The Temperature Filed' Influence On The Lubrication State Of A High Speed Gasoline Engine Main Bearing

As one of the most important power machinery, internal combustion engine is a complex friction system in which the t ribology and wear is the most important factors restricting the mechanical efficiency of the machine. In internal combustion engine, radical sliding bearings were widely used, whose friction loss is an important part of the mechanical loss. With the developing towards high speed and big power of the internal combustion engine, the relatively speed between the bearings and the journals becomes higher and higher, resulting much more power loss and making heat resulting from the friction loss become much more. The heat and thermal deformation has a great influence on the lubrication of the bearing, so in order to analyze the lubrication problem more accurately, the thermal deformation problem should be taken into serious consideration, traditionally and most of time, by means of thermo-elastohydro-dynamic(short for TEHD) analysis.In this paper, a new method was used to analyze the lubrication problem of main bearing regarding the thermal effect. Based on an In-Line four-cylinder high-speed gasoline engine, a thermo-elasto-hydro-dynamic analysis on the main bearing was done under all kinds of conditions with Reynolds Equation firstly. Then, with the Non-Stationary heat transfer problem and the thermal condition of the block taken into consideration, the temperature field and thermal deformation of the third main bearing were got by iterations, and after putting the temperature field and thermal deformation into its heat boundary condition, the lubrication problem of the third main bearing was analyzed emphatically.Finally conclusions were got by comparison. Compare with the tribology and wear of the bearing when disregarding the Non-Stationary heat transfer, when the Non-Stationary heat transfer was taking into account, the wear of the main bearing becomes much more severe, and has a more conformity with the bearing situation in the bench test. So the method used in this paper has a more accuracy to analyze the main bearing' lubrication problem compare to the TEHD analysis, and will be helpful and meaningful in the process of the design and optimization of the main bearing.