Investigation On Combustion Noise And Improved Design Based On Virtual Design Technology

Serious sound pollution bringing more attention on the conflict of power consuming and environment protection, then how to solve this difficulty becomes a focus in the world. Noise, vibration and harshness (NVH) of automotive engines is increasingly becoming an integral part of the design process along with traditional issues of durability and performance. Combined with low combustion noise analysis and improved design for X6170ZC diesel engine, the thesis points out the significance of the design of low vibration and noise with virtual design technology and the main method is discussed. This paper carried on full analysis in the principle and control methods of engine combined noise. Based on these approaches, some effective methods, that is through reducing surface vibration of engine to improve noise, were put forward.In this part of dynamic characteristics of substructure, the Finite element modal of block and crankshaft were created, then test and FE analysis had combined to hold the external vibration and radiated noise of engine. And the accuracy of FEM was validated.Aiming at the virtual design of low noise engine, this thesis applied finite element analysis and the flexible multi-body dynamics to predict the vibration and noise level. This paper carried on full analysis of the flexible multi-body dynamics, and relationship between surface vibration and radiated noise. To predict radiated noise level, the researcher made out the qualitative expression of this relationship of vibration and noise.For above analysis method, predicted the vibration and noise of X6170ZC diesel, and grasped the level respectively. Through analyzing vibration characteristics, pointed out a practical improved method of reducing vibration and noise. The further work was simulation of new design patterns. The results showed obvious reduction of sound power with no more change in other performances and little increase in production cost.Based on all of the work above, it is concluded that through structure design the combined noise could be reduced ,and the virtual design mode of diesel engine conducted in the paper is feasible and will be helpful for our country's I.C. engine industry development in future.