Integrated Electro-Hydraulic Braking System Based on Dual-Core Single-Controlled EPB and Its Working Method

Abstract

The present invention discloses an integrated electro-hydraulic braking system based on a dual-core single-control EPB and its working method, belonging to the technical field of automotive braking. The system includes a service braking assembly, a parking braking assembly, and a dual-core single-control control assembly. The service braking assembly and the parking braking assembly are both electrically connected to the dual-core single-control control assembly. The dual-core single-control control assembly includes a main MCU and a redundant MCU that communicate with each other. The main MCU is electrically connected to the left parking brake through a main drive module, and the redundant MCU is electrically connected to the right parking brake through a redundant drive module. The dual-core single-control control assembly is connected to the service braking assembly through an HCU unit. By adopting the above integrated electro-hydraulic braking system based on a dual-core single-control EPB and its working method, the lateral, longitudinal control, and parking control are integrated, and the weight reduction of the brake is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive braking, and particularly to an integrated electro-hydraulic braking system based on dual-core single-control EPB and its working method. Background Art

[0002] An automotive braking system is a core component to ensure the safe driving of a vehicle. Its main function is to convert the kinetic energy of the vehicle into heat energy or other forms of energy through a series of mechanical, hydraulic, or electronic control means when the driver needs to decelerate or stop, and ultimately achieve effective deceleration and stopping.

[0003] The problems existing in the existing automotive braking systems mainly include the following points:

[0004] 1. Limitations in braking response speed and stability: When the traditional braking system responds to rapidly changing driving conditions, it cannot immediately provide the most ideal braking force distribution scheme, resulting in a relatively long braking response time and insufficient vehicle stability control during braking. Therefore, in emergency braking situations, it may affect driving safety.

[0005] 2. Energy consumption and emission problems: The traditional braking system fails to effectively utilize the energy generated during braking. This part of the energy is usually dissipated in the form of heat, causing energy waste and increasing the overall energy consumption and carbon dioxide emissions of the vehicle, which does not meet the modern automotive environmental protection requirements.

[0006] 3. Insufficient application of electronic control technology: Despite the continuous progress of automotive electronic technology, the traditional braking system still lags behind in terms of electronization and intelligence. It lacks an efficient electronic control unit to precisely manage the braking process, restricting the intelligent level of the braking system and its ability to adapt to complex working conditions.

[0007] 4. System complexity and weight problems: The traditional braking system has more components and a complex structure, which not only increases the total weight of the vehicle but also affects the fuel economy and dynamic performance of the vehicle, contrary to the current trend of pursuing lightweight design.

[0008] 5. Low matching degree of safety standards: With the development of intelligent driving technology, the requirements for the functional safety of the braking system in the case of no human intervention are becoming increasingly stringent, and the automotive safety integrity level of the existing braking system can no longer meet the market demand.

[0009] In summary, the traditional braking system faces challenges in terms of braking efficiency, energy utilization, intelligent level, system lightweight, and compliance with high-level safety standards. Summary of the Invention

[0010] The purpose of the present invention is to provide an integrated electro-hydraulic braking system based on dual-core single-control EPB and its working method to solve the above technical problems.

[0011] To achieve the above object, the present invention provides an integrated electro-hydraulic braking system based on a dual-core single-control EPB, which includes a service braking assembly, a parking braking assembly, and a dual-core single-control control assembly. The service braking assembly and the parking braking assembly are both electrically connected to the dual-core single-control control assembly;

[0012] The dual-core single-control control assembly includes a main MCU and a redundant MCU that communicate with each other. The main MCU is electrically connected to the left parking brake through a main drive module, and the redundant MCU is electrically connected to the right parking brake through a redundant drive module;

[0013] The dual-core single-control control assembly is connected to the service braking assembly through an HCU unit.

