Patent ID: 7626298

Claim:
An electric motor comprising: a substantially toroidal inner circumferential side rotor and an outer circumferential side rotor that are positioned so as to have the same axis of rotation and are provided with permanent magnets that are arranged in a circumferential direction; a planetary gear mechanism including: a first ring gear that is formed coaxially and integrally with the outer circumferential side rotor; a second ring gear that is formed coaxially and integrally with the inner circumferential side rotor; a first planetary gear that meshes with the first ring gear; a second planetary gear that meshes with the second ring gear; a sun gear that meshes with the first planetary gear and the second planetary gear; and a first planetary carrier that rotatably supports one of the first planetary gear and the second planetary gear and that is able to pivot around the axis of rotation; and a pivot device that is connected to the first planetary carrier and that, by pivoting the first planetary carrier by a predetermined pivot amount around the axis of rotation, alters a relative phase between the inner circumferential side rotor and the outer circumferential side rotor.