Patent ID: RE44841

Claim:
A pump comprising: a housing formed of a resilient material , a rotor path defined within the housing, an a first inlet formed in the housing at a first position on said rotor path, an a first outlet formed in the housing at a second position on said rotor path spaced from said first position, a rotor rotatable in said housing around an axis, the rotor having an outer rotor surface which seals against contacts said rotor path and resiliently distends said rotor path housing to provide a fluid-tight seal between the rotor and the rotor path , and at least one first chamber-forming concavity inwardly formed from said outer rotor surface, said first concavity a) having a first concave surface which is concave in planes including the rotor axis, b) being surrounded by said outer rotor surface, and c) solely forming a first conveying chamber travelling around said rotor path on rotation of the rotor to convey fluid around the housing; and a first resilient seal carried by the housing, located on said rotor path and extending between the first outlet and the first inlet in the direction of rotation of said rotor, said first resilient seal being adapted to seal with and be resiliently deformed by said outer rotor surface surrounding said first concavity to prevent fluid flow from said first outlet to said first inlet past the first seal, and to seal with said first concave surface of said first concavity, as said first concavity passes between the first outlet and the first inlet to squeeze fluid from the first chamber into the first outlet , and wherein the housing includes a second inlet and a second outlet spaced axially along the rotor from the first inlet and the first outlet, wherein the rotor includes at least one second chamber-forming concavity forming, with the housing, a second conveying chamber travelling around the housing between the second inlet and the second outlet to convey fluid from said second inlet to said second outlet, wherein the housing between the second outlet and the second inlet in the direction of rotation of the rotor includes a second resilient seal adapted to seal with and be resiliently deformed by the outer rotor surface of said second concavity to prevent fluid flow from said second outlet to said second inlet past said second seal, and to seal with a second concave surface of said second concavity, as said second concavity passes between the second outlet and the second inlet to squeeze fluid from the second chamber into the second outlet, wherein the rotor is movable axially between a) the above described position which aligns the first concavity with the first inlet and the first outlet and the second concavity with the second inlet and second outlet, and b) an alternative position of which aligns the second concavity with the first inlet and the first outlet while closing the second inlet and the second outlet .