Influence of Valve Overlap Strategies on Residual Gas Fraction and Combustion in a Spark-Ignition Engine at Idle Chalmers University of Technology

Format:

Conference/Event

Author/Creator:

Sandquist, Håkan, author.

Conference Name:

International Fuels and Lubricants Meeting and Exposition (1997-10-13 : Tulsa, Oklahoma, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 1997

Summary:

This work investigates the influence of valve overlap strategies on residual gas fraction, combustion parameters and cycle to cycle IMEP variations on a Volvo four-valve pentroof single cylinder SI engine at idle. The mass fraction of residual gas was recorded as a function of valve timing. The measurements employed both symmetrically positioned overlaps with varied overlap duration and constant overlap duration where the overlap center position was displaced relative to TDC. The engine was running on true idle and the exhaust-intake pressure difference was approximately 0.7 bar. Results from one dimensional engine simulations have been compared with the experimental data.It is shown that there are factors affecting the burn duration as much as, or under certain circumstances even more than, the residual gas fraction. A displacement of the overlap center position 10 CAD ATDC results in increased burn duration and cyclic IMEP variations while the residual gas fraction decreases. The effective compression ratio is the most important factor. A discussion of other effects is also given

Notes:

Vendor supplied data

Publisher Number:

972936

Access Restriction:

Restricted for use by site license