Study On Wear Failure Of Valve Oil Seal

The valve oil seal is installed on the upper end of the valve guide of the engine cylinder head,mainly to seal the valve guide rod,and its sealing performance directly affects the performance of the engine.In recent decades,the rapid development of automobile industry has put forward higher requirements for engine performance,which brings higher sealing performance requirements for valve oil seal.The traditional valve oil seal is generally designed by experience,and only when the finished product comes out,its sealing performance can be obtained through experimental detection,which leads to the extension of development cycle and the increase of cost.With the development of computer technology,simulation analysis has gradually become a new method to develop and design valve oil seal.In this paper,the two-dimensional axisymmetric model of valve seal is established in ABAQUS software,and then the influence of structural parameters of valve seal on its sealing performance is studied.The final results show that the maximum contact pressure of valve oil seal lip is positively related to the change of gas surface lip angle,and negatively related to the change of oil surface lip angle,interference,spring stiffness and lip fillet radius;the radial force per unit circumference of valve oil seal is positively related to the change of gas surface lip angle and interference,and negatively related to the change of oil surface lip angle,spring stiffness and lip fillet radius.Combined with the finite element analysis method,the structural parameters of valve oil seal are optimized by orthogonal design.The main and secondary order of the influence of the structural parameters of the oil seal on the sealing performance is obtained from the results of the extreme difference analysis;then the mean value is calculated,and the optimal structural parameters combination of valve oil seal is obtained by tak-ing the maximum contact pressure and the minimum radial force per unit circumfere-nce as the optimization objectives.In the wear analysis of oil seal,four groups of wear coefficients are measured through experiments,and then the four points are used for curve fitting.Finally,the wear coefficient is calculated when the contact pressure is 2.797 mpa.Then,the wear depth formula is deduced according to the Archard wear theory formula.Combined with the measured wear coefficient and the contact pressure obtained from the previous simulation,the wear depth of the valve stem moving up and down once is calculated.After repeated simulation experiments,the total depth of wear failure is obtained.Finally,combined with the total depth and wear depth,the wear life of valve oil seal is calculated and compared with the rated life to see whether it meets the requirements.Based on the oil seal designed by orthogonal test,combined with the calculated wear depth of each wear,The sealing performance of valve oil seal after 5 × 10 ^ 6 times,1 × 10^ 7 times,2 × 10 ^ 7 times and 4 × 10 ^ 7 times wear and tear is analyzed,and the change rule of oil seal sealing performance with wear times is studied,so as to explore the influence of oil seal wear on its sealing performance.