A method for releasing residual brake fluid pressure and an electronic hydraulic brake system

Abstract

The present invention relates to the field of vehicle braking technology, and specifically to a residual brake fluid pressure relief method and an electronic hydraulic brake system. The residual brake fluid pressure relief method comprises setting a learning zero position in a pressure building chamber, wherein the distance between the learning zero position and the software zero position is set as a total pressure relief stroke; judging whether to perform a pressure relief action based on when a piston is at the learning zero position; obtaining a pressure relief stroke of the piston that meets the pressure relief requirement based on liquid pressure information; when performing the pressure relief action, the piston at the learning zero position moves a pressure relief stroke toward a motor; and an electronic hydraulic brake system adopts the above-mentioned residual brake fluid pressure relief method; in the present application, when there is residual fluid pressure in the pressure building chamber, the piston can relieve pressure by moving within the range of the total pressure relief stroke, thereby achieving "digestion" of the residual fluid pressure in the pressure building chamber, eliminating the influence of the residual fluid pressure on the brake system, and achieving the effect of relieving the residual fluid pressure consistent with the fluid replenishing hole.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle braking, and in particular to a residual brake fluid pressure relief method and an electronic hydraulic braking system. Background Art

[0002] During the operation of the brake system, since the brake fluid can be compensated through the oil pot, it is difficult to avoid excessive compensation, resulting in residual fluid pressure in the brake circuit when the pressure-building piston retreats to the initial position, causing the vehicle to drag, increase fuel consumption and reduce the life of the brake system. The conventional solution for relieving residual pressure is to design a fluid replenishment hole. When the piston retreats to the rear end of the fluid replenishment hole, the fluid replenishment hole can connect the brake system with the oil pot, thereby relieving the residual fluid pressure.

[0003] For example, a braking system for a vehicle described in Chinese invention patent CN107264504B, in which an electro-hydraulic brake booster is activated when a brake operating element is operated, so that the brake pressure in at least one wheel brake cylinder is increased; and at least one wheel brake cylinder is decoupled from the master brake cylinder by closing at least one separation valve. In its hydraulic principle diagram, a fluid filling hole is designed near the initial position of the pressure-building chamber piston, and a one-way valve is designed at the position where the pressure-building chamber piston is pushed to the bottom.

[0004] When the brakes are released quickly, the pressure-building piston is quickly withdrawn. When the return speed of the liquid in the brake line is not fast enough to fill the withdrawal speed of the pressure-building chamber, negative pressure will be generated in the pressure-building chamber, causing the brake fluid in the oil pot to flow into the pressure-building chamber through the one-way valve. In addition, when the pressure-building cylinder piston returns to overshoot, the brake fluid in the oil pot will also flow into the pressure-building chamber through the one-way valve. Therefore, when the pressure-building chamber piston is pulled back to the bottom, the brake fluid in the pipeline is more than the initial state, and there will be residual liquid pressure in the brake circuit.

[0005] However, when there is no fluid replenishment hole design in the braking system, it is more difficult to release the residual hydraulic pressure; and if the residual fluid pressure is only released by the fluid replenishment hole, the release efficiency is low. At the same time, the design process of the fluid replenishment hole is difficult, and the aperture of the fluid replenishment hole needs to be controlled. When the aperture of the fluid replenishment hole is small, the pressure relief efficiency is low. When the aperture of the fluid replenishment hole is large, the size of the sealing leather cup used will be larger, which will make the size of the entire device larger and increase the manufacturing cost.

[0006] In view of this, a residual brake fluid pressure relief method and an electronic hydraulic brake system are proposed. The residual pressure state can be monitored in real time through an adaptive motor piston zero position learning method. The residual pressure can be "digested" in the PSU cavity through a software strategy, which can better eliminate the influence of the residual fluid pressure on the brake system and achieve the effect of relieving the residual fluid pressure consistent with the fluid filling hole, while at a lower cost. Summary of the invention

[0007] In view of the above problems existing in the prior art, the present invention provides a method for relieving residual brake fluid pressure and an electronic hydraulic brake system.

