Propulsion control using longitudinal acceleration to determine slip thresholds

Claim 1

In a propulsion control system for preventing an undesirable spinning of the wheels of a vehicle that are to be controlled, particularly of a motor vehicle equipped with multi-axle drive, having a plurality of sensor means for providing speed signals indicative of the sensed speed of the associated wheels, having a threshold means for forming slip threshold value, having a slip comparator means assigned to each wheel to be controlled for comparing the sensed speed signal of the wheel to be controlled with the assigned slip threshold value, having means for activating the brake of a wheel to be controlled when said wheel tends to spin, having means for reducing the output torque of the vehicle engine when the wheels of both vehicle sides that are to be controlled tend to spin, and having measuring means for measuring the longitudinal acceleration of the vehicle, the improvement comprising: an integrator means for integrating the output signal of the measuring means for the longitudinal acceleration of the vehicle, a subtractor means for forming the difference of the output signals of the measuring means for the longitudinal acceleration of the vehicle and of the integrator means, an adder means for adding to the output signal of the subtractor a constant value assigned to a certain acceleration value, and said threshold means for forming the slip threshold value by assigning one of said speed signals of one of said plurality of sensor means as the driving speed and multiplying the assigned speed signal with a factor to produce the slip threshold value, said threshold means includes an integrating circuit for integrating the assigned speed signal with a time constant represented by the output signal of the adder means before multiplying.