阅读说明：本技术 一种模拟器制动系统及控制方法 (Simulator braking system and control method ) 是由 李丰军 周剑光 刘宏伟 于 2021-07-30 设计创作，主要内容包括：本发明涉及车辆制动技术领域,公开了一种模拟器制动系统,通过为制动轮缸提供制动油的液压驱动单元,使液压驱动单元能为液控阀的控制端提供信号油,使液控阀开启时液控阀允许第一主缸内的制动油流向踏板模拟器,实现液控阀开启前驾驶员不会感受到踏板感；在液控阀开启后由踏板模拟器提供真实的踏板感,以提高模拟器制动系统的可靠性；无需为液控阀通电,解决了采用模拟器控制阀连通第一主缸和踏板模拟器时模拟器控制阀长时间通电会造成线圈发热的问题。本发明还提供了上述模拟器制动系统的控制方法,能够避免踏板模拟器开始动作之前驾驶员感受到踏板感,实现踏板感完全由踏板模拟器提供。(The invention relates to the technical field of vehicle braking, and discloses a simulator braking system.A hydraulic driving unit for providing braking oil for a brake wheel cylinder is used for enabling the hydraulic driving unit to provide signal oil for a control end of a hydraulic control valve, so that the hydraulic control valve allows the braking oil in a first main cylinder to flow to a pedal simulator when the hydraulic control valve is opened, and a driver does not feel pedal feeling before the hydraulic control valve is opened; after the hydraulic control valve is opened, a real pedal feeling is provided by the pedal simulator, so that the reliability of a simulator braking system is improved; need not to be for the circular telegram of liquid accuse valve, solved and adopted the simulator control valve to communicate first master cylinder and footboard simulator when simulator control valve is electrified for a long time and can cause the problem that the coil generates heat. The invention also provides a control method of the simulator brake system, which can prevent a driver from feeling pedal feel before the pedal simulator starts to act and realize that the pedal feel is completely provided by the pedal simulator.)

1. A simulator brake system comprises a brake pedal (1), a first master cylinder (2) connected with the brake pedal (1), a pedal stroke detection unit used for sensing the position change of the brake pedal (1) to form a brake stroke signal, a pedal simulator (3), a brake wheel cylinder (10) and a hydraulic drive unit used for providing brake oil for the brake wheel cylinder (10); it is characterized by also comprising:

the hydraulic control valve (4) is connected between the first master cylinder (2) and the pedal simulator (3), and the hydraulic driving unit can provide signal oil for a control end of the hydraulic control valve (4) so that the first master cylinder (2) is communicated with the pedal simulator (3) when the hydraulic control valve (4) is opened;

and the electric control unit is used for controlling the hydraulic driving unit to act according to the brake stroke signal.

2. The simulator brake system according to claim 1, wherein the pilot-controlled valve (4) comprises a pilot-controlled check valve, and the pilot-controlled valve (4) allows the brake oil in the first master cylinder (2) to flow to the pedal simulator (3) when the hydraulic drive unit supplies the signal oil to the pilot end of the pilot-controlled valve (4).

3. The simulator braking system of claim 1, further comprising:

and the simulator control valve (5) is arranged on a control oil way (15) connecting the hydraulic drive unit and the control end, and the simulator control valve (5) is used for controlling the connection or disconnection of the control oil way (15).

4. The simulator braking system of claim 3, further comprising:

and the energy storage unit is arranged on the control oil way (15) between the simulator control valve (5) and the control end.

5. Simulator brake system according to claim 4, characterized in that the simulator control valve (5) is a normally open solenoid valve.

6. Simulator brake system according to claim 3, characterized in that the simulator control valve (5) is a normally closed solenoid valve.

7. The simulator braking system of claim 6, further comprising:

the simulator pressure relief control valve (12), simulator pressure relief control valve (12) can make control oil circuit (15) and hydraulic tank communicate or break off, simulator pressure relief control valve (12) with the connected position of control oil circuit (15) is located between simulator control valve (5) and the control end of pilot operated valve (4).

8. Simulator brake system according to claim 7, characterized in that the simulator pressure relief control valve (12) is a normally open solenoid valve.

9. The simulator braking system of claim 1, further comprising:

a wheel cylinder isolation valve (9) through which the hydraulic drive unit communicates with or disconnects from the brake wheel cylinder (10).

10. The simulator brake system according to claim 9, wherein the wheel cylinder isolation valve (9) is a normally closed solenoid valve.

11. The simulator braking system according to any one of claims 1 to 10, wherein the hydraulic drive unit comprises:

the motor (6), the said motor (6) is connected electrically with the said electronic control unit;

and the output shaft of the motor (6) is in transmission connection with the piston of the second master cylinder (8), the second master cylinder (8) is used for providing signal oil for the control end, and the second master cylinder (8) is used for supplying brake oil for the brake wheel cylinder (10).

12. A control method of a simulator brake system according to any one of claims 1 to 11, comprising the steps of:

obtaining a braking stroke signal collected by the pedal stroke detection unit;

and controlling the hydraulic driving unit to work according to the braking stroke signal, so that the hydraulic driving unit can provide signal oil for the control end of the hydraulic control valve (4) to open the hydraulic control valve (4).

13. The control method of a simulator brake system according to claim 12, wherein before controlling the operation of the hydraulic drive unit according to the brake stroke signal, it is judged whether the brake pedal (1) reaches a preset position according to the brake stroke signal, and when the brake pedal (1) reaches the preset position, the operation of the hydraulic drive unit is controlled according to the brake stroke signal;

the position of the brake pedal (1) at the end of preloading of the brake wheel cylinder (10) is a specified position, and when the brake pedal (1) is located at a preset position, the brake pedal (1) does not exceed the specified position.

14. The control method of a simulator brake system according to claim 12, characterized in that after the pilot control valve (4) is opened, if the ABS or ESC function is opened, the hydraulic drive unit is controlled to stop supplying the signal oil to the control end of the pilot control valve (4).

15. A control method of a simulator brake system according to claim 12, characterized in that a simulator control valve (5) and an energy storage unit are provided between the hydraulic drive unit and the control end of the pilot operated valve (4);

after the hydraulic control valve (4) is opened, if the oil pressure of the brake wheel cylinder (10) reaches the target oil pressure, the simulator control valve (5) is controlled to stop the hydraulic driving unit to provide signal oil for the control end of the hydraulic control valve (4), and the control valve (4) is kept in an opening state under the action of the energy storage unit.

Technical Field

The invention relates to the technical field of vehicle braking, in particular to a simulator braking system and a control method.

Background

The brake system is an important guarantee for the running safety of the automobile, and along with the development of automobile intellectualization, the simulator brake system gradually replaces the traditional brake system and is widely applied. The existing simulator braking system comprises a brake pedal, a brake master cylinder assembly, a pedal simulator, a brake wheel cylinder assembly, a motor and a servo master cylinder, wherein the brake master cylinder assembly is connected with the pedal simulator through a simulator control valve which is a normally closed electromagnetic valve; the motor controls the servo main cylinder to act so as to provide signal oil for the brake wheel cylinder assembly.

