JP2559351Y2 - Negative pressure booster - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a booster shell in which a booster piston is accommodated in a reciprocating manner, and a piston boss connected to the booster piston is slidably provided with a reaction piston connected to an input rod. A small-diameter cylinder hole to be fitted and a large-diameter cylinder hole having a larger diameter than the small-diameter cylinder hole and opening on the front surface of the piston boss are provided coaxially.
The present invention relates to a negative pressure booster in which an elastic piston opposed to the reaction force piston and an output piston having an output rod are slidably fitted in the large-diameter cylinder hole with each other.

[0002]

2. Description of the Related Art Conventionally, such a negative pressure booster is known, for example, from Japanese Utility Model Publication No. 58-45971.

[0003]

All the above-mentioned negative pressure booster The present invention is to provide a
The elastic piston uses the piston boss to
And the reaction force piston at a fixed ratio.
Bulging deformation so that part of
Is what you do. That is, when the output rod is operated, its operation reaction force
When a compressive force is applied to the elastic piston by
Functions as a kind of fluid, and acts as a piston boss and reaction force.
Pressure is applied to each pressure receiving surface of the piston.
Depending on the area ratio of the pressure surface, the piston boss and the
The transmission ratio to the reaction piston is determined. And the reaction force
The reaction force transmitted to the stone is fed back to the input rod.
You. Therefore, if the transmission ratio of the operation reaction force is not deviated,
Changes the driver's operation feeling for the input rod
Then, a sense of incongruity occurs.

[0004] By the way, in the above-mentioned conventional one, the elastic pi
The entire ton is made of elastic rubber,
Hardness tends to increase as the temperature decreases.
Therefore, the elastic piston receives the operation reaction force of the output rod.
The resistance of the elastic piston to swell into the small-diameter cylinder hole increases.
If the transmission ratio of the above operation reaction force is out of order,
May affect the operation feeling of the input rod.
You.

Conventionally, in a negative pressure booster, a reaction force
The volume expansion between the stone and the elastic piston due to the temperature drop
An adjuster mechanism that encapsulates a liquid such as oil
It is known to be installed (Japanese Utility Model Laid-Open No. 3-107272).
However, the mechanism includes a reaction piston and an elastic piston.
The gap between the stones is kept constant regardless of the temperature change,
To stabilize the jump-up characteristics of
Depending on the mechanism, elastic fixie regardless of temperature change
Since the deformation characteristics of the
Of the reaction force of the piston to the piston boss and reaction piston
Cannot be stabilized.

The present invention has been made in view of such circumstances, and makes the deformation characteristics of the elastic piston substantially constant regardless of the temperature change, and makes the piston boss of the operation reaction force of the output rod.
It is another object of the present invention to provide a negative pressure booster that stabilizes a transmission ratio to a reaction force piston and prevents a change in operation feeling.

[0007]

According to the present invention, in order to attain the above object, an elastic piston has a fluidity almost completely changed even by temperature change in a closed bag made of elastic rubber.
No fluids are enclosed.

[0008]

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

FIGS. 1 and 2 show an embodiment of the present invention. First, in FIG. 1, a master cylinder M operated by the booster B is provided on a front wall of a booster shell 1 in a negative pressure booster B. Is attached.

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. A booster piston 2 is accommodated in the booster shell 1 so as to be able to reciprocate back and forth. On the rear surface of the booster piston 2, a diaphragm 3 whose outer periphery is sandwiched between abutting portions of the two shell halves 1a and 1b is superimposed. 5
Is combined with Moreover the booster shell 1 by the booster piston 2 and the diaphragm 3 is partitioned with 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 3 You.

At the rear end of the piston boss 5, a valve cylinder 5a is integrally formed so as to protrude therefrom.
A rear extension cylinder 8 is provided at the center of the rear wall to cover the valve cylinder 5a and has an air inlet 7 at the rear end, and is slidably supported via a bush 9 and a seal member 10.

On the front wall of the booster shell 1, a negative pressure introducing pipe 1 is provided.
The negative pressure chamber _RA is always in communication with the intake manifold (not shown) of the internal combustion engine, which is a negative pressure source, through the negative pressure introducing pipe 11.

An input rod 13 is connected to the brake pedal 12, and a valve piston 14 swingably connected to the input rod 13 is slidably fitted to the piston boss 5. Control valve 15 for switching operation Thus to in accordance with the relative movement between the piston boss 5 of the valve piston 14 by advancing and retracting operation of the input rod 13 in response to operation of the brake pedal 12 is, the working chamber R _B, the negative pressure chamber It is interposed between R _A and the air inlet 7.

The control valve 15 is a well-known control valve provided with the valve piston 14 and a rubber valve body 16 sandwiched between the inner walls of the piston boss 5. When the brake pedal 12 is not operated, a negative pressure chamber is provided. R _a and working chamber biventricular while blocking communication between the R _B R _a, are also blocked communication between the air inlet 7 of R _B. Further, when the valve piston 14 by the operation of the brake pedal 12 is advanced relative to the piston boss 5, retracting operation control valve 15 is communicated with the working chamber R _B to the air inlet 7 for further valve piston 14 is a piston boss 5 Then, the control valve 15 to communicate with the working chamber R _B to the negative pressure chamber R _a.

