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1995 SAE International Fall Fuels and Lubricants Meeting and Exhibition
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Signal Reconstruction Applied to a Fast Response Flame Ionisation Detector

Cambridge Univ.-T. Summers, N. Collings
Published 1995-10-01 by SAE International in United States
The Fast-response Flame Ionisation Detector is used to measure levels of un-burnt hydrocarbons in the cylinder and exhaust of engines. Its fast response allows uHC emission processes to be resolved within an engine cycle.This paper describes a method for obtaining even greater detail by post-processing the output of the device using a Finite-Impulse Response (FIR) digital filter. The specification of the filter can be obtained by understanding the flow regimes within the sampling system. Examples from in-cylinder and exhaust sampling are presented with suggestions for implementation and further improvement.
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The Influence of the Fuel Hydrocarbon Composition on NO Conversion in 3-Way Catalysts: The NOx/Aromatics Effect

Shell Research B.V.-P. J. van den Brink
Shell Research Ltd.-C. R. McDonald
Published 1995-10-01 by SAE International in United States
Vehicle-based studies have shown that a reduction in the aromatic content of gasoline fuels can result in increased NOx emissions from catalyst-equipped vehicles. A study with simulated exhaust gas has shown that light paraffins, especially methane, are unreactive and cause substantial breakthrough of unreacted NO over the catalyst. However, unsaturated exhaust components including aromatics are effective reactants and play a large part in converting NO over the catalyst.Engine tests have shown that methane is predominantly produced by fuel paraffins and olefins, but hardly at all by aromatics. Thus it appears that methane generated during combustion of low aromatics fuels may be the cause, wholly or in part, of the poor NO conversion efficiency observed when catalyst-equipped cars are operated on such fuels.However, it cannot be excluded that low aromatics fuels are associated with increased air-to-fuel ratio which will also contribute to poor NO performance.
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Effects of Aging on Frictional Properties of Fuel Efficient Engine Oils

Ford Motor Co.-Milton D. Johnson, Ronald K. Jensen, Erin M. Clausing, Kurt Schriewer, Stefan Korcek
Published 1995-10-01 by SAE International in United States
Obtaining the maximum benefits from advanced fuel efficient engine oils will require that those oils not only provide fuel efficiency when new but also throughout the service interval for the oil. The effects of laboratory and engine aging on the ability of an oil containing a molybdenum dialkyldithiocarbamate (MoDTC) additive to provide reduced friction have been investigated. Results of these studies show that the friction reducing capability of this oil, as measured in a laboratory test, was lost prior to depletion of the MoDTC. Interactions between MoDTC and other additives were found to be important with regard to providing friction reduction. Implications for development of advanced oils that will provide lasting fuel efficiency benefits are discussed.
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Improving the Fuel Economy of Stoichiometrically Fuelled S.I. Engines by Means of EGR and Enhanced Ignition - A Comparison of Gasoline, Methanol and Natural Gas

Royal Military College of Canada-M. F. Bardon
Thermotech Engineering-G. R. Neame, D. P. Gardiner, R. W. Mallory, V. K. Rao
Published 1995-10-01 by SAE International in United States
This paper describes an experimental study in which the potential for fuel economy improvements with EGR was investigated using an automotive V6 engine. Steady state engine dynamometer tests were run at 2000 rpm and 200 kPa Brake Mean Effective Pressure (BMEP). The engine was fuelled with gasoline, methanol or natural gas. Plasma jet ignition was evaluated as a means of improving EGR tolerance.EGR tolerance with methanol was found to be better than with gasoline, while natural gas showed the poorest EGR tolerance. Plasma jet ignition extended EGR limits for all three fuels. Fuel economy benefits were realized with natural gas and gasoline at low EGR rates and without EGR but plasma jet ignition provided no improvements with methanol until over 10% EGR was used.Plasma jet ignition made stable operation possible with methanol at 40% EGR, where fuel economy improvements were ultimately limited by the slow burning associated with the high EGR rate. Both slow burning and high cyclic variation affected gasoline at high EGR rates, while stability limits to spark advance with natural gas caused…
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Fast Light-Off of Underbody Catalysts Using Exhaust Gas Ignition (EGI)

Cambustion Ltd.-G. Inman
Ford Motor Co., Ltd.-D. Eade, R. G. Hurley, B. Rutter
Published 1995-10-01 by SAE International in United States
The rapid heating of an under-body catalyst after cold start by combustion of rich engine products with added secondary air is described. The results of initial durability studies including spark plug fouling, oil dilution and thermal shock are presented, together with emissions performance and a mileage accumulation study. Also discussed are failure mode assessment and the system tolerance to anticipated open-loop errors and real-world driving scenarios.
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In Cylinder Augmented Mixing Through Controlled Gaseous Jet Injection