The simulator brake system provides the pedal feeling by the following process: a driver inputs a braking request by stepping on a brake pedal, a brake master cylinder assembly responds to the braking request, and a brake stroke signal of the brake pedal is obtained through a pedal stroke sensor arranged in the brake master cylinder assembly; controlling a simulator control valve to be electrified according to a brake stroke signal of a brake pedal, opening the simulator control valve, enabling a brake pedal assembly to send brake oil into a pedal simulator by controlling the simulator control valve, and providing pedal feeling by the pedal simulator; meanwhile, the motor is controlled according to the brake stroke signal of the brake pedal to drive the servo master cylinder to act so as to provide signal oil for the brake wheel cylinder assembly, so that the brake wheel cylinder assembly provides braking force.

When the simulator braking system is adopted, the simulator control valve is a normally closed electromagnetic valve, the simulator control valve needs to be continuously electrified when a braking request is made, and a coil of the simulator control valve continuously heats, so that the reliability of the simulator control valve is reduced, the reliability of the simulator braking system is reduced, and the braking safety is directly influenced.

In order to solve the above technical problems, the prior art proposes: the outlet of the brake master cylinder is communicated with the control end of the hydraulic control one-way valve through a simulator control valve, and the outlet of the simulator control valve is communicated with the inlet of the pedal simulator through the hydraulic control one-way valve. When the brake pedal is stepped on, the control simulator control valve is powered on, part of brake oil in the brake master cylinder enters the control end of the hydraulic control one-way valve through the simulator control valve, when the opening degree of the brake pedal reaches a certain opening degree, the hydraulic control one-way valve is opened, then the control simulator control valve is controlled to be powered off, the control end of the hydraulic control one-way valve is filled with signal oil to maintain the opening state, and the brake master cylinder provides brake oil for the pedal simulator through the hydraulic control one-way valve.

Adopt above-mentioned technical scheme simulator control valve to only need open for a short time, solved the long-time circular telegram of simulator control valve and caused the problem of generating heat, still have following technical problem: when a brake pedal is stepped on for braking, a brake master cylinder is required to provide brake oil for a control end of a hydraulic control one-way valve, and the hydraulic control one-way valve can be opened only when the opening degree of the brake pedal reaches a certain degree, so that the brake master cylinder provides enough brake oil to enable the oil pressure of the control end of the hydraulic control one-way valve to reach an opening oil pressure, and the brake pedal generates pedal feel before the hydraulic control one-way valve is opened; after the hydraulic control one-way valve is opened, the pedal simulator provides pedal feeling, and the pedal feeling before the hydraulic control one-way valve is opened is not provided by the pedal simulator, so that false pedal feeling can be brought to a driver; and the pedal feel can obviously change before and after the hydraulic control one-way valve is opened, which can cause the pedal feel to be disordered.

Disclosure of Invention

An object of the present invention is to provide a simulator brake system capable of preventing a driver from feeling a pedal feel before a pedal simulator starts to operate.

In order to achieve the purpose, the invention adopts the following technical scheme:

the simulator brake system comprises a brake pedal, a first master cylinder connected with the brake pedal, a pedal stroke detection unit used for sensing the position change of the brake pedal to form a brake stroke signal, a pedal simulator, a brake wheel cylinder and a hydraulic drive unit used for providing brake oil for the brake wheel cylinder; further comprising:

the hydraulic control valve is connected between the first main cylinder and the pedal simulator, and the hydraulic driving unit can provide signal oil for a control end of the hydraulic control valve so that the first main cylinder and the pedal simulator are communicated when the hydraulic control valve is opened;

and the electric control unit is used for controlling the hydraulic driving unit to act according to the brake stroke signal.

As a preferable mode of the simulator brake system, the hydraulic control valve includes a hydraulic control check valve that allows the brake oil in the first master cylinder to flow to the pedal simulator when the hydraulic drive unit supplies the signal oil to the control end of the hydraulic control valve.

As a preferable technical solution of the above simulator braking system, the simulator braking system further includes:

and the simulator control valve is arranged on a control oil path connecting the hydraulic drive unit and the control end and is used for controlling the connection or disconnection of the control oil path.

As a preferable technical solution of the above simulator braking system, the simulator braking system further includes:

and the energy storage unit is arranged on the control oil path between the simulator control valve and the control end.

As a preferable technical solution of the above simulator braking system, the simulator control valve is a normally closed solenoid valve.

As a preferable technical solution of the above simulator braking system, the simulator control valve is a normally open solenoid valve.

As a preferable technical solution of the above simulator braking system, the simulator braking system further includes:

and the simulator pressure relief control valve can enable the control oil way to be communicated with or disconnected from the hydraulic oil tank, and the communication position of the simulator pressure relief control valve and the control oil way is positioned between the simulator control valve and the control end of the hydraulic control valve.

As a preferable technical solution of the above simulator braking system, the simulator pressure relief control valve is a normally open solenoid valve.

As a preferable technical solution of the above simulator braking system, the simulator braking system further includes:

a wheel cylinder isolation valve through which the hydraulic drive unit is communicated with or disconnected from the brake wheel cylinder.

As a preferable mode of the simulator brake system, the wheel cylinder isolation valve is a normally closed solenoid valve.

As a preferable aspect of the above simulator brake system, the hydraulic drive unit includes:

the motor is electrically connected with the electric control unit;

and the output shaft of the motor is in transmission connection with a piston of the second master cylinder, the second master cylinder is used for providing signal oil for the control end, and the second master cylinder is used for supplying brake oil for the brake wheel cylinder.

Another object of the present invention is to provide a control method of the above simulator brake system, which can prevent the driver from feeling a pedal feel before the pedal simulator starts to operate.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method of controlling a simulator brake system, comprising the steps of:

obtaining a braking stroke signal collected by the pedal stroke detection unit;

and controlling the hydraulic driving unit to work according to the brake stroke signal, so that the hydraulic driving unit can provide signal oil for a control end of the hydraulic control valve to open the hydraulic control valve.

As a preferred technical solution of the control method of the simulator braking system, before the hydraulic driving unit is controlled to operate according to the braking stroke signal, whether a braking pedal reaches a preset position is judged according to the braking stroke signal, and when the braking pedal reaches the preset position, the hydraulic driving unit is controlled to operate according to the braking stroke signal;

the position of the brake pedal when the preloading of the brake wheel cylinder is finished is a specified position, and when the brake pedal is located at a preset position, the brake pedal does not exceed the specified position.

As a preferable technical solution of the control method of the simulator brake system, after the pilot control valve is opened, if the ABS or ESC function is opened, the hydraulic drive unit is controlled to stop providing the signal oil to the control end of the pilot control valve.

As a preferable technical solution of the control method of the simulator brake system, a simulator control valve and an energy storage unit are arranged between the hydraulic drive unit and the control end of the hydraulic control valve;

after the hydraulic control valve is opened, if the oil pressure of the brake wheel cylinder reaches the target oil pressure, the simulator control valve is controlled to stop the hydraulic driving unit to provide signal oil for the control end of the hydraulic control valve, and the control valve is kept in an opening state under the action of the energy storage unit.

