Patent ID: 7669577

Claim:
A method for assembling a gerotor, the method comprising: providing a pump housing including a channel extending at least substantially therethrough and a rotor positioning cavity extending from the channel, a pump shaft having a central pump shaft axis, an outer rotor, and an inner rotor having a central inner rotor axis; wherein the pump shaft includes at least one pump shaft notch and the inner rotor has at least one protrusion being generally complementary to the at least one pump shaft notch; inserting the pump shaft through the channel in the pump housing and at least partially through the rotor positioning cavity; sliding the inner rotor onto the pump shaft at an oblique angle such that the central inner rotor axis is at least partially angularly offset from the central pump shaft axis; rotating the inner rotor such that the central inner rotor axis is substantially aligned with the central pump shaft axis to engage the pump shaft with the inner rotor; wherein rotating the inner rotor further includes complementarily engaging a notch edge of the at least one pump shaft notch with a protrusion edge of the at least one protrusion such that the engagement substantially secures the pump shaft axially to the inner rotor with respect to the central axis; and positioning the outer rotor around the inner rotor to maintain the substantial alignment of the inner rotor with respect to at least one of the pump housing and the pump shaft.