GB592618A - Improvements in means for regulating piston type variable delivery pumps - Google Patents

Abstract

592,618. Fluid-pressure servomotorcontrol systems. PRECISION DEVELOPMENTS CO., Ltd., ROSSZ, L., and OLAH, G. Feb. 15, 1944, No. 2816. [Class 135] In a variable delivery radial-cylinder reciprocating pump, the pistons are actuated by an eccentric 2, the throw of which is varied by pistons 8 and 12 that engage it. The piston 12 is forced out of its cylinder 13 by a spring 11 or fluid pressure or, as shown in Fig. 3, a combination of both, to maintain the stroke of the pistons at a maximum. A valve 14 is maintained against the stop 18a by a spring 15 and is acted upon by the pump delivery pressure in port 16, which is also transmitted through the port 17 to the piston 12. When the pump delivery pressure is below normal, the cylinder 9 is connected to the exhaust ports 20, through a passage 18, and around the reduced portion 14a of the valve. As the delivery pressure rises, the valve first closes the exhaust connection and then admits pressure fluid to the piston 8 to move the eccentric to reduce the pump stroke. If the delivery pressure still increases, the groove 14c in the-valve-moves to connect the pump delivery to exhaust; a further relief valve may also be fitted. Fig. 4 shows a modified valve in which initial movement first closes port 18 leading to the piston 8 and disconnects it from the exhaust port 20 and further, movement opens port 18 to receive pressure fluid from the port 16, until finally, the port 16 is connected to the exhaust 20. A throttle passage 23 may be fitted between the valve and exhaust or between the pump delivery and the piston 8. The loading of the valve 14 may be effected by two springs acting through a toggle.