The piston boss 5 is provided with a large-diameter cylinder hole 17 opening at the center of the front surface and a small-diameter cylinder hole 18 coaxially connected to the rear of the cylinder hole 17. , Reaction force piston 1 integral with valve piston 14 or in contact with the front surface of valve piston 14
The elastic piston 20 and the output piston 21 are slidably fitted in the large-diameter cylinder hole 17 by abutting each other. An output rod 22 projects from the front surface of the output piston 21, and is connected to an operating piston 23 of the master cylinder M.

A retainer 24 made of synthetic resin is fitted and abutted on the front surface of the piston boss 5 to prevent the output piston 21 from dropping out of the large-diameter cylinder hole 17. the return spring 25 is mounted under compression between the front wall, the booster piston 2 is always urged backward or working chamber R _B side, the backward limit of the booster piston 2 is raised to the surface after the diaphragm 3 formed The projected protrusion 3a is regulated by contacting the inner surface of the rear wall of the booster shell 1.

Referring also to FIG. 2, the elastic piston 20
Is formed by enclosing a chemically synthesized oil such as silicone grease as a fluid 20b, whose fluidity hardly changes even with a temperature change, in a closed bag 20a made of elastic rubber. Has a disk shape.

[0018] Next, to explain the action of this embodiment, the air inlet 7 of the control valve 15 is operating chamber R _B in accordance with the advancing operation of the input rod 13 in response to depression of the brake pedal 12
Allowed communicating with, thereby the atmospheric pressure acts on the working chamber R _B, booster piston 2 moves forward actuated by a large pressure difference occurs between the negative pressure chamber R _A and working chamber R _B, the output rod 22
, The operating piston 23 of the master cylinder M can be boosted. The input rod 13, retracting actuation upon release of the operating force has to act on it, operating chamber R _B by the control valve 15 is communicated with the negative pressure chamber R _A together are cut off the communication with the atmosphere introduction port 7 Therefore, the working chamber R
The pressure difference between _B and the negative pressure chamber _RA decreases, and the return spring 25
With this force, the booster piston 2 moves backward.

By the way, in the depression initial brake pedal 12, the booster piston 2 moves forward by the control valve 15 when the valve piston 14 moves forward by a predetermined stroke communicates the actuation chamber R _B to the air inlet 7 Then, the braking pressure is output from the master cylinder M, and the play to the brake terminal is removed in accordance with the increase in the braking pressure. When the output of the output rod 22 increases, the operation reaction force acts on the elastic piston 20 via the output piston 21, and the elastic piston 20 functions as a kind of fluid.
It swells toward the small-diameter cylinder hole 18 side,
Whether to apply pressure to each pressure receiving surface of the force piston 19
The transmission ratio determined by the area ratio of those pressure receiving surfaces
Accordingly, the above-mentioned reaction force is applied to the booster piston 2 and the reaction force pin.
The input transmitted to the stone 19 and transmitted to the reaction force piston 19
Feedback to the brake pedal 12 via the power rod 13
Is done.

In such a negative pressure booster B, the elastic piston 20 is formed by enclosing a fluid 20b made of a synthetic oil such as silicone grease in a sealed bag 20a made of elastic rubber. Piston 20
Of the elastic piston 20 does not change according to the temperature, so that the booster piston of the operation reaction force of the output rod 22 does not change according to the temperature.
2 and stabilization of the transmission ratio to the reaction force piston 19
Therefore, the operation fee of the brake pedal 12 is
The ring does not change according to the temperature change, and a substantially constant operation feeling can be obtained.

[0021] The present invention is not only vacuum booster B on both sides of a single diaphragm 3 is the negative pressure chamber R _A and working chamber R _B are formed as in the above embodiment, the negative pressure chamber and the working chamber The present invention is also applicable to a tandem type negative pressure booster provided with a pair.

[0022]

As described above, according to the present invention, the elastic piston is provided in a sealed bag made of elastic rubber to change the temperature.
In addition, since a fluid that hardly changes in fluidity is sealed, a change in the hardness of the elastic piston due to a change in temperature is suppressed, and the piston boss and the reaction force piston of the output rod operating reaction force are suppressed.
Stabilize the transmission ratio to
It may be maintained substantially constant.

[Brief description of the drawings]

FIG. 1 is a vertical side view of a negative pressure booster according to an embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Booster shell 2 Booster piston 5 Piston boss 13 Input rod 17 Large-diameter cylinder hole 18 Small-diameter cylinder hole 19 Reaction force piston 20 Elastic piston 20a Closed bag 20b Fluid 21 Output piston 22 Output rod B Negative pressure booster

Claims (1)

(57) [Scope of request for utility model registration] A booster piston (2) is accommodated in a booster shell (1) so as to be able to reciprocate back and forth, and a piston boss (5) connected to the booster piston (2) has an input rod (13). A small-diameter cylinder hole (18) into which a continuous reaction force piston (19) is slidably fitted, and a large-diameter cylinder having a diameter larger than the small-diameter cylinder hole (18) and opening at the front surface of the piston boss (5). The large-diameter cylinder hole (17) has an elastic piston (20) facing the reaction force piston (19) and an output piston (21) having an output rod (22). The elastic piston (20) has a fluidity almost changed by a temperature change in a closed bag-like body (20a) made of elastic rubber. I
Negative pressure booster characterized by being filled with no fluid (20b).