Thermal lubrication characteristics of hypoid Gear with non-Newtonian fluids considering roughness

Abstract

Based on Hertz contact theory and EHL, the model of elliptic contact elastohydrodynamic lubrication considering load, speed, roughness, thermal effect, and shear-thinning effect of non-Newtonian fluids is established. The variation trend of oil film pressure, thickness, and temperature with load, entrainment velocity, and the slide-roll ratio is analyzed. Then, several lubrication states considering roughness, the thermal effect, and the characteristics of non-Newtonian fluid are compared. Compared with the smooth surface, the roughness when RMS is 0.15 μm increases the maximum film pressure (P max) by 8.34%, increases the maximum film temperature (T max) by 7.18%, and reduces the minimum film thickness (H min)by 9.13%. The pressure and temperature are more sensitive to light load. The results are approximate to that of the smooth surface when the entrainment velocity is big enough. The pressure and thickness decrease with the increasing slide-roll ratio. The decreasing speed of the oil film thickness becomes faster as a result of the thermal effect. The roughness and the characteristics of non-Newtonian fluid have a significant impact on temperature.