Jtekt Corporation

Honda Motor Co., Ltd.

Toyota Jidosha Kabushiki Kaisha

Koyo Seiko Company, Ltd.

Hideo Kometani

Hayato Miyakawa

Nobuyuki Taoka

Takumitsu Otani

Agen Nishikido

Masashi Fujimoto

Nariaki Sakamoto

Ippei Yamazaki

Eiji Kasai

Shuji Fujita

Hajime Tanaka

Norihisa Nishikawa

Junro Yamamoto

Yasunori Shintani

Kei Nakate

Isao Shintani

Yoshiyuki Maenaka

Hisatake Yamada

A rack-and-pinion steering system includes a pinion shaft having pinion teeth, a rack shaft on which rack teeth are formed which mesh with the pinion teeth; and a rack bush which supports the rack shaft slidably in an axial direction thereof. An outer circumferential surface of the rack shaft includes a first area which is a concave formed on an outer circumferential surface of the rack shaft and extending in the axial direction and a second area which is an area of the outer circumferential surface excluding the first area and lies adjacent to an end portion of the first area in the axial direction. The rack teeth are formed in the first area. A chamfered portion or a rounded portion is provided on a boundary between the end portion of the first area and the second area to chamfer or round a corner portion on the boundary.

Steering system

A rack bush for supporting a rack shaft in a rack-and-pinion steering system so that the rack shaft slides in an axial direction thereof includes a teeth side support portion and a back side support portion. Rack teeth are formed in a first area of an outer circumferential surface of the rack shaft. The teeth side support portion contacts a second area of the outer circumferential surface to support the rack shaft from a teeth side where the rack teeth are formed. The second area lies adjacent to the first area in the axial direction. The back side support portion contacts a third area of the outer circumferential surface to support the rack shaft from a back side other than the teeth side. The third area is positioned out of the first area in a circumferential direction around an axis of the rack shaft.

Rack bush and steering system

A steering system includes a rack shaft that extends in an axial direction so as to pass through a housing and including a first rack and a second rack on an outer circumference of the rack shaft. The first rack and second rack are separated from each other in the axial direction. The first pinion shaft includes a first pinion that has helical teeth and meshes with the first rack, and a second pinion shaft includes a second pinion that has helical teeth and meshes with the second rack. The first pinion shaft and the second pinion shaft are on the same side of the rack shaft. A rack bush is between the pinion shafts in the axial direction of the rack shaft, held by the housing so as to support the rack shaft slidably in the axial direction, and limits a movement of the rack shaft in a direction parallel to both of the pinion shafts.

A rack shaft supporting device includes a support yoke, a plug that closes the other opening of an accommodation chamber, a ball screw mechanism between the support yoke and the plug, and a torsion urging member between the ball screw mechanism and the plug. The ball screw mechanism includes: a first threaded portion in which a first thread groove is formed; a second threaded portion in which a second thread groove is formed; and balls arranged in a rolling path formed of the first thread groove and the second thread groove. The torsion urging member rotates the second threaded portion relative to the plug and moves the second threaded portion toward the support yoke.

Rack shaft supporting device and steering system using the same

When it is determined that the torque output from the electric motor abnormally fluctuates or the torque output from the electric motor varies between clockwise and counterclockwise turning operations of the driver's steering wheel, the steering assist control is continued if the vehicle speed v is equal to or lower than the reference speed v. In this case, the width of the dead band of the steering torque in the assist map used to calculate the target assist torque is increased. Thus, only in a case where the vehicle is moving at a low speed and the driver's steering wheel is operated with a great force, the steering assist torque is produced to alleviate the burden on the driver. In the other cases, the electric motor is stopped to minimize a sense of discomfort in the steering operation.

Electric power steering apparatus and method for controlling the electric power steering apparatus

An elastic support assembly for an electric power steering apparatus in which a worm shaft is supported movably in a rotation axis direction through the elastic support assembly includes: a pair of first and second members relatively moving in the rotation axis direction according to a movement of the worm shaft; an elastic body provided between the first and second members in the rotation axis direction; and a cover which covers an outer periphery part of the elastic body from a radial direction of the worm shaft and is connected to the first member.

Elastic support assembly for electric power steering apparatus

Growing community of inventors

Nara, Japan

Hideo Kometani