| 摘要 |
PURPOSE:To obtain steering sensitivity with a sense of moderation by correcting the rack tooth surfaces of a pair of central rack teeth that are opposed to each other among the rack teeth when an elliptical type sector gear is moved in the axial direction and the backlash between the gear and rack is adjusted. CONSTITUTION:When a rack 20 screwed in a ball screw shaft 12 is reciprocated and moved by the turning of a steering shaft 15 and an output shaft 13 is rotated through a sector gear 30 with three sector teeth 31 that are engaged with the rack teeth 31 of a rack 20, the sector teeth 31 increase the amount of transfer slowly from a small diameter end (A) toward a large diameter and (B) and is teeth-cut. In addition, the pitch of a pair of central rack teeth 22 and 23 that are engaged with a central sector teeth 32 is made smaller than that of other rack teeth. In this case, when the mutually opposed tooth surfaces 22a and 23a of the said rack teeth 22 and 23 are advanced by preset distance (d) from the steering neutral position, corrected tooth surfaces 22b and 23b with a slope size are formed at the tooth tip side from the engagement line (P) with the sector teeth 32. |
