Electromagnetic pumps

Claim 2

In an electromagnetic pump comprising a cylinder, an inlet valve means positioned adjacent one end of said cylinder, an outlet valve means positioned adjacent the other end of said cylinder, a plunger contained in the cylinder to be moveable in the axial direction, an electromagnetic coil disposed about said cylinder, said coil constituting an oscillator assembly together with a transistor, and a housing member including a magnetic yoke member, whereby the plunger is reciprocated by pulsating current supplied to said electromagnetic coil, the improvement which comprises an insulating layer formed on the outer surface of said oscillator assembly, and a foamed member filled in a space within said housing member, said housing member surrounding said oscillator assembly, said layer and said foamed member so that said oscillator assembly is completely isolated from environmental contaminants.

Claim 3

The invention according to claim 1 wherein said oscillator assembly comprises a printed circuit board which supports said transistor and component elements of an oscillator.

Claim 4

The invention according to claim 2 wherein said transistor is molded in resin.

Claim 5

The invention according to claim 3 wherein said transistor is mounted on a cooling metal plate positioned coplanar with said printed circuit board in edge-to-edge relation.

Claim 6

The invention according to claim 4 wherein said metal plate is in contact with and supported by a metal portion of said housing member.

Claim 7

In an electromagnetic pump in which an inlet fixture and an outlet fixture are disposed on the opposite ends of a non-magnetic sleeve, a plunger is contained within said sleeve to be moveable in the axial direction, an exciting coil is wound about the sleeve between the inlet and the outlet fixtures, a transistor is combined with said exciting coil to constitute an oscillator assembly so as to excite the exciting coil by pulsating current thus reciprocating the plunger in the sleeve, and a suction valve and a discharge valve are arranged in series with the sleeve, the improvement which comprises a U shaped yoke member including a pair of spaced legs which respectively support said inlet and outlet fixtures, and a connecting plate for interconnecting one end of said legs, a housing member combined with said yoke member to close an opening thereof, an insulating layer applied to the outer surface of said oscillator assembly disposed between said pair of legs, and a foamed member disposed in a space defined by said yoke member and said housing member, said oscillator assembly being positioned within said space, whereby said oscillator assembly is comletely isolated from environmental contaminants.

Claim 8

In an electromagnetic pump in which an inlet fixture and an outlet fixture are disposed on the opposite ends of a non-magnetic sleeve, a plunger is contained within said sleeve to be moveable in the axial direction, an exciting coil is wound about the sleeve between the inlet and the outlet fixtures, a transistor is combined with said exciting coil to constitute an oscillator assembly so as to excite the exciting coil by pulsating current thus reciprocating the plunger in the sleeve, and a suction valve and a discharge valve are arranged in series with the sleeve, the improvement which comprises a U shaped yoke member including a pair of spaced legs which respectively support said inlet and outlet fixtures, and a connecting plate for interconnecting one end of said legs, a housing member combined with said yoke member to close an opening thereof, an insulating layer applied to the outer surface of said oscillator assembly disposed between said pair of legs, and a foamed member disposed in a space defined by said yoke member and said housing member, said oscillator assembly being positioned within said space, whereby said oscillator assembly is comletely isolated from environmental contaminants.

Claim 9

The electromagnetic pump according to claim 6 wherein said transistor is molded in resin.