Thermal Analysis Of Friction Pair Of Wet Multi-disc Clutch

As an important component widely used in vehicles, ships and engineering machineries, wet multi-disc clutch transmits power which comes from engine, depending on the friction force between friction discs and steel discs. In the engagement process of wet multi-disc clutch, the friction pairs are clamped by the piston pressed by control oil. Because of the rotation speed difference between driving parts and driven parts, relative sliding exists in the friction pairs, and a mass of friction heat is generated. After the thermal flux enters into friction discs and steel discs, the temperature fields in these discs are affected, and then the thermal stress fields are generated, changing the mechanical status in discs. Changes of temperature fields and thermal stress fields caused by friction heat is a key factor of the failure of clutch, resulting in the hot cracks, warping of discs, regional burning loss and stripping of surface materials. Therefore, this work has considerable theoretical significance and practical value, to solve the failure problem of clutch caused by friction heat.According to the basic structure of wet multi-disc clutch, the geometrical model of friction pair is simplified reasonably, as well as the friction heat and its distribution theory are introduced. Based on some accurate boundary conditions, the temperature fields and thermal stress fields of friction discs and steel discs are simulated using finite element model. The Temperature field of friction discs and steel discs are obtained, and its regularities of distribution are studied spatially and historically. Thermal stress field of friction discs and steel discs are also obtained, furthermore, its spatial and historical regularities are studied.Theoretical analysis of thermoelastic instability in the friction pair of clutch is also researched, while temperature fields, displacement fields and stress fields of symmetrical and antisymmetrical steel discs are deduced. The characteristic equations and critical velocities of thermoelastic instability are obtained. The influence rules, such as wavenumber of perturbation, disc thickness and symmetry of disc, which can affect thermoelastic instability of the friction pair, are studied particularly.Our research results will be improved the performance of wet multi-disc clutch and its life span, as well as the foundation is established for the design of high-performance wet multi-disc clutch.