CN104709259B - A kind of braking system with hydraulic assisting force - Google Patents

Abstract

The invention belongs to the technical field of automobile power-assisted braking, and relates to a hydraulic power-assisted braking system; Pedals and push rods; the electronic control unit is connected to the motor; the motor is connected to the roller screw mechanism; the roller screw mechanism is rigidly connected to the piston of the booster cylinder in the booster cylinder; the booster cylinder is connected to the three-chamber brake master cylinder through the oil circuit The booster cylinder is connected to the oil cup through the oil circuit; the brake pedal is rigidly connected with the push rod; the push rod is inserted into the three-chamber brake master cylinder; the three-chamber brake master cylinder includes the first chamber of the three-chamber brake master cylinder 1, the second cavity and the third cavity; the invention converts the rotational motion of the motor into the translational motion of the piston, which can also play a human role when the motor fails; the compression spring is used to simulate the feeling of the pedal, which can give the driver Good pedal feeling is provided; the present invention can be freely arranged on the whole vehicle and has a flexible structure.

Description

A hydraulic power-assisted braking system

technical field

The invention belongs to the technical field of automobile power-assisted braking, and relates to a hydraulic power-assisted braking system, in particular to a hydraulic power-assisted braking system suitable for electric vehicles.

Background technique

With the increasingly serious world environmental problems and energy crisis, countries around the world are encouraging research and development units to develop various types of new energy vehicles to deal with more and more complex environmental and energy issues. New energy vehicles mainly include gas vehicles, fuel cell electric vehicles, pure electric vehicles, liquefied petroleum gas vehicles, hydrogen energy vehicles, hybrid vehicles, solar vehicles and other new energy vehicles. Its waste gas emission is relatively low, it uses renewable energy, is clean and environmentally friendly, and integrates advanced vehicle technology, advanced design technology, and novel structure automobiles, which have broad market application prospects.

It is inevitable that new energy vehicles will gradually replace traditional vehicles. Among them, the development of electric vehicles is the fastest. Compared with other new energy sources such as hydrogen energy and solar energy, it has many advantages such as high energy density and low environmental impact. With the development of hydropower, nuclear power and other technologies, the development of electric energy in the future will become more and more clean and environmentally friendly. Therefore, many countries in the world, including China, are vigorously supporting the development of electric vehicle technology.

The vast majority of traditional cars use a vacuum-assisted servo braking system, which allows both manpower and power to participate in braking, which can reduce the burden on the driver and improve driving comfort. The vacuum source of the vacuum booster of the braking system of a traditional internal combustion engine car comes from the engine intake manifold, and the vacuum negative pressure can generally reach 0.05-0.07MPa. For pure electric vehicles or fuel cell vehicles, after the engine assembly is removed, the braking system loses its vacuum boosting function due to the absence of a vacuum power source, and the braking force generated by manpower alone cannot meet the needs of service braking. The vacuum booster device of the dynamic system is modified. On some electric vehicles, an electric vacuum pump is added between the pedal and the master cylinder to generate the negative pressure required for power assist. Although the power assist problem can be solved, the electric vacuum booster pump is large in size, difficult to arrange, and the control effect is not ideal. . Therefore, for electric vehicles, it is a very necessary thing to develop a new power-assisted braking system suitable for electric vehicles.

The hydraulic braking system has experienced decades of development, and it is now a stable braking system. It is a reliable method to use hydraulic pressure for power-assisted braking on electric vehicles. Now some institutions have developed some hydraulic power-assisted braking systems, more typical accumulator-type hydraulic power-assisted braking systems and plunger pump-type hydraulic power-assisted braking systems. The accumulator-type power-assisted braking system needs to use a high-speed on-off valve, which makes it more difficult to control, and the internal pressure of the accumulator fluctuates greatly during continuous boosting, and the cost of the on-off valve is relatively high. In the plunger pump hydraulic power-assisted braking system, the plunger pump directly assists, the control accuracy is low, the booster response is slow, and high-speed switching valves are also required, and the driver's feeling and comfort are poor.

