JPS6238437Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a negative pressure booster that boosts the master cylinder of an automobile's hydraulic brake, clutch, etc. using negative pressure.In particular, the booster piston is housed inside the booster shell so that it can freely reciprocate back and forth. The inner peripheral bead of the piston diaphragm is fixed to the boss part of the booster piston, the outer peripheral bead is fixed to the booster shell, and the intermediate pressure receiving part is superimposed on the rear surface of the booster piston, so that the inside of the booster shell is connected to the negative pressure source. The present invention relates to an improvement in a booster which is divided into a working chamber and a first working chamber or a second working chamber whose communication with the atmosphere is switched and controlled via a control valve.

In the above negative pressure booster, when the negative pressure source is not activated, and therefore no negative pressure is stored in the first working chamber, when the booster piston is manually operated to operate the master cylinder, the first
The air in the working chamber is compressed by the advancing booster piston, and the resistance to discharge of the air to the negative pressure source impedes the forward movement of the booster piston, so that manual operation may lack smoothness.

In view of the above, the present invention forms a wave-shaped part that can extend in the radial direction at the overlapped part of the pressure receiving part of the piston diaphragm with the booster piston, whereby the air in the first working chamber is compressed when the booster piston is manually operated. It is an object of the present invention to provide the negative pressure type booster which expands the volume of the first working chamber to absorb the increase in air pressure when the manual operation is performed.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. In Fig. 1, S indicates a negative pressure booster, which is attached to the front of the vehicle body wall (not shown) that constitutes the rear wall of the engine room of the automobile. A brake master cylinder M is attached to the front of this booster S.

A booster piston 2 is housed inside a booster shell 1 of the booster S so as to be able to reciprocate back and forth. The inner circumferential bead 3a of the piston diaphragm 3 is fitted into the annular groove 4 of the boss portion 2a protruding from the center of the rear surface of the booster piston 2, and the outer circumferential bead 3b is fitted into the annular groove 4 of the boss portion 2a protruding from the center of the rear surface of the booster piston 2. It is fitted into the annular groove 5 defined in the overlapping part of the bowl-shaped body 1b, and the intermediate pressure receiving part 3c is overlaid on the rear surface of the booster piston 2, so that the inside of the booster shell 1 becomes a first working chamber in the front part. A and rear second working chamber B
It is divided into The first working chamber A is always in communication with a negative pressure source (not shown), such as an intake manifold, through a negative pressure introduction pipe 6, and the second working chamber B is connected to a negative pressure source (not shown) through a control valve (not shown) operated by an input rod 7. Communication with one working chamber A or the atmosphere can be alternately switched, and the input rod 7 is operated by a brake pedal P.

The pressure receiving portion 3c of the piston diaphragm 3,
A reinforcing bead 3d with a semicircular cross section is protruded on the rear surface of the overlapped portion with the booster piston 2, which improves the rigidity of the pressure receiving portion 3c and abuts against the rear surface of the booster shell 1 to restrict the retraction limit of the booster piston 2. An annular corrugated portion 3e concentric with the reinforcing bead 3d is formed in the pressure receiving portion 3c between the bead 3d and the inner peripheral bead 3a. In the figure, 8 is an output rod protruding from the booster piston 2, and 9 is a return spring for the booster piston 2.

In the above configuration, if the second working chamber B is communicated with the atmosphere, the pressure difference generated between the two working chambers A and B will give thrust to the booster piston 2, and its forward movement will actuate the master cylinder M via the output rod 8. do. In this case, since the reinforcing bead 3d restrains the corrugated portion 3e from expanding in the radial direction, the booster piston 2 can move forward appropriately in response to the pressure difference.

On the other hand, if the booster piston 2 is manually actuated to operate the master cylinder M when the negative pressure source is not activated, and therefore no negative pressure is stored in the first working chamber A, the pressure inside the first working chamber A is Air is compressed by the advancing booster piston 2,
At this time, as shown in FIG. 2, the piston diaphragm 3 expands and deforms rearward while extending the corrugated portion 3e in the radial direction between the reinforcing bead 3d and the inner peripheral bead 3a, so that the volume of the first working chamber A increases. is expanded, thereby absorbing the increase in air pressure and making manual operation of the booster piston 2 easier.

As described above, according to the present invention, the waveform portion 3e that can extend in the radial direction is formed at the overlapped portion of the pressure receiving portion 3c of the piston diaphragm 3 with the booster piston 2, so that the air in the first working chamber A is When compressed, by expanding the waveform portion 3e, the first
The volume of the working chamber A can be expanded to absorb the increase in air pressure, which allows the booster piston 2
can be easily operated manually. Moreover, since an annular reinforcing bead 3d surrounding the corrugated portion 3e is formed in the pressure receiving portion 3c, during boosting operation, the reinforcing bead 3d restrains the expansion of the corrugated portion 3e, and the booster piston is removed from the piston diaphragm 3. It is possible to reliably transmit the operating force to 2.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with FIG. 1 being a longitudinal side view and FIG. 2 being a longitudinal side view of the main parts. A, B...First and second working chambers, S...Negative pressure booster, 1...Booster shell, 2...Booster piston, 2a...Boss portion, 3...Piston diaphragm, 3a, 3b... ...Inner, outer bead, 3c
...Pressure receiving part, 3d...Reinforcement bead, 3e...Corrugated part.

Claims (1)

[Scope of utility model registration request] Booster piston 2 inside booster shell 1
is housed so as to be able to reciprocate back and forth, and the inner peripheral bead 3a of the piston diaphragm 3 is connected to the booster piston 2.
An outer peripheral bead 3b is fixed to the boss portion 2a of the booster shell 1, and an intermediate pressure receiving portion 3c is superimposed on the rear surface of the booster piston 2, thereby forming a first working chamber in which the inside of the booster shell 1 is connected to a negative pressure source. In the negative pressure booster, the booster of the pressure receiving portion 3c of the piston diaphragm 3 is divided into a first working chamber A and a second working chamber B whose communication with the atmosphere is switched and controlled via a control valve. A negative pressure booster in which a corrugated portion 3e that can extend in the radial direction is formed at the overlapped portion with the piston 2, and an annular reinforcing bead 3d that surrounds the corrugated portion 3e.