JPH0624914B2 - Braking pressure generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention includes a master cylinder that supplies pressure to a wheel brake, and a hydraulic booster connected to the master cylinder. The master cylinder is a hydraulic booster. The present invention relates to a braking pressure generating device used in a hydraulic brake system of an automobile having a central valve that disconnects a connection between a pressure chamber of a master cylinder and a non-pressurized reservoir according to a pressure in a booster chamber.

[Prior Art and Problems Thereof] Generally, a braking pressure generating device of this type has a central valve arranged in a master cylinder. The central valve closes after the booster piston has traveled a predetermined distance, thereby blocking communication between the pressure chamber of the master cylinder and the unpressurized supply reservoir. When the booster piston further moves, the master cylinder piston arranged in the master cylinder also moves, forming a pressure corresponding to the pressure chamber of the master cylinder, and the braking pressure is transmitted to the wheel brake connected to this pressure chamber. .

In order to move the booster piston, it is necessary to create the required pressure in the booster chamber of the hydraulic booster. The movement of the booster piston requires a relatively high pressure, for example between 6 and 8 bar, because the sealing member surrounding the booster piston rubs against the inner wall of the booster chamber. However, in order to create such pressure in the booster chamber, the brake pedal must be moved a required distance in the actuating direction. Therefore, the distance that the brake pedal moves before the pressure is formed in the booster chamber is the idling distance of the brake pedal, and the braking action can be performed after moving the idling distance.

The present invention is directed to a vehicle that can close the central valve with a small pressure in the booster chamber of the hydraulic booster and with a small travel distance of the brake pedal, and can minimize the aerial distance of the brake pedal during deceleration of the vehicle. An object of the present invention is to provide a braking pressure generator for a hydraulic brake system.

[Means, Actions and Effects for Solving the Problems] According to the present invention for achieving the above object, a pressure chamber connected to a wheel brake is defined in an inner hole of a housing, and pressure is generated by moving in the inner hole. A master cylinder having a master cylinder piston that forms a braking pressure inside the chamber, a booster chamber that forms a pressure corresponding to the moving distance of the brake pedal, and a filling chamber that communicates with the non-pressurized reservoir are partitioned, and act from one end side. The other end of the booster chamber facing the filling chamber by the pressure of the booster chamber has a hydraulic booster having a booster piston that presses the master cylinder piston, and is guided in an axial guide hole formed in the booster piston. An intermediate piston that receives the pressure in the booster chamber on its end face and receives the pressure in the filling chamber on the other end face.
A central valve that is controlled by the intermediate piston to communicate and block between the pressure chamber and the filling chamber, and the central valve is a closing member supported by a return spring that biases the master cylinder piston to an initial position. And a valve seat formed on the other end side of the working piston, one end side of which is guided in the axial through hole of the master cylinder piston and abuts on the intermediate piston, and a braking pressure generation device for a hydraulic brake device of an automobile. Will be provided.

In this braking pressure generating device, when the brake pedal is operated, a pressure corresponding to the moving distance of the brake pedal is formed in the booster chamber of the hydraulic booster. The pressure in the booster chamber is small at first, and acts on one end side of the booster piston and also acts on the end face on one end side of the intermediate piston. At this time, since the braking pressure is not formed in the pressure chamber of the master cylinder, the pressure does not act on the end surface on the other end side where the valve seat of the working piston is formed, while the master cylinder piston has a relatively strong return spring. The booster piston is insufficient to move because it is biased at. Therefore, the working piston moves at a low booster chamber pressure that is insufficient for moving the booster piston in the initial operation stage of the hydraulic booster to bring the valve seat into contact with the closing member, thereby closing the central valve. Further, when the pressure in the booster chamber rises, the working piston and the booster piston are moved by the pressure in the booster chamber with the central valve closed, so that the braking pressure is immediately formed in the pressure chamber of the master cylinder.

Therefore, according to the braking pressure generator of the present invention, the central valve is immediately closed when the brake pedal slightly moves and a slight pressure is formed in the booster chamber of the hydraulic booster.
The aerial distance of the brake pedal can be minimized.

In a preferred embodiment of the present invention, the intermediate piston is formed to have an effective area larger than that of the booster piston by being urged toward the other end side by receiving the pressure in the booster chamber. In this case, since the intermediate piston receives a larger force than the booster piston, the intermediate piston does not move the actuating member and the closing member against the return spring of the master cylinder piston while the central valve is closed before the booster piston moves. And moves to form a braking pressure in the pressure chamber of the master cylinder. At this time, it is preferable to form a braking pressure in the pressure chamber of the master cylinder such that the brake pad is brought into contact with the brake disc or the brake drum.

If the movement range of the intermediate piston is limited by the master cylinder piston on the other end side, the intermediate piston is preferable because it can move together with the booster piston after contacting the master cylinder piston.

