Jtekt Corporation

Toyota Jidosha Kabushiki Kaisha

Togo Seisakusyo Corporation

Toyoda Koki Kabushiki Kaisha

Jtekt Coporation

Toshihiro Asakura

Takuya Nakayama

Keisuke Ogawa

Tetsuya Kaneko

Takashi Hara

Hiroyuki Toyoda

Yuji Nakamura

Kenji Hayashi

Toshiaki Ogata

Hirotsune Suzuki

Yukihiko Kanayama

Satoshi Fujita

Masatoshi Fujimoto

Yuzo Hirakawa

Hirotsugu Kusano

Masayoshi Asakura

Satoru Uemura

Takashi Fuwa

Hirokazu Tojo

Hirofumi Kuwabara

Yuichi Yamanaka

Shigeyuki Sugimori

Yoshio Yunokawa

An electric power steering system includes: a steered shaft, a housing containing the steered shaft therein in a movable manner; a ball screw nut engaged threadedly to the steered shaft via a plurality of balls and configured to move the steered shaft in an axial direction; a double row angular contact ball bearing configured to retain the ball screw nut and to support the retained ball screw nut rotatably relative to the housing; a wall portion placed at either side of the double row angular contact ball bearing in the axial direction of the steered shaft, the wall portion being formed integrally with the housing; and an elastic member provided between the wall portion and the outer ring portion and configured to retain the double row angular contact ball bearing to be elastically displaceable in the axial direction.

Electric power steering system

There provides a ceiling surface of a deflector which secures an allowance for engagement between a rolling ball and a retainer. A ball screw device includes a ball screw shaft, a ball nut, a deflector forming a coupling passage, a rolling ball, and a retainer. The coupling passage is defined by an outer circumferential ball rolling groove, a ridge, and a ceiling surface. The ceiling surface has a first rounded portion at which a projected shape of the ceiling surface seen in an axial direction has a first radius of curvature at least such that a constant first clearance is provided between the rolling ball and the ceiling surface, and a second rounded portion at which the projected shape has a second radius of curvature smaller than the first radius of curvature and which is located on a groove bottom side of the outer circumferential ball rolling groove.

Ball screw device and steering system including ball screw device

A steering system with a reduced number of parts is provided. A driven pulley has a radially outer portion, a radially inner portion, and a connection portion that connects the radially outer portion and the radially inner portion to each other. The radially inner portion is provided with a plurality of slits at equal intervals in the circumferential direction. A plurality of retention portions are provided at portions of the radially inner portion between the slits. Lug portions are provided on the inner surface of the distal ends of the retention portions. A groove is provided in the outer peripheral surface of a ball screw nut. The lug portions of the retention portions are fitted with the groove of the ball screw nut.

Steering system

A production method of a ball screw device is provided. The ball screw device includes a ball screw portion, a ball nut, rolling balls, and a retainer. The production method of the ball screw device includes: a first preparation step of preparing a nut subassembly as a standard product; a second preparation step of preparing the ball screw portion in plurality by types as ranked products; a measuring step of measuring a relative displacement in a thrust direction between the standard product and each ranked product; a determination step of determining whether the displacement meets a displacement specification; a replacing step of, if the displacement does not meet the specification, replacing the ranked product with another ranked product; and an assembling step of, if the displacement meets the specification, assembling the standard product and the ranked product into the ball screw device.

Production method of ball screw device and production method of steering system using ball screw device

A cylindrical retainer configured to retain balls in a rollable manner is provided inside a ball screw nut. The retainer has retainer grooves each having a shape of an elongated hole that extends in an axial direction of a ball screw shaft so as to be inclined at a predetermined angle. A first end of the ball screw nut and a first end of the retainer, which is one of two ends of the retainer that is closer to the first end of the ball screw nut, are spaced away from each other by a distance. The terminal end of the retainer groove closest to the second end of the retainer and a ball that is closest to the second end of the ball screw nut are spaced away from each other by a distance. The distance is set equal to or larger than the distance.

Ball screw device and steering system

A ball screw mechanism that allows a reduction in contact and friction between a retainer and a nut is provided. In a ball screw mechanism, a nut is threadedly engaged with a screw groove of a rack shaft through balls retained in a retainer groove of a retainer, and an axial force is applied to the rack shaft in accordance with rotation of the nut. The nut includes a uniform diameter portion having a uniform inside diameter and enlarged diameter portions each having an inside diameter larger than that of the uniform diameter portion. The enlarged diameter portions are provided at opposite axial ends of a region on an inner circumferential surface of the nut. The region faces the retainer groove and retainer ends adjoining to opposite axial ends of the retainer groove.

Ball screw mechanism and steering system

A ball screw device and a steering system that include a retainer having more uniform stiffness are provided. Between a rack shaft and a ball screw nut, a cylindrical retainer having a plurality of retainer grooves that retain balls in a rollable manner is provided. Each retainer groove has two short inner surfaces that intersect the extending direction of the retainer groove and two long inner surfaces that intersect these short inner surfaces and extend along the extending direction of the retainer groove. In each of interior-angle portions where the short inner surfaces and the long inner surfaces intersect, a corner round surface is formed. The radius of the corner round surface is set to be smaller than one half of the width of the retainer groove.

