To provide such a valve device as not allowing any interference between a valve element and a housing even if the valve device is exposed to a high temperature.
The present invention is related to such a circumstance that a catalytic valve 8 for opening/closing exhaust passage upstream from a catalytic converter located downstream, a bypass passage branching upstream from the catalytic valve 8 and detouring around the catalytic converter located upstream and a bypass valve 9 for opening/closing the bypass passage are provided, valve shafts 12, 14 of two valves 8, 9 are coaxially aligned, one end of the valve shaft 14 of the bypass valve 9 is assigned to be a fixed end in this shaft direction while the other end is assigned to be a free end and a screw joint 15 is provided between this free end and the valve shaft 12, the twist direction of the screw engraved on this screw joint 15 is assigned to be a direction to give turning rotation in the opening direction of the bypass valve 9 when the above-mentioned free end is displaced to the catalytic valve 8 and an actuator for giving turning motion to the valve shaft 12 is provided on the catalytic valve 8.
ISHIZUKA TAKASHI
SATO KENICHI
ISHIHARA KOJI
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