A Study of Air to Fuel Transient Response and Compensation with Different Fuels

Format:

Conference/Event

Author/Creator:

Almkvist, Göran, author.

Conference Name:

International Fuels and Lubricants Meeting and Exposition (1994-10-17 : Baltimore, Maryland, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 1994

Summary:

In order to fulfill the future LEV exhaust emission standards, with different fuel specifications it is necessary to achieve a good control of the air to fuel ratio under transient conditions especially during the warm-up period. The objective in this report was to clarify the controlling factors of the exhaust auto fuel ratio response dependency of different fuels in order to provide a correct compensation strategy.A mathematical model based on a manifold air flow model and a fuel film model, together with a time delay between air and fuel supply to the engine during the transient, was used for data matching of the measurements. The fuel film model includes a deposit factor (X), an evaporation time constant (τ) and a time delay (Δt).Tests were carried out with three different fuels, typical European unleaded fuel. US California phase 2 fuel and US low volatility fuel.The results from the models of delay and wall wetting effects were used for compensation strategy development.Since wall wetting varies with e.g. fuel properties and engine ageing, observer models are discussed to adapt X and τ from the λ error feedback. This adaptation is made complicated due to the load and engine speed dependency of the wall film mass.The results show that:

Notes:

Vendor supplied data

Publisher Number:

941931

Access Restriction:

Restricted for use by site license