Research On Oil Seal Lip Temperature And Its Effect On Working Performance

With the modern industrial technology development, construction machinery willtend to be of high speed, heavy burden and high power, this more and more requires thehigh capability of oil seal. But most seal failure of oil seal is caused by the hightemperature caused by friction heat of seal lip. It would cause friction between seal lipand shaft, consumption of the mechanical energy is changed into heat energy, Theaccumulation of heat energy in the contact zone produces large amount of friction heat,and leads to the increase of lip temperature, accelerates aging, harden and wear of lipposition, effects of the use of performance and working life of oil seal. The process offriction and heat dissipation of oil seal relates to the heat conduction and convection, butthe process of convection heat transfer of engine oil and shaft on lip temperature isinvolved little.Considering lip deformation and the lubricating oil thermo-viscosity effect, thispaper has derived the expression of oil film thickness related to temperature and theexpression of lip contact width and circumferential load, established thetwo-dimensional axisymmetric numerical model of oil seal. The influence of oil sideangle, shaft diameter, shaft speed and circumferential load on the oil seal lip temperaturedistribution, maximum temperature and the influence of lip temperature on workingperformance are got by theoretical analysis and numerical simulation. The results showthat the temperature gradient is large near seal lip, the frictional heat generated betweenoil seal and shaft is dissipated mainly by shaft and engine oil. The oil side temperature onthe lip surface of friction is higher than the air side temperature, while the maximumtemperature on the lip surface of friction close to oil side. With the increase to60°from45°of oil side angle, friction heat production per unit area increases with little effectgradually, while lip maximum temperature is almost constant. The maximum temperatureof seal lip increases linearly with the increase of shaft speed and circumferential load.With the increase of shaft diameter, lip maximum temperature and lip maximumtemperature gradient increases. Speed has minimal impact on friction coefficient, oil filmthickness and friction torque between seal lip and shaft. With the increase ofcircumferential load, friction coefficient decreases and friction torque increases. With theincrease of shaft diameter, friction torque and friction torque gradient increases. Lipmaximum temperature increases with the increase of circumferential load, viscosity of engine oil and oil film thickness decreases. When judged lubrication failure by the criticalfilm thickness, the selection range of circumferential load and other parameters of oil sealdesign required is obtained.