Control system for automatic transmission, including coordinated frictional engagement element release control

A control system of an automatic transmission in which a frictional engagement element to be released according to a shift from a running range to a non-running range is connected with a plurality of pressure discharging lines of different fluid resistances, comprising:

• shift detecting means for detecting the shift from the running range to the non-running range;
• oil temperature detecting means for detecting the temperature of a fluid to actuate said frictional engagement element;
• and
• pressure discharging line selecting means for selecting the line to discharge the pressure therethrough from said frictional engagement element, on the basis of the temperature which is detected by said oil temperature detecting means,
• wherein said pressure discharging lines include a line for causing said frictional engagement element to communicate with a drain portion through a first shift valve;
• a line for causing said frictional engagement element to communicate with the drain portion via an oil passage having a second shift valve and an orifice;
• and a line for causing said frictional engagement element to communicate with a drain portion through said second shift valve, and
• wherein said pressure discharging line selecting means includes a first shift solenoid valve for outputting a signal pressure to switch said first shift valve;
• and a second shift solenoid valve for outputting a signal pressure to switch said second shift valve.

A control system for an automatic transmission in which a frictional engagement element to be released according to a shift from a running range to a non-running range is connected with a plurality of pressure discharging lines of different fluid resistances, comprising:

• shift detecting means for detecting the shift from the running range to the non-running range;
• oil temperature detecting means for detecting the temperature of a fluid to actuate said frictional engagement element;
• pressure discharging line selecting means for selecting the line to discharge the pressure therethrough from said frictional engagement element, on the basis of the temperature which is detected by said oil temperature detecting means;
• and
• another frictional engagement element to be released at a switching time from the running range to the non-running range,
• wherein said pressure discharging line selecting means includes means for discharging the pressure from said frictional engagement element through any of said pressure discharging lines at a predetermined time lapse after said another frictional engagement element begins to be released according to the switching to the non-running range.