Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1995-02-16
1996-07-30
Graham, Matthew C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
303 842, 303DIG2, B60T 826
Patent
active
055404871
DESCRIPTION:
BRIEF SUMMARY
The present invention is concerned with an anti-locking hydraulic brake system comprising a brake force controller, of the type as set out in the preamble portion of the main claim.
A variety of brake systems of the afore-mentioned type are widely known in the art. For example, DE-37 42 173 describes an anti-locking brake system which has mounted in the rear axle brake circuit a brake force controller which, with the aid of an electromagnetic blocking device, is rendered inoperative as long as the anti-locking means is performing its function. However, should a defective condition occur on the anti-locking device, the blocking means would be released, thereby causing the brake force controller to assume its pressure reducing function in each decelerating step. This will insure that also upon failure of the electronic brake pressure control the rear wheels will be prevented from locking before the front wheels in the event of a pedal deceleration, thereby attaining over brake systems having no brake force reducer enhanced driving stability in case of a failure of the anti-locking function, involving, however, the disadvantage that additional electrical conduits and control signals arerequired to insure the function of the brake force controller. Moreover, consideration should be given to the fact that a failure of the anti-locking function constitutes an exceptional condition and tha actuation of the brake force controller should, if possible, never be needed. If a defective condition does occur in years, the brake force controller may become unserviceable having got stuck in a blocked position due to contamination or jamming.
It is, therefore, the object of the present invention to provide a brake system of the afore-mentioned type requiring no additional electronic elements for the brake force controller and insuring in case of a failure, through the brake force controller, even after a long-standing service, a pressure reduction.
This problem, in the practice of the invention, is solved by the characterizing features or the main calm. Hence, according to the principle underlying the invention the brake force controller starts to perform its pressure reducing function in each uncritical deceleration step once the switch-over pressure is exceeded, and continues to operate as long as the brake slip values are within the non-critical range. However, once an excessive brake slip is determined causing commencement of the anti-locking function of the brake system the brake force controller, through a blocking device, is rendered inoperative, thereby initiating the electronically controlled brake pressure control. Actuation ot the blocking device by the pump outlet pressure will eliminate the need to provide an additional electrical feed-in conduit and corresponding electronic signals.
By mounting the brake force controller directly on the wheel brake into the circuit, a conventional valve block can be readily used without requiring any additional modifications. The brake force controller can be mounted on the wheel brake.
Assembly will be easier if the brake force control is designed as a screw-in control involving minor space requirements only.
Additional advantageous features will become manifest from the following description of three drawings, wherein:
FIG. 1 shows a brake system of the invention;
FIG. 2 shows a brake force controller provided for a brake system accoruing to the invention;
FIG. 3 shows another form of embodiment of a suitable brake force controller.
The brake system of FIG. 1 operates on the reflux principle. The brake circuit division is of a diagonal configuration resulting in an identical design of brake circuits I and II. For this reason, only brake circuit II is shown herein for purposes of illustration.
In a pedal-actuated deceleration, the main brake conduit 3 is pressurized by the master brake cylinder 1 in communication with the pressure fluid reservoir 2. Such a pressure propagates in the branch brake conduits 4 and 5 and the supply lines 8 and 9 leading to the wheel brakes 10 and
REFERENCES:
patent: 4898430 (1990-02-01), Becker-Endrigkeit et al.
patent: 4969697 (1990-11-01), Lindenmann
patent: 5209552 (1993-05-01), Reinartz et al.
Beck Erhard
Reinartz Hans-Dieter
Volz Peter
Graham Matthew C.
ITT Automotive Europe GmbH
Lewis J. Gordon
Twomey Thomas N.
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