At present, some research units have done some research on hydraulic power-assisted braking systems. Generally speaking, there are two main schemes for the current hydraulic power-assisted braking system: the hydraulic power-assisted braking system based on the accumulator and the hydraulic power-assisted braking system based on the plunger pump.

For example, the Chinese Patent No. 200510115432.8 is an invention patent of "a hydraulic power-assisted braking system". The electronic control unit is electrically connected with the high pressure switch and the oil pump assembly respectively, and the oil pump assembly is respectively connected with the oil pot and the accumulator. When the pressure in the accumulator is lower than a certain value, the oil pump assembly is opened to supply oil to the accumulator for pressurization, and when the pressure reaches a certain value, the oil pump assembly stops working. The electronic control unit controls the power boost of the master cylinder by controlling the opening and closing of the on-off valve. The patent adopts the on-off valve structure, which makes it difficult to control, and the fluctuation of the internal pressure of the accumulator during continuous boosting will also have a great impact on the boosting effect and pedal feel.

Another example is the Chinese Patent No. 201320439577.3 "an auxiliary brake device" utility model patent. The auxiliary brake device includes a pedal simulator, an electronic control unit, and a master cylinder hydraulic adjustment unit. Pumps and switching valves, etc. When braking, the plunger pump is turned on to pressurize the front chamber of the master cylinder to provide power assistance; when the brake is stopped, the switch valve in the front chamber is opened to release the pressure, and the piston of the master cylinder returns under the action of the return spring. This patent uses a plunger pump to directly assist, and the boost response is slow. In the case of failure, since the front chamber of the master cylinder is not directly connected to the oil cup, it will be difficult to replenish fluid during braking.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the problems existing in the prior art, and to provide a new type of hydraulic power-assisted braking system with no switch valve structure, fast boosting speed, backup for failure and good pedal feeling; especially for electric The utility model provides a hydraulic power-assisted braking system with simple structure and reliable performance.

In order to solve the above-mentioned technical problems, the present invention is realized by adopting the following technical solutions, which are described as follows in conjunction with the accompanying drawings:

A hydraulic power-assisted braking system, including an electronic control unit 1, a motor 2, a roller screw mechanism 3, a booster cylinder 4, a rotation angle sensor 5, an oil cup 6, a three-chamber brake master cylinder 7, a brake pedal 8 and a pusher pole 9;

The electronic control unit 1 is connected to the motor 2;

The motor 2 is connected with the roller screw mechanism 3;

The roller screw mechanism 3 is rigidly connected with the booster cylinder piston 43 in the booster cylinder 4;

The booster cylinder 4 is connected with the three-chamber brake master cylinder 7 through an oil circuit;

The booster cylinder 4 is connected to the oil cup 6 through an oil circuit;

The brake pedal 8 is rigidly fastened to the push rod 9;

The push rod 9 is inserted into the three-chamber brake master cylinder 7;

The brake pedal 8 is connected to the rotation angle sensor 5;

The rotation angle sensor 5 is connected with the electronic control unit 1 .

The three-chamber brake master cylinder 7 described in the technical solution includes a master cylinder end cover 74, a master cylinder body 84, a master cylinder first piston 71 and a master cylinder second piston 77;

The master cylinder end cover 74 is fixedly connected with the master cylinder body 84, and a sealing ring 75 is arranged between the master cylinder end cover 74 and the master cylinder body 84;

The first piston 71 of the master cylinder and the second piston 77 of the master cylinder divide the three-chamber brake master cylinder 7 into the first chamber 85 of the three-chamber brake master cylinder, the second chamber 86 of the three-chamber brake master cylinder and the three-chamber brake master cylinder. Three chambers of the third cavity 87 of the moving master cylinder;

The first chamber 85 of the three-chamber brake master cylinder is provided with an oil inlet 79 in the first chamber of the three-chamber brake master cylinder;

The second cavity 86 of the three-chamber brake master cylinder is provided with a first oil inlet 76 and a first oil outlet 80;

The third chamber 87 of the three-chamber brake master cylinder is provided with a second oil inlet 78 and a second oil outlet 82 .

