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A powertrain simulation model to translate the demands of a vehicle driving schedule into an engine RPM/torque versus time trajectory is developed. The formulation of a time density matrix in the speed/load plane of the engine allows a rational approach to the selection of dynamometer test points for emission control strategy development, fuel economy improvement and/or component development and evaluation. Steady-state engine dynamometer data combined with the results of the powertrain model can be used to project emissions and fuel economy values for an entire drive cycle such as CVS-Hot. This provides the development engineer with a powerful tool to make preliminary assessments of the potential of various control strategies or intended component modifications without the necessity of building a complete vehicle prototype. It also provides the basic building block for optimizing emission control strategy to meet required constraints with maximum fuel economy.

Issues surrounding the applicability of combustion modeling and diagnostics (CMD) to engine combustion system development, and to the advancement of engine technology as a whole, are systematically reviewed. The unique technical aspects of the environment in which CMD must function are identified, thereby providing a basis for assessing the applicability of CMD to the very particular needs of combustion system research, development and engineering activities. The major obstacles which inhibit the effective use of CMD techniques are discussed and a set of general, technical and organizational recommendations is developed which points towards ways of realizing the full current and future potential of this methodology.

A comprehensive simulation has been developed which describes the dynamic response of a turbocharged, six cylinder diesel engine fueled by an in-line pump-line-nozzle system with electronic control of a solenoid-actuated rack. The mathematical models of components, governing strategies and control algorithms are general, having been developed to address issues related to the dynamic response and control of both components and the overall system in a variety of engine propulsion and power system applications. The physical principles and salient characteristics of the independent subsystem models are reviewed. Results of the overall system simulation, featuring interactions between the engine, microprocessor-based governor, and solenoid-actuated rack are presented to demonstrate the utility of dynamic simulation as a basis for evaluating system performance and exploring control strategies for optimum response.

A comprehensive simulation has been developed which describes the dynamic behavior of truck powertrains employing. Detroit Diesel Allison heavy duty diesel engines equipped with the Detroit Diesel Electronic Control System (DDEC). The simulation, was developed to address those issues related to DDEC fuel control that impact upon engine smoke production and upon vehicle driveability and responsiveness, and to identify components in the powertrain which interact with the control system. The simulation contains four major submodels: (1) torque and transient air system model of the 8V-92 turbocharged/inter-cooled two-stroke engine; (2) discrete event, DDEC controller/governor model; (3) tandem rear axle drive, torsionally compliant, manual transmission driveline model; and (4) flexible driver simulator and external event module.

The development of I.C. engines is a sophisticated process bringing together a multitude of specialists. It is important that all of these specialists work together as a team and communicate effectively. One tool of communication can be an integrated engineering software package that simulates many of the important facets of engine operation, and describes their essential interactions. Then, if changes are made in one part of the hardware or in operating conditions, their effects on other components of the system can be assessed. This paper describes initial efforts made in that direction through the development of a comprehensive engine simulation code, IRIS, which permits a coupled analysis of engine performance and component thermal and structural state.