Expansible chamber devices – Cylinder detail – With reinforcing member
Reexamination Certificate
2002-11-12
2004-08-10
Look, Edward K. (Department: 3745)
Expansible chamber devices
Cylinder detail
With reinforcing member
C091S379000
Reexamination Certificate
active
06772674
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to vehicle brake systems, and more particularly to vacuum boosters for vehicle brake systems.
BACKGROUND OF THE INVENTION
Vehicles such as automobiles, trucks, buses, and motor homes typically include a dashboard at the front of the passenger compartment, having a power brake booster on the front of the dashboard connected by a push rod to a brake pedal mounted on the rear of the dashboard in the passenger compartment. A brake master cylinder, connected to the braking system, is mounted on the front end of the booster.
As shown in
FIG. 1
, one commonly used type of brake booster
10
, known as a vacuum booster, includes a housing apparatus
12
having a front housing
14
and a rear housing
16
, joined together and defining a longitudinal axis
18
of the booster
10
. The front housing
14
defines a front wall
20
of the housing
12
and an inner surface
22
of the front wall
20
. The rear housing
16
defines a rear wall
24
of the housing
12
and an inner surface
26
of the rear wall
24
.
A tie rod
28
extends axially through holes
25
,
27
in the front and rear walls
20
,
24
respectively of the housing
12
. The tie rod
28
has a first end
30
engaging the rear wall
24
of the housing
12
, and a second end
32
engaging the front wall
20
of the housing
12
. The first end
30
of the tie rod
28
includes an annular flange
36
welded or mechanically fastened to the inner surface
26
of the rear wall
24
, and a threaded section
34
extending from the annular flange
36
, through the hole
27
in the rear wall
24
, for mounting the booster
10
on the front of a vehicle dashboard. The second end
32
of the tie rod
28
extends through the hole
25
in the front wall
20
of the housing
12
, and is also threaded to receive a special sealing nut
38
that bears against the inner surface
22
of the front wall
20
. The threaded portion of the second end
32
of the tie rod
28
extends outward beyond the front wall
20
of the booster
10
, for mounting a brake master cylinder to be actuated by the booster
10
.
During assembly of the booster
10
, the position of the sealing nut
38
on the threads at the second end of the tie rod
28
is adjusted so that once the front and rear housings
14
,
16
are joined together, the sealing nut
38
will be properly positioned for applying an axially directed force against the inner surface
22
of the front wall
20
of the housing
12
to achieve a desired axial distance between the front and rear walls
20
,
24
of the housing
12
. Setting the front and rear walls
20
,
24
at a desired axial distance is required to allow proper pre-load of the front and rear housings
14
,
16
, and proper spacing between internal components of the booster
10
, such as the booster piston
40
and a first and second diaphragm support
42
,
44
that move with the piston
40
, so that the booster
10
can function properly.
The booster
10
, of
FIG. 1
, is a tandem vacuum brake booster having a primary and a secondary diaphragm
46
,
48
, and a divider
41
that separate the interior of the housing
12
into primary and secondary vacuum chambers
50
,
52
, and primary and secondary high-pressure chambers
51
,
53
. These chambers must be sealed from one another for proper operation of the booster
10
. Air tubes
54
, adapted for sealing engagement with the primary diaphragm
46
and the divider
41
of the booster
10
, provide sealed passageways for the tie rod
28
to pass through the primary vacuum and high pressure chambers
50
,
51
, without allowing leakage along the tie rod
28
between the primary vacuum and high pressure chambers
50
,
51
. A sliding seal
55
, between the secondary diaphragm
48
and the tie rod
28
, precludes leakage around the tie rod
28
between the secondary vacuum and high pressure chambers
52
,
53
. Maintaining the proper positioning of internal components, such as the air tubes
54
, while adjusting the position of the sealing nut
38
on the tie rod
28
, further complicates the process of setting the proper distance between the front and rear walls
20
,
22
of the booster
10
.
What is needed, therefore, is an improved method and apparatus for setting and maintaining the axial distance between the front and rear walls of a booster housing in a vacuum booster of the type described above.
SUMMARY OF THE INVENTION
Our invention provides a tie rod apparatus and method for adjusting the axial distance between the front and rear walls of the booster, from outside of the booster, after the booster has been assembled.
In one form of our invention, a vacuum booster includes a housing having a front housing and a rear housing joined together and defining a longitudinal axis of the booster. The front housing defines a front wall of the housing and an inner surface of the front wall. The rear housing defines a rear wall of the housing and includes a captive nut having threads adapted for threaded engagement with a threaded end of a tie rod. The front and rear walls are spaced an axial distance from one another along the longitudinal axis. A tie rod extends axially through the housing and has a first end engaging the rear wall of the housing and a second end engaging the front wall of the housing. The first end of the tie rod has threads for engaging the threads of the captive nut in the rear wall of the housing. The second end of the tie rod has an axially facing surface thereof for applying an axially directed force against the inner surface front wall of the housing. The axial distance of the housing between the front and rear walls of the housing is adjusted by turning the tie rod, to thread the first end of the tie rod farther in or out of the captive nut.
In another form of our invention the booster includes internal elements thereof axially separating the interior of the housing into fluid chambers sealed from one another, and the captive nut includes a tube extending axially therefrom along a part of the tie rod into the interior of the housing through one or more of the fluid chambers. The tube has a surface adapted for sealing engagement with the internal elements of the booster.
The foregoing and other features and advantages of our invention are apparent from the following detailed description of exemplary embodiments, read in conjunction with the accompanying drawing. The detailed description and drawing are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.
REFERENCES:
patent: 4418611 (1983-12-01), Tateoka et al.
patent: 5487327 (1996-01-01), Schluter et al.
patent: 5765468 (1998-06-01), Gautier et al.
patent: 6164183 (2000-12-01), Fulks et al.
patent: 6209442 (2001-04-01), Haerr et al.
patent: 6374721 (2002-04-01), Zehnder, II et al.
patent: 6637837 (2003-10-01), Petin et al.
patent: 10136379 (2002-12-01), None
patent: 0760319 (1997-03-01), None
patent: 0061416 (2000-10-01), None
Kasselman Michael A.
MacLellan Patrick T.
Vermoesen Michel J.
Delphi Technologies Inc.
Leslie Michael
Look Edward K.
Smith Michael D.
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