In the technical solution, the first cavity 85 of the three-chamber brake master cylinder is provided with a boss and a cylindrical plate 73 with holes; the push rod 9 is fixedly connected with the cylindrical plate 73 with holes, and inserted into the three-chamber brake In the first cavity 85 of the master cylinder; a sensory simulation spring 72 is provided between the boss and the cylindrical plate 73 with holes;

The second cavity 86 of the three-chamber brake master cylinder is provided with a first return spring 81;

The third cavity 87 of the three-chamber brake master cylinder is provided with a second return spring 83 .

The booster cylinder 4 described in the technical solution is provided with a liquid replenishment port 41, an oil return port 42 and a booster cylinder oil outlet 44;

The booster cylinder piston 43 divides the booster cylinder 4 into two chambers, the first cavity 45 of the booster cylinder and the second cavity 46 of the booster cylinder;

The booster cylinder oil outlet 44 is connected to the first cavity oil inlet 79 on the three-chamber brake master cylinder 7 through an oil circuit;

The liquid replenishment port 41 and the oil return port 42 are directly connected to the oil cup 6 through an oil passage.

In the technical solution, the initial position of the booster cylinder piston 43 is between the liquid replenishment port 41 and the oil return port 42, and the distance from the oil return port 42 is less than 1 mm.

In the technical solution, the first oil inlet 76 and the second oil inlet 78 are respectively connected to the oil cup 6, and the first oil outlet 80 and the second oil outlet 82 are respectively connected to the pipeline IA1, IIA2 and The wheel cylinders are connected.

In the technical solution, there is a distance between the first piston 71 of the master cylinder and the end of the push rod 9 .

The working principle of the hydraulic power-assisted braking system of the present invention is: during normal braking, when the driver steps on the brake pedal 8, the angle sensor 5 automatically collects the driver's braking intention and transmits it to the electronic control unit 1, The electronic control unit 1 controls the rotation of the motor 2 according to the driver's braking intention, converts the rotational motion into a forward motion through the roller screw mechanism 3, and pushes the piston 43 of the booster cylinder to move forward, and the liquid replenishment port 41 can be supplied to the second cylinder of the booster cylinder at any time. One cavity 45 replenishes fluid. When the booster cylinder piston 43 just starts to move forward, the oil return port 42 is not yet closed, but the distance between the initial position of the booster cylinder piston 43 and the oil return port 42 is very short, and the oil return port 42 is quickly closed by the piston. 43 is closed, after sealing, a sealed space is formed between the second cavity 46 of the booster cylinder and the first cavity 85 of the three-chamber brake master cylinder, and oil pressure can be established. When the piston 43 of the booster cylinder continues to move, the system in the hydraulic booster cylinder 4 The dynamic fluid enters the first cavity 46 of the three-chamber brake master cylinder through the pipeline, pressurizes it, and pushes the first piston 71 and the second piston 77 of the master cylinder to move forward, thereby realizing power-assisted braking. At the beginning of braking, because there is a certain gap between the push rod 9 and the first piston 71 of the master cylinder, manpower only provides the wire control signal, and does not directly participate in the power assist. Continue to step on the brake pedal 8, so that the push rod 9 overcomes the gap and contacts the first piston 71 of the master cylinder. At this time, manpower also joins in to push the first piston 71 of the master cylinder to move forward, and together with the motor 2, it provides power for braking. . On the contrary, when the driver stops braking, the electronic control unit 1 can control the reverse rotation of the motor 2 according to the driver's intention, so that the piston 43 of the booster cylinder moves backward, so that the second cavity 46 of the booster cylinder is connected with the first cavity of the three-chamber brake master cylinder. The oil pressure in the closed space formed between the cavities 85 decreases, the first piston 71 and the second piston 77 of the master cylinder will gradually return to their positions under the action of the return spring, and the push rod 9 will also return to the original position under the action of the sensory simulation spring 72. In the initial position, when the booster cylinder piston 43 passes over the oil return port, the closed space is connected to the oil cup, and the oil pressure disappears. When the booster cylinder piston 43 continues to return, the oil return port 42 will automatically replenish the second chamber 46 of the booster cylinder. Until the booster cylinder piston 43 returns to the initial position.

