METHOD FOR CONTROLLING A VEHICLE POWERTRAIN HAVING STEP RATIO GEARING AND A CONTINUOUSLY VARIABLE TRANSMISSION TO ACHIEVE OPTIMUM ENGINE FUEL ECONOMY

摘要

A method is disclosed for controlling overall transmission ratios (Fig. 3) in a vehicle powertrain with an engine (10), fixed multiple-ratio gearing (24) and infinetely variable ratio components (49). For a given vehicle speed and for a given vehicle traction wheel horsepower, the fixed multiple-ratio gearing and the infinetely variable ratio components are controlled to operate with an overall ratio that will permit the engine to operate with optimum efficiency.