JPH0640323A - Negative pressure booster - Google Patents

Abstract

PURPOSE:To introduce air into an operation chamber with a high responsibility in rapid operation by providing an air in-take passage communicating the operation chamber in a valve cylinder and an air in-take valve which opens according to the advance of an input rod toward the valve cylinder to communicate the air intake passage to an air in-take port more than a specified value. CONSTITUTION:A valve cylinder 6 is provided with an air in-take passage 43 communicating the front end and an operation chamber RB along the axial direction of the valve cylinder 6. In the rear end of the air in-take passage 43, an air in-take valve 44 is provided, which opens according to the advance of an input rod 16 toward the valve cylinder 6 more than a specified value. In the case where sudden braking is performed by stepping a brake pedal 15, when the input rod 16 advances toward the valve cylinder 6 greater than the specified value, the air in-take valve 44 is opened, introducing the air from an air in-take port 8 to the operation chamber RB through the air in-take passage 43. Therefore, even if air flow resistance in a control valve 14, atmospheric pressure is quickly introduced to the operation chamber RB.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a rear extension cylinder having an air inlet at the rear end, which is provided at the rear of the booster shell.
A booster piston that divides the inside of the booster shell into a negative pressure chamber on the front side and a working chamber on the rear side is supported by the booster shell in an airtight and slidable manner while being surrounded by the rear extension cylinder and extending rearward. A valve cylinder is continuously provided in the valve cylinder, and the working chamber is switched between the negative pressure chamber and the atmosphere introduction port in accordance with the longitudinal movement of the input rod connected to the operating member and inserted into the valve cylinder. It relates to a negative pressure booster in which a control valve is arranged.

[0002]

2. Description of the Related Art Conventionally, such an apparatus has been disclosed in, for example, Japanese Patent Laid-Open No. Hei 2
It is already known, for example, in Japanese Patent No. 237861.

[0003]

In such a negative pressure booster, when the input rod is moved forward from its retracted limit position by the operating member, the control valve shuts off the communication between the negative pressure chamber and the working chamber and the working chamber is exposed to the atmosphere. By communicating with the inlet, the atmosphere is introduced into the working chamber, and as a result, the forward thrust is given to the booster piston by the pressure difference generated between the negative pressure chamber and the working chamber.

By the way, in the above-mentioned conventional negative pressure booster,
At the normal operating speed of the operating member, the output increases as the input increases, as shown by the solid line L _A in FIG. 4, but when the operating member is suddenly operated, it operates due to the air flow resistance in the control valve. Due to the restricted introduction of air into the chamber,
As shown by the broken line L _B ′ in FIG. 4, the increase in output is delayed, and a sufficient boost cannot be obtained.

The present invention has been made in view of the above circumstances, and is designed to ensure a sufficient boosting force by allowing the atmosphere to be introduced into the working chamber with high responsiveness when the operating member is rapidly operated. The purpose is to provide a pressure booster.

[0006]

In order to achieve the above object, according to the present invention, an atmosphere introducing passage communicating with a working chamber is provided in a valve cylinder, and an input rod is advanced relative to the valve cylinder by a predetermined value or more. And an atmosphere introduction valve which opens according to the above and communicates the atmosphere air introduction passage with the atmosphere introduction port.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, in FIG. 1, a master cylinder M operated by the booster B is attached to the front wall of the booster shell 1 of the negative pressure booster B.

The booster shell 1 is composed of a pair of front and rear shell halves 1a and 1b whose opposite ends are connected to each other, and a booster piston 2 is housed in the booster shell 1 so as to be reciprocally movable back and forth. On the rear surface of the booster piston 2, a diaphragm 4 whose outer circumference is sandwiched between the abutting portions of the shell halves 1a and 1b is superposed, and the inner circumference of the diaphragm 4 together with the inner circumference of the booster piston 2 is a piston boss. 5
Be combined with. Moreover the booster shell 1 by the booster piston 2 and the diaphragm 4 is partitioned and the negative pressure chamber R _A on the front side for exposing the front face of the booster piston 2, to the working chamber R _B on the rear side for exposing the rear surface of the diaphragm 4 It

A valve cylinder 6 is integrally projectingly provided at the rear end of the piston boss 5, and the valve cylinder 6 is projectingly provided at the center of the rear wall of the booster shell 1 to cover the valve cylinder 6 and A rear extension cylinder 7 having an atmosphere introduction port 8 in its part is supported by a bush 9 and a seal member 10 in an airtight and slidable manner.

