GB530050A - Improvements in or relating to hydraulically actuated pumps - Google Patents

Abstract

530,050. Reciprocating pumps. STEVENS, A. H. (Jackson Co., B.). June 2, 1939. No. 16275. [Class 102 (i)] In a hydraulically operated piston-pump with surge means actuated only during reversal of the pump stroke, either the pump or the surge means or each comprises two cylinders with inter-connected pistons. A pump for liquid drilling-mud comprises a mud box 24 communicating, through inlet valves 28, cylinders 1, 2 containing inter-connected pistons 4, 6, outlet valves 28, and a surge regulator R, with a discharge opening 38. Motive fluid 51 is admitted alternately to the inner ends of the cylinders 1, 2 by ports 55, 57 and valves 42, 43 operated by pistons 44, 45 and fluid admitted by pilot valves 83, 84 which are operated by cams 73 on the pistons 4, 6, exhaust being effected by the same valves and ports 62, 91. The surge regulator comprises a freely movable piston 102 in a cylinder 101 connected at its lower end with the mud discharge ports 34 and at its upper end with the motive fluid supply 51. In a modification the mud valves, not shown, are arranged in the central casting 3 and are connected to the outer ends of the cylinders by annular ports 146, Fig. 5, and openings 147. The pilot valves 83, 84 are operated by levers on shafts 175 oscillated by levers thereon and the cams 73. The movement of the main pistons 4, 6 may be slowed down at the ends of the stroke by throttling the main valves 42, 43 or by providing dash pots 110, 111, Fig. 1. The surge regulator may comprise two pistons 183, 184, Fig. 6, connected by a tube 185 and adapted to move in cylinders 181, 182 the ports 201, 202, 194, 195 of which are connected respectively to the motive fluid supply, exhaust, the mud inlet and the mud outlet. This regulates the flow in all four passages. In order to equalize the flow more completely the surge pistons and their connecting rod are made of the same diameters as the main pistons and their rod 5 as shown in Fig. 29 and the port 202, instead of being permanently joined to exhaust, is connected to ports 287 controlled by pistons 281 of the main valves 42, 43 to admit low pressure fluid, which is also used to operate the pilot valve, so as to move the pistons towards position shown in Fig. 25 during the main part of each stroke of the main pistons 4, 6 and to allow this low pressure fluid to escape when the valves 42, 43 are moving from one end position to the other and the pistons 4, 6 are reversing. If the motive fluid is supplied by a multi-stage centrifugal pump the low pressure fluid may be bled from the first stage. Specification 530,058, [Group XXI], is referred to.