Research On Anti-wear Design Methods For Inner Wall Of Cylinder Head Of Small Aviation Piston Engine

Aviation piston engine piston / cylinder head inner wall friction,piston ring / cylinder head inner wall friction is the most important and most critical movement friction pairs inside the engine.As the user's requirements for engine operation and fuel requirements increase,the working environment of the piston/cylinder head inner wall friction pair and the piston ring/cylinder head inner wall friction pair becomes more severe,and the working load conditions are more severe.The piston and the inner wall of the cylinder head are subjected to high thermal and mechanical loads,At the same time,the lubrication condition of the friction pair deteriorates at high temperature,causing the friction and wear of the friction pair to be intensified,and even directly causing the friction pair to fail.In this paper,the anti-wear design method of the inner wall of small aviation piston engine cylinder head is studied.Firstly,starting from the working load condition of the inner wall of the cylinder head during the working process of the engine,the thermal load received during the working process of the cylinder head,the force of the piston skirt and the piston ring on the inner wall of the cylinder head are analyzed,and the working load condition of the inner wall of the cylinder head is obtained.Research indicates that the inner wall temperature range of the piston reciprocating stroke area is [365K,455K] and the maximum lateral pressure of the piston skirt to the cylinder wall is 0.7MPa and the contact pressure of the piston ring to the cylinder wall is 0.33 MPa.Then,according to the working contact characteristics and material characteristics of the piston / cylinder head inner wall friction pair and the piston ring / cylinder head inner wall friction pair,the surface contact friction pair simulating the friction pair of the piston/cylinder head inner wall and the line contact friction pair simulating the friction ring of the piston ring / cylinder head inner wall is designed respectively.The influence of load conditions on the friction and wear properties of friction pairs was studied by means of the test machine simulating the reciprocating motion of the friction pair.Research indicates that the increase of the temperature leads to an increase in the friction coefficient,and the increase of the sliding frequency and the normal load leads to a decrease in the friction coefficient,the law of wear amount is not obvious under different load conditions.However,when the test temperature of the surface contact friction pair is 225 °C,the wear of the cylinder wall simulation part is the largest,the maximum wear amount is 1.7mg,and the corresponding piston simulation part wear amount is 1.1mg;When the normal contact force of the line contact friction pair test is 22 N,the wear of the cylinder wall simulation part is the largest,and the maximum wear amount is 1.1mg.The corresponding wear of the piston ring analog parts is unmeasurable.Finally,the anti-wear coating is designed on the surface of the simulated part,and the wear resistance of the coating is studied under the condition of maximum wear,and obtain the coating with excellent anti-wear performance.After the surface of the simulated part is coated,the wear of the hard anodized coating cylinder wall in the surface contact friction pair is 0.3 mg under the test conditions of 225 °C,which is reduced compared with the uncoated part.82%,the piston simulation part wear amount is 0.7mg,which is 36% lower than that of the uncoated part,and the surface temperature of the hard anodized coating is 13°C lower than that of the uncoated part.Besides,The wear of the hard anodized coating cylinder wall in the line contact friction pair is 0.5mg under normal load 22 N test conditions,which is 55% lower than that of the uncoated part,but the wear of the piston ring is increased,and the wear amount is 0.4mg.In general,the hard anodized coating has excellent wear resistance,and can significantly improve the wear resistance of the cylinder wall and the piston,and can be used as an anti-wear coating for the piston skirt and the inner wall of the cylinder head.In this paper,through the simulation analysis and experimental research methods,the working load conditions of the inner wall of cylinder head were studied.The wear test of the cylinder wall simulation parts was carried out,and the influence of load conditions on the friction and wear characteristics was obtained.The anti-wear coating was designed and the anti-wear performance test of the coating was carried out,and the coating with excellent anti-wear performance was obtained,which provides theoretical guidance for the application of the next coating on the piston skirt and the inner wall of the cylinder head.