内燃机仿生孔型活塞热-结构耦合特性分析

 将凹坑型结构优化变形应用于内燃机活塞-缸套摩擦副中，研究了仿生孔型活塞的热-结构耦合特性。以XL-2V 型发动机活塞为试验母体，根据标准活塞的受力分布，运用正交试验法建立了9 种仿生孔型活塞试验模型，应用传热分析第3 类边界条件和最大侧压力，对其进行了热-结构耦合有限元分析。结果表明，9 种仿生孔型活塞模型的裙部最大变形（D_max）和裙部径向变形范围（U_{x max}-U_{x min}）均小于标准活塞，其中综合性能最优的1^#仿生活塞裙部的仿生孔为凹坑型，孔径相对最小（d₁~d₄分别为1、1.5、2、2.5 mm），且均匀分布（间距1.2°）；小孔径、均匀分布的凹坑型仿生孔使活塞表面润滑油膜更均匀，同时使裙部应力卸载，从而可以有效地减少摩擦磨损，降低机械损耗，提高刚度，延长使用寿命。

Thermal-structural Coupling Analysis of Internal Combustion Engines’ Bionic Piston Skirt

In this paper, the pit non-smooth structure is used in the piston-liner system of internal combustion engines, because it has relatively little friction and wear. Pits and pores are machined on the piston skirt surface, reducing the friction and wear of the piston-liner system. In this way, the working life of the system is extended. Taking XL-2V type engine for example, the stress distribution is analyzed when the standard piston motions. Using the orthogonal experiment method, this paper has established nine types of bionic pass piston test models. Thermal-structural coupling finite-element analysis of bionic and standard pistons was carried out using the third class boundary conditions in heat transfer analysis and maximum lateral pressure. The maximum deformation and radial deformation range of piston skirts were obtained. The former affected the skirt oil film thickness and the latter affected the oil film distribution uniformity degree. Finally, the first type of bionic piston was selected, which has better performance on friction reduction and wear-resistance compared with standard pistons. The results show that the uniformly distributed pit-styled bionic pores with relatively small diameters in pistons could increase the uniformity of oil films on the surface of the piston, and at the same time reduce the stress around the skirt, thus reducing the friction and wear, reducing mechanical losses, improving stiffness, and extending the working life of pistons.