The invention has the beneficial effects that: according to the simulator braking system, the hydraulic driving unit which provides the brake oil for the brake wheel cylinder provides the signal oil for the control end of the hydraulic control valve, so that the hydraulic control valve allows the brake oil in the first main cylinder to flow to the pedal simulator when the hydraulic control valve is opened, and a driver cannot feel pedal feeling before the hydraulic control valve is opened; after the hydraulic control valve is opened, the pedal simulator provides real pedal feeling so as to improve the reliability of the simulator braking system.

The hydraulic driving unit provides signal oil for the control end of the hydraulic control valve to realize the on-off control of the hydraulic control valve, the hydraulic control valve does not need to be electrified, and the problem that the coil generates heat when the simulator control valve is electrified for a long time when the simulator control valve is used for communicating the first main cylinder with the pedal simulator is solved.

According to the simulator brake system control method provided by the invention, the hydraulic drive unit is controlled to act according to the brake stroke signal of the pedal stroke detection unit, so that the hydraulic drive unit can provide signal oil for the control end of the hydraulic control valve, and the hydraulic control valve allows the brake oil in the first main cylinder to flow to the pedal simulator when the hydraulic control valve is opened, so that a driver can not feel pedal feeling before the hydraulic control valve is opened; after the hydraulic control valve is opened, a real pedal feeling is provided by the pedal simulator, so that the reliability of a simulator braking system is improved; the problem of in the prior art can produce the footboard feel before the footboard simulator begins to act when providing signal oil for liquid accuse check valve by first master cylinder is solved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.

FIG. 1 is a schematic diagram of a simulator brake system provided in accordance with an embodiment of the present invention;

FIG. 2 is a flow chart of a method for controlling a brake system of a simulator according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a simulator braking system provided in accordance with a second embodiment of the present invention;

fig. 4 is a flowchart of a simulator braking system control method according to a second embodiment of the present invention.

In the figure:

1. a brake pedal; 2. a first master cylinder; 3. a pedal simulator; 4. a hydraulic control valve; 5. a simulator control valve; 6. a motor; 7. a transmission member; 8. a second master cylinder; 9. a wheel cylinder isolation valve; 10. a brake wheel cylinder; 11. an accumulator; 12. a simulator pressure relief control valve; 13. a first oil passage; 14. a second oil passage; 15. and controlling the oil path.

Detailed Description

In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the elements associated with the present invention are shown in the drawings.

Example one

Fig. 1 is a schematic diagram of a simulator brake system provided in the present embodiment. As shown in fig. 1, the present embodiment provides a simulator braking system, which includes a brake pedal 1 and a first main cylinder 2, wherein the brake pedal 1 is connected to the first main cylinder 2, specifically, the first main cylinder 2 includes a cylinder body and a piston slidably disposed in the cylinder body, one end of the brake pedal 1 is hinged to an input end of a pedal transmission assembly, and the other end is used for stepping; the output end of the pedal transmission assembly is hinged with the piston of the first master cylinder 2. When the brake pedal 1 is stepped, the brake pedal 1 drives the piston of the first main cylinder 2 to move in the cylinder body through the pedal transmission assembly, and then the brake oil in the first main cylinder 2 flows out to the valve and the structural member connected with the brake oil. The pedal transmission assembly may be a pedal rod, or may be other structures capable of realizing power transmission between the brake pedal 1 and the piston of the first master cylinder 2, and details thereof will not be described herein.

The simulator braking system further comprises a brake wheel cylinder 10, a hydraulic driving unit and an electronic control unit, wherein the electronic control unit is electrically connected with the hydraulic driving unit, and the hydraulic driving unit can receive a control command of the electronic control unit to provide brake oil for the brake wheel cylinder 10, so that the brake wheel cylinder 10 controls a brake caliper to perform a braking action.

The electric control unit is electrically connected with a pedal stroke detection unit, the pedal stroke detection unit senses the position change of the brake pedal 1 to form a brake stroke signal, and the electric control unit can receive the brake stroke signal of the pedal stroke detection unit. The pedal stroke detecting means may be a displacement sensor for detecting a displacement of the brake pedal 1, an angle sensor for detecting a rotation angle of the brake pedal 1 about its rotation axis, or the like, and may be a displacement sensor for detecting a piston displacement of the first master cylinder 2, a pressure sensor for detecting an output hydraulic pressure of the brake oil output from the first master cylinder 2, or the like, which are not illustrated herein.

When a driver steps on or releases the brake pedal 1, the pedal stroke detection unit can form a brake stroke signal to show whether the driver has the operation of braking or braking release, and the electronic control unit can receive the brake stroke signal of the pedal stroke detection unit, convert the brake stroke signal into a target braking force request signal, and control the hydraulic drive unit to operate according to the target braking force request signal so as to provide brake oil for the brake wheel cylinder 10 and enable the brake wheel cylinder 10 to operate.

It should be noted that the electronic control unit may be a centralized or distributed controller, for example, it may be a single-chip microcomputer or may be formed by a plurality of distributed single-chip microcomputers, and the single-chip microcomputers may run a control program and perform signal transmission, so as to control each component to implement its function.

In order to realize that the hydraulic driving unit supplies brake oil to the brake wheel cylinders 10, the hydraulic driving unit comprises the motor 6 and the second main cylinder 8, wherein the motor 6 is electrically connected with the electronic control unit, the output shaft of the motor 6 is in transmission connection with the pistons of the second main cylinder 8, and the second main cylinder 8 supplies brake oil to the brake wheel cylinders 10 through the second oil path 14 so as to actuate the brake calipers. In other embodiments, the hydraulic driving unit may also use a motor to drive a hydraulic pump to work, and the hydraulic pump supplies brake oil to the brake wheel cylinder 10.

In this embodiment, the motor 6 is a motor capable of rotating, an output shaft of the motor 6 is connected with the piston of the second master cylinder 8 through a transmission member 7, and the rotation of the output shaft of the motor 6 is converted into the movement of the piston of the second master cylinder 8 by using the transmission member 7; the transmission member 7 is a rack and pinion structure, a nut and screw structure, or a worm and gear structure, and will not be described in detail. In other embodiments, the motor 6 may also be a linear motor, and an output shaft of the motor 6 may be directly connected to the piston of the second master cylinder 8, and the linear motor directly controls the piston of the second master cylinder 8.

Further, the motor 6 is a servo motor, and the second master cylinder 8 is a servo cylinder, so that control accuracy is improved. It should be noted that the motor 6 is not limited to a servo motor, and a general motor may be used.

The simulator braking system further comprises a hydraulic control valve 4 and a pedal simulator 3, wherein the hydraulic control valve 4 is connected between the first main cylinder 2 and the pedal simulator 3, and the hydraulic driving unit can provide signal oil for a control end of the hydraulic control valve 4 through a control oil path 15, so that the hydraulic control valve 4 allows the brake oil in the first main cylinder 2 to flow to the pedal simulator 3. Specifically, the first master cylinder 2 is communicated with the pedal simulator 3 through a first oil path 13, the hydraulic control valve 4 is disposed on the first oil path 13, and the second oil path 14 is communicated with a control end of the hydraulic control valve 4 through a control oil path 15 to provide signal oil to the control end to open the hydraulic control valve 4.

