PURPOSE: To effectively reduce a synchronizing intake noise in idling in a compact structure by connecting a resonance type noise eliminator which eliminates noise through resonance with a synchronous frequency of a pressure vibration characteristic of the upper stream of a throttle body, from an intake passage at the upper stream of the throttle body to a branch idle passage.
CONSTITUTION: In an intake device constituted by an air cleaner 7, an upper stream intake passage 8, a surge tank 8 and an independent intake passage 6 of each cylinder, the upper stream intake passage 8 is constituted in such a structure that its columnar vibration characteristic is synchronized with a pressure vibration frequency generated corresponding to an intake pulsation at an engine revolution number in idling and excited according to setting of the length and area of the passage. And in order to attenuate pressure vibration in idling, a resonance type noise eliminator 29 which resonates with a synchronous frequency and eliminates noise is connected to an idle passage for supplying an intake in idling with bypassing a throttle body 15. This resonance type noise eliminator 29 is constituted by a pipe member 30 made of a rubber and so on, and its one end part 30a is connected to a curved part of the idle passage 25.
YAHIRO TETSUJI
MORIMUNE TATSUTOMO
