Power plants – Pressure fluid source and motor – Pulsator
Patent
1994-12-19
1996-07-30
Lopez, F. Daniel
Power plants
Pressure fluid source and motor
Pulsator
92107, 921694, B60T 1320
Patent
active
055400531
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an actuating unit for a hydraulic brake system for automotive vehicles, including a pneumatic brake power booster, which is preferably a vacuum brake power booster, and a master brake cylinder inserted after the brake power booster in terms of effect. The brake power booster includes a booster housing, the interior of which is subdivided into two chambers by a movable wall which is attached to a control housing accommodating a control valve, and a centrally arranged force-transmitting element being provided which is in force-transmitting connection with the master brake cylinder, on the one hand, and a vehicle body wall of the automotive vehicle, on the other hand.
An actuating unit of this type is disclosed in German patent DE 29 22 299. The force-transmitting element of the brake power booster of the prior-art actuating unit is provided as a carrying pipe with axial slots, through which the movable wall is coupled with a part of the control housing which is arranged inside the carrying pipe and actuates an output member transmitting the output force of the brake power booster.
What is considered least favorable in the referenced actuating unit is the complicated and costly way of transmitting forces from the movable wall to the output member, which is done by means of tabs provided on the movealble wall to the above-mentioned control housing part, in which the output member is held by way of a retaining ring screwed to the movable wall. For this reason, a tandem-type design would be possible only by very great structural efforts.
Another disadvantage is the considerable overall axial length and the comparatively high weight of the referenced actuating unit. The high weight is mainly due to the massive carrying pipe, made of metal, and the diaphragm plate, forming the movable walls which must be made of a thick material in order to transmit major boosting forces.
Finally, still another disadvantage is that the configuration of the carrying pipe depends on customer requests for flange patterns or vehicle-related flange patterns to mount the master brake cylinder to the booster housing and to mount the brake power booster to the vehicle body wall. Different carrying pipes are required for different combinations of flange patterns.
Therefore, an object of the present invention is to provide an actuating unit of the previously mentioned type with a design which permits reducing costs and weight. In addition, both the booster housing and the diaphragm plate should be made of an extremely thin sheet metal. Further, the application of control assemblies, which nowadays are typically rated for a plurality of booster sizes, with almost all component parts and in particular those requiring tools should be ensured without structural modifications. Still further, the invention is to provide a simple and inexpensive tandem-type design.
This object is achieved according to the present invention in that the force-transmitting element is a continuous bolt which extends in an axial direction through the control housing.
As in the past, the vacuum forces acting on the booster housing half closest to the vehicle body wall and the forces which are developed by a possible pulling of the actuating pedal or by an abrupt resetting movement of the brake pedal, are introduced into the vehicle body wall. All the other occurring forces are absorbed and transmitted by the central bolt under pressure and tension which does not depend on the desired flange pattern.
Due to a favorable improvement provided by the present invention, the operating safety is increased by means of the valve piston having a sleeve-shaped design. The sleeve-shaped valve piston is guided on the bolt and, with its end, supported at the actuating pedal. The preferred embodiment provides a large guide length for the valve piston so that the buckling risk is eliminated as far as possible.
Another embodiment of the present invention, in which the brake power booster includes an elastic reaction disc which
REFERENCES:
patent: 3040535 (1962-06-01), Randol
patent: 4307570 (1981-12-01), Yardley
patent: 4418611 (1983-12-01), Tateoka et al.
ITT Automotive Europe GmbH
Lopez F. Daniel
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