| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power steering device having a superior durability and a high reliability for improving a lubricating state between a worm gear and a worm wheel constituting a gear reducer mechanism, producing no uncomfortable sound such as a tooth striking sound or vibration sound and the like. SOLUTION: A worm 32 acting as a driving wheel is made of metal and a hard carbonic film is formed at the surface of a tooth part. In addition, a worm wheel 31 acting as a driven gear is provided with a cylindrical resin part 43 integrally formed by polyamide resin at an outer circumferential surface of a metallic core 42, and an outer circumferential surface of the resin part 43 has gear teeth 44. The hard carbonic film at the surface of the tooth of the worm 32 is formed by a plasma CVD process and a plasma ion implanting process and the like. The hard carbonic film is formed at the surface of the teeth at the worm 32 to cause a wetness for grease to be improved, enable a lubricating characteristic between the gears to be improved and then it is possible to provide an electric power steering device having a longer life and a higher reliability than those of the prior art. COPYRIGHT: (C)2004,JPO&NCIPI
|
