Patent ID: 7326143

Claim:
A rotary actuator comprising: a motor having a rotor including a rotor core fixed on a rotor shaft and a stator disposed at a radial outer side of said rotor core; and a reduction gear unit reducing a rotational speed of said rotor shaft, including an eccentric portion causing eccentric rotations and a sun gear disposed via a sun gear bearing on an outer cylindrical surface of said eccentric portion of said rotor shaft to cause swing and rotational motion and disposed adjacently to said rotor core in an axial direction of said rotor shaft, wherein said sun gear bearing includes roller members disposed adjacently and parallel to each other in the axial direction so as to form a double-bearing arrangement, said reduction gear unit is formed as an inner gearing planetary reduction gear unit including said sun gear, a ring gear meshing with said sun gear, and transmitting mechanism transmitting rotation of said sun gear to an output shaft, said rotor core is formed to have, at a radially inner portion thereof, an axially extending space opened toward said reduction gear unit, and at least one of said roller members of said double-bearing arrangement is partly disposed in said axially extending space.