GB577016A - Improvements relating to governors for controlling fluid-operated mechanisms - Google Patents

Abstract

577,016. Variable output pumps. LUCAS, Ltd., J., IFIELD, R. J., and NICOLLS, W. E. W. Sept. 16, 1941, Nos. 11847, 12755,14628 and 15648. [Class 135] A variable output pump of the swash plate type has the swash plate adjusted by a spring-loaded piston 3 housed in a cylinder 2, one end of which is connected directly to the pump de livery while the two ends of the cylinder are connected by a passage provided with an adjustable restriction. Discharge of fluid from the outer cylinder chamber to the main pump suction is controlled by a spring-loaded hinged leak-off valve 10. This valve is opened by a pressure from a centrifugal pump formed by passages x, y in the main rotor o transmitted through a passage 18 to act on the outer surface of a diaphragm 14. The diaphragm is adjustably loaded by a tension spring 20 regulated by a lever 22. When the pressure on the diaphragm exceeds a predetermined value pressure is vented from the outer cylinder space allowing the pressure on the other side to move the swash-plate to a position giving a smaller delivery. The main pump comprises a rotor having a series of spring-loaded plungers r engaging the swash plate and reciprocable in inclined bores t. The end face u of the rotor is provided with suitable ports for establishing communication with the inlet v and outlet w. In a modification the loading spring 20 is so mounted that it can be rotated by a hand lever from a position at right angles to the diaphragm to a position parallel to the diaphragm to vary the load on the diaphragm. In the latter position an abutment on the lever positively depresses the diaphragm to open the leak-off valve. To enable the pump to operate as a constant delivery pump the adjustable restriction is replaced by a spring-loaded piston valve 100 (Fig. 4). This valve is loosely fitted in the bore 102 to give a restricted passage between the two ends of the cylinder. The end of the valve is subject to the pressure in the main pump delivery and when this pressure exceeds a predetermined amount the valve is moved to establish a direct connection between the pump delivery and a passage 103 leading to the inner cylinder chamber. In a modification of this form the valve connects this chamber to a region of low pressure when the pressure, connection is interrupted. A second vent from the outer cylinder chamber may be fitted and controlled by a solenoid-actuated valve included in circuit with a thermally actuated switch or a thermo-couple and relay. The solenoid may be arranged as an over-riding control on the valve 10. The first Provisional Specification describes a fuel pump with plungers reciprocatory in a fixed casing, the plungers being rotated relatively to spill ports to vary the output. The control bar turning the pistons is actuated by a piston working in a cylinder having a restricted pressure inlet and a leak-off port controlled by a spring-loaded piston valve actuated by a centrifugal governor. The control valve may work in an adjustable sleeve In another arrangement the fuel supply is regulated by a spring-loaded piston under the control of a governing device. This comprises a chamber divided into two compartments by a diaphragm which serves to control a small vent aperture. Two pumps, one of which delivers a pressure proportional to its speed, delivers pressure to one chamber and may supply fuel oil to the injection pump or lubricating oil to the engine while the other pump supplies fluid to the other chamber and the power cylinder. The pipe connection to the power cylinder is fitted with a restriction and a branch pipe leads to the diaphragm chamber fitted with the leak-off valve. In a modification the first pump is replaced by a centrifugal pump whose sole function is to exert fluid pressure on one side of the diaphragm. In still another form the vent is controlled by a member connected through a lever with a barometric capsule subject to atmospheric pressure or the pressure in the engine induction pipe. The lever may have a variable fulcrum under the control of the pilot.