High precision electro-hydraulic brake system

Abstract

The application relates to the field of vehicle electro-hydraulic braking, in particular to a high-precision electro-hydraulic braking system which comprises an oil tank, an energy storage unit, a braking execution end and a hydraulic control unit, the oil tank is used for storing brake fluid; the energy storage unit is used for building pressure for the brake fluid; the braking execution end realizes braking action through brake fluid pressure building and pressure releasing; the hydraulic control unit is used for connecting the energy storage unit and the corresponding braking execution end, the hydraulic control unit comprises a first normally open valve, a second normally open valve and a first normally closed valve, one end of the first normally open valve is connected with the energy storage unit, and the other end is connected with the braking execution end; one end of the second normally open valve is connected with the other end of the first normally open valve; one end of the first normally closed valve is connected with the other end of the second normally open valve, and the other end of the first normally closed valve is connected with the oil tank. The pressure releasing process of the braking execution end can be accurately adjusted, the influence caused by the poor consistency of electromagnetic valves can be effectively offset, the wheel edge pressure releasing error can be controlled in a low range, and the high-precision braking demand can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle electro-hydraulic braking, in particular to a high-precision electro-hydraulic braking system. BACKGROUND

[0002] In the field of vehicle electro-hydraulic braking system, the core function is to realize the pressure building, pressure maintaining and pressure releasing of the wheel edge braking execution end through hydraulic control to meet the braking demand of the vehicle. In the prior art, the mainstream pressure releasing control design adopts the structure of "single loop + single normally closed electromagnetic valve", that is, each wheel edge pressure releasing loop is only configured with one normally closed electromagnetic valve, and the pressure releasing operation is realized through the on-off of the electromagnetic valve.

[0003] Although this design can meet the scene with low requirements on pressure releasing precision and response speed, it has obvious defects in the scene with high-precision braking demand. On the one hand, the single normally closed electromagnetic valve action has inherent delay and cannot quickly respond to the wheel edge precise pressure releasing demand, especially in emergency braking, which may affect the braking safety. On the other hand, the consistency of the electromagnetic valve itself is quite different, and the on-off performance and flow control of different electromagnetic valves have deviations, which are difficult to eliminate through software compensation, resulting in insufficient pressure releasing precision. In addition, if the target pressure closed-loop control is used to improve the precision, the on-off adjustment of the single electromagnetic valve is easy to cause the frequent fluctuation of the wheel edge pressure, which affects the driving experience.

[0004] To solve the above problems, the present application provides a high-precision electro-hydraulic braking system, which optimizes the structure of the hydraulic control unit and the connection relationship of each component to effectively improve the pressure releasing control precision and response speed and make up for the deficiencies of the prior art. SUMMARY

[0005] The present application provides a high-precision electro-hydraulic braking system to solve the problems of low wheel edge pressure releasing control precision and obvious wheel edge pressure fluctuation effect in the prior art.

[0006] The present application provides a high-precision electro-hydraulic braking system, which comprises:

[0007] An oil tank for storing brake fluid;

[0008] An energy storage unit for building pressure for the brake fluid;

[0009] A brake execution end for realizing braking action through brake fluid pressure building / releasing;

[0010] A hydraulic control unit for connecting the energy storage unit and the corresponding brake execution end, the hydraulic control unit comprising:

[0011] A first normally open valve, one end of the first normally open valve being connected with the energy storage unit and the other end being connected with the brake execution end;

[0012] The second normally open valve has one end connected to the other end of the first normally open valve.

[0013] The first normally closed valve has one end connected to the other end of the second normally open valve, and the other end of the first normally closed valve is connected to the oil tank.

[0014] In one possible design, the hydraulic control unit also includes:

[0015] The third normally open valve has one end connected to the energy storage unit and the other end connected to the braking actuator.

[0016] The fourth normally open valve has one end connected to the other end of the third normally open valve;

[0017] The second normally closed valve has one end connected to the other end of the fourth normally open valve, and the other end of the second normally closed valve is connected to the oil tank.

