly used relay life warning. After maintenance, it is reset using specific software.

[0071] F. Backup relay life warning: When the vehicle controller detects that the number of times a single relay has been used has reached the maintenance set value, it will issue a backup relay life warning. After maintenance, the relay will be reset using specific software.

[0072] Furthermore, in step 4, the vehicle controller controls the vacuum pressure sensor and performs fault diagnosis, including the following specific methods:

[0073] A. Vacuum pressure sensor failure: When no vacuum pressure sensor signal is detected, a vacuum pressure sensor failure fault is issued and reported. At the same time, the electric vacuum pump is controlled to cycle on a "work for 7 seconds and stop for 7 seconds" basis, and the maximum vehicle speed is limited. The system will automatically resume operation after the fault is cleared.

[0074] B. Vacuum pressure sensor malfunction: When the pressure value of the vacuum pressure sensor is detected to be less than the minimum threshold or greater than the maximum threshold, a vacuum pressure sensor malfunction fault is issued and reported. At the same time, the electric vacuum pump is controlled to cycle on and off for 7 seconds and the maximum vehicle speed is limited. The system will automatically resume operation after the fault is cleared.

[0075] Furthermore, when the voltage is too high, vacuum pressure sensor failure takes precedence over vacuum pressure sensor malfunction.

[0076] 1. This invention, by collecting data such as atmospheric pressure, system vacuum pressure, and brake switch, formulates an electric vacuum pump control strategy that meets the vehicle's driving brake assist requirements, better satisfies the driving control requirements of electric vehicles, and forms a more effective driving fault alarm strategy.

[0077] 2. This invention, through the scheme of setting up a dual relay circuit and the relay alarm strategy, can meet the usage mileage of 300,000 kilometers over 3 years for vehicles, and solves the technical problem of low average lifespan of relays in the industry.

[0078] 3. By adding an atmospheric pressure sensor and a vacuum system pressure sensor, and combining them with the control strategy of an electric vacuum pump, this invention can solve the problem of driving in different altitude areas, thereby enabling the wider promotion and application of electric vehicles.

[0079] 4. This invention develops a more effective system fault alarm strategy through circuit signal detection, thus solving the shortcomings of existing vehicle control systems.

[0080] 5. This invention integrates the controller into the vehicle controller, replacing the separate electric vacuum pump controller, resulting in a more reasonable structure and optimized control effect.

[0081] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial improvements made to the present invention using this concept should be considered as infringing on the protection scope of the present invention.

Claims

1. A control diagnostic method for an electric vehicle's service brake assist system, characterized in that: The specific steps include the following: Step 1: Judgment and processing of input signals: Input signals include: brake pedal switch signal, atmospheric pressure sensor signal and vacuum pressure sensor signal. The vehicle controller performs pre-judgment and processing of the above input signals. Step 2: Control of the electric vacuum pump: The vehicle controller controls the electric vacuum pump and performs fault diagnosis of the electric vacuum pump. Step 3: Relay Control: The vehicle controller controls the relays and performs relay fault diagnosis, including the following specific methods: A. Perform adhesion detection: When the relay is in the open state, the assist system detects whether the voltage at the relay sampling point is high. If it is high, it reports a relay adhesion fault. B. When the key is turned to the ON position for the first time, the power assist system only closes the backup relay and checks whether the voltage at the relay sampling point is high. If it is not high, it reports "backup relay fault"; if it is high, it closes the main relay after a 1-second timer. After the main relay closes, it times for 0.5 seconds, then disconnects the backup relay and checks whether the voltage at the relay sampling point is high. If it is not high, it reports "main relay fault". C. When the electric vacuum pump reaches the start-up condition, the assist system closes the service relay, and checks whether the voltage at the relay sampling point is high. If a closing command is not detected for 0.5 seconds, the status of the service relay and the standby relay are swapped, and "service relay failure" is reported. D. Two-way relay failure: When the system control command is to close the vacuum pump relay, but the relay is not detected to be closed, a two-way vacuum pump relay failure is issued and the failure is reported. At the same time, the vehicle speed is limited and power is restored only after the failure is cleared. E. Commonly used relay life warning: When the vehicle controller detects that the number of times a single relay has been used has reached the maintenance set value, it will issue a commonly used relay life warning. After maintenance, the relay will be reset using software. F. Backup relay life warning: When the vehicle controller detects that the number of times a single relay has been used has reached the maintenance set value, it will issue a backup relay life warning. After maintenance, the relay will be reset using software. Step 4: Detection and fault diagnosis of vacuum pressure sensor: The vehicle controller controls the vacuum pressure sensor and performs fault diagnosis of the vacuum pressure sensor.

