| 摘要 |
In the context of an antilock system functioning on the outflow principle for a dual-circuit brake system of a motor vehicle, a top-up device is provided which throughout pressure reduction phases of the ABS control provides for the topping-up of brake fluid in the tandem master cylinder of the brake system. A topping-up valve is provided for each brake circuit, which valves in their open positions each connect one of the outlet pressure chambers of the tandem master cylinder to an accumulator constantly maintained at a high outlet pressure, which accumulator can be charged from the brake fluid reservoir. The topping-up valves are separately or jointly switched into their open position at least as long as a pressure reduction phase of the ABS control is under way on at least one of the wheel brakes of the respectively assigned brake circuit. The flow factors of the pressure reduction flow paths leading to the reservoir by way of the brake pressure control valves and of the top-up flow paths leading by way of the topping-up valves are so designed by virtue of the construction of these valves that, per unit time, at least that quantity of brake fluid is topped up which flows back into the reservoir during a pressure reduction phase.
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