Anti-lock brake control system for motor vehicles

Claim 1

An anti-lock control system for motor vehicles wherein a respective wheel speed Vw of the motor vehicle is detected; a computed vehicle speed Vv approximate to the real vehicle speed is calculated on the basis of the detected wheel speeds; a reference wheel speed Vr is set up which follows said wheel speed Vw with a predetermined speed difference ΔV and decelerates from a point of time when the deceleration of the wheel speed Vw becomes equal to a predetermined value; and reduction of the brake hydraulic pressure is started at a point of time when the decelerating wheel speed Vw becomes equal to the reference wheel speed Vr, said anti-lock control system comprising: a first means for setting up first and second threshold values Vv1 and Vv2 which follow said computed vehicle speed Vv with predetermined speed differences ΔV1 and ΔV2, said first threshold value being higher than said second threshold value; a second means for measuring a time period T during which said wheel speed Vw which accelerates and decelerates in repetition reciprocates once between said first and second threshold values Vv1 and Vv2; and a third means for changing said reference wheel speed Vr to a second reference wheel speed Vr' on the basis of a predetermined speed difference ΔV' which is greater than said speed difference ΔV when it is detected that the time period T is shorter than said predetermined time period T1.