Abstract: In internal combustion engines valve events and timings are among the most important parameters which have a major influence on the engines operation and volumetric efficiency.
By using cam less valve train strategy, improvement in fuel economy as well as an increase in entering air charge is found throughout the engine map with the largest benefits arising from low speed operation conditions. The system offers a continuously variable and independent control of virtually all parameters of valve motion. This permits optimization of valve events for each operating condition without any compromise.
In this paper we describe a phenomenological model for an unthrouttled operation of a cam less intake process of spark ignited (SI) engine. Initially the cylinder breathing dynamics is modeled and results are validated with experimental data of a conventional engine with cam- driven valve profile during unthruttled operation. Then we determine the most optimized intake valve profile in order to have the most volumetric efficiency and proper operation for each operating condition based on the existing model and using numerical techniques.

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Ref.: ASME, ICES-2006-1411, 2006.