Patent ID: 8307850

Claim:
An air intake device for an engine comprising: a throttle body having an air intake path, a throttle valve that is supported on the throttle body and that opens and closes the air intake path, a bypass connected to the air intake path while bypassing the throttle valve, a bypass valve for controlling the degree of opening of the bypass, the bypass valve being formed from a tubular valve chamber having an interior thereof opening on an upstream side of the bypass and having an inner face with a metering hole opening toward a downstream side of the bypass, and a valve body that is slidably but non-rotatably fitted into the valve chamber and that opens and closes the metering hole, wherein one portion of the inner face of the valve chamber on which the metering hole opens and one portion of an outer face of the valve body opposing said one portion of the inner face and covering the metering hole are formed in the same shape so as to enable them to be in intimate contact with each other, and other portions of the inner and outer faces of the valve chamber and the valve body displaced in the peripheral direction to the opposite side to said one portions are formed so as to form a gap (g) therebetween, and wherein an inner peripheral face (A) of the valve chamber is formed as a cylindrical face, a first partial outer peripheral face (B 1 ) of the valve body covering the metering hole is formed as an arc-shaped face having a radius of curvature (R 1 ) that is the same as that of the inner peripheral face (A), and a second partial outer peripheral face (B 2 ) of the valve body on the side opposite to the first partial outer peripheral face (B 1 ) is formed as an arc-shaped face that is substantially concentric with the first partial outer peripheral face (B 1 ) and has a radius of curvature (R 2 ) that is smaller than the radius of curvature (R 1 ) of the first partial outer peripheral face (B 1 ).