System and method for preventing overheat of torque converter

In a torque converter automatic transmission of a motor vehicle powered by an engine,

• an overheat prevention system of the torque converter, comprising:
• first means for detecting the temperature of a hydraulic fluid in an oil pan of the transmission;
• second means for deriving an existing operation load of the engine;
• third means for deriving an overheat judging reference temperature that lowers as the operation load of the engine increases;
• and
• fourth means for carrying out an operation to suppress overheat of said torque converter when the temperature of the oil pan fluid temperature exceeds said overheat judging reference temperature.

In a torque converter automatic transmission of a motor vehicle powered by an engine,

• an overheat prevention system of the torque converter, comprising:
• a first unit which detects the temperature of a hydraulic fluid in an oil pan of the transmission;
• a second unit which detects whether the engine is under high load condition or low load condition;
• a third unit which derives an overheat judging reference temperature in accordance with the detection of said second unit, said overheat judging reference temperature indicating a first reference temperature upon detection of the high load condition of the engine by said second unit and indicating a second reference temperature upon detection of the low load condition of the engine by said second unit, said first reference temperature being lower than said second reference temperature;
• and
• a fourth unit which carries out at least one given operation to lower the temperature of the torque converter when the temperature of the hydraulic fluid in the oil pan exceeds said overheat judging reference temperature.

In a torque converter automatic transmission of a motor vehicle powered by an engine,

• a method of suppressing overheat of the torque converter, comprising:
• detecting the temperature of a hydraulic fluid in an oil pan of the transmission;
• detecting whether the engine is under high or low load condition;
• deriving an overheat judging reference temperature in accordance with the detection as to whether the engine is under high or low load condition, said overheat judging reference temperature indicating a first reference temperature upon detection of the high load condition and indicating a second reference temperature upon detection of the low load condition, said first reference temperature being lower than said second reference temperature;
• and
• carrying out a given operation to lower the temperature of the torque converter when the temperature of the hydraulic fluid in the oil pan exceeds said overheat judging reference temperature.