CN103010199A - Brake-by-wire system of automobile - Google Patents

Abstract

The invention relates to an automobile brake system by wire, which belongs to the technical field of automobile brake systems. The brake system replaces the vacuum booster of the traditional vacuum booster hydraulic brake system with an electric motor, which pushes the piston in the brake master cylinder to generate brake hydraulic pressure, thereby canceling the dependence on the vacuum degree of the engine; using the pedal simulator, Eliminate the impact on the feeling of the brake pedal during coordinated control with feedback braking; retain the hydraulic control unit of the existing braking system to implement hydraulic adjustment; integrate a backup hydraulic braking system, which can be implemented by the driver when the system power supply fails. Strong braking. Compared with the existing distributed brake-by-wire solution, the brake system of the present invention has less structural changes than the traditional vacuum-assisted hydraulic brake system, more convenient layout on the vehicle, and can inherit more traditions in terms of control. Existing technology in braking systems.

Description

An automobile brake-by-wire system

technical field

The invention relates to an automobile braking system by wire, which belongs to the technical field of automobile braking systems.

Background technique

The development of hybrid electric vehicles and electric vehicles has put forward new requirements for the braking system of automobiles. The braking system used for hybrid electric vehicles and electric vehicles (called friction braking system to distinguish it from regenerative braking), in order to achieve good cooperation with the regenerative braking system of hybrid electric vehicles and electric vehicles, the brake On the basis of safety, the regenerative braking system can recover as much braking energy as possible. Firstly, the dependence on engine vacuum should be eliminated, and secondly, the coordinated control with the regenerative braking system should not affect the feeling of the brake pedal. In the existing vacuum-assisted hydraulic braking system, the vacuum booster depends on the vacuum degree of the engine, and when coordinated with regenerative braking, its hydraulic control will affect the capacity and hydraulic pressure of the master cylinder, thereby affecting the feeling of the brake pedal. In order to overcome the above-mentioned deficiencies of existing braking systems, engineers began to develop several new braking systems in the 1990s, some of which were used in hybrid vehicles and electric vehicles in this century. The new brake system currently announced has the following schemes: The first type is represented by Toyota's ECB system (SAE paper 2002-01-0300): the pump is driven by a motor, and the brake fluid is pumped into the accumulator. The high pressure is established in the medium to directly supply the braking needs, so that the braking system cancels the dependence on the vacuum degree of the engine; the brake-by-wire technology is adopted to disconnect the mechanical/hydraulic connection between the brake pedal and the brake (that is, pedal decoupling), and adopts The pedal simulator provides the driver with a brake pedal feel so that the coordinated control of friction braking and regenerative braking does not affect the brake pedal feel. A disadvantage of this type of system is that the high pressure maintained in the accumulator is a safety hazard, and in the event of a collision, the accumulator becomes a "cannonball" that poses a threat to the occupants. The second type of system is similar to the first type of system, represented by the scheme announced by Honda in SAE paper 2007-01-0868, which also establishes hydraulic pressure in the accumulator through the motor and pump, the difference is that the accumulator is not directly The brake fluid is supplied to the brakes, but the hydraulic pressure is applied to the master cylinder piston, and the master cylinder piston pushes the brake fluid in the master cylinder to generate brake hydraulic pressure. This type of system suffers from the same problems as the first type of system. Another type of solution is represented by Continental's RBS system (SAE paper 2009-01-1217), which uses a vacuum pump to provide vacuum to the electronic vacuum booster, thereby canceling the dependence on engine vacuum, and using a pedal simulator to eliminate Effect on brake pedal feel when combined with regenerative braking. In this solution, the electromagnet of the electronic vacuum booster has problems such as thermal decay. Another type of solution is represented by Nissan's e-ACT system (SAE paper 2011-01-0572), which uses a motor for power boosting, thereby canceling the dependence on the vacuum degree of the engine; the first chamber piston of the master cylinder is hollow, and its hole There is a plunger in the middle, and a pair of pressure compensation springs are installed between the plunger and the piston in the first chamber; the piston in the first chamber is driven by a motor, and the plunger is pushed by a brake pedal; the motor controls the piston in the first chamber to adjust the pressure. In order to eliminate the impact on the plunger stroke and the brake pedal stroke, a pair of pressure compensation springs are used to eliminate the impact on the pedal force during pressure adjustment, so as to ensure that the brake pedal feel is not affected. The disadvantage of this solution is that the piston in the first chamber of the master cylinder controlled by the motor cannot move backwards at the initial position to decompress. When the braking strength is relatively small and the regenerative braking can independently meet the braking strength requirements, driving The operator depresses the brake pedal and pushes the plunger in the first cavity piston of the master cylinder to move forward to establish a certain brake hydraulic pressure, which should be reduced, but because the piston of the first cavity of the master cylinder controlled by the motor cannot The position moves backward to implement decompression, so it will have an adverse effect on the total braking force and regenerative braking force. Another type of solution adopts a distributed brake-by-wire system, uses the motor as the source of braking force, cancels the dependence on the vacuum degree of the engine, and uses a pedal simulator to eliminate the adverse effect on the pedal feel when it cooperates with regenerative braking. The solutions that do not use brake fluid are represented by Continental's EMB and Siemens' EWB. The brake actuator needs to be placed on the side of the wheel, and the working environment is relatively harsh. The scheme of using brake fluid is represented by Delphi Corporation and DEHB of Tsinghua University. The brake actuator can be placed above the suspension, and the working environment is greatly improved. However, the distributed structure is not as good as that of the traditional brake system. There are some inconveniences in installation and layout due to major changes.

