Multi-working-condition hydraulic braking system of vehicle

Abstract

The invention provides a multi-working-condition hydraulic braking system for a vehicle. The multi-working-condition hydraulic braking system comprises a controller, a hydraulic subsystem, an oil control subsystem and a braking subsystem. The hydraulic subsystem comprises a motor, a liquid storage tank, a hydraulic pump, an overflow valve, a one-way valve, an energy accumulator, a first pressure sensor, a first isolating valve and a second isolating valve; the second isolation valve is configured to be in a normally-open state, and when the braking subsystem does not conduct braking, oil leaked from an outlet of the first isolation valve flows back to the liquid storage tank through the second isolation valve, so that the oil leaked from an outlet of the first isolation valve ZLV1 can be prevented from flowing into the braking subsystem, and the braking effect of the braking subsystem is improved. According to the technical scheme, the brake caliper in the brake subsystem is prevented from continuously acting on the brake disc, dragging torque cannot be generated, abrasion to the brake cylinder is reduced, vehicle running resistance is small, vehicle oil consumption is reduced, power performance is improved, the response precision of the brake subsystem can be improved, and vehicle running safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle braking, and in particular to a vehicle multi-working-mode hydraulic braking system. Background Art

[0002] As a core component for ensuring driving safety, the reliability and stability of a vehicle's hydraulic braking system are crucial. In traditional multi-mode hydraulic braking system designs, the accumulator, acting as a pressure energy storage element, is filled with fluid from a hydraulic pump. A check valve and an isolation valve are then used to seal the pressurized oil, ensuring stable hydraulic power to the wheel cylinders under varying braking conditions.

[0003] However, research has found that isolation valves often fail to completely seal. After prolonged operation, pressurized oil can leak through the isolation valve into the brake cylinder. This leakage can lead to abnormal pressure buildup in the brake cylinder, which in turn forces the brake caliper to continuously apply pressure to the brake disc, generating unnecessary drag torque. This can lead to increased wear on the brake cylinder, higher fuel consumption, and reduced safety. Summary of the Invention

[0004] The present invention provides a vehicle multi-working mode hydraulic brake system, which is used to solve the defects in the prior art that leakage of an isolation valve causes greater wear of the brake cylinder, higher vehicle fuel consumption and poor safety.

[0005] In one aspect, the present invention provides a vehicle multi-operating-mode hydraulic braking system, which includes a controller, a hydraulic subsystem, an oil control subsystem, and a braking subsystem; The hydraulic subsystem includes a motor, a fluid storage tank, a hydraulic pump, a relief valve, a one-way valve, an accumulator, a first pressure sensor, a first isolation valve and a second isolation valve; The motor is electrically connected to the hydraulic pump and the controller; The inlet of the hydraulic pump and the outlet of the relief valve are in communication with the liquid storage tank, and the outlet of the hydraulic pump is in communication with the inlet of the one-way valve and the inlet of the relief valve; The outlet of the one-way valve and the inlet of the first isolation valve are in communication with the accumulator; the first pressure sensor is used to detect the pressure of the accumulator; The outlet of the first isolation valve is in communication with the oil control subsystem and the inlet of the second isolation valve; The oil control subsystem is in communication with the brake subsystem; The outlet of the second isolation valve is connected to the fluid storage tank; wherein, the second isolation valve is configured to be in a normally open state, so that when the braking subsystem is not braking, the oil leaked from the outlet of the first isolation valve flows back to the fluid storage tank through the second isolation valve.

[0006] According to a vehicle multi-working mode hydraulic brake system provided by the present invention, the oil control subsystem includes a first proportional valve, a second proportional valve, a first pressure relief valve, a second pressure relief valve and a balancing valve; the braking subsystem includes a first service brake cylinder and a second service brake cylinder; The outlet of the first proportional valve is in communication with the inlet of the first pressure relief valve, the first opening of the balancing valve, and the first service brake cylinder; The outlet of the second proportional valve is in communication with the inlet of the second pressure relief valve, the second opening of the balancing valve and the second service brake cylinder; The outlet of the first pressure relief valve and the outlet of the second pressure relief valve are in communication with the liquid storage tank; The controller is configured to control the braking or non-braking of the braking subsystem by controlling the working state of the target valve and the motor according to different working conditions; wherein the target valve includes at least one of the first isolation valve, the second isolation valve, the first proportional valve, the second proportional valve, the first pressure relief valve, the second pressure relief valve and the balancing valve.

[0007] According to a vehicle multi-working condition hydraulic brake system provided by the present invention, the working conditions include an accumulator fluid replenishing working condition; When the pressure value detected by the first pressure sensor is less than a first preset pressure value, the motor is started, so that the motor drives the hydraulic pump to replenish the accumulator, until the pressure value detected by the first pressure sensor is greater than a second preset pressure value, and the motor is controlled to stop running; The first isolation valve, the second isolation valve, the first proportional valve, the second proportional valve, the first pressure relief valve, the second pressure relief valve and the balancing valve are all de-energized.

[0008] According to a vehicle multi-working condition hydraulic braking system provided by the present invention, the working conditions include an unbraked driving condition; When there is no service brake percentage instruction, the first isolation valve, the second isolation valve, the first proportional valve, the second proportional valve, the first pressure relief valve, the second pressure relief valve and the balancing valve are all de-energized, and the motor determines whether to work based on the pressure of the accumulator. The first proportional valve and the second proportional valve both output a first adjustment proportional signal that is less than a preset proportion, so that the pressure of the first service brake cylinder and the pressure of the second service brake cylinder are both less than or equal to a third preset pressure.

[0009] According to the present invention, a multi-working-condition hydraulic braking system for a vehicle is provided, wherein the working conditions include a boost braking condition under a straight road condition and a decompression braking condition under a straight road condition; Under the boost braking condition on a straight road, the first isolation valve is energized and opened, the second isolation valve is energized and closed, the first and second proportional valves output second adjustment proportional signals, and the balancing valve is de-energized and remains open, so that the pressure of the first service brake cylinder and the pressure of the second service brake cylinder both meet the pressure corresponding to the second adjustment proportional signal; Under the straight road pressure reduction braking condition, the first isolation valve is powered off and closed, the second isolation valve is powered on and closed, the first proportional valve and the second proportional valve output a third adjustment proportional signal, the balancing valve is de-energized and remains conductive, the first pressure relief valve and the second pressure relief valve are intermittently powered on and conductive, so that the pressure of the first service brake cylinder and the pressure of the second service brake cylinder both meet the pressure corresponding to the third adjustment proportional signal; wherein, the pressure corresponding to the third adjustment proportional signal is less than the pressure corresponding to the second adjustment proportional signal.

