Patent ID: 8682554

Claim:
A control device of a lock-up clutch for controlling an engagement state of the lock-up clutch, a torque converter mounted on a vehicle being provided with the lock-up clutch, the control device comprising: a facing temperature estimating section for calculating an estimated value of facing temperature of the lock-up clutch; a temperature comparing section for comparing the estimated value of the facing temperature calculated by the facing temperature estimating section with first threshold temperature defined in advance; a storage section for storing a plurality of target slip ratio maps, each of the target slip ratio maps including a characteristic line of a target slip ratio for the lock-up clutch; and a slip control section for controlling a slip ratio of the lock-up clutch on the basis of the target slip ratio retrieved from one of the plurality of target slip ratio maps, wherein the plurality of target slip ratio maps include a normal slip ratio map having a characteristic line of the target slip ratio defined in accordance with an engine load at a normal vehicle running condition and a modified slip ratio map having a characteristic line of the target slip ratio to become a facing calorific value lower than a facing calorific value corresponding to the slip ratio retrieved from the normal slip ratio map, and wherein, the slip control section carries out control to switch the target slip ratio map from the normal slip ratio map to the modified slip ratio map in the case where the estimated value of the facing temperature continues to exceed the first threshold temperature for more than a predetermined time when using the normal slip ratio map; and wherein the modified slip ratio map includes a first modified slip ratio map having a characteristic line of the target slip ratio larger than the target slip ratio on the normal slip ratio map and a second modified slip ratio map having a characteristic line of the target slip ratio smaller than the target slip ratio on the normal slip ratio map.