Research On Lubrication Performance Of Piston Ring-cylinder Liner Considering The Cylinder Liner Deformation

With the improvement of the strengthen degree in the internal combustion engine,the deformation of cylinder liner will be increased much more.It will not only cause the leakage of oil,but also lead to the boundary lubrication partly of the piston ring-cylinder liner pairs and worse friction and wear.The failure of the pairs could affect the normal work of engine.Under this background,for a V12 diesel engine,my thesis deeply do some research of the lubrication performance of piston ring-cylinder liner considering the liner deformation.Hence the main contents in this research are shown as follows:(1)Based on the basic principle of hydrodynamic,the mathematical models of the lubrication performance of piston ring-cylinder liner under ideal cylinder liner were established by combining the gas leakage equqtion,Reynolds equation and force equilibrium equations.We proposed the finite-difference method to finish the calculation and got the performance of maximum film pressure,minimum film thickness,friction and power loses.(2)Finished the analysis of cylinder liner deformation under the pretightening condition based on the FEM.Realized the evaluation indexes of cylinder liner deformation of out-of-roundness and Fourier spectrum analysis by Matlab programming,then compared with test results.Finally we got the deformation performance of cylinder liner transversal surfaces.(3)Aimed at the deformation of piston ring and the distribution of oil film under the deformed cylinder liner,the data of liner deformation was applied to the calculation of the film thickness in the beginning.The piston ring was spread to be a piston ring beam and discretized.The mathematical models of the piston ring beam deformation were established under composite forces.Finally we finished the calculation with the method of dynamic equilibrium iteration by assuming litter external loads and analysed the deformation form of piston ring and lubrication performance of piston ring-cylinder liner under the deformed cylinder liner.