Treatment system and method for failure of new energy vehicle electronic hydraulic brake system

Abstract

The present application relates to the field of new energy vehicle control, in particular to a new energy vehicle electronic hydraulic brake system failure processing system and method, real-time monitoring of the state signal and fault message of the electronic hydraulic brake system EHB; hierarchical response according to the monitored fault type; when it is determined that the electronic hydraulic brake system EHB has the highest level fault of losing basic braking capability, the first degradation strategy is triggered, when it is detected that the electronic hydraulic brake system EHB communication is completely lost but the highest level fault is not reported in advance, the second degradation strategy is triggered, solving the problem of how to ensure that the vehicle can still maintain the basic braking capability and safely limp when the electronic hydraulic brake system EHB of the new energy vehicle at the present stage has a serious fault leading to the failure of its hydraulic backup function, so as to avoid the complete paralysis of the vehicle and secondary safety accidents.

Description

Technical Field

[0001] This invention relates to the field of braking control for new energy vehicles, and specifically to a system and method for handling failures of the electro-hydraulic braking system in new energy vehicles. Background Technology

[0002] The braking systems of new energy vehicles typically integrate energy recovery functions to improve energy efficiency. Currently, the mainstream technical routes include: traditional mechanical braking systems (such as vacuum boosters or air brakes), which are low in cost but not linked to energy recovery; electromechanical braking systems (EMB) that eliminate hydraulic lines and rely entirely on electrical signals to transmit braking intentions, but lack mechanical redundancy and have higher safety risks, so they are mostly used for parking brakes; and electro-hydraulic braking systems (EHB) that combine electric braking and hydraulic backup and are widely used.

[0003] Although the EHB system has a hydraulic-mechanical backup function, this backup function will also fail when a specific concurrent failure occurs in its key mechanical components (such as pressure sensors, accumulators, and key valve bodies). At this time, the system cannot distribute sufficient mechanical braking force to the front axle according to the ideal braking force curve, resulting in the electric braking capacity not being fully utilized, the overall vehicle braking performance deteriorating, and posing a safety hazard.

[0004] In summary, this invention proposes a system and method for handling the failure of the electronic hydraulic braking system in new energy vehicles to solve the problems mentioned in the background art. Summary of the Invention

[0005] The purpose of this invention is to provide a degradation treatment method after the failure of the electronic hydraulic braking system (EHB) of a new energy vehicle. This method solves the problem of how to ensure that the vehicle can still maintain basic braking capability and limp safely when a serious fault occurs in the EHB of a new energy vehicle, which causes the hydraulic backup function to fail, so as to avoid complete vehicle paralysis and secondary safety accidents.

[0006] The handling method for the failure of the electro-hydraulic braking system in new energy vehicles is executed by the vehicle control unit, and the specific steps are as follows:

[0007] Step S1: Monitor the status signals and fault messages of the electro-hydraulic braking system (EHB) in real time;

[0008] Step S2: Implement a tiered response based on the detected fault type;

[0009] Step S3: When it is determined that the electro-hydraulic braking system (EHB) has experienced the highest level of failure resulting in loss of basic braking capability, the first degradation strategy is triggered. The first degradation strategy includes: implementing vehicle speed limits and drive power limits that match the load according to the overall vehicle load status; ignoring the regular electric braking requests issued by the electro-hydraulic braking system (EHB), and instead querying the preset three-dimensional energy recovery MAP based on the vehicle speed, brake pedal opening and overall vehicle weight to calculate and execute the optimal electric braking torque.

[0010] Step S4: When a complete loss of EHB communication in the electro-hydraulic braking system is detected without prior reporting of the highest-level fault, a second degradation strategy is triggered. The second degradation strategy includes:

[0011] VCU disengages from electric braking control, and the EHB (electro-hydraulic braking system) automatically responds to the brake pedal to perform basic hydraulic braking.

[0012] Implement a set of relatively lenient load-adaptive speed limits that differ from those for the highest level of fault.

[0013] Turn on the system fault indicator light.

[0014] To further define, the highest level of fault refers to the combination of faults that causes the EHB hydraulic backup function to fail, corresponding to the vehicle's three-level fault level.

[0015] Further specifying, the speed limit matching the load capacity is:

[0016] Under the first degradation strategy, the speed limit is 50 km / h when unloaded, 40 km / h when half-loaded, and 30 km / h when fully loaded.

[0017] Under the second degradation strategy, the speed limit is 60 km / h when unloaded, 50 km / h when half-loaded, and 40 km / h when fully loaded.

[0018] Further specifying, under the first degradation strategy, the drive power is uniformly limited to 20% of the peak power.

[0019] Furthermore, the calibration principle of the three-dimensional energy recovery MAP is: under the premise that the torque is provided only by the electric braking of the rear wheels, the deceleration of the whole vehicle under different loads, vehicle speeds and pedal openings should be as linear as possible and in line with the driver's expectations.

[0020] Furthermore, the second degradation strategy is a strategy implemented after communication loss.

[0021] Further, it also includes a fault recovery confirmation step. After the fault is eliminated, the first or second degradation strategy will continue to be executed. Only when the driver performs a vehicle power-on restart operation will the VCU exit the degradation mode and return to the normal brake energy recovery control mode.

