| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power steering device reducing the number of part items and its weight by preventing slippage between a large gear and a ball nut, and also to provide a manufacturing method of the electric power steering device. SOLUTION: The large gear 8 is constituted of a metallic tooth core part 8b and a synthetic resin made tooth member 8a. The tooth core part 8b is peripherally provided on an outer periphery 7a of the metallic cylindrical ball nut 7 so as to be integral with it. The tooth core part 8b is rectangular on its cross-section in the axial direction, a projected part 8c a cross-section in the axial direction of which is roughly rectangular is peripherally provided in width smaller than width of the tooth core part 8b on a central part of an outer periphery of the tooth core part 8b, and dimensions in the axial direction of the projected part 8c are formed so that the outer peripheral side becomes longer than the inner peripheral side. The tooth member 8a is peripherally provided in the same width as the tooth core part 8b on the outer periphery of the tooth core part 8b, and gear cutting work is applied on an outer peripheral head end part. COPYRIGHT: (C)2005,JPO&NCIPI
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