Modeling of piston pin rotation in a large bore gas engine

Abstract

<div class="section abstract"><div class="htmlview paragraph">In an engine system, the piston pin is subjected to high loading and severe lubrication conditions, and pin seizures still occur during new engine development. A better understanding of the lubricating oil behavior and the dynamics of the piston pin could lead to cost- effective solutions to mitigate these problems. However, research in this area is still limited due to the complexity of the lubrication and the pin dynamics.</div><div class="htmlview paragraph">In this work, a numerical model that considers structure deformation and oil cavitation was developed to investigate the lubrication and dynamics of the piston pin. The model combines multi-body dynamics and elasto-hydrodynamic lubrication. A routine was established for generating and processing compliance matrices and further optimized to reduce computation time and improve the convergence of the equations. A simple built-in wear model was used to modify the pin bore and small end profiles based on the asperity contact pressures. The model was then applied to a large bore gas engine, and simulations of the pin’s rotation and frictional forces were carried out under various operating conditions.</div><div class="htmlview paragraph">The pin’s rotation is determined by the frictional forces of the small end and pin bores, and is the result of the collaborative action of boundary friction and shear stress of the oil film. The simulation results indicate that hydrodynamic lubrication is dominant in supporting the normal load and there is a predominant direction of the piston pin rotation and the angular speed is closely related to the operating conditions. Experimental results have been compared to the simulation, demonstrating the model’s reliability and accuracy.</div></div>