[0008] In order to solve the above technical problems, the present invention is solved by the following technical solutions:

[0009] In a first aspect, a method for relieving residual brake fluid pressure is provided, which comprises:

[0010] A learning zero position is set in the pressure building chamber, the position of the piston represented by the learning zero position is farther away from the motor than the position of the piston represented by the software zero position, and the distance between the learning zero position and the software zero position is set as the total pressure relief stroke;

[0011] Determining whether to perform a pressure relief action based on the hydraulic pressure information of the pressure-building chamber when the actual position of the piston is at the learning zero position and the current state information of the vehicle;

[0012] Acquiring a pressure relief stroke of the piston that satisfies a pressure relief requirement based on the hydraulic pressure information;

[0013] When performing the pressure relief action, the piston at the learning zero position moves toward the direction of the motor by the pressure relief stroke, and the position of the piston after the movement is updated to the position of the piston represented by the learning zero position.

[0014] As a preferred embodiment, when setting a zero position in the pressure chamber, the method specifically includes:

[0015] Open the CSV separation valve and the PSV separation valve, and when the piston moves to the mechanical zero position, move the piston to the learning zero stroke in the direction away from the motor, and set the actual position of the piston at this time as the learning zero position.

[0016] Preferably, when judging whether to perform the pressure relief action based on the hydraulic pressure information of the pressure-building chamber when the actual position of the piston is at the learning zero position and the current vehicle status information, specifically includes:

[0017] Setting a pressure relief threshold of the pressure-building chamber;

[0018] Acquiring hydraulic pressure information of the pressure building chamber;

[0019] It is determined whether to activate a pressure relief request based on the pressure relief threshold and the hydraulic pressure information.

[0020] Preferably, when judging whether to perform the pressure relief action based on the hydraulic pressure information of the pressure-building chamber when the actual position of the piston is at the learning zero position and the current vehicle status information, specifically includes:

[0021] The current vehicle speed, braking information, throttle information and EPB status information are acquired as the status information of the current vehicle, and the braking demand of the current vehicle is determined based on the status information of the current vehicle.

[0022] Preferably, the step of obtaining the pressure relief stroke of the piston that satisfies the pressure relief requirement based on the hydraulic pressure information specifically includes:

[0023] The pressure relief stroke is calculated based on the hydraulic pressure information and the pressure relief threshold.

[0024] Preferably, when performing the pressure relief action, the piston at the learning zero position moves the pressure relief stroke toward the direction of the motor, and the position of the piston after the movement is updated to the position of the piston represented by the learning zero position, specifically including:

[0025] When the pressure relief stroke is greater than the total pressure relief stroke,

[0026] The CSV separation valve and the PSV separation valve are opened, the piston moves to the mechanical zero position, and then moves the learning zero stroke in the direction away from the motor, and the position of the piston after movement is updated to the position of the piston represented by the learning zero position.

[0027] Preferably, when the pressure relief stroke is greater than the zero stroke,

[0028] Pressure relief is performed by moving the piston to the mechanical zero position and the pressure relief circuit of the current vehicle; when the piston moves to the mechanical zero position, the learning zero stroke is moved in the direction away from the motor, and the position of the piston after movement is updated to the position of the piston represented by the learning zero position.

[0029] Preferably, when performing a pressure relief action, when it is determined based on the status information of the current vehicle that the current vehicle has a braking demand, the piston changes from performing a pressure relief action to performing a pressure building action.

[0030] Preferably, when the piston changes from performing a pressure relief action to performing a pressure building action, the method specifically includes:

[0031] The position of the piston when it is switched is updated to the position of the piston represented by the learning zero position.

[0032] In a second aspect, an electronic hydraulic brake system is provided, the brake system comprising an oil tank, a CSV separation valve, a PSV separation valve, a pressure building cylinder and a pressure relief circuit;

[0033] The CSV separation valve is connected to the oil pot, the pressure building cylinder and the pressure relief circuit respectively; the PSV separation valve is connected to the oil pot, the pressure building cylinder and the pressure relief circuit respectively, and the PSV separation valve is connected to the CSV separation valve; the braking system adopts the above-mentioned residual brake fluid pressure relief method.