A negative pressure introducing pipe 1 is provided on the front wall of the booster shell 1.
1 is connected in series, and the negative pressure chamber R _A is always connected via the negative pressure introducing pipe 11 to the intake manifold (not shown) of the internal combustion engine which is the negative pressure source.

The negative pressure chamber R _A communicates with the inside of the valve cylinder 6 through a first port 12 formed in the piston boss 5, and the working chamber R _B is a second port formed in the piston boss 5. It communicates with the inside of the valve cylinder 6 via 13. Therefore, the second port 13
The control valve 14 disposed in the valve cylinder 6 allows the first port 12
And the atmosphere introduction port 8 are alternately communicated with each other.

Referring also to FIG. 2, in the valve cylinder 6, an input rod 16 connected to a brake pedal 15 as an operating member.
And a control valve 14 operated by the input rod 16.
And are provided as follows. That is, a valve piston 17 is slidably fitted in the front portion of the valve cylinder 6, and the front end of the input rod 16 penetrating the atmosphere introduction port 8 swings through the ball joint 18 in the valve piston 17. Combined as possible. An annular first valve seat 20 is provided on the inner peripheral surface of the valve cylinder 6 so as to project, and an annular second valve seat 21 surrounded by the first valve seat 20 is formed on the rear end surface of the valve piston 17. Valve seat 20,
A valve body 22 cooperating with 21 is arranged in the valve cylinder 6. The valve body 22 is made of rubber and has a tubular shape with its front and rear ends open, and its rear end portion, that is, the base end portion 22 a is formed by a holding cylinder 23 fitted to the inner peripheral surface of the valve cylinder 6. 6 is held in close contact with the inner peripheral surface. The valve body 22 has the base end portion 2
2a, a thin flexible portion 22b bent inward in the radial direction,
And a thick valve portion 22 that is continuous with the front end of the flexible portion 22b.
c, and the valve portion 22c is arranged so as to face the first and second valve seats 20 and 21.

The valve portion 22c can be moved back and forth due to the deformation of the flexible portion 22b. The valve portion 22c is seated on the first and second valve seats 20 and 21 when moving forward, and is received by the front end of the holding cylinder 23 when moving backward. Moreover, an annular reinforcing plate 24 is embedded in the valve portion 22c, and a valve spring 25 for urging the valve portion 22c toward both valve seats 20 and 21 is provided between the reinforcing plate 24 and the input rod 16. Is reduced.

On the inner surface of the valve cylinder 6, one end of the first port 12 is outside the first valve seat 20, and the other is inside the valve seat 20.
One end of each port 13 is opened, and the inside of the second valve seat 21 communicates with the atmosphere introduction port 8 through the hollow portions of the valve body 22 and the holding cylinder 23.

In this way, the valve body 22, the valve spring 25, the first valve seat 20 and the second valve seat 21 constitute the control valve 14.

Between the input rod 16 and the holding cylinder 23, a return spring 26 for urging the input rod 16 toward the backward limit thereof is contracted.

At the rear end of the rear extension cylinder 7, an annular end wall 7a forming the atmosphere introduction port 8 is integrally formed.
A boss 29a of a stopper plate 29 that contacts the inner side surface of a and regulates the backward limit of the input rod 16 is screwed onto the input rod 16 so as to be adjustable in advance and retreat. Thus, if the stopper plate 29 is screwed or unscrewed, the screwing position between the stopper plate 29 and the input rod 16 is changed, so that the retracting limit of the input rod 16 can be adjusted back and forth. After the adjustment, the stopper plate 29 is fixed by tightening the lock nut 30, which is also screwed to the input rod 16. Moreover, the stopper plate 29 is provided with a plurality of ventilation holes 31 that are in constant communication with the atmosphere introduction port 8.

The valve cylinder 6 is provided with a control valve 14 from the air inlet 8.
An air filter 32 for filtering the air taken into the side is mounted around the input rod 16. This air filter 3
2 has an appropriate flexibility so as not to interfere with the relative displacement between the input rod 16 and the valve cylinder 6.

The piston boss 5 is provided with a large cylinder hole 33 opening at the center of the front surface thereof and a small cylinder hole 34 having both ends open inside the large cylinder hole 33 and the valve cylinder 6, and the small cylinder hole 34. A reaction force piston 35 which is integral with the valve piston 17 or abuts on the valve piston 17 is slidably fitted into the large cylinder hole 33, and an elastic piston 36 which faces the reaction force piston 35 is fitted into the large cylinder hole 33. At the same time, the output piston 37 that abuts the elastic piston 36 is slidably fitted. The output rod 37 has an output rod 3
8 is integrally projected, and the output rod 38 is a master cylinder M.
Is connected to the piston 39 of.

