Emission gas recycling equipment having butterfly valve

摘要

Emission gas recycling equipment includes a passage for recycling a part of an emission gas and a control valve for controlling an amount of the part of the emission gas. The control valve includes: a housing having a pipe portion; a butterfly valve accommodated in the pipe portion rotatable in a first direction and a second direction; a seal ring for sealing a clearance; and valve open/close operation means for stopping the butterfly valve at the valve full close position after the valve open/close operation means operates the butterfly valve to open and to close equal to or more than one cycle across the valve full close position at the time when the engine stops or after the engine stops.