| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust gas control valve achieving both a demand for reducing noise required at a low speed state of an engine, and a demand for reducing back pressure required at a high speed state of the engine rotates at the same time and improving back pressure reducing effect in a valve opening initial stage. Ž<P>SOLUTION: The exhaust gas control device includes a valve element 2 openably and closably provided to a valve seat 1 provided in a middle of an exhaust gas flow passage in a muffler body via a support shaft 3, a coil spring 4 for biasing the control valve in the valve closing direction by abutting the valve element 2 on a seat face 12 of the valve seat 1, and a tension coil spring 5 for biasing the control valve in the valve opening direction by biasing force weaker than that of the coil spring 4. In the tension coil spring 5, a fulcrum of the tension coil spring 5 (an axis S1 of a fulcrum side support shaft 5) with respect to the rotational center of the valve element 2 (an axis S3 of the support shaft 3), and a point of action with respect to the valve element 2 (an axis S2 of a point of action side support shaft 52) are set so that biasing force does not act in the valve opening direction at least when the exhaust control valve is closed. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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