Modeling the effect of variable cam phasing on volumetric efficiency, scavenging and torque generation in SI engines
(English)In: Control Engineering Practice, ISSN 0967-0661Article in journal (Other academic) Submitted
In a mean value engine model, the mass flow of air through thecylinders is determined by the air density, the engine speed, and thevolumetric efficiency. For modern engines the volumetric efficiency model mustalso account for the effect of variable valve timings. In this work the effect of the valve overlap is considered. Thevalve overlap is the number of crank angle degrees that both valvesare open simultaneously. When the valve overlap is significant,there may be fresh air that flows directly through the exhaustvalve, known as scavenging, which affects the torque. Steady-state torque measurements are used to estimate the amount of scavenging. The volumetric efficiency and scavenging models derived in the paper are shown toimprove the predictions of the engine torque significantly, alsounder transient conditions.
IdentifiersURN: urn:nbn:se:kth:diva-102842OAI: oai:DiVA.org:kth-102842DiVA: diva2:557054
QS 20122012-09-262012-09-262012-09-28Bibliographically approved