Considering that the oil pressure of the brake wheel cylinder 10 is usually greater than the oil pressure of the first master cylinder 2, even several times the oil pressure of the first master cylinder 2 during braking, when the hydraulic drive unit is operated by selecting the hydraulic control valve 4 with a proper opening oil pressure, the brake oil provided by the hydraulic drive unit enters the control end of the hydraulic control valve 4 through the control oil path 15, the oil pressure at the control end of the hydraulic control valve 4 can rapidly reach the opening oil pressure of the hydraulic control valve 4 to open the hydraulic control valve 4, the brake oil output by the first master cylinder 2 enters the pedal simulator 3 through the hydraulic control valve 4, and the pedal simulator 3 provides a pedal feeling.

According to the brake stroke signal of the pedal stroke detection unit, the hydraulic drive unit which controls the brake wheel cylinder 10 to provide brake oil provides signal oil for the control end of the hydraulic control valve 4, and after the hydraulic control valve 4 is opened, the hydraulic control valve 4 allows the brake oil in the first main cylinder 2 to flow to the pedal simulator 3. Before the hydraulic control valve 4 is opened, a driver does not feel pedal feeling; the pedal simulator 3 provides a real pedal feel after the pilot operated valve 4 is opened to improve the reliability of the simulator brake system.

The hydraulic drive unit provides signal oil for the control end of the hydraulic control valve 4 to realize the on-off control of the hydraulic control valve 4, the hydraulic control valve 4 is not required to be electrified, and the problem that the coil generates heat due to the fact that the simulator control valve is electrified for a long time when the simulator control valve is adopted to communicate the first main cylinder with the pedal simulator is solved.

The hydraulic control valve 4 can be a two-position two-way reversing valve, a two-position three-way reversing valve, a hydraulic control one-way valve and the like, the simulator braking system has a high requirement on the flow capacity of the first oil path 13, the flow capacities of the reversing valves such as the two-position two-way reversing valve and the two-position three-way reversing valve are difficult to meet, although a two-stage valve structure formed by integrating the two-position two-way reversing valve or the two-position three-way reversing valve and the one-way valve can be adopted, the two-stage valve structure has the problems of complex structure, high manufacturing cost and difficulty in guaranteeing reliability, the hydraulic control valve 4 preferably adopts the hydraulic control one-way valve, the manufacturing process of the hydraulic control one-way valve is mature, the flow capacity is high, the structure is simple, the cost is low, the flow capacity between the first main cylinder 2 and the pedal simulator 3 can be effectively guaranteed to meet the requirement, and the cost is reduced.

Further, the simulator brake system further includes a simulator control valve 5, the simulator control valve 5 is disposed on the control oil path 15, and the simulator control valve 5 is configured to connect or disconnect the control oil path 15. When the ABS or ESC function is started, the oil pressure of the brake wheel cylinder 10 has large fluctuation, especially when the oil pressure of the brake wheel cylinder 10 fluctuates up and down near the starting oil pressure of the hydraulic control one-way valve, the hydraulic control one-way valve is frequently opened and closed, so that the stability of the hydraulic control one-way valve is poor, by arranging the simulator control valve 5, when the ABS or ESC function is started, the control oil way 15 can be disconnected through the simulator control valve 5, the pedal simulator 3 and the brake wheel cylinder 10 are completely decoupled, and the influence of the oil pressure fluctuation of the brake wheel cylinder 10 on the opening and closing state of the hydraulic control valve 4 is avoided.

The ABS is a brake anti-lock braking system and is used for automatically controlling the braking force of a brake when a vehicle brakes, so that wheels are not locked and are in a rolling and sliding state, and the maximum adhesive force between the wheels and the ground is ensured. Without an ABS vehicle, when the vehicle is subjected to emergency braking in case of emergency, tire locking easily occurs, namely, a steering wheel cannot rotate, and the danger coefficient of the vehicle is high. The structure of the brake anti-lock system is prior art and will not be described in detail here.

ESC is electronic car stability control system and driving safety complementary system, and the vehicle is very unstable when fast turning or changing lanes, through wheel brake or control engine torque, compensates the stability of vehicle. When the vehicle is in an extremely unstable state, the ESC function is automatically started, and when the vehicle runs normally, the ESC does not work. The structure of the electronic vehicle stability control system and the driving safety supplement system is prior art and will not be described in detail herein.

In this embodiment, the simulator control valve 5 is a normally open solenoid valve, and the simulator control valve 5 is electrically connected to the electronic control unit. Specifically, a two-position two-way valve, a two-position three-way valve, or the like may be employed. When the simulator control valve 5 is in a power-off state, the control oil way 15 is in a communication state; when the simulator control valve 5 is in the energized state, the control oil passage 15 is in the disconnected state.

Because the control oil way 15 is in a communicated state for a long time, the simulator control valve 5 adopts a normally open electromagnetic valve, when the simulator control valve 5 is in a power-off state during conventional braking, the brake oil provided by the hydraulic drive unit can directly enter the control end of the hydraulic control valve 4 through the simulator control valve 5, the simulator control valve 5 is not required to be electrified, and the simulator control valve 5 can be prevented from being electrified and heated for a long time to reduce the reliability of the simulator control valve 5; when the ABS or ESC function is started, the control simulator control valve 5 is electrified to disconnect the control oil path 15, so that the pedal simulator 3 and the brake wheel cylinder 10 are completely decoupled, and the oil pressure fluctuation of the brake wheel cylinder 10 is prevented from influencing the opening and closing state of the hydraulic control valve 4.

Further, the simulator brake system further includes a wheel cylinder isolation valve 9, and the hydraulic drive unit is communicated with or disconnected from a brake wheel cylinder 10 through the wheel cylinder isolation valve 9. Specifically, the wheel cylinder isolation valve 9 is provided on the second oil passage 14, and is provided downstream of the position where the control oil passage 15 communicates with the second oil passage 14. In this embodiment, the wheel cylinder isolation valve 9 is a normally closed electromagnetic valve, and the wheel cylinder isolation valve 9 is electrically connected to the electronic control unit. When the wheel cylinder isolation valve 9 is in a power-off state, the second oil way 14 is in a disconnected state; when the wheel cylinder isolation valve 9 is in the energized state, the second oil passage 14 is in the communication state. Specifically, the wheel cylinder isolation valve 9 may be a two-position two-way solenoid valve, a two-position three-way solenoid valve, or the like.

When the electronic control unit controls the hydraulic drive unit to act according to the braking force target request signal, the wheel cylinder isolation valve 9 is electrified, and the braking oil provided by the second master cylinder 8 enters the brake wheel cylinder 10 through the second oil path 14.

