A sophicated helical port with a swirl control valve (SCV) for a 4 valve engine has been newly developed. This port satisfies two conflicting requirements, that is, improving the combustion at part load and maintaining high volumetric efficiency at full load. Analysis of pressure, flowfield and mixture formation in a cylinder have been carried out to investigate the mechanism to improve combustion by comparing it with two other ports; a straight port and a helical port where an ordinary helical port is used for one port of two intake parts. The analysis of the cylinder pressure diagram showed that the burning duration of the helical port with SCV is shorter than that of the straight port and is also shorter than the helical port with the same swirl ratio as that of the helical port with SCV. Analysis of the flow in the cylinder by LDV and visualization by a laser sheet technique explained the difference in combustion duration. In the case of the helical port with SCV, the swirl center moved more actively during the compression stroke than in the case of the ordinary helical port and was apart from the cylinder center, which suggested a higher turbulence around a spark plug which makes the combustion faster in the 4 valve engine. (Copyright (c) 1988, Toyota Motor Corporation.)
Effect of Swirl on the Combustion Characteristics of 4 Valve Engines
1988
7 pages
Report
No indication
English
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