[0014] Preferably, the HCU unit is integrated with a first cylinder isolation valve, a second cylinder isolation valve, a first circuit switching valve, a second circuit switching valve, a test diagnosis valve, a simulator valve, and four inlet valves and four outlet valves respectively arranged for the four wheels of the vehicle;

[0015] The service braking assembly includes a liquid storage pot, a pedal braking unit and an electric cylinder braking unit that are respectively connected to the liquid storage pot through pipelines. Among them, the pedal braking unit includes a brake master cylinder with a liquid replenishing port connected to the liquid storage pot, a brake pedal, and a simulator valve. The brake master cylinder is connected to the brake pedal through a push rod. The first brake chamber of the brake master cylinder is connected to the pedal simulator through the simulator valve. A first circuit switching valve input end is connected between the brake master cylinder and the simulator valve. The output end of the first circuit switching valve is respectively connected to the inlet valves arranged on the right front wheel and the left rear wheel of the vehicle. The second brake chamber of the brake master cylinder is respectively connected to the inlet valves arranged on the left front wheel and the right rear wheel of the vehicle through a second circuit switching valve;

[0016] The electric cylinder braking unit includes a brushless motor and a brake electric cylinder connected to the output end of the brushless motor. The output end of the brake electric cylinder is respectively connected to the four inlet valves through pipelines. The four inlet valves are respectively connected to the inlet ports of four brake wheel cylinders arranged on the four wheels of the vehicle. The outlet ports of the four brake wheel cylinders are respectively connected to the LPA through the four outlet valves and are connected to the liquid storage pot.

[0017] Preferably, the brake electric cylinder is connected to the inlet valves arranged on the right front wheel and the left rear wheel of the vehicle through a first brake circuit, and the brake electric cylinder is connected to the inlet valves arranged on the left front wheel and the right rear wheel of the vehicle through a second brake circuit;

[0018] And a first cylinder isolation valve and a second cylinder isolation valve are respectively arranged on the first brake circuit and the second brake circuit between the inlet valve and the brake electric cylinder.

[0019] Preferably, a first pressure sensor is arranged on the brake electric cylinder for collecting the pressure in the brake electric cylinder cavity;

[0020] A second pressure sensor is provided on the second brake chamber of the master brake cylinder for collecting the pressure of the second brake chamber;

[0021] A non-contact travel switch is provided on the master brake cylinder. The non-contact travel switch is aligned with the push rod for collecting the travel position of the brake pedal;

[0022] A non-contact position sensor is embedded in the brushless motor for collecting the current position angle of the brushless motor;

[0023] The first pressure sensor, the second pressure sensor, the non-contact travel switch, and the non-contact position sensor are all electrically connected to the input ends of the main MCU and the redundant MCU respectively.

[0024] Preferably, the fluid replenishing port of the master brake cylinder is communicated with the fluid reservoir through a detection circuit. A test diagnostic valve is provided on the detection circuit for detecting whether the master brake cylinder leaks.

[0025] Preferably, the main drive module includes a main EPB motor drive chip and a main H-bridge that are sequentially connected between the main MCU and the left parking brake;

[0026] The redundant drive module includes a redundant EPB motor drive chip and a redundant H-bridge that are sequentially connected between the redundant MCU and the right parking brake.

[0027] Preferably, the main MCU and the redundant MCU are connected through an SPI interface, and both the main MCU and the redundant MCU are connected to the CAN bus. The CAN bus is connected to the vehicle power CAN line and the chassis CAN line.

[0028] Preferably, the main MCU and the redundant MCU are electrically connected to the main power management module and the redundant power management module respectively.

[0029] The working method of the integrated electro-hydraulic braking system based on dual-core single-control EPB includes the following steps:

[0030] S1. Initialization settings:

[0031] Close the first loop switching valve and the second loop switching valve, and open the simulator valve. At this time, the first brake chamber of the master brake cylinder is communicated with the pedal simulator through the simulator valve, and the second brake chamber of the master brake cylinder is blocked. By collecting the pressure of the second brake chamber of the master brake cylinder, the pressure of the first brake chamber of the master brake cylinder is obtained. At the same time, the braking PV curve is drawn in combination with the travel position of the brake pedal collected by the non-contact travel switch. Based on the braking PV curve, the feedback resistance of the brake pedal is adjusted;

[0032] S2. Power-on self-check:

[0033] Before power-on, open the first cylinder isolation valve and the second cylinder isolation valve, close the first loop switching valve and the second loop switching valve, close the four liquid inlet valves, the brake cylinder is blocked, then control the brushless motor to rotate forward, drive the brake cylinder to move forward, and during this process, use the first pressure sensor to collect the pressure signal of the brake cylinder. If the collected pressure signal matches the pressure output by the brushless motor, it is determined to be normal, and step S3 is executed; otherwise, it is determined to be abnormal, open the first loop switching valve, the second loop switching valve and the four liquid inlet valves, close the first cylinder isolation valve, the second cylinder isolation valve, the simulator valve and the liquid outlet valve, and use the brake master cylinder to directly build pressure on the brake wheel cylinder for braking;

