GB1366843A - Electronic braking control system - Google Patents

Abstract

1366843 Anti-skid brake control systems SOC ANON DBA 23 Feb 1973 [15 March 1972] 9089/73 Heading F2F An electronic braking control system comprises means supplying a signal V, representing the speed of the wheel to be braked, to a logic circuit 26 which delivers to a brake pressure relaxation means a relax signal S whereby the trailing edge of the relax signal is delayed by an increasing signal V4 having exponential trend and a predetermined duration if the speed signal V and the exponential signal V4 intersect or when the duration expires. A speed sensor 22, e.g. electromagnetic, via a frequency/voltage converter 24, provides the speed signal V to a non-reactive passive dipole 42, e.g. a resistive voltage divider, to provide a signal V1 where where a = constant, positive and less than or equal to 1; b = constant and positive, or zero. The signal V1 passes to a reactive passive dipole 44, e.g. a capacitor/resistance combination to provide a signal V2 where where K, K<SP>1</SP>, K<SP>11</SP> are positive constants. The signal V2 is prevented from becoming less than V1 by one or more diodes. The speed signal V also passes to a dipole 46 similar to the dipole 42 supplying a signal V3 to one input of an exponential generator 48, its other input being a positive feedback of the relax signal S so that the exponential signal V4 is provided only during emission of the relax signal. A comparator 50 receives the phase shifted signal V2 and the exponential signal V4 and supplies a signal V5 representing the larger of the signals V2, V4 to a differential amplifier 52 which compares the signal V5 with the speed signal V and supplies the relax signal S when V5 is greater than V, to a solenoid valve 32 to close fluid communication to the wheel brakes 34. The exponential signal V4 provides an extension of the relax signal S for low wheel/road adhesion coefficient braking, the signal V4 being less than V2 when the coefficient is high, so that the exponential curve does not intersect the speed signal curve. The generator comprises a safety time delay circuit which cancels the output V4 after a predetermined time span from the initiation of the relax signal S, thus limiting the delaying effect of the exponential signal.