[0022] The system for handling failures of the electronic hydraulic braking system in new energy vehicles includes a fault monitoring and classification module, which is used to receive and parse the fault information reported by EHB and identify the highest level fault or communication loss state that has lost basic braking capability.

[0023] The load status recognition module is used to estimate or obtain the vehicle weight in real time and divide the vehicle into empty, half-loaded, and fully loaded ranges.

[0024] The adaptive speed and power limiting module is used to call the corresponding vehicle speed and drive power limit values ​​according to different fault levels and load conditions.

[0025] The electric braking strategy switching module is used to switch from receiving EHB requests to automatic torque calculation based on three-dimensional MAP in the event of the highest level fault, and to exit electric braking control in the event of communication loss.

[0026] The fault indication and recovery management module is used to control the fault light signal and manage the entry and exit logic of the degradation strategy.

[0027] Furthermore, the fault indication and recovery management module is configured to only exit the current degradation strategy mode during the next high-voltage power-on restart of the vehicle after the fault is cleared.

[0028] The advantages of this invention compared to the prior art are:

[0029] 1. A new level of safety redundancy has been established. In the extreme case where both the EHB hydraulic backup and conventional electric braking fail, a third level of safety redundancy is created through vehicle-level collaborative control to ensure that the vehicle does not lose its most basic movement and braking capabilities.

[0030] 2. It has achieved refined risk management and innovatively introduced the vehicle load as a core variable into the fault degradation strategy. Different speed limits and power restrictions are implemented for braking requirements and inertial risks under different loads, achieving the optimal balance between safety and traffic efficiency.

[0031] 3. Braking strategy separation mechanism: It distinguishes between two fundamentally different fault modes, namely "mechanical function failure" and "communication function failure", and provides targeted strategies for "VCU taking over electric braking" and "VCU exiting and EHB handling itself" respectively. The control logic is more precise and avoids false intervention or missed protection.

[0032] 4. Through the preset three-dimensional energy recovery MAP, it can still provide a relatively smooth and expected braking feel in the event of a serious system failure. The key restart confirmation mechanism avoids sudden changes in braking force, which significantly reduces driving panic and secondary safety risks caused by failure. At the same time, it avoids complete vehicle paralysis and reduces the economic and time costs for users. Attached Figure Description

[0033] Figure 1 This is a system diagram of the overall control of the fault handling system of the present invention;

[0034] Figure 2 This is the highest-level fault handling flowchart for the EHB of this invention;

[0035] Figure 3 This is a flowchart of the communication loss handling process for the EHB of this invention. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] Example:

[0038] like Figures 1-3 As shown, the highest level of fault handling is as follows: The VCU continuously receives the EHB status message through the CAN bus. When the message contains a predefined "Level 3 fault" code (such as a combination of dual-path fault of the booster chamber pressure sensor, accumulator failure, etc.), the VCU determines that the EHB has lost its basic braking capability.

[0039] At this time, the VCU immediately sets the internal fault flag EHB_3lvlfltflg. After the vehicle fault handling module detects this flag, it performs the following actions:

[0040] Send a command to the gateway to illuminate the red warning light for the braking system on the dashboard, alerting the driver to a serious malfunction.

[0041] Call the load status recognition result: If the vehicle weight estimated by the air suspension pressure sensor is greater than the full load threshold M_full, it is determined to be fully loaded and the speed limit is 30km / h. If it is between the full load threshold M_full and the empty load threshold M_empty, it is determined to be half load and the speed limit is 40km / h. If it is less than the empty load threshold M_empty, it is determined to be empty and the speed limit is 50km / h. At the same time, send a command to the motor controller to clamp the upper limit of drive power to 20% of the peak power.

[0042] Upon switching to the electric braking strategy, the VCU no longer responds to the BrakeTorqueReq signal in the EHB bus message. When the driver depresses the brake pedal, the VCU receives the pedal opening signal, combines it with the current vehicle speed and overall vehicle weight, queries the three-dimensional energy recovery MAP, and directly sends the target braking torque command to the motor controller. This MAP has been calibrated on the test bench and in the actual vehicle to ensure the stability of the rear wheel electric braking when it operates alone. The VCU directly sends the target braking torque command to the motor controller based on the query result.

[0043] Communication loss fault handling: If the VCU detects a timeout interruption in CAN communication with the EHB, and the last valid message before the interruption does not contain a level 3 fault code, then a communication loss fault is identified. The following actions are then performed:

[0044] The VCU immediately stops sending any electric braking torque commands, and the vehicle braking relies entirely on the response of the EHB's internal hydraulic system to the pedal signal. Due to the loss of communication, the EHB can still work independently to complete basic braking.

[0045] Implement the speed limit strategy under communication loss mode: 40km / h when fully loaded, 50km / h when half-loaded, and 60km / h when unloaded, and illuminate the yellow general system fault light on the instrument panel. The hydraulic braking function is normal in this mode, so a relatively high vehicle speed is allowed.

[0046] There are no additional limitations on drive power to ensure basic driving capabilities.