[0010] According to a vehicle multi-working condition hydraulic braking system provided by the present invention, the working condition includes a long downhill braking condition; When it is detected that the vehicle performs boost braking for a duration greater than a first preset duration and the change in the pedal depression position is less than a preset change value, the first proportional valve and the second proportional valve are adjusted to a set control current, the first isolation valve is de-energized and closed, the second isolation valve is energized and closed, and the first pressure relief valve and the second pressure relief valve are de-energized and remain closed; When it is detected that the change value of the pedal depressed position is greater than the preset change value, the long downhill braking condition is released and the condition is switched according to the change value of the pedal depressed position.

[0011] According to a vehicle multi-working condition hydraulic braking system provided by the present invention, the working conditions include a turning braking condition, and the turning braking condition includes a turning boost braking condition and a turning decompression braking condition; In the turning braking condition, the pressure of the inner service brake cylinder and the pressure of the outer service brake cylinder are distributed according to the turning direction, so that the pressure of the outer service brake cylinder is greater than the pressure of the inner service brake cylinder; wherein, when the turning direction is left, the first service brake cylinder is the inner service brake cylinder and the second service brake cylinder is the outer service brake cylinder; when the turning direction is right, the first service brake cylinder is the outer service brake cylinder and the second service brake cylinder is the inner service brake cylinder; In a cornering boost braking condition, the first isolation valve is energized and turned on, the second isolation valve is energized and closed, the first pressure relief valve and the second pressure relief valve are de-energized and remain closed, the balancing valve is energized and closed, the first proportional valve outputs a fourth adjustment proportional signal, and the second proportional valve and the first proportional valve output a fifth adjustment proportional signal, so that the pressure of the first service brake cylinder is different from the pressure of the second service brake cylinder; Under the cornering decompression braking condition, the first isolation valve is powered off and closed, the second isolation valve is powered on and closed, the balancing valve is powered on and closed, the first proportional valve outputs the sixth adjustment proportional signal, and the second proportional valve outputs the seventh adjustment proportional signal, so that the pressure of the first service brake cylinder is different from the pressure of the second service brake cylinder, and the first pressure relief valve and the second pressure relief valve are intermittently powered on and turned on, so that the pressure of the first service brake cylinder meets the pressure corresponding to the sixth adjustment proportional signal, and the pressure of the second service brake cylinder meets the pressure corresponding to the seventh adjustment proportional signal.

[0012] According to a vehicle multi-working-mode hydraulic brake system provided by the present invention, the system further includes a second pressure sensor and a third pressure sensor; The second pressure sensor is used to detect the pressure of the first service brake cylinder, and the third pressure sensor is used to detect the pressure of the second service brake cylinder; The operating conditions include a continuous braking automatic decompression operating condition; If the pressure of the first service brake cylinder is greater than the required pressure of the first service brake cylinder, and / or the pressure of the second service brake cylinder is greater than the required pressure of the second service brake cylinder, automatically reducing pressure; The first isolation valve is powered off and closed, the second isolation valve is powered on and closed, the first pressure relief valve and the second pressure relief valve are intermittently powered on and connected, and the balancing valve maintains the state before automatic decompression.

[0013] According to a vehicle multi-working condition hydraulic brake system provided by the present invention, the working condition includes a pressure maintaining working condition; Under the pressure maintaining condition, if the pressure of the first service brake cylinder is greater than the fourth preset pressure and less than the required pressure of the first service brake cylinder, the first isolation valve is controlled to be energized and turned on, the second isolation valve is energized and closed, the balancing valve is energized and closed, the first proportional valve is energized and closed, and the second proportional valve maintains its original state to maintain the pressure of the first service brake cylinder; if the pressure of the second service brake cylinder is greater than the fourth preset pressure and less than the required pressure of the second service brake cylinder, the first isolation valve is controlled to be energized and turned on, the second isolation valve is energized and closed, the balancing valve is energized and closed, the second proportional valve is energized and closed, and the first proportional valve maintains its original state to maintain the pressure of the second service brake cylinder.

[0014] According to a vehicle multi-working condition hydraulic brake system provided by the present invention, the working conditions include a pressure-maintaining followed by a pressure-reducing working condition; Under the pressure-maintaining and pressure-reducing working condition, if the pressure of the first service brake cylinder is greater than the fifth preset pressure and less than the fourth preset pressure after the first service brake cylinder enters the pressure-maintaining working condition for the second preset time, the first isolation valve is controlled to be energized and turned on, the second isolation valve is energized and closed, the balancing valve is energized and closed, the first proportional valve is energized and closed, the second proportional valve maintains its original state, and the first pressure relief valve is intermittently energized and turned on to relieve the pressure of the first service brake cylinder; if the pressure of the second service brake cylinder is greater than the fifth preset pressure and less than the fourth preset pressure after the first service brake cylinder enters the pressure-maintaining working condition for the second preset time, the first isolation valve is controlled to be energized and turned on, the second isolation valve is energized and closed, the balancing valve is energized and closed, the second proportional valve is energized and closed, the first proportional valve maintains its original state, and the second pressure relief valve is intermittently energized and turned on to relieve the pressure of the second service brake cylinder.