2. The control and diagnostic method for an electric vehicle service braking assist system according to claim 1, characterized in that: In step 1, the vehicle controller performs pre-judgment and processing of various input signals, including: judging the altitude of the vehicle based on the signal input from the atmospheric pressure sensor, and judging and setting various working thresholds.

3. The control and diagnostic method for an electric vehicle service brake assist system according to claim 1, characterized in that: The control of the electric vacuum pump by the vehicle controller in step 2 includes the following specific methods: A. Determine the effective working conditions: If the vehicle is in a charging state, the vacuum system is ineffective; if the key is turned to the ON position, the vacuum system is effective regardless of the vehicle's state; if the key is turned to the OFF position and the power steering system is in a power-off delay state, the vacuum system is effective. B. When the key is turned to the ON position for the first time, if the current vacuum level is detected to be greater than the pump stop threshold, the electric vacuum pump will be turned on until the pump stop threshold is reached and then turned off. C. When the vehicle is driving normally, if the current vacuum level is detected to be greater than the set pump start threshold, the electric vacuum pump will be turned on until the pump stop threshold is reached and then turned off.

4. The control and diagnostic method for an electric vehicle service braking assist system according to claim 1, characterized in that: In step 2, the vehicle controller's fault diagnosis of the electric vacuum pump includes the following specific methods: A. Initial low vacuum warning: If the vacuum level is lower than the set low vacuum threshold after the first power-on, an initial low vacuum warning will be issued and the fault will be reported and processed. The system will automatically recover after the fault is cleared. B. High Vacuum Warning: After power-on, if the vacuum level is detected to be higher than the set alarm threshold, a high vacuum warning will be issued and the fault will be reported and processed. The system will automatically recover after the fault is cleared. C. Minor air circuit leak fault: When there is no braking signal and it lasts for 6 seconds, if the vacuum pressure value of the air circuit rises to the set minor leak threshold, a minor air circuit leak fault will be issued and the fault handling will be reported. At the same time, the maximum vehicle speed will be limited. The system will automatically recover after the fault is cleared. D. Moderate air circuit leakage fault: When there is no braking signal and it lasts for 6 seconds, the vacuum pressure value of the air circuit rises to the set moderate leakage threshold, or when there is no braking signal and the electric vacuum pump continues to work for 6 seconds, the vacuum pressure value of the air circuit drops to less than 0, then a moderate air circuit leakage fault is issued and the fault handling is reported. At the same time, the maximum vehicle speed is limited. The system will automatically recover after the fault is cleared. E. Air circuit height leakage fault: When there is no braking signal and it lasts for 6 seconds, if the vacuum pressure value of the air circuit rises to the set height leakage threshold, an air circuit height leakage fault will be issued and the fault handling will be reported. At the same time, the maximum vehicle speed will be limited. After the fault is cleared, the power will be restored. F. Single working time exceeds the limit: When the working time of the electric vacuum pump exceeds the set maximum working time T, a single working time exceeds the limit fault will be issued and the fault handling will be reported. At the same time, the maximum vehicle speed will be limited and the electric vacuum pump will be forcibly stopped for 7 seconds. After the fault is cleared, the power will be restored.

5. The control and diagnostic method for an electric vehicle service brake assist system according to claim 1, characterized in that: In step 4, the vehicle controller controls the vacuum pressure sensor and performs fault diagnosis, including the following specific methods: A. Vacuum pressure sensor failure: When no vacuum pressure sensor signal is detected, a vacuum pressure sensor failure fault is issued and reported. At the same time, the electric vacuum pump is controlled to cycle on "work for 7 seconds and stop for 7 seconds" and the maximum vehicle speed is limited. The system will automatically resume operation after the fault is cleared. B. Vacuum pressure sensor malfunction: When the pressure value of the vacuum pressure sensor is detected to be less than the minimum threshold or greater than the maximum threshold, a vacuum pressure sensor malfunction fault is issued and reported. At the same time, the electric vacuum pump is controlled to cycle on a "work for 7 seconds and stop for 7 seconds" basis, and the maximum vehicle speed is limited. The system will automatically resume operation after the fault is cleared.

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