Contents of the invention

The purpose of the present invention is to propose a brake-by-wire system for automobiles, which replaces the vacuum booster of the traditional vacuum booster hydraulic brake system with a motor, and pushes the piston in the brake master cylinder to move to generate brake hydraulic pressure, thus canceling the need for engine vacuum. degree of dependence; use a pedal simulator to eliminate the impact on the brake pedal feel when coordinating control with regenerative braking; retain the hydraulic control unit of the existing braking system to implement hydraulic adjustment; integrate a backup hydraulic braking system and supply power to the system In case of failure, the driver can apply a certain intensity of braking.

The automobile brake-by-wire system proposed by the present invention includes a master cylinder shell, a piston in the first inner chamber of the master cylinder, a spring in the first inner chamber of the master cylinder, a piston in the second inner chamber of the master cylinder, a spring in the second inner chamber of the master cylinder, a motor, and a nut. , screw rod, first bearing, second bearing, push rod housing, push rod, brake pedal, simulator valve, isolation valve, simulator, hydraulic control unit, left front brake, right front brake, left rear brake, right rear Brakes, brake pedal sensors and controls;

The piston in the first cavity of the master cylinder and the piston in the second cavity of the master cylinder are center valve pistons, the piston in the first cavity of the master cylinder and the piston in the second cavity of the master cylinder are placed in the shell of the master cylinder, and the first cavity of the master cylinder Cavity piston, master cylinder second inner cavity piston and master cylinder shell enclose the master cylinder first inner cavity, the master cylinder first inner cavity spring is placed in the master cylinder first inner cavity, the master cylinder second inner cavity piston and the master cylinder shell form the second inner cavity of the master cylinder, the spring in the second inner cavity of the master cylinder is placed in the second inner cavity of the master cylinder; the left end of the screw rod is placed in the master cylinder shell, the screw rod, the second inner cavity of the master cylinder A cavity The piston and the master cylinder shell form a screw rod cavity, and the first cavity of the master cylinder and the second cavity of the master cylinder are respectively connected to the hydraulic control unit through the brake pipeline;

The motor includes a motor housing, a motor stator, a motor rotor and a nut; the motor housing is fixedly connected to the main cylinder housing, the motor stator is fixed on the motor housing, and the motor rotor is supported by the first bearing and the second bearing In the motor casing, the motor rotor is a hollow structure, the nut is placed in the hollow hole of the motor rotor, and is fixedly connected with the motor rotor; the screw rod and the nut are coaxially assembled to form a kinematic pair, and the The rotary motion of the motor rotor is converted into the translational motion of the screw;

