Patent ID: 8632323

Claim:
An internal gear pump rotor that comprises in combination an inner rotor having n-number of teeth and an outer rotor having (n+1)-number of teeth and that sucks and discharges fluid by a change of a capacity of a pump chamber provided between the teeth of the rotors owing to rotations of the rotors, wherein formation circles move in a manner such as to satisfy the following conditions, and at least one of an addendum curve and a dedendum curve of a tooth profile of the inner rotor is formed by a locus curve drawn, during the movement, by one point that coincides with an addendum bottom or a dedendum top and a reference point on a base circle A concentric with an inner rotor center and that is on the formation circles: While changing radial distances from the inner rotor center to centers of the formation circles by a distance, the centers of the formation circles move from moving start points where the centers are positioned when the formation circles are arranged so that the point coincides with the reference point on the base circle, to moving end points where the centers are positioned when the formation circles are arranged so that the point is positioned at an addendum top or a dedendum bottom, and the formation circles rotate through an angle of 180° at a constant angular velocity in the same direction as moving directions of the formation circles, wherein a radial distance between the moving start points and the moving end points is the distance, wherein the centers of the formation circles move from the moving start points to the moving end points while the formation circles reduce diameters thereof, and at least one of the addendum curve and the dedendum curve of the tooth profile of the inner rotor is formed by a locus curve drawn by a point on outer peripheries of the formation circles whose diameters change.