Method and apparatus for operating a transmission coupled to an engine for enhanced fuel efficiency characteristics

A method for controlling a drive line assembly having (i) an engine driving an engine output shaft, (ii) an engine speed sensor which generates engine speed signals indicative of a speed of the engine output shaft (iii) a fuel injector operable to regulate fuel flow to the engine, (iv)

• a transmission driven by the engine output shaft and having a number of gear ratios, and (v) a controller, comprising the steps of:
• storing a predetermined maximum efficiency curve of engine speed versus torque output, the storing step including the step of deriving the predetermined maximum efficiency curve from specific fuel consumption data for the engine;
• determining the engine speed from the engine speed signals;
• determining a transmission speed;
• limiting fuel flow the fuel injector supplies to the engine to cause the engine to operate along the predetermined maximum efficiency curve for the engine speed;
• controlling shift points between the number of gear ratios based on the predetermined maximum efficiency curve;
• generating a shift command to cause the transmission to shift to a more fuel efficient operating point, and
• storing a primary upshift point and a secondary upshift point between each of the number of gear ratios with the controller based on the predetermined maximum efficiency curve, wherein the primary upshift point occurs at a higher transmission speed than the secondary upshift point.