| 摘要 |
PURPOSE:To efficiently reduce an intake air noise over the entire range of engine rotation, by connecting a plurality of resonance chambers of different volumes through a passage provided with a switch valve to an engine intake system on the way thereof, and controlling the valve in response to engine speeds to select any appropriate resonance chamber. CONSTITUTION:A plurality of resonance chambers 6a-6c having different volumes are connected through a communication passage 4 and a rotary valve 5 to an intermediate position of an outside air intake passage 3 leading to an air cleaner 2 mounted on an internal-combustion engine 1. An engine speed sensor 7 for outputting a signal responsive to rotational speeds of a crank shaft is mounted in the engine 1. Such an output is fed to a controller 8, and thereby the rotary valve 5 is selectively operated by a motor 9 in response to the engine speeds. Accordingly, the resonance chambers 6a-6c leading to the outside air intake passage 3 are selected by selectively operating the rotary valve 5 responsive to the rotational speeds of the engine 1, thereby efficiently reducing an intake air noise over the entire range of engine rotation. |