The conventional braking process by adopting the simulator braking system comprises the following steps: a driver inputs a braking request by stepping on the brake pedal 1, the pedal stroke detection unit senses the position change of the brake pedal 1 in real time to form a braking stroke signal, the electronic control unit receives the braking stroke signal, converts the braking stroke signal into a braking force target request signal and controls the hydraulic drive unit to act according to the braking force target request signal, the hydraulic drive unit transmits braking oil to a brake wheel cylinder 10 through a second oil path 14, preloads the brake wheel cylinder 10, and enables the braking force provided by a brake caliper to reach the braking force target request value corresponding to the braking force target request signal, thereby realizing vehicle braking; because simulator control valve 5 is normally open solenoid valve, the partial brake oil that hydraulic drive unit provided will pass through simulator control valve 5 as signal oil and get into the control end of hydraulic control valve 4, makes hydraulic control valve 4 open, and after hydraulic control valve 4 opened, the brake oil that first master cylinder 2 provided will pass through hydraulic control valve 4 and get into pedal simulator 3, provides the footboard through pedal simulator 3 and feels.

The simulator braking system further comprises a standby braking unit, and the standby braking unit is used for entering a pure mechanical standby state when the simulator braking system encounters serious electrical faults, so that the brake oil of the first master cylinder 2 can enter the brake wheel cylinder 10 through the standby braking unit, the brake caliper generates braking force, and the vehicle braking safety is guaranteed. The structure of the backup brake unit is prior art and will not be described in detail herein.

Specifically, when the simulator brake system encounters a serious electrical fault, the simulator control valve 5 is powered off to enable the control oil passage 15 to be communicated, and the wheel cylinder isolation valve 9 is powered off to enable the second oil passage 14 to be disconnected, so that the brake wheel cylinder 10 is decoupled from the pedal simulator 3; meanwhile, the motor 6 is powered off, the second main cylinder 8 returns to the initial position due to residual oil pressure in the second main cylinder and the restoring force of a spring in the second main cylinder, so that the control ends of the second main cylinder 8 and the hydraulic control valve 4 are decompressed, the hydraulic control valve 4 is closed, the first oil path 13 connecting the first main cylinder 2 and the pedal simulator 3 is disconnected, and the brake oil of the first main cylinder 2 enters the brake wheel cylinder 10 through the standby brake unit so as to be braked by the brake caliper.

It should be noted that although the brake pedal 1 is continuously pressed, the hydraulic control valve 4 is closed, and the pedal simulator 3 cannot continuously provide pedal feeling, in the process of releasing the brake pedal 1, once the oil pressure at the end where the hydraulic control valve 4 is communicated with the brake master cylinder 2 is not greater than the oil pressure at the end where the hydraulic control valve 4 is communicated with the pedal simulator 3, the hydraulic control valve 4 can still be opened, so that the pedal simulator 3 and the brake pedal 1 are reset, and the pedal simulator 3 and the brake wheel cylinder 10 are decoupled.

The present embodiment further provides a control method of the simulator brake system, fig. 2 is a flowchart of the control method of the simulator brake system provided in the present embodiment, and the following describes the control method of the simulator brake system in detail with reference to fig. 2.

And S11, obtaining the brake stroke signal collected by the pedal stroke detection unit.

And S12, judging whether the brake pedal 1 reaches the preset position according to the brake travel signal, if so, executing S13, and if not, continuously judging whether the brake pedal 1 reaches the preset position.

When the brake pedal 1 reaches a preset position, the hydraulic drive unit provides brake oil for the brake wheel cylinder 10 to preload the brake wheel cylinder 10, when the brake wheel cylinder 10 is preloaded, the brake caliper connected with the brake wheel cylinder 10 provides braking force, and the pedal simulator 3 needs to provide pedal feeling synchronous with the braking force of the brake caliper. The above-mentioned preset position is defined in order to avoid that the pilot operated valve 4 opens too late to cause a delay in the pedal feel provided by the pedal simulator 3. Specifically, the position of the brake pedal 1 when the preloading of the brake wheel cylinder 10 is finished is a designated position, when the brake pedal 1 is located at a preset position, the brake pedal 1 does not exceed the designated position, when the preloading of the brake wheel cylinder 10 is finished, the hydraulic control valve 4 is opened, the brake oil provided by the first main cylinder 2 can enter the pedal simulator 3 through the hydraulic control valve 4, the pedal simulator 3 provides a pedal feeling synchronous with the braking force provided by the brake caliper, and the safety of a brake system of the simulator is improved. The pre-load of the wheel cylinder 10 refers to a process of supplying brake oil to the wheel cylinder 10 by the hydraulic drive unit when the brake caliper does not start to supply braking force.

In addition, the brake wheel cylinder 10 is preloaded to be finished, the brake caliper starts to provide braking force, and at this time, the oil pressure in the brake wheel cylinder 10 is far larger than the opening oil pressure of the pilot-controlled valve 4, so that frequent opening of the pilot-controlled valve 4 caused by fluctuation of the oil pressure of the brake wheel cylinder 10 due to the change of the force of the driver for pressing the brake pedal 1 can be effectively avoided, and the reliability of the pilot-controlled valve 4 is improved.

As for how to judge whether the brake pedal 1 reaches the preset position or not based on the brake stroke signal of the pedal stroke detecting unit, and the pilot operated valve 4 is opened before preloading the brake wheel cylinder 10, the structure that the pedal stroke detecting unit can adopt is detailed in the foregoing, and will not be described repeatedly. Taking the example that the pedal stroke detection unit detects the displacement change of the piston of the first master cylinder 2, when the displacement of the piston of the first master cylinder 2 reaches the preset displacement, it indicates that the pedal simulator 3 needs to be opened, and at this time, the hydraulic control driving unit is controlled to provide signal oil for the control end of the hydraulic control valve 4 to open the hydraulic control valve 4. By specifically limiting the above-described preset displacement and the opening oil pressure of the pilot valve 4, it is achieved that the pilot valve 4 is already opened before preloading of the brake cylinder 10.

And S13, the electronic control unit controls the wheel cylinder isolation valve 9 to be electrified, and simultaneously controls the motor 6 to work to enable the second master cylinder 8 to provide brake oil for the brake wheel cylinder 10 so as to preload the brake wheel cylinder 10, and part of the brake oil is used as signal oil to be sent to the control end of the pilot-controlled valve 4 to enable the pilot-controlled valve 4 to be opened.

And S14, judging whether the ABS or ESC function is started, if so, executing S15, and if not, returning to S14.

And S15, the electric control unit controls the simulator to control the power-on of the valve 5.

In steps S11 to S15, whether or not the brake needs to be released is checked in real time based on the brake stroke signal, and when the brake pedal 1 starts to return, the brake needs to be released is checked, the electric control unit controls the motor 6 to stop operating, the piston of the second master cylinder 8 is gradually returned, the wheel cylinder 10 is gradually returned, and the brake caliper gradually releases the brake. Meanwhile, the simulator control valve 5 is controlled to lose power to enable the control oil way 15 to be in a communicated state, and signal oil at the control end of the hydraulic control valve 4 gradually flows back to the second main cylinder 8 through the simulator control valve 5, so that the control end of the hydraulic control valve 4 is gradually decompressed; meanwhile, as the brake pedal 1 is reset, the pedal simulator 3 uses its internal reset spring to return the brake oil in the pedal simulator 3 to the first master cylinder 2 through the hydraulic control valve 4.