[0034] The present invention has at least the following beneficial effects:

[0035] The present application sets a learning zero position on the basis of the mechanical zero position and the software zero position. The position of the piston represented by the learning zero position is farther away from the motor than the position of the piston represented by the mechanical zero position and the software zero position. That is to say, the position of the piston is further moved a certain distance away from the motor. The distance between the learning zero position and the software zero position is set as the total pressure relief stroke. When there is residual liquid pressure in the pressure building chamber, the piston can relieve pressure by moving within the range of the total pressure relief stroke, thereby achieving "digestion" of the residual liquid pressure in the pressure building chamber, and can solve the problem of releasing residual liquid pressure in the scheme without a fluid replenishment hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of a pressure-building cylinder, a piston and a motor in some embodiments of the present application is shown;

[0037] Figure 2 A schematic diagram showing the process of the piston moving to the mechanical zero position and then moving to the learning zero stroke when the vehicle is started in some embodiments of the present application;

[0038] Figure 3 A schematic diagram showing the process of decompression of the piston when the decompression stroke is less than the total decompression stroke in some embodiments of the present application;

[0039] Figure 4 A schematic diagram of the process of decompression of the piston when the decompression stroke is greater than the total decompression stroke and less than the zero stroke in some embodiments of the present application is shown;

[0040] Figure 5 A schematic diagram of the process of decompression of the piston when the decompression stroke is greater than the zero stroke in some embodiments of the present application is shown;

[0041] Figure 6 A schematic diagram of an electronic hydraulic brake system in some embodiments of the present application is shown;

[0042] Figure 7 A flow chart of a method for relieving residual brake fluid pressure in some embodiments of the present application is shown.

[0043] The parts indicated by the numbers in the accompanying drawings are as follows:

[0044] 10. Pressure building cylinder; 11. Pressure building chamber; 12. Piston; 100. Motor; 200. OV valve; 300. CSV separation valve; 400. PSV separation valve; 500. Oil pot. DETAILED DESCRIPTION

[0045] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments are only for explaining the present invention and are not intended to limit it.

[0046] like Figure 1 and Figure 6 As shown, the braking system of the vehicle includes a pressure-building cylinder 10 and a motor 100. A movable piston 12 is arranged in the pressure-building chamber 11 of the pressure-building cylinder 10. The motor 100 is arranged at one end of the pressure-building cylinder 10, and the output shaft of the motor 100 extends into the pressure-building chamber 11 and is fixedly connected to the piston 12. When the output shaft of the motor 100 extends, it can drive the piston 12 to move in the pressure-building chamber 11 in a direction away from the motor 100, push out the liquid in the pressure-building chamber 11, and thus realize the pressure-building process; when the output shaft of the motor 100 retracts, it can drive the piston 12 to move in the pressure-building chamber 11 in the direction of the motor 100, and thus realize the pressure-releasing process.

[0047] The pressure-building cylinder 10 of the brake system is usually divided into two structures: with a fluid-filling hole and without a fluid-filling hole. When the pressure-building cylinder 10 is a structure without a fluid-filling hole, the brake system only relieves pressure through the brake circuit. Relieving pressure through the brake circuit generally requires adding a pressure relief circuit or a solenoid valve, which will make the overall circuit complex, with a high failure rate, and a slow response when performing the pressure relief action. When the pressure-building cylinder 10 is a structure with a fluid-filling hole, the brake system can relieve pressure through the brake circuit and the fluid-filling hole. However, whether the pressure is relieved through the pressure relief circuit or through the cooperation of the brake circuit and the fluid-filling hole, the action is performed more frequently, which has a great impact on the service life of the solenoid valve. This solution not only achieves the same effect of relieving residual liquid pressure as the fluid-filling hole and has a lower cost, but also uses the pressure relief circuit to assist in pressure relief only when the residual liquid pressure is too large, which can extend the service life of the solenoid valve and ensure the braking experience of the vehicle.

