JPH0952573A - Valve mechanism of booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate large output by a small booster by holding a valve mechanism in a non-operating condition, and operating the valve mechanism by operating an actuator through a slide member to dispense with a bellows provided in a constant pressure chamber, and to secure the effective area to which the negative pressure is applied. SOLUTION: When a brake pedal is stepped in the condition in which the atmosphere is introduced into a pressure chamber 59 of an actuator 41, a piston 53 is moved to the left through an input shaft 34, and communication of a constant pressure chamber with a variable pressure chamber is shut off by closing a vacuum valve 35, and an atmospheric valve 38 is opened to introduce the atmospheric pressure in the variable pressure chamber. The pressure difference is generated before and behind two power pistons to achieve the boosting effect. When the actuator 41 is operated and the negative pressure is introduced into a pressure chamber 59, a slide member 21 is retracted to the rear side by the pressure difference generated before and behind the piston 53 and a seal member 58, the vacuum valve 35 is closed and the atmospheric valve 38 is opened to similarly demonstrate the boosting effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a booster suitable for use in a vehicle brake, and more particularly to a booster having a function as an automatic brake.

[0002]

2. Description of the Related Art Conventionally, a bellows is provided in a constant pressure chamber formed in a shell, and negative pressure and atmospheric pressure can be selectively introduced into a variable pressure chamber through a space surrounded by the bellows. A brake booster configured as described above is known (for example, Japanese Patent Laid-Open No. 60-25840). In such a conventional device, a negative pressure is introduced into the bellows when the brake booster is inactive, and when necessary, the atmosphere is introduced into the bellows instead of the negative pressure to transform it. It can be introduced indoors. Therefore, when the atmosphere is introduced into the bellows, the brake booster can be operated without depressing the brake pedal, so that the function as an automatic brake can be obtained.

[0003]

However, in the above-mentioned booster, since the atmosphere is introduced into the bellows of the constant pressure chamber when operating as an automatic brake,
As a result, there is a drawback that the effective area between the constant pressure chamber and the variable pressure chamber on which a negative pressure acts is reduced and the output is reduced. In view of such circumstances, the present invention provides a valve mechanism for a booster that can prevent the effective area from decreasing and the output from decreasing.

[0004]

That is, according to the present invention, there is provided a valve body which is slidably provided in a shell and whose end portion is projected to the outside of the shell. A power piston that divides the constant pressure chamber and the variable pressure chamber into front and rear, a valve mechanism that is provided in the valve body to control the communication between the constant pressure chamber, the variable pressure chamber, and the atmosphere, and is interlocked with the valve plunger that constitutes this valve mechanism. In the booster equipped with an input shaft for operating the valve mechanism, the valve mechanism is provided with a tubular slide member which is slidably provided in the valve body while keeping airtightness, and the slide member A first valve seat provided, a second valve seat provided on the valve plunger, one end attached to the inner peripheral surface of the slide member, and the other end connected to the first valve seat and the second valve seat by an urging spring. Biased towards the valve seat A tubular valve element seated on each of the input shaft and the slide member, a return spring that biases the input shaft and the slide member in opposite directions to hold the valve mechanism in an inoperative state, and the input shaft and the slide member. It is characterized in that it is constituted by an actuator which is provided between the actuators and operates the valve mechanism by moving the slide member against the return spring.

[0005]