[0015] The vehicle multi-mode hydraulic braking system provided by the present invention is configured by arranging a normally open second isolation valve ZLV2 between the outlet side of the first isolation valve ZLV1 and the fluid storage tank C. In this way, when the braking subsystem is not braking, the oil leaked from the outlet of the first isolation valve ZLV1 flows back to the fluid storage tank C through the second isolation valve ZLV2, thereby preventing the oil leaked from the outlet of the first isolation valve ZLV1 from flowing into the braking subsystem, avoiding the brake caliper in the braking subsystem from continuously acting on the brake disc, and not generating drag torque, thereby reducing the wear on the brake cylinder, resulting in less vehicle driving resistance, reducing vehicle fuel consumption, improving power performance, and improving the response accuracy of the braking subsystem, thereby improving the safety of vehicle driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 1 is a schematic structural diagram of a vehicle multi-working-mode hydraulic brake system provided by an embodiment of the present invention; Figure 2 This is the principle diagram of the unbraked driving condition; Figure 3 This is the principle diagram of the boost braking condition on straight and level roads; Figure 4 This is the principle diagram of the decompression braking condition on straight and level roads; Figure 5 This is the principle diagram of the long downhill braking condition; Figure 6 This is the principle diagram of the cornering boost braking condition; Figure 7 This is the principle diagram of the cornering decompression braking condition; Figure 8 This is the principle diagram of the braking condition when the accumulator pressure is insufficient; Figure 9 This is the principle diagram of the pressure holding condition corresponding to the first service brake cylinder L; Figure 10 This is the principle diagram of the pressure-maintaining working condition corresponding to the second service brake cylinder R; Figure 11 This is a schematic diagram of the decompression condition corresponding to the first service brake cylinder L; Figure 12 It is a principle diagram of the decompression working condition corresponding to the second service brake cylinder R. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0019] Figure 1 FIG. 1 is a schematic structural diagram of a vehicle multi-mode hydraulic brake system provided by an embodiment of the present invention. Figure 1 As shown, the multi-mode hydraulic braking system for a vehicle of this embodiment may include a controller (not shown), a hydraulic subsystem, an oil control subsystem, and a braking subsystem. The hydraulic subsystem includes a motor M, a fluid reservoir C, a hydraulic pump PUMP, a relief valve RV, a one-way valve CV, an accumulator ACC, a first pressure sensor PU1, a first isolation valve ZLV1, and a second isolation valve ZLV2.

[0020] In a specific implementation process, the motor M is electrically connected to the hydraulic pump PUMP and the controller; the inlet of the hydraulic pump PUMP and the outlet of the overflow valve RV are connected to the fluid storage tank C, and the outlet of the hydraulic pump PUMP is connected to the inlet of the one-way valve CV and the inlet of the overflow valve RV; the outlet of the one-way valve CV and the inlet of the first isolation valve ZLV1 are connected to the accumulator ACC; the first pressure sensor PU1 is used to detect the pressure of the accumulator ACC; the outlet of the first isolation valve ZLV1 is connected to the oil control subsystem and the inlet of the second isolation valve ZLV2; the oil control subsystem is connected to the braking subsystem; the outlet of the second isolation valve ZLV2 is connected to the fluid storage tank C.

[0021] In one specific implementation, the second isolation valve ZLV2 is configured to be normally open. When the brake subsystem is not braking, oil leaking from the outlet of the first isolation valve ZLV1 flows back to the fluid reservoir C through the second isolation valve ZLV2. This prevents oil leaking from the outlet of the first isolation valve ZLV1 from flowing into the brake subsystem, preventing the brake caliper from continuously acting on the brake disc in the brake subsystem, thus preventing drag torque and reducing wear on the brake cylinder. This reduces vehicle driving resistance, reduces fuel consumption, improves power performance, and enhances the response accuracy of the brake subsystem, thereby improving vehicle driving safety.

[0022] Continue to see Figure 1 The oil control subsystem includes a first proportional valve EV1, a second proportional valve EV2, a first pressure relief valve AV1, a second pressure relief valve AV2 and a balancing valve BV; the braking subsystem includes a first service brake cylinder L and a second service brake cylinder R; The outlet of the first proportional valve EV1 is in communication with the inlet of the first pressure relief valve AV1, the first opening of the balancing valve BV, and the first service brake cylinder L; The outlet of the second proportional valve EV2 is connected to the inlet of the second pressure relief valve AV2, the second opening of the balancing valve BV and the second service brake cylinder R; The outlet of the first pressure relief valve AV1 and the outlet of the second pressure relief valve AV2 are in communication with the liquid storage tank C; In a specific implementation process, the controller is configured to control the braking or non-braking of the braking subsystem by controlling the working state of the target valve and the motor M according to different working conditions; wherein, the target valve includes at least one of the first isolation valve ZLV1, the second isolation valve ZLV2, the first proportional valve EV1, the second proportional valve EV2, the first pressure relief valve AV1, the second pressure relief valve AV2 and the balancing valve BV.

[0023] Specifically, the working condition includes the accumulator ACC refilling working condition. Figure 1Under this operating condition, when the pressure value detected by the first pressure sensor PU1 is less than a first preset pressure value (which may be 12 MPa), the motor M is started, causing the motor M to drive the hydraulic pump PUMP to replenish the accumulator ACC until the pressure value detected by the first pressure sensor PU1 is greater than a second preset pressure value (which may be 14 MPa), and the motor M is controlled to stop running; wherein, the first isolation valve ZLV1, the second isolation valve ZLV2, the first proportional valve EV1, the second proportional valve EV2, the first pressure relief valve AV1, the second pressure relief valve AV2 and the balancing valve BV are all de-energized. For the corresponding oil flow path, see Figure 1 Middle red part.

[0024] That is, under this operating condition, after the vehicle is started, the system confirms the status of the accumulator ACC and obtains the pressure value detected by the first pressure sensor PU1 (i.e., the pressure value of the accumulator ACC). Simultaneously, when the vehicle is operating normally and the pressure value of the accumulator ACC is detected to be less than 12 MPa, the accumulator ACC refilling condition is initiated. At this time, the first isolation valve ZLV1, the second isolation valve ZLV2, the first pressure relief valve AV1, the second pressure relief valve AV2, the first proportional valve EV1, the second proportional valve EV2, and the balancing valve BV are all de-energized and maintain normal operation. The motor M is energized and rotates, driving the gear pump to refill the accumulator ACC until the pressure exceeds 14 MPa and stops.

[0025] It should be noted that the accumulator ACC refilling operation is described separately here. In actual applications, the accumulator ACC refilling operation can also be performed simultaneously in other operating conditions, which will not be described one by one here.

[0026] In a specific implementation process, the working condition includes an unbraked driving condition; in this working condition, when there is no service brake percentage instruction, the first isolation valve ZLV1, the second isolation valve ZLV2, the first proportional valve EV1, the second proportional valve EV2, the first pressure relief valve AV1, the second pressure relief valve AV2 and the balance valve BV are all de-energized, and the motor M determines whether to work based on the pressure of the accumulator. The first proportional valve EV1 and the second proportional valve EV2 both output a first adjustment ratio signal that is less than a preset ratio (the value corresponding to which may be 0), so that the pressure of the first service brake cylinder L and the pressure of the second service brake cylinder R are both less than or equal to a third preset pressure (the third preset pressure may be 0). For details, please refer to Figure 2 , Figure 2 This is the principle diagram of the unbraked driving condition. Figure 2 The medium pressure oil is blocked by the one-way valve CV and the first isolation valve ZLV1.