[0047] During any of the above fault handling processes, even if the VCU subsequently detects that the fault source has disappeared (e.g., communication is restored and no fault codes are found), although the fault flags inside the VCU are cleared, the actively applied speed limiter, power limiter, and special electric braking MAP will remain active. Only when the driver turns the vehicle key or ignition switch to the OFF position and then back to the ON position to complete a full vehicle high-voltage power-on restart will the VCU reinitialize all control parameters and return to the normal regenerative braking control mode. This ensures that the braking torque will not undergo unexpected sudden changes before the fault is completely eliminated.

[0048] The above provides a detailed description of the processing system and method for the failure of the electronic hydraulic braking system of new energy vehicles provided by the present invention. The description of the specific embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for handling the failure of an electro-hydraulic braking system in a new energy vehicle, characterized in that: This is executed by the vehicle control unit, and the specific steps are as follows: Step S1: Monitor the status signals and fault messages of the electro-hydraulic braking system (EHB) in real time; Step S2: Implement a tiered response based on the detected fault type; Step S3: When it is determined that the electro-hydraulic braking system (EHB) has experienced the highest level of failure resulting in loss of basic braking capability, the first degradation strategy is triggered. The first degradation strategy includes: implementing vehicle speed limits and drive power limits that match the load according to the overall vehicle load status; ignoring the regular electric braking requests issued by the electro-hydraulic braking system (EHB), and instead querying the preset three-dimensional energy recovery MAP based on the vehicle speed, brake pedal opening and overall vehicle weight to calculate and execute the optimal electric braking torque. Step S4: When a complete loss of EHB communication in the electro-hydraulic braking system is detected without prior reporting of the highest-level fault, a second degradation strategy is triggered. The second degradation strategy includes: VCU disengages from electric braking control, and the EHB (electro-hydraulic braking system) automatically responds to the brake pedal to perform basic hydraulic braking. Implement a set of relatively lenient load-adaptive speed limits that differ from those for the highest level of fault. Turn on the system fault indicator light.

2. The method for handling the failure of the electro-hydraulic braking system of a new energy vehicle according to claim 1, characterized in that: The highest level of fault refers to the combination of faults that causes the EHB hydraulic backup function to fail, corresponding to the vehicle's level three fault level.

3. The method for handling the failure of the electro-hydraulic braking system of a new energy vehicle according to claim 1, characterized in that: The speed limit matching the load capacity is as follows: Under the first degradation strategy, the speed limit is 50 km / h when unloaded, 40 km / h when half-loaded, and 30 km / h when fully loaded. Under the second degradation strategy, the speed limit is 60 km / h when unloaded, 50 km / h when half-loaded, and 40 km / h when fully loaded.

4. The method for handling the failure of the electronic hydraulic braking system of a new energy vehicle according to claim 1, characterized in that: Under the first degradation strategy, the drive power is uniformly limited to 20% of the peak power.

5. The method for handling the failure of the electronic hydraulic braking system of a new energy vehicle according to claim 1, characterized in that... The calibration principle of the three-dimensional energy recovery MAP is: under the premise that the torque is provided only by the electric braking of the rear wheels, the deceleration of the whole vehicle under different loads, speeds and pedal openings should be as linear as possible and in line with the driver's expectations.

6. The method for handling the failure of the electro-hydraulic braking system of a new energy vehicle according to claim 1, characterized in that: The second degradation strategy is the strategy after communication loss. Complete communication loss means that the CAN communication between VCU and EHB has not received any messages for more than a preset time threshold, and the missing messages do not contain a level 3 fault code.

7. The method for handling the failure of the electro-hydraulic braking system of a new energy vehicle according to claim 1, characterized in that: It also includes a fault recovery confirmation step. After the fault is eliminated, the first or second degradation strategy will continue to be executed. Only when the driver performs the vehicle power-on restart operation will the VCU exit the degradation mode and return to the normal brake energy recovery control mode.

8. A system for handling failures of an electro-hydraulic braking system in a new energy vehicle, applicable to the method for handling failures of an electro-hydraulic braking system in a new energy vehicle according to any one of claims 1-7, characterized in that: It includes a fault monitoring and classification module, which is used to receive and parse fault information reported by EHB, and identify the highest level fault or communication loss state that has lost basic braking capability. The load status recognition module is used to estimate or obtain the vehicle weight in real time and divide the vehicle into empty, half-loaded, and fully loaded ranges. The adaptive speed and power limiting module is used to call the corresponding vehicle speed and drive power limit values ​​according to different fault levels and load conditions. The electric braking strategy switching module is used to switch from receiving EHB requests to automatic torque calculation based on three-dimensional MAP in the event of the highest level fault, and to exit electric braking control in the event of communication loss. The fault indication and recovery management module is used to control the fault light signal and manage the entry and exit logic of the degradation strategy.

9. The system for handling failures of the electro-hydraulic braking system for new energy vehicles according to claim 8, characterized in that: The fault indication and recovery management module is configured to allow exiting the current degradation strategy mode only during the next high-voltage power-on restart of the vehicle after the fault is cleared.

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