Power plants – Pressure fluid source and motor – Pulsator
Patent
1990-12-17
1993-03-09
Look, Edward K.
Power plants
Pressure fluid source and motor
Pulsator
60588, B60T 1121, B62D 1108
Patent
active
051917653
DESCRIPTION:
BRIEF SUMMARY
INTRODUCTION
The present invention relates to a master cylinder for a hydraulic brake system and steering brake system for automotive vehicles, comprising a pair of master cylinders which are operable simultaneously for braking a vehicle and independently of one another for power steering, each being furnished with one pedal-operated piston that is slidably guided in a bore in the master cylinder housing and confines a pressure chamber, the said pressure chambers being in communication with an unpressurized pressure-fluid supply reservoir, being connectible to brakes on wheels on opposite sides of the vehicle and becoming interconnected through a compensating line when the master cylinders are actuated simultaneously and/or isolated from each other by way of a valve assembly when one of the master cylinders is actuated alone.
BACKGROUND OF THE INVENTION
A like master cylinder is known from German published patent application 32 19 042. In order to be able to connect the above-mentioned compensating line, the housing of the prior known master cylinder contains a radial outlet duct in which a compensating valve is arranged whose closure member closes and/or opens a compensating port terminating into the pressure chamber. To actuate the closure member, there is provision of a ball-shaped thrust member cooperating with the master cylinder piston and being guided in the compensating port at a distance from the closure member. At its front end, the housing of the known master cylinder contains a fill hole which represents a hydraulic connection between the pressure chamber and a pressure-fluid supply reservoir and is controllable by means of a feed valve operable by the master cylinder piston.
What has to be considered less favourable in the priorly known master cylinder are the comparatively high manufacturing and assembling costs which above all are due to the employment of several component parts which are required in particular for realising the feed valve and compensating valve.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to devise a master cylinder of the species initially referred to wherein the number of necessary component parts can be reduced.
This object is achieved according to this invention in that the compensating line connects to a compensating chamber adjoining the pressure chamber, and in that the valve assembly is formed by a sealing cup arranged on an operating piston that is actuatable by the primary piston.
To specify the inventive idea, it is suggested that a slope be designed at the transition from the pressure chamber to the compensating chamber, in whose and/or after whose area facing the pressure chamber the sealing cup is abutting.
A favorable improvement of the subject matter of this invention which lends itself to ease of manufacture and is reliably operating resides in that the compensating chamber is formed by a larger-diameter annular chamber which is designed in the bore and which is isolated from an unpressurized chamber sealing element arranged at the operating piston, the unpressurized chamber being confined by the bottom of the bore, on the one hand, and by a guiding collar designed on the operating piston, on the other hand, and in that the sealing element is designed as a second sealing cup which is arranged in an annular groove and whose flank averted from the compensating chamber is formed by the guiding collar. Improvement of the operating piston's guidance is accomplished owing to this measure.
Another advantageous improvement of this invention arranges for the operating piston to be provided with a stop which, on actuation, abuts on the master cylinder housing and is formed by an axial cylindrical extension of the operating piston which contacts the bottom of the bore.
In a master cylinder according to the species whose piston is furnished with a primary cup which, in the inactive position, is arranged at a distance from the port of a breather bore interconnecting the pressure-fluid supply reservoir and the pressure chamber, it
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patent: 3699679 (1972-10-01), Bardos et al.
patent: 4254624 (1981-03-01), Gaiser
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Alfred Teves GmbH
Lewis J. Gordon
Look Edward K.
Ryznic John
Seitter Robert P.
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