Adopt the simulator braking system that this embodiment provided, only need adopt the conventional liquid accuse check valve of prior art can realize providing the footboard by footboard simulator 3 and feel, and carry out the pressure release to footboard simulator 3, the simple structure of liquid accuse check valve, it is with low costs.

Example two

Fig. 3 is a schematic diagram of the simulator brake system provided in the present embodiment. As shown in fig. 3, the present embodiment provides a simulator braking system, which includes a brake pedal 1 and a first main cylinder 2, wherein the brake pedal 1 is connected to the first main cylinder 2, specifically, the first main cylinder 2 includes a cylinder body and a piston slidably disposed in the cylinder body, one end of the brake pedal 1 is hinged to an input end of a pedal transmission assembly, and the other end is used for stepping; the output end of the pedal transmission assembly is hinged with the piston of the first main cylinder 2, the brake pedal 1 is stepped, the brake pedal 1 drives the piston of the first main cylinder 2 to move in the cylinder body through the pedal transmission assembly, and therefore brake oil in the first main cylinder 2 flows out to a valve, a structural member and the like connected with the brake oil. The pedal transmission assembly may be a pedal rod, or may be other structures capable of realizing power transmission between the brake pedal 1 and the piston of the first master cylinder 2, and details thereof will not be described herein.

The simulator braking system further comprises a brake wheel cylinder 10, a hydraulic driving unit and an electronic control unit, wherein the electronic control unit is electrically connected with the hydraulic driving unit, and the hydraulic driving unit can receive a control command of the electronic control unit to provide brake oil for the brake wheel cylinder 10, so that the brake wheel cylinder 10 provides brake oil for the brake caliper, and the brake caliper performs a braking action.

The electric control unit is electrically connected with a pedal stroke detection unit, the pedal stroke detection unit senses the position change of the brake pedal 1 to form a brake stroke signal, and the electric control unit can receive the brake stroke signal of the pedal stroke detection unit. The pedal stroke detecting means may be a displacement sensor for detecting a displacement of the brake pedal 1, an angle sensor for detecting a rotation angle of the brake pedal 1 about its rotation axis, or the like, and may be a displacement sensor for detecting a piston displacement of the first master cylinder 2, a pressure sensor for detecting an output hydraulic pressure of the brake oil output from the first master cylinder 2, or the like, which are not illustrated herein.

When a driver steps on or releases the brake pedal 1, the pedal stroke detection unit can form a brake stroke signal to show whether the driver has the operation of braking or braking release, and the electronic control unit can receive the brake stroke signal of the pedal stroke detection unit, convert the brake stroke signal into a target braking force request signal, and control the hydraulic drive unit to operate according to the target braking force request signal so as to provide brake oil for the brake wheel cylinder 10 and enable the brake wheel cylinder 10 to operate.

It should be noted that the electronic control unit may be a centralized or distributed controller, for example, it may be a single-chip microcomputer or may be formed by a plurality of distributed single-chip microcomputers, and the single-chip microcomputers may run a control program and perform signal transmission, so as to control each component to implement its function.

In order to realize that the hydraulic driving unit supplies brake oil to the brake wheel cylinders 10, the hydraulic driving unit comprises the motor 6 and the second main cylinder 8, wherein the motor 6 is electrically connected with the electronic control unit, the output shaft of the motor 6 is in transmission connection with the pistons of the second main cylinder 8, and the second main cylinder 8 supplies brake oil to the brake wheel cylinders 10 through the second oil path 14 so as to actuate the brake calipers. In other embodiments, the hydraulic driving unit may also use a motor to drive a hydraulic pump to work, and the hydraulic pump supplies brake oil to the brake wheel cylinder 10.

In this embodiment, the motor 6 is a motor capable of rotating, an output shaft of the motor 6 is connected with the piston of the second master cylinder 8 through a transmission member 7, and the rotation of the output shaft of the motor 6 is converted into the movement of the piston of the second master cylinder 8 by using the transmission member 7; the transmission member 7 is a rack and pinion structure, a nut and screw structure, or a worm and gear structure, and will not be described in detail. In other embodiments, the motor 6 may also be a linear motor, and an output shaft of the motor 6 may be directly connected to the piston of the second master cylinder 8, and the linear motor directly controls the piston of the second master cylinder 8.

Further, the motor 6 is a servo motor, and the second master cylinder 8 is a servo cylinder, so that control accuracy is improved. It should be noted that the motor 6 is not limited to a servo motor, and a general motor may be used.

The simulator braking system further comprises a hydraulic control valve 4 and a pedal simulator 3, wherein the hydraulic control valve 4 is connected between the first main cylinder 2 and the pedal simulator 3, and the hydraulic driving unit can provide signal oil for a control end of the hydraulic control valve 4 through a control oil path 15, so that the hydraulic control valve 4 allows the brake oil in the first main cylinder 2 to flow to the pedal simulator 3. Specifically, the first master cylinder 2 is communicated with the pedal simulator 3 through a first oil path 13, the hydraulic control valve 4 is disposed on the first oil path 13, and the second oil path 14 is communicated with a control end of the hydraulic control valve 4 through a control oil path 15 to provide signal oil to the control end to open the hydraulic control valve 4.

Considering that the oil pressure of the brake wheel cylinder 10 is usually greater than the oil pressure of the first master cylinder 2, even several times the oil pressure of the first master cylinder 2 during braking, when the hydraulic drive unit is operated by selecting the hydraulic control valve 4 with a proper opening oil pressure, the brake oil provided by the hydraulic drive unit enters the control end of the hydraulic control valve 4 through the control oil path 15, the oil pressure at the control end of the hydraulic control valve 4 can rapidly reach the opening oil pressure of the hydraulic control valve 4 to open the hydraulic control valve 4, the brake oil output by the first master cylinder 2 enters the pedal simulator 3 through the hydraulic control valve 4, and the pedal simulator 3 provides a pedal feeling.

According to the brake stroke signal of the pedal stroke detection unit, the hydraulic drive unit which controls the brake wheel cylinder 10 to provide brake oil provides signal oil for the control end of the hydraulic control valve 4, and after the hydraulic control valve 4 is opened, the hydraulic control valve 4 allows the brake oil in the first main cylinder 2 to flow to the pedal simulator 3. Before the hydraulic control valve 4 is opened, a driver does not feel pedal feeling; the pedal simulator 3 provides a real pedal feel after the pilot operated valve 4 is opened to improve the reliability of the simulator brake system.

The hydraulic drive unit provides signal oil for the control end of the hydraulic control valve 4 to realize the on-off control of the hydraulic control valve 4, the hydraulic control valve 4 is not required to be electrified, and the problem that the coil generates heat due to the fact that the simulator control valve is electrified for a long time when the simulator control valve is adopted to communicate the first main cylinder with the pedal simulator is solved.

