CN211617660U - Brake-by-wire system capable of simulating pedal feel - Google Patents

Abstract

The utility model relates to a brake-by-wire system capable of simulating pedal feeling. The specific structure comprises a brake master cylinder, a master cylinder driving device, a brake wheel cylinder, a liquid storage tank, a secondary master cylinder, a pedal push rod, and a pedal feeling simulation system. The braking system of the utility model includes three braking functions: conventional braking, active braking and failure backup, and the conventional braking includes three processes of boosting, maintaining pressure and decompressing; the utility model realizes The decoupling of the brake pedal and the brake wheel cylinder is realized, and various complex pedal reaction forces can be simulated by adjusting the reversing valve pedal feeling simulator to match the drivers of different driving styles; the pedal travel sensor can realize the driver control. The identification of the moving intention; the linear pressure regulating valve can realize the precise control of the brake wheel cylinder pressure.

Description

A brake-by-wire system that simulates pedal feel

technical field

The utility model relates to a wire-controlled braking system, in particular to a wire-controlled braking system which can simulate pedal feeling.

Background technique

The birth and development of automobiles have brought convenience to human's daily travel and made the world economy more dynamic. At the same time, the development of the automobile industry has also brought some adverse effects on the environment, traffic, travel safety, energy, etc. Therefore, "safety, energy saving, and environmental protection" has become the theme of the current development of the automobile industry, which makes the car's initiative Safety technology, new energy technology and intelligent technology have developed rapidly. Among them, the braking system is closely related to the driving safety of the car, and has always been a hot spot of research and development.

The traditional braking system technology is relatively mature, but with the development of automobile electrification and intelligent technology, the traditional braking system is limited by its structure and working principle, and it is difficult to realize man-machine decoupling, active and rapid pressure build-up, single braking system. Wheel pressure precise control, etc. For example, the traditional vacuum-assisted braking system relies on the engine to provide a vacuum source, but the electric vehicle cancels the engine, and the traditional braking system technology is challenged.

The brake-by-wire system is developed from the combination of the wire-controlled technology and the automobile braking system. It realizes the complete decoupling of the pedal force, that is, the direct connection between the brake pedal and the brake wheel cylinder is cancelled, and the driver's braking intention is eliminated. It is no longer mechanically transmitted to the braking system but electronically, which requires the design of a pedal feel simulator to simulate the driver's foot feel.

The more typical brake-by-wire systems mainly include electronic hydraulic brake system (EHB) and electromechanical brake system (EMB). The EHB braking system cancels the vacuum booster and uses a high-pressure accumulator as the system pressure source. The structure is simple and compact, the brake pedal is decoupled from the brake wheel cylinder, and the braking force of each wheel can be individually controlled, which is easy to recover energy. However, most of its pedal feel simulators are passive, the pedal feel is difficult to adjust, the hydraulic pipeline is complex, the braking efficiency is reduced, and it is difficult to meet the braking demand when the system circuit fails. The EMB braking system mostly adopts the planetary gear mechanism to decelerate and increase the torque, and convert the rotation into translation through the ball screw mechanism, so that the brake caliper body clamps the brake disc to complete the braking. Although the EMB braking system has the advantages of no brake pipeline and high braking efficiency, its cost is high, the working environment temperature is high, and the reliability requirements are too high, making it difficult to achieve lightweight design and mass production.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the utility model provides a brake-by-wire system capable of simulating pedal feeling. The specific structure includes a brake master cylinder, a master cylinder driving device, a brake wheel cylinder, a liquid storage tank, a secondary master cylinder, a pedal Push rod, pedal feeling simulator and electronic control unit ECU, wherein the brake master cylinder includes a master cylinder push rod, a master cylinder piston and a master cylinder return spring, and a master cylinder hydraulic pressure is formed between the master cylinder piston and the cylinder block The master cylinder return spring is set in the master cylinder hydraulic chamber; the master cylinder driving device is connected with the master cylinder push rod, which can push the master cylinder piston to build pressure in the master cylinder hydraulic chamber; the master cylinder hydraulic chamber is connected to the brake through the pipeline The wheel cylinder is connected, and the brake wheel cylinder is connected with the liquid storage tank through a pipeline; a first piston and a second piston are assembled in the secondary master cylinder in sequence, and the first piston, the second piston and the bottom of the cylinder form a first piston in turn. The hydraulic chamber and the second hydraulic chamber, the first hydraulic chamber and the second hydraulic chamber are provided with a return spring, the brake pedal is connected with the pedal push rod, and the pedal push rod passes through the front end of the secondary master cylinder and is connected with the first piston, the secondary The first hydraulic chamber of the primary master cylinder is connected to the pedal feel simulator through pipelines, and the second hydraulic chambers of the secondary master cylinder are respectively connected to the liquid storage tank through pipelines provided with normally closed solenoid valves, The pipeline of the valve is connected with the liquid inlet of the brake wheel cylinder; the electronic control unit ECU is respectively connected with the normally closed solenoid valve and the normally open solenoid valve, and the switch is controlled by the electronic control unit ECU.

