| 摘要 |
1456345 Anti-skid braking systems SOC ANON DBA 5 Feb 1975 [22 Feb 1974] 4945/75 Heading F2F An anti-skid braking system includes a circuit (Fig. 1) comprising a differential amplifier 28 with a first input 1 connected to a source of a voltage V representing the peripheral speed of a wheel, a second input 2 connected to a source 38/42 of a voltage U tending to increase linearly with time and a diode 40 or other unidirectional device with a threshold voltage u between the inputs 2 and 1, the amplifier 28 producing an output (V) connected to the input 2 and the circuit producing an output control signal A when the speed input signal V increases at a greater rate than the signal U. As shown the signal A is provided from an NPN transistor 32 and a PNP transistor 34 and the signal U from a constant current charging circuit 42 and a capacitor 38. Normally the voltages U and V differ by the threshold u (Fig. 2) but when the voltage V increases faster than the charging rate of the capacitor 38 as the unbraked wheel accelerates, t 1 -t 2 , the differential amplifier 28 is triggered to produce a straight edged signal T at t 2 to re-activate the brake. At t 3 the signal T is cancelled as the output U again exceeds the voltage V as the wheel is slowed. The braking system in Fig. 3 further comprises a solenoid isolating valve 10 connected by a diode D1 to the circuit, a logic control element 12 responsive to a particular value of speed decrease connected to a solenoid relief valve 14 and via a monostable 16 to the isolating valve 10, the monostable also being connected to the relief valve 14 and responsive to the output A of the above circuit. In use (Fig. 4) a signal C from the logic control element 12 actuates the isolating and relief valves 10 and 14 (D and I in Fig. 4), the monostable 16 continues their actuation until time tc when the brake relief ceases but the signal T from the above circuit maintains the isolating valve operative until time td. |
