| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve such a problem that decrease in the power transmission efficiency between an intermediate gear and an output gear in a deceleration mechanism by gear wear in the intermediate gear and the output gear due to long-term use tends to increase (amplify) a torque fluctuation by a cogging torque on an output shaft of the deceleration mechanism. <P>SOLUTION: A return mechanism of an electric actuator that drives an EGR valve 1 to a valve-opening direction is composed of: a return spring 7 configured to apply an elastic force urging the EGR valve 1 in a valve closing direction with respect to an output shaft 13 or a last gear 16 of the deceleration mechanism; and a spiral spring 8 configured to apply an elastic force urging the EGR valve 1 to a valve closing direction with respect to a motor shaft 11 and a pinion gear 14 of a DC motor M. Thus, even when the power transmission efficiency of the deceleration mechanism disposed between the motor shaft 11 and the output shaft 13 decreases in long-term use, a torque fluctuation (irregular rotation or vibration) by cogging torque occurring on the motor shaft 11 is not easily transmitted to the output shaft 13. <P>COPYRIGHT: (C)2013,JPO&INPIT |