The principle of the pedal feeling simulation of the hydraulic power-assisted braking system of the present invention is as follows: Referring to Fig. The cylindrical flat plate 73 with holes is tightly connected, and there are two openings on the periphery of the cylindrical flat plate 73 with holes. There is a feeling simulation spring 72 between the cylindrical flat plate 73 with holes and the protrusion in the middle of the master cylinder 7 to provide the driver with a pedal. Feel analog. When the driver stepped on the pedal 8, the push rod 9 would move forward, and the holed cylinder plate 73 would also move forward thereupon, feeling that the simulated spring 72 would be compressed at the same time, producing a reaction force, acting on the holed cylinder On the plate 73, and then transmitted to the brake pedal 8, so that the driver can feel a feedback force. Since this active force has a linear relationship with the stroke of the pedal 8, a good pedal feeling can be produced for the driver, and the pedal feeling simulation function can be realized. When the driver stops braking, under the action of the sensory simulation spring 72, the brake pedal 8 can also return automatically.

The failure backup working principle of the hydraulic power-assisted braking system provided by the present invention is: when the power-assisted mechanism breaks down, the driver depresses the brake pedal 8 and can also push the push rod 9 to move forward to overcome the push rod 9 and the first piston 71. After the gap, push the first piston 71 of the master cylinder to move forward to realize backup braking; meanwhile, the liquid return port 42 of the booster cylinder is connected with the oil cup 6, and the second cavity 46 of the booster cylinder is also very easy to replenish and return liquid. When the pedal 8 is loosened, the simulated spring 72 can also make the pedal 8 return to its original position.

Compared with prior art, the beneficial effects of the present invention are:

The hydraulic power-assisted braking system of the present invention directly adopts the structure of the motor lead screw, which converts the rotational motion of the motor into the translational motion of the piston, which is convenient and flexible to control, and cancels the switching solenoid valve. The structure is simple and the pressurization response is fast.

The hydraulic power-assisted braking system of the present invention can also play a role of manpower in the case of failure to perform effective manpower braking, has a good failure backup function, and ensures the safety of braking in extreme situations.

The hydraulic power-assisted braking system of the present invention uses a compressed spring to simulate the pedal feeling, and can provide the driver with a good pedal feeling.

In the hydraulic power-assisted braking system of the present invention, the pedal is directly connected to the main cylinder, which is less modified than the traditional mechanism, and the electric cylinder is connected to the main cylinder through pipelines, which can be freely arranged on the whole vehicle and has a flexible structure.

The invention can realize the effect of small-stroke wire-controlled large-stroke boosting, and can be easily refitted into a braking device with an energy recovery system.

Description of drawings

Below in conjunction with accompanying drawing, the present invention will be further described:

Fig. 1 is a schematic structural diagram of a hydraulic power-assisted braking system according to the present invention;

Figure 2 is a schematic diagram of the internal push rod connection structure of the three-chamber brake master cylinder;

In the picture:

1-Electronic control unit; 2-Motor; 3-Roller screw mechanism; 4-Boost cylinder; 41-Refill port; 42-Oil return port; 43-Piston of power cylinder; The first cavity of the booster cylinder; 46-the second cavity of the booster cylinder; 5-rotation angle sensor; 6-oil cup;

