GB298612A - Hydro-pneumatic motor - Google Patents

Abstract

298,612. Compagnie Internationale des Freins Automatiques. Oct. 12, 1927, [Convention date]. Cam-actuated pumps; crank-actuated pumps; regulating delivery by opening suction valves; by stop valves.-In a hydro-pneumatic motor particularly for operating vehicle brakes, a pump forces liquid from a. discharge into a charge reservoir, the pump being rendered ineffective when the level or pressure in the charge or discharge reservoir reaches a predetermined value. As shown in Fig. 1, a pump 5 the delivery and suction strokes of which are respectively effected by a cam 11 on the vehicle axle and by a spring 5b is adapted to force liquid from a discharge reservoir 3 through passages 6, 7 into a closed charge reservoir 8. The suction valve 4a may be controlled by a magnet 4b in series with a switch controlled by manometer 8<c>, or by a float such as 8<b>, so that when the pressure or level of the liquid in the reservoir 8 reaches a predetermined value, the magnet is energized and holds the valve open. Alternatively, the supply to the pump may be controlled by a valve 3<d> operated by a diaphragm, as shown, or by a float in the reservoir 3. The valves 8<a>, 3<a> of the reservoirs 8, 3 are controlled by a switch 13 which has the following positions :-Releases position D ; tha magnets of both valves are energized, whereby the valve 3<a> is opened to permit liquid in the brake cylinder 26 to be returned by the spring 25<k> to the discharge reservoir 3; normal position M, in which both valves are closed; normal application position SS in which the valve 8a is deenergized and opens to supply the brake cylinder 26; emergency application position SU; in addition to the opening of the valve 8<a>, the valve 3<d> is held open. A passage 9 with a. small valve 3<h> enables the pressure, in the charge reservoir 8 to return to its normal valve after an emergency application. By opening a valve 10<a> the braking pressure may be established directly by the pump. To prevent the charge reservoir 8 from being completely emptied as by a number of consecutive applications of the brakes, the magnet of the release valve may, as shown, be connected in series with a switch controlled by a float 8<b> in the reservoir or by a manometer, so that it cannot be opened when the liquid is below a certain level. In another construction, the spring 5b is dispensed with and the return stroke of the pump is effected by the pressure of the liquid in the reservoir 3, the suction valve being spring loaded so that it ceases to open when the pressure is below a predetermined value. In a further construction, the pump is actuated by a crank and connecting-rod from the axle, through an electromagnetically actuated clutch controlled by a float in, or a manometer connected to, the reservoir 8, the clutch also being engaged for effecting an emergency application of the brake.