There is provided a steering apparatus including a fixing mechanism for fixing a driven pulley and a rolling nut to each other, the fixing mechanism configured to suppress at least one of deformation of external teeth of the driven pulley and an increase in size of a housing surrounding the driven pulley. A steering apparatus includes: a steered shaft; a ball screw mechanism including a rolling screw portion, a rolling nut, and rolling elements; a motor; a belt transmission mechanism including a drive pulley, a driven pulley, and a toothed belt; and a fixing mechanism. The fixing mechanism includes an internal thread, a cutout section, and a locknut. The cutout section is provided at a position offset, in the axial direction, from a range of second external teeth in the axial direction, and the locknut includes a locknut body, a locking lug, and a remaining portion.

Steering apparatus

A recessed portion is formed in an inner wall surface of a lower portion of a reduction gear housing (a lower wall in FIG.) in the direction of gravity and between a bearingand an outer wall of the reduction gear housing (a right side wall in FIG.). The recessed portion is formed to have such a depth that the recessed portion does not penetrate the reduction gear housing. The recessed portion is formed in the reduction gear housing within a given range in a circumferential direction with respect to the axis of a rack shaft serving as the center. A moisture sensor is mounted in the recessed portion to detect water infiltrating into a housing. The moisture sensor has a transmission circuit that operates using a water battery as a power supply source. The water battery generates power when water flows into the water battery.

Moisture sensor and steering system

A ball screw device is provided, including a retainer that can properly retain balls. The difference between a diameter being the pitch circle diameter of the ball screw device and the outside diameter of the rack shaft is set to be equal to or larger than the difference between the bore diameter of a ball screw nut and the diameter. The thickness center diameter of the retainer is set to be smaller than the diameter. Even when the inclination angle is reduced, the clearance between the inclined surfaces of each retainer groove on the radial inside can be easily set to be smaller than the diameter of the balls because the bore diameter of the retainer is set to be smaller. Thus, even when the inclination angle of the inclined surfaces is set to be smaller, the balls can be properly retained.

A torque limiter is configured from a ring body and a spring-form part provided in the ring body. The ring body includes a band-form metal plate and is bent approximately into a C-shape along the circumferential direction of a motor shaft and a lock holder. The spring-form part is formed so as to be capable of radial elastic deformation. The spring-form part is configured from main protrusions arranged in a compressed state between the motor shaft and the lock holder, and from sub-protrusions arranged in a non-compressed state. Further, grease is stored in a part or all of the concavities formed by the main protrusions and the sub-protrusions.

Torque limiter, variable transmission ratio device, and tolerance ring

A ball screw device is provided for which quality can be easily evaluated. The ball screw device includes a threaded shaft with a groove formed on an outer peripheral surface of the shaft, and a cylindrical nut whose screw-thread mates with the groove on the threaded shaft via a plurality of balls. The nut has a pair of mounting holes in each of which a deflector is installed and a communication groove that allows the mounting holes to communicate with each other and is open on the outer peripheral surface of the nut and through which the balls can roll. The width W of an opening of the communication groove is smaller than the diameter of the ball.

Ball screw device, power transfer mechanism, electric power steering apparatus, and method for manufacturing ball screw device

In an electric power steering system, there is provided a ball screw deflector configured to make it possible to easily measure the whole length of each of deflector pieces. A mating face of each of the deflector pieces and end faces of the deflector pieces are parallel to each other, and have an angle corresponding to a lead angle of a ball screw portion. Thus, it is possible to reduce the amount of material required to form each of the deflector piece pieces. In addition, it is possible to easily measure the overall length of each of the deflector pieces with the use of measuring equipment such as a vernier caliper.

Ball screw deflector

This torque limiter is configured from a ring body and a spring-form part provided in the ring body. The ring body comprises a band-form metal plate and is bent approximately into a C-shape along the circumferential direction of a motor shaft and a lock holder. The spring-form part is formed so as to be capable of radial elastic deformation. The spring-form part is configured from main protrusions arranged in a compressed state between the motor shaft and the lock holder, and from sub-protrusions arranged in a non-compressed state. Further, grease is stored in a part or all of the concavities formed by the main protrusions and the sub-protrusions.

An electric power steering apparatus transmits rotational force of a motor to a rack shaft via a driver pulley, a belt, a driven pulley, and a ball nut. A ball bearing and the driven pulley are fitted to the outer circumferential surface of the ball nut. Also, the ball nut is rotationally supported to the inner circumferential surface of a housing via the ball bearing. A female thread portion is formed on the inner circumferential surface of the driven pulley. The ball nut has a male thread portion formed in a first end and a flange formed in a second end. By fastening the male thread portion and the female thread portion to each other, the ball bearing is clamped between the flange and the driven pulley, while the ball nut and the driven pulley are fastened to each other.

Growing community of inventors

Chiryu, Japan

Toshihiro Asakura