Expansible chamber devices – With inspection window in expansible chamber wall portion – With lock
Patent
1992-10-06
1993-08-03
Denion, Thomas E.
Expansible chamber devices
With inspection window in expansible chamber wall portion
With lock
91 1, F01B 2526, F01B 3112
Patent
active
052319130
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is related to a process for the adjustment of a travel sensor for a vacuum brake booster for automotive vehicle brake systems having an anti-locking device. The electrical travel sensor monitors the position of a movable wall which furnishes the boosting power of the vacuum brake power booster. In particular, the invention relates to a process for the adjustment of the desired axial distance between an actuating element of the travel sensor and the movable wall.
It is, for example, known from the German patent application published without examination, No. 3,731,603, corresponding to U.S. Pat. No. 4,826,255, to sense the position of the movable wall in order to safeguard the regular functioning of brake systems with anti-locking device which work as "open" systems. U.S. Pat. No. 5,141,295 filed on Dec. 19, 1989 assigned to the assignee of this application also describes such movable wall sensor for a brake power booster for this purpose.
In these arrangements, a rotary hydraulic pump is provided, which, in one control mode, aspirates hydraulic fluid out of an unpressurized supply tank, and with the wheel valves in the closed condition, delivers the same into the master brake cylinder in order to properly position the brake pedal. For this purpose, a travel sensor, for example, a travel-controlled electric switch, is envisaged which supplies an electrical signal depending on the position of the movable wall to an electronic control system which controls the pumping rate of the pump.
The vacuum brake power booster, in particular its housing, is subject to sizable working tolerances which have a negative effect on the functioning of the travel sensor and, in an extreme case, may even lead to the total failure of the brake system.
It is, therefore, the object of the invention to provide a process for the adjustment of the exact position of the electrical travel sensor in respect of the movable wall of a vacuum brake power booster, which affords a virtual elimination of the influence of its working tolerances on the functioning of the travel sensor.
SUMMARY OF THE INVENTION
According to the invention, this object is achieved by the following process steps:
a) installing a stop in the booster housing for the output member driven by the booster movable wall, the stop having a defined length;
b) applying a vacuum to the vacuum chamber in the booster housing;
c) actuating the vacuum brake power booster by applying a predetermined input force which shifts the position of the movable wall to abut the output member with the stop and bring the movable wall to a test location;
d) determining the distance between a reference surface at the booster housing and the movable wall at the test location;
e) comparing the distance in step d) to a distance from a reference surface of the travel sensor to the tip of an actuating element with the tip located at a point located so that the travel sensor signal output corresponds to the test location of the movable wall;
f) installing the travel sensor in the booster housing while locating the travel sensor reference surface by means of the booster housing reference surface using a suitable spacing means to locate the tip of the actuating element at the test location of the movable wall with said travel sensor actuating element set in said travel sensor at said location corresponding to said test location.
The spacing means employed can be the selection of a replaceable tip sized to create the appropriate spacing distance.
Another spacing means can be provided by selecting a properly sized holder installed in the booster housing with the travel sensor assembled into the holder. The holder can also be adjustable to vary the location of the installed travel sensor. By these two latter operations an exchange of the travel sensor will be simplified, and the advantage offered by this approach consists in that in this case, the adjustment is carried out at the brake power booster whose condition is no longer changed. In the former approach usin
REFERENCES:
patent: 4365538 (1982-12-01), Andoh
patent: 5141295 (1992-08-01), Burgdorf et al.
Reinartz Hans-Dieter
Risch Stefan
Steffes Helmut
Alfred Teves GmbH
Denion Thomas E.
Lewis J. Gordon
Seitter Robert P.
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