Patent ID: 7125218

Claim:
A circumferential flow pump for fuel supply, comprising: a pump cover and a pump base that form a pump room; and a disc-shaped impeller designed to rotate in the pump room, the impeller having an annular outer circumferential wall and a plurality of impeller grooves that are partitioned by radial partition walls and arranged in the circumferential direction along the outer circumferential wall and that penetrate through the impeller to form openings in first and second end surfaces of the impeller, wherein: the pump cover and the pump base are formed with annular first and second feed passages, respectively, that are symmetrical and are opposed to the impeller grooves; each of the impeller grooves has a first bow surface that extends from an inner circumferential line, in the first end surface, of the impeller groove so as to have a radius R 1 , a second bow surface that extends from an inner circumferential line, in the second surface, of the impeller groove so as to have a radius r 1 , and a projected partition wall having a connecting surface that connects the first and second bow surfaces, centers of the radii R 1 and r 1 being located on the first and second end surfaces, respectively, or on a pump cover side of the first end surface and a pump base side of the second end surface, respectively, the first and second bow surfaces being symmetrical, the projected partition wall and the outer circumferential wall forming a space that penetrates through the impeller to form the openings in the first and second end surfaces; the first feed passage is defined by a first semicircular wall surface that has a radius R 2 and forms, in a cover end surface of the pump cover, an inner circumferential line and an outer circumferential line that are opposed to the inner circumferential line and the outer circumferential line, in the first end surface, of each of the impeller grooves, respectively, and the second feed passage is defined by a second semicircular wall surface that has a radius r 2 and forms, in a base end surface of the pump base, an inner circumferential line and an outer circumferential line that are opposed to the inner circumferential line and the outer circumferential line in the second end surface, of each of the impeller grooves, respectively, the first and second semicircular wall surfaces being symmetrical; and the radius R 1 of the first bow surface is longer than the radius R 2 of the first semicircular wall surface and the radius r 1 of the second bow surface is longer than the radius r 2 of the second semicircular wall surface.