Design And Study Of Ic Engine Piston Skirt Profile Based On Fem

As the development of modern industry and society, the internal combustion engine(IC engine) performance is increasingly demanding. Piston skirt profile is critical in improving engine performance, for the reason that it affects the matching gap between piston and cylinder and the formation and maintenance of dynamic lubricating oil film. Currently, there is no clear theoretical basis and effective means for piston skirt surface design which influenced by cylinder matching gap and thermal-deformation and so on factors. The unreasonable design of skirt profile curve will result in worse dynamic lubrication condition between the piston and cylinder and serious attrition of piston skirt outer surface and cylinder hole wall, even cylinder stuck, hauling, knocking and so on phenomenon. Therefore, it is of great significance to research on the piston skirt profile design and to find an advanced reasonable piston skirt surface design method.This article researches on the finite element analysis (FEA) technology of piston thermal-deformation and the problem of piston skirt profile design, proposing an IC engine piston skirt surface design and optimization method and model based on FEA. At the same time, by using the above method and model, the specific analysis, design and optimization is carried out on a 476Q automobile engine piston skirt profile of an industry group in Chongqing city, and the results are verified experimentally and tested by practice. Conclusions and research results are as follows:â‘ The specific method and technique of piston thermal-deformation FEA and skirt profile design and optimization is discussed in detail, and then the method and model of IC engine piston skirt profile design and optimization based on FEA is obtained. By simulating piston temperature field and computing its thermal-deformation with FEM, the parameters of piston skirt surface are designed and optimized based on quantitative analysis of the piston skirt thermal-deformation.â‘¡Aiming 476Q automobile engine piston, with the above piston skirt surface design and optimization method and model as a guide, three-dimensional entity model of this piston is created through the Pro/E software, and by applying ANSYS software, the piston temperature field is simulated, with its thermal-deformation being calculated then. According to the quantitative analysis of the piston skirt thermal-deformation and engine cylinder matching gap, the 476Q piston skirt is designed and optimized with the oval convex profile being obtained. The running experiment and production result indicates that the piston skirt surface design is reasonable and the engine performance is good; after 200 hours of work, the skirt outer surface is smooth with no obvious abrasion and wear happening. The design result has been used for mass production processing.â‘¢By approach of example design with experimental verification and application in practice, the IC engine piston skirt profile design and optimization method and model based on FEA is demonstrated. The results show that: 1)the method and model is reasonable, feasible, practical and effective, and could be better applied to engineering design practice; 2)It assumes that the thermal piston skirt surface as a straight circular and the piston center coincide with the cylinder hole center at work, and only taking the thermal-deformation and cylinder matching gap into account, the results showed that those assumptions and simplifications are acceptable for 476Q piston, which has a guiding role on the design of IC engine piston skirt profile.