Pressure control method and device of one-way pressure building type one-box brake system in liquid supplement state, and determination and output method of liquid supplement completion flag

Abstract

The application discloses a pressure control method and device in a liquid supplement state of a one-way pressure building type OneBox brake system and a liquid supplement completion flag determination method, and belongs to the technical field of vehicle hydraulic brake-by-wire systems. The method comprises the following steps: liquid supplement working condition determination, target pressure limiting during liquid supplement, determination of liquid supplement completion when the servo cylinder pressure rises to above the pressure before liquid supplement and is stable, and output of a liquid supplement completion signal after the electromagnetic valve is switched. The device comprises four function modules corresponding to each step. The liquid supplement completion flag determination method switches the electromagnetic valve and then outputs the completion signal when the pressure rises and is stable. Through limiting control and timing optimization of the liquid supplement completion flag, the application suppresses the wheel cylinder pressure overshoot and the servo cylinder pressure fluctuation, improves brake smoothness, reduces system cost and does not need to add hardware, and is suitable for vehicles equipped with one-way pressure building type OneBox brake-by-wire systems.

Description

Technical Field

[0001] This invention belongs to the field of vehicle braking control technology, specifically relating to a pressure control method, device, and method for determining and outputting a fluid replenishment completion indicator in a one-way pressure-building OneBox braking system under fluid replenishment conditions. Background Technology

[0002] OneBox is a fully decoupled, highly integrated intelligent hydraulic brake-by-wire system that integrates ESC (Electronic Stability Control) with the brake master cylinder and pedal simulator into a single module. It has advantages such as small size, light weight, and fast response. It can build up 100 bar of pipeline pressure within 150 ms and has been widely used in pure electric, hybrid, and fuel-powered passenger vehicles.

[0003] In the OneBox product with unidirectional pressure-building capability, a servo motor drives a piston to build pressure in the wheel cylinder. Due to the limited capacity of the servo cylinder chamber, in conditions requiring a large supply of brake fluid (such as ABS on low-friction surfaces, or Antilock Brake System braking), the pressure-building piston must retract to a certain position before advancing to build pressure again; this process is called the fluid replenishment condition. During fluid replenishment, the pressure inside the servo cylinder chamber drops to near 0 bar, making it unable to continue providing pressure boosting to the wheel cylinder.

[0004] There is existing research on pressure control for OneBox products with unidirectional pressure building under liquid replenishment conditions.

[0005] In existing technology, a method for replenishing fluid in a braking control system involves adding a high-pressure accumulator and a solenoid valve to the braking control system. When the servo motor needs to retract for fluid replenishment, the high-pressure accumulator replenishes fluid and builds pressure by controlling the on / off state of the solenoid valve. However, this method relies on additional hardware, increasing the system structure and cost; furthermore, the high-pressure accumulator generates significant hydraulic shock when replenishing fluid after it has been replenished, affecting vehicle safety and the NVH performance of the fluid replenishment process.

[0006] Another technical solution proposes a comfort-optimized fluid replenishment control method. This method determines the replenishment request by acquiring the brake fluid consumption of the servo cylinders and switches the replenishment request to a comfort-oriented one based on vehicle speed or deceleration. It reduces replenishment noise by controlling the fluid flow rate and replenishment time. This solution focuses on NVH performance optimization during the replenishment process but does not address optimization of wheel cylinder pressure control during or after replenishment.

[0007] Furthermore, regarding the solenoid valve control strategy after fluid replenishment, existing solutions typically instruct multiple solenoid valves to sequentially open according to a preset time difference based on the servo cylinder's pressure information after fluid replenishment, thereby driving the motor to advance and build up pressure. These solutions focus on optimizing the solenoid valve opening sequence to reduce hydraulic shock, but do not address optimizing the control strategy for the ABS target pressure during fluid replenishment.

[0008] In the aforementioned existing technologies, the commonly used ABS control strategy is to control the system according to normal ABS logic, regardless of whether it is in a fluid replenishment condition. That is, in a fluid replenishment condition, if the condition of a single wheel is stable, the target pressure of that wheel continues to increase until the condition of that wheel becomes unstable, at which point the pressure is reduced or maintained.