7-three-chamber brake master cylinder; 71-first piston of master cylinder; 72-feeling simulation spring; 73-cylindrical plate with holes; 74-end cover of master cylinder; 75-sealing ring; 76-first oil inlet ; 77 the second piston of the master cylinder; 78-the second oil inlet; 79-the first chamber oil inlet of the three-chamber brake master cylinder; 80-the first oil outlet; 81-the first return spring; 82-the first Two oil outlets; 83-Second return spring; 84-Master cylinder block; 85-First chamber of three-chamber brake master cylinder; 86-Second chamber of three-chamber brake master cylinder; 87-Three-chamber brake The third chamber of the master cylinder; 8-brake pedal; 9-push rod; A1-pipeline Ⅰ; A2-pipeline Ⅱ

detailed description

The present invention is described in detail below in conjunction with accompanying drawing:

The hydraulic power-assisted braking system provided by the present invention includes an electronic control unit 1, a motor 2, a roller screw mechanism 3, a booster cylinder 4, a rotation angle sensor 5, an oil cup 6, a three-chamber brake master cylinder 7, and a sensory simulation spring 72 , Cylindrical plate 73 with holes, brake pedal 8, push rod 9 etc. The brake pedal 8 is rigidly connected with the push rod 9, and the push rod 9 is inserted into the first cavity 85 of the three-chamber brake master cylinder through the through hole of the master cylinder end cover 74, and the push rod 9 and the cylindrical plate 73 with holes Tightly connected, there are two openings on both sides of the cylindrical plate 73 with holes, which are used to keep the same oil pressure on both sides of the plate, so that the push rod can move normally. There is a feeling simulation spring 72 between the cylinder plate 73 with holes and the protrusion in the middle of the master cylinder, to provide the driver with pedal feeling simulation. The piston 43 of the booster cylinder is rigidly connected with the roller screw mechanism 3, the oil outlet 44 of the booster cylinder is connected to the oil inlet 79 of the first cavity of the three-chamber brake master cylinder through the oil circuit, and the liquid replenishment port 41 and the oil return port 42 are connected through the oil circuit It is directly connected with the oil cup 6, and the initial position of the booster cylinder piston 43 is between the liquid replenishment port 41 and the oil return port 42, and the distance from the oil return port 42 is very close, about 1 mm. The oil cup 6 is respectively connected with the first oil inlet 76 and the second oil inlet 78 of the master cylinder, and the first oil outlet 80 and the second oil outlet 82 are respectively connected with the wheel cylinder through the pipelines A1 and A2.

The hydraulic power-assisted braking system provided by the present invention has two working modes: normal braking mode and backup braking mode.

In normal braking mode, when the driver steps on the brake pedal 8, the angle sensor 5 automatically collects the driver's braking intention and transmits it to the electronic control unit 1, and the electronic control unit 1 controls the motor according to the driver's braking intention. 2 to rotate, the rotary motion is converted into forward motion through the roller screw structure 3, and the booster cylinder piston 43 is pushed forward, and the liquid replenishment port 41 can replenish fluid to the first chamber 45 of the booster cylinder at any time. When the booster cylinder piston 43 just starts to When moving forward, the oil return port 42 has not been closed, but the distance between the initial position of the booster cylinder piston 43 and the oil return port 42 is very short, and the oil return port 42 is quickly closed by the piston. A closed space is formed between the first chamber 85 of the brake master cylinder, and oil pressure can be established. When the piston 43 of the booster cylinder continues to move, the brake fluid in the second chamber 46 of the booster cylinder enters the three-chamber brake through the pipeline. The first chamber 85 of the master cylinder is pressurized to push the first piston 71 of the master cylinder and the second piston 77 of the master cylinder to move forward, thereby realizing power-assisted braking. When just starting to brake, because there is a gap between the push rod 9 and the first piston 71 of the master cylinder, the manpower only provides the wire control signal and does not participate in power assistance. Continue to step on the brake pedal 8, so that the push rod 9 overcomes the gap and contacts the first piston 71 of the master cylinder. At this time, manpower also joins the brake system, and together with the motor 2, the three-chamber brake master cylinder 7 provides boost. On the contrary, when the driver stops braking, the electronic control unit 1 can control the reverse rotation of the motor 2 according to the driver's intention, so that the booster cylinder 4 moves backward, and the volume of the second cavity 46 of the booster cylinder becomes larger, so that the second cavity 46 of the booster cylinder The volume of the closed space formed between the first chamber 85 of the three-chamber brake master cylinder increases, and the oil pressure decreases. Under the action of the return spring 83, it will gradually return to its original position, and the brake pedal 8 will also return to its original position under the action of the sensory simulation spring 72. When the booster cylinder piston 43 moves backward and crosses the oil return port, the previously formed closed space Connect with the oil cup 6 through the oil return port 42, and the oil pressure disappears. When the booster cylinder piston 43 continues to return, the oil return port 42 will automatically replenish fluid to the second chamber 46 of the booster cylinder until the booster cylinder piston 43 returns to the initial position.