[0018] In one possible design, the brake actuator includes a first caliper and a second caliper, with a fifth normally open valve disposed between the first caliper and the second caliper. One end of the fifth normally open valve is connected to the oil circuit of the first caliper, and the other end is connected to the oil circuit of the second caliper.

[0019] In one possible design, a first pressure sensor and a second pressure sensor are also included, the first pressure sensor being used to acquire the oil pressure in the oil circuit of the first caliper, and the second pressure sensor being used to acquire the oil pressure in the oil circuit of the second caliper.

[0020] In one possible design, a third normally closed valve is also included, one end of which is connected to the other end of the first normally closed valve and the other end of the second normally closed valve, and the other end of the third normally closed valve is connected to the oil tank.

[0021] In one possible design, a two-position three-way valve is also included. The two-position three-way valve has a first interface, a second interface, and a third interface. The first interface is connected to the energy storage unit, the second interface is connected to one end of the first normally open valve and one end of the third normally open valve, and the third interface is connected to one end of the third normally closed valve.

[0022] In one possible design, a sixth normally open valve is also included. The sixth normally open valve is connected in parallel with a two-position three-way valve. One end of the sixth normally open valve is connected to the energy storage unit, and the other end is connected to one end of the first normally open valve and one end of the third normally open valve, respectively.

[0023] In one possible design, the first normally open valve, the second normally open valve, the third normally open valve, and the fourth normally open valve are all connected in parallel with the first check valve.

[0024] In one possible design, the energy storage unit includes:

[0025] An accumulator is used to store brake fluid pressure. A third pressure sensor is installed in the accumulator's oil circuit to collect the accumulator's pressure.

[0026] The pump assembly is connected to the oil tank at one end and to the accumulator at the other end. The pump assembly is also connected to an overflow valve.

[0027] The second check valve is located between the pump assembly and the accumulator, with one end connected to the pump assembly and the other end connected to the accumulator, and is used to prevent brake fluid backflow.

[0028] In one possible design, a level sensor is installed inside the fuel tank to collect the level of brake fluid in the tank.

[0029] The beneficial effects of this application are as follows:

[0030] This high-precision electro-hydraulic braking system, through a combination design of a normally open valve and a normally closed valve, can precisely regulate the pressure relief process at the end of the braking action, effectively offsetting the impact of inconsistencies in the solenoid valves, and controlling the wheel-side pressure relief error within a low range to meet high-precision braking requirements. Compared to existing single normally closed solenoid valve pressure relief designs, this system features multiple valves working in tandem, enabling rapid switching of the hydraulic circuit state and pre-emptive preparation for pressure relief, significantly shortening the pressure relief response time. This is especially beneficial in emergency braking scenarios, enhancing braking safety.

[0031] By using a combined control method of "coarse adjustment with normally open valve + fine adjustment with normally closed valve" to replace the traditional target pressure closed-loop control, the problem of wheel-side pressure oscillation caused by single solenoid valve adjustment is effectively avoided, improving the driving experience. At the same time, it reduces the reliance on complex software compensation logic and reduces the risk of system failure.

[0032] When the system experiences an abnormal power failure, the emergency braking function of the sixth normally open valve and the pressure protection function of the relief valve further enhance the safety and reliability of the system under various operating conditions, ensuring stable vehicle braking performance. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 The schematic diagram of the high-precision electro-hydraulic braking system provided in the embodiments of this application is shown.

[0035] Figure label:

[0036] 1. Liquid level sensor; 2. Pump assembly; 3. Second check valve; 4. Accumulator; 5. Third pressure sensor; 6. Sixth normally open valve; 7. Two-position three-way valve; 8. First normally open valve; 9. Second normally open valve; 10. First normally closed valve; 11. First pressure sensor; 12. First caliper; 13. Fifth normally open valve; 14. Second caliper; 15. Second pressure sensor; 16. Second normally closed valve; 17. Fourth normally open valve; 18. Third normally open valve; 19. Third normally closed valve; 20. Relief valve; 21. Oil tank. Detailed Implementation

[0037] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] The following is combined Figure 1 This application describes a high-precision electro-hydraulic braking system provided in the embodiments of this application.

