Researches On The Influence Of Primary Load-carry Structures On Noise And Vibration Of Diesel Engines

The noise and vibration control of engines becomes more and more attractive as the design of engines is becoming higher performance,lower fuel consumption and lighter weight.Scholars around the world have made a lot of researches about the low-noise-design of engines and have made notable improvements.But the engines are still one of the main sources of vehicle noise.So that further researches are needed in the regard.Take the high strengthened diesel engine as the research object.An accurate finite element model of the engine has been established and a harmonic analysis to the model has been carried on.Then the noise of the original diesel engine can be calculated with the combination of ATV and acoustic FEM.On the basis of the accurate finite element model,the simplified finite element model of the diesel engine has been built up.According to the variation of the design parameters of primary load-carry structures,the vibration and noise of a series of new finite element models have been calculated which are updated by the simplified and the accurate finite element model.Thus the key design elements have been determined: the width of the main bearing housing-cap,the position of engine block’s inner side panel and the thickness of engine block’s outer side panel.At last,make response surface analysis with these key design elements.The response surface model suggests the optimal values of the design parameters of primary load-carry structures to make the sound power level of the diesel engine to be reduced.Compared the sound power level of the diesel engine forecasted by the response surface modal with the sound power level forecasted by new finite element modals,the response surface modal can be considered to be accurate.Compared with the original diesel engine,the sound power level of the optimal design is 1.87 dB(A)lower than the original structure’s.In other words,the sound power of the diesel engine is decreased by one third.The optimization has achieved a notable improvement.The research shorten the period of the low-noise-design of engines and has important significance to improve the engines’ NVH performing.It also provides the basis for the design of primary load-carry structures of 90°-V type-12 cylinders engines.