Abstract: An inner motor is structured to increase the discharge rate of an internal gear pump by making it possible to freely adjust the eccentricity e between the inner and outer rotors. Each tooth of the inner rotor includes a tooth bottom defined by hypocycloidal curves, an engaging portion to be brought into engagement with the outer rotor and defined by involute curves, and a tooth top defined by a predetermined curve such as a part of a circle or an oval or an epicycloidal curve.

Abstract: It is aimed to increase the discharge rate of an internal gear pump by making it possible to freely adjust the eccentricity e between the inner and outer rotors. Each tooth of the inner rotor includes a tooth bottom 4 defined by hypocycloidal curves, an engaging portion 3 to be brought into engagement with the outer rotor and defined by involute curves, and a tooth top 2 defined by a predetermined curve such as a part of a circle or an oval or an epicycloidal curve.

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.