Improvements in or relating to electromagnetically actuated reciprocating pumps

摘要

1,040,281. Reciprocating pumps; hydraulic apparatus. FISHER GOVERNOR CO. Feb. 21, 1963 [May 14, 1962], No. 7041/63. Headings F1A and F1P. [Also in Division F2] A pump for actuating a control piston, e.g. for a valve (see Division F2), comprises a bucket 47 of magnetic material, e.g. a stainless steel, movable on its suction stroke by a solenoid 48 and on its delivery stroke by a spring 56. Solenoid 48 is supplied with alternating current, bucket 47 being drawn towards an axially adjustable core 58 of magnetic material at each half cycle. The pump is mounted in a reservoir 33 and draws through a bore in core 58. Delivery is effected via a check valve 52, a bypass valve 44 being held closed against a spring by a solenoid 59 during operation of the pump. A pressure relief valve 63 is provided in the delivery line. Fluctuations in delivery pressure are damped by a diaphragm loaded by air pressure. The bucket 47 is longitudinally grooved externally. The pump is rubber mounted to damp vibrations. In the embodiment shown, pumps 32 and 36 move a control piston 29 downwardly and upwardly, respectively, to operate a valve assembly 93, limit switches 70 and 75, respectively, being tripped at the end of each piston movement by a flange 79 on piston rod 78 to de-energise the pumps. A by-pass valve 44, 441 on each pump is held closed by a solenoid 59, 591 to lock piston 29 in position when the pumps are de-energised. A pressure-relief valve 64, 641 is provided in each pump delivery line. Indicator lamps 88, 881 are operated at the end of each piston movement. The position of the piston is also indicated by a washer 98 on the piston rod which is surrounded by a transparent housing. In the embodiment of Fig. 8, (not shown) pump 238 acts to move piston or diaphragm 235 upwardly against a spring 237. Alternatively, the pump may move the piston downwardly against a spring. Towards the end of the upward stoke the rise in pressure in pump delivery conduit 241 actuates a Bourdon tubeoperated switch 266 to de-energize the pump and light an indicator lamp 281, solenoid 261 controlling by-pass valve 263 remaining energized to lock piston 235 in position. On opening a switch 274, solenoid 261 is de-energized to permit the downward stroke of piston 235 by spring 237.