In the above structure, when the actuator is inactive and the valve mechanism is inactive, the pressure difference between the constant pressure chamber before and after the power piston and the variable pressure chamber is the same as in the conventionally known booster. Is maintained at zero so the booster is inactive. If the input shaft is advanced from this state and the valve mechanism is operated, the atmosphere is introduced into the variable pressure chamber and a pressure difference occurs between the constant pressure chamber before and after the power piston and the variable pressure chamber, so the booster boosts It comes to work.
However, when the actuator is operated while the valve mechanism is inactive, the actuator moves the slide member relative to the input shaft against the return spring. Even if is not advanced, the valve mechanism is activated, which causes the booster device to perform a boosting action. And in the present invention,
Since the bellows is not provided in the constant pressure chamber as in the conventional device described above, the effective area on which the negative pressure acts does not decrease, and therefore a sufficiently large output can be secured even with a small booster.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the illustrated embodiment. In FIG. Chamber 5 of 2
A substantially cylindrical valve body 6 is slidably passed through the shaft portions of the rear shell 2 and the center plate 3 by annular bearings 7 and 8, respectively, and is divided into chambers by annular seal members 10 and 11. It keeps airtight. The terminal tubular portion 6A of the valve body 6 is projected to the outside from the opening 2A of the rear shell 2, and the terminal tubular portion 6A is covered with a generally cylindrical dust cover 12 fitted in the opening 2A. The valve body 6 has a front power piston 14 and a rear power piston 1 housed in the front chamber 4 and the rear chamber 5, respectively.
5, and each power piston 1
Front diaphragm 16 and rear diaphragm 17 are respectively stretched on the rear surfaces of Nos. 4 and 15, constant pressure chamber A and variable pressure chamber B are provided in front and rear of front diaphragm 16, and constant pressure chamber C and variable pressure chamber D are also provided in front and rear of rear diaphragm 17, respectively. Is formed.

A valve mechanism 20 is provided in the valve body 6, and the valve mechanism 20 is, as shown in an enlarged view in FIG. 2, a tubular slide slidably provided in the terminal tubular portion 6A. A member 21, an annular first valve seat 22 formed in the front thick portion 21a of the slide member 21, and a valve slidably provided on the valve body 6 inside the annular first valve seat 22. An annular second valve seat 24 formed at the right end portion of the plunger 23 and the biasing spring 2 from the right side of FIG.
5 has a valve element 26 seated on both valve seats 22 and 24. An annular seal member 30 is provided on the outer peripheral surface of the slide member 21.
The airtightness between the slide member 21 and the end tubular portion 6A is maintained by the slide member 21, and the thick wall portion 21 of the slide member 21 is maintained.
The airtightness between the thick portion 21a and the annular protruding portion of the valve body 6 is maintained by the annular sealing member 31 provided on the inner peripheral surface of a. The valve body 26 is composed of a substantially cylindrical elastic body, and the attachment portion 26a at one end thereof is attached to the retainer 3
The slide member 21 is attached to the inner peripheral surface of the slide member 21 while keeping airtightness. The valve body 26 has a conventionally well-known configuration, and includes a curved portion 26b that extends inwardly in a radial direction in a central portion thereof, and the first valve seat 22 and the first valve seat 22 are provided at a tip portion of the curved portion 26b. A seating portion 26c that comes into contact with and separates from the second valve seat 24 is provided. Then, the biasing spring 25 is elastically mounted between the metal backup plate 33 embedded in the seating portion 26c of the valve body 26 and the step portion of the input shaft 34, and the seating portion 26c is supported by the biasing spring 25. It is biased toward the valve seats 22 and 24.

A seat portion 26 of the first valve seat 22 and the valve body 26.
A space outside the vacuum valve 35 formed by the seat portion of c and a constant pressure passage 21b formed by axially penetrating the thick portion 21a of the slide member 21 between the seal members 30 and 31. The constant pressure chamber A and the constant pressure chamber C are communicated with each other through the constant pressure passage 36 formed in the valve body 6. The constant pressure chamber A is connected to the intake manifold of the engine via a negative pressure introducing pipe 37 (FIG. 1) connected to the front shell 1. Further, inside the vacuum valve 35, an outer portion of the atmosphere valve 38 constituted by the seat portion of the second valve seat 24 and the seat portion 26c of the valve body 26, that is, an intermediate portion between the vacuum valve 35 and the atmosphere valve 38. The partial space is the variable pressure passage 39A formed in the valve body 6.
Is connected to the transformer room D via the
Is communicated with the variable pressure chamber B via a variable pressure passage 39B formed in the axial direction of the valve body 6. Further, the space inside the atmosphere valve 38 is provided with an atmosphere passage 40 formed inside the slide member 21 and an atmosphere passage 21c formed in the slide member 21 on the front side of an actuator 41 described later. A filter 42 is provided in the atmosphere passage 40, which is in communication with the atmosphere.

