GB850547A - Fluid pressure control apparatus for regulating the speed of variable speed internal combustion engines - Google Patents

Abstract

850,547. Fluid-pressure servomotor-control systems. WESTINGHOUSE AIR BRAKE CO. Oct. 16, 1957 [Oct. 16, 1956], No. 32326/57. Class 135. Fluid-pressure apparatus regulating the fuel supply and speed of an I.C. engine comprises a double-acting actuator 7 responsive to differential pressure to vary the fuel supply or maintain a given supply when the pressures are equal, operator-controlled valve means 3 for selecting a pressure for a desired speed, engine-speed responsive valve means 4 controlling the opposing pressure in accordance with actual speed, and means 5, 6 responsive to reduction of one of the opposing pressures below a certain low valve to cause the actuator to shut off fuel supply. Initially compressed air at 2 passes open valve 61 to shift valve 67 to the left and, together with spring 13, moves diaphragm 7 and fuel supply control rod 12 downward to fuel off position. The air also passes open speed controlled valve 24 to load diaphragm 54 downwards with a pressure of 10 p.s.i. to close valve 61 and open vent valve 64 so that valve 67 moves to the right. At a pressure of 15 p.s.i. speed and manual-controlled valves 24 and release valves 28 are closed by their diaphragms 15 so that air at this pressure is trapped in both pairs of chambers 20, 22, pipes 23, 36 and the chambers 9, 10 on either side of diaphragm 7. To start the engine, handle 31 is moved to the left so that cam 32 loads spring 30 and opens valve 24 so that air passes to the chamber 9 and lifts diaphragm 7 and rod 12 to maximum fuel supply position. The handle 31 is then moved to set a pressure in chamber 9 corresponding to a required speed and the engine-driven centrifugal governor 38 produces a corresponding pressure in chamber 10 via its spring 30 and valve 24 to balance the pressure in chamber 9 and hold the rod 12 in a position to maintain the required speed. If the load increases, the speed decreases and governor 38 opens its release valve 28 to reduce pressure in chamber 10 to increase the fuel supply and maintain the speed set by handle 31. With decrease in load and increase in speed, the governor opens its valve 24 to increase pressure in chamber 10 to reduce fuel supply to keep the speed constant. Should governor valve 4 fail, e.g. by rupturing diaphragm 19, pressure falls in pipe 36 and diaphragm 54 rises to close valve 64 and open valve 61 so that pressure at 2 shifts valve 67 to the left and rod 12 to fuel off position. In an alternative embodiment, air from the manuallycontrolled valve loads a diaphragm which closes the speed-controlled air supply valve on a spring- loaded vent valve and the governor acts directly on the valves through a rod.