| 摘要 |
1,169,081. Reciprocating pumps. E. D. LONG. Jan.24, 1967 [March 9, 1966], No.3541/67. Heading FIA. [Also in Division H2] In an electromagnetically-actuated pump comprising a bucket piston 11 of magnetic material, a cylinder 9 of non-magnetic material and a solenoid 13, the actuation of the solenoid is controlled by a switch 22 in the solenoid circuit. The reed switch 22 is mounted adjacent the outlet end of the cylinder 9 in the plane of the poles of permanent bar magnets 26 and 27. With the piston 11 abutting elastic stops 24, 25 it provides a path of low reluctance for the field of the magnets 26, 27 and the switch 22 is open. The switch is closed when the piston is drawn into the cylinder 9 by the solenoid 13. Power for the solenoid is provided by a direct current source (18, Fig. 3, not shown), through a transistor (19) and the switch 22 is connected between the base and emitter of the transistor. The switch 22 is opened and the transistor rendered non-conductive when the piston 11 has performed its suction stroke against the bias of spring 17. The spring 17 has a force displacement characteristic which approximates to the characteristic of the solenoid 13. The spring may be of volute or truncated conical contour or it may be of gradually increasing pitch. The pump cylinder 9 may be of brass or be formed as an integral part of the potting compound, e. g. epoxy resin, enclosing the components of the solenoid circuit. |