A return spring 44 is mounted between the step portion of the input shaft 34 and the retainer 32 attached to the slide member 21, and the return spring 44 allows the slide member 21 and the input shaft 34 to be connected to each other. Are urged in opposite directions, more specifically, the slide member 21 is urged to the left, and at the same time, the input shaft 34 and the valve plunger 2 are urged.
3 is urged to the right. And the slide member 21
Is biased to the left, the front end surface of the slide member 21 comes into contact with the valve body 6 and is held at that position. On the other hand, when the valve plunger 23 is urged to the right, it engages with the valve plunger 23 in a free state, that is, when the brake booster is in the backward movement operation in which the depression of the brake pedal is released. The key member 45 thus moved is moved to the right side together with the valve plunger 23, comes into contact with the valve body 6, and is held at that position. However, in the non-illustrated operating state, the key member 45 comes into contact with the inner surface of the rear shell 2 and its rightward movement is stopped, and the valve body 6 comes into contact with this key member 45 and its rightward movement is stopped. 45 is displaced to the advanced position relative to the valve body 6, so that the valve plunger 23 engaged with the key member 45 is also held in the advanced position relative to the valve body 6. ing. In this non-operating state, the valve body 26 is seated on the second valve seat 24 and closes the atmosphere valve 38, and the valve body 26 is attached to the first valve seat 22 by the relative advance of the valve plunger 23 described above. Although it is located in a close position, it is slightly separated from the first valve seat 22.
Therefore, in this non-operating state, the vacuum valve 35 is opened so that the variable pressure chambers B and D communicate with the constant pressure chambers A and C, and the constant pressure chambers A and C and the variable pressure chambers B and D are kept at the same pressure. You will be drunk.

Further, as shown in FIG. 1, a plate plunger 46 and a reaction disc 47 are sequentially arranged on the front side of the valve plunger 23, and the reaction disc 47 is fitted in the base portion of the output shaft 48. The tip end of the output shaft 48 is kept airtight from the front shell 1 via a seal member 50 and protrudes to the outside, and the tip end is interlocked with a piston of a master cylinder (not shown). Further, the valve body 6 is normally held in a non-actuated position by a return spring 51.

Next, the above-mentioned actuator 41 is shown in FIG.
As shown in FIG. 3, a piston 53 having a substantially disc shape attached to the input shaft 34 is provided, and the inner peripheral portion of the front end surface of the piston 53 is brought into contact with the step portion of the input shaft 34. The inner peripheral bead portion 54a of the diaphragm 54 is arranged on the rear side of the inner peripheral bead portion 54a.
By disposing the retainer 55 fixed to the input shaft 34 on the rear side, the retainer 55 is fixed to the input shaft 34 in an airtight manner. The rear end of the slide member 21 is integrally provided with a stepped tubular member 56, and the piston 53 is slidably loosely fitted in the large diameter portion of the stepped tubular member 56. . The outer peripheral bead portion 54b of the diaphragm 54 arranged on the rear side of the piston 53 is airtightly fixed to the large diameter portion of the stepped tubular member 56 by a retainer 57, and the front side of the stepped tubular member 56 is fixed. A seal member 58 is provided between the small-diameter portion on the side and the input shaft 34, and a pressure chamber 59 is formed between the seal member 58 and the piston 53. The pressure chamber 59 is connected to an electromagnetic flow path switching valve 61 (FIG. 1) via a conduit 60, and the flow path switching valve 61 allows either the atmospheric pressure or the negative pressure to flow into the pressure chamber 59. It can be supplied selectively.

In the above configuration, the actuator 4
In the state where the atmosphere is introduced into the first pressure chamber 59, since there is no pressure difference before and after the piston 53, the actuator 41 is in the inoperative state. When the brake pedal is released, the valve body 26 is seated on the second valve seat 24 and the atmosphere valve 38 is closed, as described above. Since the vacuum valve 35 is opened slightly away from the variable pressure chambers B and D, the variable pressure chambers B and D are communicated with the constant pressure chambers A and C, and negative pressure is generated between the constant pressure chambers A and C and the variable pressure chambers B and D. It has been introduced and has the same pressure. If the brake pedal is depressed from this state,
The input shaft 34 and the piston 53 integrated with the input shaft 34 are displaced leftward with respect to the valve body 6 and the slide member 21 integrated with the valve body 6. As a result, similar to the conventionally known brake booster, the vacuum valve 35 is closed to cut off the communication between the constant pressure chambers A and C and the variable pressure chambers B and D, and the atmosphere valve 38 is opened to open the variable pressure chambers B and D. Since atmospheric pressure is introduced,
A pressure difference is generated before and after each of the power pistons 14 and 15, and a boosting action is performed.

