Patent ID: 7048524

Claim:
A positive-displacement pump, in particular for use in machines for dispensing fluids, comprising a body having a cylindrical cavity, a rotor ( 30 ) mounted rotatably inside said cylindrical cavity ( 11 a ) and having a peripheral curved surface ( 31 ) for defining a centered coupling without interference into said cylindrical cavity, wherein peripheral notches ( 32 ) are provided on the cylindrical peripheral curved surface ( 31 ) of said rotor ( 30 ) to define a plurality of peripheral teeth ( 33 ), an idle sprocket ( 20 ) being rotatably mounted without interference with a centering body ( 18 ) and having a plurality of teeth ( 16 ) meshed with said plurality of peripheral teeth ( 33 ) of said rotor ( 30 ), wherein portions of an undercut wall ( 35 , 36 ) spaced from the cylindrical cavity and elongated in the direction of the axis of rotation of said rotor ( 30 ) are provided on the peripheral curved surface ( 31 ) of said rotor ( 30 ), and at least one depression ( 34 ) is provided on the outer face of each peripheral tooth ( 33 ) between two adjacent peripheral notches ( 32 ).