[0034] S3. Apply braking pressure

[0035] Service braking: Close the first cylinder isolation valve, the second cylinder isolation valve, the first loop switching valve and the second loop switching valve. At this time, use the brake cylinder to build pressure. The dual-core single-control control assembly applies current to the brushless motor according to the acquisition signal of the non-contact travel switch, drives the brushless motor to reverse, the brake cylinder retracts, and the brake fluid in the reservoir is sucked into the brake cylinder until the set position, completing the replenishment of the brake fluid. Open the first cylinder isolation valve and the second cylinder isolation valve, control the brushless motor to rotate forward, the brake cylinder moves forward, push the brake fluid to the brake wheel cylinder to generate a braking torque. When pressure holding is required, close the liquid inlet valve and the liquid outlet valve. When pressure reduction is required, close the liquid inlet valve and open the liquid outlet valve;

[0036] Parking braking: In the initial state, the main MCU drives the left parking brake through the main EPB motor drive chip and the main H bridge, and the redundant MCU drives the right parking brake through the redundant EPB motor drive chip and the redundant H bridge for braking control. When one of the redundant MCU and the main MCU fails, the other drives the left parking brake or the right parking brake for braking control;

[0037] S4. Shutdown self-check:

[0038] Before power-off, open the first cylinder isolation valve, the second cylinder isolation valve and the first loop switching valve, and close the second loop switching valve, the liquid inlet valve and the test diagnosis valve. At this time, the brake cylinder is connected to the brake master cylinder, control the brushless motor to rotate forward, drive the brake cylinder to move forward, and during this process, use the first pressure sensor to collect the pressure signal of the brake cylinder. If the collected pressure signal matches the pressure output by the brushless motor, it is determined to be normal; otherwise, it is determined to be abnormal.

[0039] Preferably, in step S3, energy recovery is also carried out, and the energy recovery strategy is as follows:

[0040] In the initial stage of braking, if the braking torque requested by the driver is less than the maximum braking torque provided by the current vehicle energy recovery, the braking torque is entirely provided by the vehicle energy recovery; if the braking torque is greater than the maximum braking torque provided by the current vehicle energy recovery, the vehicle energy recovery provides the maximum braking torque, and at the same time, the integrated electro-hydraulic braking system based on the dual-core single-control EPB makes up for the remaining braking demand torque;

[0041] In step S3, the braking pressure is also estimated, and the estimation method is as follows:

[0042] The first cylinder isolation valve, the second cylinder isolation valve, the first circuit switching valve, the second circuit switching valve, the test diagnosis valve, the simulator valve, the four inlet valves, and the four outlet valves all use solenoid valves, and the solenoid valve core aperture flow calculation formula is as follows:

[0043] (1);

[0044] (2);

[0045] In the formula, represents the core aperture flow of the solenoid valve; represents the flow coefficient; represents the fluid inlet diameter of the solenoid valve core; represents the fluid outlet diameter of the solenoid valve core; represents the fluid outlet pressure of the solenoid valve core; represents the fluid inlet pressure of the solenoid valve core; represents the correlation coefficient between the pressure difference and the flow rate;

[0046] Combining formula (1) and formula (2), and simplifying, we get:

[0047] (3);

[0048] Then calculate the brake fluid volume of the brake wheel cylinder :

[0049] (4);

[0050] Finally, combining the relationship between the vehicle brake fluid volume and the pressure curve, the brake pressure of the brake wheel cylinder is converted. Therefore, the present invention adopts the above-mentioned integrated electro-hydraulic braking system based on the dual-core single-control EPB and its working method, and the beneficial effects are as follows:

[0051] 1. Improve the safety performance of the vehicle: Adopt the integrated design strategy, overcome the bottleneck of traditional braking technology, ensure more sensitive braking response and excellent braking stability, meet the continuously upgraded vehicle safety standards, and ensure the safety of drivers and passengers during the ride;

[0052] 2. Green energy saving: Convert the excess energy during braking into electrical energy and store it. The energy recovery rate is 13% - 20%, which can be used for the internal circulation of the vehicle, significantly improving energy efficiency and reducing energy consumption emissions.

[0053] 3. Realize wire control braking, with a performance of building pressure to 100 Bar in 150 ms; meet the requirements of intelligent driving for the braking system, and at the same time achieve decoupling of the braking system, so that the brake pedal will not fluctuate with the master cylinder pressure, improving the driver's subjective feeling of stepping on the brake pedal.