[0009] However, the existing control strategies described above have the following technical drawbacks: First, because the actual pressure increase of a single wheel cylinder in a unidirectional pressure-building OneBox product is very limited or even nonexistent during fluid replenishment, the continuous increase in target pressure does not lead to a corresponding increase in actual pressure. This results in a large pressure difference between the target pressure and the estimated or actual pressure of the wheel cylinder when fluid replenishment is complete, causing overshoot of the actual pressure in the wheel cylinder. This causes the wheel to quickly enter an unstable state and depressurize, affecting braking smoothness. Second, after fluid replenishment, the rapid increase in fluid demand in one or more wheels causes significant fluctuations in the servo cylinder pressure. To avoid or mitigate these pressure fluctuations, existing solutions place higher demands on the dynamic response performance and control accuracy of the servo motor, leading to increased system costs. Third, existing solutions often rely on adding hardware such as high-voltage accumulators to improve fluid replenishment performance, increasing the mechanical complexity and BOM cost of the system. Summary of the Invention

[0010] The purpose of this invention is to provide a pressure control method for a one-way pressure-building OneBox braking system during fluid replenishment. By limiting the target ABS pressure of the wheel cylinder during fluid replenishment, and switching the state of the solenoid valve before fluid replenishment is completed and outputting a fluid replenishment completion signal after the servo cylinder pressure stabilizes, this invention aims to solve the technical problems of wheel cylinder pressure overshoot and servo cylinder pressure fluctuation after fluid replenishment, improve braking smoothness, and reduce system costs.

[0011] The second objective of this invention is to provide a pressure control device for a one-way pressure-building OneBox braking system in the fluid replenishment state. This device executes the aforementioned pressure control method by setting up a fluid replenishment condition determination module, a target pressure limiting module, a fluid replenishment completion determination module, and a control mode switching module.

[0012] The third objective of this invention is to provide a method for determining and outputting a fluid replenishment completion signal for a one-way pressure-building OneBox braking system. By switching the fluid replenishment-related solenoid valve to normal control state when the servo cylinder pressure rises above the pre-replenishment pressure and meets the stability conditions, and then outputting a fluid replenishment completion signal, the method aims to optimize the determination logic and output timing of the fluid replenishment completion signal, and avoid servo cylinder pressure fluctuations caused by premature issuance of the fluid replenishment completion signal.

[0013] To achieve the above objectives, the technical solution adopted by this invention is as follows: A pressure control method for a one-way pressure-building OneBox braking system under fluid replenishment conditions includes the following steps: S1. Liquid replenishment condition determination When the system determines that the servo motor piston is performing retraction and replenishment, it enters the replenishment mode; S2. Target pressure limit during fluid replenishment During the continuous fluid replenishment operation, the increase in the target ABS pressure of each wheel is limited to no more than a preset threshold. S3. Determination of completion of fluid rehydration Monitor the servo cylinder pressure. When the servo cylinder pressure rises back to above the pressure before replenishment and meets the preset stability conditions, the replenishment is considered complete. S4. Control Mode Switching After the fluid replenishment is completed, first switch the relevant solenoid valves to the normal control state, then output a fluid replenishment completion signal to restore normal ABS pressure control.

[0014] Furthermore, the preset threshold is 5 bar.

[0015] Furthermore, the preset stability conditions include: within a preset time window, the pressure fluctuation value of the servo cylinder does not exceed a preset fluctuation limit.

[0016] Furthermore, the preset duration window is 10ms, and the preset fluctuation limit is that the servo cylinder pressure is not lower than the pressure before replenishment.

[0017] Furthermore, the fluid replenishment condition is the ABS braking condition on a road surface with a low coefficient of adhesion.

[0018] Furthermore, during the fluid replenishment process, the target pressure of each wheel remains unchanged.