[0048] First, as Figure 1 and Figure 7 As shown, Figure 1 A in the middle represents the zero position when the vehicle is started. Figure 1 B in the middle represents software zero position. Figure 1 The C in the middle represents the mechanical zero position. Figure 1 D in the middle represents the total pressure relief stroke when the vehicle is started. Figure 1 The E in the figure represents zero stroke. The present application proposes a method for relieving residual brake fluid pressure, comprising:

[0049] Step S100, a learning zero position is set in the pressure building chamber 11, the position of the piston 12 represented by the learning zero position is farther away from the motor 100 than the position of the piston 12 represented by the software zero position, and the distance between the learning zero position and the software zero position is set as the total pressure relief stroke.

[0050] The mechanical zero position represents a specific position of the piston 12 in the pressure-building chamber 11; in actual applications, the pressure-building chamber 11 is also set with a mechanical zero position and a software zero position, wherein the mechanical zero position represents the position where the piston 12 moves to the bottom in the pressure-building chamber 11 toward the direction of the motor 100, and the software zero position is the position of the piston 12 after moving a certain distance away from the motor 100 at the mechanical zero position; it is understandable that when the piston 12 moves to the mechanical zero position, it will collide with the pressure-building chamber 11, and the piston 12 is likely to rebound, which makes the vehicle's control system have errors when monitoring the position of the piston 12, and by setting the software zero position, the distance for the piston 12 to rebound can be reserved, so that the vehicle's control system can monitor the position of the piston 12 more accurately.

[0051] On the basis of the mechanical zero position and the software zero position, a learning zero position is set. The position of the piston 12 represented by the learning zero position is farther away from the motor 100 than the position of the piston 12 represented by the mechanical zero position and the software zero position. That is to say, the position of the piston 12 is further moved a certain distance away from the motor 100. The distance between the learning zero position and the software zero position is set as the total pressure relief stroke. When there is residual liquid pressure in the pressure building chamber 11, the piston 12 can relieve pressure by moving within the range of the total pressure relief stroke, thereby realizing "digestion" of the residual liquid pressure in the pressure building chamber 11, which can greatly reduce the opening and closing frequency of the solenoid valve.

[0052] Step S200: determining whether to perform a pressure relief action based on the hydraulic pressure information of the pressure chamber 11 when the actual position of the piston 12 is at the zero position and the current vehicle status information.

[0053] When the piston 12 in the pressure building chamber 11 is in the learning zero position, the piston 12 moves in the direction away from the motor 100 and completes the pressure building action, then the piston 12 will retreat, that is, move in the direction of the motor 100. When the piston 12 moves to the learning zero position, at this time, the position of the piston 12 corresponds to the position before the pressure building. The control system of the vehicle can determine whether the current vehicle has a pressure relief demand and whether to perform the pressure relief action through the piston 12 by obtaining the liquid pressure information of the pressure building chamber 11 at this time and the current vehicle status information.

[0054] Step S300: obtaining a pressure relief stroke of the piston 12 that meets the pressure relief requirement based on the hydraulic pressure information.

[0055] When the vehicle control system determines that the current vehicle has a pressure relief demand and performs a pressure relief action, the control system further calculates the pressure relief stroke that the piston 12 needs to move through the hydraulic pressure information of the pressure-building cylinder 10, and the pressure relief demand of the current vehicle can be met by moving the piston 12 to a corresponding pressure relief stroke. At this time, the pressure relief demand should not be greater than the total pressure relief stroke.

[0056] Step S400, when performing the pressure relief action, the piston 12 at the learning zero position moves toward the direction of the motor 100 by the pressure relief stroke, and the position of the piston 12 after the movement is updated to the position of the piston 12 represented by the learning zero position.

[0057] When the vehicle control system determines that the current vehicle has a pressure relief demand and executes the pressure relief action, and when the pressure relief stroke that the piston 12 needs to move is calculated through the hydraulic pressure information, the pressure relief action is then executed through the piston 12. During this process, the piston 12 moves the pressure relief stroke toward the direction of the motor 100 at the learning zero position to complete the pressure relief action; after the piston 12 completes the pressure relief action, since the piston 12 has moved the pressure relief stroke toward the direction of the motor 100, if the piston 12 moves to the learning zero position again, it is a pressure building action, which will increase the hydraulic pressure in the pressure building chamber 11. Therefore, after the piston 12 moves the pressure relief stroke toward the direction of the motor 100, the control system updates the position of the piston 12 after the pressure relief stroke is moved to the new learning zero position, and the piston 12 stays at the position after the pressure relief stroke is moved.

