Forecast Of Internal Combustion Engine Based On The Statistical Energy Analysis

With the improvement of living level, requirement for the performance of vehicle is getting higher and higher. One of the most important vehicle research aspects is to reduce the vibration, lower the noise, and more and more attention is taken to the research on this field. As a main noise source of vehicle, with the increasingly stringent limits and regulations of vehicle noise, engine's noise and vibration has become more and more critical. Noise index is an important aspect in evaluating engine's performance. The measurement and forecast of engine noise play an important part in the research of noise control. The main noise source of engine can be orientated and noise reduction project can be developed based on the measurement of noise; by the forecast of engine noise, the engine noise index can be calculated in the designing period, so the whole design and manufacture process can be controlled and adjusted, as a result the dynamic design can be realized, the cost can be reduced, the efficiency can be improve, and product can be more preponderant in the fierce competition.The main contents of this paper as follow:Fundamental theories about engine vibration and noise are summarized. On the basis of analyzing engine's structure and working principle, the origination, transfer path, influential factors and control measures of engine noise are analyzed in this paper.As the forecast of engine noise, the basic theory of Statistical Energy Analysis is introduced. In this paper based on the Statistical Energy Analysis theory, a 3D noise-vibration module of oil pan is built and analyzed. The surface displacement response and radiant noise field of oil pan are analyzed, the influence of the factors such as structure intensity and structure damp on the noise is also analyzed, aiming at improving the radiant noise of oil pan, the modal is adjusted and modified. At last the improved oil pan modal is recalculated and reanalyzed, and the modified noise field is figured out.With regard to noise testing, sound pressure and sound intensity are introduced. Taking a 6-cylinder in line engine for the testing object, according to the corresponding specification, frequency spectrum is analyzed, sound pressure is measured, sound intensity is calculated, the main source and cause are identified, the influence of speed and load on engine noise is also analyzed.