A booster valve is arranged on the pipeline between the hydraulic chamber of the master cylinder and the brake wheel cylinder, and a pressure relief valve is arranged on the pipeline between the brake wheel cylinder and the liquid storage tank; the booster valve is a normally open electromagnetic The pressure reducing valve is a normally closed solenoid valve; the boosting valve and the pressure reducing valve are respectively connected with the electronic control unit ECU, and the switch is controlled by the electronic control unit ECU.

The utility model also includes a hydraulic pressure sensor and a pedal stroke sensor, the hydraulic pressure sensor is connected with the liquid outlet of the hydraulic chamber of the master cylinder and the booster valve of each brake wheel cylinder, and measures the hydraulic pressure of the liquid outlet of the hydraulic chamber of the master cylinder. force and the hydraulic pressure of each brake wheel cylinder; the pedal stroke sensor is set on the pedal push rod to detect the displacement data of the pedal push rod; the hydraulic pressure sensor and the pedal stroke sensor are respectively connected with the electronic control unit ECU, and the data Real-time transmission to the electronic control unit ECU.

The pedal feel simulator is divided into a hydraulic cavity and a spring cavity by the simulator piston, and the first hydraulic cavity of the secondary master cylinder is connected with the hydraulic cavity of the pedal feel simulator through a pipeline; the spring cavity is provided with a simulator return spring and a spring cavity. The simulator rubber spring, the simulator return spring is connected between the simulator piston and the bottom of the simulator cylinder, the simulator rubber spring is located inside the simulator return spring, and one end is fixed on the simulator piston.

There is a one-way valve on the pipeline between the first hydraulic chamber of the secondary master cylinder and the pedal feel simulator. When the first piston of the secondary master cylinder is reset, the brake fluid in the hydraulic chamber of the pedal feel simulator flows through. The one-way valve returns to the first hydraulic chamber of the secondary master cylinder; a reversing valve is arranged in parallel with the one-way valve, the reversing valve is a two-position five-way solenoid valve, and the liquid inlet is connected to the secondary main The first hydraulic chamber of the cylinder is connected. When the power is off, the reversing valve is in the left position, so the liquid outlet on the left is normally open. Connect to the hydraulic chamber of the pedal feeling simulator. When the power is turned on, the reversing valve is in the right position, so the right position is out. The liquid port is in a normally closed state and is connected to the liquid storage tank; the reversing valve is connected to the electronic control unit ECU through a line, and the electronic control unit ECU controls the reversing.

The liquid storage tank is respectively connected with the hydraulic chamber of the master cylinder of the master brake cylinder, the first hydraulic chamber of the secondary master cylinder and the liquid inlet of the second hydraulic chamber through pipelines, and is connected to the hydraulic chamber of the master cylinder, the first hydraulic chamber and the second hydraulic chamber. The brake fluid is replenished in the second hydraulic chamber.

The master cylinder driving device includes a rotary motor, a pinion, a large gear, a crank, a connecting rod, and a slider. The output shaft of the rotary motor and the pinion are coaxially arranged, and the large gear and the pinion mesh to form a first-stage deceleration and torque-increasing mechanism. , one end of the crank is fixed in the center of the big gear, and is arranged radially along the big gear, the other end is hinged with the connecting rod, the other end of the connecting rod is hinged with the slider, the slider is connected with the master cylinder push rod of the brake master cylinder, and the slider is set in In the slideway, it translates in the slideway; the rotating motor is connected with the electronic control unit ECU, and the electronic control unit ECU sends a control signal to control its rotation.

There is also a linear pressure regulating valve on the pipeline between the pressure reducing valve of the brake wheel cylinder and the liquid storage tank. The control unit ECU is connected, and the opening degree is controlled and adjusted by the electronic control unit ECU.

The connection between the above-mentioned electronic control unit ECU and each solenoid valve and sensor is all line connection.

The working principle of the present utility model:

1. Conventional braking:

When the driver steps on the brake pedal, the electronic control unit ECU controls the normally closed solenoid valve to energize to open, the normally open solenoid valve to energize to close, the reversing valve is in the left position, and the pedal push rod pushes the first piston of the secondary master cylinder to start moving , and then push the second piston to move through the return spring. Since the normally closed solenoid valve is opened and the normally open solenoid valve is closed, the brake fluid flowing out of the second hydraulic chamber of the secondary master cylinder often closes the solenoid valve and flows back to the storage tank. The brake fluid in the first hydraulic chamber of the primary master cylinder flows into the pedal feel simulator through the reversing valve, and the pressure is not established in the two hydraulic chambers of the secondary master cylinder at this time.

