| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw mechanism with a bearing which is capable of being reduced in outer diameter, and being elongated in service life. SOLUTION: This device has a rolling bearing 16 for supporting a rotational nut 14 of a ball screw mechanism 13. An inner race rolling surface 45 of the rolling bearing 16 is integrally formed on an outer periphery surface of the rotational nut 14. Accordingly, the ball screw mechanism 13 and the bearing 16 are coupled into an integrated ball screw mechanism 40 with a bearing. In an electric power steering device, a part of a telescopic steering shaft 2 is formed as a ball screw shaft 2a of the ball screw mechanism 13. A rotor for a steering force assisting electric motor is fittedly coupled to the rotational nut 14. |
