Development of a Variable Valve Timed Engine to Eliminate the Pumping Losses Associated with Throttled Operation 860537

The primary objective of this research program was to reduce pumping losses associated with the standard air intake system for spark ignition engines. This was accomplished by controlling the induction of the air/fuel charge with variable valve timing applied to the intake valves.
The intake manifold pressure was maintained at atmospheric pressure and the timing of the intake valves was electronically adjusted to allow the induction of an air/fuel mixture sufficient to support the required engine load. This variable valve timing allowed flexibility in scheduling the intake valve timing events, simulating throttled operation with improved efficiency. Brake-specific-fuel-consumption (BSFC) was improved significantly, while air/fuel ratios remained stabilized, with no sacrifice in load control.


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