On the other hand, the pedal stroke sensor obtains the pedal displacement information and transmits it to the electronic control unit ECU. After the electronic control unit ECU receives the signal, it calculates the total braking force demand, and then obtains the required hydraulic pressure according to the working characteristics of the master cylinder drive device. The braking force is large, and the electronic control unit ECU sends a control signal to the rotating motor to drive it to rotate. The pressure is built in the hydraulic chamber of the master cylinder, and the brake fluid in the hydraulic chamber of the master cylinder transmits the braking force to each brake wheel cylinder through the hydraulic pipeline.

Conventional braking can be divided into three processes: boosting, maintaining pressure and decompressing.

a) Pressurization process

When the driver steps on the brake pedal, the normally closed solenoid valve is opened, the normally open solenoid valve is closed, and the reversing valve is in the left position; the four pressure boosting valves connected to the brake wheel cylinders are all powered off and opened, and the four pressure reducing valves are turned off. The valves are powered off and closed, and the brake fluid enters the brake wheel cylinder from the master cylinder hydraulic chamber of the brake master cylinder to build pressure.

b) Pressure holding process

When the electronic control unit ECU decides that the brake system needs to maintain pressure, the four pressure boosting valves are all energized and closed, and the four pressure reducing valves are all powered off and closed. At this time, the brake fluid in the brake wheel cylinder and the brake pipeline are are isolated, and the brake pressure in the wheel cylinder remains unchanged.

c) Decompression process

When the driver releases the brake pedal or the control strategy decides that the brake wheel cylinder needs to reduce the pressure, the electronic control unit ECU controls the four pressure-increasing valves to be energized and closed, and the four pressure-reducing valves are energized to open. The brake fluid in the wheel cylinder flows back to the liquid storage tank through the pressure reducing valve pipeline, and the pressure of the brake wheel cylinder is reduced to complete the pressure reduction process.

The pedal feel simulator simulates the process of pedal force:

In the conventional braking process, the pedal is completely decoupled, that is, the driver is only responsible for giving the target braking pressure, and the actual boosting process is completed by the electronic control unit ECU controlling the master cylinder drive device, the brake master cylinder and each solenoid valve. The pedal feel simulator provides the driver with the same pedal feel as the traditional braking system according to the pedal force and pedal displacement curve of the traditional braking system.

During this process, the normally closed solenoid valve is opened, the normally open solenoid valve is closed, and the reversing valve is in the left position. When the driver steps on the brake pedal, the brake fluid in the first hydraulic chamber of the secondary master cylinder flows to the pedal through the reversing valve. Feel the hydraulic chamber of the simulator and act on the simulator piston, pushing the simulator piston towards the bottom of the simulator cylinder. When the pedal displacement is small, the pedal reaction force is generated by the simulator return spring; as the pedal displacement increases, the simulator piston continues to move until the simulator rubber spring contacts the bottom of the simulator cylinder, after which the simulator rubber spring and The simulator return spring is connected in parallel to provide the pedal reaction force. Because the simulator rubber spring has nonlinear elastic force, it can satisfy the nonlinear relationship between the pedal displacement and the pedal force when the pedal displacement is large, and better simulate the driver's pedal feeling.

In order to meet the needs of different types of drivers of the brake pedal feel, it can be achieved through the adjustment of the reversing valve by the electronic control unit ECU. When the reversing valve is switched to the right position, the first hydraulic chamber of the secondary master cylinder is communicated with the liquid storage tank, and the brake fluid in the first hydraulic chamber flows into the liquid storage tank through the reversing valve. At this time, the pedal feeling simulator does not Provides simulated pedal force, which is provided by the return spring in the secondary master cylinder, so that under the same pedal displacement, the generated pedal reaction force becomes smaller. The electronic control unit ECU controls the switching of the reversing valve between the left position and the right position, which realizes the adjustment of the pedal reaction force and can match the drivers with different driving styles.

The control process of brake wheel cylinder pressure:

In the braking system of the present invention, the four pressure-increasing valves and the four pressure-reducing valves are all on-off valves, with only two states: open and closed. A linear pressure regulating valve is connected to the common line returning to the storage tank. The electronic control unit ECU receives the signals from the pedal stroke sensor and the hydraulic pressure sensor. After analysis and decision-making, it controls the opening of the linear pressure regulating valve according to the actual needs of the system, so as to achieve accurate pressure control.

