Agricultural Tractor Engine Noise Prediction and Optimization through Test and Simulation Techniques

Engine radiated noise has complex behavior as engine assembly consist different components, varying dynamic forces with wide range of speed. For open station tractor, engine noise is major contributor and hence needs to be optimized for regulatory norms as well customer comfort. The awareness about NVH comfort in domestic market as well as export market is increasing as customer have become more demanding. This forces OEM’s to put serious efforts to ensure the OEL noise / Engine noise is at acceptable levels. Identifying the optimized countermeasures to reduce the engine noise during the early design phase has a greater impact in reducing product development time and cost. This paper describes about a process that has been established for evaluating engine radiated noise and to improve the overall NVH performance. This virtual engine analysis has been carried out with commercially available FE software and identified dominant noise contributing components to target the noise reduction at engine level. The engine forces are predicted with engine input data in commercially available software. These forces are applied to the Engine assembly FE model at the strategic locations on engine to predict the surface vibrations at the component faces and engine 1-m noise. The surface vibration and 1-m noise plots are analyzed and correlated with test data and modal analysis results. Top 5 engine components like front cover, crank pulley, oil sump etc. were identified towards potential contributors of engine noise. The modifications are suggested for each engine component to reduce noise radiated and meet targeted noise. The engine development project requirement focused heavily on weight reduction and hence optimization was carried out to improve the surface vibrations and noise. The suggested counter measures were analyzed and validated to reduce engine noise. It has been observed that the counter measures developed with the process described above helped in improving the noise levels of 3 dB(A).