Research On The Influence Of Cylinder Liner Out-of-roundness Characteristics On Oil Consumption And Friction Loss

In order to meet the increasingly stringent emissions regulations,internal combustion engines are required to develop towards high-strength,high-power,high-explosive pressure,and lightweight design,resulting in out-of-roundness deformation of cylinder liners.The out-of-roundness cylinder liners can cause problems such as power loss,blow-by,and high oil consumption,which have a great impact on engine power and economy performance.Therefore,a comprehensive study of the effect of cylinder liner out-of-roundness characteristics on oil consumption and friction loss is of great significance for improving engine performance,reducing oil consumption and particulate emissions.Taking a high-pressure common rail diesel engine as the research object,the out-of-roundness deformation characteristics of the dry cylinder liner are studied by a combination of simulation and test.The simulation schemes with different cylinder liner inner surface working profiles are designed based on the comprehensive deformation,second-order deformation,third-order deformation and fourth-order deformation of the cylinder liner to study the influence of cylinder liner out-of-roundness characteristics on oil consumption and friction loss.The main results are as follows:(1)Research on the out-of-roundness deformation of cylinder liners under different loading conditionsA thermal-mechanical coupling simulation model including cylinder head bolts,cylinder head,cylinder head gasket,cylinder liner,and engine block is established,and Fourier transform method is used to study the characteristics of the liner out-of-roundness deformation in different working conditions such as thermal state,thermal & pre-tightening state.The results show that under different loading conditions,the comprehensive deformation of the third liner is smaller than that of the fourth liner by52.1%.The comparison of the out-of-roundness amplitudes between the third and fourth liner shows that the second-order amplitude of the third liner is larger by 119.7%,the third-order amplitude is lower by 55.1%,the fourth-order amplitude is smaller by 17.5%,and the fifth-order amplitude is smaller by 56.3%,the sixth-order amplitude is smaller by 24.9%,and the seventh-order amplitude is smaller by 39.1%.(2)Study on the effect of cylinder liner out-of-roundness characteristics on oil consumption,blow-by and friction loss in different oil consumption conditionsA dynamic simulation model was established to study the piston motion,ring motion,blow-by volume,oil consumption and friction loss under different cylinder liner characteristic profiles.The results show that the piston radial displacement,piston inclination,and piston knock kinetic energy under the second-order liner profile are 8.2%,9.4%,and 51.0%larger than the third-order and fourth-order profile results,respectively.The maximum blow-by volume under the second-order profile is 35.4% and35.7% smaller than those under the third-order and fourth-order profiles.The average friction loss of the ring group under the second-order profile is reduced by 1.3% compared with the third-order and fourth-order profiles.(3)Research of the influence of the structural parameters of the piston ring on the blow-by volume,oil consumption and friction loss considering the deformation of the cylinder linerOn the basis of considering the out-of-roundness deformation of the cylinder liner,the orthogonal design method was used to study the influence of piston ring radial elastic force,open clearance,and lateral clearance on blow-by volume,oil consumption and friction loss.The results show that the amount of blow-by increases with the increase of the ring gap opening,and the oil consumption increases with the increase of the radial elastic force,gap opening and lateral gap of the top ring.The friction loss increases with the radial elastic force of each ring.