JPS58110359A - Booster for brake - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a booster (2) mainly used in a vehicle brake system and provided between a pedal mechanism operated by a driver and a master cylinder of the brake system.

Such boosters typically include a housing containing a servo device operatively connected to a low pressure source such as an engine inlet manifold, the housing including valve means for controlling operation of the booster, and a control coupled to a pedal mechanism for actuating the valve means. It has an axial extension through which the rod passes. The extension also includes an air flow path from the atmosphere to the housing, and in order to dampen the undesirable noise resulting from the rapid air flow through this flow path, foam was previously used that surrounded the rod and engaged around the circular surface of the extension. It has been proposed to provide one or more silencers in the form of annular bushers of material.

This previous proposal has proven unsatisfactory because the filter forms a flow barrier, significantly restricting the amount of air passing through the flow path and reducing booster response time. This problem is particularly acute in tandem boosters because the tortuous flow path between their inner chambers makes them more sensitive to air restriction than single-circuit boosters. The control rod is usually provided (3) with a limited oscillating movement in the lateral direction of the extension, thereby tending to move the peripheral washer silencer radially, which causes the control rod to move against the peripheral inner wall of the extension or of the rod. Another problem arises as air moves away from the outer surface or both, allowing it to leak through the washer. This causes high-frequency squealing noises that can be bothersome to people inside the vehicle since the booster extension's air inlets are often on the passenger side of the vehicle's main forward bulkhead.

It is an object of the present invention to provide an improved booster that avoids the above-mentioned problems.

According to the present invention, a booster mainly used in a vehicle brake system includes a housing that includes a servo device and is connected to an operating pressure source, and a control rod that protrudes from the housing and extends from the housing that is connected to a pedal mechanism operated by a driver. an axial extension operative to provide communication between the atmosphere and the housing; further including a sound damping device within the extension having an outer surface surrounding the rod and joining about the inner surface of the extension; The device also defines an uninterrupted passage therein extending generally in the longitudinal direction of the rod and provides an air flow path through the sound deadening (4) device.

The muffling device is preferably made from a foam material, the foam preferably being of the reticulated type. Reticulated foam is a particularly useful sound deadening material because the large number of differently sized interconnected cell openings in its surface are believed to act to filter different sound waves while air passes through the openings.

In one convenient embodiment of the muffler, the rod is provided with a number of apertures around the periphery, which contribute to the elasticity of the muffler, thereby increasing the ability of the device to accommodate swinging of the rod. do.

In another preferred construction, a single annular opening is provided in the center of the muffler and the rod is passed through it with a gap to form the flow path.

The invention will now be described by way of example with reference to the accompanying figures. The booster shown in FIG. Divide the No-Using into a pair of chambers in the traditional manner. The movable wall is operatively (5) connected to the output lot 2A and transmits the output to the master cylinder of the brake device. The member 2 has an integral tubular extension 3 projecting from the housing 1 and sealed thereto by a boot 4. A control rod 5 extends through the extension 3 and slides within the member 2 at its inner end, with a rubber washer 7 above the output rod 2.
It is connected to the piston B which acts through the The connection between the rod 5 and the piston B is such that the rod 5 is capable of a limited oscillating movement in the lateral direction of the extension 6. The structure thus far described with reference to FIG. 1 is conventional and its operation will be apparent to those skilled in the art.

The rod 5 emerges from the extension 6 through the filter part 8, and a silencer 9, preferably of reticulated foam material, is located inside the filter part 8 and presses against the support 1°, itself against the inner shoulder of the extension 6. is housed in.

2A and 2B show the silencer 9 in more detail. It has a tubular shape with an approximately circular cross section and an extension 6
(6) having a size for sealingly joining with the inner wall 6 of the circular 1 part, and having a series of approximately circular openings 11;
In this case, four ports are arranged symmetrically around the shaft 5 [
- is shown opening into the central hole 12 of the muffler through which the shaft 5 passes, and the intact inner wall portion of the hole 12 seals the shaft. The vent 11 has a relatively uninterrupted passage to allow air to pass through the extension during operation of the booster. Also, the multiple communicating gaps in the reticulated foam device reduce the different frequency noises occurring in the air passages of the device, thereby resulting in quieter operation.

Furthermore, the vents 11 also serve to increase the radial extensibility of the device so that it can more easily accommodate the normal lateral movements carried out by the rod 5 during operation of the booster. This reduces the tendency for the muffling device to be pulled away from the inner surface of the extension or away from the outer surface of the rod 5 during rocking of the rod 5, and the leakage and associated noise through the fruiting device is reduced. This is less likely to occur than with conventional muffling devices.

Due to the particular construction of the ports shown (7), some of the holes always remain almost completely open even when rocking of the rod partially blocks one or more ports; Provides free air passage.

A variation of the silencer is shown in Figures 3A and 6B. In this embodiment, six ports 11 are provided, but there may be at least more, and they are spaced radially inwardly from both the inner and outer circumferences of the device. This embodiment of the silencer has the same advantages as the previously described embodiments.

In another variant of the silencer shown in FIGS. 4A and 4B, a single annular opening 11 is provided and the inner circumference 13 of the device is
is spaced apart from the rod 5. R-shaped entrance 11
serves to provide an air flow path through the extension, which solves the problem of device weakness due to swinging of the rod due to spacing from the rod.

The number, shape and configuration of the vents 11 can be varied as desired (8) provided that sufficient air flow paths and stretchability of the device are achieved. The preferred material for the silencer is usually plastic reticulated foam, although other foamed and non-foamed materials may be included.

[Brief explanation of drawings]

Fig. 1 is a partially sectional side view of an embodiment of the booster of the present invention, Fig. 2A is an enlarged end view of an embodiment of the silencing device used in the booster of Fig. 1, and Fig. 2B is a longitudinal sectional view thereof. , FIGS. 3A and 3B are similar views to FIGS. 2A and 2B of a modified example of the silencer, and FIGS. 4A and 4B are views similar to FIGS. 2A and 2B of yet another modified example of the silencer. FIG. 1: Housing 6: Axial extension 5: Control rod 9: Silencer 11: Vent 12: Silencer central hole Patent applicant: Lucas Industries Public
Limited Company (9) FIG. FIG. 3B. FIG. 4B.

Claims (1)

[Claims] (1) A booster mainly for vehicle brakes,
a housing containing a servo device and connected to a source of actuating pressure; and an axial extension projecting from the housing and from which a control rod extends that connects to a pedal mechanism operated by the operator, the extension being connected to the atmosphere and the housing. further comprising a silencer having an outer surface surrounding the rod and joining around the inner surface of the extension;
The muffler is also formed in an uninterrupted aperture extending generally longitudinally of the rod, providing airflow through the muffler. (2. In the booster described in claim 1,
A booster whose silencer is made of foam material. (3) In the booster described in claim 1,
(1) (4) In the booster according to any one of claims 1 to 3, the silencer is provided around the rod. A booster containing a large number of passageways. (5) In the booster according to claim 4,
A booster whose opening opens into the central hole of the silencer through which the rod passes. (6) In the booster according to claim 4,
A booster in which the port is radially spaced from the rod and separated from the rod by the material of the device. (Force) In the booster of any one of claims 1 to 3, the silencer has a single central hole of larger diameter than the rod, the uninterrupted passage being arranged around the rod. Booster 0 left in