In order to reduce wear in gudgeon pin, bush and piston boss lubrication is done. Oil used in national engine
species was 10W40 with dynamic viscosity 5.5 mPa.s at 140 °C (the working temperature). In order to
complete investigation the oil film hydrodynamics analysis in small end of connecting rod, a real full model
engine with four cylinders has been simulated by AVL EXCITE5.1 software. In this software, effect of 6
variables consist of oil temperature, kind of intake, kind of fuel, tolerance bearings between gudgeon pin
and bronze bush, position of bearing and engine speed on maximum pressure and minimum thickness of
film were investigated, and each curves of them has been extracted. The effect of six inputs (oil temperature,
intake type, fuel type, tolerance, bearing position, and engine rotation speed) on the lubrication parameters
was simulated for four different modes of national engine EF7 by neural networks.
The results of AVL EXCITE simulation show that Maximum hydrodynamics pressure of oil film occurs
at 3500 rpm in 372° crank angle (combustion moment) in turbocharged engine EF7 with CNG fuel was 446
MPa and 1.83 μm respectively at 140°C working temperature of oil. At same condition, minimum hydrodynamics
of oil thickness was 1.83 μm, which bearing wear was the possibility. The best neural network FFBP
topology for the prediction lubrication parameters (maximum pressure and minimum thickness) was 6-24-
30-2 structure with learning algorithm trainlm and functions threshold logsig, tansig and is pureline.