University of Wisconsin-Madison-C. Y. Choi, David E. Foster
Published 1995-10-01 by SAE International in United States
An investigation was performed on a direct injection diesel engine equipped with a gaseous injector to determine the effects of augmented mixing on emission characteristics. The gaseous injector introduced a jet of gas of particular composition in the cylinder during the latter portion of diesel combustion. This injector was controlled to inject the gas at specific engine timings and at various injection pressures.Engine experiments were done on a LABECO/TACOM single cylinder, direct injected, 1.2 liter, four stroke diesel engine. This engine was operated at 1500 rpm at an equivalence ratio of 0.5 with simulated turbocharging. The fuel injection timing was changed for some cases to accommodate the gaseous injection.Exhaust particulate emissions were measured with a mini-dilution tunnel. All other emissions data were measured on a REGA 7000 Real-Time Exhaust Gas Analyzer Fourier Transform Infrared (FT-IR) system.Industrial grade nitrogen was injected at high pressures and at various crank angles to observe the nitrogen's effects on emissions under different operating conditions. For an advanced diesel fuel injection timing, particulate emissions decreased to a minimum then increased as…
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Spark Anemometry of Bulk Gas Velocity at the Plug Gap of a Firing Engine

Ford Motor Co.-Richard W. Anderson
University of Michigan-Jaehong Kim
Published 1995-10-01 by SAE International in United States
The objective of the present work was to investigate a rapid method of obtaining the convection velocity of the bulk gas near the spark plug gap of a firing engine at the time of ignition. To accomplish this, a simple model was developed which utilized both the secondary current and voltage signals, from a conventional spark discharge. The model assumed the spark path was elongated in a rectangular U-shape by the flow. Based on experimentally measured electrical signals the mean convection velocity was computed. The convection velocity calculated by the model first needed calibration which was accomplished with a bench test that used a hot wire anemometer. The technique has a weak correlation at low velocities of 1-2 m/s, but correlates well at higher velocities up to 15 m/s. Although the accuracy of prediction by the technique is moderate, it is shown to be suitable for rapidly studying the bulk flow velocity near the plug gap in an operating engine without modification of the combustion system. It is also shown to favorably compare with data…
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Evaluations of Current Natural Gas Vehicle Technology Exhaust Emissions at Various Operating Temperatures

Environment Canada-Peter Howes, Greg Rideout
Published 1995-10-01 by SAE International in United States
As more stringent vehicle emission standards are introduced worldwide, there is an increased need to provide a thorough assessment of the environmental impact of alternative fuels. With the advent of CNG as a viable transportation fuel, the development of advanced computer controlled fuel delivery systems is imperative in order to ensure acceptable emission performance. At present, the majority of light and medium duty engines operating on natural gas are primarily gasoline automotive engines which have been retrofitted to allow for the use of CNG.The Mobile Sources Emissions Division of Environment Canada and the Canadian Gas Association have conducted a joint test program in order to develop a database of exhaust emissions from vehicles typically converted for operation on either gasoline or natural gas at various operating temperatures. The four light duty trucks selected for the program represented current commercially available natural gas fuel metering technologies designed for bi-fuel mode applications utilizing computer controlled electronic feedback fuel injection. Gaseous tailpipe exhaust measurements of carbon monoxide, oxides of nitrogen, carbon dioxide, methane, non-methane hydrocarbons, and aldehyde/ketones were…
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The Development of Driveability Index and the Effects of Gasoline Volatility on Engine Performance

Nippon Oil Co., Ltd.-Gen Shibata, Tatsuo Omata
Nissan Motor Co., Ltd.-Tohru Isoda, Kyoji Hosono, Kiyotaka Nakamura, Jun Tsuneishi, Haruhiko Kawano
Published 1995-10-01 by SAE International in United States
To reduce engine exhaust emissions, we have had to deal with this global environmental problem from the fuel side by introducing oxygenated fuels, reducing the RVP and using low aromatics. But when we change the fuel components and distillation, we must take note about how these affect the engine driveability.We have used T50, T90, RVP and so on as the fuel index up to the present. It is possible to characterize the fuel from one aspect, but these indexes don't always represent the real feature of the fuel.In this paper we propose a New Driveability Index (here in after referred to as NDI) that is more realistic and accurate than the other fuel indexes. We used a 1600cc DOHC L4 MPI type engine. We used Model Gasolines and Market Gasolines, see Appendix(1), (2) and (3), and tested them according to the Excess Air Ratio Response Test Method (here in after referred to as λ-R Test) that was suggested in SAE paper #930375, and we calculated the NDI statistically. This NDI is a function of the…
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Influence of Piston Ring Gaps on Lubricating Oil Flow into the Combustion Chamber

Meijo Univ.-Kohei Nakashima, Soichi Ishihara
Teikoku Piston Ring Co., Ltd.-Keiichi Urano
Published 1995-10-01 by SAE International in United States
The authors have utilized a modified automobile engine with a transparent glass cylinder, which was driven by an electric motor. The effects of the positions of the piston ring gaps, the end clearance size and the shape of the piston ring gaps on the lubricating oil flow were examined using the modified engine.The results indicate that the main stream of the lubricating oil flow goes from the lower ring gap to the upper ring gap in all of the positions of the piston ring gaps and that the position of the oil ring upper side rail gap has a great influence on the lubricating oil flow. We have also found that the lubricating oil flow is reduced by up to 26 % by utilizing the oil ring side rails with the optimized upper and lower side rail gaps as compared to the standard end clearance (standard production tolerances) and that the lubricating oil flow is reduced by up to 69 % utilizing the top ring with the special joint (triangle step joint) as compared to…
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