Sump pump

Claim 1

A sump pump constructed principally of molded plastic, comprising a hollow molded plastic base, forming a chamber, and having openings therein for the passage of water from the exterior into the chamber, said base having a water discharge opening therein, a pump structure disposed in said base chamber having a water inlet opening communicating with the chamber interior and a water discharge opening communicating with said discharge opening in the base, an electric motor including a drive shaft, a rotor mounted on said drive shaft, a cooperable stator core and a stator-energizing field winding, a molded plastic motor housing having a lower housing section and an upper housing section, said housing sections having adjacent mating edge portions connected in fluid-tight relation to form a closed housing, the opposite end of said lower section being mounted on said base with the bottom wall of said lower section extending across an opening in the adjacent wall of said base, said lower section being provided with means on which said stator core is seated in radially fixed relation and with the core axis disposed vertically, a bearing cap seated upon the upper end of said stator core in radially fixed relation, means operable to retain said lower section, stator core and bearing cap in axially fixed relation, said cap and the bottom wall of the lower housing section having respective aligned bearing means therein for aligning said drive shaft and rotor on the axis of said stator core, the upper bearing means carried by said cap permitting unrestricted axial movement of said shaft and the lower bearing means comprising an outer bearing race fixedly mounted on said bottom wall of the lower section, and a cooperable concentrically disposed inner bearing race fixedly mounted on said shaft with said races being operatively connected by a plurality of bearing elements operative to maintain said races in axially fixed relation, and thus support said drive shaft and rotor in operative axially fixed relation with respect to said stator core, the lower end of said drive shaft extending through said bottom wall into said chamber and through the inlet opening of said pump, an impeller mounted on the adjacent end of said shaft and rotatable therewith, seal means, disposed below said lower bearing, encircling the lower end of said shaft and comprising a stationary member carried by said bottom wall of the lower section and a cooperable member slidably and rotatably carried by said shaft and engageable with the stationary member to form a fluid seal, axially fixed means mounted on said shaft for restricting downward movement of said cooperable member thereon, and means cooperable with said restricting means and cooperable member for forming a fluid seal between the latter and said shaft, and or urging said stationary and cooperable members in operative engagement, forming a fluid seal between said shaft and said bottom wall, the latter having at least a portion thereof extending across said Base opening formed from a material having greater thermal conductivity than the plastic of said lower section, forming a heat sink operatively disposed between the interior of the motor housing and the base chamber, said bearing cap being provided with the openings therein, and said drive shaft being provided, adjacent the lower end of said rotor, with a plurality of impeller blades, and a supply of liquid coolant contained within said motor housing and adapted to circulate therein by means of said impeller blades, with said heat sink being operative to conduct heat from such liquid coolant to the water being pumped.