JPS5917730Y2 - vacuum booster - Google Patents

Description

[Detailed description of the invention] This invention relates to a vacuum booster used for the purpose of reducing the operating force of vehicle brakes, clutches, etc., and in particular, by improving the mounting structure of the boot to the annular valve housing. This invention relates to a vacuum booster in which an annular valve housing is made smaller in the axial direction.

FIG. 1 shows an example of a conventional brake booster as the booster, in which the annular valve housing 4 of the power piston 3, which is slidably fitted into the shell 1 via the seal 2, is connected to the shell 1. It protrudes from the opening 5, and the protruding portion is covered with a boot 6.

The shell side end of this boot 6 is connected to the shell 1 by a bead.
A retainer 7 is attached to the end of the annular valve housing on the side of the annular valve housing, and this retainer 7 is fitted to the outer circumferential surface of the outer end of the annular valve housing 4.

By the way, devices that protrude toward the driver's seat, such as a brake booster, need to be made as small as possible in order to expand the space in the driver's seat.

In FIG. 1, the amount of protrusion of the brake booster toward the driver's seat is determined by the distance a from the mounting surface 8 of the shell 1 to the vehicle to the outer end of the boot 6. Distance C from to the outer end of seal 2, power piston 3
It is determined by the distance d determined by the stroke e and the mounting distance d between the boot 6 and the annular valve housing 4.

Looking at these lengths from the perspective of shortening a, if C is constant, b must maintain airtightness with the shell 1 even when the power piston 3 is at its most advanced position. Since it is determined by the basic performance of this device, it cannot be shortened, and there is a limit to shortening d as long as the above structure is adopted.

That is, in the conventional device, since the retainer 7 is fitted onto the outer peripheral surface of the annular valve housing 4, a certain distance limited by the axial dimension of the retainer 7 is required as the mounting allowance d. It was impossible to shorten.

In view of the above drawbacks, the present invention has been developed by fitting a retainer attached to the end of the boot on the annular valve housing side to the inner circumferential surface of the annular valve housing, which could not be shortened with conventional devices. Substantially eliminating the above installation cost d,
The valve housing is characterized in that the axial dimension of the annular valve housing is shortened.

The present invention will be explained below with reference to the illustrated embodiment. In FIG. 2, the retainer 10 has a cylindrical guide surface 10A and a flange I.
It is attached to the tip of the boot 6 with its cylindrical guide surface 10A facing inward, and the annular valve housing 4 is configured such that the outer surface of the flange IOB and the outer end surface of the annular valve housing 4 form the same plane. It is fitted into an annular groove formed on the inner peripheral surface of the valve housing 4.

FIGS. 3 and 4 show the shape of the retainer 10 as a single item. The cylindrical guide surface 10A has notched grooves 9 at a plurality of locations, and expands at an inclination angle α with respect to the cylindrical surface parallel to the axis. There is.

This device having the above configuration maintains the distance determined by the stroke e of the power piston 30 in FIG. This means that the distance has been shortened to the distance d' in FIG.

Further, if the retainer shape is set as in the embodiment, flexibility is generated in the cylindrical guide surface 10A, and the annular valve housing 4
This allows for easy press-fitting and secure fixation.

Note that the present invention can also be applied to other vacuum boosters, such as clutch boosters.

In this invention, by fitting the retainer to the inner circumferential side of the annular valve housing as described above, the installation cost between the boot and the annular valve housing can be shortened to the thickness of the boot, and the vacuum booster It is possible to reduce the size of the axial direction.

In addition, in the present invention, the inner periphery of the outer end of the boot is inserted into the inner flange of the ring-shaped retainer having an inverted cross-section, and the outer cylindrical guide surface of the retainer is inserted into the inner flange of the ring-shaped retainer, and Since the retainer is fitted into the annular groove formed on the inner circumferential surface of the retainer, the outer cylindrical guide of the retainer can be attached to the annular valve housing side end without using the elastic force of the boot itself. The close fitting engagement between the surface and the annular groove on the inner circumferential surface of the annular valve housing allows for reliable installation and good durability against heat and deformation over time.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional brake booster, Figure 2 is a sectional view of a brake booster according to the present invention, Figure 3 is a front view of the retainer, and Figure 4 is a side view of the retainer. be.

Claims (1)

[Scope of utility model registration request] A power piston that moves forward and backward in response to a pressure difference is housed in a shell, and the annular valve housing of the shaft of the power piston protrudes from the opening of the shell, and the annular valve housing extends from the outer end of the annular valve housing. In a vacuum booster in which the shell is covered up to the opening part with a boot, a ring-shaped retainer with an inverted cross section is provided at the end of the boot on the annular valve housing side, and the boot is attached to the inner diameter side flange of this retainer. The inner periphery of the end of the annular valve housing is fitted around the inner periphery of the retainer, and the outer cylindrical guide surface of the retainer is fitted into an annular groove formed on the inner periphery of the end of the annular valve housing. Vacuum booster.