| 摘要 |
PROBLEM TO BE SOLVED: To achieve a structure that can strike a balance at high level between securing of fatigue strength for steering force relating to at least one steering force transmission shaft among a plurality of steering force transmission shafts and securing of absorption performance of impact energy applied along with impact accident and running on a curbstone of a steering wheel.SOLUTION: In a base end nearest part of a pinion shaft 8a that constitutes a steering gear unit 7a that is a kind of a steering force transmission shaft, a small diameter part 28 serving as a part that absorbs impact energy is installed. Together with this, hardness distribution of a mode where hardness of an outside diameter part is raised compared with hardness of an inner diameter part is given to this small diameter part 28. This hardness distribution is given to this small diameter part 28 by a method or the like to subject shot peening work for an outer peripheral surface of this small diameter part 28 after forming this small diameter part 28.SELECTED DRAWING: Figure 1 |
