Permanent magnet type pump

Claim 1

A light-weight permanent magnet type pump having a pump impeller shaft and a permanent magnet drive means therefor, said drive means comprising an interior rotor fixed to the pump impeller shaft, an exterior rotor mounted for rotation closely adjacent the interior rotor with an air gap therebetween, said interior rotor being adapted to receive a drive torque of at least 1 m· kg transmitted in synchronism by said exterior rotor, said pump impeller shaft and said interior rotor being housed and supported in a single sealed chamber, a partition of non-magnetizable material extending through said air gap and closing said chamber, a closed ring on each of the opposed surfaces of said interior and exterior rotors, each of said closed rings being formed by the same even number of permanent magnets of alternating polarity and embedded in a non-magnetizable material in side-by-side contiguous array, each of said magnets being a relatively thin magnetic plate formed of a magnetic material containing alloys of cobalt and rare earths and magnetized in the direction of the thickness of said air gap, said magnets each having a magnet length, extending in the direction of thickness of said air gap, which is somewhat larger than the air gap thickness, each of said magnets having a magnet width, extending in the direction of rotation, which is larger than said magnet length.