The air-hybrid engine absorbs the vehicle kinetic energy during braking, puts it into storage in the form of compressed air, and reuses it to assist in subsequent vehicle acceleration. In contrast to electric hybrid, the air hybrid does not require a second propulsion system. This approach provides a significant improvement in fuel economy without the electric hybrid complexity. The paper explores the fuel economy potential of an air hybrid engine by presenting the modelling results of a 2.5 lt. V6 SI (spark-ignition) engine equipped with an electrohydraulic camless valvetrain being used in a 1531 kg passenger car. It describes the engine modifications, thermodynamics of various operating modes, and vehicle driving cycle simulation. The intake-only switching between compressed air tank and the intake manifold is a low cost approach to the practical application of air hybrid operation for spark-ignition engines. The intake air switching with a double-barrel intake manifold remains usable. The exhaust manifold and the emissions aftertreatment system are not affected by the proposed engine modifications. The timing and duration of all engine valves is optimised and the engine maps for each mode are constructed with the intent to maximise air collection and minimise air use at all engine operating conditions. The air hybrid modelling resulted in fuel economy improvement of 64% and 12% in city and highway driving, respectively, compared to the conventional baseline vehicle. This is similar to improvements available from hybrid electric vehicles, but without reductions in vehicle weight to compensate for additional hardware, without reduction in engine displacement, and without the complexity associated with a second propulsion system.
Using camless valvetrain for air hybrid optimization
Der Einsatz variabler Ventilsteuerung bei der Optimierung eines Drucklufthybridantriebs
2003
13 Seiten, 28 Bilder, 1 Tabelle, 8 Quellen
Conference paper
English
Betriebsweise , Betriebszustand , Druckluft , elektrohydraulische Steuerung , Energierückgewinnung , Hybridantrieb , Kolbenkraftmaschine , Kraftstoffeinsparung , Modifikation , Optimierungssimulation , Otto-Motor , thermodynamischer Wirkungsgrad , Ventilsteuerung , Ventilverstellung , Verbesserung , variable Ventilsteuerung
Using Camless Valvetrain for Air Hybrid Optimization
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