Patent ID: 7014436

Claim:
A pump comprising: a casing having an inlet port on an inlet side of the pump and a discharge port on a discharge side of the pump; a driving rotor that is supported for rotation within the casing, the driving rotor having a plurality of teeth, each of the plurality of teeth having a leading convex surface and a trailing surface; and a driven rotor that is supported for rotation within the casing in the same direction as said driving rotor, the driven rotor having a plurality of teeth, each of the plurality of teeth having a leading surface and a trailing flat surface, wherein the driving rotor and the driven rotor are positioned in the casing such that, as the driving rotor and the driven rotor rotate, the teeth of the driving rotor and the teeth of the driven rotor are interfaced with one another to form a seal between the inlet side and the discharge side of the pump, the seal being formed only between the leading convex surfaces of the teeth of the driving rotor and the trailing flat surfaces of the teeth of the driven rotor.