JPH0986392A - Pneumatic pressure type booster device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the length in the axial direction without sacrificing the rigidity of a shell main body and the stroke of a power piston. SOLUTION: The front wall 31 of a front shell 2 to compose a shell main body 1 is made in the form consisting of a plane part 32 around an output shaft 21 which is extended from a valve body 13 supported to a power piston 7; an incline 33 inclined from the plane part 32 to the rear side; and a swelling 34 swelled from the incline 33 to the front side and connected to an outer peripheral wall 35. While the outer peripheral edge 7a of the power piston 7 which advances in a booster operation is escaped to the rear side of the swelling 34 so as to guarantee the stroke of the valve body 13, the regidity of the shell main body 1 is guaranteed by the inclination α of an incline 34. Consequently, even though the front shell 2 is retreated to the rear side as a distance S, no inconvenience in the functional and the strength respects is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic booster used for a vehicle brake system.

[0002]

2. Description of the Related Art For example, a tandem type pneumatic booster is
Conventionally, it generally has a structure as shown in FIG. In the figure, reference numeral 1 denotes a shell body composed of a front shell 2 and a rear shell 3, and the inside of the shell body 1 is divided into front and rear two chambers by a center shell 4, and the front and rear two chambers further include a diaphragm 5 and a diaphragm 5, respectively. Power pistons 7, 8 with 6
Constant pressure chambers (negative pressure chambers) 9 and 10 and operating pressure chambers 11 and 12
It is divided into and. A hollow valve body 1 in which the center shell 4 and the rear shell 3 are slidably inserted into the respective power pistons 7 and 8 and extended to the rear of the rear shell 3
3 is supported, and this valve body 13 has a front
The negative pressure passage 14 that communicates the rear negative pressure chambers 9 and 10, the air passage 15 that communicates the front and rear working pressure chambers 11 and 12, and the negative pressure passage 14 and the air passage 15 respectively communicate with the hollow interior. Communication passages 16 and 17 are provided.

An input shaft 1 is provided inside the hollow of the valve body 13.
A valve mechanism 19 interlocking with the valve body 8 is provided, and a base end portion of an output shaft 21 extending through the center of a front wall 20 of the front shell 2 slidably extends to the front end of the valve body 13 as a reaction disc. It is operatively connected via 22. The valve mechanism 19 includes a plunger 23 that is operatively connected to the input shaft 18, and a valve body 26 that can be seated on and detached from valve seats 24 and 25 formed at the rear end of the plunger 23 and the open end of the communication passage 16. I have it. On the other hand, the front wall 20 of the front shell 2 is provided with an inlet 27 for introducing, for example, engine negative pressure, and the negative pressure introduced from the inlet 27 into the front negative pressure chamber 9 is negative. It is also supplied to the negative pressure chamber 10 on the rear side through the passage 14. A cup portion 28 for receiving a master cylinder (not shown) is formed in the center of the front wall 20 of the front shell 2.
A return spring 29 is provided between the bottom of the cup portion 28 and the front end of the valve body 13 to return the power pistons 7 and 8 to their original positions (the positions shown in the drawing) after a boosting action to be described later. Are

In such a pneumatic booster, when a brake pedal (not shown) is depressed, the input shaft 18 moves forward and the plunger 23 moves leftward in the figure, and the valve seat at the rear end of the plunger 23. 24 separates from the valve body 26 and the working pressure chamber 1
Atmosphere is introduced into the insides of 2 and 11. As a result, a differential pressure is generated between the negative pressure chambers 9 and 10 into which the negative pressure is introduced and the working pressure chambers 11 and 12, and the front and rear power pistons 7 and 8 are largely propelled (advanced), The propulsive force is transmitted to the master cylinder via the output shaft 21, and a so-called boosting action is performed. The reaction force at the time of this boosting action is transmitted from the reaction disc 22 to the input shaft 18 via the plunger 23.

