Variable threshold electronic rate detection system for wheel skid control

Claim 2

An anti-skid brake control system for a vehicle comprising: a. means for generating a speed signal proportional to the rotational velocity of a wheel of said vehicle; b. differentiator means responsive to said speed signal for generating a deceleration signal; and c. wheel skid detector means for providing a wheel skid control signal to modulate brake force at a wheel whose generated deceleration signal exceeds a deceleration threshold, and for automatically adjusting said deceleration threshold from a first chosen value to a different value corresponding to the maximum value attained by said deceleration signal when said deceleration signal exceeds said first chosen threshold value such that a subsequent decrease of said deceleration signal below said different threshold value terminates said wheel skid control signal at a point in time prior to the time said deceleration signal decreases below said first chosen threshold value.

Claim 3

An anti-skid brake control system as recited in claim 1, further characterized in that the adjustment of said deceleration threshold to said different value is proportional to said deceleration signal.

Claim 4

An anti-skid brake control system as recited in claim 1, wherein said wheel skid detector means comprises: a. a constant voltage source; b. first circuit means including at least one diode to which a first voltage is connected from said voltage source at said first chosen threshold value; c. second circuit means having at least one other diode to which a second voltage is connected representative of said deceleration signal; d. a capacitor to which said diodes are connected in parallel for charging said capacitor to a potential corresponding to the higher of said first and second voltages to provide a reference signal; e. a comparator having a first inlet subject to said deceleration signal, a second inlet subject to said reference signal and an outlet providing said wheel skid control signal when said deceleration signal exceeds said reference signal; and f. a resistor in parallel with said capacitor for controlling the discharge of said capacitor so that said reference signal decreases at a slower rate than said deceleration signal.

Claim 5

An anti-skid brake control system as recited in claim 1, wherein said wheel skid detector means comprises: a. a constant voltage source; b. a transistor having an emitter terminal subject to said deceleration signal, a base terminal subject to a reference signal and a collector terminal at which said skid control signal is provided when said deceleration signal exceeds said reference signal; c. first circuit means including at least one diode to which a first voltage is connected from said voltage source at said first chosen threshold value; d. second circuit means including said emitter and base terminals of said transistor via which a second voltage representing said deceleration signal is conducted; e. a capacitor connected to the output terminal of said at least one diode and to said base terminal of said transistor so as to be charged according to the higher of said first and second voltages to provide said reference signal; and f. a resistor in parallel with said capacitor via which said capacitor is discharged at such rate that said reference signal decreases at a slower rate than said deceleration signal.