2. Active braking:

Since the brake system pedal of the present invention is completely decoupled, the braking operation can be performed independently of the pedal force of the driver. Taking the emergency braking of a car as an example, when an emergency situation occurs in front of the car, the electronic control unit ECU of the braking system sends a control signal to the rotating motor through decision-making and judgment, and makes the brake master cylinder quickly build up through the master cylinder drive device. pressure. At this time, the four pressure-increasing valves in the braking system are all turned on, and the four pressure-reducing valves are all turned off, and the brake fluid enters the brake wheel cylinder from the brake master cylinder for pressure buildup.

3. Failed backup:

When the electronic control unit ECU of the braking system fails, the normally closed solenoid valve is de-energized and closed, the normally open solenoid valve is de-energized and opened, the reversing valve is in the left position, the four booster valves are all de-energized and opened, and the four decompression valves are de-energized. The valves are de-energized and closed. When the driver depresses the brake pedal, the brake fluid in the first hydraulic chamber of the secondary master cylinder flows into the pedal feel simulator through the reversing valve, and the brake fluid in the second hydraulic chamber of the secondary master cylinder flows to the wheel cylinder, making the The wheels get enough braking force to realize the backup function of failure.

The beneficial effects of the present utility model:

1. The utility model realizes the complete decoupling of the brake pedal and the brake wheel cylinder, combined with the pedal feel simulator with adjustable pedal force, can simulate various complex pedal forces, and match the driving of different driving styles by adjusting the pedal feel. member.

2. The utility model adds a pedal stroke sensor and a hydraulic pressure sensor, which can realize the identification of the driver's braking intention and the precise control of the pressure, and then can precisely adjust the hydraulic pressure of the brake wheel cylinder.

3. The utility model has a failure backup function, that is, when the power is cut off or the electronic control unit ECU fails, the hydraulic braking force can be provided for the brake wheel cylinder through the traditional mechanical pressure building method of the secondary master cylinder.

4. The structure of the utility model meets the requirements of lightweight design, has low requirements for working environment conditions, and has stronger adaptability. In addition to the conventional braking function, it can also integrate functions such as ABS, TCS, ESP, and AEB.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the present utility model;

2 is a schematic structural diagram of the brake master cylinder of the present invention;

3 is a schematic structural diagram of the secondary master cylinder of the present invention;

4 is a schematic structural diagram of the pedal feel simulator of the present invention;

5 is a schematic structural diagram of the master cylinder driving device of the present invention;

1. Brake master cylinder 2, master cylinder drive device 3, brake wheel cylinder 4, fluid storage tank 5, secondary master cylinder 6, pedal push rod 7, pedal feel simulator 8, electronic control unit ECU 9, master cylinder Push rod 10, master cylinder piston 11, master cylinder return spring 12, master cylinder hydraulic chamber 13, booster valve 14, decompression valve 15, first piston 16, second piston 17, first hydraulic chamber 18, second Hydraulic chamber 19, brake pedal 20, normally closed solenoid valve 21, normally open solenoid valve 22, hydraulic pressure sensor 23, pedal stroke sensor 24, simulator piston 25, hydraulic chamber 26, spring chamber 27, simulator return spring 28 , Simulator rubber spring 29, one-way valve 30, reversing valve 31, rotary motor 32, pinion 33, large gear 34, crank 35, connecting rod 36, slider 37, linear pressure regulating valve.

Detailed ways

See Figure 1-5:

The utility model provides a brake-by-wire system capable of simulating pedal feeling. The specific structure includes a brake master cylinder 1, a master cylinder driving device 2, a brake wheel cylinder 3, a liquid storage tank 4, a secondary master cylinder 5, a pedal Push rod 6, pedal feel simulator 7 and electronic control unit ECU 8, wherein the brake master cylinder 1 includes a master cylinder push rod 9, a master cylinder piston 10 and a master cylinder return spring 11, the master cylinder piston 10 and the cylinder A master cylinder hydraulic chamber 12 is formed between the bodies, and the master cylinder return spring 11 is arranged in the master cylinder hydraulic chamber 12 to provide rebound force for the master cylinder piston 10; the master cylinder driving device 2 is connected with the master cylinder push rod 9, and the master cylinder pushes the The rod 9 is connected to the master cylinder piston 10 through the front end of the cylinder body, and pushes the master cylinder piston 10 to build pressure in the master cylinder hydraulic chamber 12; The wheel cylinders 3 are connected, and each brake wheel cylinder 3 is connected to the liquid storage tank 4 through pipelines provided with pressure reducing valves 14 respectively; the secondary master cylinder 5 is sequentially equipped with a first piston 15 and a second piston 16, A first hydraulic chamber 17 and a second hydraulic chamber 18 are sequentially formed between a piston 15, a second piston 16 and the bottom of the cylinder. The first hydraulic chamber 17 and the second hydraulic chamber 18 are provided with a return spring, and the brake pedal 19 Connected to the pedal push rod 6, the pedal push rod 6 is connected to the first piston 15 through the front end of the secondary master cylinder 5, and the first hydraulic chamber 17 of the secondary master cylinder 5 is connected to the hydraulic chamber 25 of the pedal feel simulator 7 through a pipeline The second hydraulic chamber 18 of the secondary master cylinder 5 is respectively connected with the liquid storage tank 4 through the pipeline provided with the normally closed solenoid valve 20, and is connected with the brake wheel cylinder 3 through the pipeline provided with the normally open solenoid valve 21. The liquid inlet of the booster valve 13 is connected; the electronic control unit ECU8 is respectively connected with the booster valve 13 , the pressure reducing valve 14 , the normally closed solenoid valve 20 , and the normally open solenoid valve 21 .