The hydraulic control valve 4 can be a two-position two-way reversing valve, a two-position three-way reversing valve, a hydraulic control one-way valve and the like, the simulator braking system has a high requirement on the flow capacity of the first oil path 13, the flow capacities of the reversing valves such as the two-position two-way reversing valve and the two-position three-way reversing valve are difficult to meet, although a two-stage valve structure formed by integrating the two-position two-way reversing valve or the two-position three-way reversing valve and the one-way valve can be adopted, the two-stage valve structure has the problems of complex structure, high manufacturing cost and difficulty in guaranteeing reliability, the hydraulic control valve 4 preferably adopts the hydraulic control one-way valve, the manufacturing process of the hydraulic control one-way valve is mature, the flow capacity is high, the structure is simple, the cost is low, the flow capacity between the first main cylinder 2 and the pedal simulator 3 can be effectively guaranteed to meet the requirement, and the cost is reduced.

Further, the simulator brake system further comprises an energy storage unit and a simulator control valve 5, the simulator control valve 5 is arranged on the control oil path 15, and the simulator control valve 5 is used for enabling the control oil path 15 to be communicated or disconnected; the energy storage unit is communicated with the control oil path 15 and is positioned between the simulator control valve 5 and the control end. The energy storage unit is preferably an energy accumulator 11, or other structures with energy storage function, which are not listed here.

In this embodiment, the simulator control valve 5 is a normally closed solenoid valve, and the simulator control valve 5 is electrically connected to the electronic control unit. When the simulator control valve 5 is in a power-off state, the control oil way 15 is in a disconnected state; when the simulator control valve 5 is in the energized state, the control oil passage 15 is in the communicating state.

During normal braking, the control simulator control valve 5 is powered on, the hydraulic drive unit provides pilot oil for the control end of the hydraulic control valve 4, after the hydraulic control valve 4 is opened, part of the pilot oil enters the energy accumulator 11, when the oil pressure in the brake cylinder 10 reaches the target oil pressure, the control simulator control valve 5 is powered off, the control oil way 15 is disconnected, and the hydraulic control valve 4 is kept in an opening state by using the energy stored in the energy accumulator 11. Because the simulator control valve 5 is a normally closed electromagnetic valve, the simulator control valve 5 only needs to be electrified before the oil pressure of the brake wheel cylinder 10 reaches the target oil pressure during normal braking, the opening time of the simulator control valve 5 is short, and the problem that the simulator control valve 5 is electrified and heated for a long time to influence the stability and reliability of the simulator control valve 5 can be avoided.

In addition, when the ABS or ESC function is turned on or oil leaks, the oil pressure of the brake cylinder 10 fluctuates greatly, especially when the oil pressure of the brake cylinder 10 fluctuates up and down near the opening oil pressure of the pilot-operated check valve, the pilot-operated check valve will frequently open and close, so that the stability of the pilot-operated check valve is poor, by setting the simulator control valve 5, when the oil pressure at the control end reaches the target oil pressure, the control oil path 15 is disconnected by the simulator control valve 5, the pedal simulator 3 and the brake cylinder 10 are completely decoupled, and the switching state of the pilot-operated check valve 4 is prevented from being influenced when the oil pressure of the brake cylinder 10 fluctuates due to the turning on of the ABS or ESC function or oil leakage.

The ABS is a brake anti-lock braking system and is used for automatically controlling the braking force of a brake when a vehicle brakes, so that wheels are not locked and are in a rolling and sliding state, and the maximum adhesive force between the wheels and the ground is ensured. Without an ABS vehicle, when the vehicle is subjected to emergency braking in case of emergency, tire locking easily occurs, namely, a steering wheel cannot rotate, and the danger coefficient of the vehicle is high. The structure of the brake anti-lock system is prior art and will not be described in detail here.

ESC is electronic car stability control system and driving safety complementary system, and the vehicle is very unstable when fast turning or changing lanes, through wheel brake or control engine torque, compensates the stability of vehicle. When the vehicle is in an extremely unstable state, the ESC function is automatically started, and when the vehicle runs normally, the ESC does not work. The structure of the electronic vehicle stability control system and the driving safety supplement system is prior art and will not be described in detail herein.

Further, the simulator brake system further includes a wheel cylinder isolation valve 9, and the hydraulic drive unit is communicated with or disconnected from a brake wheel cylinder 10 through the wheel cylinder isolation valve 9. Specifically, the wheel cylinder isolation valve 9 is provided on the second oil passage 14, and is provided downstream of the position where the control oil passage 15 communicates with the second oil passage 14. In this embodiment, the wheel cylinder isolation valve 9 is a normally closed electromagnetic valve, and the wheel cylinder isolation valve 9 is electrically connected to the electronic control unit. When the wheel cylinder isolation valve 9 is in a power-off state, the second oil way 14 is in a disconnected state; when the wheel cylinder isolation valve 9 is in the energized state, the second oil passage 14 is in the communication state. Specifically, the wheel cylinder isolation valve 9 may be a two-position two-way solenoid valve, a two-position three-way solenoid valve, or the like.

When the electronic control unit controls the hydraulic drive unit to act according to the braking force target request signal, the wheel cylinder isolation valve 9 is electrified, and the braking oil provided by the second master cylinder 8 enters the wheel cylinder 10 through the second oil path 14 to preload the wheel cylinder 10.

The conventional braking process by adopting the simulator braking system comprises the following steps: a driver inputs a braking request by stepping on the brake pedal 1, the pedal stroke detection unit senses the position change of the brake pedal 1 in real time to form a braking stroke signal, the electronic control unit receives the braking stroke signal, controls the simulator control valve 5 to be electrified, simultaneously converts the braking stroke signal into a braking force target request signal, controls the hydraulic drive unit to act according to the braking force target request signal, and transmits the braking oil to the brake wheel cylinder 10 through the second oil way 14, and preloads the brake wheel cylinder 10 to achieve a braking force target request value corresponding to the braking force target request signal, so that vehicle braking is realized; because simulator control valve 5 is normally open solenoid valve, the partial brake oil that hydraulic drive unit provided will pass through simulator control valve 5 as signal oil and get into the control end of hydraulic control valve 4, makes hydraulic control valve 4 open, and after hydraulic control valve 4 opened, the brake oil that first master cylinder 2 provided will pass through hydraulic control valve 4 and get into pedal simulator 3, provides the footboard through pedal simulator 3 and feels.

Further, the above-described simulator brake system further includes a simulator pressure relief control valve 12, the pilot oil passage 15 and the hydraulic oil tank can be connected or disconnected by the simulator pressure relief control valve 12, and a communication position of the simulator pressure relief control valve 12 and the pilot oil passage 15 is located between the simulator control valve 5 and the pilot end of the pilot operated valve 4.

When the control end of the hydraulic control valve 4 needs to be decompressed, the simulator pressure relief control valve 12 is controlled to be powered off to enable the control oil path 15 to be communicated with the hydraulic oil tank, and the signal oil at the control end and the signal oil in the energy accumulator 11 flow into the hydraulic oil tank through the simulator pressure relief control valve 12, so that the control end of the hydraulic control valve 4 is decompressed quickly.

