| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable valve timing mechanism for an engine reducing a manufacturing cost of a cover member by reducing a deformation amount of a cover member due to heat treatment. SOLUTION: A sliding contact surface 56 of a cover member 26 is hardened by irradiating laser beam 66. Since only the sliding contact surface 56 which requires strength is hardened by irradiation of laser beam 66 and heat treatment is applied only on the minimum part area-wise and depth-wise, deformation of the cover member 26 is thereby greatly reduced, and manufacturing cost of the cover member 26 is reduced. COPYRIGHT: (C)2008,JPO&INPIT
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