Patent ID: 7625187

Claim:
A submersible pump, comprising: a pump body forming a main compartment having liquid intake and discharge openings, said pump body being adapted for submersion in a body of liquid whose level is to be controlled, a drive motor in said main compartment, an impeller coupled to the lower end of said drive motor for ejecting liquid through said discharge opening when said impeller is rotated by said drive motor, a sealed liquid-tight auxiliary compartment formed as an integral part of said pump body and located to be at least partially submerged in said liquid body, at least one electric-field sensor mounted on a circuit board, said circuit board being enclosed entirely within said sealed auxiliary compartment and attached to an inner surface of an outer wall of said sealed auxiliary compartment for producing an electric field that extends through said outer wall into the space adjacent the outer surface of said outer wall for detecting changes in the electric field of said sensor caused by a change in the elevation of the surface of said liquid body adjacent a portion of the outer surface of said sealed auxiliary compartment directly adjacent said sensor, a pair of electrical conductors for coupling said electric-field sensor and said drive motor to a power supply, a controllable switch coupled to at least one of said pair of electrical conductors for controlling the supply of electrical power to said drive motor, said electric-field sensor being connected to said controllable switch for turning said drive motor on and off in response to changes in the detected elevation of the surface of said liquid body adjacent the outer surface of said sealed auxiliary compartment, a detachable volute at the lower end of said main compartment to facilitate access to said impeller, and mechanical connectors formed as integral parts of said pump body and said volute for detachably attaching said volute to said pump body, said connectors including cam surfaces for drawing said volute tightly against said pump body as said volute is attached to said pump body.