Method and apparatus for adapting minimum torque converter slip for neutral idle control

A method of learning an amount of naturally occurring slip at a plurality of temperatures and controlling an amount of torque converter (TC) slip across a hydrodynamic torque converter assembly in a transmission in response to the naturally occurring slip, the method comprising:

• recording a TC slip value baseline data point at each of a plurality of different temperatures, wherein the baseline data points each share a common magnitude;
• measuring an actual TC slip value data point at a predetermined temperature;
• adapting the set of baseline data points using the actual TC slip value data point to thereby form a set of adapted TC slip value data points by:
• adapting a first number of the baseline data points downward to the level of the actual TC slip level data point, wherein the first number includes all of the baseline data points having a temperature greater than or equal to the predetermined temperature of the actual TC slip value data point;
• plotting a line between the actual TC slip value data point and each of a second number of the baseline data points, wherein the second number includes all of the baseline data points having a temperature less than the predetermined temperature;
• and
• adapting each of the second number of the baseline data points to a level of a predetermined one of the lines plotted between the actual TC slip value data point and each of the second number of the baseline data points;
• and
• controlling, via a controller, the amount of TC slip during a neutral idle (NI) state of the transmission using the set of adapted TC slip value data points as the naturally occurring slip to thereby minimize idle fuel consumption.

A vehicle comprising:

• an engine having an output shaft;
• a transmission having an input shaft;
• a hydrodynamic torque converter assembly operable for selectively coupling the output shaft to the input shaft, the hydrodynamic torque converter assembly including:
• a pump connected to the output shaft, a turbine connected to the input shaft, fluid, and a stator configured to redirect the fluid from the pump to the turbine;
• a sensor for measuring an amount of torque converter (TC) slip across the hydrodynamic torque converter assembly;
• and
• a controller operable for calibrating the amount of TC slip during a first transmission state, and for controlling the amount of TC slip during the first transmission state and a second transmission state that is different from the first transmission state;
• wherein the controller is configured to measure a plurality of actual TC slip data points, and to minimize idle fuel consumption by continuously adapting a TC slip profile to more closely approximate a natural slip curve of the vehicle in response to the plurality of actual slip TC slip value data points.