Sump pump

Claim 1

A sealess sump pump having an electric motor and an impeller chamber spaced from the electric motor so that the impeller can be immersed in a liquid filled sump comprising: an electric motor having a motor shaft extending downwardly therefrom; a pump column extending downwardly from the motor; an impeller chamber mounted at the bottom of the pump column, said impeller chamber having an inlet port and an outlet port; an impeller journaled in the impeller chamber which when caused to rotate draws liquid into the inlet port and forces liquid out the outlet port; a driven magnet assembly fixed to rotate with the impeller; an elongate shaft extending downward from the motor shaft within the pump column, the length of said shaft and the driving magnet assembly being at least 8 inches; a driving magnet assembly mounted at the lower end of the elongate shaft; and a cylindrical nonmagnetic barrier between the driving and the driven magnet assemblies which seals the lower end of the pump column; said driving magnet assembly comprising a ferromagnetic ring with an even number of rare earth magnets equally spaced around the inner circumference of the ring, said magnets radially polarized and alternating in polarity; said driven magnet assembly having a ferromagnetic ring with a number of rare earth magnets equal to the number of magnets in the driving magnet assembly equally spaced around the outer circumference of the ring, said magnets being radially polarized and alternating in polarity.