Device for controlling lock-up capacity of torque converter

A lock-up capacity control device of a torque converter, which drivingly couples a prime mover and a transmission and on which a lock-up mechanism is installed for engaging an input element on a side of the prime mover with an output element on a side of the transmission depending on a lock-up capacity, the lock-up capacity control device being configured to control the lock-up capacity depending on an operating condition, the lock-up capacity control device comprising:

• a lock-up capacity control means for controlling the lock-up capacity to a predetermined target capacity when a transition from a drive running state to a coast running state occurs;
• a timing means for measuring a time during which a slippage, which is a difference between a revolution speed of the input element and a revolution speed of the output element, is within a predetermined range when the lock-up capacity is controlled to the target capacity;
• and
• a capacity learning means for making a learning-correction to the target capacity such that the time measured by the timing means is brought to a predetermined target time.