[0027] That is to say, the controller does not output the "service brake percentage instruction" (service brake percentage = 0). At this time, the motor M, the first isolation valve ZLV1, the second isolation valve ZLV2, the first pressure relief valve AV1, the second pressure relief valve AV2, the balancing valve BV, and the motor M are all de-energized, the output signal ratio of the first proportional valve EV1 and the second proportional valve EV2 is 0, the service brake cylinder is unloaded, and the pressure in the service brake cylinder is close to 0; 12MPa≤the pressure of the first parking brake cylinder / the pressure of the second parking brake cylinder≤14MPa, and the parking brake cylinder oil circuit maintains pressure.

[0028] In a specific implementation, the operating conditions include a boost braking condition on a straight road and a decompression braking condition on a straight road, wherein the straight road condition here refers to a road condition in a conventional scenario, for example, excluding road conditions such as long downhill slopes and curves.

[0029] Figure 3 This is the principle diagram of the boost braking condition on straight road conditions, such as Figure 3 As shown, under the boost braking condition on the straight road, the first isolation valve ZLV1 is energized and turned on, the second isolation valve ZLV2 is energized and closed, the first proportional valve EV1 and the second proportional valve EV2 output the second adjustment proportional signal, and the balancing valve BV is not energized and remains on, so that the pressure of the first service brake cylinder L and the pressure of the second service brake cylinder R both meet the pressure corresponding to the second adjustment proportional signal. The pressure of the first service brake cylinder L and the pressure of the second service brake cylinder R can be expressed as: 10Mpa×brake signal percentage %±0.5Mpa. Among them, the brake signal percentage % is the value corresponding to the second adjustment proportional signal. Among them, under this condition, the flow condition of the oil circuit, such as Figure 3 Shown by the red line.

[0030] In other words, under this operating condition, the second isolation valve ZLV2 is energized to close, while the first isolation valve ZLV1 is energized to open and output fluid to the first and second proportional valves EV1 and EV2. The first and second proportional valves EV1 and EV2 output a certain percentage of pressure based on the proportional adjustment signal from the controller. At this point, the valves are normally open, maintaining a balanced pressure of 10 MPa * brake signal percentage ± 0.5 MPa for both left and right wheel brake cylinders. When the required pressure is reached, the first isolation valve ZLV1 opens and maintains the pressure. During the brake holding process, the brake pressure may drop due to leakage from the hydraulic valve. When the brake pressure falls below the required pressure, the first isolation valve ZLV1 is energized to open and replenish fluid to the brake cylinders. Both the first and second pressure relief valves AV1 and AV2 are deenergized and remain closed.

[0031] Figure 4 This is the principle diagram of the decompression braking condition on straight road conditions. Figure 4As shown, under the straight road decompression braking condition, the first isolation valve ZLV1 is powered off and closed, the second isolation valve ZLV2 is powered on and closed, the first proportional valve EV1 and the second proportional valve EV2 output the third adjustment ratio signal, the balancing valve BV is not powered and remains conductive, the first pressure relief valve AV1 and the second pressure relief valve AV2 are intermittently powered on and conductive, so that the pressure of the first service brake cylinder L and the pressure of the second service brake cylinder R both meet the pressure corresponding to the third adjustment ratio signal; wherein, the pressure corresponding to the third adjustment ratio signal is less than the pressure corresponding to the second adjustment ratio signal. Under this condition, the flow condition of the oil circuit is as follows: Figure 4 Shown by the red line.

[0032] That is to say, when the decompression braking program given by the controller is received and the "service brake percentage instruction" begins to decrease, the first isolation valve ZLV1 is powered off and closed, and the second isolation valve ZLV2 is powered on and closed to ensure that the pressure in the brake cylinder does not increase. The first proportional valve EV1 and the second proportional valve EV2 output a certain percentage of pressure according to the adjustment proportion signal given by the controller. At this time, the balance is normally open. The first pressure relief valve AV1 and the second pressure relief valve AV2 adjust the opening time through pulse width modulation (PWM) technology to slowly reduce the pressure in the brake cylinder until the pressure specified by the "service brake percentage instruction" is met. At this time, the pressure of the left and right wheel brake cylinders are both = 10MPa*brake signal percentage%±0.5MPa.

[0033] In a specific implementation, the operating condition includes a long downhill braking condition. Figure 5 This is a schematic diagram of the long downhill braking condition. When it is detected that the vehicle performs boost braking for a period longer than a first preset period, and the change in the pedal depression position is less than a preset change value, the first proportional valve EV1 and the second proportional valve EV2 are adjusted to the set control current, the first isolation valve ZLV1 is powered off and closed, the second isolation valve ZLV2 is powered on and closed, and the first pressure relief valve AV1 and the second pressure relief valve AV2 are de-energized and remain closed; when it is detected that the change in the pedal depression position is greater than the preset change value, the long downhill braking condition is released, and the condition is switched according to the change in the pedal depression position. Among them, Figure 5 The red line in the middle shows the oil circuit diagram under this working condition.

[0034] That is to say, when it is detected that the vehicle is in the boost braking condition for a long time and the pedal depressed position remains basically unchanged, in order to avoid the EV valve being energized for a long time and to improve system reliability, the long downhill braking condition will be activated. At this time, when the first proportional valve EV1 and the second proportional valve EV2 are adjusted to the planned control current, the first isolation valve ZLV1 is powered off and closed, the second isolation valve ZLV2 is powered on and closed, the first pressure relief valve AV1 and the second pressure relief valve AV2 remain closed for a long time, maintaining the pressure at the brake chuck to achieve long-distance downhill braking.

[0035] In a specific implementation process, when a large change in the pedal depression position is detected, it means that the working condition is different from the actual braking requirement of the vehicle. At this time, the long slope braking condition can be released and the working condition can be switched according to the change of the pedal. The specific working condition to be switched to can be switched according to the actual situation. For example, it can be switched to the boost braking condition on a flat road, the decompression braking condition on a flat road, etc., and examples will not be given one by one here.

[0036] In a specific implementation process, the operating condition includes a turning braking condition, and the turning braking condition includes a turning boost braking condition and a turning decompression braking condition; Under the turning braking condition, the pressure of the inner service brake cylinder and the pressure of the outer service brake cylinder are distributed according to the turning direction, so that the pressure of the outer service brake cylinder is greater than the pressure of the inner service brake cylinder; wherein, when the turning direction is left turn, the first service brake cylinder L is the inner service brake cylinder, and the second service brake cylinder R is the outer service brake cylinder; when the turning direction is right turn, the first service brake cylinder L is the outer service brake cylinder, and the second service brake cylinder R is the inner service brake cylinder.