[0058] Since the position of the piston 12 represented by the learning zero position is updated after the pressure relief action is performed, the pressure relief process after the next pressure build-up is performed based on the new learning zero position.

[0059] Combination Figure 2 As shown, in some embodiments, after the vehicle is started, the control system first sets a learning zero position in the pressure chamber 11, that is, in step S100, a learning zero position is set in the pressure chamber 11. After the vehicle is started, the control system controls the opening of the CSV separation valve 300 and the PSV separation valve 400, and then drives the piston 12 to move to the mechanical zero position toward the direction of the motor 100 through the motor 100, and then drives the piston 12 to move the learning zero stroke in the direction away from the motor 100, and sets the position of the piston 12 after moving the learning zero stroke as the learning zero position.

[0060] It can be understood that driving the piston 12 to move to the mechanical zero position is actually a "return to zero" process. Then driving the piston 12 to move the learning zero stroke can make the control system monitor the position of the piston 12 more accurate, and ensure that the position of the first learning zero position can remain consistent each time the vehicle is started.

[0061] In some embodiments, in the above step S200, the control system should first set a pressure relief threshold for the pressure building chamber 11; when the piston 12 completes the pressure building action and returns to the zero position, the liquid pressure information of the pressure building chamber 11 is detected by the pressure sensor arranged at the pressure building cylinder 10, and the liquid pressure information is compared with the pressure relief threshold. When the liquid pressure value represented by the liquid pressure information exceeds the liquid pressure value represented by the pressure relief threshold, it indicates that there is residual liquid pressure in the pressure building chamber 11 that needs to be relieved, and there is a pressure relief demand at this time, and it is judged that the pressure relief request is activated.

[0062] In some embodiments, in the above step S200, when the pressure relief request is activated, it is also necessary to determine whether the current vehicle has a braking demand through the current vehicle status information. If the current vehicle has no braking demand, it is determined to perform the pressure relief action.

[0063] The current vehicle status information in this embodiment specifically includes the current vehicle speed, braking information, throttle information and EPB status information. The specific judgment of whether there is a braking demand can be divided into the following situations:

[0064] When there is no braking information but there is throttle information, it is determined that the current vehicle has no braking demand;

[0065] When there is no braking information and throttle information, but the wheels of the current vehicle are stationary and the EPB status information is in the clamped state, it is determined that the current vehicle has no braking demand;

[0066] Outside the above two situations, the control system determines that the vehicle currently has a braking demand.

[0067] When the control system determines that the pressure relief request is activated and there is no braking demand on the current vehicle, the control system further determines to perform a pressure relief action through the piston 12 .

[0068] In some embodiments, when the piston 12 completes the pressure building action and returns to the zero position, the hydraulic pressure information of the pressure building chamber 11 is detected by a pressure sensor arranged at the pressure building cylinder 10. At this time, the hydraulic pressure value represented by the hydraulic pressure information is compared with the hydraulic pressure value represented by the pressure relief threshold, and the range in which the hydraulic pressure value represented by the hydraulic pressure information exceeds the hydraulic pressure value represented by the pressure relief threshold is obtained. The part of the hydraulic pressure value represented by the hydraulic pressure information that exceeds the hydraulic pressure value represented by the pressure relief threshold is the residual hydraulic pressure in the pressure building chamber 11. Then, based on the residual hydraulic pressure, the control system calculates the pressure relief stroke that the piston 12 needs to move toward the direction of the motor 100, so as to relieve the residual hydraulic pressure through the movement of the piston 12, thereby "digesting" the residual hydraulic pressure in the pressure building chamber 11.

