Flow Simulation, Based On Network Analysis Of Diesel Engine Lubrication System

Well-lubricated system of the diesel engine has the functions of lubrication, cooling, anti-rust, cleaning and others. Besides the functions above, the design of modern internal combustion engine lubrication system also need to meet the ever-increasing emission regulations, especially the regulation on the limit of diesel PM emission. Therefore, the reduction of oil consumption will inevitably become a very important aspect in the research and development of internal combustion engine.This paper took the lubrication system of four-cylinder diesel engine as research subject, analyzing the lubrication system with one-dimensional flow simulation based on the network analysis method and doing experiment on the lubrication system of diesel engine. It introduced the research method and simulation software about lubrication system, and the flux of main circuit and the temperature, pressure of the key components in lubrication system were tested with the appropriate method which the paper designed. Also the testing results were analyzed, and the one-dimensional model of CAE simulation for a four-cylinder diesel engine was established based on the actual performance of circuit size and components, simulating the lubrication condition of each part in lubrication system realistically. The model's accuracy was proved through comparing the simulation data with the testing data.Through comparing the simulation analysis with the actual testing results, the results are concluded that the design of lubrication systems for the diesel engine is reasonable, and the friction parts can be sufficiently lubricated. But there are also some places that need optimization. First of all, the pressure loss is very serious in the oil circuit of the lubrication system. At the maximum speed, the pressure loss in the oil cooler reaches to 0.052 Mpa, and the pressure loss in oil filter reaches to 0.085Mpa, while the pressure loss of the oil pump outlet to the main oil circuit even reaches 0.222Mpa. So it can be considered that the oil cooler and oil filter should be redesigned or new oil filter which can meet the Europeâ…¢emission regulations. Through comparing the minimize film thickness at maximum speed and maximum torque with the allowable film thickness given by the Technical research institute of Liszt at Austria, the surface of main bearing formed a fluid dynamic lubrication,and the engine main bearing is reliable;Thirdly, when compared with the calculation results of experience formulas, the oil quantity of cooling nozzle is a little inadequate. Through increasing the diameter of cooling nozzle orifice from 1mm to 1.05mm, the injection quantity of cooling nozzle meeting the needs of experience formulas can be achieved, guaranteeing the heat releasing balance of piston group.