[0037] Specifically, the pressure of the inner service brake cylinder and the pressure of the outer service brake cylinder can be distributed as follows: (1) Obtain the steering wheel angle, vehicle speed, road adhesion coefficient, vehicle center of mass height, wheelbase and track; The steering angle can be obtained by the steering wheel angle sensor, and the vehicle speed can be obtained by combining with the vehicle speed sensor. The road adhesion coefficient can be estimated based on the vehicle speed. The track width and wheelbase can be obtained from the vehicle structure.

[0038] (2) Based on the preset outer pressure distribution coefficient calculation formula, the outer pressure distribution coefficient is calculated using the steering angle, vehicle speed, road adhesion coefficient, vehicle center of mass height, wheelbase and wheelbase; The outside pressure distribution coefficient is calculated as follows:

[0039] in, represents the outer pressure distribution coefficient, Indicates the steering angle, Indicates the vehicle speed, represents the road adhesion coefficient, represents the reference road adhesion coefficient, Indicates the height of the vehicle's center of mass (the higher the center of mass, the greater the risk of rollover, and the greater the outer pressure compensation required). Indicates wheelbase (the distance between the left and right wheels. The wider the wheelbase, the weaker the load transfer and the better the stability). Indicates wheelbase (the distance between the front and rear axles, affecting the turning radius and lateral acceleration). represents the acceleration due to gravity, It represents the nonlinear correction index, which can be from 0.8 to 1.2. On slippery roads, the effect of μ on pressure distribution is nonlinear, and the risk of over-distribution needs to be weakened. represents the dynamic correction coefficient, Indicates the steering angular velocity (reflects the speed of steering, and requires rapid increase of outer pressure when turning sharply). Indicates longitudinal deceleration (when braking suddenly, the outer pressure needs to be increased to balance the inertia force).

[0040] It should be noted that constraints can be performed according to the following calculation formula:

[0041] That is to say, , making the pressure of the outer service brake cylinder greater than the pressure of the inner service brake cylinder.

[0042] (3) Based on the outer pressure distribution coefficient, the pressure of the inner service brake cylinder and the pressure of the outer service brake cylinder are determined.

[0043] In a specific implementation process, the pressure of the inner service brake cylinder and the pressure of the outer service brake cylinder can be obtained according to the following pressure distribution calculation formula:

[0044] in, Indicates the pressure of the outer service brake cylinder, Indicates the pressure of the inner service brake cylinder, Indicates the maximum pressure that can be provided. Indicates the brake signal percentage.

[0045] Figure 6 This is the principle diagram of the cornering boost braking condition, such as Figure 6As shown, under cornering boost braking conditions, the first isolation valve ZLV1 is energized and open, the second isolation valve ZLV2 is energized and closed, the first pressure relief valve AV1 and the second pressure relief valve AV2 are de-energized and remain closed, the balancing valve BV is energized and closed, the first proportional valve EV1 outputs a fourth adjustment ratio signal, the second proportional valve EV2 and the first proportional valve EV1 output a fifth adjustment ratio signal, so that the pressure of the first service brake cylinder L is different from the pressure of the second service brake cylinder R. Under this condition, the flow path of the oil circuit can be seen in Figure 6 The red line in.

[0046] That is to say, when the vehicle is in a cornering boost braking situation, the controller can distribute the braking pressure of the left and right wheels according to the turning direction, so that the braking pressure of the outer wheel is greater than that of the inner wheel, thereby fully utilizing the adhesion of the wheels. At this time, the first isolation valve ZLV1 is energized to open, the second isolation valve ZLV2 is energized to close, the first pressure relief valve AV1 and the second pressure relief valve AV2 are de-energized and remain closed, the balancing valve BV is energized to close to ensure that the left and right wheels can achieve different braking pressures, and the first proportional valve EV1 and the second proportional valve EV2 output a certain percentage of pressure according to the adjustment ratio signal given by the controller.

[0047] Figure 7 This is the principle diagram of the cornering decompression braking condition, such as Figure 7 As shown, under the cornering decompression braking condition, the first isolation valve ZLV1 is powered off and closed, the second isolation valve ZLV2 is powered on and closed, the balancing valve BV is powered on and closed, the first proportional valve EV1 outputs the sixth adjustment proportional signal, the second proportional valve EV2 outputs the seventh adjustment proportional signal, so that the pressure of the first service brake cylinder L is different from the pressure of the second service brake cylinder R, the first pressure relief valve AV1 and the second pressure relief valve AV2 are intermittently powered on and turned on, so that the pressure of the first service brake cylinder L meets the pressure corresponding to the sixth adjustment proportional signal, and the pressure of the second service brake cylinder R meets the pressure corresponding to the seventh adjustment proportional signal. Under this condition, the flow path of the oil circuit can be seen in Figure 7 The red line in.

[0048] That is to say, when the vehicle is in a turning decompression braking situation, it receives the decompression braking program from the controller, and the "service brake percentage instruction" begins to decrease (the service pressure signals of the two wheels are different at this time), the first isolation valve ZLV1 is powered off and closed, and the second isolation valve ZLV2 is powered on and closed, ensuring that the pressure in the brake cylinder does not increase. The balancing valve BV is powered on and closed, and the first pressure relief valve AV1 and the second pressure relief valve AV2 adjust the opening time through PWM to slowly reduce the pressure in the brake cylinder until the pressure specified by the "service brake percentage instruction" is met. At this time, the pressures in the left and right wheel brake cylinders are different, and the specific brake pressure = 10MPa*brake signal percentage%±0.5MPa.

[0049] like Figures 1 to 7 As shown, the vehicle multi-mode hydraulic brake system may further include a second pressure sensor PU2 and a third pressure sensor PU3. The second pressure sensor PU2 is used to detect the pressure of the first service brake cylinder L, and the third pressure sensor PU3 is used to detect the pressure of the second service brake cylinder R.

[0050] In a specific implementation process, the working condition includes a continuous braking automatic decompression working condition; under this working condition, if the pressure of the first service brake cylinder L is greater than the required pressure of the first service brake cylinder L, and / or the pressure of the second service brake cylinder R is greater than the required pressure of the second service brake cylinder R, automatic decompression is performed; wherein, the first isolation valve ZLV1 is powered off and closed, the second isolation valve ZLV2 is powered on and closed, the first pressure relief valve AV1 and the second pressure relief valve AV2 are intermittently powered on and connected, and the balancing valve BV maintains the state before automatic decompression.

