Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1992-12-03
1994-11-08
Butler, Douglas C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
3031161, 3031191, B60T 848
Patent
active
053621409
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention pertains to an automotive vehicle brake system providing brake slip control and traction slip control. A brake system of this type is known from German Published Patent Application No. 36 35 846. In order to minimize the number of valves required for traction slip control, it is there suggested to provide a locking valve in each connection line from the pressure medium storage reservoir to the tandem master cylinder if the brake circuit associated with this connection line has a driven wheel. During a traction slip control phase, the locking valves are closed and, via a pump, pressure is built up in the brake circuit of the driven wheel while the locking valve prevents pressure medium from escaping into the storage reservoir. In these systems, only one such locking valve is required in the case of a one-axle drive and of a front-axle/rear-axle brake circuit allocation. In this case, this single locking valve is required for the brake circuit of the driven axle. For all-wheel drive vehicles and for vehicles with diagonal brake circuit allocation, one valve is not sufficient since both brake circuits have driven wheels. The arrangement and number of the valves required thus depends on the number of driven wheels as well as on brake circuit allocation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a brake system that, with a minimum number of locking valves, is equally suited for traction slip control regardless of the type of brake circuit allocation.
This object is achieved by pressurizing the first working chamber of the master cylinder, while isolating the brake circuit associated with the first working chamber by using a locking valve during a traction slip control operation. From the resulting pressure increase in the first working chamber, the floating piston is displaced towards the second working chamber. This displacement of the floating piston results in a pressurization of the second working chamber and its associated braking circuit.
At the beginning of a traction slip control operation, the respective wheel brake must be filled with pressure medium (or pressure fluid). By making use of the floating piston function, a second locking valve becomes superfluous because of the floating piston travel towards the second working chamber. During such travel, the port of the pressure medium storage reservoir to the secondary brake circuit becomes closed as in a normal braking operation so that the pressure variation in the secondary brake circuit is controlled in correspondence with that of the primary brake circuit. As long as they are under pressure, the brake circuits will remain separate due to the pressure transmission only via the floating piston.
There are also known suggestions to admit pressure medium into the chamber upstream of the two pressure chambers of the tandem master cylinder or, if applicable, into the hydraulic brake power booster (GB 2,168,771 A) and, in both brake circuits, to control the communication towards the pressure medium storage reservoir via the two valves provided in the tandem master cylinder, which are controlled by the piston strokes. This circuitry, however, would have impacts on the brake pedal and would irritate the driver in case of a sudden pedal-initiated braking operation.
Suitable for the inventive solution of the objects set forth are both tandem master cylinders with so-called central valves and tandem master cylinders equipped with sealing cups through which pressure medium enters the brake circuits.
The inventive principle is not confined to so-called open systems but is also applicable to closed systems or plunger systems. Thus, this invention will work no matter what kind of device--e.g., pumps or pistons--is used to effect a pressure build-up or to reduce the pressure in case of brake slip control.
On principle, there always exists the possibility to make use of an additional pump or of another pressure generator for building up pressure in the primary circuit during trac
REFERENCES:
patent: 4405183 (1983-09-01), Resch
patent: 4660897 (1987-04-01), Leiber
patent: 4685747 (1987-08-01), Belart et al.
patent: 4743075 (1988-05-01), Belart et al.
patent: 4779937 (1988-10-01), Burgdorf et al.
patent: 4840436 (1989-06-01), Burgdorf et al.
patent: 5044702 (1991-09-01), Beck et al.
patent: 5054861 (1991-10-01), Resch
patent: 5219442 (1993-06-01), Burgdorf et al.
patent: 5251971 (1993-10-01), Reinartz et al.
Alfred Teves GmbH
Butler Douglas C.
Lewis J. Gordon
Seitter Robert P.
LandOfFree
Automotive vehicle brake system with brake-slip-dependent and tr does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automotive vehicle brake system with brake-slip-dependent and tr, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automotive vehicle brake system with brake-slip-dependent and tr will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1777732