JP3141473B2 - Negative pressure booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative pressure type booster used as a component of a brake device for a vehicle, for example, in which a reaction force at the time of operation is transmitted to a brake pedal via a reaction disk. It was done.

[0002]

2. Description of the Related Art An example of this kind of prior art is disclosed in Japanese Utility Model Laid-Open Publication No. 1-123578. On the other hand, a plunger is slidably fitted into a small diameter hole in the valve body, one end of an input shaft linked to a brake pedal is connected, and a force that sequentially increases the operating force applied to the input shaft during operation is applied to the plunger. Communicated,
Before the force acting on the output rod is applied, the plunger pushes the reaction disk and is transmitted to the output shaft via the reaction disk to start the boosting operation.

[0003]

In the above-described conventional vacuum booster, the output load after reaching the limit of the negative pressure range (hereinafter referred to as servo range) is indicated by the dotted line in FIG. Is increased by the driver's operation force applied to the brake pedal, so that the servo ratio suddenly changes and the user feels as if the brake pedal is on the floor (so-called bottoming).

Accordingly, it is an object of the present invention to provide a negative pressure booster of this type in which the driver's discomfort is eliminated and the feeling to the driver is improved.

[0005]

Configuration of the Invention

[0006]

According to the technical means of the present invention taken to solve the above-mentioned technical problem of the present invention, a hub member in a housing and an outer peripheral portion thereof are hermetically fixed to the housing. At the same time, the inner periphery is partitioned into at least one set of a constant pressure chamber and a variable pressure chamber by a power piston including at least one diaphragm hermetically fixed to the hub member, and is incorporated in the power piston and interlocked with the input rod. The differential pressure between the variable pressure chamber and the constant pressure chamber is controlled by the operation of the valve mechanism, and the operating force applied to the air valve connected to the input rod is transmitted and assisted by the power piston. In a negative pressure booster equipped with a reaction disk that transmits force to the output rod, the reaction disk and the power piston Rutotomoni disposed between the air valve
A hollow cylindrical member through which
And a resilient member having elasticity that is at least harder than the reaction disk and disposed between the stone and the stone.
Preferably, the elastic body has a thin center portion, or the hollow cylindrical member has an outer diameter of the reaction disc.
The outside diameter of the reaction
The output rod is formed integrally with the output rod through a screw , and furthermore, the length between the hollow cylindrical member and the power piston and the length between the reaction disk and the air valve are made to be substantially the same length. It is characterized by having been done.

[0007]

According to the above-described technical means of the present invention, the elastic body is elastically deformed by the input load from the input rod due to the pushing by the operation of the valve mechanism during the operation, and the constant pressure chamber side is caused by the elastic deformation. As the input load increases, the output load can be reduced by the elastic body to reduce the pressure when the input load increases.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the technical means of the present invention will be described below in more detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a tandem type vacuum booster for a brake. A housing 1 of the vacuum booster has a front shell 2 having a cup-like shape.
A rear shell 3 in the form of a plate, which is hermetically assembled to the rear end of the front shell 2 and attached to the rear of a vehicle dashboard (not shown), and an intermediate shell 4.
The interior is formed by an intermediate shell 4 in front chamber Ra and rear chamber Rb.
Is divided into A front power piston 5 and a rear power piston 8 are arranged in the front constant pressure chamber Ra and the rear constant pressure chamber Rb.

The front power piston 5 is connected to the hub member 3.
0, a front power plate 6, and a diaphragm 7, and the hub member 30 is made of resin. The inside of the front chamber Ra is partitioned into a front variable pressure chamber ra1 and a front constant pressure chamber ra2, and the front power plate 6 and the diaphragm 7 It is kept airtight.

The front power plate 6 has its inner peripheral portion locked to the hub member 30, and the diaphragm 7 is provided on the rear surface of the front power plate 6, and is hermetically sandwiched between the outer periphery of the hub member 30. I have.

