Abstract: An electromagnetic pump of the built-in electromagnetic valve type including an electromagnetic plunger actuating electromagnetic coil and an electromagnetic valve operating electromagnetic coil disposed co-axially in adjacent relationship and having magnetic paths of their own separated from each other by a non-magnetic portion, to obtain a desired magnetic flux distribution. The two electromagnetic coils have the same direction of windings to obtain an improved magnetic flux distribution, thereby providing improved pump operation. By passing a half-wave rectified current or a pulse current of a predetermined cycle to the two electromagnetic coils connected in series with each other, a magnetic flux can be produced in each electromagnetic coil and made to flow in the magnetic path exclusive to each electromagnetic coil, so that mutual interference of the magnetic fluxes produced by the two electromagnetic coils can be avoided.

Abstract: An electromagnetic plunger pump includes a plunger which is electromagnetically activated. Normally, the plunger is supported in a balanced condition by a pair of opposing springs. Further, the plunger is vertically pierced by a hole extending along an axial line in which the plunger reciprocates in the vertical direction, responsive to an application of an intermittent electromagnetic force. A valve body is loosely fitted into a rod inserted in the vertical hole, reaching a contact portion of a discharge plunger, which interlocks with the electromagnetic plunger. The discharge plunger is forced shut by a spring acting in the valve closing direction. The valve body engages a valve seat to close a discharge passage during a pump shut-down. The valve body is liberated from the valve seat to open the discharge passage during pump operation.

Abstract: An electromagnetic pump characterized in that two independent coils disposed adjacent each other and via a common magnetic path are used for actuating a plunger and a valve, respectively, thereby preventing the generation of noises and abrasion during the operation of the pump. This also attains the quick return of the valve to its home position at the time when the pump stops, thus resulting in the complete stoppage of oil leak.

Abstract: An electromagnetic plunger pump capable of keeping its delivery pressure substantially constant when the value of a voltage applied thereto remains in the range of values within the tolerance limits of variations. In this pump, spring constants of a restoring spring and an auxiliary spring are selected and the positions of an electromagnetic coil, an electromagnetic plunger and an annular magnetic pole are fixed such that there exists a relationship 0.1<la/lb<1 between the distance lb between the magnetically neutral point of the electromagnetic coil and the magnetically neutral point of the electromagnetic plunger and the distance la between the upper end of the annular magnetic pole arranged below one end of the electromagnetic plunger and the lower end of the electromagnetic plunger. By this arrangement, it is possible to maintain the delivery pressure of the electromagnetic plunger pump in a stable range in spite of a variation in the value of the voltage applied thereto.

Abstract: An electromagnetic pump of the reciprocating type comprising a relief valve mechanism adapted to minimize the magnitude of pulsations of the fluid delivered by the pump and at the same time to act as a pressure accumulator. The relief valve mechanism comprises a pressure adjusting cylinder maintained in communication with the outlet side of the pump, a spring-loaded balancing plunger slidably mounted in the pressure adjusting cylinder, and a pressure adjusting screw adjustably mounted in the mechanism for regulating the biasing force of the spring so as to adjust the pressure applied by the spring to the balancing plunger to any level as desired.

Abstract: An electromagnetic pump comprising an electromagnetic coil, magnetic paths constituting a yoke arranged in the electromagnetic coil, an electromagnetic plunger reciprocatorily mounted in the electromagnetic coil, and a main body including a suction port, a discharge port and suction and discharge valve means and connected to the electromagnetic coil. At least one of the magnetic paths has a reduced cross-sectional area portion at one end portion thereof disposed on the longitudinal axis of the electromagnetic coil and is formed with a magnetic gap between the reduced cross-sectional area portion and the end portion of the electromagnetic plunger. A movable iron member of the cylindrical shape is arranged in the magnetic gap in which the lines of magnetic force are concentrated in passing through the magnetic path. The movable iron member is moved upwardly by the electromagnetic force to facilitate further concentration of the lines of magnetic force therein.