Hitachi Astemo Ltd.

Kotaro Shiino

Matahiro Komuro

Toshiyuki Ajima

Junya Takahashi

Shigehisa Aoyagi

Shinya Kasai

Hisamitsu Hatou

Koji Numakura

Shintaro Tsujimi

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.

Ball screw, method for manufacturing ball screw, power steering device, and method for manufacturing power steering device

An object of the present invention is to provide a steering control device capable of reducing a steering amount while securing operability of a driver according to a traveling condition. A steering control deviceforming a steer-by-wire system, which has no physical connection between a steering shaft by a driver and an actual steered angle of a vehicle wheel, the steering control device including an actual steered angle calculation unitthat determines the actual steered angle based on a steering angle and a steering torque generated on the steering shaft. The actual steered angle calculation unitcontrols the actual steered angle based on the steering torque in a region where the steering angle is equal to or smaller than a predetermined value, and controls the actual steered angle based on a parameter different from the steering torque when the steering angle is larger than the predetermined value or a changed steering torque gain from when the steering angle is smaller than the predetermined value.

Steering control device

An object of the present invention is to provide a power conversion device including a plurality of inverter circuits connected in parallel to a load, the power conversion device being capable of performing control with a smaller number of microcomputers, having high reliability, and being advantageous for miniaturization and cost reduction. Provided are: a plurality of inverter circuits connected in parallel to a load; a microcomputer which controls the plurality of inverter circuits; a plurality of signal selection units which select a drive signal of each of the plurality of inverter circuits; and a first transmission path and a second transmission path which are connected in parallel between the microcomputer and the plurality of signal selection units and transmit the drive signal of each of the plurality of inverter circuits from the microcomputer to each of the plurality of signal selection units. Each of the plurality of signal selection units selects any one of a first drive signal transmitted from the first transmission path and a second drive signal transmitted from the second transmission path.

Power conversion device

Growing community of inventors

Hitachinaka, Japan

Kotaro Shiino