On the other hand, the rear power piston 8 comprises a hub member 30, a rear power plate 9, and a diaphragm 10, and the hub member 30 moves inside the rear chamber Rb into the rear variable pressure chamber r.
b1 and a rear constant pressure chamber rb2, which are hermetically held by the rear power plate 9 and the diaphragm 10.

The rear power plate 9 has its inner peripheral portion locked with the hub 30, and the diaphragm 10 is provided on the rear surface of the rear power plate 9, and is airtightly held around the outer periphery of the hub member 30. .

The valve mechanism 20 is operated by a well-known operation, and selectively connects the rear variable pressure chamber ra1 to the rear constant pressure chamber ra2 or the atmosphere. The valve mechanism 20 includes an air valve 21, a control valve 22, and the like. standing.

The air valve 21 is slidable in the axial direction on the reaction disc case 24 in the hub member 30 in a state where the air valve 21 is attached to the front end of an input rod 23 interlocking with a brake pedal (not shown) at the rear end 21a. It is inserted in. A hollow cylindrical member 25 having a hollow cylindrical shape is slidably fitted on the outer peripheral surface of the distal end portion 21b.

The hollow cylindrical member 25 is connected to the air valve 2.
1 is provided so as to be able to penetrate in the axial direction, and the space between the air valve 21 and the reaction disk 26 is usually set to be ρ. A concave portion 25a is formed in the outer peripheral portion via an air valve 21, and an elastic body 28 having elasticity is attached to the concave portion 25a. Also, the reaction disk 26 side of the output rod is
6 and have the same area ratio by contacting them with substantially the same diameter. Further , the hollow cylindrical member 25 is a reaction disc.
26 and the reaction
Disk 26, with the output rod that is integrally molded. That
Therefore, the hollow cylindrical member 25 is capable of defining the amount of movement to the air valve side integrally with the output rod 27.

The output rod 27 has one end extending airtightly through the front shell 2 to the housing 1 and connected to a master cylinder (not shown). The output rod 27 is inserted into the reaction disk case 24. The reaction disk case 24 is fixed in the inner peripheral surface 30a of the hub member 30, and always receives the reaction disk 26 by being biased rightward in FIG. The reaction disk 26 is made of rubber and is interposed between the hollow cylindrical member 25 and the output rod 27.

The elastic body 28 is usually made of rubber, and has a drum-shaped cross section as shown in FIG. 1 and FIG. The elastic body 28 is formed in a hollow cylindrical shape along the shape 25 and has excellent durability and strength. Further, as in a state where the length of the elastic body 28 protrudes from the hollow cylindrical member 25, the length is formed to be longer than the δ length and is substantially the same as the distance between ρ between the air valve 21 and the reaction disk 26, When the input load is further increased from the initial state at the time of operation and the reaction disk case 24 is pushed forward, the assisting force for pushing the reaction disk case 24 to the elastic body 28 by the servo area is generated by the elastic deformation by the elastic body 28. When the δ length is reduced, the hollow cylindrical member 25 is pressed by the pressing of the reaction disk case 24, and the distance between ρ between the air valve 21 and the reaction disk 26 is reduced, and the output load is reduced accordingly. By transmitting to the output rod 27 via the reaction disk 26, the brake is applied with low load (low servo range). It has become way. The servo ratio applied to the output load can be freely changed by the input load.

Although a drum shape is used here, a drum shape or a spherical shape (not shown) can be attached. Furthermore, although the elastic body is made of rubber, it can be attached even if an elastic hard spring is used instead of rubber.

The operation of this embodiment having the above-described configuration will be described.

When a forward operation force is applied to the input rod 23 by depressing a brake pedal (not shown), the pressure rise in the rear transformer chamber rb1 and the front transformer chamber ra1 caused by the well-known operation of the valve mechanism 20. The front power piston 5 and the rear power piston 8
Is pushed forward and is sequentially applied to a pressure chamber (not shown), whereby the inner peripheral portion 30a of the hub member 30 is
Are sequentially pushed toward the front constant pressure chamber ra2 with respect to the reaction disk case 24 and transmitted to the output rod 27.

Therefore, in the initial stage of the above operation, as shown in FIG. 2, the output load transmitted to the output rod 27 increases sequentially in proportion to the increase of the input rod applied to the input rod 23.

