Wabco Gmbh

Wabco Westinghouse Fahrzeugbremsen Gmbh

Harald Koster

Hartmut Rosendahl

Konrad Rode

Frank Zielke

Otto Friederichs

Helmut Pannbacker

Henrich Riedemann

Wolfgang Hinz

A process for reducing the yawing moment that develops during hard braking in a vehicle equipped with an anti-lock braking system (ABS) and traveling on a roadway having different coefficients of friction on opposite sides of the vehicle is disclosed. The driver must compensate for the yawing moment by steering towards the side that has the lower coefficient of friction. The process comprises venting the brake cylinder of the front wheel on the side with the higher coefficient of friction for a time t.sub.AH that is calculated in an electronic control module. The algorithm for computing t.sub.AH depends on the venting time t.sub.AL at the front wheel on the side with the lower coefficient of friction and the maximum or so-called deregulating pressures attained in the cylinders of the rear wheels. The electronic control module receives pressure information from pressure sensors and ascertains the venting time t.sub.AL that the ABS produces at the slipping front wheel. The algorithm used by the electronic control module attenuates the yawing moment in a way that adapts automatically to changing road conditions and vehicle types or loads. This contributes to a shortening of the overall braking distance while maintaining controllability of the vehicle.

Process for attenuating the yawing moment in a vehicle with an anti-lock

A process for reducing yaw during braking in a vehicle having an anti-lock braking system (ABS) and traveling on a roadway having different coefficients of friction on opposite sides of the vehicle, is disclosed. The process comprises detecting the braking pressures in the wheels of the vehicle, calculating a permissible braking pressure difference, and adjusting the braking pressures in the wheel on the high friction side (high wheel) so as to maintain the permissible braking pressure difference. The permissible braking pressure difference is a variable value which depends mainly on the deregulating pressure (P.sub.max) at which the ABS begins to deregulate in the low wheel.

A process is disclosed for restoring brake pressure in a brake of a motor vehicle having an antilock brake system which subjects the brake to a brake regulating cycle. The brake regulating cycle comprises a pressure reduction phase, wherein the brake pressure is reduced from a deregulating pressure P.sub.max to a holding pressure P.sub.min, a pressure maintenance phase, wherein the holding pressure P.sub.min is maintained in the brake, and a pressure restoration phase, wherein the brake pressure in the brake is increased. According to the invention, during the pressure restoration phase the brake pressure is increased with a steep pressure gradient PG.sub.H during a first pressure increase stage until a pressure level P.sub.K is reached. Thereafter the brake pressure is increased with a low pressure gradient PG.sub.N in a second pressure increase stage. The steep pressure gradient PG.sub.H is calculated as a function of P.sub.max and P.sub.min of the last regulating cycle, while the low pressure gradient PG.sub.N is calculated as a function of P.sub.max of the last regulating cycle. Alternatively, PG.sub.H is calculated as a function of the average value of P.sub.max and P.sub.min for several previous regulating cycles, while PG.sub.N is calculated as the average value of P.sub.max for several previous regulating cycles.

Process for the restoration of brake pressure in a motor vehicle with

A method is provided for at least approximately determining the frictional value utilized between a wheel and the roadway. The method uses a vehicle weight that is determined, at least approximately, and a momentary actuating energy of a brake that is determined during a braking action. The method calculates the frictional value from the momentary actuating energy, the vehicle weight, and the wheel braking factor. In another embodiment, the method determines, at least approximately, the momentary vehicle deceleration. The frictional value is calculated from the momentary vehicle deceleration during braking and the Earth's gravitational acceleration.

Process to determine the utilized frictional value between wheel and

An automatic control logic for an anti-lock protected vehicle braking plants is provided for all-terrain operation. In this case, the standard automatic control logic for road operation is switched, by the driver with an all-terrain switch (13) to a special automatic control logic for all-terrain operation. The special automatic control logic generates time periods, during which a short-term blocking of the automatically controlled wheels (12) is intentionally permitted. The locking time periods have a time duration of about 240 ms. The braking distance of the vehicle in cross-country terrain is shortened while a sufficient cornering force remains based on the all-terrain automatic control logic.

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Hannover, Germany

Harald Koster