Patent ID: 8342149

Claim:
An air intake device for an engine, comprising: a throttle body having an air intake path; a butterfly throttle valve that has a valve shaft rotatably supported on the throttle body and that opens and closes the air intake path; a throttle drum connected to one end of the valve shaft so as to open and close the throttle valve; a throttle sensor that is connected to another end of the valve shaft and that detects a degree of opening of the throttle valve; a bypass connected to the air intake path and bypassing the throttle valve; a bypass valve that opens and closes the bypass; and a bearing boss, supporting an end part, on the throttle drum side, of the valve shaft being integrally and projectingly provided on one side wall of the throttle body, wherein the bypass is formed so as to surround the bearing boss and surround a return spring of the throttle drum, the return spring being mounted so as to surround the bearing boss.