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This paper describes a dynamic simulation model of a turbocharged diesel powertrain equipped with the Navistar T444E V8 engine. The T444E engine is the first diesel to utilize dynamic injection pressure control. Emphasis of this paper will be on powertrain dynamics pertinent to electronic control system design and development. Applications of the integrated system model include control strategy design and development of idle speed regulation, cruise and power take off control, driveline surge compensation, engine starting, injection timing and pressure control, and exhaust pressure control. The reported powertrain model features a hybrid multi-rate sampled data model for the diesel engine. Actual fuel injection is event-based with reference to crank-angle. Control algorithms are executed at fixed rates independent of injection events. Analyses of idle stability, engine-driveline dynamic characteristics, and multi-loop interaction are presented.

A diesel engine coupled to a CVT (Continuously-Variable Transmission) was computer controlled to maintain constant CVT output speed. The engine operated on power demand on a torque-speed schedule giving low BSFC. The engine-CVT-computer combination is viewed as an augmented engine, to which a conventional power train can be added to produce required vehicle speeds. On farm tractors, the pto (Power Take Off) shaft and other functions requiring constant speed would be driven by the CVT output shaft. Fuel savings with the augmented engine depend on engine load; at half load or less, a prototype augmented engine produced fuel savings of 15% or more.