The Research On The Life Prediction Of Piston Ring Sealing Materials For Stirling Engine

During the Stirling engine operation, especially in high temperature, high pressure, heavy load and oil free lubricated conditions, the piston rings were seriously worn, resulting in the life of the piston rings cannot reach the requirement of wide application of the Sterling engine. Therefore, the purpose of this paper is to develop a kind of excellent sealing material through a series of experimental studies to solve the life of piston rings problem.Firstly, this paper analyzes a number of factors that affect the sealing performance of piston ring, such as the structural dimensions of piston rings, and manufacturing quality of the cylinder mirror when contacted, manufacturing quality and performance of the piston ring contact surface and the sealing materials, etc., and further analysis of the effects of causes and solutions way.Secondly, we studied the key factors of the sealing performance--sealing material, two different nanoparticles and two kinds of polymers reinforced PEEK/PTFE composites were prepared by mechanical blending-molding-sintering methods. The tribological and wear properties of the composites were studied with a MRH-3block-on ring friction and wear tester, and the worn surface and the mating surface microstructure were obtained by scanning electrical microscope. Using a WDW microcomputer controlled electronic material testing machine to analysis the tensile and compression mechanical performance. The results show that the anti-wear performance of10%PEEK/PTFE is320times better than pure PTFE. With the addition of nanoparticles, nano-SiO2reinforced composites show the better anti-wear performance compared with the composite filled with nano-Al2O3. In the meanwhile, the friction coefficient also improved and the damage to the counterface was serious. In order to further improve the tribological performance of the PTFE composite organic filler AF and PI was used. The results show that5wt.%PI filled10wt.%PEEK/PTFE composites exhibits best anti-wear behavior, the volume wear rate is only1.497×10-6mm3/Nm, it is improved630times compared with pure PTFE, it also shows excellent mechanical properties and low coefficient of friction, excellent wear resistance, smaller surface damage, which is an excellent dynamic sealing material for Stirling engine.Finally, a combination of theoretical and empirical methods for the life prediction of piston rings of Stirling was selected. In harsh conditions, the composite exist wear and creep. Wear equation and creep constitutive equation of oil-free polymer based composites were formed respectively. And calculate the predicted life values of both raw materials and new materials when the wear exists only. In the meanwhile, comparative analysis was done, the advantages of new material was shown intuitively. The model is used to predict life span and guide the design or the selection of piston rings conveniently.