Mercedes-benz Aktiengesellschaft

Daimler-benz Ag

Gerd Eilert

Manfred H Burckhardt

Richard Zimmer

Rainer Freitag

Reinhold Schoeb

Armin Mueller

Sinan Kazan

Rainer Spiecker

Karl-Heinz Richter

Helmut Struck

Volker Maass

Reinhold Schob

Bernd Scharnowski

Gerhard Rollmann

For the determination of the friction/slip characteristics of the tires of a road vehicle which is equipped with an antilock system designed for an individual wheel control, in an initial phase of a controlled braking, only the wheel brake of an individual vehicle wheel is acted upon by brake pressure and the latter is dimensioned so that the result is the initial retardation in accordance with the driver's wish. During this initial test phase of the braking, the absolute brake slip .lambda..sub.B as well as the friction utilization .mu..sub.B linked therewith is continuously determined as soon as, as a result of just the braking of the test wheel, the vehicle retardation z increases no further and/or the braked vehicle wheel is more strongly retarded than corresponds to a predetermined threshold value, the test braking is interrupted and the braking is continued by pressure action on the further vehicle wheels; corresponding test braking phases are carried out in cyclic sequence for all guidance wheels.

Process and system for determination of friction/slip characteristics of

Process for determination of friction/slip characteristics of the tires

An improved method is used to determine speed variation between wheels of different axles of a vehicle. The difference between the speeds of the rear wheels and the speeds of the front wheels is formed, and a correction is determined which compensates for the variations between the speeds of the front wheels and the rear wheels arising because of the vehicle geometry. The speed variation between the wheels of different axles of a vehicle is given by the difference plus the correction and, under particular driving conditions, which are characterized at least in that the acceleration of the rear wheels is below a threshold value at which there is no speed difference between the wheels of different axles because of drive slip, an adaptation of the correction takes place by determining the difference between the speeds of the rear wheels and the front wheels and by adapting the correction in such a way that the correction, under the particular driving conditions, is equal with respect to magnitude to the difference between the speeds of the rear wheels and the front wheels and exhibits a change of sign relative to this difference. In addition, or alternatively, in determining the correction, the vehicle transverse acceleration is taken into account by the magnitude of the correction becoming smaller with increasing transverse acceleration.

Method for determining the speed variation between wheels of different

A motor vehicle with four driving wheels and driven differential gearing for the drive, where (in the case of rotational-speed differences occurring between the wheels) a control device intervenes to distribute the drive power of an engine to the permanently driven wheels and/or the other driven wheels. This intervention occurs for a particular holding time which is progressively extended if a new intervention by the control becomes necessary after a test disconnection of the respective intervention. In addition, or alternatively, the control device can respond more sensitively and thus more quickly to rotational-speed differences of the wheels which may later occur during, or after, a test disconnection.

Motor vehicle with wheels driven via differential gearing or the like

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Schwaikheim, Germany

Gerd Eilert