GB819258A - Improvements in or relating to vehicle brakes - Google Patents

Abstract

819,258. Fluid-pressure brakes. RECHERCHES ETUDES PRODUCTION R.E.P. Sept. 14, 1956 [Dec. 2, 1955], No. 28212/56. Class 103 (1). In a device for controlling the braking effect of wheels of vehicles, an acceleration-responsive device opens and closes an electric circuit for applying to an hydraulic apparatus inserted in the line from the master cylinder to the wheel brake cylinder a force in opposition to the action applied by the master cylinder to effect braking. In the embodiment illustrated, an hydraulic device, in the form of a cylinder 5, in which moves a piston 6 against the force of a return spring 7, is interposed between the master cylinder 1 and the conduit D1 leading to a wheel brake cylinder F1. Similar apparatus may be interposed in each of the lines D2, D3 and D4 leading to the brakes of the other three wheels, if desired. The cylinder 5 is provided with an internal cylinder 8 in which operates an extension 6a of the piston 6. A conduit 9 leads to the base of the cylinder 8 and connects it to a distributcr 10 which receives fluid at high pressure through an inlet conduit 11 from an independent source of supply having a return conduit 12 leading to a high-pressure system incorporating a reservoir. In operation, when the angular deceleration of the wheel, due to braking, reaches a predetermined value, an accelerometer 17 closes the electrical circuit of electromagnet 16 and opens valve 13 and closes valve 14 in distributer 10 and places conduit 9 under high pressure to push back piston 6. The pedaloperated master cylinder piston 3 is thus moved back to react against the pressure applied by the driver and warn him that the control device has operated to render the brakes inactive. A spring-loaded valve 18 is provided in the piston 6 to ensure that in the case of excess pressure due to overheating the fluid is enabled to pass through the piston 6 from the right-hand face towards the left-hand face. If the volume of the cylinder swept out by the complete travel of the piston 6 is not sufficient to ensure braking- which would occur if the air had not been completely purged from the system, or should there be a leakage of fluid in the brake-the stem of the valve 18 comes into abutment against the internal cylinder 8 to open a direct passage for the braking fluid delivered from the master cylinder 1 to the brake under the action of the master cylinder piston 3.