[0051] That is to say, when the vehicle is continuously braked, the oil temperature in the first service brake cylinder L and / or the second service brake cylinder R will increase, thereby causing the system pressure to increase. When it is detected that the pressure of the first service brake cylinder L is higher than the required value range given by the controller to the first proportional valve EV1, and / or the pressure of the second service brake cylinder R is higher than the required value range given by the controller to the second proportional valve EV2, the automatic decompression condition is started, and the first pressure relief valve AV1 and the second pressure relief valve AV2 are controlled by PWM waves to reduce the system pressure to the required pressure. At this time, the first proportional valve EV1 and the second proportional valve EV2 are in a stopped pressurization state, the first isolation valve ZLV1 is powered off and closed, and the second isolation valve ZLV2 is powered on and closed, and the state of the balancing valve BV remains the same as before decompression.

[0052] In a specific implementation, the braking process may also include an accumulator pressure insufficient braking condition. In this condition, when the vehicle is in a braking state and the accumulator pressure drops below 12MPa due to braking, the condition is activated. At this time, the motor is energized, the ZLV1 valve is energized to open, and the ZLV2 valve is energized to close. While the vehicle is braking, the motor is started to replenish the accumulator to the maximum extent possible to ensure subsequent braking pressure. Figure 8 , Figure 8 This is the principle diagram of the braking condition when the accumulator pressure is insufficient. In this condition, the oil flow path can be seen in Figure 8 The red line in.

[0053] In a specific implementation process, the working condition includes a pressure maintaining working condition. Figure 9 This is the principle diagram of the pressure maintaining working condition corresponding to the first service brake cylinder L, that is, the left wheel pressure maintaining working condition, such as Figure 9 As shown, in the left wheel pressure-maintaining condition, if the pressure of the first service brake cylinder L is greater than the fourth preset pressure and less than the required pressure of the first service brake cylinder L, the first isolation valve ZLV1 is energized and turned on, the second isolation valve ZLV2 is energized and closed, the balancing valve BV is energized and closed, the first proportional valve EV1 is energized and closed, and the second proportional valve EV2 maintains its original state to maintain the pressure of the first service brake cylinder L. In this condition, the flow path of the oil circuit can be seen in Figure 9 The red line in the figure shows the oil flow when the second service brake cylinder R is releasing pressure. Figure 9 The blue line in.

[0054] That is to say, when it is detected that the pressure value of the vehicle's left wheel is too high and the wheel may lock, the left wheel pressure maintaining condition is activated. At this time, the second isolation valve ZLV2 is energized to close, and the first isolation valve ZLV1 is energized to open. The balance is energized to close to make the pressure of the left and right wheels different, and the first proportional valve EV1 stops increasing the pressure to the left wheel. The second proportional valve EV2 outputs a certain percentage of pressure according to the adjustment proportion signal given by the controller to maintain the pressure and braking status of the left and right wheels respectively, and the other valves remain normal.

[0055] Figure 10 This is the principle diagram of the pressure maintaining working condition corresponding to the second service brake cylinder R, that is, the right wheel pressure maintaining working condition, such as Figure 10 As shown, if the pressure of the second service brake cylinder R is greater than the fourth preset pressure and less than the required pressure of the second service brake cylinder R, the first isolation valve ZLV1 is controlled to be energized and open, the second isolation valve ZLV2 is energized and closed, the balancing valve BV is energized and closed, the second proportional valve EV2 is energized and closed, and the first proportional valve EV1 maintains its original state to maintain the pressure of the second service brake cylinder R. In this working condition, the flow path of the oil circuit can be seen in Figure 10The red line in the figure shows the oil flow when the second service brake cylinder R is releasing pressure. Figure 10 The blue line in.

[0056] That is to say, when it is detected that the pressure value of the right wheel of the vehicle is too high and the wheel may lock, the right wheel pressure maintaining condition is activated. At this time, the second isolation valve ZLV2 is energized to close, and the first isolation valve ZLV1 is energized to open. The balance is energized to close to make the pressure of the left and right wheels different, and the second proportional valve EV2 stops increasing the pressure to the right wheel. The first proportional valve EV1 outputs a certain percentage of pressure according to the adjustment proportion signal given by the controller to maintain the pressure and braking status of the left and right wheels respectively, and the other valves remain normal.

[0057] In a specific implementation process, the working condition includes a pressure-maintaining followed by a pressure-reducing working condition. Figure 11 This is the principle diagram of the decompression working condition corresponding to the first service brake cylinder L, that is, the decompression working condition after the left wheel maintains pressure, such as Figure 11 As shown, under the left wheel pressure-maintaining and then pressure-reducing operating condition, if the pressure of the first service brake cylinder L is greater than the fifth preset pressure and less than the fourth preset pressure after the first service brake cylinder L enters the pressure-maintaining operating condition for the second preset time, the first isolation valve ZLV1 is controlled to be energized and open, the second isolation valve ZLV2 is energized and closed, the balancing valve BV is energized and closed, the first proportional valve EV1 is energized and closed, the second proportional valve EV2 maintains its original state, and the first pressure relief valve AV1 is intermittently energized and opened to relieve the pressure of the first service brake cylinder L. Under this operating condition, the flow path of the oil circuit can be seen in Figure 11 The red line in the figure shows the oil flow when the second service brake cylinder R is releasing pressure. Figure 11 The green line in .

[0058] That is to say, when the brake pressure is still too high after the left wheel of the vehicle enters the pressure maintaining state, the left wheel decompression condition is entered. At this time, the balance power is turned off, the first proportional valve EV1 stops increasing pressure to the left wheel, and the first pressure relief valve AV1 is opened intermittently to reduce the brake pressure to meet the requirements.

[0059] Figure 12 This is the principle diagram of the decompression working condition corresponding to the second service brake cylinder R, that is, the decompression working condition after the right wheel maintains pressure, such as Figure 12 As shown, if the pressure of the second service brake cylinder R is greater than the fifth preset pressure and less than the fourth preset pressure after the first service brake cylinder L enters the pressure holding condition for the second preset time, the first isolation valve ZLV1 is controlled to be energized and open, the second isolation valve ZLV2 is energized and closed, the balancing valve BV is energized and closed, the second proportional valve EV2 is energized and closed, the first proportional valve EV1 maintains its original state, and the second pressure relief valve AV2 is intermittently energized and opened to relieve the pressure of the second service brake cylinder R. Under this condition, the flow path of the oil circuit can be seen in Figure 12The red line in the figure shows the oil flow when the second service brake cylinder R is releasing pressure. Figure 12 The green line in .

