Combustion Analysis on a Variable Valve Actuation Spark Ignition Engine Operating With E22 and E100 2017-01-1069

Variable Valve Actuation system (VVA) is a technology developed for improving fuel economy, reducing emissions, and enhancing engine performance mainly by reducing pumping losses. Many automakers have used VVA in their engine projects with excellent results. Usually, VVA systems are built to control the valve events in four different ways: changing the amplitude of the valve lift, the valve opening angle, the valve closing angle or a combination of those modes. A special attention at the calibration activity is needed to reach the optimum performance of this system, beyond this, it was necessary to develop a different way to calibrate, much more focused on the development of the combustion and the gas exchange process requiring an intense use of a pressure indicating system.

This work presents a comparison between different way of actuation in combustion analysis of a VVA system on a spark ignition engine. In this work a naturally aspirated spark ignition engine equipped with a variable valve actuation (FIAT MultiAir II) was used operating with gasoline (E22) and Ethanol (E100) in part-load condition. The cylinder filling was controlled by variation of the closing angle of the intake valve. Cylinder pressure, volumetric efficiency, temperatures and ignition angle were recorded by a pressure indicating system in the same break mean effective pressure conditions for each valve mode operation. The data was processed using Matlab scripts used to calculate the apparent heat release curves, energy conversion efficiency and generalized losses (pumping, friction and thermal).