Research On Sealing Performance Optimization Of A Small Supercharged Direct Injection Gasoline Engine

The in-cylinder gas pressure and thermal load of turbocharged direct injection gasoline engine are much higher than that of natural aspiration engine,so the sealing performance of its cylinder head gasket(CHG)is required to be much higher.Usually,the failure problems caused by insufficient pressure on the CHG or excessive head lift can be well identified and evaluated in the pre-design stage according to the simulation experience,but for the relative lateral slip of the cylinder head and block caused by large thermal deformation and high gas pressure,which leads to the wear and oil leakage of the CHG,there is no good evaluation standard at this stage,which leads to the sealing problems in the later test verification.Therefore,the research of cylinder gasket seal has important practical value.This paper takes the CHG of a 1.0L 3-cylinder turbocharged direct injection gasoline engine as the object of study.On the basis of completing the design,the dynamic working conditions of thermal shock test are simulated.Combining with the factors affecting fretting wear of the cylinder gasket,the structure of the cylinder gasket is optimized to redistribute the force of the cylinder gasket,and the problem of oil leakage from the wear of the cylinder gasket is successfullyThis paper mainly completes the following work:1)Based on the performance parameters and structural characteristics of the small highstrengthened engine,the design of the CHG is completed,and the design parameters are tested.The surface pressure test and the pressure deflection curve of the CHG meet the static design requirements.2)Based on CFD cylinder gas boundary,cooling water jacket boundary and other empirical thermal boundary,the steady-state temperature field simulation of rated condition is completed,and the calibration simulation model is carried out through temperature field test to evaluate the sealing performance of cylinder gasket under rated condition.The results show that the deviation between temperature simulation and test is less than 10%,and the sealing performance of CHG meets the design requirements under the rated condition.3)Through the thermal shock test to verify the CHG,found that the CHG wear and oil leakage.Through the analysis of test phenomena and influencing parameters,it is found that during the period of transition from idle condition to rated condition,the in-cylinder gas pressure is the largest,and the thermal deformation of cylinder head and block caused by temperature alternation is the most severe condition of CHG sealing system.4)To simulate the temperature field under the dynamic condition of thermal shock test,and to evaluate the cylinder gasket seal under the influence of dynamic condition.It is found that under the most severe working conditions of the CHG sealing system,the abnormal area is consistent with the test failure location,and there is no abnormal failure area in other working conditions.By optimizing the design of cylinder gasket stopper and full bead,the problem of wear and oil leakage is solved.