| 摘要 |
PURPOSE:To obtain a favorable steering feeling throughout the operating range of a steering wheel, by providing a region wherein a rack and a pinion are engaged with each other as arcuate gears, so that an increase in the steering force is reduced in a desired region of the operating range of the steering wheel. CONSTITUTION:The pinion 1 is provided with a plurality of helical teeth having the same helix angle and having a uniform tooth form along the tooth trace, which tooth form is an arc of a circle the center of which is located on the pitch circle in a cross section orthogonal to the axis. The rack 2 is so formed that the gear ratio between the rack 2 and the pinion 1 is changed in a region extending from a point near a neutral position of the steering wheel to a cutting-in region of the steering wheel. The rack 2 has a fixed high gear ratio in the cutting-in region (c-d) of the steering wheel. The radius of curvature of the arc of the bottom land of the rack 2 is set to be slightly larger than that of the arc of the tooth crest of the pinion. The gear ratio is gradually reduced in an intermediate region (b-c) extending from the cutting-in region (c-d) of the steering wheel to a point near the neutral position of the steering wheel. |