[0054] 4. Conform to the lightweight trend: Through integrated design, streamline the number and quality of braking components, reduce the load of the vehicle (system weight is less than 5.5 kg), indirectly improve the operation efficiency and fuel economy of the vehicle, and lead a new wave of lightweight in the automotive industry.

[0055] 5. By adopting the electronic parking brake system (EPB) solution of dual-core single control, improve the functional safety level of the integrated braking system to the ASIL-D level in ISO26262 functional safety.

[0056] 6. The NVH performance can meet the working noise less than 55 db.

[0057] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0058] Figure 1 It is the driving braking schematic diagram of an integrated electro-hydraulic braking system based on dual-core single control EPB of the present invention;

[0059] Figure 2 It is the parking braking schematic diagram of an integrated electro-hydraulic braking system based on dual-core single control EPB of the present invention;

[0060] Figure 3 It is the energy recovery diagram of the simulation experiment of the present invention; where (a) is the relationship diagram between braking torque and time; (b) is the relationship diagram between energy recovery torque and time; (c) is the relationship diagram between hydraulic braking torque and time;

[0061] Figure 4 It is the relationship between the vehicle brake fluid volume and pressure curve of the present invention.

[0062] Reference Signs

[0063] 1. Non-contact position sensor; 2. Brushless motor; 3. First pressure sensor; 4. Second cylinder isolation valve; 5. Second pressure sensor; 6. Liquid storage pot; 7. Test diagnostic valve; 8. Non-contact travel switch; 9. Brake pedal; 10. Simulator valve; 11. Pedal simulator; 12. First circuit switching valve; 13. Liquid inlet valve; 14. Liquid outlet valve; 15. Brake master cylinder; 16. Brake cylinder; 17. First cylinder isolation valve; 18. Second circuit switching valve. Detailed implementation mode

[0064] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0065] The following will describe in detail the implementation mode of the present invention with reference to the drawings.

[0066] As Figure 1 and Figure 2 shown, an integrated electro-hydraulic braking system based on a dual-core single-control EPB includes a service braking assembly, a parking braking assembly, and a dual-core single-control control assembly. The service braking assembly and the parking braking assembly are both electrically connected to the dual-core single-control control assembly; the dual-core single-control control assembly includes a main MCU and a redundant MCU that communicate with each other. The main MCU is electrically connected to the left parking brake through the main drive module, and the redundant MCU is electrically connected to the right parking brake through the redundant drive module; the dual-core single-control control assembly is connected to the service braking assembly through the HCU unit, thus realizing the integration of lateral, longitudinal control and parking control, and realizing the lightweight of the brake (the system weight is less than 5.5 kg).

[0067] The HCU unit is integrated with a first cylinder isolation valve 17, a second cylinder isolation valve 4, a first circuit switching valve 12, a second circuit switching valve 18, a test diagnostic valve 7, a simulator valve 10, and four liquid inlet valves 13 and four liquid outlet valves 14 respectively arranged corresponding to the four wheels of the vehicle;

[0068] The service brake assembly includes a fluid reservoir 6, a pedal brake unit and an electric cylinder brake unit that are respectively connected to the fluid reservoir 6 through pipelines. Among them, the pedal brake unit includes a brake master cylinder 15 with a fluid replenishment port connected to the fluid reservoir, a brake pedal 9, and a simulator valve 10. The brake master cylinder is connected to the brake pedal 9 through a push rod. The first brake chamber of the brake master cylinder 15 is connected to a pedal simulator 11 through the simulator valve 10. An input end of a first circuit switching valve 12 is connected between the brake master cylinder 15 and the simulator valve 10. An output end of the first circuit switching valve 12 is respectively connected to inlet valves 13 arranged on the right front wheel (FR) and the left rear wheel (RL) of the vehicle. The second brake chamber of the brake master cylinder 15 is respectively connected to the inlet valves 13 arranged on the left front wheel (FL) and the right rear wheel (RR) of the vehicle through a second circuit switching valve 18. By using the simulator valve 10, the connection between the brake master cylinder 15 and the pedal simulator 11 is realized, and the feedback of the pedal force is realized;

[0069] The electric cylinder brake unit includes a brushless motor 2 and a brake electric cylinder 16 connected to the output end of the brushless motor 2. The output end of the brake electric cylinder 16 is respectively connected to the four inlet valves 13 through pipelines. The four inlet valves 13 are respectively connected to the inlet ports of four brake wheel cylinders arranged on the four wheels of the vehicle. The outlet ports of the four brake wheel cylinders are respectively connected to an LPA (low power amplifier) through four outlet valves 14 and are connected to the fluid reservoir 6. In this embodiment, the brushless motor 2 is used for control, and the service life is longer.

