Wabco Gmbh

Wabco Westinghouse Fahrzeugbremsen Gmbh

Wabco Fahrzeugbremsen Gmbh

Konrad Rode

Hartmut Rosendahl

Harald Koster

Erwin Petersen

Frank Zielke

Klaus Lindemann

Otto Friederichs

Henrich Riedemann

Jurgen Eickhoff

Reinhard Schmidt

Siegfried Hofler

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 anti-lock braking system for a two-axle all-wheel drive vehicle having two intra-axle differentials and an engageable central inter-axle differential comprises a wheel sensor associated with each of the wheels for determining the rotational behavior of each of the wheels, and a four-channel electronic control circuit for providing individual wheel regulation. The electronic control circuit also detects whether the central differential is engaged or not and whether a malfunction has occurred in one of the channels. If one of the regulating channels has a malfunction and the central differential is not engaged, the electronic control circuit switches off regulation only in the malfunctioning channel. If, however, the central differential is engaged when a malfunction in one of the regulating channels has occurred, then the electronic control circuit switches off both the malfunctioning channel as well as an intact channel associated with a diagonally opposite wheel.

Anti-lock braking system for all-wheel drive vehicles

The invention is an apparatus for the acquisition of speed of rotation and/or angle of rotation signals on a shaft, on which there is a pulse transmitter on the circumference of the joint and a sensor which measures the pulses produced by the pulse transmitter located on a pivot part, which defines a pivot axis, around which the shaft portions of a cardan shaft can be pivoted in relation to one another.

Apparatus for the acquisition of speed-of-rotation and/or angle of

The invention relates to an electromagnetically-operated multi-way valve, which exhibits two valves (an inlet and an outlet) opposite one another. Corresponding to each of the two valves, there is an armature which interacts with a coil, located between the two valves. A coil bracket, disposed through the coil, has a passageway which, upon certain valve conditions, allows communication from the inlet valve to the outlet valve. One of the two valves can be activated against the force of a first spring by the first armature, and the other of the two valves can be activated against the force of a second spring by the second armature. The two springs are designed so that different magnetic forces are required to operate the two valves. The different magnetic forces are produced by a change of the current flowing in the coil. Since there is a separate armature for each valve, which can be operated by one current-controlled coil, it is possible to operate the two valves independent of one another.

Electromagnetically-operated multi-way valve

Sensor devices detect the dynamic response of each vehicle wheel to braking pressure and produce control signals if the associated wheel rapidly decelerates, slips, or accelerates. When braking pressure is initially applied, a deceleration control signal output from the sensor associated with a low friction wheel actuates, through a co-control logic circuit network, exhaust of braking pressure on both wheels on the corresponding axle. Shortly a period of fast application of braking pressure on both wheels occurs for a preselected time interval. This application is extended, for the co-controlled wheel only, for a shorter time period established by a timer through the logic network. After a holding period for both wheels, but at different pressure levels, a brief increase in braking pressure is actuated until another deceleration signal is output by the controlled wheel sensor. This actuates an exhaust of pressure in both wheels. However, the co-controlled wheel exhaust is normally of shorter duration since a subsequent slip control signal from the controlled wheel acts only to continue to exhaust that wheel's pressure. The periods of timed application, hold, and exhaust repeat as vehicle speed is reduced.

Process and apparatus for controlling the braking pressure in anti-skid

An antiskid control system for the individual regulation of fluid brake pressure at the respective wheels of a vehicle. The control system is modified so that a steering wheel experiencing high wheel/road adhesion is co-controlled during a cycle of wheel skid control at the steering wheel experiencing a low wheel/road adhesion value, such co-control being delayed at the onset of brake release at the low adhesion wheel, while the high adhesion wheel brake pressure is maintained constant to improve stopping distance.

Control system for improving the steering stability of motor vehicles

A switching circuit for preventing the velocity of the rotating wheels from exceeding the velocity of the moving vehicle in an anti-skid vehicular braking system. The switching circuit includes a first threshold device for generating deceleration and acceleration control signals and a second threshold device for generating positive and negative slip control signals. A logic circuit for evaluating the control signals and controlling the brake pressure and switching devices being activated by a positive slip control signal for blocking the first threshold device from generating the deceleration and acceleration signals and which blocking can be eliminated by the presence of a negative slip control signal.

Growing community of inventors

Seelze, Germany

Konrad Rode