CONTROL DEVICE OF AUTOMATIC TRANSMISSION OF VEHICLE FOR IMPROVING DURABILITY BY REDUCING OVERSHOOT OF LINE PRESSURE IN RETURNING LINE PRESSURE FROM LOW PRESSURE IN STARTING AT VERY LOW TEMPERATURE

摘要

PURPOSE: A control device of an automatic transmission is provided to increase the endurance by reducing sudden fluctuation of load applied to the automatic transmission and damage of the pulley or the belt, and to prevent slip of the belt by assembling a forward clutch or a reverse brake before increasing line pressure. CONSTITUTION: A control device of an automatic transmission is composed of an engine rpm detecting unit measuring rpm of the engine, a cranking decision unit deciding engine cranking to be started if engine rpm is over the reference value, and a line pressure detecting unit measuring actual line pressure. Time required for finishing overshooting of line pressure in increasing engine rpm after starting cranking is predetermined to low line pressure control command setting time. The line pressure control unit outputs normal line pressure control command to the line pressure control system and maintains normal line pressure if actual line pressure is more than the predetermined pressure over the low line pressure control command setting time.