Abstract: A tooth profile of an inner rotor 2 is formed by an envelope of a group of circular arcs of a locus circle C having a center on a trochoidal curve TC. The envelope of the group of circular arcs is formed by rolling a rolling circle having a predetermined diameter along a base circle without slipping and drawing the trochoidal curve TC based on a point distant from the center of the rolling circle by a distance equivalent to an amount of eccentricity between the two rotors. A diameter d2 of the locus circle C is constant until one point between an addendum point and a dedendum point of the inner rotor and changes from the one point such that a diameter d2B at the dedendum point becomes larger than a diameter d2T at the addendum point of the inner rotor.

Abstract: A tooth profile of an inner rotor 2 is formed by an envelope of a group of circular arcs of a locus circle C having a center on a trochoidal curve TC. The envelope of the group of circular arcs is formed by rolling a rolling circle having a predetermined diameter along a base circle without slipping and drawing the trochoidal curve TC based on a point distant from the center of the rolling circle by a distance equivalent to an amount of eccentricity between the two rotors. A diameter d2 of the locus circle C is constant until one point between an addendum point and a dedendum point of the inner rotor and changes from the one point such that a diameter d2B at the dedendum point becomes larger than a diameter d2T at the addendum point of the inner rotor.

Abstract: An object is to meet the demands for increasing the number of teeth of a rotor in an internal gear pump while maintaining a theoretical discharge amount by using an equivalent body configuration so as to enhance the pump performance relating to discharge pulsation due to the increased number of teeth. In a pump rotor 1 formed by combining of an inner rotor (2) having N teeth and an outer rotor (3) having (N+1) teeth and disposing the rotors eccentrically relative to each other, the relational expression ?Dmax<1.7e·sin(?/180)/sin {?/(180·N)} is satisfied, ?Dmax being a maximum value of a working pitch diameter of the inner rotor (2) and the outer rotor (3), and a working position (G) of the inner rotor (2) and the outer rotor (3) is always located rearward of an eccentric axis (CL) in a rotating direction of the rotor.

Abstract: A gear pump rotor is provided including a combination of an inner rotor and an outer rotor whose numbers of teeth are different by one, and the discharge amount of the pump is increased by an increase of the tooth depth. At least one of an addendum curve and a dedendum curve of an inner rotor is formed by a locus of one point on formation circles that satisfy moving conditions that the formation circles move from moving start points to moving end points while changing the distances from an inner rotor center to the centers of the formation circles. The centers of the formation circles move by a distance in the radial direction of a base circle, and the formation circles rotate by an angle at a constant angular velocity in the same directions of the moving directions of the formation circles.

Abstract: An object is to meet the demands for increasing the number of teeth of a rotor in an internal gear pump while maintaining a theoretical discharge amount by using an equivalent body configuration so as to enhance the pump performance relating to discharge pulsation due to the increased number of teeth. In a pump rotor 1 formed by combining of an inner rotor (2) having N teeth and an outer rotor (3) having (N+1) teeth and disposing the rotors eccentrically relative to each other, the relational expression ?Dma <1.7e·sin(?/180)/sin {?/(180·N)} is satisfied, ?Dmax being a maximum value of a working pitch diameter of the inner rotor (2) and the outer rotor (3), and a working position (G) of the inner rotor (2) and the outer rotor (3) is always located rearward of an eccentric axis (CL) in a rotating direction of the rotor.

Abstract: Flexibility is given in setting the tooth depth and the number of teeth of a pump rotor including a combination of an inner rotor and an outer rotor whose numbers of teeth are different by one, and the discharge amount of the pump is increased by the increase of the tooth depth. At least one of an addendum curve and a dedendum curve of an inner rotor (2) is formed by a locus of one point (j) on formation circles (B, C) that satisfy moving conditions that the formation circles (B, C) move from moving start points (Spa, Spb) to moving end points (Lpa, Lpb) while changing the distances from an inner rotor center (OI) to the centers of the formation circles, the centers of the formation circles move by a distance (R) in the radial direction of a base circle (A) during this, and the formation circles (B, C) rotate by an angle ? at a constant angular velocity in the same directions of the moving directions of the formation circles.

Abstract: A noise-reduced internal gear pump incorporating an inner rotor having an addendum formed by a smooth curve and a dedendum formed by a hypocycloid. The tooth profile of the outer rotor is determined by the following steps. The center Oi of an inner rotor 1 is revolved around the center Oo of the outer rotor so as to form a circle S having a diameter of 2e+t, where “e” is the amount of eccentricity between the inner and outer rotors and “t” is the maximum value of the interrotor clearance between the outer rotor and the inner rotor pressed against it. The inner rotor 1 is rotated on its axis 1/n times while its center Oi makes one revolution in the circular orbit S, where “n” is the number of teeth of the inner rotor. The envelope of the group of the tooth profile-curves of the inner rotor formed by its revolution is used as the tooth profile of the outer rotor.

Abstract: A noise-reduced internal gear pump incorporating an inner rotor having an addendum formed by a smooth curve and a dedendum formed by a hypocycloid. The tooth profile of the outer rotor is determined by the following steps. The center Oi of an inner rotor 1 is revolved around the center Oo of the outer rotor so as to form a circle S having a diameter of 2e+t, where “e” is the amount of eccentricity between the inner and outer rotors and “t” is the maximum value of the interrotor clearance between the outer rotor and the inner rotor pressed against it. The inner rotor 1 is rotated on its axis 1/n times while its center Oi makes one revolution in the circular orbit S, where “n” is the number of teeth of the inner rotor. The envelope of the group of the tooth profile-curves of the inner rotor formed by its revolution is used as the tooth profile of the outer rotor.