The improvement of internal combustion engine is largely accomplished though the introduction of innovative actuators that allow optimization and control of the flow, mixing, and combustion processes. The realization of such a novel system depends on the existence of an operational controller that will stabilize the engine and allow experimental testing which, consequently, leads to further development of the actuator and the engine controller. This iterative process requires a starting point which is the development of a control-oriented model. Although not fully validated, the control-oriented model reveals issues associated with uncertainties, nonlinearities, and limitation of different subsystems. Moreover, it aides in defining the controller structure and the necessary parameters for the calibration of the closed loop system. In this paper (Part I) we describe the development process of a control-oriented model for a camless intake process. We first model the multicylinder crankangle-based breathing dynamics and validate it against experimental data of a conventional engine with cam-driven valve profile during unthrottled operation. We then employ the assumption of uniform air pulses during the intake duration and derive a simple input-output representation of the cylinder air charge, pumping losses and associated uncertainties that can be used for designing an electronic valvetrain controller (Part II). [S0022-0434(00)02901-4]

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