Patent GB-1281296-A (GB)
Title: Fluid pressure-operated vehicle braking power regulation system
IPC: B60T8/1763
Filed: 1970-06-23
Abstract: 1281296 Anti-skid braking systems DAIMLER-BENZ AG 23 June 1970 [25 June 1969] 30485/70 Heading F2F A fluid pressure operated vehicle braking power regulation system includes an inlet and an outlet solenoid valve associated with each wheel brake, each brake being indirectly operated in response to electrical signals generated by a frequency generator associated with each wheel, the valves being actuated to regulate the fluid pressure at each brake in dependence on the magnitude of the electrical signals which are derived from a combination of a signal representing the speed of rotation of the wheel and a signal representing wheel slip obtained from the speed of rotation. As shown, the rotational speed information is obtained by frequency generators G 1 -G 4  and frequencyvoltage generators FSU 1 -FSU 4  so that a voltage proportional to the rotational speed is obtained and all voltages corresponding to that speed are brought together through diodes A 1 -A 4  at the point UM to form the maximum or reference voltage which is divided by resistors W 11  and W 12  in the ratio of the desired response rotational speed ratio of the vehicle axle 1 and the resultant voltage is passed for comparison purposes to a first input of the differential amplifiers DV 1  and DV 2 ; the partial voltage is similarly formed by resistors W 31 -W 32  for the vehicle axle 2 and transmitted to differential amplifiers DV 3  and DV 4  and the voltages corresponding to the rotational speed pass by way of diodes B 1 , B 4  and resistors W 13  to W 43  to the second input of the respective differential amplifier and a rotational speed comparison and a signal which corresponds to the slip of each wheel is obtained. The acceleration signal to be superimposed for a wheel is obtained from the rotational speed signal by differentiating the voltage corresponding to the rotational speed in differentiators D 1  to D 4  and the resulting acceleration signal is influenced by rotational speed evaluation so that an accelerationdependent voltage with rotational speed correction is available at the output of the differentiaters; by way of timing element Z11 and Z21 to Z41 and resistors W 14  and W 24  to W 44  this voltage is added at the second input of the amplifier DV 1  and DV 2  to DV 4  to the voltage obtained from the rotational speed of the respective wheel. By means of power transistors T 1  to T 4 , the output of each amplifier DV 1  to DV 4  controls the corresponding inlet solenoid valve V 1  to V 4  in the respective brake circuit the operation of which valves takes place when the voltage of the sum input is lower than the divided maximum voltage at the other input of the amplifiers. For the separate operation of the outlet-valves (not shown) the valve operating means are duplicated. The valves are actuated to give three conditions of operation in which the inlet valve is normally open and the outlet valve closed to obtain normal braking, both valvess are closed and fluid pressure at the brakes is retained, or the outlet valve opens to release the fluid pressure while the inlet valve remains closed.