The push rod housing is fixedly connected with the motor housing, the push rod is placed in the push rod housing, the push rod and the push rod housing enclose the inner chamber of the push rod, and the push rod is hinged to the brake pedal. Connected, the inner chamber of the push rod is connected to the simulator valve through the brake pipeline, and is connected to the isolation valve through the brake pipeline. The simulator valve is a normally closed two-position two-way solenoid valve. The pipeline is connected to the simulator, and the isolation valve is a normally open two-position two-way solenoid valve, which is connected to the inner cavity of the screw rod through the brake pipeline;

Described simulator comprises simulator piston, simulator spring and simulator shell, and simulator piston and simulator spring are placed in simulator shell;

The hydraulic control unit is an anti-lock brake hydraulic control unit or a vehicle stability control hydraulic control unit;

The left front brake, right front brake, left rear brake and right rear brake are respectively connected to the hydraulic control unit through brake pipelines;

The brake pedal sensor is installed on the pushrod housing, used to collect the brake pedal signal, and transmit the signal to the controller, and the brake pedal sensor is connected to the controller through the signal line;

The controller is used to collect the brake pedal signal transmitted by the brake pedal sensor and the signals of the wheel speed sensor, the steering wheel angle sensor, the yaw rate sensor and the lateral acceleration sensor, and control the motor, the simulator valve, the isolation valve and the The hydraulic control unit realizes the braking function.

The automobile brake-by-wire system proposed by the present invention has the advantages of: compared with the scheme using accumulators in the prior art, it has the advantage of not needing to accumulate high pressure at ordinary times, thereby reducing potential safety hazards; Compared with the solution of electronic vacuum booster, the vacuum pump has the advantages of high pressure control precision and little influence of thermal recession; The invention is a brake-by-wire system. When the total braking force demand is small and the feedback braking can independently meet the braking demand, the brake pedal is stepped on, and the friction braking system does not establish brake hydraulic pressure, eliminating the need for the total The adverse effects of braking force and feedback braking force; compared with the distributed brake-by-wire scheme of the prior art, the structural improvement of the traditional vacuum-assisted hydraulic braking system is small, the arrangement on the vehicle is more convenient, and the control can Inherit more existing technologies of traditional braking systems.

Description of drawings

Fig. 1 is a schematic structural diagram of an automobile brake-by-wire system proposed by the present invention.

In Fig. 1, 1 is the main cylinder shell, 2 is the second inner cavity of the main cylinder, 3 is the spring in the second inner cavity of the main cylinder, 4 is the piston in the second inner cavity of the main cylinder, 5 is the first inner cavity of the main cylinder, and 6 is The first cavity spring of the master cylinder, 7 the piston of the first cavity of the master cylinder, 8 the inner cavity of the screw rod, 9 the screw rod, 10 the nut, 11 the first bearing, 12 the motor casing, and 13 the motor stator , 14 is the motor rotor, 15 is the second bearing, 16 is the inner cavity of the push rod, 17 is the push rod, 18 is the push rod housing, 19 is the brake pedal, 21 is the simulator valve, 23 is the simulator piston, 24 is the simulator spring, 25 is the simulator, 27 is the isolation valve, 31 is the hydraulic control unit, 36 is the left front brake, 37 is the right front brake, 38 is the left rear brake, 39 is the right rear brake, 20, 22, 26, 28 , 29, 30, 32, 33, 34, 35 are brake pipelines, 40 is a brake pedal sensor, and 41 is a controller.

Detailed ways

The car brake-by-wire system proposed by the present invention has a structure as shown in Figure 1, including a master cylinder housing 1, a master cylinder first cavity piston 7, a master cylinder first cavity spring 6, and a master cylinder second cavity piston 4 , master cylinder second inner cavity spring 3, motor, nut 10, screw rod 9, first bearing 11, second bearing 15, push rod housing 18, push rod 17, brake pedal 19, simulator valve 21, isolation Valve 27, simulator, hydraulic control unit 31, left front brake 36, right front brake 37, left rear brake 38, right rear brake 39.