[0070] The brake electric cylinder 16 is respectively connected to the inlet valves 13 arranged on the right front wheel and the left rear wheel of the vehicle through a first brake circuit. The brake electric cylinder 16 is respectively connected to the inlet valves 13 arranged on the left front wheel and the right rear wheel of the vehicle through a second brake circuit; and a first electric cylinder isolation valve 17 and a second electric cylinder isolation valve 4 are respectively arranged on the first brake circuit and the second brake circuit between the inlet valve 13 and the brake electric cylinder 16.

[0071] A first pressure sensor 3 is arranged on the brake electric cylinder 16 for collecting the pressure in the cavity of the brake electric cylinder 16; a second pressure sensor 5 is arranged on the second brake chamber of the brake master cylinder 15 for collecting the pressure of the second brake chamber; a non-contact travel switch 8 is arranged on the brake master cylinder 15. The non-contact travel switch 8 is aligned with the push rod for collecting the travel position of the brake pedal 9; a non-contact position sensor 1 is embedded in the brushless motor 2 for collecting the current position angle of the brushless motor 2. By using the non-contact travel switch 8 and the non-contact position sensor 1, the service life is increased; the first pressure sensor 3, the second pressure sensor 5, the non-contact travel switch 8, and the non-contact position sensor 1 are respectively electrically connected to the input ends of the main MCU and the redundant MCU.

[0072] The fluid replenishment port of the brake master cylinder 15 is connected to the fluid reservoir 6 through a detection circuit, and a test diagnostic valve 7 is arranged on the detection circuit for detecting whether the brake master cylinder 15 leaks.

[0073] The main drive module includes a main EPB motor drive chip and a main H-bridge that are sequentially connected between the main MCU and the left parking brake; the redundant drive module includes a redundant EPB motor drive chip and a redundant H-bridge that are sequentially connected between the redundant MCU and the right parking brake.

[0074] The main MCU and the redundant MCU are electrically connected to the main power management module and the redundant power management module respectively.

[0075] The working method of the integrated electro-hydraulic braking system based on dual-core single-control EPB includes the following steps:

[0076] S1. Initialization settings:

[0077] Close the first loop switching valve 12 and the second loop switching valve 18, and open the simulator valve 10. At this time, the first braking chamber of the brake master cylinder 15 is communicated with the pedal simulator 11 through the simulator valve 10, and the second braking chamber of the brake master cylinder 15 is blocked. By collecting the pressure of the second braking chamber of the brake master cylinder 15, the pressure of the first braking chamber of the brake master cylinder 15 is obtained. At the same time, the braking PV curve is drawn by combining the traveling position of the brake pedal 9 collected by the non-contact travel switch 8. Based on the braking PV curve, the feedback resistance of the brake pedal 9 is adjusted.

[0078] S2. Power-on self-check:

[0079] Before power-on, open the first cylinder isolation valve 17 and the second cylinder isolation valve 4, and close the first loop switching valve 12 and the second loop switching valve 18. Close the four inlet valves 13, and the brake cylinder 16 is blocked. Then control the brushless motor 2 to rotate forward to drive the brake cylinder 16 to move forward. During this process, use the first pressure sensor 3 to collect the pressure signal of the brake cylinder 16. If the collected pressure signal matches the pressure output by the brushless motor 2, it is determined to be normal, and step S3 is executed. Otherwise, it is determined to be abnormal. Open the first loop switching valve 12, the second loop switching valve 18 and the four inlet valves 13, close the first cylinder isolation valve 17, the second cylinder isolation valve 4, the simulator valve 10 and the outlet valve 14, and use the brake master cylinder 15 to directly build pressure on the brake wheel cylinder for braking.

