To commonly use a steering mechanism comprising a rack and a pinion of a vehicle in which rotation directions of an input shaft and an output shaft are same, and to attain the state in which the rotation directions of the input shaft and the output shaft are same in an abnormal state and the ratio of the number of revolution of the input shaft and the output shaft becomes 1:1.
The steering angle ratio variable steering device 1 is constituted by providing a differential gear mechanism 2 provided with the input shaft 4 connected to a steering wheel; the output shaft 5 rotated in the same direction as the input shaft and connected to a steered wheel; and an assist shaft 6 connected with the output shaft of a motor and varying the ration of the number of revolution of the output shaft 5 to the number of revolution of the input shaft 4, and providing a connection means 3 for connecting the assist shaft 6 and the output shaft 5 and integrally rotating them. In an abnormal state, the output shaft 5 and the assist shaft 6 are connected by the connection means and rotation of the input shaft 4 and the output shaft 5 is performed such that the rotation directions are same and the ratio of the number of revolution becomes 1:1.
Hiromichi Kobayashi
Tomioka Kiyoshi