When the motor 2 fails and cannot move, the backup braking mode is automatically turned on. The driver depresses the brake pedal 8 and can also push the push rod 9 to move forward. When the push rod 9 overcomes the gap with the first piston 71 of the master cylinder, it directly contacts the first piston 71 of the master cylinder and can push the first piston 71 of the master cylinder. The piston 71 and the second piston 77 of the master cylinder move forward, and the manual braking can be carried out smoothly to realize backup braking; It is also very easy to connect, refill and return liquid. This mode ensures effective braking under fault conditions and provides a guarantee for the safety of the vehicle.

The internal structure of the three-chamber brake master cylinder 7 is a focus of this patent. The internal structure of the three-chamber brake master cylinder 7 will be described in detail below in conjunction with FIG. 2 . As shown in Figure 2, the system includes a first piston 71 of the master cylinder, a feeling simulation spring 72, a cylindrical plate 73 with holes, an end cover 74 of the master cylinder, a sealing ring 75, a first oil inlet 76, a second piston 77 of the master cylinder, The second oil inlet 78, the first cavity oil inlet 79 of the three-chamber brake master cylinder, the first oil outlet 80, the first return spring 81, the second oil outlet 82, the second return spring 83, the main Cylinder block 84, three-chamber brake master cylinder first chamber 85, three-chamber brake master cylinder second chamber 86, three-chamber brake master cylinder third chamber 87, push rod 9, etc. The three-chamber brake master cylinder 7 is a three-chamber master cylinder. The second chamber 86 and the third chamber 87 of the three-chamber brake master cylinder are basically the same as the traditional two-chamber series master cylinder. Here we focus on the inside of the first chamber. structure. The push rod 9 extends into the first chamber through a well-sealed master cylinder end cover 74, but there is a certain distance from the first piston 71 of the master cylinder. The master cylinder end cover 74 is threadedly connected to the master cylinder body 84, and a sealing ring 75 is arranged therebetween for sealing. The push rod 9 is fixedly connected with a cylindrical flat plate 73 with holes, and the two holes outside the cylindrical flat plate 73 with holes are used to keep the oil pressure on both sides the same, and the cylindrical flat plate 73 with holes plays a guiding role for the push rod 9 . There is a feeling simulation spring 72 between the cylindrical flat plate 73 with holes and the protrusion inside the three-chamber brake master cylinder 7. When the brake pedal 8 is stepped on, the push rod 9 moves forward, and the cylindrical flat plate 73 with holes Also along with the movement, the sensory simulation spring 72 between the holed cylindrical plate 73 and the protrusion is compressed, which can produce a good sensory simulation. Under the small stroke of the pedal, because there is a certain distance between the push rod 9 and the first piston 71 of the master cylinder, manpower does not directly provide power assist at this time, but only provides a signal of brake-by-wire. The active master cylinder 7 is assisted, and the function of small stroke wire control can be realized. When the push rod 9 moves a certain distance and contacts the first piston 71 of the master cylinder, manpower will also directly provide power assistance to realize the human power assistance effect.