[0019] A pressure control device for a one-way pressure-building OneBox braking system under fluid replenishment conditions, used to implement the aforementioned pressure control method for the one-way pressure-building OneBox braking system under fluid replenishment conditions, the device comprising: The liquid replenishment condition determination module is used to determine whether the system has entered the liquid replenishment condition when the servo motor piston performs retraction liquid replenishment. The target pressure limiting module is used to limit the increase of the ABS target pressure of each wheel to no more than a preset threshold during the continuous fluid replenishment operation. The liquid replenishment completion determination module is used to monitor the servo cylinder pressure. When the servo cylinder pressure rises back to above the pressure before liquid replenishment and meets the preset stability conditions, the liquid replenishment is determined to be complete. The control mode switching module is used to switch the plunger isolation valve to the normal open control state after the fluid replenishment is completed, and then output a fluid replenishment completion signal to restore normal ABS pressure control; wherein, the plunger isolation valve is closed during fluid replenishment, and the motor performs retraction fluid replenishment.

[0020] A method for determining and outputting the completion indicator of fluid replenishment in a one-way pressure-building OneBox braking system, comprising: monitoring the actual pressure of the servo cylinder; When the pressure in the servo cylinder rises above the pressure before replenishment and meets the preset stability conditions, the relevant solenoid valves for replenishment are first switched to normal control mode, and then a replenishment completion signal is output.

[0021] The present invention, by adopting the above-described technical solution, achieves the following technical advancements compared to existing technologies: (1) This invention limits the increase of the target ABS pressure of each wheel to no more than a preset threshold (preferably 5 bar, more preferably keeping the current value unchanged) during the continuous replenishment process, thus avoiding the continuous accumulation of target pressure during replenishment. Since the actual pressure of the wheel cylinder cannot rise with the target pressure during replenishment, no significant pressure difference is generated between the target pressure and the actual pressure when replenishment is completed. This eliminates the wheel cylinder pressure overshoot caused by excessive pressure difference at the moment of replenishment completion, avoids the wheel from quickly entering an unstable state due to pressure overshoot, makes the braking deceleration change more gradual, and improves the braking comfort of the driver and passengers.

[0022] (2) This invention does not immediately output a replenishment completion signal to the control system after replenishment is completed. Instead, it first monitors whether the servo cylinder pressure has recovered to the level before replenishment and meets the stability condition. After the pressure stabilizes, the relevant solenoid valves for replenishment are switched to normal control state, and then the replenishment completion signal is output. This timing control avoids multiple wheels simultaneously generating a step increase in fluid demand at the moment of replenishment completion, making the servo cylinder pressure transition smoother and reducing hydraulic shock. Since the amplitude of servo cylinder pressure fluctuation is reduced, the system's requirements for the dynamic response bandwidth and control accuracy of the servo motor are correspondingly reduced. Under the same braking performance conditions, a lower specification motor and drive components can be selected, effectively reducing BOM costs.

[0023] (3) This invention achieves stable pressure control during fluid replenishment entirely through the built-in control algorithm of the electronic control unit, without the need for additional high-pressure accumulators, extra solenoid valves, or other hydraulic components, and without changing the hardware topology of the existing OneBox product. Compared with existing solutions that rely on adding hardware to improve fluid replenishment performance, this invention simplifies the system structure, reduces mechanical complexity and hardware costs while achieving the same or better braking performance. Furthermore, it has low engineering implementation risk and is easy to upgrade and deploy on existing product platforms.

[0024] (4) The limiting control strategy during fluid replenishment and the determination output strategy of fluid replenishment completion mark of the present invention can be implemented in concert to obtain the optimal control effect, or can be deployed independently according to the system configuration and control requirements of specific vehicle models. The limiting control strategy can be embedded into the existing control software as an independent functional module for ABS target pressure management during fluid replenishment, and the determination output strategy of fluid replenishment completion mark can be optimized as an independent functional module to optimize the fluid replenishment completion determination logic, which is convenient for flexible adaptation and calibration on different vehicle platform.

[0025] (5) In the prior art, the determination of the completion of fluid replenishment mostly relies on the position of the servo motor or the timer, and lacks direct consideration of the actual pressure state of the servo cylinder. The present invention uses the actual pressure of the servo cylinder rising back to above the pressure before fluid replenishment and meeting the preset stability conditions as the basis for determining the completion of fluid replenishment. The determination logic has clear physical meaning and quantifiable calibration parameters (such as duration window and fluctuation limit), which makes it convenient for engineering calibration personnel to make targeted adjustments according to the characteristics of different vehicle models and braking systems, and improves the adaptability and robustness of the control algorithm.

