Lock-up control system for lock-up type automatic transmission

Claim 1

A lock-up control system for a lock-up type automatic transmission of an automotive vehicle having an engine, the lock-up type automatic transmission including a torque converter with a lock-up clutch, the torque converter being shiftable into a lock-up state or a torque converter state, the lock-up control system comprising: means (201-206) for determining whether the automotive vehicle is operating in a predetermined lock-up range or not and for generating a lock-up permission signal (S L ) that indicates that the automotive vehicle is operating within said predetermined lock-up range; means (60,61) for detecting a various kinds of gear shifting commands occurring within the lock-up type automatic transmission; gear shifting detector means for generating a gear shift signal when said detecting means detects one of said various kinds of gear shifting commands, said gear shift signal having a duration which is variable depending upon a kind of gear shifting command detected by said detecting means; and means (252,253,254,31) for receiving said lock-up permission signal (S L ) and said gear shift signal for causing the lock-up torque converter to lock up when said lock-up signal is present while said gear shift signal is absent and for allowing the torque converter to operate in a torque converter state for a duration corresponding to a duration of the presence of the gear shift signal is present even if the lock-up permission signal is present.