Claims (3)

1. a kind of braking system with hydraulic assisting force, it is characterised in that：

Including electronic control unit (1), motor (2), roller screw mechanism (3), servo-cylinder (4), rotary angle transmitter (5), lubricating cup (6), three chamber master cylinders (7), brake pedal (8) and push rod (9)；

The electronic control unit (1) is connected with motor (2)；

The motor (2) is connected with roller screw mechanism (3)；

The roller screw mechanism (3) is rigidly connected with the servo-cylinder piston (43) in servo-cylinder (4)；

The servo-cylinder (4) is connected by oil circuit with three chamber master cylinders (7)；

The servo-cylinder (4) is connected by oil circuit with lubricating cup (6)；

The brake pedal (8) is rigidly fastenedly connected with the push rod (9)；

The push rod (9) is inserted into three chamber master cylinders (7)；

The brake pedal (8) is connected with the rotary angle transmitter (5)；

The rotary angle transmitter (5) is connected with the electronic control unit (1)；

The three chambers master cylinder (7) includes master cylinder end cap (74), master cylinder body (84), master cylinder first piston (71) and master cylinder the Two pistons (77)；

The master cylinder end cap (74) is fixedly connected with master cylinder body (84), is provided between master cylinder end cap (74) and master cylinder body (84) Sealing ring (75)；

Three chamber master cylinders (7) are separated into three chamber master cylinders by the master cylinder first piston (71) and master cylinder second piston (77) First chamber (85), three the second chambers of chamber master cylinder (86) and three chamber master cylinders (87) three chambers of the 3rd chamber；

The first chamber of the three chambers master cylinder (85) is provided with three chamber master cylinder the first chamber oil inlets (79)；

The second chamber of the three chambers master cylinder (86) is provided with the first oil inlet (76) and the first oil-out (80)；

The chamber (87) of three chambers master cylinder the 3rd is provided with the second oil inlet (78) and the second oil-out (82)；

Boss and cylinder flat board (73) with holes are provided with the first chamber of the three chambers master cylinder (85)；The push rod (9) and band The cylinder flat board (73) in hole is fixedly connected, and is inserted into three the first chambers of chamber master cylinder (85)；In boss and cylinder with holes Provided with sensation simulation spring (72) between flat board (73)；Between being provided between the master cylinder first piston (71) and push rod (9) end Away from；

The first return spring (81) is provided with the second chamber of the three chambers master cylinder (86)；

The second return spring (83) is provided with the chamber (87) of three chambers master cylinder the 3rd；

The servo-cylinder (4) is provided with fluid infusion (41), oil return opening (42) and servo-cylinder oil-out (44)；

Servo-cylinder (4) is separated into the chamber of servo-cylinder first (45) and (46) two, the second chamber of servo-cylinder by the servo-cylinder piston (43) Chamber；

The servo-cylinder oil-out (44) is connected by oil circuit with the first chamber oil inlet (79) on three chamber master cylinders (7)；

The fluid infusion (41) and oil return opening (42) are joined directly together by oil circuit with lubricating cup (6).

2. a kind of braking system with hydraulic assisting force according to claim 1, it is characterised in that：

The initial position of the servo-cylinder piston (43) between fluid infusion (41) and oil return opening (42), with oil return opening (42) away from From less than 1mm.

3. a kind of braking system with hydraulic assisting force according to claim 1, it is characterised in that：

First oil inlet (76) and the second oil inlet (78) are connected with lubricating cup (6) respectively, first oil-out (80) and Second oil-out (82) is connected by pipeline I (A1), pipeline II (A2) with wheel cylinder respectively.