[0080] S3. Apply braking pressure

[0081] Service braking: Close the first cylinder isolation valve 17, the second cylinder isolation valve 4, the first circuit switching valve 12, and the second circuit switching valve 18. At this time, build pressure using the brake cylinder 16. The dual-core single-control control assembly applies current to the brushless motor 2 according to the acquisition signal of the non-contact travel switch 8, driving the brushless motor 2 to reverse. The brake cylinder 16 retracts, and the brake fluid in the reservoir 6 is sucked into the brake cylinder 16 until the set position, completing the replenishment of the brake fluid. Open the first cylinder isolation valve 17 and the second cylinder isolation valve 4, control the brushless motor 2 to rotate forward, and the brake cylinder 16 advances, pushing the brake fluid to the brake wheel cylinder to generate a braking torque. When pressure holding is required, close the inlet valve 13 and the outlet valve 14. When pressure reduction is required, close the inlet valve 13 and open the outlet valve 14 for pressure reduction. In this embodiment, the conventional pressure reduction is 180 bar, and the maximum pressure reduction is 250 bar;

[0082] Parking braking: In the initial state, the main MCU controls the left parking brake through the main EPB motor drive chip and the main H-bridge, and the redundant MCU controls the right parking brake through the redundant EPB motor drive chip and the redundant H-bridge. When one of the redundant MCU and the main MCU fails, the other drives the left parking brake or the right parking brake for braking control;

[0083] In step S3, energy recovery is also performed, and the energy recovery strategy is as follows:

[0084] In the primary stage of braking, if the braking torque requested by the driver is less than the maximum braking torque provided by the current vehicle energy recovery, the braking torque is entirely provided by the vehicle energy recovery; if the braking torque is greater than the maximum braking torque provided by the current vehicle energy recovery, the vehicle energy recovery provides the maximum braking torque, and at the same time, the integrated electro-hydraulic braking system based on the dual-core single-control EPB makes up for the remaining braking demand torque;

[0085] Simulation experiment:

[0086] As Figure 3 shown, the braking torque can be divided into four intervals as the vehicle speed decreases. In the first interval, only the braking torque generated by the vehicle energy recovery; in the second interval, the maximum braking torque generated by the vehicle energy recovery and the variable hydraulic braking torque jointly provide the braking torque; in the third interval, the braking torque generated by the vehicle energy recovery and the braking torque generated by the hydraulic braking jointly and stably provide the braking torque; in the fourth interval, due to the decrease in vehicle speed, the braking torque generated by the vehicle energy recovery gradually decreases, and the hydraulic braking torque increases equivalently.

[0087] In step S3, the braking pressure is also estimated, and the estimation method is as follows:

[0088] The first electric cylinder isolation valve, the second electric cylinder isolation valve, the first circuit switching valve, the second circuit switching valve, the test and diagnosis valve, the simulator valve, four liquid inlet valves, and four liquid outlet valves are all selected as solenoid valves. The core aperture flow calculation formula of the solenoid valve is as follows:

[0089] (1);

[0090] (2);

[0091] In the formula, represents the core aperture flow of the solenoid valve; represents the flow coefficient; represents the fluid inlet diameter of the valve core of the solenoid valve; represents the fluid outlet diameter of the valve core of the solenoid valve; represents the fluid outlet pressure of the valve core of the solenoid valve; represents the fluid inlet pressure of the valve core of the solenoid valve; represents the correlation coefficient between the pressure difference and the flow rate;

[0092] Combining formula (1) and formula (2), and simplifying, we get:

[0093] (3);

[0094] Then calculate the brake fluid volume of the brake wheel cylinder :

[0095] (4);

[0096] Finally, combining the relationship between the vehicle brake fluid volume and pressure curve as shown in Figure 4 , convert the brake pressure of the brake wheel cylinder.

[0097] S4. Shutdown self-check:

