Theoretical and experimental studies of air-hybrid engine operation with fully variable valve actuation

As an alternative to the electric hybrid powertrain, air-hybrid engine concepts have the potential to achieve regenerative braking and air-assisted engine operations for low-carbon vehicle applications. Over the last few years, systematic studies have been carried out by the authors on a number of air-hybrid engine concepts. This paper presents the modelling and experimental results of air-hybrid engine operation enabled by fully variable valve actuation (FVVA). The principle and key operating features of such an air-hybrid engine will be presented first. This is followed by a detailed theoretical analysis of the two-stroke compression and expansion operations enabled by the FVVA system. Finally, experimental results will be presented with regard to the actual performance of a single-cylinder engine operating in the compression mode and expansion mode through the Lotus active valve train system. copyright © 2012 by institution of mechanical engineers.