GB1420424A - High pressure fluid intensifier and method - Google Patents

Abstract

1420424 Reciprocating pumps FLOW RESEARCH Inc 4 Jan 1974 [12 Jan 1973 26 Dec 1973] 00443/74 Heading F1A A hydraulically-actuated high pressure pump e.g. for supplying water to a nozzle 22 for cutting drilling or cleaning, comprises a double-acting motor piston 42 connected to pump pistons 44, 46 and reciprocating in chambers 48, 50 connected alternately to a working liquid supply pump 14 and a drain 107 by a hydraulically-actuated spool valve 38 which, in an intermediate position while reversing, connects the supply pump 14 output through a throttled passage means 114 to a low pressure zone, so that the back pressure during reversal is the same as that during the working strokes, thereby alleviating pressure shocks in the apparatus. The throttled passage means is constituted by tapered or stepped edges on the spool valve lands, Figs. 7, 10 and 14 (not shown). The valve spool is biased into its central position by springs 80, 82, and is moved into its left and right hand operative positions by working pressure under the control of pilot valves 85, 86, spool valve-actuating chambers 104, 105 being connected to supply pump 14 via throttles 110, 112 and to pilot valves 85, 86, which act to connect chambers 104, 105 to drain. In operation, in the position shown, pilot valve 86 is held open to vent spool valve chamber 105 by the pressure in working chamber 50, and pilot valve 85 is held closed by its spring 96 until engaged by piston 42, whereupon valve 85 is opened, venting spool valve chamber 104, so that the spool valve is moved into its intermediate position by its spring-loading. Working chamber 50 then de-pressurizes, permitting valve 86 to close and spool valve chamber 105 to pressurize thereby moving the spool valve to the right for the return stroke. If the pump output line 20 fails, the working chamber pressure falls and the associated pilot valve closes, causing the spool valve to move to its intermediate position and stopping of the pump. In normal use, when the pump is stopped, the spool valve moves to its intermediate position, and operation of a starting valve 120 to vent one of the spool valve chambers 104 or 105 is necessary to start the pump. In Figs. 12 to 14 (not shown), a pilot valve controlling the reversing of the spool valve is controlled with a quick-throw action by cables with plungers engaged by the working piston at the end of each stroke, the spool valve having an intermediate position in which, in addition to connecting the pump 14 through throttled passage means to a low pressure zone, the working chamber 48 or 50 under pressure is connected through a throttled passage to drain to alleviate pressure shocks.