Jtekt Corporation

Toyota Jidosha Kabushiki Kaisha

Masayoshi Asakura

Tetsuya Kaneko

Takashi Hara

Toshihiro Asakura

Masashi Yamaguchi

Yoshiaki Asahara

Hirokazu Kondo

Hirotsune Suzuki

Satoshi Fujita

Ryuji Shibata

Tatsuhiro Yamamoto

Masafumi Takahashi

Kiyoshi Uchiyama

Shunji Inoue

A rack housing and a reduction drive housing accommodate a ball screw mechanism and a reduction drive. Within the rack housing and the reduction drive housing, a gap is provided between the left end of a nut and the rack housing, and a gap is provided between the right end of the nut and the rack housing. A groove serving as a communication path in communication with the gaps on both axial sides of the nut is provided in the outer circumferential surface of the nut. The groove is provided so as to avoid a recirculation path provided in the nut. The groove is provided axially and rectilinearly from the end of the nut that is located on the side opposite to a flange, to the flange and is provided along the flange.

Steering apparatus

A steering apparatus includes a steered shaft; a rack housing; a ball screw nut; a bearing disposed between an inner peripheral surface of the rack housing and an outer peripheral surface of the ball screw nut, the bearing supporting the ball screw nut such that the ball screw nut is rotatable with respect to the rack housing; and a tubular rack boot covering an axial end portion of the rack housing. The rack housing includes a partition wall protruding radially inward from a cylindrical inner peripheral surface of the rack housing and separating a ball screw chamber housing the ball screw nut and an inner chamber of the rack boot. The partition wall has a through-hole through which the steered shaft extends, and a drain passage provided vertically below the through-hole and providing communication between the ball screw chamber and the inner chamber of the rack boot.

A steering apparatus includes a steering shaft; a steered shaft; a ball screw mechanism; and a motor. A plurality of rolling elements includes large-diameter rolling elements and small-diameter rolling elements. A prescribed diameter difference is set such that when a magnitude of power transmitted between a first screw groove and a second screw groove is a prescribed value or less, only the large-diameter rolling elements transmit the power between the first screw groove and the second screw groove, and when the magnitude of the power transmitted between the first screw groove and the second screw groove exceeds the prescribed value, both the large-diameter rolling elements and the small-diameter rolling elements transmit the power.

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.

Growing community of inventors

Okazaki, Japan

Masayoshi Asakura