| 摘要 |
PROBLEM TO BE SOLVED: To absorb an increase in backlash with the lapse of time, in a worm and a worm wheel of a worm gear type reduction gear for transmitting rotation of an electric motor driven in response to steering to a steering mechanism, so as to keep the proper backlash over a long period. SOLUTION: The worm 21 meshed with the worm wheel 22 serves as a double lead worm, the worm 21 is press-energized from a small lead angle side to a large lead angle side by the first elastic body 31, the worm 21 is press-energized with force smaller than that of the first elastic body 31 from the large lead angel side to the small lead angle side by the second elastic body 32, the worm 21 is moved along an axial direction by a force balance between the first and second elastic bodies 31, 32 when the backlash in a meshed part between worm 21 and the worm wheel 22 is increased, and a portion smaller in a lead angle, i.e., thicker in a tooth thickness is meshed with the worm wheel 22. COPYRIGHT: (C)2004,JPO |
