Jtekt Corporation

Takashi Hara

Toshihiro Asakura

Masayoshi Asakura

Tetsuya Kaneko

A fitting recess portion that connects fitting holes to each other is formed in a peripheral face of a ball screw nut. A circulation member includes a pair of fitted portions that are fitted in the fitting holes, and a connecting portion that provides communication between the fitted portions. A communication groove that has an opening on the fitted end side of the connecting portion and that extends in the axial direction is formed in the connecting portion. When the connecting portion is fitted in the fitting recess portion and the opening of the communication groove formed in the connecting portion is blocked by a bottom portion of the fitting recess portion, a second path that forms a return path together with first paths formed in the fitted portions is formed.

Ball screw unit and electric power steering apparatus

The ball screw apparatus includes a returning way Lby mounting a circulating memberin mounted holesformed in the ball screw nut. The ball screw nutincludes a base portionand an expanding portion. In the base portiona distance from an axis center Oof the rack shaftto a bottom portionof the nut side screw grooveis constant, and in the expanding portionthe distance is larger than that of the base portion. The expanding portionincludes a connecting area

Ball screw apparatus and electric power steering apparatus

In an electric power steering system, multiple cutouts () are formed in a flange portion () formed on an axial end portion () of a ball screw nut () of a ball screw device that drives a rack shaft. In addition, a motor shaft () has a thin-plate portion () that extends on the radially outer side of the ball screw nut (). When the thin-plate portion () that extends from the motor shaft () is swaged into the cutouts () that serve as engagement recesses that have side walls in the circumferential direction, the rotation of the ball screw nut () relative to the motor shaft () is restricted.

Electric power steering system

In an electric power steering system, a ball screw nut () of a ball screw device that drives a rack shaft is screwed to an axial end portion () of a motor shaft () when a threaded portion () of a hollow threaded shaft () formed at an axial end portion () of the ball screw nut () is screwed to a threaded portion () formed in the inner periphery of a motor shaft (). A flange member () that is larger in diameter than the ball screw nut () is fitted to the outer periphery of the axial end portion () of the motor shaft (). The flange member () is formed in such a manner that when the rotation of the flange member () is restricted, the rotation of the ball screw nut () and the motor shaft () in the same direction is restricted when the ball screw nut () is screwed to the motor shaft ().

A flange member, which is formed as a separate body from a motor shaft, is screwed to an endof the motor shaft. The flange memberfunctions as a flangeof the motor shaft. A flange, which is formed at an endof a ball screw nut, is fastened to the flangeof the motor shaft. This couples the ball screw nutto the motor shaft. A coupling memberis arranged in the joint portion between the ball screw nutand the motor shaft. The coupling memberis formed by a tubular portionand a plate flange, which extends radially outward from the outer circumferential surface of an end of the tubular portion. The tubular portionof the coupling memberis fixed to the motor shaft, and the plate flangeis fixed to the flange member

Growing community of inventors

Toyokawa, Japan

Takashi Hara