Patent ID: 7168682

Claim:
Emission gas recycling equipment comprising: a passage for recycling a part of an emission gas from an exhaust side to an intake side of a combustion engine; and a control valve for controlling an amount of the part of the emission gas, which is recycled into the intake side through the passage, wherein the control valve includes: a housing having a pipe portion to provide a part of the passage; a butterfly valve accommodated in the pipe portion rotatable in a first direction and a second direction, wherein the first direction is defined as a rotational direction of the butterfly valve from a valve full open position to a valve full close position, and the second direction is opposite to the first direction; a seal ring for sealing a clearance 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, wherein the seal ring is accommodated in an outer diameter portion of the butterfly valve; and valve open/close operation means for stopping the butterfly valve at the valve full dose 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, and wherein the butterfly valve is rotatable in a range between the valve full open position and a predetermined position, at which the butterfly valve is rotated by a predetermined degree from the valve full close position in the first direction, the valve open/close operation means includes a power unit for rotating the butterfly valve in the first direction and the second direction, the valve open/close operation means includes a first spring and a second spring, the first spring applies a force to the butterfly valve in the first direction from the valve full open position to the valve full close position, and the second spring applies a force to the butterfly valve in the second direction from the predetermined position to the valve full close position.