Abstract
By shifting natural frequencies of the internal transmission system of combustion impact power in a diesel engine and by changing the fuelinjection timings in the case with two-stage combustion, we made a natural frequency of the internal transmission system coincided with a combustion-impact cancelling frequency and investigated the influence of the present method on the radiated noise characteristics. We confirmed that we can make the natural frequency of the piston-connecting rod vibration higher and reduce the engine noise by shortening thinned portion of connecting rod. We also confirmed that the combination of changing the natural frequency of the piston-connecting rod vibration and noise cancelling spike combustion is effective in the engine noise reduction.
