Patent ID: 6913451

Claim:
In a vane pump operable for generating a vacuum and including a rotor mounted for rotation within a housing to define an eccentric chamber between a peripheral edge of the rotor and an inner wall surface of the housing, the rotor including a plurality of slots extending inwardly from the peripheral edge and the vane pump further including a plurality of elongated vanes each disposed in a respective one of the slots for outward sliding movement of the vanes in and along the slots from a nonoperating position in which an outer end of each vane is disposed in spaced relation to the housing inner wall surface and an operating position in which the outer end of each vane is disposed in contact with the inner wall surface by centrifugal force acting on the vanes as the rotor is rotated within the housing during vacuum-generating operation of the vane pump, the improvement comprising: a first stop on each of the slots; and a second stop located on each of the vanes for releasable engagement with the first stop of the respective slot to capture through said releasable engagement at least a longitudinal inner portion of each vane within the respective slot, said first and second stops being positioned on the slots and vanes so that, as frictional contact of the each vane outer end with the housing inner wall surface as the vane pump is operated causes gradual wear-based erosion of the each vane outer end to thereby longitudinally shorten the each vane and require added centrifugal force-induced outward sliding movement of the each vane from the first to the second position for attaining contact of the each vane outer end with the housing inner wall surface, the engagement of the first and second stops prevents continued outward sliding movement of the each vane beyond a predetermined point to maintain the at least a longitudinal inner portion of the each vane within the respective slot, wherein each said vane comprises a tapered sidewall that defines said second stop.