Patent ID: 6454548
Filing Date: 2002-09-24
Classification: A61M,F04B,Y10T

Abstract:
An electromagnetic pump comprising:a) a housing having an interior fluid containing region including a fluid receiving chamber and a fluid output chamber in fluid communication therewith, an inlet in fluid communication with said receiving chamber and an outlet in fluid communication with said output chamber; b) check valve means operatively associated with said fluid containing region for allowing fluid flow in a direction from said inlet through said outlet and blocking fluid flow in a direction from said outlet through said inlet; c) electromagnet means carried by said housing and located external to said fluid containing region; d) an armature positioned in said fluid containing region of said housing having a pole portion located for magnetic attraction by said electromagnet means and having a plunger portion rigidly extending from said pole portion, said plunger portion having one end adjacent said pole portion and an opposite end and having a constant cross-sectional dimension between said ends, said armature being movably supported in said housing for movement from a rest position through a forward pumping stroke when attracted by said electromagnet means to force fluid from said output chamber through said outlet and for movement in an opposite direction through a return stroke back to said rest position, said armature pole portion having a cross-sectional dimension measured in a direction substantially perpendicular to the direction of movement of said armature at least two times greater than a cross-sectional dimension of said armature plunger portion, there being a clearance of relatively small width between said armature plunger portion and said housing extending along the entire length of the constant cross-sectional dimension of said armature plunger portion between both of said ends, the width and length of said clearance and the length of the constant cross-sectional dimension of said plunger portion between said ends being selected to provide the sole means for guiding movement of said armature in said housing and the length of the constant cross-sectional dimension of said plunger portion between said ends being selected to restrict the amount of fluid leakage through said clearance thereby relaxing requirements imposed on the width of said clearance; e) means defining a magnetic circuit including said electromagnet means and said armature and a gap between said pole portion of said armature and said electromagnet means for moving said armature toward said electromagnet means to close said gap in response to electrical energization of said electromagnet means; and f) controlled means for providing a path in said housing for fluid around said armature plunger portion from said fluid receiving chamber to said fluid output chamber only during said return stroke of said armature.