Coupling Characteristics of Lubrication and Flexible Multibody Dynamics of Piston-Liner Pairs in Diesel Engines

Abstract

In this paper, a new piston-liner tribo-dynamic coupling model is proposed to study the dynamics and lubrication characteristics of the piston-liner friction pair of four-stroke vehicle diesel engines. In the model, the piston-rod-crankshaft flexible multibody dynamic system is described by absolute nodal coordinate formulation (ANCF), and the lubrication behavior is described by the averaged Reynolds equation and the Greenwood-Tripp asperity contact theory. The simulation is realized based on commercial software combined with self-developed codes. The results show that the liner has a maximum transient deformation of 23.6 μm due to cylinder pressure and piston knocking behavior. Compared with the rigid model, the proposed model considering the elastic deformation increases lateral displacement of piston by 40% with oil film pressure concentration in lubrication domain. In addition, the friction power loss of flexible model in one cycle is smaller and 17.7% lower than that of rigid model.

Keywords

• piston-liner pairs
• tribo-dynamics
• flexible multibody system
• finite element method
• diesel engines