Protection of an all-wheel drive clutch of a motor vehicle with clutch-controlled all-wheel drive in a critical stall situation with clutch slip

摘要

One aspect of the invention is directed to methods for protecting an all-wheel clutch of a two-axle motor vehicle with clutch-controlled all-wheel drive. In the all-wheel drive, a primary axle is typically driven permanently and a secondary axle can optionally be driven by means of the controllable all-wheel clutch. According to the method, a critical braking situation with clutch slip in the all-wheel clutch is recognized for the all-wheel clutch. Both the accelerator pedal and the brake are actuated here. In addition, the vehicle is stationary or moves only slightly in the longitudinal direction of the vehicle. In the event of a critical braking situation with clutch slip, at least one of the wheels of the primary axle also spins (for example if the coefficient of friction of the primary axle is very low and the wheel braking torque is less than the drive torque) and clutch slip occurs on the all-wheel clutch. If a critical braking situation with clutch slip that is critical for the all-wheel clutch is recognized, a protective measure is taken against a thermal overload of the all-wheel clutch, for example the engine torque is limited or reduced so that the clutch slip and thus also the energy input into the all-wheel clutch are reduced.