Valve device

An internal combustion engine, comprising:

• a valve device;
• an intake manifold;
• and
• a supercharger, wherein
• the valve device comprises:
• a housing defining a passage therein that has a circular cross-section with a diameter, the passage extending along a center axis;
• a shaft rotatably supported by the housing;
• a butterfly valve having a disk shape and a groove formed on an outer circumferential surface, the butterfly valve being fixed to the shaft and housed in the passage to selectively open and close the passage;
• and
• a sealing member having an annular shape and fit into the groove, the sealing member being disposed coaxially with the center axis of the passage and configured to be rotatable about a rotational axis that passes through and is perpendicular to the center axis, wherein
• the groove includes a bottom and a side surface,
• the sealing member and the bottom of the groove define a clearance therebetween along a radial direction of the sealing member,
• the sealing member and the side surface of the groove define a clearance therebetween along a thickness direction of the sealing member,
• the sealing member is configured to seal between the outer circumferential surface of the butterfly valve and an inner wall of the passage, when the passage is closed by the butterfly valve, by being elastically deformed to have at least a portion of an outer circumferential surface of the sealing member come into contact with the inner wall of the passage,
• the outer circumferential surface of the sealing member is spherically shaped and in a cross-section that is perpendicular to the rotational axis and extends through the center axis has an arc surface having a diameter equal to the diameter of the passage, and
• the arc surface comes into contact with the inner wall of the passage when the passage is closed, wherein
• the valve device is disposed in a circulation passage that recirculates a portion of an exhaust gas discharged from a combustion chamber of the internal combustion engine into an intake passage,
• the butterfly valve is rotated together with the shaft to adjust a flow amount of the exhaust gas to be recirculated into the intake passage, and
• the supercharger is disposed between the intake manifold and the circulation passage.