On the other hand, when the actuator 41 is operated in the non-operating state of the brake booster described above, that is, the flow path of the flow path switching valve 61 is switched and a negative pressure is introduced into the pressure chamber 59. Then, a pressure difference is generated before and after the piston 53, and at the same time, a pressure difference is also generated before and after the stepped tubular member 56 and the seal member 58. The stepped tubular member 5 fixed integrally with the slide member 21.
6 is slidably provided with respect to the valve body 6, so that the slide member 21 is connected to the return spring 4 described above.
Against 4, the valve body 6 and the input shaft 34 are retracted rearward. As a result, similarly to the case where the input shaft 34 is advanced with respect to the slide member 21, the first valve seat 22 formed on the slide member 21 is seated on the valve body 26 to close the vacuum valve 35, and the constant pressure chamber A , C and the variable pressure chambers B and D are cut off, and the valve body 26 is separated from the second valve seat 24 to open the atmosphere valve 38, so that the atmosphere is introduced into the variable pressure chambers B and D. As a result, the constant pressure chambers A and C and the variable pressure chamber B,
Since a pressure difference is generated between the valve body 6 and D, the valve body 6 is advanced and a boosting action is performed. Since the boosting action is performed while the actuator 41 is operating, the pressures in the variable pressure chambers B and D eventually become equal to the atmospheric pressure, and the booster enters the full load state. On the other hand, if the flow path of the flow path switching valve 61 is switched and the atmosphere is introduced into the pressure chamber 59 and the actuator 41 is deactivated, the flow path of the valve mechanism 20 is deactivated as well. The force device returns to its original inoperative state. As described above, according to this embodiment, the function as an automatic brake can be obtained without depressing the brake pedal, and negative pressure acts like a conventional booster having a bellows in the constant pressure chamber. Since the effective area does not decrease, a sufficiently large output can be obtained even with a small booster.

[0014]

As described above, according to the present invention, the effective area on which negative pressure acts is not reduced unlike the conventional device having the bellows in the constant pressure chamber, so that even a small booster can be used. The effect that a sufficiently large output can be secured is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

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

[Explanation of symbols]

6 ... Valve body 20 ... Valve mechanism
21 ... Sliding member 22 ... First valve seat 23 ... Valve plunger
24 ... Second valve seat 25 ... Biasing spring 26 ... Valve body
34 ... Input shaft 35 ... Vacuum valve 38 ... Atmosphere valve
41 ... Actuator 44 ... Return spring 61 ... Actuator

Claims (2)

[Claims] 1. A valve body, which is slidably provided in the shell and has an end portion projecting outward of the shell, and a constant pressure chamber and a variable pressure chamber, which are provided on the outer periphery of the valve body, in the front and rear of the operating direction. A partitioning power piston, a valve mechanism provided in the valve body for controlling communication between the constant pressure chamber, the variable pressure chamber and the atmosphere, and an input for operating the valve mechanism in conjunction with a valve plunger forming the valve mechanism. In a booster having a shaft, a tubular slide member provided with the valve mechanism slidably in the valve body while keeping airtightness, a first valve seat provided on the slide member, and Second on the valve plunger
A valve seat and a cylinder, one end of which is attached to the inner peripheral surface of the slide member, and the other end of which is urged toward the first valve seat and the second valve seat by an urging spring and which is seated on each. -Shaped valve body, a return spring for biasing the input shaft and the slide member in opposite directions to hold the valve mechanism in an inoperative state, and a return spring provided between the input shaft and the slide member. A valve mechanism for a booster, comprising an actuator that operates a valve mechanism by moving a slide member against a spring. 2. The actuator has an inner peripheral portion attached to the input shaft, and an outer peripheral portion keeping airtightness, and a piston slidably provided on a slide member and a seal between the input shaft and the slide member. A seal member that defines a pressure chamber between the seal portion and the piston, and a flow path switching valve that selectively supplies either the atmospheric pressure or the negative pressure to the pressure chamber. The valve mechanism of the booster according to claim 1.