[0026] In summary, this invention effectively solves the technical problems of wheel cylinder pressure overshoot and servo cylinder pressure fluctuation under the fluid replenishment condition of the OneBox product with unidirectional pressure building, by optimizing the ABS target pressure limiting control during fluid replenishment and the timing of fluid replenishment completion determination, without the need for additional hardware. It significantly improves braking smoothness, reduces system cost, and has high engineering practical value and industrial application prospects. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0028] In the attached diagram: Figure 1 This is a hydraulic schematic diagram of the unidirectional pressure-building OneBox braking product in Embodiment 1 of the present invention; Figure 2 A flowchart of the pressure control method for the unidirectional pressure-building OneBox braking system under fluid replenishment state provided in Embodiment 1 of the present invention; Figure 3 The graph shows the test results of the target pressure of the wheel cylinder and the pressure of the servo cylinder after adopting the control strategy of Embodiment 1 of the present invention; Figure 4 This is a flowchart of the method for determining and outputting the fluid replenishment completion mark of the OneBox braking system with unidirectional pressure build-up provided in Embodiment 3 of the present invention. Detailed Implementation

[0029] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0030] Example 1 This embodiment provides a pressure control method for a unidirectional pressure-building OneBox braking system under fluid replenishment conditions.

[0031] like Figure 1 As shown, the OneBox unidirectional pressure-building braking product integrates ESC, the brake master cylinder, and the pedal simulator into a single module. This product includes a servo motor, servo cylinders, pressure sensors located at the servo cylinders, and hydraulic lines connected to the four wheel cylinders. Each wheel cylinder's hydraulic line is equipped with a pressure-boosting valve and a pressure-reducing valve for independent pressure control. The electronic control unit (ECU) is electrically connected to the servo motor, pressure sensors, each pressure-boosting valve, and each pressure-reducing valve to receive sensor signals and output control commands. Figure 1 The correspondence between the letters and the components of the hydraulic system is shown in the table below.

[0032] Table 1 During conventional ABS control, the ECU calculates the slip ratio of each wheel based on the wheel speed signals collected by the wheel speed sensors, and determines the target pressure for each wheel cylinder accordingly. The ECU controls the servo motor to drive the piston movement in the servo cylinder, and coordinates with the on / off states of the booster and depressurizer valves to achieve independent adjustment of the actual pressure of each wheel cylinder.

[0033] like Figure 2 As shown, the pressure control method provided in Embodiment 1 of the present invention includes the following steps: When a vehicle is traveling on a low-friction surface and applying ABS braking, due to the limited capacity of the servo cylinder, the brake fluid volume in the servo cylinder may become insufficient to meet the fluid requirements of the wheel cylinders during continuous braking. At this point, step S1 is initiated, where the ECU controls the servo motor to retract the piston to a predetermined position to replenish brake fluid from the reservoir. This process is known as the fluid replenishment operation. During fluid replenishment, the pressure in the servo cylinder drops to near 0 bar, making it unable to continue providing pressurization to the wheel cylinders.

[0034] During fluid replenishment, the ECU first executes the fluid replenishment condition determination step S1. Specifically, the ECU monitors the servo motor's rotation angle signal, the servo cylinder's pressure signal, and the wheel cylinder's estimated pressure signal in real time. When it detects that the servo motor-driven piston needs to perform a retraction action, the ECU determines that it has entered the fluid replenishment condition and sets the fluid replenishment status flag.

[0035] Then, in step S2, the ECU executes the target pressure limiting step during fluid replenishment. While the fluid replenishment status flag is active, the ECU pauses the regular incremental calculation of the ABS target pressure for each wheel. Specifically, the ECU locks the current ABS target pressure for each wheel at its current value and stops increasing it according to the regular ABS algorithm. Since the actual wheel cylinder pressure cannot rise with the target pressure command during fluid replenishment, keeping the target pressure constant avoids a large pressure difference between the target pressure and the actual wheel cylinder pressure at the end of fluid replenishment, thus eliminating wheel cylinder pressure overshoot caused by excessive pressure difference at the moment of fluid replenishment completion.

