Patent ID: 7234444

Claim:
Emission gas recycling equipment comprising: an emission gas recycling passage for recycling a part of an emission gas from a combustion engine to an air intake side of the engine; and a recycling emission gas amount control valve for controlling an amount of the part of the emission gas, which is recycled into the air intake side through the emission gas recycling passage, wherein the recycling emission gas amount control valve includes: a housing having a pipe portion to provide a part of the emission gas recycling passage; a butterfly valve rotatable in a valve opening direction and a valve closing direction with respect to a rotation center axis, wherein the butterfly valve is accommodated in the pipe portion to be openable and closable in a rotational angle range between a valve full open position and a valve stop position, at which the butterfly valve is rotated by a predetermined degree from the valve full open position; a seal ring having a substantially ring shape for sealing a ring shape clearance by using an elastic deformation force in a radial direction, wherein the ring shape clearance is formed between an inner wall of the pipe portion and an outer wall of the butterfly valve in a case where the butterfly valve is positioned at the valve full close position, and wherein the seal ring is accommodated in an outer diameter portion of the butterfly valve; valve position holding means for stopping the butterfly valve at the valve stop position passed over the valve full close position at the time when the engine stops or after the engine stops; and ring outer diameter holding means for holding an outer diameter of the seal ring to be equal to an inner diameter of the pipe portion at the valve stop position.