The boosting valve 13 is a normally open solenoid valve, and the pressure reducing valve 14 is a normally closed solenoid valve.

The utility model also includes a hydraulic pressure sensor 22 and a pedal stroke sensor 23. The hydraulic pressure sensor 22 is connected with the liquid outlet of the hydraulic chamber 12 of the master cylinder and the booster valve 13 of each wheel brake cylinder 3, and measures the master cylinder. The hydraulic pressure of the liquid outlet of the hydraulic chamber 12 and the hydraulic pressure of each brake wheel cylinder 3; the pedal stroke sensor 23 is provided on the pedal push rod 6 to detect the displacement data of the pedal push rod 6; the hydraulic pressure sensor 22 and the pedal The stroke sensors 23 are respectively connected with the electronic control unit ECU8, and transmit data to the electronic control unit ECU8 in real time.

The pedal feel simulator 7 is divided into a hydraulic chamber 25 and a spring chamber 26 by a simulator piston 24. The spring chamber 26 is provided with a simulator return spring 27 and a simulator rubber spring 28, and the simulator return spring 27 is connected to the simulator. Between the piston 24 and the bottom of the simulator cylinder, the simulator rubber spring 28 is located inside the simulator return spring 27 , and one end is fixed on the simulator piston 24 .

A one-way valve 29 is provided on the pipeline between the first hydraulic chamber 17 of the secondary master cylinder 5 and the pedal feel simulator 7 , that is, the hydraulic chamber 25 of the pedal feel simulator 7 leads to the first hydraulic chamber of the secondary master cylinder 5 17. When the first piston 15 of the secondary master cylinder 5 is reset, the brake fluid in the hydraulic chamber 25 of the pedal feel simulator 7 flows back to the first hydraulic chamber 17 of the secondary master cylinder 5 through the one-way valve 29; and The one-way valve 29 is provided with a reversing valve 30 in parallel. The reversing valve 30 is a two-position five-way solenoid valve. The liquid inlet is connected to the first hydraulic chamber 17 of the secondary master cylinder 5 through a pipeline. The direction valve 30 is in the left position, so the left position liquid outlet is normally open, and is connected to the hydraulic chamber 25 of the pedal feel simulator 7. When the power is turned on, the reversing valve 30 is in the right position, so the right position liquid outlet is in a normally closed state, The liquid storage tank 4 is connected; the reversing valve 30 is connected to the electronic control unit ECU8 through a line, and the reversing is controlled by the electronic control unit ECU8.

The liquid storage tank 4 is connected to the hydraulic inlet of the master cylinder hydraulic chamber 12 of the master brake cylinder 1, the first hydraulic chamber 17 and the second hydraulic chamber 18 of the secondary master cylinder 5 respectively through pipelines, and is connected to the hydraulic chamber 12 of the master cylinder. , The first hydraulic chamber 17 and the second hydraulic chamber 18 are supplemented with brake fluid.

The master cylinder driving device 2 includes a rotary motor 31, a pinion gear 32, a large gear 33, a crank 34, a connecting rod 35, and a slider 36, wherein the output shaft of the rotary motor 31 and the pinion gear 32 are coaxially arranged, and the large gear 33 and the small gear 32 are arranged coaxially. The gear 32 is meshed to form a first-level deceleration and torque increasing mechanism. One end of the crank 34 is fixed in the center of the large gear 33, and is arranged radially along the large gear 33. The block 36 is connected with the master cylinder push rod 9 of the brake master cylinder 1, and the slider 36 is arranged in the slideway and moves in translation in the slideway; the rotating electrical machine 31 is connected with the electronic control unit ECU8, which is sent and controlled by the electronic control unit ECU8 The signal controls its rotation.