[0060] That is to say, when the brake pressure of the right wheel of the vehicle is still too high after entering the ABS pressure holding state, the right wheel decompression condition is entered. At this time, the balance power is turned off, the second proportional valve EV2 stops increasing pressure to the right wheel, and the first pressure relief valve AV1 is opened intermittently to reduce the brake pressure to meet the requirements.

[0061] In a specific implementation process, the power supply conditions of each valve corresponding to each of the above working conditions can be specifically referred to Table 1: Table 1 shows the power supply conditions of each valve corresponding to each working condition

[0062] The vehicle multi-mode hydraulic braking system of this embodiment is configured with a normally open second isolation valve ZLV2 between the outlet side of the first isolation valve ZLV1 and the fluid reservoir C. In this way, when the braking subsystem is not braking, the oil leaked from the outlet of the first isolation valve ZLV1 flows back to the fluid reservoir C through the second isolation valve ZLV2, thereby preventing the oil leaked from the outlet of the first isolation valve ZLV1 from flowing into the braking subsystem, avoiding the brake caliper in the braking subsystem from continuously acting on the brake disc, and generating no drag torque, thereby reducing wear on the brake cylinder, resulting in less vehicle driving resistance, reduced vehicle fuel consumption, improved power performance, and improved response accuracy of the braking subsystem, thereby improving vehicle driving safety.

[0063] In a specific implementation process, the vehicle multi-mode hydraulic brake system can also perform vehicle startup inspection and vehicle inspection while driving.

[0064] Specifically, the vehicle startup inspection includes the following aspects: 1) Confirm the status of the accumulator ACC: Check the pressure value of the accumulator ACC. If the pressure value of the accumulator ACC is lower than 12 MPa, start the motor M of the hydraulic subsystem to drive the hydraulic pump PUMP to fill the accumulator ACC to a pressure of 14 MPa and then stop; 2) Under normal circumstances, the hydraulic pump PUMP will not take more than 15 seconds to fill the accumulator ACC. In the case of "no service brake command percentage", if the continuous filling time exceeds 30 seconds after the motor M pump group is started, and the accumulator ACC pressure detection value is still ≤14MPa, the brake system alarm will be issued, indicating "hydraulic system or brake oil circuit abnormality", and the vehicle needs to be stopped for inspection; 3) Check whether the working status of the first pressure sensor PU1 to the third pressure sensor PU3 is normal. If the pressure signal is normal, the switch value is "1", and if the pressure signal is abnormal, the switch value is "0". As long as the pressure signal output of the accumulator ACC is abnormal, the controller outputs the switch value "0"; as long as one of the pressure sensors corresponding to the service brake cylinder is abnormal, the controller outputs the switch value "0".

[0065] Vehicle inspections while driving may include the following aspects: 1) When there is a "service brake percentage instruction", the detection value of the service brake pressure sensor (the second pressure sensor PU2 and / or the third pressure sensor PU3) should be within the range of "10MPa×service brake percentage%"±1MPa. If the detection value of the service brake pressure sensor is outside the range of "10MPa×service brake percentage%"±1MPa, the vehicle's multi-condition hydraulic brake system alarm will be triggered, indicating "abnormal service brake cylinder boost pressure".

[0066] 2) There is no "service brake percentage instruction or the service percentage is 0", the service brake pressure sensor value should be ≤0.1MPa. If the service brake pressure sensor value is greater than 0.1MPa, the vehicle's multi-condition hydraulic brake system alarm indicates "abnormal service brake cylinder decompression".

[0067] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A vehicle multi-mode hydraulic braking system, characterized in that: Including controller, hydraulic subsystem, oil control subsystem and brake subsystem; The hydraulic subsystem includes a motor, a fluid storage tank, a hydraulic pump, a relief valve, a one-way valve, an accumulator, a first pressure sensor, a first isolation valve and a second isolation valve; The motor is electrically connected to the hydraulic pump and the controller; The inlet of the hydraulic pump and the outlet of the relief valve are in communication with the liquid storage tank, and the outlet of the hydraulic pump is in communication with the inlet of the one-way valve and the inlet of the relief valve; The outlet of the one-way valve and the inlet of the first isolation valve are in communication with the accumulator; the first pressure sensor is used to detect the pressure of the accumulator; The outlet of the first isolation valve is in communication with the oil control subsystem and the inlet of the second isolation valve; The oil control subsystem is in communication with the brake subsystem; The outlet of the second isolation valve is connected to the fluid storage tank; wherein, the second isolation valve is configured to be in a normally open state, so that when the braking subsystem is not braking, the oil leaked from the outlet of the first isolation valve flows back to the fluid storage tank through the second isolation valve.

2. The vehicle multi-mode hydraulic brake system according to claim 1, characterized in that: The oil control subsystem includes a first proportional valve, a second proportional valve, a first pressure relief valve, a second pressure relief valve and a balance valve; the brake subsystem includes a first service brake cylinder and a second service brake cylinder; The outlet of the first proportional valve is in communication with the inlet of the first pressure relief valve, the first opening of the balancing valve, and the first service brake cylinder; The outlet of the second proportional valve is in communication with the inlet of the second pressure relief valve, the second opening of the balancing valve and the second service brake cylinder; The outlet of the first pressure relief valve and the outlet of the second pressure relief valve are in communication with the liquid storage tank; The controller is configured to control the braking or non-braking of the braking subsystem by controlling the working state of the target valve and the motor according to different working conditions; wherein the target valve includes at least one of the first isolation valve, the second isolation valve, the first proportional valve, the second proportional valve, the first pressure relief valve, the second pressure relief valve and the balancing valve.

3. The vehicle multi-mode hydraulic brake system according to claim 2, characterized in that: The operating conditions include accumulator refilling conditions; When the pressure value detected by the first pressure sensor is less than a first preset pressure value, the motor is started, so that the motor drives the hydraulic pump to replenish the accumulator, until the pressure value detected by the first pressure sensor is greater than a second preset pressure value, and the motor is controlled to stop running; The first isolation valve, the second isolation valve, the first proportional valve, the second proportional valve, the first pressure relief valve, the second pressure relief valve and the balancing valve are all de-energized.

4. The vehicle multi-mode hydraulic brake system according to claim 2, characterized in that: The operating conditions include unbraked driving conditions; When there is no service brake percentage instruction, the first isolation valve, the second isolation valve, the first proportional valve, the second proportional valve, the first pressure relief valve, the second pressure relief valve and the balancing valve are all de-energized, and the motor determines whether to work based on the pressure of the accumulator. The first proportional valve and the second proportional valve both output a first adjustment proportional signal that is less than a preset proportion, so that the pressure of the first service brake cylinder and the pressure of the second service brake cylinder are both less than or equal to a third preset pressure.

