Patent GB-543149-A (GB)
Title: Brake control means for automotive vehicles
IPC: B60T13/66
Filed: 1940-08-09
Abstract: 543,149. Valves. BENDIX AVIATION CORPORATION. Aug. 9, 1940, No. 12793. Convention. date, Aug. 15, 1939. [Class 135] [Also in Groups XXXI, XXXIV and XXXVII] Means for keeping the brakes applied when the vehicle is braked except on a decline of more than a pre-determined degree are rendered inoperative when the engine throttle is opened. The invention is particularly suitable for use with a vehicle having a fluid flywheel or hydraulic clutch 10, a friction clutch 12 and a step-by-step change speed gear 32. In the construction shown applied to a vehicle having hydraulic brakes 64, 70, applied by a brake pedal 38 and a master cylinder 36, a non-return valve 76, Fig. 3, is inserted in the brake pipe 40, 42, is normally kept open by its spring 90, but is closed to keep the brakes applied by means of a solenoid 74 energized whenever a throttle-controlled switch 98 and a pendulumcontrolled switch 100 are both closed. The switch 100 is closed when the vehicle is stationary and also on the level, on any upward incline, or on a slight decline; it is opened when the vehicle decelerates at more than a pre-determined rate and also when the vehicle stands on a steep decline. Thus, when the vehicle has been brought to a standstill and the brakes have been applied they are kept on by the valve 76 preventing the vehicle from running back on an incline and also preventing the vehicle from "creeping" forwardly due to the action of the hydraulic clutch if any of the gears are left engaged. The inertia or gravity switch 100 may be of the pendulum type or an inertiaoperated mercury switch. The invention may be applied to a vacuum braking system, the usual 3-way brake valve and the valve 76 being inserted in the conduit connecting the intake manifold of the engine with the vacuum motor of the brake. Valves.-The non-return valve 76 comprises a body 78, a plunger 84 controlled by a spring 90 and having an extension 86 which normally keeps the ball 82 of its seat, and a solenoid 74 which when energized draws back the plunger and allows a spring 162 to press the ball on to its seat. Switches.-The switch 100, Fig. 6, comprises a pendulum 138 pivoted on a pin 136 and having an extension 158 adapted to engage a lug 146 on an arm 148 separately pivoted on the pin 136, the pendulum and arm being connected by a tension spring 150 attached thereto at 154, 152 respectively and passing on either side of the pivot pin 136 in the two limiting positions of the arm and pendulum. The arm 146 carries a contact 142 which in the position shown engages a fixed contact 140 so that the switch is closed. An adjustable stop 156 is provided on the rear side of the switch, so that if the vehicle is standing on an incline the pendulum bears against this stop. If the vehicle is standing on a decline of more than a predetermined degree, or if it is decelerated suddenly the pendulum moves to the right sufficiently for the spring 150 to pass to the right of the axis of pin 136 and cause the contacts 140, 142 to separate. Modifications are described in which the switch contacts are always biased to the closed position by a spring but are separated positively by the pendulum when the vehicle is on a decline or is strongly decelerated.