A synthetic resin retainer 41 is fitted and abutted on the front surface of the piston boss 5 in order to prevent the output piston 37 from falling out of the large-diameter cylinder hole 33. The retainer 41 and the booster shell 1 are connected to each other. The booster piston 2 is constantly urged in the backward direction, that is, toward the working chamber R _B by the return spring 40 that is contracted between the booster piston 2 and the front wall, and the backward limit of the booster piston 2 is formed by being raised to the rear surface of the diaphragm 4. The protrusion 4a thus formed is regulated by coming into contact with the inner surface of the rear wall of the booster shell 1.

The valve cylinder 6 is provided with an atmosphere introducing passage 43, the front end of which communicates with the working chamber R _B , along the axial direction of the valve cylinder 6. An atmosphere introducing valve 44 is provided that opens in response to the rod 16 moving forward with respect to the valve cylinder 6 by a predetermined value or more and connects the atmosphere introducing passage 43 to the atmosphere introducing port 8.

In FIG. 3, the atmosphere introducing valve 44 is a valve housing 45 which is press-fitted and fixed to the rear end of the atmosphere introducing passage 43.
And a valve body 47 which is housed in the valve housing 45 by closing the valve hole 46 provided at the rear end of the valve housing 45 through the atmosphere introduction port 8 and the valve body integrated with the valve body 47 A drive rod 48 that gently penetrates 46 and projects rearward, and a spring 4 that biases the valve body 47 in the valve closing direction.
9 and.

The valve housing 45 has an inward flange 45a having an insertion hole 50 formed at the inner peripheral edge at the front end, and an inward flange 4 having a valve hole 46 coaxial with the insertion hole 50 formed at the inner peripheral edge.
It is formed in a cylindrical shape having 5b at the rear end, and is press-fitted into the expanded diameter portion 43a provided at the rear end of the atmosphere introduction passage 43.

The drive rod 48 is so formed as to pass through the valve hole 46 and the insertion hole 50 and project rearward. A valve body 47 made of synthetic resin is seated on the inner surface of the inward flange 45b. Molded in the valve housing 45 to the middle of the drive rod 48 so that the valve hole 46 can be closed. The spring 49 surrounds the drive rod 48 and is compressed between the inward flange 45a and the valve body 47.
Due to the spring force of the spring 49, the drive rod 48 moves the valve body 4
7 is projected in the direction in which the inward facing flange 45b is seated, that is, rearward.

The valve housing 4 of the drive rod 48 with the valve body 47 seated on the inward flange 45b and the valve hole 46 closed.
The amount of protrusion from 5 to the rear side is determined by the input rod 16 with respect to the valve cylinder 6.
Is set to a backward limit position so that a predetermined distance d exists between the stopper plate 29 provided on the input rod 16 and the rear end of the drive rod 48.

According to such an atmosphere introduction valve 44, the valve element 47 closes the valve hole 46 by the spring force of the spring 49 when the input rod 16 is in the retracted limit position with respect to the valve cylinder 6. When the input rod 16 moves forward with respect to the valve cylinder 6 by the predetermined value d or more, the drive rod 48 is pushed by the stopper plate 29 to open the valve, and the atmosphere introduction port 8 communicates with the atmosphere introduction passage 43.

Next, the operation of this embodiment will be described. In the boosting rest state, as shown in FIGS. 1 and 2, the input rod 16 is located at the backward limit, and the control valve 14 has the valve portion 22c. The working chamber R _B is seated on the first and second valve seats 20 and 21, and the working chamber R _B is in a neutral state in which neither the negative pressure chamber R _A nor the air introduction port 8 is in communication. _A negative pressure of a negative pressure source supplied through the negative pressure introducing pipe 11 is stored in the chamber R _A , and a negative pressure appropriately diluted with the atmosphere in the working chamber R _B, that is, a pressure of the negative pressure chamber R _A. A slightly higher atmospheric pressure is maintained. In this way, a slight forward force is applied to the booster piston 2 due to the atmospheric pressure difference generated between the negative pressure chamber R _A and the working chamber R _B , but these forward force and the elastic force of the return spring 40 are balanced, and the booster piston 2 is boosted. The piston 2 is stopped at a position slightly advanced from the backward limit.

Now, the brake pedal 1 is used to brake the vehicle.
If 5 is stepped on and the input rod 16 and the valve piston 17 are moved forward, the booster piston 2 is initially immobile,
The second valve seat 21 is immediately separated from the valve portion 22c and the working chamber R _B
Is communicated with the air inlet 8. Moreover, the stopper plate 29
Moves away from the end wall 7a as the input rod 16 advances. As a result, the atmosphere enters the valve cylinder 6 through the air inlet 32 through the air filter 32, and the second valve seat 21 and the second port 1
3 is introduced into the working chamber R _B.

