Numerical Simulation of Lubrication Film in Piston Ring of Fuel Dispenser Flowmeter Based on Hydrodynamic Lubrication

Hydrodynamic lubrication is an ideal state of lubrication in that friction and wear hardly occur. The friction pair of piston ring-cylinder liner is one of the most important friction pairs in a flowmeter. With the development of flowmeter aiming at high-precision and high-stability, how to make the piston ring-cylinder liner system maintain a good lubrication condition has great importance in terms of reducing the friction and wear. In this paper, a hydrodynamic lubrication mathematical model on the surface of piston ring was established. And the finite difference method(FDM) and successive over relaxation method(SOR) were adopted to solve the mathematical model numerically. The dimensionless average pressure of the lubrication film was taken as the criterion to estimate the hydrodynamic lubrication performance of the piston ring, and the effects of different flow rate conditions, different fluid viscosities and different minimum film thicknesses on the lubrication film pressure distribution were investigated respectively. The numerical analysis results reveal that: (a) the average pressure decreases with the increase of minimum film thickness, under the condition of the same minimum film thickness, when the medium is diesel, the average pressure is greater than the average pressure when the medium is gasoline; (b) the lubrication film pressure increases with the increase of flow rate, and the flow regime of the lubrication film changes with the change of flow rate; (c) as the viscosity increases, the pressure increases as well, for the same leakage clearance, the higher the viscosity, the larger load-carrying capacity of the clearance lubrication film. These results provide a guidance for lubrication design of piston ring-cylinder liner friction pair.