The moving distance until the closing member forming the central valve and the valve seat of the working piston contact each other is less than the maximum stroke of the intermediate piston, or the intermediate piston contacts the closing member of the central valve with the valve seat of the working piston. When the working piston is moved in the contact state to reduce the volume of the pressure chamber to form the braking pressure, the working piston is closed after the central valve is closed at a stage where the pressure in the booster chamber is relatively low. A certain amount of braking pressure can be formed in the pressure chamber of the master cylinder by the movement of.

The guide hole is formed as a bottomed hole having a bottom wall formed on the booster chamber side, and a passage that connects the working chamber formed by the bottom wall and the end face on one end side of the intermediate piston to the booster chamber is formed on the bottom. If formed on the wall, the booster piston and the intermediate piston can be formed in a simple structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Embodiment] A hydraulic booster 1 shown in FIG.
It is actuated by an actuating force via the pressure rod 3 connected to the brake pedal 2. When the brake pedal 2 is depressed, the piston rod 5 moves inside the booster piston 4, and the brake valve (not shown) causes the hydraulic booster 1 to move.
A pressure corresponding to the amount of depression of the brake pedal 2 is formed in the booster chamber 6.

The booster piston 4 is partitioned from the booster chamber 6 and a filling chamber that communicates with the non-pressurized reservoir 17 for supplying the working fluid. A bottom wall is arranged on one end side facing the booster chamber 6 and the booster piston 4 faces the filling chamber. It has a blind hole-shaped guide hole 7 having an open end. In the guide hole 7, the intermediate piston 8 is guided between the bottom wall and the stopper 20 arranged on the opening end side in a sealed state. The working chamber defined in the guide hole 7 by the end face of the intermediate piston 8 near the booster chamber 6 on the one end side communicates with the booster chamber 6 of the hydraulic booster 1 through the passages 9 and 10 and faces the filling chamber. The atmospheric pressure of the non-pressurized reservoir 17 acts on the end surface of the intermediate piston 8 on the other end side. Further, the intermediate piston 8 is formed such that the effective area on which the pressure of the booster chamber 6, that is, the working chamber defined in the guide hole 7, acts is larger than that of the booster piston 4.

A master cylinder 11 is connected to the hydraulic booster 1. When the booster piston 4 moves in the braking operation direction to the left in FIG. 1 due to the pressure in the booster chamber 6, the master cylinder piston 12 of the master cylinder 11 moves against the biasing force of the return spring of the master cylinder 11. can do. The master cylinder piston 12 has an axial through hole 13 formed therein, and the working piston 14 forming a central valve together with the closing member 15 has an axial through hole 13 formed therein.
You will be guided inside. One end of the working piston 14 abuts on the intermediate piston 8 via a rod portion 18 projecting to the hydraulic booster 1 side, and the master cylinder 11 is provided on the other end side end face.
The pressure in the pressure chamber 16 acts on the pressure chamber 16.

The working piston 14 has a radial hole and a longitudinal hole, and a recess is formed on the end face where the longitudinal hole opens. A rubber ring-shaped seal member that forms the valve seat of the central valve is inserted into this recess, and the working piston 1
When 4 is moved to the left in the figure by the intermediate piston 8 via the rod portion 18, the ring-shaped sealing member, that is, the valve seat is brought into contact with the closing member 15, and this central valve can be closed. Through this central valve, the pressure chamber 16 of the master cylinder 11 and the non-pressurized supply reservoir 17 are connected or disconnected. The closing member 15 of the central valve is
It is formed in such a size that the pressure fluid can freely flow between the longitudinal hole of the working piston 14 and the spherical portion of the closing member 15, and a plurality of grooves or notches along the longitudinal direction are formed on the outer peripheral surface of the closing member 15. Are preferably formed.

Next, the operation of the braking pressure generator will be described.

With the brake pedal 2 released, the hydraulic booster 1
The respective members of the master cylinder 11 are arranged at the positions shown in FIG. 1, and the pressure chamber 16 of the master cylinder 11 communicates with the supply reservoir 17 via the central valve in the open position.

When the brake pedal 2 is stepped on, the pedaling force acting on the brake pedal 2 is applied via the pressure rod 3 to the piston rod 5
And the piston rod 5 moves. As a result, a brake valve (not shown) is actuated, and the booster chamber 6 of the hydraulic booster 1 is pressurized by the hydraulic pressure supplied via this brake valve. The pressure formed in the booster chamber 6 of the hydraulic booster 1 is also transmitted to the guide hole 7 of the booster piston 4 through the passages 10 and 9, and acts on the end face of the intermediate piston 8 on the booster chamber 6 side.

Since the intermediate piston 8 has a larger effective area than the booster piston 4, a force larger than that acting on the booster piston 4 acts in the braking operation direction. Further, since the pressure chamber 16 communicates with the supply reservoir 17 via the central valve, the intermediate piston 8 is urged toward the brake pedal 2 via the rod portion 18 on the end face of the working piston 14 on the pressure chamber 16 side. However, the booster piston 4 is biased toward the brake pedal 2 by the return spring of the master cylinder 11 via the master cylinder piston 12. Therefore, the intermediate piston 8 starts moving when the pressure transmitted to the guide hole 7 is relatively low.

