Hydraulic brake-by-wire system

Abstract

The invention relates to the technical field of brake-by-wire systems, in particular to a hydraulic brake-by-wire system which has double pressure source control, a first BSM module and a second BSM module can independently provide brake fluid, when one of the first BSM module and the second BSM module loses a hydraulic power source, the other of the first BSM module and the second BSM module still has the hydraulic power source, the pressure of the first BSM module and the pressure of the second BSM module are subjected to split-axis regulation and control, and the brake fluid can be independently supplied. Compared with a traditional hydraulic braking system with four wheels controlled by the same pressure source, when a heavy-duty vehicle enters EBD control, front wheels are independently pressurized without being influenced by pressure relief of the rear wheels while pressure relief of the rear wheels, braking force loss can be reduced, the first BSM and the second BSM communicate and interact through a private CAN during normal work, and when the private CAN breaks down, the braking force loss is reduced. The first BSM transmits a pedal travel signal to the second BSM through the whole vehicle public CAN; when the first BSM breaks down, a pedal travel signal is transmitted to the second BSM through the hard wire PWM, and in addition, the liquid supply amount of brake liquid can meet the requirements for brake time and brake deceleration of a larger-tonnage automobile or truck in the mode that the two WCBSs control two wheels respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of brake-by-wire systems, and in particular to a hydraulic brake-by-wire system. Background Art

[0002] In recent years, the rapid development of electric vehicles has also driven the research and development and application of new braking systems. Wire-controlled brake systems have been extremely popular. Wire-controlled brake systems are currently divided into two main braking structures: electronic hydraulic and electronic mechanical. However, current wire-controlled brake solutions are mainly used in the field of small-tonnage passenger cars. Commercial vehicles with relatively larger curb weights are not widely used due to limitations in braking capabilities.

[0003] For example, Chinese patent publication number CN110116718A discloses a wire-controlled hydraulic braking system, which connects the solenoid valves, brushless motor, worm gear, gear rack, pedal feel simulator, master cylinder, fluid reservoir, and brake through a reasonable hydraulic circuit to achieve a fully decoupled wire-controlled hydraulic braking function. The system can complete the wire-controlled basic braking function, the pressure maintenance function of the anti-lock braking system, the pressure reduction function of the anti-lock braking system, the fluid replenishment function of the boost cylinder of the anti-lock braking system, the active boost function, and the self-detection function of detecting leakage failures in the circuit.

[0004] However, the applicant found that the hydraulic brake-by-wire system disclosed in the above-mentioned comparative patent usually controls all four brake loads (wheels) by one pressure source (boost cylinder). Due to the limitation of the brake fluid that can be provided by the boost cylinder, it can only provide the required brake fluid for small-tonnage vehicles to meet their braking time and deceleration requirements, but cannot meet the fluid volume required by the brake calipers of larger-tonnage vehicles, thereby reducing the adaptability of the hydraulic brake-by-wire system. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to propose a hydraulic brake-by-wire system to solve the problem that in existing hydraulic brake-by-wire systems, the four braking loads (wheels) are usually controlled by the same pressure source and cannot be adjusted by separate axles. When a heavily loaded vehicle enters EBD control, the rear axle releases pressure while the front wheel pressurization is easily affected by the rear wheel pressure release, which can easily cause a loss of braking force.

[0006] Based on the above-mentioned purpose, the present invention provides a hydraulic wire-controlled braking system, including a hydraulic system, which is a dual-pressure source system, composed of BSM 1 and BSM 2, and the BSM 1 and BSM 2 exchange signals through hard-line PWM, private CAN and public CAN; it also includes brake load 1, brake load 2, brake load 3, brake load 4, brake fluid flow pipeline 1 and brake fluid flow pipeline 2, the BSM 1 controls brake load 1 and brake load 2 respectively through two brake fluid flow pipelines 1, and the BSM 2 controls brake load 3 and brake load 4 respectively through two brake fluid flow pipelines 2.

[0007] Preferably, the BSM includes an ECU, a brake fluid booster system, a master cylinder, a pedal, and a displacement sensor; the master cylinder is connected to the pedal via a piston in its cylinder body, and the displacement sensor is installed on the piston in the master cylinder to achieve synchronous movement of the displacement sensor and the piston, so that the displacement sensor can detect the input push rod displacement of the pedal, and two brake fluid flow pipelines are both connected to the brake fluid booster system.

[0008] Preferably, the BSM 2 includes an ECU 2 and a brake fluid boosting system 2, the two brake fluid flow pipelines 2 are both connected to the brake fluid boosting system 2, and the ECU 1 and ECU 2 exchange signals through a private CAN and a public CAN.

[0009] Preferably, a pressure sensor is provided in the cylinder body of the master cylinder, and the pressure sensor is used to detect the pressure in the master cylinder.

[0010] Preferably, the displacement sensor interacts with the ECU via hard-wired PWM signals.

