活塞结构参数对敲击能量影响的计算研究

Numerical Study on Influence of Piston Structural Parameters on Piston Striking Energy

针对内燃机降噪的现实需求,以Ricardo-Pisdyn软件为模拟计算工具,综合考虑活塞接触面粗糙度、活塞和缸套热及弹性变形,建立活塞组件的三维动力学模型,系统性研究了配缸间隙、活塞销偏置以及裙部型线等结构参数对活塞敲击能量的影响规律。结果表明:配缸间隙对活塞敲击能量有明显影响,增大配缸间隙会加剧活塞二阶运动,大幅增加活塞敲击能量;活塞销向主推力面合理偏置,可减小活塞最大敲击能量;增大中凸点高度,可以缩小裙部顶端至中凸点区域与缸套的热态间隙,抑制活塞二阶运动,减小敲击能量;增大裙部顶端间隙或减小裙部型线上指数,都会引起做功行程初期活塞的剧烈敲击;裙部底端间隙和型线下指数对活塞敲击能量的影响较小,增大裙部底端间隙或者减小裙部型线下指数,会导致活塞敲击能量略微增大。

In order to meet the actual demand of noise reduction of internal combustion engine,the three-dimensional dynamic model of piston assembly was established based on the Ricardo-Pisdyn software taking into account the surface roughness,thermal and elastic deformation of piston and cylinder liner. The influence of structure parameters,such as cylinder clearance,piston-pin offset and skirt profile,on the piston striking energy is systematically studied. The results showed that the cylinder clearance gap has a significant impact on the piston striking energy. Increasing the cylinder gap increases the piston secondary motion and greatly increases the piston striking energy. The piston-pin offset to the thrust surface can reduce the maximum piston striking energy. Increasing the height of bump can reduce the clearance between skirt top to bump and cylinder,inhibit the piston secondary motion,and reduce the piston striking energy. Increasing the skirt top clearance or reducing the skirt profile top index will cause sharp knock in the beginning of power stroke. The little influence of skirt bottom clearance and skirt profile bottom index on the piston striking energy is shown. Increasing the skirt bottom clearance or decreasing the skirt profile bottom index will cause a slightly increase in the piston striking energy.