Hitachi Astemo Ltd.

Koji Numakura

Matahiro Komuro

Kotaro Shiino

Hisamitsu Hatou

Shintaro Tsujimi

A steering operation input apparatus is for allowing a predetermined neutral position to be acquired regardless of a direction in which a nut is mounted. In a mechanical stopper mechanism, a central position of the nut in an axial direction aligns with a central position of a crest and a central position of a root of an externally threaded portion with a steering wheel in a neutral state. A first imaginary line extends in a direction perpendicular to a rotational axis and passes through the crest and the root, and a second imaginary line extends perpendicularly to the first imaginary line on a line of the rotational axis in a cross section perpendicular to the rotational axis at the central position of the nut, and a pin is symmetric about the first imaginary line and asymmetric about the second imaginary line.

Steering operation input apparatus

An object of the present invention is to provide a ball screw having a structure in which a screw shaft and a nut satisfy required performance and having improved durability, a method for manufacturing the ball screw, a power steering device, and a method for manufacturing the power steering device. A ball screw according to the present invention includes: a nut made of a steel substrate having an inner peripheral surface on which a female screw is formed; a screw shaft that is combined with the nut and is made of a steel substrate having an outer peripheral surface on which a male screw facing the female screw is formed; and a plurality of balls arranged between the female screw and the male screw. A surface of the nut in contact with the ball and a surface of the screw shaft in contact with the ball each have carburized layers. A carbon concentration in the carburized layer of the nut is higher than a carbon concentration in the carburized layer of the screw shaft.

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Hitachinaka, Japan

Koji Numakura