When the intermediate piston 8 moves in the braking direction,
The actuating piston 14 that contacts the intermediate piston 8 via the rod portion 18 also moves. As a result, the working piston 14
The valve seat abuts the closing member 15 and shuts off the communication between the pressure chamber 16 of the master cylinder 11 and the non-pressurized supply reservoir 17.

When the pressure in the booster chamber 6 of the hydraulic booster 1 further rises, the intermediate piston 8 continues to move further in the brake operating direction, and the movement of the intermediate piston 8 causes the rod portion 18 to move the rod portion 18 while keeping the central valve closed. In the brake operating direction, a pressure travel is formed in the pressure chamber 16 of the master cylinder, and a corresponding braking pressure is also formed in the brake operating portion 19 of the wheel brake.

The movement distance of the intermediate piston 8 with respect to the booster piston 4 is limited by the stopper 20. When the intermediate piston 8 and the stopper 20 come into contact with each other, the brake operating portion 19
Preferably, the required amount of pressure is built up. After the intermediate piston 8 contacts the stopper 20, the hydraulic booster 1
When the pressure in the booster chamber 6 increases, the booster piston 4 also moves in the braking operation direction to move the master cylinder piston 12, and a braking pressure is formed in the pressure chamber 16 of the master cylinder 11 in a normal manner.

When the brake is released, the above operation is performed in reverse, and each member of the hydraulic booster 1 and the master cylinder 11 in the braking pressure generator returns to the position shown in FIG.

Therefore, the braking pressure generating device of the present embodiment is designed so that when the brake pedal 2 moves, the actuating piston is immediately activated before the booster piston 4 moves, that is, when a slight pressure is formed in the booster chamber 6 of the hydraulic booster. 14 moves to contact the closing member 15, and the pressure chamber 16 of the master cylinder
And the non-pressurized supply reservoir 17 are cut off, the central valve is closed, and the idling distance of the brake pedal 2 can be minimized.

[Brief description of drawings]

FIG. 1 is a sectional view of a braking pressure generator for a hydraulic brake system according to an embodiment of the present invention. 1 ... hydraulic booster, 2 ... brake pedal, 4 ... booster piston, 6 ... booster chamber, 7 ... guide hole,
8 ... Intermediate piston, 9, 10, 21 ... Passage, 11 ...
… Master cylinder, 12… Master cylinder piston,
13 ... axial through hole, 14 ... working piston, 15 ...
Closing member, 16, 22 ... Pressure chamber, 17 ... Supply reservoir, 18 ... Rod part, 19 ... Brake actuating part, 20
...... Stopper.

Claims (6)

[Claims] 1. A master cylinder piston which defines a pressure chamber (16) connected to a wheel brake in an inner hole of a housing and moves in the inner hole to form a braking pressure in the pressure chamber (16). Master cylinder (11) with 12)
And a booster chamber (6) that forms a pressure corresponding to the moving distance of the brake pedal (2) and a filling chamber that communicates with the non-pressurized reservoir (17), and the pressure of the booster chamber that acts from one end side. Thus, a hydraulic booster (1) having a booster piston (4) whose other end facing the filling chamber presses the master cylinder piston (12), and an axial guide hole (7) formed in the booster piston (4). ), An intermediate piston (8) which receives the pressure in the booster chamber (6) at its one end side in the axial direction and the pressure in the filling chamber at its other end side in the axial direction, and this intermediate piston (8) ) Controlled by the pressure chamber (1
6) and a central valve for connecting and disconnecting between the filling chamber and the filling chamber, the central valve supporting a closing member (1) supported by a return spring for urging the master cylinder piston (12) to an initial position.
5) and a valve seat formed on the other end side of the working piston (14) which is guided in the axial through hole (13) of the master cylinder piston (12) and has one end contacting the intermediate piston (8). And a braking pressure generating device for a hydraulic brake device of an automobile. 2. The effective area of the intermediate piston (8), which is urged toward the other end by receiving the pressure in the booster chamber (6), is larger than that of the booster piston (4). The braking pressure generating device according to claim 1. 3. The braking pressure generator according to claim 1 or 2, wherein the intermediate piston (8) has a movement range limited by the master cylinder piston (12) on the other end side. 4. The central valve according to claim 2, wherein the moving distance until the closing member (15) and the valve seat of the working piston (14) come into contact with each other is smaller than the maximum stroke of the intermediate piston (8). The braking pressure generating device according to item 3 or item 3. 5. The intermediate piston (8) moves the operating piston (14) in a state where the valve seat of the operating piston (14) is in contact with the closing member (15) of the central valve, so that the pressure chamber ( The braking pressure generating device according to any one of claims 2 to 4, wherein the braking pressure is formed by reducing the volume of (16, 22). 6. The guide hole (7) has a booster chamber (6).
Is formed by a bottomed hole having a bottom wall formed on the side thereof, and a working chamber formed by the bottom wall and the end face on one end side of the intermediate piston (8) communicates with the booster chamber (6). 1
The braking pressure generating device according to any one of claims 1 to 5, wherein 0) is formed on the bottom wall.