A linear pressure regulating valve 37 is also provided on the pipeline between the pressure reducing valve 14 of the brake wheel cylinder 3 and the liquid storage tank 4, and the linear pressure regulating valve 37 is a normally open solenoid valve with adjustable duty ratio, It is connected to the electronic control unit ECU8 through a line, and the opening degree is controlled and adjusted by the electronic control unit ECU8.

The connection modes of the above-mentioned electronic control unit ECU8 to each solenoid valve and sensor are all line connections.

The working principle of the present utility model:

1. Conventional braking:

When the driver depresses the brake pedal 19, the electronic control unit ECU8 controls the normally closed solenoid valve 20 to be energized to open, the normally open solenoid valve 21 is energized to close, the reversing valve 30 is in the left position, connected to the pedal feel simulator 7, and the pedal push rod 6. Push the first piston 15 of the secondary master cylinder 5 to start moving, and then push the second piston 16 to move through the return spring. Since the normally closed solenoid valve 20 is opened, the normally open solenoid valve 21 is closed, and the second The brake fluid flowing out of the hydraulic chamber 18 always closes the solenoid valve 20 and flows back to the reservoir 4, and the brake fluid from the first hydraulic chamber 17 of the secondary master cylinder 5 flows into the pedal feel simulator 7 through the reversing valve 30. The two hydraulic chambers of the master cylinder 5 do not build up pressure.

On the other hand, the pedal stroke sensor 23 obtains the pedal displacement information and transmits it to the electronic control unit ECU8. After the electronic control unit ECU8 receives the signal, it calculates the total braking force demand, and then obtains the required braking force according to the working characteristics of the master cylinder drive device 2. The electric control unit ECU8 sends a control signal to the rotary motor 31 to drive it to rotate, and the rotary motor 31 pushes the master cylinder piston through the first-stage deceleration and torque increasing mechanism, the crank connecting rod structure, the slider 36 and the master cylinder push rod 9 10 moves, the master cylinder piston 10 builds pressure in the master cylinder hydraulic chamber 12, and the brake fluid in the master cylinder hydraulic chamber 12 transmits the braking force to each brake wheel cylinder 3 through the hydraulic pipeline.

Conventional braking can be divided into three processes: boosting, maintaining pressure and decompressing.

a) Pressurization process

When the driver depresses the brake pedal 19, the normally closed solenoid valve 20 is opened, the normally open solenoid valve 21 is closed, and the reversing valve 30 is in the left position; the four booster valves 13 connected to each wheel cylinder 3 are cut off When it is electrically turned on, the four pressure reducing valves 14 are all turned off and closed, and the brake fluid enters the brake wheel cylinder 3 from the master cylinder hydraulic chamber 12 of the brake master cylinder 1 to build up pressure.

b) Pressure holding process

When the electronic control unit ECU8 decides that the braking system needs to maintain pressure, the four boosting valves 13 are all energized and closed, and the four pressure reducing valves 14 are all powered off and closed. At this time, the brake fluid in the brake wheel cylinder 3 and the brake The braking pressure in the brake wheel cylinder 3 remains unchanged.

c) Decompression process

When the driver releases the brake pedal 19 or the control strategy decides that the brake wheel cylinder 3 needs to reduce the pressure, the electronic control unit ECU8 controls the four pressure boosting valves 13 to be energized and closed, and the four pressure reducing valves 14 to be energized to open. At this time, the brake fluid in the wheel brake cylinder 3 flows back to the liquid storage tank 4 through the pipeline of the pressure reducing valve 14, and the pressure of the wheel brake cylinder 3 is reduced to complete the pressure reduction process.

Pedal Feel Simulator 7 simulates the process of pedal force:

During the normal braking process, the pedal is completely decoupled, that is, the driver is only responsible for giving the target braking pressure, while the actual boosting process is controlled by the electronic control unit ECU8 to control the master cylinder drive device 2, the master brake cylinder 1 and each solenoid valve. Completed, the pedal feel simulator 7 provides the driver with the same pedal feel as the conventional brake system according to the pedal force and pedal displacement curve of the conventional brake system.

During this process, the normally closed solenoid valve 20 is opened, the normally open solenoid valve 21 is closed, the reversing valve 30 is in the left position, and when the driver depresses the brake pedal 19, the brake fluid in the first hydraulic chamber 17 of the secondary master cylinder 5 It flows to the hydraulic chamber of the pedal feeling simulator 7 through the reversing valve 30 and acts on the simulator piston 24 to push the simulator piston 24 to move towards the bottom of the simulator cylinder. When the pedal displacement is small, the pedal reaction force is generated by the simulator return spring 27; as the pedal displacement increases, the simulator piston 24 continues to move until the simulator rubber spring 28 contacts the bottom of the simulator cylinder, after which the simulator The rubber spring 28 and the simulator return spring 27 are connected in parallel to provide the pedal reaction force. Since the simulator rubber spring 28 has nonlinear elastic force, it can satisfy the nonlinear relationship between the pedal displacement and the pedal force when the pedal displacement is large, and simulate driving better. operator's pedal feel.

