Low power electromagnetic pump

Abstract

An electromagnetic pump comprising a housing having a fluid receiving chamber in communication with an inlet, a pair of serially-connected fluid pumping chambers, one in communication with the fluid receiving chamber and the other in communication with an outlet, an electromagnet carried by the housing located external to the fluid chambers thereof, and a barrier in the form of a thin diaphragm of fluid impermeable material which heremetically isolates the electromagnet from the fluid chambers. An armature in the housing is movable within a body of magnetically permeable material, has a pole portion located for magnetic attraction by the electromagnet, and has first and second plunger portions in respective ones of the pumping chambers for forcing fluid out of the chambers and through the outlet. The armature is moved from a rest position through a forward pumping stroke when attracted by the electromagnet to force fluid from one pumping chamber to the other and then out of that chamber through the outlet, and the armature is moved by a biasing spring in an opposite direction through a return stroke back to the rest position. A pump check valve is within the pump and associated with the armature in the form of a valve member located in the fluid receiving chamber, movably carried by the armature, and positioned for closing the pump inlet when the armature is in the rest position and opening the inlet after the armature begins the forward pumping stroke. The arrangement is such that the volume of the fluid receiving chamber is minimized in the region between the check valve and the neighboring one of the armature plunger portions. Long term sealing against back flow is provided by a relatively stronger biasing spring, and short term sealing by a relatively weaker biasing spring.