Patent GB-1431311-A (GB)
Title: Vehicle skid control system
IPC: G11C11/14
Filed: 1973-06-22
Abstract: 1431311 Anti-skid braking systems TEXAS INSTRUMENTS Inc 22 June 1973 [27 June 1972 3 July 1972 (2) 17 July 1972 27 July 1972 5 Sept 1972 2 Jan 1973 (2)] 29742/73 Heading F2F An anti-skid vehicle braking system includes a wheel speed signal generator 10, a vehicle speed signal generator connected to the output of the wheel speed signal generator, a comparator for comparing the wheel speed and vehicle speed signals and generating a first signal when their relationship is in a predetermined condition, a signal detector connected to the output of the wheel speed signal generator for generating a second signal when wheel speed rate of change has a first value and a third signal when the rate of change has a second value, signal generating means connected to the detector for producing a fourth signal proportional to selected conditions of vehicle speed after the first and second values are reached, and brake control mechanism including logic circuitry responsive to said first, second, third and fourth signals for releasing the brakes when the said predetermined condition and first value are reached and sequentially applying and releasing the brakes when said predetermined condition and the said second value are reached. The predetermined condition is a difference in speed between wheel speed and vehicle speed and the first and second values are respectively rates of deceleration and acceleration of the vehicle wheels. The wheel sensor 10 generates A.C. signals having a frequency varying in accordance with wheel speed and a converter 12 produces therefrom a D.C. signal, having a voltage magnitude varying with wheel speed, which is supplied to a slip and ramp signal generator and comparator 14 and to a detector and zero velocity gate circuit 16, the ramp signal representing vehicle speed and the output of comparator 14 being fed to a brake control logic circuit 18. The circuit 16 generates the second and third signals and supplies them to deceleration and acceleration differentiator circuits 20, 22 respectively, and supplies a signal to the logic circuit 18 when the D.C. speed signal reaches a predetermined level. Threshold gate circuits 24, 26 responding to signals from circuits 20, 22 supply signals to logic circuit 18. An acceleration programmer oscillator circuit 28 receives signals from circuits 20, 22 and produces a signal which is fed to a pulse generator circuit 32 which in response thereto provides a pulsed signal to the logic circuit 18. A reset and timer circuit 30 receives input signals from both circuit 18 and from threshold acceleration gate circuit 26 and commences a reset timing cycle at the end of the reset time period which develops a reset gate signal for selectively coupling the acceleration gate signal to logic circuit 18 which circuit develops output signals applied to a driver circuit 34 to "turn on" or "turn off" the brake control system. The A.C. wheel speed signal is also supplied to a failsafe monitoring circuit 36 wherein various module and other conditions are monitored for the purpose of providing an audible or visual indication of malfunction or blowing a fuse or actuating a circuit breaker or both. The monitoring circuit 36 includes an overcurrent detector 72, a power loss detector 74, an open circuit sensor detector 76, a solenoid fault detector 78 and a logic circuit 80.