[0036] In step S2, the preset threshold for the limiting control can be set to 5 bar, meaning that the increase in the target ABS pressure of each wheel during fluid replenishment does not exceed 5 bar. In a preferred embodiment, the target pressure remains unchanged. This 5-bar limiting threshold is determined by bench calibration based on the system pressure and fluid volume between the brake master cylinder and the wheel cylinder booster valves. Those skilled in the art can adaptively adjust this threshold through calibration for different vehicle platforms or system configurations.

[0037] Then, in step S3, the ECU performs the fluid replenishment completion determination step. The ECU continuously receives the actual pressure value of the servo cylinder from the pressure sensor located at the servo cylinder. When the servo cylinder pressure is detected to rise above the pre-replenishment pressure, the ECU starts a stabilization determination timer. During the fluid replenishment process, the wheel cylinder pressure is generally slightly lower than the pre-replenishment pressure. Therefore, it is necessary to ensure that the servo cylinder pressure rises above the pre-replenishment pressure and meets the stabilization condition before determining that fluid replenishment is complete. If fluid replenishment is determined to be complete prematurely and the fluid replenishment state is exited, the wheel cylinder pressure will suddenly drop. If the pressure fluctuation value of the servo cylinder does not exceed the preset fluctuation limit within the preset time window, the ECU determines that the servo cylinder has stabilized and fluid replenishment is complete. If the servo cylinder pressure does not rise above the pre-replenishment pressure, or if the pressure fluctuation exceeds the preset limit after rising, the ECU continues to wait and monitor.

[0038] In step S3 above, in this embodiment, if the pressure of the servo cylinder exceeds the pressure before replenishment and remains so for 10ms, the pressure is considered stable and replenishment is complete.

[0039] Then, proceeding to step S4, after fluid replenishment is complete, the ECU executes the control mode switching step. First, the ECU switches the plunger isolation valve to the normal open control state. The plunger isolation valve is closed during fluid replenishment, and the motor performs retraction fluid replenishment; after replenishment is complete, it switches back to the normal open control state. After the solenoid valve state switching is complete, the ECU clears the fluid replenishment status flag and outputs a fluid replenishment complete signal. Afterward, normal ABS pressure control resumes for each wheel, and the target pressure for each wheel cylinder is recalculated incrementally based on wheel slip ratio and other state variables. The servo motor and corresponding solenoid valves cooperate to execute pressurization, pressure holding, or pressure reduction commands.

[0040] Figure 3 The test results of the target wheel cylinder pressure and servo cylinder pressure after adopting the control strategy of this embodiment are shown. As can be seen from the figure, during the retraction process of the servo cylinder motor push rod, i.e., during fluid replenishment, the target wheel cylinder pressure of all four wheels remains constant and does not show a continuous increase. After fluid replenishment is completed, i.e., the servo cylinder pressure is greater than or equal to the pressure before fluid replenishment, and normal ABS control is then performed. The pressure of the four wheel cylinders gradually increases until the wheels become unstable. At this point, the servo cylinder pressure fluctuation is small, the change in vehicle braking deceleration is small, and the braking smoothness is good.

[0041] Example 2 This embodiment provides a pressure control device for a one-way pressure-building OneBox braking system under fluid replenishment conditions.

[0042] The pressure control device is integrated into the electronic control unit (ECU), which includes a fluid replenishment condition determination module, a target pressure limiting module, a fluid replenishment completion determination module, and a control mode switching module.

[0043] The fluid replenishment condition determination module is used to determine when the system enters the fluid replenishment condition if the servo motor piston is performing a retraction fluid replenishment. Specifically, this module receives the rotation angle signal of the servo motor and the pressure signal from the pressure sensor located at the servo cylinder in real time. When it is detected that the servo motor drives the piston to perform a retraction action and the pressure in the servo cylinder continues to drop to near 0 bar, this module sets the fluid replenishment status flag.