Further, with the brake pedal further depressed, the input load increases and the atmosphere is introduced into the front and rear transformation chambers ra1 and rb1, while the pressure in the pressure chamber (not shown) rises. In response to the pressure increase, the inner peripheral portion 30a of the hub member 30 is
4, the input rod 23 and the air valve 21 move forward, the valve mechanism 20 is also operated, and the front power piston 5 and the rear power piston 8 are sequentially operated. As a result, the elastic body 28 is elastically deformed by the pushing of the reaction disk case 24 and contracts by the protruding δ length, and is pushed forward by the hollow cylindrical member 25 so that there is no space between ρ between the air valve 21 and the reaction disk 26. , The air valve 21 and the reaction disk case 24 push the hollow cylindrical member 25 forward, and are transmitted to the output rod 27. In addition, as shown in FIG. 2, the elastic displacement of the protruding δ length is changed by the input load, and the increase of the output load is reduced, so that the servo ratio becomes smaller than before and a smooth curve can be drawn. .

When the brake is released, the operation is substantially the same as the conventional operation, and the description thereof is omitted.

In the above embodiment, the present invention is applied to a tandem type vacuum booster. However, the present invention can be similarly applied to a single type or triple type vacuum booster. is there.

[0026]

As described above, according to the present invention, the length between the hollow cylindrical member and the power piston and the length between the reaction disk and the input rod are made substantially the same,
In addition, by making the diameter of the reaction disk and the hollow cylindrical member substantially the same, the impact from the input rod to the reaction disk is maintained, the durability of the reaction disk is improved, and the width of the elastic body is increased by making the center portion of the elastic body thin. By using an elastic body having good elasticity and having an elasticity harder than that of the reaction disk, the driver does not have discomfort (so-called bottoming) and improves feeling. Can achieve the intended purpose.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a negative pressure booster to which the present invention is applied.

FIG. 2 is a graph showing a performance comparison between the present invention and a conventional one.

FIG. 3 is an enlarged sectional view of a portion A to which the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Housing 2 Front shell 3 Rear shell 4 Intermediate shell 20 Valve mechanism 21 Air valve, 21a Rear end, 21b Tip 23 Input rod 24 Reaction disk case 25 Hollow cylindrical member 26 Reaction disk 27 Output rod 28 Elastic body 30 Hub member, 30a Inner circumference Ra front chamber, ra1 front transformer chamber, ra2 front constant pressure chamber Rb rear chamber, rb1 rear transformer chamber, rb2 rear constant pressure chamber

Claims (4)

(57) [Claims] 1. A power piston comprising a hub member inside a housing and at least one diaphragm whose outer periphery is hermetically fixed to the housing and whose inner periphery is hermetically fixed to the hub member. A differential pressure between the variable pressure chamber and the constant pressure chamber is controlled by an operation of a valve mechanism which is divided into a set of a negative pressure constant pressure chamber and a variable pressure chamber, and is incorporated in the power piston and linked to an input rod, thereby controlling the input pressure. A negative pressure type booster equipped with an output rod in which an operating force applied to an air valve connected to the rod is transmitted by being assisted by the power piston, and a reaction disk built in the hub member and transmitting a force to the output rod. in, Rutotomoni the air valve through is disposed between the reaction disc and the power piston Noh hollow
A cylindrical member, the hollow cylindrical member and the power piston
And a resilient member having elasticity hardened at least than the reaction disk. 2. The vacuum booster according to claim 1, wherein the elastic body has a thin center portion. Wherein said hollow cylindrical member, the rear together with the outer diameter is substantially the same as the outer diameter of the reaction disc
The output lock is
The outside diameter of the contact part with the reaction disk is
The outer diameter of the reaction disk is approximately the same as
2. The vacuum booster according to claim 1, wherein the booster is integrally formed with the reaction disk . 4. A length between the hollow cylindrical member and the power piston and a length between the reaction disk and the air valve are substantially equal to each other.
The hollow cylindrical member as described in the above.