Analysis On The Reciprocating Seal Mechanism Of The Aircraft Hydraulic Cylinder

The performance of the cylinder is decided by the seals of aircraft hydraulic cylinder, so the safety and efficiency of airplanes is influenced by them. The reciprocating seal mechanism of the aircraft hydraulic cylinder was analyzed by modeling and simulation. The characteristics of the O ring and the VL seal was studied. The influence of the multi-field coupling condition on the VL seal was discussed. The thesis mainly includes the chapters following:Chapter 1:Introduction. The review of aircraft hydraulic seal, the domestic and overseas research status were introduced. Besides, the objectives, significances and research contents were outlined.Chapter 2:The characteristics of the aircraft hydraulic cylinder seal were analyzed. The basic theories used to analyze the performance, life and reliability of the seal were discussed, which includes:seal material, sealing theory, facial wear failure and fatigue failure.Chapter 3:The performance of the O ring was analyzed by finite element method. The contact pressure distribution and the inner stress distribution were obtained with ANSYS. The influence of different compression ratios, tensile ratios and velocity directions on the O ring performance, such as leakage, reliability and life were discussed.Chapter 4:The superiority of the VL seal structure is analyzed. Firstly the VL seal model was built in ANSYS, the simulation of VL seal was carried out. The result shows that the VL seal structure adapts against high fluid pressure, and the principle of the special pressure distribution of the VL seal was pointed out. Secondly the contact pressure distribution of the VL seal is compared with the O ring and the step seal. At the last, the frictions and leakages of these three kinds of seals were computed respectively and the result shows VL seal has the best performance of leakage and liability among them.Chapter 5:The influences of multi-physical field coupling condition on the performance of VL seal was studied. Aimed to investigate into the influences of working conditions such as different pressures, temperatures and velocities on the performance of the VL seal of the aircraft cylinder. The mixed lubrication theory was employed to build the macro and micro multi-field coupling model of the VL seal. The characteristics of macro contact pressure, micro contact pressure and oil pressure distribution under different fluid pressures were analyzed. The useful influence rules were obtained from the studies.Chapter 6:The summary and prospect. Developments and achievements of this topic research are summarized. The problems encountered and prospect of it are presented.