Study And Optimizeon The Lubrication Performances Of Main Crankshaft Bearings Of A 16V Marine Diesel Engine

Crankshaft main bearing is the key component of internal combustion engine,which is used to support the movement of crank and connecting rod mechanism to achieve energy conversion and output,Therefore,it is of great significance to study the lubrication performance of the main bearing of the crankshaft for reducing the friction loss of the engine,improving the mechanical efficiency,increasing the reliability of the machine and prolonging the service life.In this paper,based on the fluid lubrication theory,a numerical model of hydrodynamic lubrication for crankshaft main bearing is established based on the averaged Reynolds equation.The lubrication parameters such as maximum oil film pressure,minimum oil film thickness,shaft orbit and friction power consumption of main bearings under different speed conditions are calculated.The analysis shows that under the rated speed condition,the external load of the five main bearings is the largest,the oil film thickness is the thinnest and the lubrication condition is the worst.On this basis,the elastohydrodynamic lubrication model of the main bearing of the crankshaft is established by considering the elastic deformation of the lubricating surface.In this model,the parameters such as oil groove,oil hole,surface roughness and so on,the lubrication performance of the main bearing,such as the inlet pressure,the flow rate,the oil filling rate and the viscosity and pressure effect of the lubricating oil,are taken into account.The lubrication parameters such as the maximum contact pressure and the oil flow rate of the main bearing are obtained.The calculation results show that the thickness of the fifth main bearings is thinner and the probability of wear is greatest when considering the elastic deformation of the lubrication surface.and the wear location coincides with the actual wear location of the bearing.Based on the calculation results above,a multi-objective optimization model is established in this paper based on the particle swarm algorithm.The optimization variables include main bearing clearance,bearing width,bearing surface roughness,oil groove width and length,etc.The optimization goal is the total friction loss of the crankshaft main bearing and the minimum total oil flow.5000 sets of experimental sample points were generated by the super-Latin algorithm,and the simulation calculations were performed to obtain the final optimization plan.The comparison shows that the total friction loss and the total oil flow of the optimized crankshaft main bearing decreased by 18.68% and by 33.57% respectively;the fifth main bearing minimum oil film thickness increased to 400%,the maximum oil film contact pressure decreased by 54.71%,The lubrication performance of the crankshaft main bearing has been effectively improved.The research work in this paper provides a reference for the analysis and optimization of the lubrication performance of the engine crankshaft main bearing.