5. The vehicle multi-mode hydraulic brake system according to claim 2, characterized in that: The operating conditions include a boost braking condition on a straight road and a decompression braking condition on a straight road; Under the boost braking condition on a straight road, the first isolation valve is energized and opened, the second isolation valve is energized and closed, the first and second proportional valves output second adjustment proportional signals, and the balancing valve is de-energized and remains open, so that the pressure of the first service brake cylinder and the pressure of the second service brake cylinder both meet the pressure corresponding to the second adjustment proportional signal; Under the straight road pressure reduction braking condition, the first isolation valve is powered off and closed, the second isolation valve is powered on and closed, the first proportional valve and the second proportional valve output a third adjustment proportional signal, the balancing valve is de-energized and remains conductive, the first pressure relief valve and the second pressure relief valve are intermittently powered on and conductive, so that the pressure of the first service brake cylinder and the pressure of the second service brake cylinder both meet the pressure corresponding to the third adjustment proportional signal; wherein, the pressure corresponding to the third adjustment proportional signal is less than the pressure corresponding to the second adjustment proportional signal.

6. The vehicle multi-mode hydraulic brake system according to claim 2, characterized in that: The operating conditions include long downhill braking conditions; When it is detected that the vehicle performs boost braking for a duration greater than a first preset duration and the change in the pedal depression position is less than a preset change value, the first proportional valve and the second proportional valve are adjusted to a set control current, the first isolation valve is de-energized and closed, the second isolation valve is energized and closed, and the first pressure relief valve and the second pressure relief valve are de-energized and remain closed; When it is detected that the change value of the pedal depressed position is greater than the preset change value, the long downhill braking condition is released and the condition is switched according to the change value of the pedal depressed position.

7. The vehicle multi-mode hydraulic brake system according to claim 2, characterized in that: The operating conditions include turning braking conditions, which include turning pressure-boosting braking conditions and turning pressure-reducing braking conditions; In the turning braking condition, the pressure of the inner service brake cylinder and the pressure of the outer service brake cylinder are distributed according to the turning direction, so that the pressure of the outer service brake cylinder is greater than the pressure of the inner service brake cylinder; wherein, when the turning direction is left, the first service brake cylinder is the inner service brake cylinder and the second service brake cylinder is the outer service brake cylinder; when the turning direction is right, the first service brake cylinder is the outer service brake cylinder and the second service brake cylinder is the inner service brake cylinder; In a cornering boost braking condition, the first isolation valve is energized and turned on, the second isolation valve is energized and closed, the first pressure relief valve and the second pressure relief valve are de-energized and remain closed, the balancing valve is energized and closed, the first proportional valve outputs a fourth adjustment proportional signal, and the second proportional valve and the first proportional valve output a fifth adjustment proportional signal, so that the pressure of the first service brake cylinder is different from the pressure of the second service brake cylinder; Under the cornering decompression braking condition, the first isolation valve is powered off and closed, the second isolation valve is powered on and closed, the balancing valve is powered on and closed, the first proportional valve outputs the sixth adjustment proportional signal, and the second proportional valve outputs the seventh adjustment proportional signal, so that the pressure of the first service brake cylinder is different from the pressure of the second service brake cylinder, and the first pressure relief valve and the second pressure relief valve are intermittently powered on and turned on, so that the pressure of the first service brake cylinder meets the pressure corresponding to the sixth adjustment proportional signal, and the pressure of the second service brake cylinder meets the pressure corresponding to the seventh adjustment proportional signal.

8. The vehicle multi-mode hydraulic brake system according to claim 2, characterized in that: Also included is a second pressure sensor and a third pressure sensor; The second pressure sensor is used to detect the pressure of the first service brake cylinder, and the third pressure sensor is used to detect the pressure of the second service brake cylinder; The operating conditions include a continuous braking automatic decompression operating condition; If the pressure of the first service brake cylinder is greater than the required pressure of the first service brake cylinder, and / or the pressure of the second service brake cylinder is greater than the required pressure of the second service brake cylinder, automatically reducing pressure; The first isolation valve is powered off and closed, the second isolation valve is powered on and closed, the first pressure relief valve and the second pressure relief valve are intermittently powered on and connected, and the balancing valve maintains the state before automatic decompression.

9. The vehicle multi-mode hydraulic brake system according to claim 8, characterized in that: The working conditions include pressure maintaining working conditions; Under the pressure maintaining condition, if the pressure of the first service brake cylinder is greater than the fourth preset pressure and less than the required pressure of the first service brake cylinder, the first isolation valve is controlled to be energized and turned on, the second isolation valve is energized and closed, the balancing valve is energized and closed, the first proportional valve is energized and closed, and the second proportional valve maintains its original state to maintain the pressure of the first service brake cylinder; if the pressure of the second service brake cylinder is greater than the fourth preset pressure and less than the required pressure of the second service brake cylinder, the first isolation valve is controlled to be energized and turned on, the second isolation valve is energized and closed, the balancing valve is energized and closed, the second proportional valve is energized and closed, and the first proportional valve maintains its original state to maintain the pressure of the second service brake cylinder.

10. The vehicle multi-mode hydraulic brake system according to claim 9, characterized in that: The working condition includes a pressure-maintaining followed by a pressure-reducing working condition; Under the pressure-maintaining and pressure-reducing working condition, if the pressure of the first service brake cylinder is greater than the fifth preset pressure and less than the fourth preset pressure after the first service brake cylinder enters the pressure-maintaining working condition for the second preset time, the first isolation valve is controlled to be energized and turned on, the second isolation valve is energized and closed, the balancing valve is energized and closed, the first proportional valve is energized and closed, the second proportional valve maintains its original state, and the first pressure relief valve is intermittently energized and turned on to relieve the pressure of the first service brake cylinder; if the pressure of the second service brake cylinder is greater than the fifth preset pressure and less than the fourth preset pressure after the first service brake cylinder enters the pressure-maintaining working condition for the second preset time, the first isolation valve is controlled to be energized and turned on, the second isolation valve is energized and closed, the balancing valve is energized and closed, the second proportional valve is energized and closed, the first proportional valve maintains its original state, and the second pressure relief valve is intermittently energized and turned on to relieve the pressure of the second service brake cylinder.

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