| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw for an electric power steering enabling the improvement of torque characteristics. SOLUTION: This ball screw 5 is used for the rack assist type electric power steering having a screw shaft 5a and a rack 3a formed on a steering shaft 3. The contact anglesα<SB>1</SB>andα<SB>2</SB>(α<SB>1</SB>=α<SB>2</SB>) of the ball screw groove 6 in the screw shaft 5a of the ball screw 5 and the contact anglesθ<SB>1</SB>andθ<SB>2</SB>(θ<SB>1</SB>=θ<SB>2</SB>) of the ball screw groove 7 in a nut 5b are differentiated from each other. Specifically, the contact anglesα<SB>1</SB>andα<SB>2</SB>of the ball screw groove 6 in the screw shaft 5a are made smaller than the contact anglesθ<SB>1</SB>andθ<SB>2</SB>of the ball screw groove 7 in the nut 5b. COPYRIGHT: (C)2005,JPO&NCIPI
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