In order to meet the feeling requirements of the brake pedal 19 of different types of drivers, the adjustment of the reversing valve 30 by the electronic control unit ECU8 can be realized. When the reversing valve 30 is switched to the right position, the first hydraulic chamber 17 of the secondary master cylinder 5 is communicated with the liquid storage tank 4, and the brake fluid in the first hydraulic chamber 17 flows into the liquid storage tank 4 through the reversing valve 30, At this time, the pedal feel simulator 7 does not provide simulated pedal force, and the pedal force is provided by the return spring in the secondary master cylinder 5, so that under the same pedal displacement, the generated pedal reaction force becomes smaller. The electronic control unit ECU8 controls the switching of the reversing valve 30 between the left position and the right position, thus realizing the adjustment of the pedal reaction force, which can match drivers with different driving styles.

The control process of brake wheel cylinder pressure:

In the braking system of the present invention, the four pressure-increasing valves 13 and the four pressure-reducing valves 14 are all on-off valves, with only two states: open and closed. A linear pressure regulating valve 37 is connected to the common pipeline of the pressure reducing valve 14 flowing into the liquid storage tank 4 . The electronic control unit ECU8 receives the signals of the pedal stroke sensor 23 and the hydraulic pressure sensor 22, and after analysis and decision-making, controls the opening of the linear pressure regulating valve 37 according to the actual needs of the system, that is, controls the flow of the brake wheel cylinder 3 back to the liquid storage tank 4. The flow rate of the dynamic fluid, and then the accurate control of the pressure is realized.

2. Active braking:

Since the brake system pedal of the present invention is completely decoupled, the braking operation can be performed independently of the pedal force of the driver. Taking the emergency braking of a car as an example, when an emergency situation occurs in front of the car, the electronic control unit ECU8 of the braking system sends a control signal to the rotating electric machine 31 through decision-making and judgment, and the master cylinder driving device 2 makes the brake master cylinder. 1 Quick build pressure. At this time, the four pressure-increasing valves 13 in the braking system are all turned on, and the four pressure-reducing valves 14 are all turned off, and the brake fluid enters the brake wheel cylinder 3 from the brake master cylinder 1 to build pressure.

3. Failed backup:

When the braking system is powered off or the electronic control unit ECU8 fails, the normally closed solenoid valve 20 is powered off, the normally open solenoid valve 21 is powered off, the reversing valve 30 is in the left position, and the four booster valves 13 are powered off. Open, the four pressure reducing valves 14 are all powered off and closed. When the driver depresses the brake pedal 19, the brake fluid in the first hydraulic chamber 17 of the secondary master cylinder 5 flows into the pedal feel simulator 7 through the reversing valve 30, and the brake fluid in the second hydraulic chamber 18 of the secondary master cylinder 5 flows into the pedal feel simulator 7. It flows to the brake wheel cylinder 3, so that the wheel can obtain enough braking force to realize the backup function of failure.

Claims (8)