Compared with the first embodiment, the present embodiment adopts the normally closed electromagnetic valve as the simulator control valve 5, and cooperates with the simulator pressure relief control valve 12, so as to realize the rapid pressure relief of the control end of the hydraulic control valve 4.

In this embodiment, the simulator pressure relief control valve 12 is a normally open solenoid valve, and during normal braking, the simulator pressure relief control valve 12 is in an energized state, so that the control oil path 15 is disconnected from the hydraulic oil tank; when the simulator pressure relief control valve 12 is in a power-off state, the control oil path 15 is communicated with the hydraulic oil tank, so that the hydraulic control valve 4 is closed, and the first master cylinder 2 is disconnected from the pedal simulator 3. When the simulator brake system encounters serious electrical fault, the simulator pressure relief control valve 12 loses power to relieve the pressure of the control end of the hydraulic control valve 4, so that the hydraulic control valve 4 is closed.

The simulator braking system further comprises a standby braking unit, and the standby braking unit is used for entering a pure mechanical standby state when the simulator braking system encounters serious electrical faults, so that the brake oil of the first master cylinder 2 can enter the brake wheel cylinder 10 through the standby braking unit, the brake caliper generates braking force, and the vehicle braking safety is guaranteed. The structure of the backup brake unit is prior art and will not be described in detail herein.

Specifically, when the simulator brake system encounters a serious electrical fault, the simulator control valve 5 is powered off to disconnect the control oil passage 15, and the wheel cylinder isolation valve 9 is powered off to disconnect the second oil passage 14, so that the brake wheel cylinder 10 is decoupled from the pedal simulator 3; meanwhile, the simulator pressure relief control valve 12 is powered off to enable the control oil path 15 to be communicated with the hydraulic oil tank, the control end of the hydraulic control valve 4 is relieved, the hydraulic control valve 4 is closed, the first main cylinder 2 and the pedal simulator 3 are disconnected, and brake oil of the first main cylinder 2 enters the brake wheel cylinder 10 through the standby brake unit to be braked by the brake caliper.

It should be noted that, although the brake pedal 1 is continuously depressed, the pedal simulator 3 cannot continuously provide the pedal feeling because the hydraulic control valve 4 is closed, but in the process of releasing the brake pedal 1, once the oil pressure at the end where the hydraulic control valve 4 is communicated with the master cylinder 2 is not greater than the oil pressure at the end where the hydraulic control valve 4 is communicated with the pedal simulator 3, the hydraulic control valve 4 can still be opened, so that the pedal simulator 3 and the brake pedal 1 can be reset.

The present embodiment further provides a control method of the simulator brake system, fig. 4 is a flowchart of the control method of the simulator brake system provided in the present embodiment, and the following describes the control method of the simulator brake system in detail with reference to fig. 4.

And S21, obtaining the brake stroke signal collected by the pedal stroke detection unit.

And S22, judging whether the brake pedal 1 reaches the preset position according to the brake travel signal, if so, executing S23, and if not, continuously judging whether the brake pedal 1 reaches the preset position.

When the brake pedal 1 reaches a preset position, the hydraulic drive unit provides brake oil for the brake wheel cylinder 10 to preload the brake wheel cylinder 10, when the brake wheel cylinder 10 is preloaded, the brake caliper connected with the brake wheel cylinder 10 provides braking force, and the pedal simulator 3 needs to provide pedal feeling synchronous with the braking force of the brake caliper. The above-mentioned preset position is defined in order to avoid that the pilot operated valve 4 opens too late to cause a delay in the pedal feel provided by the pedal simulator 3. Specifically, the position of the brake pedal 1 when the preloading of the brake wheel cylinder 10 is finished is a designated position, when the brake pedal 1 is located at a preset position, the brake pedal 1 does not exceed the designated position, when the preloading of the brake wheel cylinder 10 is finished, the hydraulic control valve 4 is opened, the brake oil provided by the first main cylinder 2 can enter the pedal simulator 3 through the hydraulic control valve 4, the pedal simulator 3 provides a pedal feeling synchronous with the braking force provided by the brake caliper, and the safety of a brake system of the simulator is improved.

In addition, after the brake wheel cylinder 10 is preloaded, the brake caliper starts to provide braking force, and at this time, the oil pressure in the brake wheel cylinder 10 is far greater than the opening oil pressure of the pilot valve 4, so that even if the oil pressure of the brake wheel cylinder 10 still does not reach the target oil pressure, the frequent opening of the pilot valve 4 caused by the fluctuation of the oil pressure of the brake wheel cylinder 10 due to the variation of the force with which the driver depresses the brake pedal 1 can be effectively avoided, and the reliability of the pilot valve 4 is improved.

As for how to judge whether the brake pedal 1 reaches the preset position or not based on the brake stroke signal of the pedal stroke detecting unit, and the pilot operated valve 4 is opened before preloading the brake wheel cylinder 10, the structure that the pedal stroke detecting unit can adopt is detailed in the foregoing, and will not be described repeatedly. Taking the example that the pedal stroke detection unit detects the displacement change of the piston of the first master cylinder 2, when the displacement of the piston of the first master cylinder 2 reaches the preset displacement, it indicates that the pedal simulator 3 needs to be opened, and at this time, the hydraulic control driving unit is controlled to provide signal oil for the control end of the hydraulic control valve 4 to open the hydraulic control valve 4. By specifically limiting the preset displacement and the opening oil pressure of the pilot control valve 4, it is achieved that the pilot control valve 4 is already opened before the brake wheel cylinder 10 is preloaded.

And S23, the electric control unit controls the wheel cylinder isolation valve 9, the simulator control valve 5 and the simulator pressure relief control valve 12 to be powered on, and simultaneously controls the motor 6 to work to enable the second master cylinder 8 to provide brake oil for the brake wheel cylinder 10 to preload the brake wheel cylinder 10, and sends part of the brake oil as signal oil to the control end of the pilot-controlled valve 4 to enable the pilot-controlled valve 4 to be opened.

S24, it is determined whether the hydraulic pressure in the brake cylinder 10 has reached the target hydraulic pressure, if so, S25 is executed, and if not, it is continuously determined whether the hydraulic pressure in the brake cylinder 10 has reached the target hydraulic pressure.

And S25, the electric control unit controls the simulator to control the power loss of the valve 5.

In steps S21 to S25, whether or not the brake needs to be released is checked in real time based on the brake stroke signal, and when the brake pedal 1 starts to return, the brake needs to be released is checked, the electric control unit controls the motor 6 to stop operating, the piston of the second master cylinder 8 is gradually returned, the wheel cylinder 10 is gradually returned, and the brake caliper gradually releases the brake. Meanwhile, the electric control unit controls the simulator control valve 5 and the simulator pressure relief control valve 12 to lose power so as to quickly relieve the pressure of the energy accumulator 11 and the control end of the hydraulic control valve 4, and the pedal simulator 3 utilizes the internal return spring thereof to enable the brake oil in the pedal simulator 3 to return to the first main cylinder 2 through the hydraulic control valve 4.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.