US Patent 7464692 Intake air control valves

An intake air control valve has a bore defining member and a butterfly-type valve member that includes a shaft and a valve body. The valve body has a pair of valve portions joined to the shaft and rotatable between a fully closed position and a fully opened position; Each of the valve portions has a central portion and opposite end portions along a direction of the rotational axis of the valve member. The thickness of each of the valve portions gradually increases from the central portion toward the end portions.