In the pneumatic booster described above, the front shell 2 and the rear shell 3 which form the shell body 1
Is thin in order to reduce the weight, but if it is simply thinned, the rigidity is lowered and the shell body 1 is deformed. Therefore, conventionally, as shown in FIG. 3 as well, the front wall 20 of the front shell 2 is inclined at a predetermined angle rearward from the central disc portion 20a orthogonal to the output shaft 21 and the disc portion 20a. And an umbrella-shaped inclined portion 20b that is widened toward the outer peripheral wall.
A desired rigidity is secured by 0b. Note that the reinforcing plate 30 may be joined to the back surface of the disc portion 20a of the front shell 2 in order to further increase the rigidity.

[0006]

By the way, recently, in addition to the above-described weight reduction, there is an increasing demand for reducing the axial dimension of the shell body 1 to reduce the overall size. However, in order to reduce the axial dimension, if the central disc portion 20a is simply driven (retracted) to the rear side and the inclination angle of the inclined portion 20b is reduced, the rigidity of the shell body 1 decreases, while the inclination of the inclined portion 20b decreases. When the central disc portion 20a is driven toward the rear side while keeping the angle as it is, the connecting portion between the inclined portion 20b and the outer peripheral wall of the front shell 2 also shifts toward the rear side, and the outside of the power piston 7 that has moved forward during the boosting action. There is a problem in that the peripheral portion (shown by the one-dot chain line in FIG. 3) interferes with the connecting portion, and it is impossible to achieve the desired miniaturization.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to achieve overall miniaturization without sacrificing the rigidity of the shell body and the stroke of the power piston. It is in.

[0008]

In order to achieve the above object, the present invention divides the inside of a shell body consisting of a front shell and a rear shell into a constant pressure chamber and a working pressure chamber by a power piston having a diaphragm. The power piston is supported by a valve body having a built-in valve mechanism interlocking with the input shaft, and a differential pressure is generated between the constant pressure chamber and the working pressure chamber by the operation of the valve mechanism to propel the power piston, and its propulsive force is In a pneumatic booster adapted to be taken out through an output shaft extended through the center of the front wall of the front shell, the front wall of the front shell is provided with a central disc portion orthogonal to the output shaft. , An umbrella-shaped sloping portion which is inclined rearward from the disc portion at a predetermined angle and is expanded toward the outer peripheral wall, and a ring-shaped swelling portion which is bulged forward from the inclined portion and connected to the outer peripheral wall. Characterized in that the composed shape.

In the pneumatic booster configured as described above, even if the front wall of the front shell is driven to the rear side without reducing the inclination angle of the inclined portion, the inside of the ring-shaped bulging portion acts as a booster. It sometimes functions as an escape for the advancing power piston, and the stroke of the power piston is guaranteed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show a pneumatic booster of the present invention. The pneumatic booster is constructed as a tandem type, and its overall structure is shown in FIG. Since they are the same as those shown, the same parts are designated by the same reference numerals, and the description thereof will be omitted. In the present embodiment, the front wall 31 of the front shell 2 is the output shaft 2
1, a central disc portion 32, an umbrella-shaped slant portion 33 that is slanted rearward from the disc portion 32 at a predetermined angle toward the outer peripheral wall 35 of the front shell 2, and the slant portion. 33, and a ring-shaped bulge portion 34 that bulges forward from 33 and is connected to the outer peripheral wall 35. Disk part 32
Is provided with a cup portion 28 for receiving the master cylinder as in the conventional case, the cup portion 28 is formed integrally with the front shell 2 when the front shell 2 is molded.
8a and a seal plate 28 attached to the bottom of the cylindrical body 28a
b, and the output shaft 21 is extended by hermetically inserting the seal plate 28b. Further, the reinforcing plate 30 is joined to the back surface of the disc portion 32 as in the conventional case,
The reinforcing plate 30 is a stud bolt 36 for mounting the master cylinder, which is fixed to the front wall 31 of the front shell 2 by caulking.
Is integrated with the front shell 2.

