Lockup control system of automatic transmission

摘要

In a lockup control system of an automatic transmission with a lockup torque converter, a controller pre-stores a predetermined lockup control map including at least a predetermined coast slip lockup area, within which the system executes a slip lockup control mode under the vehicle's coasting condition, so that a speed difference between input and output speeds of the torque converter is brought closer to a predetermined value. The controller determines whether a first transition from the vehicle's driving condition to the predetermined coast slip lockup area occurs in a release mode of the lockup clutch or a second transition from the vehicle' s coasting condition to the predetermined coast slip lockup area occurs in the release mode. When the first transition occurs, the lockup clutch is conditioned in the slip lockup control mode. When the second transition occurs, the lockup clutch is conditioned in the release mode.