Patent GB-1422183-A (GB)
Title: Control of road vehicle braking presentation cap and container fitted therewith
IPC: G01S13/60
Filed: 1973-05-30
Abstract: 1422183 Automatic limitation of braking pressure FUJITSU Ltd and FUJITSU TEN Ltd 30 May 1973 [30 May 1972] 25867/73 Heading F2F [Also in Division H4] A road vehicle skid-control arrangement comprises two radars having respective transmitting/ receiving aerials 2, 3, Fig. 1, adapted to be mounted on the body of a vehicle 10 so as to be respectively directed forwardly and backwardly thereof, and obliquely downwardly by the same angle of declination # when the vehicle is at rest on a horizontal surface. Doppler signals are developed from the radars when the vehicle is in motion and are processed in associated circuitry to provide a control signal that gives a measure of the varying pitch angle a of the vehicle body when decelerating owing to applied braking. As described, the two aerials are connected to circuitry 22, Fig. 3, which comprises a Gunn diode acting as an oscillator and a mixer, and serving dual transmitting and receiving purposes. Respective Doppler signals appear on leads 221, 321, and are fed via amplifiers 23, 33 to limiters 24, 34, in which they are converted into square-wave signals of predetermined amplitude. The outputs from the limiters 24, 34 are applied to an arithmetic operation circuit 12, which extracts a pulse signal f(α), being the required control signal giving a measure of the pitch angle a, by comparison of the frequencies of the two square-wave signals. The pulse signal f(a) is then converted by a means 13 into an analogue signal, which is employed by actuating circuitry 14 to control a pressurereduction device 17 inserted in an hydraulic braking system 20 of the vehicle. The actuating circuit 14 comprises a differential amplifier 14b receiving one input from the converter 13 via an integration circuit 14a, which imposes a slight delay, and receiving another input from said converter directly. A command signal output is given when the delayed input signal exceeds the direct input signal in value, which indicates that the pitch angle has just passed its maximum value, and the device 17 is energized. As the pitch is subsequently reduced in consequence, the command signal ceases, whereupon the device 17 is de-energized, and so on (Fig. 4, not shown). In an alternative arrangement, the signal from the converter 13 is compared in value with a pre-set voltage from a potentiometer, representing a standard pitch angle, and a command signal is given when the actual pitch angle exceeds said standard pitch angle (Fig. 6, not shown). An AND gate 16 is provided which has one input connected to the circuit 14 and the other input connected to a detector switch 15 operated by the brake pedal 201. This ensures that any command signal from the circuit 14 is only passed to the device 17 when braking is actually taking place. The device 17, Fig. 5(a) comprises a valve 172 which, when operated by a solenoid 171 connected to the output of the gate 14, admits compressed air to a chamber bounded by two diaphragms 173, 174. The diaphragm 174 operates a valve 176, which shuts off the pipe from the master cylinder, and the diaphragm 173 withdraws a plunger 175, thereby increasing the volume of a chamber 177 from which the slave cylinders are supplied, and consequently reducing the braking pressure.