Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-05-07
2001-04-10
Schwartz, Christopher P. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S113400, C303S119200
Reexamination Certificate
active
06213568
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic brake system for automotive vehicles operable by independent force which includes a master brake cylinder preceded by a hydraulic brake force booster that has a booster piston and a working chamber to which an auxiliary pressure source is connectable, wherein a valve device operable by way of an electromagnetic drive is provided which establishes a hydraulic connection between the working chamber and an unpressurized pressure fluid supply reservoir in a first switching position and a connection between the working chamber and the auxiliary pressure source in a second switching position.
A brake system of this type is disclosed in German patent No. 32 41 662, for example. Preferably, the valve device of the prior art brake system comprises one normally open and one normally closed electromagnetic valve which are configured as digitally operated valves which are actuated by maximum openings of different length (pulse width modulation) and, thus, are less appropriate for controlling or dosing the hydraulic pressure introduced into the working chamber.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to improve upon a hydraulic brake system operable by independent force of the type mentioned hereinabove to such effect that a comfortable response behavior is ensured and the noises occurring during operation are reduced simultaneously.
Another objective is that the valve device have very small dimensions, and permit quick initial braking, on the one hand, and a sensitively controlled volume delivery in the normal braking mode, on the other hand.
According to the present invention, this object is achieved because the valve device is configured as a slide valve of analog operation.
To render the idea of the present invention more specific, the slide valve is configured as a slide guided in a sleeve-shaped housing member and having two control edges, the first control edge along with a corresponding control edge on the housing member providing a first variable throttle cross-section which controls the hydraulic connection between the working chamber and the unpressurized pressure fluid supply reservoir, and the second control edge along with a second control edge on the housing member provides a second variable throttle cross-section which controls the hydraulic connection between the working chamber and the auxiliary pressure source.
In a preferred aspect of the present invention, the slide has a hollow design and includes a bore which permits a connection between a port associated with the auxiliary pressure source and a port associated with the working chamber. According to the present invention, this achieves a pressure compensation on both sides of the slide so that the electromagnetic drive may be correspondingly reduced in dimensions. The present invention also provides the possibility of using one type of multi-way valve for different vehicle classes.
Advantageously, a slot-type seal is produced between the port associated with the auxiliary pressure source and the port associated with the pressure fluid supply reservoir. The slot-type seal is formed by the radial clearance between the slide and the housing member. To increase the reliability in operation of the mentioned seal, a sealed contact joint, preferably configured as a biassed elastomeric, especially teflon seal, is arranged in series with the slot-type seal.
According to a preferred aspect of the present invention, the separating effect of the second throttle cross-section is increased because the second control edge on the slide, in conjunction with a stop designed as a sealing seat, forms a seat valve which is serially connected with the second throttle cross-section.
The stop which preferably determines the first switching position or the initial position of the slide may be configured as a conical or spherical seat, for example, or by an elastomeric ring element, for example, an O-ring.
In order to control disturbing friction forces in another preferred aspect of the subject matter of the present invention, a means is provided which permits sensing the slide position and having its output signals adapted to be supplied to an electronic controller which influences the electromagnetic drive. It is especially appropriate when the electromagnetic drive is configured as a proportional magnet.
The reliability in operation of the brake system of the present invention is enhanced in a particularly favorable manner in that a non-return valve which closes towards the pressure fluid supply reservoir is inserted into the valve device in the connection between the working chamber and the pressure fluid supply reservoir. Besides, it is expedient when the second control edge after lifting from the sealing seat still overlaps the second control edge of the housing member and will not open the second throttle cross-section until the second control edge has passed.
Further features, advantages and details of the present invention can be seen in the attached patent claims and the illustration and subsequent description of a preferred embodiment of the brake system of the present invention. In the accompanying drawings,
REFERENCES:
patent: 3880476 (1975-04-01), Belart et al.
patent: 5018797 (1991-05-01), Takata
patent: 5109886 (1992-05-01), Takata et al.
patent: 5127435 (1992-07-01), Takata et al.
patent: 5234030 (1993-08-01), Kervagoret et al.
patent: 5492394 (1996-02-01), Kusano et al.
patent: 5531509 (1996-07-01), Kellner et al.
patent: 19 41 098 (1971-02-01), None
patent: 22 62 247 (1974-06-01), None
patent: 32 41 662 (1984-05-01), None
patent: 36 26 292 (1988-02-01), None
patent: 40 34 839 (1992-03-01), None
patent: 44 43 373 (1995-06-01), None
patent: 44 30 168 (1996-02-01), None
patent: 195 18 333 (1996-11-01), None
patent: 0 441 543 (1991-08-01), None
patent: 0 524 032 (1993-01-01), None
patent: 0 607 451 (1994-07-01), None
patent: 2 267 543 (1993-12-01), None
Patents Abstracts of Japan No. 61196852, published Sep. 1, 1986.
Continental Teves AG & Co. oHG
Rader & Fishman & Grauer, PLLC
Schwartz Christopher P.
LandOfFree
Hydraulic braking system operated by extraneous force does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic braking system operated by extraneous force, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic braking system operated by extraneous force will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2510343