Patent attributes
The present application discloses a steering assistance device, including: a motor configured to output a drive force in accordance with a steering force applied to a steering shaft; and a speed reducer including: a gear section configured to rotate and oscillate in accordance with the drive force; an outer cylinder having an internally toothed ring formed thereon, the internally toothed ring being configured to mesh with the gear section; and a carrier configured to rotate in accordance with rotation and oscillation of the gear section and output a steering assistance force to a steering mechanism, the steering mechanism being configured to steer vehicle wheels in accordance with rotational operation applied to a steering wheel. The engagement ratio between the gear section and the internally toothed ring is from 25 to 100%.