| 摘要 |
PROBLEM TO BE SOLVED: To obtain a larger torque ratio from a drive member to an output member by an electric motor without enlarging the axial dimension or the outside diameter of a rotation ratio variable mechanism. SOLUTION: An input-side rotating body 41 integrally rotating with a steering shaft 12 and an output-side rotating body 42 integrally rotating with an output shaft 13 are totatably supported. A rotary shaft body 43 is rotatably supported. Multiple input-side planetary gears 74 supported to a carrier 44 are geared with an input-side ring gear 52 provided in the input-side rotating body 41 and an input-side sun gear 70 provided in the rotary shaft body 41. Multiple output-side planetary gears 75 supported to the same carrier 44 are geared with an output-side ring gear 62 provided in the output-side rotating body 42 and an output-side sun gear 71 provided in the rotary shaft body 43. The number of teeth of the output-side ring gear 62 is made to increase by 5% or less relative to the number of teeth of the input-side ring gear 52. An electric motor 96 with the rotary shaft body 43 set to the rotary shaft is provided. |
