ABSTRACT The torque converter and torque converter clutch are critical devices governing overall power transfer efficiency in automatic transmission powertrains. With calibrations becoming more aggressive to meet increasing fuel economy standards, the torque converter clutch is being applied over a wider range of driving conditions. At low engine speed and high engine torque, noise and vibration concerns originating from the driveline, powertrain or vehicle structure can supersede aggressive torque converter clutch scheduling. Understanding the torsional characteristics of the torque converter clutch and its interaction with the drivetrain can lead to a more robust design, operation in regions otherwise restricted by noise and vibration, and potential fuel economy improvement. The objective of this paper is to present a generalized integration summary for torque converter clutches (TCC) to enable aggressive apply at high engine torques and engine speeds below 1500 rpm without adversely affecting noise and vibration (N&V) performance. The focus is on optimizing existing damper technologies found in a large percentage of current production automatic transmissions. The overall goal is to demonstrate that through proper hardware selection and TCC calibration, a balance between N&V and fuel economy can be achieved. A validated lumped parameter modeling technique for optimizing torque converter clutch hardware that comprehends the complete powertrain and driveline system is used to investigate required TCC hardware. A torsional isolation metric across the powertrain is presented for comparing the performance of various damper designs. For operating points with inadequate isolation a controlled amount of slip across the torque converter clutch is required to increase isolation. An analytical methodology for minimizing the amount of slip required to satisfy noise and vibration targets and maximize fuel economy is reported. Theeffect of gear state, torque converter slip and power delivered to the driveline on fuel economy are also discussed based upon powertrain dynamometer measurements. INTRODUCTION FUEL ECONOMY AND N&V CONSIDERATIONS Maximum fuel economy is determined by the thermodynamic limits of the internal combustion engine, while parasitic losses associated with the vehicle and the individual components of the transmission and driveline act to further reduce fuel economy. Drivetrain related losses can be diminished by optimizing hydraulic pumps, planetary gears sets, clutch packs, or overall transmission design by increasing ratio spread and the number of fixed gear states. The torque converter represents a significant source for improving fuel economy since it operates with efficiencies ranging from zero to just below 100 percent. When a lockup clutch or torque converter clutch (TCC) is included, efficiency is increased to 100 percent with full lockup or a slight loss in efficiency with a controlled amount of slip across the TCC commonly referred to as electronically controlled clutch capacity (ECCC) [ 1]. The recent design trend is to displace more of the hydrodynamic circuit of the torque converter with TCC damper hardware in proportion to the amount of time scheduled per function. Aggressive scheduling of the TCC, locked or controlled slip, can improve fuel economy, but can adversely affect drive quality and perceived noise and vibration (N&V), [ 2, 3, 4, 5]. From a drive quality perspective, degradation in throttle response can be noted because of reduced engine speed and turbine torque availability. N&V becomes a primary concern as attenuation of engine torsional vibration are significantly reduced as the torque converter transitions from Torque Converter Clutch Optimization: Improving Fuel Economy and Reducing Noise and Vibration2011-01-0146 Published 04/12/2011 Darrell Robinette, Michael Grimmer, Jeremy Horgan, Jevon Kennell and Richard Vykydal General Motors Company Copyright © 2011 SAE International doi:10.4271/