1. A brake-by-wire system capable of simulating pedal feeling, characterized in that: comprising a brake master cylinder, a master cylinder drive device, a brake wheel cylinder, a liquid storage tank, a secondary master cylinder, a pedal push rod, and a pedal feel simulation The brake master cylinder includes a master cylinder push rod, a master cylinder piston and a master cylinder return spring, a master cylinder hydraulic chamber is formed between the master cylinder piston and the cylinder body, and the master cylinder return spring is located in the Inside the master cylinder hydraulic chamber; the master cylinder driving device is connected with the master cylinder push rod, which can push the master cylinder piston to build pressure in the master cylinder hydraulic chamber; the master cylinder hydraulic chamber is connected with the brake wheel cylinder through the pipeline, and the brake wheel cylinder passes through the The pipeline is connected with the liquid storage tank; a first piston and a second piston are sequentially assembled in the secondary master cylinder, and a first hydraulic chamber and a second hydraulic chamber are sequentially formed between the first piston, the second piston and the bottom of the cylinder body, and the A hydraulic chamber and a second hydraulic chamber are provided with return springs, the pedal push rod is connected to the first piston through the front end of the secondary master cylinder, and the first hydraulic chamber of the secondary master cylinder is connected to the pedal feel simulator through a pipeline. The second hydraulic chamber of the secondary master cylinder is respectively connected with the liquid storage tank through the pipeline with the normally closed solenoid valve, and is connected with the brake wheel cylinder through the pipeline with the normally open solenoid valve; the electronic control unit ECU is respectively connected with the normally closed solenoid valve. The closed solenoid valve and the normally open solenoid valve are connected. 2. A kind of brake-by-wire system capable of simulating pedal feeling according to claim 1, characterized in that: a booster valve is provided on the pipeline between the hydraulic chamber of the master cylinder and the wheel brake cylinder, and the wheel brake cylinder is connected to the brake wheel cylinder. There is a pressure reducing valve on the pipeline between the liquid storage tanks; the boosting valve is a normally open solenoid valve, and the pressure reducing valve is a normally closed solenoid valve; the boosting valve and the pressure reducing valve are respectively connected with the electronic control unit ECU connected. 3. A brake-by-wire system capable of simulating pedal feeling according to claim 2, characterized in that it further comprises a hydraulic pressure sensor and a pedal stroke sensor, and the hydraulic pressure sensor is connected to the master cylinder hydraulic chamber and the brake wheel. Each booster valve of the cylinder is connected to measure the hydraulic pressure of the liquid outlet of the hydraulic chamber of the master cylinder and the hydraulic pressure of each brake wheel cylinder; the pedal stroke sensor is arranged on the pedal push rod to detect the displacement data of the pedal push rod ; The hydraulic pressure sensor and the pedal stroke sensor are respectively connected with the electronic control unit ECU, and transmit the data to the electronic control unit ECU in real time. 4. A brake-by-wire system capable of simulating pedal feeling according to claim 1, characterized in that: the pedal feeling simulator is divided into a hydraulic chamber and a spring chamber by a simulator piston, and the first hydraulic pressure of the secondary master cylinder is divided into a hydraulic chamber and a spring chamber. The cavity is connected with the hydraulic cavity of the pedal feeling simulator through a pipeline; the spring cavity is provided with a simulator return spring and a simulator rubber spring, and the simulator return spring is connected between the simulator piston and the bottom of the simulator cylinder. During this time, the simulator rubber spring is located inside the simulator return spring, and one end is fixed on the simulator piston. 5. A brake-by-wire system capable of simulating pedal feel according to claim 4, wherein a check valve is provided on the pipeline between the first hydraulic chamber of the secondary master cylinder and the pedal feel simulator, When the first piston of the secondary master cylinder is reset, the brake fluid in the hydraulic chamber of the pedal feel simulator flows back to the first hydraulic chamber of the secondary master cylinder through the one-way valve; a reversing valve is arranged in parallel with the one-way valve , the reversing valve is a two-position five-way solenoid valve, the liquid inlet is connected to the first hydraulic chamber of the secondary master cylinder through a pipeline, and the left liquid outlet is normally open, which is connected to the hydraulic chamber of the pedal feeling simulator , the right liquid outlet is normally closed, connected to the liquid storage tank; the reversing valve is connected to the electronic control unit ECU through the line, and the electronic control unit ECU controls the reversing. 6. A brake-by-wire system capable of simulating pedal feel according to claim 1, wherein the liquid storage tank is connected to the master cylinder hydraulic chamber and the secondary master cylinder of the brake master cylinder respectively through pipelines. The first hydraulic chamber is connected with the liquid inlet of the second hydraulic chamber, and the brake fluid is supplemented to the master cylinder hydraulic chamber, the first hydraulic chamber and the second hydraulic chamber. 7. A brake-by-wire system capable of simulating pedal feel according to claim 1, wherein the master cylinder driving device comprises a rotary motor, a pinion, a large gear, a crank, a connecting rod, and a slider, Among them, the output shaft of the rotary motor is arranged coaxially with the pinion, the large gear is meshed with the pinion, one end of the crank is fixed in the center of the large gear, and is arranged radially along the large gear, the other end is hinged with the connecting rod, and the other end of the connecting rod is connected with the slider Hinged, the slider is connected with the push rod of the master cylinder of the brake master cylinder, the slider is arranged in the slideway, and translates in the slideway; the rotating motor is connected with the electronic control unit ECU, which is controlled by the control signal sent by the electronic control unit ECU its rotation. 8. The brake-by-wire system capable of simulating pedal feeling according to claim 2, wherein a linear pressure regulating valve is also provided on the pipeline between the pressure reducing valve of the brake wheel cylinder and the liquid storage tank, The linear pressure regulating valve is a normally open solenoid valve with adjustable duty ratio, and is connected to the electronic control unit ECU through a circuit, and the opening degree is controlled and adjusted by the electronic control unit ECU.

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