As shown in FIG. 2, the disc portion 32 of the front wall 31 of the front shell 2 is driven toward the rear side by a predetermined distance S from the disc portion 20a of the conventional front wall 20. ing. Further, the inclined portion 33 of the front wall 31 extends from the disc portion 32 toward the outer peripheral wall 35 of the front shell 2 at the same inclination angle α as the disc portion 20a of the conventional front wall 20. On the other hand, the bulging portion 34 of the front wall 31 of the front shell 2 is set to have a bulging amount so as not to interfere with the outer peripheral edge portion 7a of the power piston 7 advanced when the boosting force is applied.

The operation of the booster of the present embodiment is similar to that of the conventional one shown in FIG. 3, and when the brake pedal (not shown) is depressed, the input shaft 18 moves forward and the valve mechanism 19 is operated. And the atmosphere is introduced into the two working pressure chambers 12 and 11, and a differential pressure is generated between the working pressure chambers 12 and 11 and the negative pressure chambers 9 and 10 in which the negative pressure is introduced. However, as shown in FIG. At this time, power piston 7
The outer peripheral edge portion 7a enters the inside of the bulging portion 34 of the front wall 31 of the front shell 2, and the stroke of the power piston 7 is sufficiently ensured, so that the boosting action is not sacrificed.

The disc portion 32 of the front wall 31 of the front shell 2 in this embodiment is the disc portion 20 of the conventional front wall 20.
Since it is driven toward the rear side by a predetermined distance S from a, the axial length of this booster is the same as that of the conventional booster (Fig. 3).
It is shorter than the above by the distance S described above. Moreover, the inclination angle α of the inclined portion 33 of the front wall 31 is equal to that of the conventional front wall 2.
Since it is the same as the inclined portion 20b of 0, the rigidity of the front shell 2 does not decrease. By the way, the disk part 3
When only 2 is driven to the rear side by the distance S and the inclination angle of the inclined portion is reduced as shown by the broken line A, the rigidity of the front shell 2 is reduced, while the bulging portion 34 is not provided and the inclined portion is not provided. Is directly connected to the outer peripheral wall 35, the broken line B
As indicated by, the connecting portion between the inclined portion 33 and the outer peripheral wall 35 retreats toward the rear side, and the outer peripheral edge portion 7a of the power piston 7 interferes with this connecting portion during the boosting action. The present invention is not limited to the tandem type, and it goes without saying that it may be configured as a single type having a pair of a constant pressure chamber and a working pressure chamber.

[0015]

As described above, according to the pneumatic booster of the present invention, the overall axial length can be shortened without sacrificing the rigidity of the shell body and the stroke of the power piston. There is great utility value.

[Brief description of drawings]

FIG. 1 is a sectional view showing an overall structure of a pneumatic booster of the present invention.

FIG. 2 is a cross-sectional view showing a main structure of a pneumatic booster of the present invention.

FIG. 3 is a sectional view showing the overall structure of a conventional pneumatic booster.

[Explanation of symbols]

 1 Shell Main Body 2 Front Shell 3 Rear Shell 4 Center Shell 5,6 Diaphragm 7,8 Power Piston 9,10 Constant Pressure Chamber (Negative Pressure Chamber) 11,12 Working Pressure Chamber 13 Valve Body 18 Input Shaft 19 Valve Mechanism 21 Output Shaft 31 Front Wall 32 Disc part 33 Sloping part 34 Bulging part 35 Peripheral wall

Claims (1)

[Claims] 1. A valve body having a shell body composed of a front shell and a rear shell partitioned into a constant pressure chamber and a working pressure chamber by a power piston having a diaphragm, and the power piston having a built-in valve mechanism interlocking with an input shaft. And an output shaft extending the thrust force through the front wall of the front shell by propelling the power piston by generating a differential pressure between the constant pressure chamber and the working pressure chamber by the operation of the valve mechanism. In the pneumatic booster configured to be taken out through, the front wall of the front shell is provided with a central disc portion orthogonal to the output shaft and tilted backward from the disc portion at a predetermined angle. A pneumatic booster having a shape including an umbrella-shaped sloping portion that expands toward the outer peripheral wall and a ring-shaped swelling portion that bulges forward from the sloping portion and is connected to the outer peripheral wall.