[0044] The target pressure limiting module is used to limit the increment of the ABS target pressure of each wheel to no more than a preset threshold during the continuous fluid replenishment operation. While the fluid replenishment status flag is active, this module suspends the regular increment calculation of the ABS target pressure of each wheel, locking the current ABS target pressure of each wheel at its current value and preventing it from continuously increasing according to the conventional ABS algorithm. This preset threshold can be set to 5 bar; in a preferred embodiment, the target pressure remains unchanged at its current value.

[0045] The fluid replenishment completion determination module monitors the servo cylinder pressure. Fluid replenishment is determined to be complete when the servo cylinder pressure rises above the pre-replenishment pressure and meets preset stability conditions. During fluid replenishment, the wheel cylinder pressure is generally slightly lower than the pre-replenishment pressure; therefore, it is necessary to ensure the servo cylinder pressure rises above the pre-replenishment pressure before determining fluid replenishment completion. Prematurely determining fluid replenishment completion and exiting the replenishment state will cause a sudden drop in wheel cylinder pressure. This module continuously receives the actual servo cylinder pressure value from the pressure sensor. When the servo cylinder pressure is detected to rise above the pre-replenishment pressure, the module starts a stability determination timer. If the pressure fluctuation value of the servo cylinder does not exceed the preset fluctuation limit within the preset time window, the module determines that the servo cylinder has stabilized and fluid replenishment is complete.

[0046] The control mode switching module is used to switch the relevant solenoid valves to normal control mode after fluid replenishment is completed, and then output a fluid replenishment completion signal to restore normal ABS pressure control. After the fluid replenishment completion determination module outputs its determination result, this module first sends a switching command to the relevant solenoid valves to switch them to the state required for normal ABS control. Once the solenoid valve state switching is complete, the module clears the fluid replenishment status flag and outputs a fluid replenishment completion signal, restoring normal ABS pressure control to each wheel.

[0047] The functions of each module mentioned above correspond one-to-one with the control logic of each step in Embodiment 1. For specific implementation methods, please refer to the relevant description in Embodiment 1, which will not be repeated here.

[0048] Example 3 This embodiment provides a method for determining and outputting the fluid replenishment completion indicator for a one-way pressure-building OneBox braking system.

[0049] like Figure 1 As shown, in the OneBox brake product with unidirectional pressure build-up, the electronic control unit (ECU) receives the actual pressure value of the servo cylinder from the pressure sensor located at the servo cylinder in real time.

[0050] like Figure 4As shown, the method for determining and outputting the liquid replenishment completion indicator provided in this embodiment includes the following steps: When the system is in liquid replenishment mode, the servo motor drives the piston in the servo cylinder to retract, and the pressure in the servo cylinder drops to close to 0 bar. After liquid replenishment is completed, the servo motor drives the piston forward, and the pressure in the servo cylinder gradually rises. Entering step S101, the ECU monitors the actual pressure of the servo cylinder in real time and determines whether the servo cylinder pressure has risen above the pressure before liquid replenishment. If the pressure has risen above the pressure before liquid replenishment, proceed to step S102; if the pressure has not risen above the pressure before liquid replenishment, continue monitoring and waiting. Entering step S102, the ECU initiates stability determination and continuously monitors the pressure fluctuation value of the servo cylinder within a preset time window. If the pressure fluctuation value within this time window does not exceed the preset fluctuation limit, it is determined that the servo cylinder has met the stability condition, and proceed to step S103; if the pressure fluctuation value exceeds the preset limit, return to step S101 to continue monitoring. In step S103, after the stabilization conditions are met, the ECU first sends a switching command to the plunger isolation valve, switching it from the closed state during fluid replenishment to the normal open control state. The plunger isolation valve is closed during fluid replenishment, and the motor performs retraction fluid replenishment; after fluid replenishment is complete, it switches to the normal open control state. In step S104, after the solenoid valve state switch is complete, the ECU outputs a fluid replenishment completion signal. This signal notifies the ABS control module that fluid replenishment is complete and normal ABS pressure control can be restored.

