Torque Converter Lockup Clutch Slip Modeling in NVH Simulation

Recent automotive powertrain trends show engine downsizing, turbo, and cylinder deactivation increase the high vibration in engine output. In addition, increasing complexity in the transmission system is more sensitive to vibration. All of these recent trends demand very high vibration isolation requirements. One of the vibration isolation methods in the automatic transmission system is applying slip to the torque converter clutch. Understand clutch system characteristics and their behavior to perform efficient vibration isolation by clutch slip. Noise vibration and harshness (NVH) simulations are necessary to understand the vibration isolation performance when the slip is applied to the torque converter clutch. One of the main challenges in this type of NVH simulation has been the proper clutch modeling. Torque converter lockup clutch is sensitive to the facing material, automatic transmission fluid, geometry of the friction disc and mating components, and lockup clutch actuating system strategy. Changes to these factors mentioned but not limited to will create changes in clutch slip response. In this study, simulation modeling of a lockup clutch in the torque converter and the response parameter to capture the slip behavior shown. The simulations are also compared and correlated to the actual vehicle test.