[0039] The high-precision electro-hydraulic braking system of this application embodiment includes an oil tank 21, an energy storage unit, a braking actuator, and a hydraulic control unit.

[0040] The oil tank 21 serves as a storage container for brake fluid, providing a stable fluid source for the entire electro-hydraulic braking system. An internal level sensor 1 is installed in the oil tank 21, which collects real-time brake fluid level information. When the level sensor 1 detects that the brake fluid level is below a preset lower limit, it will promptly issue an alarm signal, reminding personnel to replenish the brake fluid. This prevents a decrease in system braking performance due to insufficient brake fluid, ensuring the safety and reliability of system operation.

[0041] The core function of the energy storage unit is to build up and store pressure for the brake fluid, ensuring a stable pressure supply during braking. Specifically, it includes an accumulator 4, a pump assembly 2, a second check valve 3, and a relief valve 20.

[0042] Accumulator 4 is mainly used to store brake fluid pressure, providing pressure support for pressure build-up at the end of braking. A third pressure sensor 5 is installed in the oil circuit of accumulator 4, which can collect brake fluid pressure data in accumulator 4 in real time. When the pressure of accumulator 4 is detected to be lower than the preset lower pressure limit of the system, a pressure replenishment program is triggered; when the pressure is higher than the preset upper pressure limit, the pressure replenishment program stops, ensuring that accumulator 4 is always within a stable pressure range, thus guaranteeing the pressure supply to the system.

[0043] One end of the pump assembly 2 is connected to the oil tank 21, and the other end is connected to the accumulator 4, serving as the power source for pressurizing the brake fluid. After the pump assembly 2 is started, it can draw brake fluid from the oil tank 21, pressurize it, and then deliver the pressurized brake fluid to the accumulator 4 for storage.

[0044] The second check valve 3 is located between the pump assembly 2 and the accumulator 4, with one end connected to the pump assembly 2 and the other end connected to the accumulator 4. The main function of the second check valve 3 is to prevent brake fluid backflow, avoid the pressurized brake fluid from impacting the pump assembly 2 in the reverse direction, protect the normal operation of the pump assembly 2, and ensure that the pressure in the accumulator 4 is not lost due to brake fluid backflow.

[0045] The overflow valve 20 is connected to the pump assembly 2. When the pressure in the system exceeds the preset upper limit, the overflow valve 20 will automatically open to return the excess brake fluid to the oil tank 21, thereby preventing the system pressure from being too high and damaging the components, and ensuring that the system pressure is stable within a safe range.

[0046] The brake actuator is a key component for realizing vehicle braking, and it completes the braking operation by building up and releasing brake fluid pressure. In this embodiment, the brake actuator includes a first caliper 12 and a second caliper 14, which correspond to different wheels of the vehicle (such as the left front wheel and the right front wheel, the left rear wheel and the right rear wheel, etc.). By receiving pressurized brake fluid from the hydraulic control unit or releasing brake fluid, it realizes the braking and release of the wheels.

[0047] To accurately monitor the oil pressure in the hydraulic circuits of the first caliper 12 and the second caliper 14, the system is also equipped with a first pressure sensor 11 and a second pressure sensor 15. The first pressure sensor 11 collects the oil pressure in the first caliper 12 circuit, and the second pressure sensor 15 collects the oil pressure in the second caliper 14 circuit. Through the real-time oil pressure data fed back by these two pressure sensors, the system can accurately grasp the pressure state at the end of the braking actuator, providing a basis for the precise control of the hydraulic control unit and ensuring the stability and accuracy of the braking action.

