Influences of Deformed Film Gaps on Dynamic Torque Behavior of Hydroviscous Drive

Abstract

To investigate the effects of the oil film between deformed discs on the dynamic torque behavior of hydroviscous drive (HVD), a mathematical model incorporating film lubrication, asperity contact, and translational and rotational motion from a friction system is developed based on four kinds of representative film gap cases. The main analytical solutions including squeeze velocity, angular velocity of the driven disc, hydrodynamic torque, and total torque are obtained. Soft-start experimental tests are conducted to verify the feasibility of the theoretical model. The results show that both peak value of total torque and hydrodynamic torque increase with an increase in the divergent angle or the convergent angle. Due to the increase in squeeze velocity, surface asperity contact begins to dominate the dynamic torque behavior in the mixed and boundary lubrication regimes, which inevitably caused the soft-start process to become nonstationary. For all of the film gap effects, consideration should be given to both the dynamic torque response and improvement of the soft-start characteristics. Moreover, some key parameters including convergent angle, divergent angle, and location of the minimum or maximum initial film thickness have a great influence on the dynamic torque behavior. Based on the comparison with experimental results, the performance of the theoretical model is satisfactory.