[0098] Before powering off, turn on the first electric cylinder isolation valve, the second electric cylinder isolation valve, and the first circuit switching valve, and turn off the second circuit switching valve, the liquid inlet valve, and the test and diagnosis valve. At this time, the brake electric cylinder is connected to the brake master cylinder. Control the brushless motor to rotate forward to drive the brake electric cylinder to move forward. During this process, use the first pressure sensor to collect the pressure signal of the brake electric cylinder. If the collected pressure signal matches the pressure output by the brushless motor, it is determined to be normal; otherwise, it is determined to be abnormal.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements do not enable the modified technical solutions to depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. An integrated electro-hydraulic brake system based on a dual-core single-control EPB, characterized in that: It includes a service brake assembly, a parking brake assembly and a dual-core single-control control assembly, and the service brake assembly and the parking brake assembly are both electrically connected to the dual-core single-control control assembly; The dual-core single-control control assembly includes a main MCU and a redundant MCU that communicate with each other, the main MCU is electrically connected to the left parking brake via the main drive module, and the redundant MCU is electrically connected to the right parking brake via the redundant drive module; The dual-core single-control control assembly is connected to the service brake assembly via the HCU unit; The HCU unit integrates the first electric cylinder isolation valve, the second electric cylinder isolation valve, the first circuit switching valve, the second circuit switching valve, the test diagnosis valve, the simulator valve, and four liquid inlet valves and four liquid outlet valves arranged corresponding to the four wheels of the vehicle respectively; The service brake assembly includes a fluid reservoir, a pedal brake unit and an electric cylinder brake unit respectively connected to the fluid reservoir via pipelines, wherein the pedal brake unit includes a brake master cylinder, a brake pedal and a simulator valve connected to the fluid reservoir, the brake master cylinder is connected to the brake pedal via a push rod, the first brake chamber of the brake master cylinder is connected to the pedal simulator via a simulator valve, the brake master cylinder and the simulator valve are connected via an input end of a first circuit switching valve, the output end of the first circuit switching valve is respectively connected to the fluid inlet valves arranged on the right front wheel and the left rear wheel of the vehicle, and the second brake chamber of the brake master cylinder is respectively connected to the fluid inlet valves arranged on the left front wheel and the right rear wheel of the vehicle via a second circuit switching valve; The electric cylinder brake unit includes a brushless motor and a brake electric cylinder connected to the output end of the brushless motor, the output end of the brake electric cylinder is respectively connected to four liquid inlet valves through pipelines, the four liquid inlet valves are respectively connected to the liquid inlets of four brake wheel cylinders arranged on four wheels of the vehicle, and the liquid outlets of the four brake wheel cylinders are respectively connected to the LPA through four liquid outlet valves and connected to the liquid storage pot; The brake cylinder is communicated with the fluid inlet valves arranged on the right front wheel and the left rear wheel of the vehicle respectively through the first brake circuit, and the brake cylinder is communicated with the fluid inlet valves arranged on the left front wheel and the right rear wheel of the vehicle respectively through the second brake circuit; A first electric cylinder isolation valve and a second electric cylinder isolation valve are respectively provided on the first brake circuit and the second brake circuit between the liquid inlet valve and the brake electric cylinder; The brake cylinder is provided with a first pressure sensor for collecting the pressure of the brake cylinder cavity; A second pressure sensor is provided on the second brake chamber of the brake master cylinder, for collecting the pressure of the second brake chamber; A non-contact travel switch is provided on the brake master cylinder, and the non-contact travel switch is aligned with the push rod to collect the travel position of the brake pedal; A non-contact position sensor is embedded in the brushless motor to collect the current position angle of the brushless motor; The first pressure sensor, the second pressure sensor, the non-contact travel switch and the non-contact position sensor are electrically connected to the input terminals of the main MCU and the redundant MCU respectively; The fluid filling port of the brake master cylinder is connected to the fluid storage pot via a detection circuit, and a test diagnosis valve is provided on the detection circuit to detect whether the brake master cylinder is leaking; The main drive module includes a main EPB motor drive chip and a main H-bridge which are sequentially connected between the main MCU and the left parking brake; The redundant drive module includes a redundant EPB motor drive chip and a redundant H-bridge which are sequentially connected between the redundant MCU and the right parking brake.

2. The integrated electro-hydraulic brake system based on dual-core single-control EPB according to claim 1 is characterized in that: The main MCU and the redundant MCU are connected via the SPI interface, and both the main MCU and the redundant MCU are connected to the CAN bus, and the CAN bus is connected to the vehicle power CAN line and the chassis CAN line.

3. The integrated electro-hydraulic brake system based on dual-core single-control EPB according to claim 1 is characterized in that: The main MCU and the redundant MCU are electrically connected to the main power management module and the redundant power management module respectively.

