| The clutch is a common component in mechanical transmission system with two specific modes,separation and transmission.Sleeve and shell assembly,steel sheet and friction disk assembly are key parts of clutch.In a wet clutch,whether the oil pressure inside the sleeve can reach the required will influence the normal transmission of torque,leakage failure is the direct factor causing the oil pressure below normal value.To solve the leakage failure caused by different factors of products,study of sleeve leakage failure based on lifecycle of design,manufacture and usage is carried out in this paper.A mathematical model for leakage failure of various influencing factors is established based on actual working conditions.(1)Based on actual working conditions of the clutch sleeve and the shell assembly,the mode of fitting between clutch sleeve and shell is ascertained.The corresponding finite element model is established to analyze and determine the causes of leakage.After the factors are further discussed,a mathematical model of gap change is established and used to discuss the influence of various factors on the gap size.(2)Based on the mathematical model of leakage failure,the improvement scheme of clutch sleeve is proposed.Finite element model and mathematical model of the scheme are established and numerical calculation is carried out.The effectiveness of the scheme is confirmed when the numerical calculation results are compared with that of the unimproved respectively.Instance test is also carried out and its result also prove the effectiveness.For further discuss the accuracy of the mathematical model,the mathematical model results of the unimproved and improved assembly are compared with the finite results respectively.(3)Leakage failure of clutch sleeve during service period is studied.Main reasons that include abrasion of the friction pair consisted of sleeve and shell for increasing of gap size are analyzed and ascertained.Micro convex body model of the improvement is established.Abrasion mathematical model and service life model of sleeve step are established based on the micro convex body dynamic contact model and abrasion theory.Service life of the clutch sleeve under normal working conditions is predicted with the service life model,and it turned that the calculation result fit actual life.Finally,the result of life prediction is analyzed to ascertain the main factors affecting the speed of abrasion and the degree of influence on the service life is discussed.(4)Contact model of friction surface is established based on surface contact theory and friction characteristics of friction disk and steel sheet assembly.Considering the abrasion state of friction disks,the abrasion model of the friction disk is established with the contact model of friction surface,and its reliability is discussed with the comparison between calculation results of abrasion model and sliding grinding theory.The service life of the friction disk is predicted with the abrasion model,and actual working factors affecting the service life are discussed.Results of this research provide theoretical basis for studying the leakage failure of key components of clutch.It has certain technical reference and engineering application value for researching similar leakage failure and improving sealing performance of the key components for the automotive gearbox clutch. |
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