Research On Deformation Of Dry Cylinder Liner Of Non-road High Pressure Common Rail Diesel Engine

Non-road diesel engine due to poor working conditions,dramatic changes in operating conditions,heavy load,power range,the reliability of the diesel engine,acceleration and economy should be higher requirements.With the implementation of non-road country three emission standards,diesel engine to enhance the degree of continuous improvement,making direct contact with the gas parts of the thermal load and mechanical load is getting higher and higher.Non-road diesel engine due to low speed,coolant fluidity is poor,uneven temperature distribution increases,resulting in cylinder,piston and cylinder head and other heating parts heat load is more harsh.Cylinder liner is a thin-walled parts,the irregular round will lead to piston ring-cylinder liner friction wear,oil fleeing into the combustion chamber increased,channeling gas increased,and then lead to increased oil consumption,diesel engine power reduction,Particle emissions worse.In addition,the cylinder liner rounded to increase the piston side pendulum,increasing the engine vibration and noise.Therefore,it is very important to improve the sealing performance of the cylinder liner-piston friction pair and reduce the discharge of the particles caused by the non-road diesel engine liner.In this paper,the non-road four-valve high-pressure common-rail diesel engine is used as the research object,and the coupling model of the whole machine is established.On the basis of the cylinder head and cylinder temperature test,the diesel engine thin-walled dry cylinder is pre-installed,The temperature of the cylinder under the deformation of the law,the specific results are as follows:Firstly,according to the dynamic calculation model of the crank link mechanism,the deformation of the cylinder under the mechanical load under the rated working condition is simulated.Diesel engine cylinder under the action of the pre-tightening of the larger area of the first cylinder of the 270° direction and the fourth cylinder 90 ° direction,the maximum deformation of 10.14?m,the largest deformation occurs in the fourth cylinder 90 ° direction The The radial deformation of the cylinder liner increases about 5?m with the increase of the piston side impact force and the burst pressure on the basis of the bolt preload.The axial deformation trend is similar to that of the preload tightening,For the obvious "spoon" shape.Secondly,the temperature field and thermal deformation of the cylinder liner were calculated by using the conjugate heat transfer method through the bench test and empirical formula.The results show that the temperature of the cylinder liner is obviously high,and the deformation of the cylinder liner increases sharply to 304?m under the temperature load.The maximum deformation occurs in the 90° direction of the fourth cylinder liner The From the radial deformation of each cylinder,each cylinder liner presents a "heart" type structure.From the axial deformation of the cylinder liner,the cylinder liner will appear at both ends to narrow the middle of the protruding "barrel"-like deformation.Thirdly,the simulation calculation of diesel engine cylinder liner under various load is carried out.The deformation of each cylinder liner is calculated when the four cylinders are respectively explored.The radial and axial deformation of each cylinder liner are analyzed in detail.It is found that the deformation of the cylinder liner is reduced by about 10%compared with the thermal deformation of the cylinder liner.From the four cylinders were broken when the radial deformation of the cylinder compared to the curve,the deformation of the larger cross-section are the first cylinder liner 270 ° direction and the fourth cylinder 90° direction and are relative to The expansion of the base circle deformation,the first cylinder liner 90 ° direction and the fourth cylinder liner 27° direction there is a large compression deformation.The deformation of the second cylinder liner and the third cylinder liner in each section is smaller than that of the other two cylinders.Each section of the cylinder liner deformation are basically along the 0 °to 180 ° two lines were symmetrical connection.From the axial deformation curve of the cylinder cylinder sets in the 0 °and 180° direction of the first increase in the amount of deformation,to about 20mm from the top of the cylinder liner to reach the maximum deformation and then gradually reduced until the minimum deformation of the minimum liner The 90 ° and 270 ° direction of the four cylinder liner deformation was the opposite trend.0 ° and 180 ° direction of the first cylinder deformation is always the smallest,90 ° and 270 °in both directions the amount of deformation of the cylinder liner and the distance from the top of the cylinder liner basically linearly reduced relationship.Finally,one of the cylinder liners is used to compare the bolt preload,mechanical load,temperature load and coupling load.The thermal deformation curve and the coupling deformation curve are similar,and the different thrusts of the main thrust side Compared to 2%-10%of the thermal deformation,the coupling deformation of the cylinder thrust is opposite.Pre-deformation and mechanical deformation curve is more similar to the value of the mechanical deformation than the pre-deformation deformation of 2-5?m.Thermal deformation of the maximum mechanical deformation of about 30 times,the temperature load for the diesel engine cylinder deformation play a leading role.