Method of predicting transmission oil temperature

A method for estimating, in real time, the temperature of automatic transmission fluid of an automatic transmission having a torque converter, said method comprising the steps of:

• selecting a thermal inertia constant related to transmission fluid volume and to materials used to construct said automatic transmission;
• generating a thermal inertia signal from said thermal inertia constant;
• generating an initial fluid temperature signal related to an estimated initial temperature of said transmission fluid;
• generating a plurality of heat flow signals representing heat gain and heat loss from said automatic transmission;
• estimating said fluid temperature based on said plurality of heat flow signals, said thermal inertia signal, and at least one of said initial fluid temperature signal and a previous estimated fluid temperature signal, and generating an estimated fluid temperature signal;
• generating a normal operating temperature range signal related to a normal operating temperature range of said fluid in said automatic transmission;
• comparing said estimated fluid temperature signal to said normal operating temperature range signal, generating a hot temperature signal if said estimated temperature signal exceeds said normal operating temperature range signal and generating a cold temperature signal if said estimated temperature signal is below said normal operating temperature range signal;
• providing at least one of accelerated automatic transmission lock-up and modification to a shift schedule of said automatic transmission in response to said hot temperature signal to compensate for increased fluid temperature;
• and
• providing at least one of postponed automatic transmission lock-up and modification to said shift schedule of said automatic transmission in response to said cold temperature signal to compensate for said decreased fluid temperature.