The first inner chamber piston 7 of the master cylinder and the second inner chamber piston 4 of the master cylinder use the central valve piston used in the prior art; the first inner chamber piston 7 of the master cylinder and the second inner chamber piston 4 of the master cylinder are placed in the main cylinder In the cylinder shell 1; the first cavity piston 7 of the master cylinder, the piston 4 of the second cavity of the master cylinder and the master cylinder shell 1 enclose the first cavity 5 of the master cylinder, and the spring 6 of the first cavity of the master cylinder is placed in the second cavity of the master cylinder In the first inner cavity 5; the second inner cavity piston 4 of the master cylinder and the master cylinder shell 1 enclose the second inner cavity 2 of the master cylinder, and the spring 3 of the second inner cavity of the master cylinder is placed in the second inner cavity 2 of the master cylinder; the screw rod The left end of 9 is placed in the main cylinder shell 1, and the screw rod 9, the first inner cavity piston 7 of the master cylinder and the main cylinder shell 1 enclose the inner cavity 8 of the screw rod; the first inner cavity 5 of the master cylinder is connected to the The hydraulic control unit 31 is connected, and the second inner cavity 2 of the master cylinder is connected with the hydraulic control unit 31 through the brake pipeline 29; the following three technologies use the existing technology of the traditional vacuum-assisted hydraulic braking system: the first inner cavity 5 of the master cylinder The injection of the brake fluid in the second inner cavity 2 of the master cylinder is realized through the oil pot, and the sealing of the brake fluid in the first inner cavity 5 of the master cylinder and the second inner cavity 2 of the master cylinder is achieved by the piston 7 and the first inner cavity of the master cylinder. The sealing ring on the piston 4 in the second inner chamber of the master cylinder is realized, and the position limitation of the piston 7 in the first inner chamber of the master cylinder and the piston 4 in the second inner chamber of the master cylinder can be realized by the control pin, wherein the oil pot, the sealing ring, the control pin Not shown in the etc. figure.

The motor includes a motor housing 12, a motor stator 13, and a motor rotor 14; the motor housing 12 is fixedly connected to the main cylinder housing 1 by fasteners such as screws; the motor stator 13 is fixed on the motor housing 12; The motor rotor 14 is supported in the motor housing 12 through the first bearing 11 and the second bearing 15; the motor rotor 14 is hollow, and the nut 10 is placed in the hollow hole of the motor rotor 14, and is connected with The motor rotor 14 is fixedly connected; the screw mandrel 9 and the nut 10 are coaxially assembled to form a kinematic pair, which converts the rotational motion of the motor rotor 14 into the translational motion of the screw mandrel 9 .

The push rod housing 18 is fixedly connected with the motor housing 12 by fasteners such as screws; the push rod 17 is placed in the push rod housing 18; the push rod 17 and the push rod housing 18 form a Push rod inner cavity 16; said push rod 17 is hinged with said brake pedal 19; said push rod inner cavity 16 is connected with simulator valve 21 through brake pipeline 20, and is isolated from brake pipeline 26 The valve 27 is connected; the simulator valve 21 is a normally closed two-position two-way solenoid valve, which is connected to the simulator through the brake pipeline 22; the isolation valve 27 is a normally open two-position two-way solenoid valve, The moving pipeline 28 is connected with the inner cavity 8 of the screw mandrel.

The simulator includes a simulator piston 23, a simulator spring 24, and a simulator housing 25; the simulator piston 23 and the simulator spring 24 are placed in the simulator housing 25.

The hydraulic control unit 31 is an anti-lock brake hydraulic control unit used in the prior art, or a vehicle stability control hydraulic control unit used in the prior art, preferably a vehicle stability control hydraulic control unit.

The left front brake 36 , right front brake 37 , left rear brake 38 , and right rear brake 39 are connected to the hydraulic control unit 31 through brake pipelines 32 , 33 , 34 , 35 respectively.

