| 摘要 |
PURPOSE:To lower the noise level of an engine effectively, by connecting resonance chambers to an air intake passage via a plurality of members in the form of communicating pipes, communicating the resonance chambers with each other via a connecting pipe having therein an ON-OFF valve, and controlling operation of the ON-OFF valve according to the engine speed. CONSTITUTION:In an engine, in which an intake duct 13 is connected to an air cleaner 11 connected on the upstream side of a carburetor 10 via an air intake pipe 12 and the opening 13a at the top of the intake duct 13 is opened to the atmosphere, a first and a second members 15, 16 in the form of communicating pipes are connected to intermediate portion of the intake pipe 12 or the intake duct 13 separately from each other. The other ends of the tubular members 15, 16 are opened respectively in a first and a second resonance chambers 17, 18 consisting of enclosed spaces, and the two resonance chambers 17, 18 are communicated with each other via a connecting pipe 19. Further, an ON-OFF valve 21 is disposed in the connecting pipe 19, and operation of the ON-OFF valve 21 is controlled by a micro-computor 23 by the aid of an actuator 22 such that the resonant frequency equal to the dominant frequency component of the intake noise varied with the engine speed can be obtained. |
