Research On Improvement Design For Structure Of CA6110 Diesel Engine Reducing Noise And Vibration

CA6110 series diesel engine provided mainly for medium and heavy Jiefang trucks of FAW ,were designed by FAW Jiefang automobile co. , ltd. Dalian branch, imitating the same model of Japan. The holistic vibration and noise of the diesel engines were not controlled effectively during the process of product design for the objective of survey design and lack of necessary dynamic experiment devices and perfect testing ways.Finite element method (FEM) is widely used in structural analysis, elastic mechanics and so on. In the paper the discussion about FEM focuses on elastic mechanics.The solutions of elastic mechanics problem are of two kinds, analytic solution and numerical solution.It can be express as: analytic solution differential equationThe solutions of elastic numerical solution-- mechanics problem numerical solution finitedifferencemethod discrete model numericalsolution--FEM ANSYS PROGRAM is a powerful FEM analysis software. The field, which it can be applied in, has expanded from plane problem to 3D problem, from structural stress analysis to structural optimize, from static balance to dynamic stability.The reason why ANSYS is so powerful is that it has many great modules. A structure model in ANSYS is show in Fig1-2Modal analysis is used to validate the results form ANSYS. The modal analysis, based on the vibration theory, is a subject that studies the relationship between system physical parameter and mode parameter, and then confirms these parameters in some way. In general, the structure modal analysis means the vibration analysisIn the structure model analysis, there is an essential different between MDOF (multi degree of freedom) system and SDOF (single degree of freedom) system. For a DOF system, there are independent physical coordinates to describe the system. If the system is linear, the responses can be express as a superposition of the system modes. Every system model has a corresponding frequency. For a linear viscous system, there is also corresponding damp. In general, a DOF system has frequencies and modes, while single DOF system only has one frequency.This text built the FEA analysis model about the cylinder block and oil pan at first, and it proved that the FEA model was rational by using the analysis way of experiment model. Then the drawback of the structure of the primary cylinder block and oil pan was found based on FEA analysis model and experiment model, and improved by adding the board and tendon structure on the cylinder block. According to the improved way, it also do the contrast experiments between the inherent frequency model and the speed response model, and do the experiment about the noise in an anechoic chamber. It proved that the improved way really reduced the vibration and noise.Contrast of sound pressure of several test points is shown. Top curve is for the former machine; bottom curve is for the improved one. Sound pressure level's comparition of old oil pan and oil pan of sandwich material on diesel end.The testing result and the theoretical analysis of this text provided the valuable proof for reducing the vibration and noise of the same kind of diesel engines by improving the structure of various parts.