[0048] In some embodiments, a fifth normally open valve 13 is provided between the first caliper 12 and the second caliper 14. One end of the fifth normally open valve 13 is connected to the oil circuit of the first caliper 12, and the other end is connected to the oil circuit of the second caliper 14. When the first caliper 12 and the second caliper 14 require brake fluid of the same pressure for braking, the fifth normally open valve 13 is in the conducting state, connecting the oil circuits of the two calipers and ensuring that the pressures are consistent. When the two calipers require different pressures, the fifth normally open valve 13 is in the closed state. At this time, the precise supply of different pressures can be achieved by adjusting the hydraulic control branches corresponding to the two calipers respectively, so as to meet the braking needs of the vehicle under different operating conditions.

[0049] The hydraulic control unit connects the energy storage unit to the brake actuator, controlling the flow direction and volume of brake fluid to achieve pressure build-up, pressure holding, and pressure release at the brake actuator. The hydraulic control unit specifically includes multiple sets of valves, which work together to meet the control requirements of different braking scenarios.

[0050] In this embodiment, the hydraulic control unit for the first caliper 12 is equipped with a first normally open valve 8, a second normally open valve 9, and a first normally closed valve 10. One end of the first normally open valve 8 is connected to the energy storage unit, and the other end is connected to the first caliper 12. One end of the second normally open valve 9 is connected to the other end of the first normally open valve 8 (the end closer to the first caliper 12). One end of the first normally closed valve 10 is connected to the other end of the second normally open valve 9, and the other end is connected to the oil tank 21. During braking, by controlling the opening of the first normally open valve 8 and the second normally open valve 9 and the closing of the first normally closed valve 10, brake fluid can be delivered to the first caliper 12 to build up pressure. When pressure relief is required, the first normally open valve 8 is closed, and the second normally open valve 9 and the first normally closed valve 10 are connected, allowing the brake fluid in the first caliper 12 to flow back to the oil tank 21 via the second normally open valve 9 and the first normally closed valve 10, thus relieving pressure.

[0051] Corresponding to the second caliper 14, the hydraulic control unit is equipped with a third normally open valve 18, a fourth normally open valve 17, and a second normally closed valve 16. One end of the third normally open valve 18 is connected to the energy storage unit, and the other end is connected to the second caliper 14; one end of the fourth normally open valve 17 is connected to the other end of the third normally open valve 18 (the end closer to the second caliper 14); one end of the second normally closed valve 16 is connected to the other end of the fourth normally open valve 17, and the other end is connected to the oil tank 21. Its working principle is similar to that of the valve group corresponding to the first caliper 12. By controlling the opening of the third normally open valve 18 and the fourth normally open valve 17 and the closing of the second normally closed valve 16, pressure is built up in the second caliper 14; by controlling the closing of the third normally open valve 18 and the opening of the fourth normally open valve 17 and the second normally closed valve 16, pressure is released from the second caliper 14.

[0052] To prevent brake fluid from flowing backward and to ensure stable oil circuit pressure, the first normally open valve 8, the second normally open valve 9, the third normally open valve 18, and the fourth normally open valve 17 are all connected in parallel with a first check valve. These first check valves only allow brake fluid to flow from the accumulator unit towards the end of the braking process, preventing brake fluid backflow due to pressure fluctuations during braking, which would affect braking performance and system stability.

[0053] In some embodiments, the system further includes a third normally closed valve 19, one end of which is connected to the other end of the first normally closed valve 10 and the other end of the second normally closed valve 16, and the other end of the third normally closed valve 19 is connected to the oil tank 21. During normal pressure relief, the third normally closed valve 19 is in the open state, providing a channel for the brake fluid flowing out of the first normally closed valve 10 and the second normally closed valve 16 to flow back to the oil tank 21; when the system malfunctions, such as when emergency pressure maintenance is required, the third normally closed valve 19 can be shut off to block the brake fluid backflow, cooperating with other valves to ensure stable system pressure and improve system safety.

[0054] In some embodiments, the system further includes a two-position three-way valve 7 and a sixth normally open valve 6.