[0069] In some embodiments, in the above step S400, when performing the pressure relief action, it is also necessary to determine the size of the pressure relief stroke, the total pressure relief stroke and the learning zero stroke. Among them, since the software zero position is farther away from the motor 100 than the mechanical zero position, the total pressure relief stroke is smaller than the learning zero stroke.

[0070] Specifically, when the pressure relief stroke is less than the total pressure relief stroke, combined with Figure 3 As shown, the piston 12 whose actual position is at the learning zero position moves toward the direction of the motor 100 by the corresponding pressure relief stroke to realize the relief of the residual hydraulic pressure, and the actual position of the piston 12 after the pressure relief stroke is updated to the position of the piston 12 represented by the learning zero position; and due to the update of the position of the piston 12 represented by the learning zero position, the distance between the updated learning zero position and the software zero position has changed, that is, the total pressure relief stroke has also been updated, and then the subsequent process of pressure relief after the piston 12 builds up pressure is based on the updated learning zero position and the updated total pressure relief stroke.

[0071] When the pressure relief stroke is greater than the total pressure relief stroke and less than the zero stroke, Figure 4 As shown, that is, the piston 12 has performed multiple pressure relief processes, and the total pressure relief stroke has been continuously shortened under the accumulation of multiple pressure relief strokes, until the pressure relief stroke calculated by the control system in this pressure relief process is greater than the total pressure relief stroke and less than the learning zero stroke; at this time, the control system controls the piston 12 to move to the mechanical zero position, and then drives the piston 12 to move the learning zero stroke in the direction away from the motor 100, and updates the actual position of the piston 12 after moving the learning zero stroke to the learning zero position, and re-determines whether to perform the pressure relief action based on the updated learning zero position;

[0072] When the pressure relief stroke is greater than the zero stroke, Figure 5 As shown, at this time, the movement of the piston 12 in the pressure-building chamber 11 can no longer meet the pressure relief demand of the residual hydraulic pressure, and it is necessary to cooperate with the existing pressure relief circuit of the vehicle to relieve the residual hydraulic pressure; specifically, the piston 12 first moves to the mechanical zero position in the pressure-building chamber 11, that is, after "digesting" part of the residual liquid pressure in the pressure-building chamber 11, the residual hydraulic pressure is relieved through the existing pressure relief circuit of the vehicle, such as opening the OV valve 200 to relieve the residual liquid pressure; then the piston 12 at the mechanical zero position moves the learning zero stroke in the direction away from the motor 100, and the position of the piston 12 after moving the learning zero stroke is updated to the new learning zero position. It can be understood that when the pressure relief stroke is greater than the learning zero stroke, the movement of the piston 12 from the learning zero position to the mechanical zero position is the pressure relief stroke. It is worth mentioning that in this embodiment, the pressure relief circuit is used to assist in pressure relief only when the residual liquid pressure is too large, which can better reduce the frequency of use of the pressure relief circuit.

[0073] In some embodiments, when performing a pressure relief action, the braking requirements of the current vehicle should also be met first. That is, when there is a braking demand for the current vehicle, the piston 12 should immediately stop moving toward the motor 100 and move away from the motor 100 to perform a pressure building action.

[0074] Specifically, when performing the pressure relief action, the control system will also obtain the current vehicle status information in real time, and determine whether the current vehicle has a braking demand based on the current vehicle speed, braking information, throttle information and EPB status information obtained in real time. If it is determined that the current vehicle has a braking demand, the pressure relief action performed by the piston 12 is interrupted, so that the piston 12 turns and moves in the pressure building chamber 11 to perform the pressure building action.

[0075] In some embodiments, when the piston 12 moves toward the direction of the motor 100 to perform a pressure relief action, if the current vehicle has a braking demand, the piston 12 immediately stops moving toward the direction of the motor 100, so that the piston 12 turns and moves in the pressure building chamber 11 to perform a pressure building action, giving priority to meeting the braking demand of the current vehicle; in this process, the position of the piston 12 when it changes from performing a pressure relief action to performing a pressure building action is updated to a new learning zero position, so that after the piston 12 completes the pressure building action, the control system can determine whether to perform a pressure relief action based on the updated new learning zero position.

