JPS591873Y2 - Silencer for vacuum booster - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a silencing device for a vacuum booster, and its purpose is to reduce air intake noise generated when the vacuum booster operates.

Vacuum boosters have traditionally been widely used to reduce the force required to operate brakes or clutches in vehicles by utilizing the vacuum-atmospheric pressure difference, but in recent years, with the increase in output and quieter vehicle driver seats, As a result, the dry suction noise generated when the vacuum booster is activated has become a problem.

The present invention aims to reduce vacuum suction noise by making the air circulation path inside the filter long and curved, and also ensures that a sufficient amount of air is supplied even in such a circulation path. To provide a muffling device that does not impair the responsiveness of a booster.

The invention will now be described with reference to the illustrated embodiments.

The basic configuration of the vacuum booster 1 is the same as the conventionally known one, and inside the outer shell consisting of a front shell 2 and a rear shell 3, a diaphragm 4, a power piston 5, and a sealing material 6 form two chambers at 7°B. are separated.

When the vacuum booster 1 is not in operation, the negative pressure introduced into one chamber 7 through the inlet 9 flows through the passage 10° formed in the power piston 5, the valve body 12 constituting the valve mechanism 11, and the first The power piston 5 is introduced into the other chamber B through the gap between the valve seat 13 and the passage 14, and in this state, the power piston 5 is held at the illustrated position by the return spring 15.

When the brake pedal (not shown) is depressed and the input shaft 16 connected to the brake pedal is moved to the left, the valve body 12 seats on the first valve seat 13 and blocks communication between the chambers 7 and 8. Since the second valve seat 17 is separated from the valve body 12, the chamber 8 is opened through the atmospheric passage 1B, the gap between the valve body 12 and the second valve seat 17, and the passage 14, as will be described in detail later. Atmospheric pressure is introduced into the engine, thereby causing the power piston 5 and the output shaft 19 to advance, thereby generating high brake fluid pressure in a master cylinder (not shown) provided in front of the power piston 5 and the output shaft 19.

However, in this embodiment, a bellows-like telescopic boot 20 provided between the end of the rear shell 3 and the end of the cylindrical portion 5a is used, and the end of the boot 20 is connected to the end of the input shaft 16 in the axial direction. A storage section 20a extending from the top to accommodate the filter 21 and an end wall section 20b having a communication port 22 opened in the center are successively formed.

A filter 21 is housed in the housing portion 20a, and a valve plate 23 made of an elastic body is disposed outside the filter 21.

This valve plate 23 is slidable with respect to the input shaft 16, and its outer peripheral portion is brought into elastic contact with the inner surface of the end wall portion 20b due to the elasticity of the filter 21, thereby closing the communication port 22. Furthermore, the elasticity of the valve plate 23 and the filter 21 is limited to at least the housing portion 20a of the boot 20 and the end wall portion 20.
The elasticity is set to be softer than that of b.

Therefore, when the vacuum booster 1 is operated, when the chamber 8 is communicated with the atmospheric passage 18 by the valve mechanism 11, the pressure inside the atmospheric passage 18 decreases, and a pressure difference is generated between the inside and outside of the valve plate 23, and the valve mechanism 11 causes the chamber 8 to communicate with the atmospheric passage 18. The air outside the plate 23 passes through the outer periphery of the valve plate 23 through the filter 2.
The air flows through the filter 21 as shown by arrow A from the gap between the valve plate 23 and the end wall 20b, and flows into the atmospheric passage 1B.

At this time, conventionally the air flowing through the filter was flowing through the filter through the shortest distance as shown by arrow B.
In particular, a loud suction noise was generated immediately after the operation of the vacuum booster 1, which requires a large amount of air, but the air flow path (arrow A) in this embodiment is bent and long within the filter 21. Therefore, it is possible to satisfactorily absorb the sound energy of the air flowing therethrough and suppress the generation of loud intake noise.

Moreover, at that time, the flow path area between the valve plate 23 and the end wall 20b is automatically changed in size depending on the pressure difference generated inside and outside the valve plate 23, so that the inflow of air is restricted and the vacuum boost is increased. The responsiveness of the device 1 will not deteriorate.

Note that, as shown by the dotted line, a hole 24 may be formed in either or both of the storage portion 20a and the valve plate 23.

These holes 24 allow air to be supplied therefrom when a small amount of air is required without substantially producing suction noise, and therefore the valve plate 23 at such times
It is possible to prevent bending of the material and improve its durability.

Further, in the above embodiment, the storage portion 20a and the end wall portion 20b
Although these are integrally formed in the boot 20, they do not necessarily have to be integral, nor do they need to be made of an elastic body.

Furthermore, the valve plate 23 does not necessarily have to be an elastic body.Although the present invention has the above configuration, it is possible to reduce air intake noise without impairing the responsiveness of the vacuum booster. This effect can be obtained.

In addition, if a part of the filter becomes clogged due to long-term use, the opening of the valve plate that opens in response to the pressure difference will automatically increase to ensure a large flow path area. It is also possible to prevent deterioration in the responsiveness of the vacuum booster due to clogging over a long period of time.

[Brief explanation of drawings]

The figure is a longitudinal sectional view showing an embodiment of the present invention. 1...Vacuum booster, 2,3...Shell, 5...Power piston, 5a...Cylinder part, 1B...Atmospheric passage, 20...
Boots, 20a...storage section, 20b...end wall section,
21...Filter, 22...Communication port, 23...Valve plate.

Claims (1)

[Scope of utility model registration request] In a vacuum booster, a retractable boot is installed between the shell and the cylinder of the power piston, and the inside of the cylinder is used as an atmospheric passage. A terminal wall portion having a communication port opened therein is successively connected to the end wall portion, and the atmospheric passage is communicated with the atmosphere through the filter housed in the storage portion and the communication port, and a valve plate is provided on the outside of the filter. The outer periphery of the valve plate is placed in elastic contact with the inner surface of the end wall where the communication port is opened, and when a pressure difference is generated inside and outside the valve plate due to the operation of the vacuum booster, the pressure difference causes A muffling device for a vacuum booster, characterized in that the outer circumference of the plate is separated from the inner surface of the end wall.