The brake pedal sensor 40 collects the brake pedal signal and transmits it to the controller 41;

The controller 41 collects the brake pedal signal transmitted by the brake pedal sensor 40 and the signals transmitted by the sensors such as the wheel speed sensor, the steering wheel angle sensor, the yaw rate sensor, and the lateral acceleration sensor, and controls the motor, the simulator valve, etc. 21. Isolate the valve 27 and the hydraulic control unit 31, so as to realize various braking functions. The wheel speed sensor, steering wheel angle sensor, yaw rate sensor, and lateral acceleration sensor are technologies commonly used in passenger cars at present, so they are not described in detail in the present invention, nor shown in the drawings.

Below in conjunction with accompanying drawing, introduce in detail the working principle and working process of the automobile brake-by-wire system that the present invention proposes:

When the system is working normally, the function of the motor is to replace the driver and the vacuum booster in the traditional vacuum booster hydraulic braking system, and push the piston 7 in the first inner chamber of the master cylinder and the piston 4 in the second inner chamber of the master cylinder to generate brake hydraulic pressure. . Specifically, when the controller 41 detects that the brake pedal 19 is depressed through the pedal signal transmitted by the brake pedal sensor 40, the control simulator valve 21 is energized and opened, so that the push rod inner cavity 16 passes through the brake pipeline 20, The simulator valve 21 and the brake pipeline 22 are connected to the simulator; the isolation valve 27 is controlled to be energized and closed, so that the inner cavity of the push rod 16 is disconnected from the inner cavity of the screw rod 8 . Like this, continue to step on the brake pedal 19, and the push rod 17 will press the brake fluid in the push rod inner chamber 16 into the simulator through the brake pipeline 20, the simulator valve 21, and the brake pipeline 22, thereby providing the driver The brake pedal stroke is provided; the brake fluid pressed into the simulator pushes the simulator piston 23 to compress the simulator spring 24, and the elastic force of the simulator spring 24 provides the driver with pedal force. The controller 41 detects the pedal signal transmitted by the brake pedal sensor 40, determines the magnitude of the target output torque of the motor, and controls the actual output torque of the motor to follow the target output torque of the motor. The output torque of the motor is converted into the output thrust of the screw rod 9 through the nut 10 and the screw rod 9, and through the movement of the screw rod 9 in the screw rod inner cavity 8, the brake fluid in the screw rod inner cavity 8 is pushed, thereby pushing the main The piston 7 in the first cavity of the cylinder and the piston 4 in the second cavity of the master cylinder pass the brake fluid in the first cavity 5 of the master cylinder and the second cavity 2 of the master cylinder through the brake pipeline 30 and the brake pipeline respectively. 29. Push in the hydraulic control unit 31, and then push in each brake through the hydraulic control unit 31 and the brake pipeline connected with each brake, so as to brake the vehicle. When necessary, such as in the case of anti-lock braking, or in the case of coordinated control with regenerative braking, the hydraulic control unit 31 adjusts the brake hydraulic pressure, and then passes through the brake pipelines 32, 33, 34, 35 to the left front Brake 36, right front brake 37, left rear brake 38, right rear brake 39 transmit hydraulic pressure and implement braking.

In the braking system of the present invention, the active supercharging can be realized by the motor, which is used to realize control functions such as active collision avoidance and self-adaptive cruise. When the hydraulic control unit 31 uses the vehicle stability control hydraulic control unit in the prior art, the hydraulic control unit 31 can also realize active boosting, so as to implement vehicle stability control.

When the hydraulic control unit 31 uses the vehicle stability control hydraulic control unit in the prior art, if the motor of the system of the present invention fails and the hydraulic control unit 31 can work normally, then conventional braking and anti-lock The realization of functions such as dead braking and stability control are all implemented by the hydraulic control unit 31 according to the prior art.