The working chamber R _B is introduced into the negative pressure chamber R _A by the introduction of the atmosphere.
When the pressure becomes higher than that, the booster piston 2 obtains a large forward thrust force based on the pressure difference between them and moves forward against the force of the return spring 40, and drives the piston 39 of the master cylinder M forward through the output rod 38. To do. Thus, the master cylinder M can be operated according to the depression of the brake pedal 15.

Assuming that the brake pedal 15 is suddenly depressed to perform a sudden braking operation, when the atmosphere is introduced from only the control valve 14 into the working chamber R _B , the air flow through the control valve 14 Since the resistance limits the introduction of the atmosphere into the working chamber R _B , the increase in output is delayed and a sufficient boost cannot be obtained, as indicated by the broken line L _B ′ in FIG. However, when the input rod 16 moves forward with respect to the valve cylinder 6 by the predetermined value d or more, the atmosphere introducing valve 44 opens and the atmosphere from the atmosphere introducing port 8 is introduced into the working chamber R _B through the atmosphere introducing passage 43. It
Therefore, even if the flow resistance in the control valve 14 is high, the working chamber R
The introduction of atmospheric pressure to _B will be carried out promptly,
It is possible to quickly increase the air pressure difference between the working chamber R _B and the negative pressure chamber R _A, as shown by the solid line L _B in FIG. 4, the response in comparison with the conventional one shown by the broken line L _B ' It is possible to improve the property and obtain a sufficient boost.

During the braking operation at the normal stepping speed, the booster piston 2 is moved forward by introducing the atmosphere from the control valve 14 into the working chamber R _B , so that the stopper plate 29 is provided at the rear end of the drive rod 48. There is no contact, and the atmosphere introduction valve 44 remains closed.

When the output of the output rod 38 exceeds the boosting limit point due to an increase in the pedaling force applied to the brake pedal 15, that is, the input of the input rod 16, the valve piston 17 brings its front surface into contact with the piston boss 5 and, therefore, the entire input. Is the valve piston 1
7, the piston boss 5, the elastic piston 36, and the output piston 37 are transmitted to the output rod 38, so that the sum of the forward force due to the atmospheric pressure difference of the booster piston 2 and the forward force due to the input is finally output from the output rod 38. Is output.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various small design changes can be made without departing from the present invention described in the claims. It is possible to

For example, the present invention can be implemented in connection with a tandem type negative pressure booster.

[0036]

As described above, according to the present invention, the atmosphere introducing passage communicating with the working chamber is provided in the valve cylinder and the atmosphere is opened when the input rod advances by a predetermined value or more with respect to the valve cylinder. Since the atmosphere introducing valve that connects the air introducing passage to the atmosphere introducing port is provided, it is possible to promptly introduce the atmosphere into the working chamber when the operation member is suddenly operated, and to secure a sufficient boosting power during the sudden operation.

[Brief description of drawings]

FIG. 1 is a vertical side view of a negative pressure booster.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an enlarged sectional view of part 3 in FIG.

FIG. 4 is an output characteristic diagram for an input.

[Explanation of symbols]

1 booster shell 2 booster piston 6 valve tube 7 rearward extension cylinder 8 air inlet 14 control valve 15 brake pedal 16 input rod 43 the air introducing passage 44 air introduction valve as an operation member B vacuum booster R _A working negative pressure chamber R _B Room

Claims (1)

[Claims] 1. A rear extension cylinder (7) having an air inlet (8) at a rear end thereof is provided at a rear portion of a booster shell (1), and the inside of the booster shell (1) has a negative pressure chamber on a front side ( R _a) and the rear working chamber (the booster piston (2) which divides the R _B) and, hermetically and with being surrounded extend rearward in the rear extension tube (7) in the booster shell (1) A valve cylinder (6) which is slidably supported is continuously provided, and an input rod (16) which is inserted into the valve cylinder (6) in a continuous manner with the operating member (15) is provided in the valve cylinder (6). in the vacuum booster which working chamber in response to the rearward movement (R _B) of the negative pressure chamber (R _a) and the air inlet (8) and the second communication switching control valve (14) is arranged, the valve cylinder (6 ) the working chamber (the air introduction passage communicating with the R _B) (43), the input rod (16) the valve cylinder (6)
A negative pressure, which is provided with an atmosphere introducing valve (44) which opens in response to advancing by a predetermined value or more to communicate the atmosphere introducing passage (43) with the atmosphere introducing port (8). booster.