4. The working method of the integrated electro-hydraulic brake system based on the dual-core single-control EPB as described in claim 2 or 3, characterized in that: The following steps are involved: S1. Initialization settings: Close the first circuit switching valve and the second circuit switching valve, and open the simulator valve. At this time, the first brake chamber of the brake master cylinder is connected to the pedal simulator through the simulator valve, and the second brake chamber of the brake master cylinder is blocked. The pressure of the first brake chamber of the brake master cylinder is obtained by collecting the pressure of the second brake chamber of the brake master cylinder. At the same time, the brake PV curve is drawn in combination with the brake pedal travel position collected by the non-contact stroke switch. Based on the brake PV curve, the feedback resistance of the brake pedal is adjusted; S2, power on self-test: Before power-on, open the first electric cylinder isolation valve and the second electric cylinder isolation valve, and close the first circuit switching valve and the second circuit switching valve, close the four liquid inlet valves, the brake cylinder is blocked, and then control the brushless motor to rotate forward to drive the brake cylinder forward, and use the first pressure sensor to collect the pressure signal of the brake cylinder in this process. If the collected pressure signal matches the pressure output by the brushless motor, it is determined to be normal and execute step S3. Otherwise, it is determined to be abnormal, open the first circuit switching valve, the second circuit switching valve and the four liquid inlet valves, close the first electric cylinder isolation valve, the second electric cylinder isolation valve, the simulator valve and the liquid outlet valve, and use the brake master cylinder to directly build pressure and brake the brake wheel cylinder; S3, apply brake pressure Service brake: close the first electric cylinder isolation valve, the second electric cylinder isolation valve, the first circuit switching valve and the second circuit switching valve. At this time, the brake cylinder is used to build pressure. The dual-core single-control control assembly applies current to the brushless motor according to the collected signal of the non-contact stroke switch, drives the brushless motor to reverse, and the brake cylinder retreats. The brake fluid in the reservoir is sucked into the brake cylinder until it reaches the set position, and the brake fluid is replenished. Open the first electric cylinder isolation valve and the second electric cylinder isolation valve, control the brushless motor to rotate forward, and the brake cylinder moves forward to push the brake fluid to the brake wheel cylinder to generate braking torque. When pressure maintenance is required, close the inlet valve and the outlet valve. When pressure reduction is required, close the inlet valve and open the outlet valve. Parking brake: In the initial state, the main MCU drives the left parking brake through the main EPB motor driver chip and the main H-bridge for braking control, and the redundant MCU drives the right parking brake through the redundant EPB motor driver chip and the redundant H-bridge for braking control. When one of the redundant MCU and the main MCU fails, the other drives the left parking brake or the right parking brake for braking control; S4, shutdown self-test: Before powering off, open the first electric cylinder isolation valve, the second electric cylinder isolation valve and the first circuit switching valve, and close the second circuit switching valve, the liquid inlet valve and the test diagnosis valve. At this time, the brake cylinder is connected to the brake master cylinder, and the brushless motor is controlled to rotate forward to drive the brake cylinder forward. In this process, the first pressure sensor is used to collect the pressure signal of the brake cylinder. If the collected pressure signal matches the pressure output by the brushless motor, it is judged to be normal, otherwise it is judged to be abnormal.

5. The working method of the integrated electro-hydraulic brake system based on the dual-core single-control EPB as claimed in claim 4, characterized in that: In step S3, energy recovery is also performed, and the energy recovery strategy is as follows: In the initial stage of braking, if the braking torque requested by the driver is less than the maximum braking torque provided by the current vehicle energy recovery, the braking torque is provided entirely by the vehicle energy recovery; if the braking torque is greater than the maximum braking torque provided by the current vehicle energy recovery, the vehicle energy recovery provides the maximum braking torque, and at the same time, the integrated electro-hydraulic braking system based on the dual-core single-control EPB as described above makes up for the remaining braking demand torque; In step S3, the brake pressure is estimated by: The first electric cylinder isolation valve, the second electric cylinder isolation valve, the first circuit switching valve, the second circuit switching valve, the test diagnosis valve, the simulator valve, the four liquid inlet valves and the four liquid outlet valves are all solenoid valves, and the calculation formula of the core aperture flow of the solenoid valve is as follows: In the formula, Q represents the core aperture flow rate of the solenoid valve; A2 represents the flow coefficient; d1 represents the valve core fluid inlet diameter of the solenoid valve; d2 represents the valve core fluid outlet diameter of the solenoid valve; P1 represents the valve core fluid outlet pressure of the solenoid valve; P2 represents the valve core fluid inlet pressure of the solenoid valve; K represents the correlation coefficient between pressure difference and flow rate; Combining formula (1) and formula (2), we can simplify and obtain: Then calculate the brake fluid volume v of the brake wheel cylinder: v = Q × t (4); Finally, the brake pressure of the wheel cylinder is calculated based on the relationship between the vehicle's brake fluid volume and pressure curve.

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