CAJ | 학술논문

为揭示活塞弹性变形对活塞二阶运动及裙部润滑特性的影响规律，基于有限元法建立活塞和缸套的结构动力学模型，耦合活塞二阶运动方程及裙部流体动力润滑模型，分析活塞弹性对活塞二阶运动和裙部润滑特性的影响。结果表明：不同曲轴转角下活塞主、次推力面的变形不同，做功行程中变形明显，而且最大变形量出现的区域随曲轴转角的变化而改变；考虑活塞弹性变形后，活塞二阶运动一般比不考虑活塞弹性变形有所增加，在压缩和做功行程中增加明显；活塞裙部的最小油膜厚度增加，而总摩擦功耗降低，做功行程中两者变化明显；油膜压力场峰值出现位置及油膜压力分布规律改变，油膜压力场峰值减小。该研究为活塞裙部型线设计及配缸间隙选择提供参考。
위게시활새탄성변형대활새이계운동급군부윤활특성적영향규률，기우유한원법건립활새화항투적결구동역학모형，우합활새이계운동방정급군부류체동력윤활모형，분석활새탄성대활새이계운동화군부윤활특성적영향。결과표명：불동곡축전각하활새주、차추력면적변형불동，주공행정중변형명현，이차최대변형량출현적구역수곡축전각적변화이개변；고필활새탄성변형후，활새이계운동일반비불고필활새탄성변형유소증가，재압축화주공행정중증가명현；활새군부적최소유막후도증가，이총마찰공모강저，주공행정중량자변화명현；유막압력장봉치출현위치급유막압력분포규률개변，유막압력장봉치감소。해연구위활새군부형선설계급배항간극선택제공삼고。
Piston skirt-liner is one of the primary friction pairs influencing the friction power loss of an internal combustion engine, so it is feasible to improve the fuel economy of engines by studying the lubrication characteristics of the piston skirt-liner to reduce the friction power loss. The piston skirt lubrication is related to the piston secondary motion and the elastic deformation of the piston and liner, and there exists a strong coupled relationship between them. Therefore, it may be more reasonable to couple the elastic deformation equation of piston and liner than ignore the deformation of piston and liner, when the piston skirt lubrication and the piston secondary motion equations are solved. In order to reveal the effects of the piston elastic deformation on the piston secondary motion and skirt lubrication characteristics, the structural dynamics equations of the piston and liner were established based on the finite element modal reduction method, the piston secondary motion equation, the average Reynolds equation and the possible solid-to-solid contact equation in mixed lubrication were solved iteratively based on the parameters of a single-cylinder diesel engine, and the difference between the skirt lubrication performances with or without considering the elastic deformations of piston was analyzed. The results showed that the elastic deformation configurations of the piston skirt thrust and anti-thrust sides experienced different variations with crank angles and the deformation was significant at work stroke. Besides, the maximum deformation region of the piston skirt side was variable at different crank angles, sometimes in the middle of the piston skirt side, and sometimes at the bottom edges of the piston skirt side. It could be found that the piston secondary motion quantities including the piston deformation became bigger, when compared with those excluding the deformation of piston, especially at compress and work strokes. The eccentricity of piston at the bottom of the skirt including the piston deformation was about 1.3 times as big as those excluding the piston deformation in the region from 370 to 500°CAat work stroke. The minimum film thickness was increased at intake, compress and work strokes, with fluctuating at exhaust stroke and significant changes at work stroke. Furthermore, the minimum film thickness considering the deformation of piston were about 2 times as big as those excluding the deformation of piston at work stroke. While the total friction power loss was reduced significantly and was about 0.4 times as big as those excluding the deformation of piston at work stroke,and varied slightly at other strokes. Also, the configurations of the oil film pressure field experienced different variations with crank angles, from parabolic to saddle-shaped ones, when the deformation of piston was not considered and considered. The peak values of oil film pressure field became smaller and were about 0.5 times as big as those excluding the deformation of piston at intake, compress and work strokes. It is necessary to consider the effect of the piston deformation in order to obtain reliable solutions when the piston skirt lubrication is investigated.