Numerical Study of Power Loss and Lubrication of Connecting Rod Big-End

Abbas Razavykia,Paolo Baldissera,Cristiana Delprete

doi:10.3390/lubricants7060047

Abbas Razavykia, Paolo Baldissera + Show 1 more

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https://doi.org/10.3390/lubricants7060047

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Abstract

A hydrodynamic lubrication analysis for connecting rod big-end bearing is conducted. The effects of engine speed, operating condition, lubricant viscosity and oil temperature on tribological performance of big-end bearing have been examined. Force equilibrium is solved to define instantaneous eccentricity between journal and bearing to have accurate estimation of oil film thickness at interface of connecting rod big-end bearing and crankpin. Connecting rod big-end is treated as π film hydrodynamic journal bearing and finite difference scheme is applied to calculate generated hydrodynamic pressure and frictional power loss at each crank angle. Beside the development of analytical formulation, well-known Mobility model introduced by Booker has been employed to be compared with the analytical model. The presented analytical model reduces the complexity and the numerical effort with respect to Mobility method, thus shortening the computation time. The simulation results show good agreement between analytical model, Mobility approach and experimental data.

Highlights

The primary purpose of hydrodynamic bearings is to support a rotating shaft and to guaranty the hydrodynamic lubrication at bearing surfaces interface
Generated hydrodynamic pressure at connecting rod big-end and crankpin is illustrated by Figure 6 shows instantaneous net load, W, acting on the crankpin which is contributed by gas pressure and inertial imbalances due to reciprocating and rotating masses
As hydrodynamic lubrication is considered at lubricated surfaces interface, friction loss is directly proportional to engine spin speed, oil viscosity and inlet oil temperature

Summary

Introduction

The primary purpose of hydrodynamic bearings is to support a rotating shaft and to guaranty the hydrodynamic lubrication at bearing surfaces interface. Journal bearings are one of the most common types of hydrodynamic bearing. They can be found in various subsystems of reciprocating engines and powertrains. Journal bearings are designed to operate under hydrodynamic lubrication. This is under influence of applied load and relative motion of bearing components that create hydrodynamic wedge and hydrodynamic pressure within the oil film to stand against the applied load. The magnitude of the hydrodynamic pressure at journal/bearing interface is influenced by the film thickness in which the amount of available oil is a function of initial clearance and instantaneous eccentricity between centres of the lubricated pairs [1,2,3]

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