[0055] Specifically, the two-position three-way valve 7 has a first port, a second port, and a third port. The first port is connected to the energy storage unit, the second port is connected to one end of the first normally open valve 8 and one end of the third normally open valve 18, and the third port is connected to one end of the third normally closed valve 19. The two-position three-way valve 7 is mainly used to switch the flow direction of the brake fluid. When the system needs to build pressure at the end of the braking action, the two-position three-way valve 7 controls the first port and the second port to be connected, so that the pressurized brake fluid in the energy storage unit is delivered to the first normally open valve 8 and the third normally open valve 18 through the second port. When a specific pressure relief operation is required, the second port and the third port can be connected to flexibly adjust the oil circuit connection status.

[0056] The sixth normally open valve 6 is connected in parallel with the two-position three-way valve 7. One end of the valve is connected to the energy storage unit, and the other end is connected to one end of the first normally open valve 8 and one end of the third normally open valve 18, respectively. The sixth normally open valve 6 is mainly used in emergency situations such as abnormal power failure of the system. When the abnormal power failure of the system causes the two-position three-way valve 7 to malfunction, the sixth normally open valve 6 is opened, so that the brake fluid in the energy storage unit can be directly delivered to the first normally open valve 8 and the third normally open valve 18, and then flow to the end of the brake actuator to realize emergency braking and ensure the braking safety of the vehicle in abnormal situations.

[0057] The braking principle and working process of the high-precision electro-hydraulic braking system described in this application are as follows:

[0058] 1. Standby and pressure compensation process:

[0059] When the system is in standby mode, pump assembly 2 is not started, and the pressure in accumulator 4 remains within the normal range. The third pressure sensor 5 monitors the pressure in accumulator 4 in real time. When the pressure falls below a preset lower limit, pump assembly 2 is triggered to start. Pump assembly 2 draws brake fluid from tank 21 and pressurizes it. The pressurized brake fluid is then delivered to accumulator 4 via the second one-way valve 3. When the third pressure sensor 5 detects that the pressure in accumulator 4 has reached a preset upper limit, pump assembly 2 stops working, and the system returns to standby mode, awaiting braking commands.

[0060] 2. Pressure build-up process:

[0061] Universal pressure build-up (first caliper 12 and second caliper 14 require the same pressure): Two-position three-way valve 7 controls the connection between the first and second interfaces, while the sixth normally open valve 6 is closed. First normally open valve 8 and third normally open valve 18 are open, second normally open valve 9 and fourth normally open valve 17 are open, first normally closed valve 10 and second normally closed valve 16 are closed, and fifth normally open valve 13 is open. The pressurized brake fluid in accumulator 4 flows to the first caliper 12 via the second interface of two-position three-way valve 7, first normally open valve 8, and second normally open valve 9, and simultaneously flows to the second caliper 14 via third normally open valve 18 and fourth normally open valve 17. Because the fifth normally open valve 13 is open, the oil circuits of the two calipers are connected, the pressure is consistent, pressure build-up is completed, and braking is achieved.

[0062] Differential pressure build-up (different pressure requirements for the first caliper 12 and the second caliper 14): The two-position three-way valve 7 remains open between the first and second ports, while the fifth normally open valve 13 is closed. By adjusting the conduction time of the first normally open valve 8 and the third normally open valve 18, the flow rate of brake fluid delivered to the first caliper 12 and the second caliper 14 is controlled, thereby adjusting the oil pressure of the two calipers to achieve different pressure build-up requirements and meet the braking requirements of the vehicle under conditions such as steering and different road surface adhesion coefficients.

[0063] 3. Depressurization process:

[0064] Routine pressure relief (no high precision requirement): Two-position three-way valve 7 controls the connection between the second and third interfaces, the first normally open valve 8 and the third normally open valve 18 are open, the second normally open valve 9 and the fourth normally open valve 17 are open, the first normally closed valve 10 and the second normally closed valve 16 are open, and the third normally closed valve 19 is open. The brake fluid in the first caliper 12 flows back to the oil tank 21 via the first normally open valve 8, the two-position three-way valve 7, and the third normally closed valve 19, and also via the second normally open valve 9, the first normally closed valve 10, and the third normally closed valve 19. The brake fluid in the second caliper 14 flows back to the oil tank 21 via the third normally open valve 18, the two-position three-way valve 7, and the third normally closed valve 19, and also via the fourth normally open valve 17, the second normally closed valve 16, and the third normally closed valve 19, thus completing the routine pressure relief and releasing the brakes.