[0051] The aforementioned timing control logic of "switching the solenoid valve first and then outputting the fluid replenishment completion signal" ensures that when the ABS control module receives the fluid replenishment completion signal, the hydraulic circuit is already in a normally controllable state, thereby avoiding servo cylinder pressure fluctuations caused by the synchronization or lag between the solenoid valve state switching and the fluid replenishment completion signal output.

[0052] The preset duration window is preferably 10ms, and the preset fluctuation limit is preferably that the servo cylinder pressure is not lower than the pressure before fluid replenishment. The above fluid replenishment condition is preferably an ABS braking condition on a road surface with a low coefficient of adhesion.

[0053] The method for determining and outputting the fluid replenishment completion indicator described in this embodiment can be implemented as an independent functional module, or it can be implemented in conjunction with the pressure control method described in Embodiment 1. The specific deployment method can be flexibly selected according to the control system architecture of the vehicle platform.

Claims

1. A pressure control method for a one-way pressure-building OneBox braking system under fluid replenishment conditions, characterized in that, Includes the following steps: S1. Liquid replenishment condition determination When the system determines that the servo motor piston is performing retraction and replenishment, it enters the replenishment mode; S2. Target pressure limit during fluid replenishment During the continuous fluid replenishment operation, the increase in the target ABS pressure of each wheel is limited to no more than a preset threshold. S3. Determination of completion of fluid rehydration Monitor the servo cylinder pressure. When the servo cylinder pressure rises back to above the pressure before replenishment and meets the preset stability conditions, the replenishment is considered complete. S4. Control Mode Switching After the fluid replenishment is completed, first switch the relevant solenoid valves to the normal control state, then output a fluid replenishment completion signal to restore normal ABS pressure control.

2. The pressure control method for the unidirectional pressure-building OneBox braking system under fluid replenishment state according to claim 1, characterized in that, The preset threshold is 5 bar.

3. The pressure control method for the unidirectional pressure-building OneBox braking system under fluid replenishment state according to claim 1 or 2, characterized in that, The preset stability conditions include: within a preset time window, the pressure fluctuation value of the servo cylinder does not exceed a preset fluctuation limit.

4. The pressure control method for the unidirectional pressure-building OneBox braking system under fluid replenishment state according to claim 3, characterized in that, The preset duration window is 10ms, and the preset fluctuation limit is that the servo cylinder pressure is not lower than the pressure before replenishment.

5. The pressure control method for the unidirectional pressure-building OneBox braking system under fluid replenishment state according to claim 1, 2, or 4, characterized in that, The fluid replenishment condition refers to the ABS braking condition on roads with low adhesion coefficients.

6. The pressure control method for the unidirectional pressure-building OneBox braking system under fluid replenishment state according to claim 1, 2, or 4, characterized in that, During the fluid replenishment process, the target pressure of each wheel remains unchanged.

7. A pressure control device for a one-way pressure-building OneBox braking system in a fluid-filling state, used to implement the pressure control method for the one-way pressure-building OneBox braking system in a fluid-filling state as described in any one of claims 1 to 6, characterized in that, The device includes: The liquid replenishment condition determination module is used to determine whether the system has entered the liquid replenishment condition when the servo motor piston performs retraction liquid replenishment. The target pressure limiting module is used to limit the increase of the ABS target pressure of each wheel to no more than a preset threshold during the continuous fluid replenishment operation. The liquid replenishment completion determination module is used to monitor the servo cylinder pressure. When the servo cylinder pressure rises back to above the pressure before liquid replenishment and meets the preset stability conditions, the liquid replenishment is determined to be complete. The control mode switching module is used to switch the plunger isolation valve to the normal open control state after the fluid replenishment is completed, and then output a fluid replenishment completion signal to restore normal ABS pressure control; wherein, the plunger isolation valve is closed during fluid replenishment, and the motor performs retraction fluid replenishment.

8. A method for determining and outputting the completion indicator of fluid replenishment in a one-way pressure-building OneBox braking system, characterized in that, include: Monitor the actual pressure of the servo cylinder; When the pressure in the servo cylinder rises above the pressure before replenishment and meets the preset stability conditions, the relevant solenoid valves for replenishment are first switched to normal control mode, and then a replenishment completion signal is output.

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