Thermal mixed elastohydrodynamic lubrication analysis of involute helical gears with surface roughness

To address the issue of existing gear elastohydrodynamic lubrication studies neglecting surface roughness, a thermal-mixed elastohydrodynamic lubrication model for involute helical gears was established, incorporating principles from load-sharing and elastohydrodynamic lubrication theories. The finite difference method was used to obtain the numerical solution of thermo-mixed elasto-fluid lubrication of gear transmission, and the effects of different working conditions on the lubrication characteristics of helical gears were analyzed. Research shows that: engaging end oil film pressure and friction coefficient are significantly higher than engaging end, while the oil film thickness shows the opposite trend; an increase in speed will thicken the oil film and reduce friction, but it will exacerbate the temperature rise. Increasing the torque can increase the oil film pressure and temperature, but it will reduce the friction coefficient and film thickness. Enhanced lubricant viscosity substantially increases oil film thickness; the increase in surface roughness will lead to a significant increase in the coefficient of friction and temperature rise.