[0065] Precise pressure relief (high precision requirement): With the first normally open valve 8 and the third normally open valve 18 closed, the return flow rate and flow of brake fluid in the first caliper 12 are adjusted by precisely controlling the conduction duration and frequency of the second normally open valve 9 and the first normally closed valve 10, thus achieving precise pressure relief of the first caliper 12. Similarly, precise pressure relief of the second caliper 14 is achieved by controlling the conduction duration and frequency of the fourth normally open valve 17 and the second normally closed valve 16. In this way, through the dynamic adaptation deviation between the second normally open valve 9 and the first normally closed valve 10, and between the fourth normally open valve 17 and the second normally closed valve 16, a compensation effect of "1+1>2" is achieved, avoiding pressure oscillation and ensuring pressure relief accuracy.

[0066] Typical compensation scenarios are as follows:

[0067] Scenario 1: The normally closed valve has an excessively long delay (e.g., an actual delay of 25ms, exceeding the standard by 5ms):

[0068] First, send a conduction signal to the normally open valve 5ms in advance so that the normally open valve can establish a pressure relief path first; when the normally closed valve conducts 25ms later, the pressure relief has already been pre-started through the normally open valve to avoid overall pressure relief lag and to offset the delay deviation.

[0069] Scenario 2: The normally closed valve has an excessive flow rate (e.g., actual flow rate of 12 mL / s, exceeding the standard by 2 mL / s):

[0070] The normally open valve is controlled to operate in an intermittent conduction mode (e.g., conduction for 10ms, cut-off for 5ms) to reduce the overall pressure relief flow rate; at the same time, the normally closed valve is controlled to shorten the conduction time. The two work together to stabilize the total flow rate at the target value of 10mL / s and offset the flow deviation.

[0071] Scenario 3: Low-pressure leakage of normally closed valve (e.g., target pressure relief endpoint is 1MPa, actual leakage is 0.8MPa):

[0072] When the pressure relief approaches the target value, first close the normally open valve to cut off the main passage, and then use the normally closed valve in a "micro-conduction-cutoff" cycle (e.g., conduction for 2ms, cutoff for 8ms) to precisely replenish the pressure relief and stabilize the pressure at 1MPa to offset the leakage deviation.

[0073] 4. Emergency braking process under abnormal power failure:

[0074] When the system experiences an abnormal power-down, the two-position three-way valve 7 malfunctions, and the sixth normally open valve 6 automatically opens. The pressurized brake fluid in the accumulator 4 flows to the first caliper 12 via the sixth normally open valve 6 and the first normally open valve 8, and simultaneously flows to the second caliper 14 via the third normally open valve 18. The first normally closed valve 10, the second normally closed valve 16, and the third normally closed valve 19 are closed, enabling emergency pressure build-up in the first caliper 12 and the second caliper 14, completing emergency braking, and preventing the vehicle from losing braking ability due to an abnormal power-down.

