Abstract: The net engagement pressure of a torque converter clutch is controlled in response to a commanded slip and a slip error indication, for isolating engine torque perturbations from the vehicle driveline. The transmission of an excessive level of engine speed perturbation is detected and used to develop a correction amount for the measured slip. The correction amount increases the slip error indication and causes the slip to be controlled at a higher level, thereby reducing the amount of transmitted engine torque perturbation.

Abstract: The net engagement pressure of a torque converter clutch having a negative slope capacity vs. slip characteristic is controlled to stably regulate the clutch slip, and thereby isolate engine torque perturbations from the vehicle driveline. The pressure is scheduled with a proportional term responsive to transient slip speed deviations and an integral term responsive to steady state slip speed deviations. Feed forward terms responsive to the throttle changes which force steady state slip speed deviations act to increase the speed of response of the integral term.