OIL DRAIN CONTROL DEVICE AND METHOD OF AUTOMATIC TRANSMISSION FOR IMPROVING SAFETY OF SHIFTING CONTROL AND SHIFTING EFFICIENCY BY PROPER CONTROL OF PRE-FILL TIME

摘要

PURPOSE: An oil drain control device and a method of an automatic transmission are provided to exclude shift flare in shifting 2 to 3 and 3 to 4 speed by regulating properly the drain amount of oil and to improve stability and shift quality by controlling pre-fill time according to a stop time and the temperature of the oil. CONSTITUTION: An oil drain control method of an automatic transmission is composed of steps for detecting all operation state-information of a vehicle if an engine starts after the vehicle stops for a constant time with turning off the engine(S101); deciding if the state information of the vehicle satisfies pre-fill time control conditions(S102); computing the drain amount of oil for a present condition and regulating the drain of the oil supplied to a clutch(S103,S104); deciding if a pre-fill time release condition is detected while regulating the drain amount of the oil(S105); controlling hydraulic pressure after completing a pre-fill time control mode for a release condition and deciding if the pre-fill time control is completed for not the release condition(S106); and performing hydraulic controls if the pre-fill time control is finished.