[0011] Preferably, when the private CAN fails, the BSM 2 cannot obtain the target pressure signal transmitted from the private CAN, that is, when the private CAN communication between the BSM 1 and BSM 2 fails, the BSM 1 can send the pedal travel signal of the BSM 1 to the BSM 2 through the public CAN, and the BSM 2 establishes pressure according to the internal algorithm program.

[0012] Preferably, when ECU 1 in the BSM 1 fails and cannot send signals to the private CAN and the public CAN, the displacement sensor sends the stroke PWM signal to ECU 2 via hard-line PWM, and ECU 2 builds pressure according to the received PWM signal.

[0013] The beneficial effects of the present invention are as follows: 1. With dual pressure source control, the two modules BSM 1 and BSM 2 in this system can independently provide brake fluid. When one module loses the hydraulic power source, the other module still has the hydraulic power source to provide hydraulic braking, and the two modules do not interfere with each other.

[0014] 2. Dual CAN channel redundancy. During normal operation, BSM 1 and BSM 2 communicate and exchange information through private CAN. BSM 1 transmits the driver's request for target pressure to BSM 2 through private CAN for execution. When private CAN fails, BSM 1 transmits the brake pedal travel signal to BSM 2 through the vehicle's public CAN, and BSM 2 performs pressure control according to the pedal travel.

[0015] 3. Hard-wired backup of pedal travel signal: When BSM1 fails, the displacement sensor will transmit the detected pedal travel signal to BSM2 via hard-wired PWM. BSM2 will then perform pressure control based on the pedal travel.

[0016] Fourth, the pressure axle control of BSM1 and BSM2, compared with the traditional hydraulic braking system where the four braking loads (i.e., the four wheels) are controlled by the same pressure source, allows the front wheels to be independently pressurized while the rear wheels depressurize when the heavy-duty vehicle enters EBD control, without being affected by the depressurization of the rear wheels, thus reducing the loss of braking force. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 2 is a system block diagram of an embodiment of the present invention.

[0019] In the figure: 1. BSM 1; 2. BSM 2; 3. Hard-wired PWM; 4. Private CAN; 5. Public CAN; 6. Brake load 1; 7. Brake load 2; 8. Brake load 3; 9. Brake load 4; 10. Brake fluid flow line 1; 11. Brake fluid flow line 2; 12. ECU 1; 13. Brake fluid booster system 1; 14. Master cylinder; 15. Pedal; 16. Displacement sensor; 17. ECU 2; 18. Brake fluid booster system 2; 19. Pressure sensor. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0021] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0022] like Figure 1 As shown, a hydraulic wire-controlled brake system includes a hydraulic system, which is a dual-pressure source system composed of BSM-1 and BSM-2. BSM-1 and BSM-2 exchange signals through hard-wired PWM3, private CAN4 and public CAN5; it also includes brake load-1 6, brake load-2 7, brake load-3 8, brake load-4 9, brake fluid flow line 10 and brake fluid flow line 2 11. BSM-1 controls brake load-1 6 and brake load-2 7 respectively through two brake fluid flow lines 10, and BSM-2 controls brake load-3 8 and brake load-4 9 respectively through two brake fluid flow lines 2 11.

[0023] By setting up BSM-1 and BSM-2, BSM-1 can control brake load-1 6 and brake load-2 7 respectively by controlling two brake fluid flow lines-10, while BSM-2 can control brake load-3 8 and brake load-4 9 respectively by controlling two brake fluid flow lines-2 11. This allows the two modules BSM-1 and BSM-2 in this system to independently provide brake fluid. If one of them loses its hydraulic power source, the other still has a hydraulic power source to provide hydraulic braking, and the two modules do not interfere with each other. In addition, by controlling brake load-6 and brake load-2 7 through BSM-1 and controlling brake load-3 8 and brake load-4 9 through BSM-2, the required brake fluid can be provided for large-tonnage cars or trucks. When a heavy-loaded vehicle enters EBD control, the rear wheels release pressure while the front wheels are independently pressurized without being affected by the rear wheel pressure release, thereby reducing braking force loss.

[0024] In a preferred embodiment of the present invention, BSM-1 includes ECU-12, brake fluid boosting system-13, master cylinder-14, pedal-15, and displacement sensor-16. Brake fluid boosting system-13, displacement sensor-16, and pressure sensor-19 are all electrically connected to ECU-12. Master cylinder-14 is connected to pedal-15 via a piston within its cylinder. Displacement sensor-16 is mounted on the piston within master cylinder-14 to achieve synchronous movement between displacement sensor-16 and piston, enabling displacement sensor-16 to detect the displacement of the input push rod of pedal-15. Two brake fluid flow lines-10 are both connected to brake fluid boosting system-13. Brake fluid boosting system generally refers to a system that increases braking force by increasing brake fluid pressure. Such a system can be electronically controlled or mechanically assisted. The purpose of the boosting system is to make the braking response more rapid and powerful, especially in situations requiring emergency braking. Brake fluid boosting system is a conventional technology.

