Research on meshing stiffness and damping of spur gear considering elastohydrodynamic lubrication

ObjectiveAiming at the problems that existing calculations of gear mesh stiffness and damping ignore the influence of elastohydrodynamic lubrication (EHL) or require solving complex EHL system equations, this study was conducted to establish a more practical dynamic model of gear transmission systems and explore the influence law of EHL on the mesh stiffness and damping of spur gears.MethodsFirstly, based on the stiffness fitting formulas for line contact elastohydrodynamic friction pairs, a modified Ishikawa formula was proposed, in which the Hertz contact deformation in the original Ishikawa formula was replaced by the contact deformation of elastohydrodynamic friction pairs. Secondly, combined with the damping formula for line contact elastohydrodynamic friction pairs, the influences of gear structural parameters and operating parameters were systematically studied. Finally, the effectiveness of the proposed method was verified through comparative analysis.ResultsAfter considering EHL, the mesh stiffness of spur gears was significantly lower than that calculated by the original Ishikawa formula, and both mesh stiffness and damping showed periodic changes along the meshing line; both increased with the increase of input torque and transmission ratio, and decreased with the increase of modulus and lubricating oil viscosity. The influence of EHL was more prominent under high-speed, light-load, big-modulus and high-viscosity working conditions.