Air intake device having a throttle valve bypass passage with a slanted outlet surface

摘要

A main passage (18) for supplying intake air to an internal combustion engine in a controlled manner and a bypass passage (20) bypassing the main passage for supplying air to the engine at its idling state are formed in an air-intake device (10). A slanted surface (60) along which a bypass air flows is formed at the downstream end of the bypass passage (20), so that a bypass air-stream (B) smoothly joins a main air-stream (M) with a small joining angle ( C ) without generating noises. The downstream end of the bypass passage may be enlarged to reduce a speed of the bypass air-stream and to thereby further reduce noises.