[0025] When the system is powered on, and the driver presses the pedal 15 forward, the displacement sensor 16 detects that the input push rod displacement exceeds the set threshold. The ECU-12 controls the brake fluid booster system-13 to perform the pressure build-up of brake load-16 or brake load-27 based on the input push rod displacement signal of the pedal 15. At the same time, the ECU-12 transmits the displacement signal detected by the displacement sensor 16 to the BSM-2 via the private CAN4. The BSM-2, based on the received signal, controls the brake fluid flow line-211 to perform the pressure build-up of brake load-38 or brake load-49.

[0026] In another preferred embodiment of the present invention, BSM 2 includes ECU 2 17 and brake fluid boosting system 2 18, both brake fluid flow pipelines 2 11 are connected to brake fluid boosting system 2 18, and ECU 12 and ECU 2 17 exchange signals through private CAN4 and public CAN5.

[0027] A pressure sensor 19 is provided in the cylinder body of the master cylinder 14 , and the pressure sensor 19 is used to detect the pressure in the master cylinder 14 .

[0028] Dual CAN channel redundancy: During normal operation, BSM-1 and BSM-2 communicate via private CAN4. BSM-1 transmits the driver's requested target pressure to BSM-2 via private CAN4 for execution. When private CAN4 fails, BSM-2 cannot obtain the target pressure signal transmitted from private CAN4. That is, when the private CAN4 communication between BSM-1 and BSM-2 fails, BSM-1 can send the pedal travel signal of BSM-1 to BSM-2 via public CAN5. BSM-2 then establishes the pressure according to its internal algorithm.

[0029] It should be noted that the displacement sensor 16 interacts with the ECU 2 17 signals via hard-wired PWM3.

[0030] The pedal stroke signal is hard-wired for backup. When ECU-12 in BSM-1 fails and cannot send signals to private CAN4 and public CAN5, the displacement sensor 16 sends the stroke PWM signal to ECU-2 17 through hard-wire PWM3. ECU-2 17 builds pressure based on the received PWM signal.

[0031] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0032] The embodiments of the present invention are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A hydraulic brake-by-wire system, characterized in that: The invention comprises a hydraulic system, which is a dual pressure source system, and is composed of a BSM 1 (1) and a BSM 2 (2). The BSM 1 (1) and the BSM 2 (2) perform signal interaction through a hard-line PWM (3), a private CAN (4) and a public CAN (5); and further comprises a brake load 1 (6), a brake load 2 (7), a brake load 3 (8), a brake load 4 (9), a brake fluid flow pipeline 1 (10) and a brake fluid flow pipeline 2 (11). The BSM 1 (1) controls the brake load 1 (6) and the brake load 2 (7) respectively through two brake fluid flow pipelines 1 (10), and the BSM 2 (2) controls the brake load 3 (8) and the brake load 4 (9) respectively through two brake fluid flow pipelines 2 (11).

2. A hydraulic brake-by-wire system according to claim 1, characterized in that: The BSM (1) comprises an ECU (12), a brake fluid boosting system (13), a master cylinder (14), a pedal (15), and a displacement sensor (16); the master cylinder (14) is connected to the pedal (15) via a piston in its cylinder body; the displacement sensor (16) is mounted on the piston in the master cylinder (14) to achieve synchronous movement of the displacement sensor (16) and the piston, so that the displacement sensor (16) can detect the displacement of an input push rod of the pedal (15); and two brake fluid flow pipelines (10) are both connected to the brake fluid boosting system (13).

3. A hydraulic brake-by-wire system according to claim 2, characterized in that: The BSM 2 (2) includes an ECU 2 (17) and a brake fluid boosting system 2 (18), and the two brake fluid flow pipelines 2 (11) are both connected to the brake fluid boosting system 2 (18). The ECU 1 (12) and the ECU 2 (17) exchange signals via a private CAN (4) and a public CAN (5).

4. A hydraulic brake-by-wire system according to claim 2, characterized in that: A pressure sensor (19) is provided in the cylinder body of the master cylinder (14), and the pressure sensor (19) is used to detect the pressure in the master cylinder (14).

5. The hydraulic brake-by-wire system according to claim 3, characterized in that: The displacement sensor (16) interacts with ECU 2 (17) signals via hard-wired PWM (3).

6. The hydraulic brake-by-wire system according to claim 1, characterized in that: When the private CAN (4) fails, the BSM 2 (2) cannot obtain the target pressure signal transmitted from the private CAN (4), that is, when the private CAN (4) communication between the BSM 1 (1) and the BSM 2 (2) fails, the BSM 1 (1) can send the pedal travel signal of the BSM 1 (1) to the BSM 2 (2) through the public CAN (5), and the BSM 2 (2) establishes pressure according to the internal algorithm program.

7. The hydraulic brake-by-wire system according to claim 3, characterized in that: When ECU 1 (12) in the BSM 1 (1) fails and cannot send signals to the private CAN (4) and the public CAN (5), the displacement sensor (16) sends the travel PWM signal to ECU 2 (17) via the hard-line PWM (3), and ECU 2 (17) builds pressure according to the received PWM signal.

Images