| 摘要 |
PROBLEM TO BE SOLVED: To obtain smooth power transmission without lowering the strength of a flat gear, in a power steering device in which the rotation of a worm gear driven by an electric motor is transmitted to a transmission shaft via the resin-made flat gear. ! SOLUTION: A flat gear 9 is formed of a thin-thickness part 9a at a side near a worm gear 6 and a heavy-thickness part 9b at a side apart from the worm gear 6 by making a portion fixed to the flat gear 9 out of a transmission shaft 3 as an eccentric part 3a which is displaced to a side of the worm gear 6 in a neutral state. The thin-thickness part 9a of the flat gear 9 is the highest in a use frequency, however, a thermal expansion amount by a temperature change is small in a point of the thin-thickness part 9a, a change amount of backlash is also small, and thereby power can be smoothly transmitted without causing wobbling and the generation of noise. Furthermore, since it is not necessary to reduce a volume of the flat gear 9, a crack resultin |
