Indian Journal of Science and Technology

Abstract

Background/Objectives: The effects of hydrodynamic and boundary lubrication occurring in the plunger-bushing friction pair of the high-pressure fuel injection pump in marine combustion engines have been studied. Methods: To determine thickness of the boundary lubrication layer of fuel, optical double refraction method has been suggested based on the optical anisotropy phenomenon. As an evaluation of tribotechnical characteristics of the plunger-fuel-bushing triad the electric impulse wear measuring technique has been suggested enabling to determine friction force and wear intensity. Findings: It has been proven that the fuel located in the gap between the plunger ram and the bushing performs lubricating functions. It has been shown that, owing to the elastic and damping properties and the disjoining pressure, the boundary layer of fuel helps reducing friction loss and wear of the contacting surfaces. The thickness of the fuel boundary layer affected by two-phase pressure of plane-parallel metallic surfaces has been determined. Marine fuels with viscosity value of 380…500 sSt at 40оС were used for the experiments; investigations were carried out in the temperature range of 30… 60оС. It has been experimentally established that the thickness of the fuel boundary layer ranges within 4…12 micrometer, depending on operational conditions, which enables hydrodynamic and boundary (preventing direct contact between the surfaces) modes of lubrication. The ways for improving regularity of molecules in the boundary layer and for controlling its thickness have been suggested. Applications/Improvements: Liquid-crystalline properties of the boundary layers of fuel can be used in the precision pairs of high-pressure fuel injection pumps to reduce mechanical losses and to improve fuel efficiency.

Keywords: Bushing, High-pressure Fuel Injection Pump, Hydrodynamic and Boundary Lubrication, Marine Combustion Engine, Plunger Ram, Wear Intensity