| 摘要 |
PURPOSE:To reduce abnormal noise by providing a section meshing a small reduction gear with a large reduction gear in a final reduction device with an attenuating force generating means which attenuates relative rotating force between both of the gears when the fluctuation in torque to the direction to which a gap between them is put close, is inputted. CONSTITUTION:Each groove section 32 is provided for the shaft section 12a of a small reduction gear 15 at its four places so that permanent magnets 34, 34a through 34c are fitted in each of the aforesaid places to the circumferential direction while electromagnets 44 and 46 are fixed within outer covers 40 and 40a. When coils 44c and 46c are energized, each paired end section 44a and 44b, and 46a and 46b becomes each of magnetic poles which are relatively opposite in polarity. A control circuit 50 detects the opening speed V of an accelerator so as to compare it with a limit speed Vs at which speed abnormal noise in a driving system occurs. And when V is less than Vs, the coils 44c and 46c are de-energized. And when V is equal to or more than Vs, they are energized. In this case, an electrode is switched depending on the rotating position of a small gear 12 in order to have magnetic force acted to the direction that the gear 12 is intercepted in rotation while the impact force of the gear 12 and a large reduction gear 14 is made to be little when respective gear teeth come in contact with each other so that abnormal noise in the driving system is reduced.
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