Vehicle braking systems

Claim 1

An anti-skid regulating system for pressuremedium-operated vehicle brakes, in which each wheel of an axle has an associated sensor for providing a signal characterising the rotational behaviour of that wheel, and the signals from the 4 GB 2 026 113 A 4 sensors are fed to an evaluation circuit which, on the basis of these signals, produces brake pressure control signals which are fed to brake pressure control devices for separately influencing the brake pressure atthe two wheels, the evaluation circuit including control means which, upon a reduction of pressure at one wheel, prevents a substantial buildup of pressure at the other wheel and, upon a pulsed or step-wise increase in pressure thereafter at one wheel, also only permits a synchronous pulsed or stepwise increase of pressure at the other wheel, and a junction from which branch lines leading from a source of brake pressure to the two wheel brakes is disposed in the immediate vicinity of the brake pressure control devices or in the brake pressure control devices themselves. 2. An anti-skid regulating system as claimed in claim 1, in which the flow resistance of a common line from the pressure source to the junction is at least as great as the flow resistance between the junction and a wheel brake, and in which a predetermined flow resistance can be obtained by throttling. 3. An anti-skid regulating system as claimed in claim 1 or 2, in which an inlet valve and an outlet valve are provided as the brake pressure control device for each wheel brake. 4. An anti-skid regulating system as claimed in claim 1 or 2, in which there is incorporated in a common brake line upstream of the junction from which the branch lines lead to the two wheel brakes, a valve which, when in one position, connects the source of brake pressure to the wheel brakes and, when in its second position, interrupts this connection and establishes communication between the wheel brakes and a return or relief line, and in which there is incorporated in each of the two branch lines leading from the junction to the wheel brakes a two port, two way valve which keeps the line open when in one position and closes the line when in the other position. 5. An anti-skid regulating system as claimed in claim 3 or4, in which the valves are integrated into a unitary valve arrangement. 6. An anti-skid regulating system as claimed in any of claims 1 to 5, in which the control means is adapted to operate such that, during a pressure drop atone wheel brake (without a regulating signal derived from the outer wheel), the pressure atthe other wheel brake is maintained constant. 7. An anti-skid regulating system as claimed in claim 6, in which the control means is further adapted to operate such that, when the pressure is being maintained at one wheel brake, it also main tains the pressure at the other wheel brake (without regulating signal) constant. 8. An anti-skid regulating system as claimed in claim 6, in which the control means is further adapted to operate such that, whilst the brake pressure is being maintained constant at one wheel brake following a pressure drop, it increases the pressure at the other wheel brake (without regulating signal) for a short time and otherwise also maintains it constant. 9. Anti-skid regulating systems for vehicle brakes, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Figures la and 1b of Figures 2 and lb, or Figures 3 and 1b of the accompanying drawings. 10. Anti-skid regulating system as claimed in claim 9, including control means constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Figures 4a and 4b, or Figure 5a and Figure 5b or Figure 5c or Figure 5d or Figure 5a of the accompanying drawings. 11. Anti-skid regulating systems as claimed in claim 9 or 10 adapted to operate substantially as hereinbefore particularly described with reference to Figure 6 of the accompanying drawings. ilrinteci tor Her Majesty's titationery Office by Croydon Printing Company Limited, Croydon Surrey, 1980. Published by the Patent Office,25 Southampton Buildings, London.WC2A lAY, from which copies may be obtained. 1. t