When both the motor and the hydraulic control unit 31 of the braking system of the present invention fail, the simulator valve 21 is de-energized and closed, and the isolation valve 27 is de-energized and opened. The pipeline 26 , the isolation valve 27 , and the brake pipeline 28 are connected with the inner cavity 8 of the screw rod. In this way, when the brake pedal 19 is stepped on, the push rod 17 will push the brake fluid in the push rod inner cavity 16 into the screw rod inner cavity 8 through the brake pipeline 26, the isolation valve 27, and the brake pipeline 28, thereby Push the piston 7 in the first inner cavity of the master cylinder and the piston 4 in the second inner cavity of the master cylinder, and pass the brake fluid in the first inner cavity 5 of the master cylinder and the second inner cavity 2 of the master cylinder through the brake pipeline 30 and the brake fluid respectively. The pipeline 29 is pushed into the hydraulic control unit 31, and then through the brake pipelines 32, 33, 34, 35 respectively, pushed into the left front brake 36, the right front brake 37, the left rear brake 38, and the right rear brake 39, thereby implementing the backup hydraulic system. move.

Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention rather than limit them. Although the present invention has been described in detail with reference to specific embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent replacements of the technical solutions without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the scope of the claims of the present invention.

Claims (1)

1. An automobile brake-by-wire system, characterized in that: the brake system includes a master cylinder shell, a piston in the first inner chamber of the master cylinder, a spring in the first inner chamber of the master cylinder, a piston in the second inner chamber of the master cylinder, and a piston in the second inner chamber of the master cylinder. Second cavity spring, motor, nut, lead screw, first bearing, second bearing, push rod housing, push rod, brake pedal, simulator valve, isolation valve, simulator, hydraulic control unit, left front brake, right front Brakes, left rear brake, right rear brake, brake pedal sensor and controller; The piston in the first cavity of the master cylinder and the piston in the second cavity of the master cylinder are center valve pistons, the piston in the first cavity of the master cylinder and the piston in the second cavity of the master cylinder are placed in the shell of the master cylinder, and the first cavity of the master cylinder Cavity piston, master cylinder second inner cavity piston and master cylinder shell enclose the master cylinder first inner cavity, the master cylinder first inner cavity spring is placed in the master cylinder first inner cavity, the master cylinder second inner cavity piston and the master cylinder shell form the second inner cavity of the master cylinder, the spring in the second inner cavity of the master cylinder is placed in the second inner cavity of the master cylinder; the left end of the screw rod is placed in the master cylinder shell, the screw rod, the second inner cavity of the master cylinder A cavity The piston and the master cylinder shell form a screw rod cavity, and the first cavity of the master cylinder and the second cavity of the master cylinder are respectively connected to the hydraulic control unit through the brake pipeline; The motor includes a motor housing, a motor stator, a motor rotor and a nut; the motor housing is fixedly connected to the main cylinder housing, the motor stator is fixed on the motor housing, and the motor rotor is supported by the first bearing and the second bearing In the motor casing, the motor rotor is a hollow structure, the nut is placed in the hollow hole of the motor rotor, and is fixedly connected with the motor rotor; the screw rod and the nut are coaxially assembled to form a kinematic pair, and the The rotary motion of the motor rotor is converted into the translational motion of the screw; The push rod housing is fixedly connected with the motor housing, the push rod is placed in the push rod housing, the push rod and the push rod housing enclose the inner chamber of the push rod, and the push rod is hinged to the brake pedal. Connected, the inner chamber of the push rod is connected to the simulator valve through the brake pipeline, and is connected to the isolation valve through the brake pipeline. The simulator valve is a normally closed two-position two-way solenoid valve. The pipeline is connected to the simulator, and the isolation valve is a normally open two-position two-way solenoid valve, which is connected to the inner cavity of the screw rod through the brake pipeline; Described simulator comprises simulator piston, simulator spring and simulator shell, and simulator piston and simulator spring are placed in simulator shell; The hydraulic control unit is an anti-lock brake hydraulic control unit or a vehicle stability control hydraulic control unit; The left front brake, right front brake, left rear brake and right rear brake are respectively connected to the hydraulic control unit through brake pipelines; The brake pedal sensor is installed on the pushrod housing, used to collect the brake pedal signal, and transmit the signal to the controller, and the brake pedal sensor is connected to the controller through the signal line; The controller is used to collect the brake pedal signal transmitted by the brake pedal sensor and the signals of the wheel speed sensor, the steering wheel angle sensor, the yaw rate sensor and the lateral acceleration sensor, and control the motor, the simulator valve, the isolation valve and the hydraulic control unit , to achieve the braking function.