[0076] Second, combining Figure 6 As shown, this embodiment provides an electronic hydraulic brake system, which includes an oil pot 500, a CSV separation valve 300, a PSV separation valve 400, a pressure-building cylinder 10, and a pressure relief circuit; wherein the CSV separation valve 300 is respectively connected to the oil pot 500, the pressure-building cylinder 10, and the pressure relief circuit; the PSV separation valve 400 is respectively connected to the oil pot 500, the pressure-building cylinder 10, and the pressure relief circuit, and the PSV separation valve 400 is connected to the CSV separation valve 300. Specifically, the pressure relief circuit in this embodiment includes an OV valve 200.

[0077] In this embodiment, after the vehicle is started, the position where the piston 12 moves to the bottom in the pressure-building chamber 11 toward the motor 100 is set as the mechanical zero position; based on the mechanical zero position, the position where the piston 12 at the mechanical zero position moves 0.8 mm away from the motor 100 is set as the software zero position, and the position where the piston 12 at the mechanical zero position moves 3 mm away from the motor 100 is set as the academic zero position.

[0078] Therefore, the zero stroke in this embodiment is 3 mm, and the total pressure relief stroke is 2.2 mm.

[0079] When the control system performs the pressure relief action through the piston 12, it specifically includes:

[0080] Under the premise of learning zero position and updating the total pressure relief stroke, when the pressure relief stroke is less than the total pressure relief stroke, if Figure 3 As shown, the piston 12 moves the pressure relief stroke toward the motor 100 to complete the pressure relief action, and at the same time, the learning zero position is updated to the actual position of the piston 12 after moving the pressure relief stroke, and the total pressure relief stroke is updated to the distance between the updated learning zero position and the software zero position.

[0081] Under the premise of learning zero position and updating the total pressure relief stroke, when the pressure relief stroke is greater than the total pressure relief stroke and less than the learning zero stroke, Figure 4 As shown, the control system controls the piston 12 to move to the mechanical zero position, and then drives the piston 12 to move the learning zero stroke in the direction away from the motor 100, updates the actual position of the piston 12 after moving the learning zero stroke to the new learning zero position, and re-determines whether to perform the pressure relief action based on the updated learning zero position.

[0082] When the pressure relief stroke is greater than the zero stroke of 3mm, Figure 5 As shown, the piston 12 first moves to the mechanical zero position in the pressure building chamber 11, that is, after "digesting" part of the residual liquid pressure in the pressure building chamber 11, the residual liquid pressure is released through the vehicle's existing pressure relief circuit. Specifically, the residual liquid pressure is released by opening the OV valve 200; then, the piston 12 at the mechanical zero position moves the learning zero stroke in the direction away from the motor 100, and the position of the piston 12 after moving the learning zero stroke is updated to a new learning zero position.

[0083] In conclusion, the above is only a preferred embodiment of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the patent of the present invention.

Claims

1. A method for relieving residual brake fluid pressure, characterized in that: include, A learning zero position is set in the pressure building chamber, the position of the piston represented by the learning zero position is farther away from the motor than the position of the piston represented by the software zero position, and the distance between the learning zero position and the software zero position is set as the total pressure relief stroke; Determining whether to activate a pressure relief request based on the hydraulic pressure information of the pressure-building chamber when the actual position of the piston is at the learning zero position and determining the braking demand of the current vehicle based on the current vehicle state information, and determining whether to perform a pressure relief action based on the pressure relief request and the braking demand; Acquiring a pressure relief stroke of the piston that satisfies a pressure relief requirement based on the hydraulic pressure information; When performing the pressure relief action, and when the pressure relief stroke is less than the total pressure relief stroke, the piston at the learning zero position moves the pressure relief stroke toward the direction of the motor, and the position of the piston after movement is updated to the position of the piston represented by the learning zero position.

