Theoretical And Application Research On The Vibration And Noise Control Of Heavy Duty Vehicle Engine

Aiming at the problem of heavy duty vehicle engine vibration and noise, this thesis develops theoretical and application research on the vibration and noise control for a 6-cylinder, in-line, four-stroke diesel engine based on modern design theory and technique.Academic and testing method is used to research the connection between engine surface vibration and radiated noise. The surface vibration velocity testing method is developed to forecast the contribution of engine main radiated noise sources to engine whole sound power and engine sound power expression. The prediction of this diesel engine main noise sources and their contribution to engine sound power is carried out accords with experiment result. Sound intensity testing is done to identify engine main radiated noise sources. The contribution of engine sound power and noise sources are calculated from sound intensity test data. It shows the destination of low noise engine design.Contributions of combustion noise and mechanical noise to engine sound power on engine different operation condition are researched by testing. The influences of speed and load to contributions of combustion noise and mechanical noise to engine sound power are revealed. This paper also introduces analytic hierarchy process (AHP) and cluster analysis into engine noise source analysis. Based on test data, contributions and weight values of noise to 1/3 octave center frequency and engine main parts to key frequency band are analyzed in engine working speed range.Dynamic characteristics of engine block and crank shaft were obtained and investigated by experiment and FEA. The results from experiment and FEA revealed the reliability of the FEA model. The result shows the cause of engine vibration and surface radiated noise. Noise energy mainly focuses on 1000～2500 Hz in 1/3 octave band. Finite element method and flexible multi-body dynamics method are used to establish engine simulation model, calculate engine vibration intensity and radiated noise.Based on the investigation of diesel engine combustion noise and mechanical noise generation mechanismmain and influencing factors, the optimal designs are carried out to decrease engine radiated noise of thin-walled part, combustion noise and mechanical noise. Without adding complexity of engine production processing, the vibration of engine test points fall of 2.0～8.8 m/s~2 and engine sound pressure level fall of 2.5 dB ( A) on rating condition and 3.88 dB ( A) on idle condition.