[0075] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0076] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0077] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0078] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0079] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A high-precision electro-hydraulic braking system, characterized in that, include: The fuel tank is used to store brake fluid; An energy storage unit is used to build up pressure in the brake fluid; At the end of the braking operation, the braking action is achieved by pressurizing / depressurizing the brake fluid. A hydraulic control unit is configured to connect the energy storage unit to the corresponding braking actuator. The hydraulic control unit includes: A first normally open valve, one end of which is connected to the energy storage unit and the other end of which is connected to the braking actuator. A second normally open valve, one end of which is connected to the other end of the first normally open valve; A first normally closed valve, one end of which is connected to the other end of a second normally open valve, and the other end of which is connected to the oil tank; The third normally open valve, one end of which is connected to the energy storage unit, and the other end of which is connected to the braking actuator; A fourth normally open valve, one end of which is connected to the other end of the third normally open valve; The second normally closed valve has one end connected to the other end of the fourth normally open valve, and the other end of the second normally closed valve is connected to the oil tank. The braking actuator includes a first caliper and a second caliper. The other end of the first normally open valve is directly connected to the first caliper through an oil circuit, and the other end of the third normally open valve is directly connected to the second caliper through an oil circuit. It also includes a third normally closed valve, one end of which is connected to the other end of the first normally closed valve and the other end of the second normally closed valve, and the other end of the third normally closed valve is connected to the oil tank; It also includes a two-position three-way valve, which has a second port and a third port. The second port is connected to one end of the first normally open valve and one end of the third normally open valve, respectively, and the third port is connected to one end of the third normally closed valve. During normal pressure relief, the two-position three-way valve controls the second and third interfaces to be connected, the first and third normally open valves are connected, the second and fourth normally open valves are connected, the first and second normally closed valves are connected, and the third normally closed valve is connected. The brake fluid in the first caliper flows back to the oil tank through the first normally open valve, the two-position three-way valve, and the third normally closed valve, and through the second normally open valve, the first normally closed valve, and the third normally closed valve. The brake fluid in the second caliper flows back to the oil tank through the third normally open valve, the two-position three-way valve, and the third normally closed valve, and through the fourth normally open valve, the second normally closed valve, and the third normally closed valve, and through the third normally closed valve, completing the normal pressure relief and releasing the brakes. When precise pressure relief is required, the first normally open valve and the third normally open valve are shut off. By precisely controlling the conduction duration and frequency of the second normally open valve and the first normally closed valve, precise pressure relief of the first caliper is achieved. Similarly, by controlling the conduction duration and frequency of the fourth normally open valve and the second normally closed valve, precise pressure relief of the second caliper is achieved.

2. The high-precision electro-hydraulic braking system according to claim 1, characterized in that, A fifth normally open valve is provided between the first caliper and the second caliper. One end of the fifth normally open valve is connected to the oil circuit of the first caliper, and the other end is connected to the oil circuit of the second caliper.

3. The high-precision electro-hydraulic braking system according to claim 1, characterized in that, It also includes a first pressure sensor and a second pressure sensor, the first pressure sensor being used to collect the oil pressure in the oil circuit of the first caliper, and the second pressure sensor being used to collect the oil pressure in the oil circuit of the second caliper.

4. The high-precision electro-hydraulic braking system according to claim 1, characterized in that, The two-position three-way valve has a first interface, which is connected to the energy storage unit.

5. The high-precision electro-hydraulic braking system according to claim 1, characterized in that, It also includes a sixth normally open valve, which is connected in parallel with the two-position three-way valve. One end of the sixth normally open valve is connected to the energy storage unit, and the other end is connected to one end of the first normally open valve and one end of the third normally open valve.

6. The high-precision electro-hydraulic braking system according to any one of claims 1-5, characterized in that, The first normally open valve, the second normally open valve, the third normally open valve, and the fourth normally open valve are all connected in parallel with a first check valve.

7. The high-precision electro-hydraulic braking system according to any one of claims 1-5, characterized in that, The energy storage unit includes: An accumulator is used to store brake fluid pressure. A third pressure sensor is installed in the oil circuit of the accumulator to collect the pressure of the accumulator. A pump assembly, one end of which is connected to the oil tank and the other end of which is connected to the accumulator, and the pump assembly is also connected to an overflow valve; A second one-way valve is located between the pump assembly and the accumulator, with one end connected to the pump assembly and the other end connected to the accumulator, to prevent the brake fluid from flowing back.

8. The high-precision electro-hydraulic braking system according to any one of claims 1-5, characterized in that, The oil tank is equipped with a level sensor to collect the level of brake fluid in the tank.

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