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Piston and Ring Variables Affect Exhaust Hydrocarbon Emissions
ISSN: 0148-7191, e-ISSN: 2688-3627
Published February 01, 1968 by SAE International in United States
Annotation ability available
Wide variations in exhaust hydrocarbon concentration have been traced to the angular position of the top compression ring gap. Furthermore, with a fixed gap position, equally large changes in exhaust hydrocarbon concentration have been correlated with blowby flow rate, which was chiefly determined by the smallest of the two compression ring gap areas. Enlarging gap area increases blowby volume, which lowers exhaust hydrocarbon output. It is believed that the air-fuel mixture in the piston-bore-ring crevices escapes combustion and that both gap location and blowby flow influence the amount of this hydrocarbon-laden gas which makes its way into the exhaust gas.
A modification of the piston and top ring, called the sealed ring-orifice design, has demonstrated the technical feasibility of reducing exhaust hydrocarbon concentrations by minimizing the crevice effect, while cutting blowby flow below that possible with production rings.
CitationWentworth, J., "Piston and Ring Variables Affect Exhaust Hydrocarbon Emissions," SAE Technical Paper 680109, 1968, https://doi.org/10.4271/680109.
- Daniel W. A. Wentworth J. T. “Exhaust Gas Hydrocarbons - Genesis and Exodus,” SAE Technical Progress Series 6 1964
- de K. Dykes P. “Piston Ring Movement During Blowby in High Speed Petrol Engines,” MIRA Report 1947/R/12 December 1947
- de K. Dykes P. “Pressure-Backed Piston Rings,” MIRA Report 1951/13 December 1951
- Bennett P. A. Murphy C. K. Jackson M. W. Randall R. A. “Reduction of Air Pollution by Control of Emission from Automotive Crankcases,” SAE Transactions 68 1960
- Wentworth J. T. General Motors Corp. “Internal Combustion Engine Having Piston With Sealed Compression Ring,” U. S. Patent No. 3,335,643 Aug. 15
- Cornelius W. Caplan J. D. “Improved System for Control and Measurement of Air Consumption of Single-Cylinder Engines,” SAE Quarterly Transactions 6 October 1952
- D'Alleva B. A. “Procedure and Charts for Estimating Exhaust Gas Quantities and Composition,” General Motors Research Laboratories Report, SP-21 May 15 1960