| With the continuous improvement of the diesel engine’s strengthening degree,the mechanical load and thermal load that it bears have increased significantly,and the working environment is getting worse.When the diesel engine is running,the cylinder liner is not only affected by the pretension of the cylinder head bolts,the side impact force of the piston caused by the reciprocating movement of the piston,the gas pressure,but also the influence of gas combustion and uneven cooling of the coolant,and the cylinder liner is prone to irregular deformation.As a result,the engine oil is channeled into the combustion chamber to participate in the combustion,generating a large amount of particulate matter,which seriously affects emissions.Therefore,it is of great significance to study the deformation of the cylinder liner in order to reduce the oil consumption,improve the tightness of the cylinder,and improve the economy,reliability and emission performance of the diesel engine.Taking the dry cylinder liner of a non-road high-pressure common rail diesel engine as the research object,a finite element model was established,the effect of different loads on the deformation of the dry cylinder liner was systematically analyzed,and the deformation of the cylinder liner by non-structural parameters was studied based on the orthogonal design The influence of different loads on the deformation amplitude of each order of the dry cylinder liner was investigated by Fourier decomposition method.The specific research contents are as follows:(1)A body-cylinder head-cylinder liner coupling model was built,and the deformation law of the cylinder liner under preload conditions was studied through static calculations,the deformation characteristics of the third cylinder wer e extracted,and the Fourier decomposition was used to study the cylinder head bolt preload The effect of force on the deformation of cylinder liners in different orders.The research shows that under the influence of the bolt preload and interference fit,the cylinder liner gradually decreases from the top surface of the cylinder liner to the bottom of the cylinder liner,and the length of the cylinder liner exceeds the length of the cylinder bore of the machine body.,The amount of deformation at the bottom of the cylinder liner increases slightly.The maximum deformation of the cylinder liner appears in the 90° area of the upper part of the first cylinder,and the deformation amount is about 5.2μm.The minimum deformation of the cylinder liner occurs in the upper 180° area of the third cylinder,and the deformation amount is 1.8um;In the case of surplus,the non-uniformity of the comprehensive deformation of the four cylinder liners,as the cylinder liner depth increases,the deformation of the cylin der liner gradually decreases from top to bottom.The middle gradually increases toward the first cylinder and the fourth cylinder.The maximum deformation occurs in the area of 90° above the fourth cylinder with a deformation of 0.86μm;the maximum deformation occurs in the area of 180° above the third cylinder with the deformation of 0.4μm.The effect of bolt preload on the different order amplitudes of Fourier decomposition at different positions of the cylinder liner is different.Among them,the effect of bolt preload on the second-order deformation of the cylinder liner increases first as the distance from the top of the cylinder liner increases.After the reduction,in the third-order deformation,the bolt preloading force has the greatest impact on the top of the cylinder liner.As the depth increases,the amount of deformation gradually decreases;the effect of the bolt preloading force on the fourth-order deformation is similar to the third-order deformation.(2)Based on the orthogonal design method,the effects of non-structural parameters on the deformation of the cylinder liner preload and the effects of Fourier decomposition on different orders of amplitude are studied.Studies have shown that bolt preload has the greatest effect on cylinder liner deformation,cylinder liner deformation increases with bolt preload,and the impact of cylinder head stiffness and friction coefficient on each evaluation index is compared to bolt preload Not obvious,when there is a certain value,the deformation of the cylinder liner is the smallest;the bolt preloading force has the greatest influence on the second,third,and fourth order deformations.With the increase of the bolt preloading force,the deformation amplitude of each order is also Increase,but the effect of cylinder head stiffness and friction coefficient on the deformation amplitude of each order is not obvious.(3)The fluid-solid coupled heat transfer calculation method was used to study the influence of cylinder liner deformation and thermal load on the different order amplitudes of cylinder liner Fourier decomposition.Studies have shown that from the axial direction,the area farther away from the top surface of the cylinder liner is less affected by the thermal load.Among them,the deformation of one cylinder and four cylinders,two cylinders and three cylinders are distributed symmetrically in the radial direction.Through the Fourier decomposition,it is found that the thermal load has different effects on the different orders of the cylinder liner.The effect of the secondorder deformation on the cylinder liner decreases with the distance from the top of the cylinder liner;for the third-order deformation and the fourth-order deformation,Has a greater influence on the amount of deformation at the top of the cylinder liner.As the depth of the cylinder liner increases,the amount of deformation gradually decreases,and the amount of deformation at the bottom slightly increases,but the magnitude is relatively small.(4)Through the comparative analysis of the maximum expansion deformation,maximum compression deformation and Fourier decomposition of different order deformations of the cylinder liner deformation under thermal load,it is found that the thermal load has the largest influence on the first-order deformation and the secondorder deformation of the cylinder liner.The deformation and ellipse deformation are the main ones.Comparing the deformations of the cylinder liner and the Fourier decomposition under preload conditions,the second-order deformation and third-order deformation under heat load are significantly greater than those under preload conditions and the fourth-order deformation;fourth-order deformation The order of magnitude is the same,and the magnitude of the fourth-order deformation under thermal load is slightly larger than the fourth-order deformation in the preload condition;the pretension condition mainly deforms the cylinder liner eccentrically,elliptical deformation,three-lobed deformation,and four-lobed,five The deformation of the petals is mainly,and the deformation of the cylinder liner by heat load is mainly eccentric deformation and elliptical deformation.(5)Comparative analysis of the effects of different engine cylinders on the Fourier decomposition of the cylinder liner under different cylinder bursts.The deformation of the cylinder liner under the thermal engine coupling is similar to the deformation of the cylinder liner under thermal load.In the radial direction,one cylinder The deformation with the four-cylinder,second-cylinder and third-cylinder is symmetrically distributed.When different cylinders burst,the total deformation of each cylinder is not much different.The maximum deformation of the cylinder liner is located on the 270° top surface of the first cylinder and the 90° top surface of the fourth cylinder.The minimum deformation is in the second cylinder and the third cylinder.The bottom of the cylinder.When different cylinders burst,the phases of the second-order deformation of the third cylinder liner and the fourth-order deformation are basically the same as the compression deformation and expansion deformation.The effect of the first-order deformation amplitude is larger,and the influence to the fourth-order deformation amplitude is smaller. |
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