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

Claim 1

A lock-up control system for a lock-up torque converter for a lock-up type automatic transmission for an automotive vehicle having an engine, the automatic transmission having at least two gear positions and having a lock-up control valve which is operable to cause the lock-up torque converter to lock up, said lock-up control system comprising: means for generating a gear position signal indicative of one of the gear positions selected by the automatic transmission; means for storing predetermined lock-up vehicle speed values versus at least the gear positions and for generating a signal indicative of a lock-up vehicle speed value versus the one gear position indicated by said gear position signal; sensor means for generating sensor pulses having a frequency indicative of information related to the vehicle speed of the automotive vehicle; clock means for generating clock pulses having a predetermined interval; means responsive to one of said sensor pulses and said clock pulses for counting the other within a time interval between two adjacent pulses of said one pulses and for generating a vehicle speed signal indicative of the vehicle speed; means for receiving said signal indicative of the lock-up vehicle speed value and said vehicle speed signal and for generating a lock-up signal when said vehicle speed signal has a predetermined relationship with said signal indicative of the said lock-up vehicle speed value; and drive means for operating the lock-up control valve responsive to said lock-up command signal to cause the torque converter to lock up.