2. The method for relieving residual brake fluid pressure according to claim 1, characterized in that: When setting a zero position in the pressure chamber, it includes: Open the CSV separation valve and the PSV separation valve, wherein the CSV separation valve is arranged between the brake master cylinder and the IV inlet valve of the wheel cylinder, and the PSV separation valve is arranged between the pressure-building cylinder and the IV inlet valve of the wheel cylinder, and when the piston moves to the mechanical zero position, it moves away from the motor by a learning zero stroke, and sets the actual position of the piston at this time as the learning zero position; The mechanical zero position represents the position where the piston moves to the bottom in the pressure building chamber in the direction toward the motor.

3. The method for relieving residual brake fluid pressure according to claim 1, characterized in that: Executing the judgment of whether to activate the pressure relief request based on the hydraulic pressure information of the pressure-building chamber when the actual position of the piston is at the learning zero position and judging the braking demand of the current vehicle based on the current vehicle state information, and judging whether to perform the pressure relief action based on the pressure relief request and the braking demand, specifically includes: Setting a pressure relief threshold of the pressure-building chamber; Acquiring hydraulic pressure information of the pressure building chamber; It is determined whether to activate a pressure relief request based on the pressure relief threshold and the hydraulic pressure information.

4. The method for relieving residual brake fluid pressure according to claim 3, characterized in that: Executing the judgment of whether to activate the pressure relief request based on the hydraulic pressure information of the pressure-building chamber when the actual position of the piston is at the learning zero position and judging the braking demand of the current vehicle based on the current vehicle state information, and judging whether to perform the pressure relief action based on the pressure relief request and the braking demand, specifically includes: The current vehicle speed, braking information, throttle information and EPB status information are acquired as the status information of the current vehicle, and the braking demand of the current vehicle is determined based on the status information of the current vehicle.

5. The method for relieving residual brake fluid pressure according to claim 3, characterized in that: Executing the pressure relief stroke of the piston that meets the pressure relief requirement based on the hydraulic pressure information specifically includes: The pressure relief stroke is calculated based on the hydraulic pressure information and the pressure relief threshold.

6. The method for relieving residual brake fluid pressure according to claim 2, characterized in that: When performing the pressure relief action, and when the pressure relief stroke is greater than the total pressure relief stroke and less than the zero stroke, the CSV separation valve and the PSV separation valve are opened, the CSV separation valve is arranged between the brake master cylinder and the IV inlet valve of the wheel cylinder, and the PSV separation valve is arranged between the pressure building cylinder and the IV inlet valve of the wheel cylinder; The piston moves to the mechanical zero position, and then moves the learning zero stroke in a direction away from the motor, and the position of the piston after the movement is updated to the position of the piston represented by the learning zero position.

7. The method for relieving residual brake fluid pressure according to claim 6, characterized in that: When performing the pressure relief action, and when the pressure relief stroke is greater than the mechanical zero stroke, the pressure is released by moving the piston to the mechanical zero position and the pressure relief circuit of the current vehicle; When the piston moves to the mechanical zero position, the piston is moved toward the direction away from the motor to the learning zero stroke, and the position of the piston after the movement is updated to the position of the piston represented by the learning zero position.

8. The method for relieving residual brake fluid pressure according to claim 4, characterized in that: When performing a pressure relief action, when it is determined based on the status information of the current vehicle that the current vehicle has a braking demand, the piston changes from performing a pressure relief action to performing a pressure building action.

9. The method for relieving residual brake fluid pressure according to claim 8, characterized in that: When the piston changes from performing a pressure relief action to performing a pressure building action, specifically, The position of the piston when it is switched is updated to the position of the piston represented by the learning zero position.

10. An electronic hydraulic brake system, characterized in that: The brake system includes an oil tank, CSV separation valve, PSV separation valve, brake master cylinder, wheel cylinder, IV inlet valve, OV outlet valve and pressure building cylinder; The CSV separation valve is arranged between the brake master cylinder and the IV inlet valve of the wheel cylinder, while the PSV separation valve is arranged between the pressure building cylinder and the IV inlet valve of the wheel cylinder, wherein the oil pot is connected to the brake master cylinder and the pressure building cylinder respectively, and the wheel cylinder is connected to the OV outlet valve for pressure relief; The braking system adopts the residual brake fluid pressure relief method described in any one of claims 1-9.

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