Internal-combustion engines – Miscellaneous – Fuels – lubricants and additives
Reexamination Certificate
2000-10-16
2003-02-25
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Miscellaneous
Fuels, lubricants and additives
Reexamination Certificate
active
06523503
ABSTRACT:
TECHNICAL FIELD
The invention generally relates to internal combustion engines. More specifically, the invention relates to fuels, lubricants and additives. Another aspect of the invention generally relates to combustion and more specifically to processes of combustion operation, especially to feeding a flame modifying additive. Specifically disclosed is a method for providing and maintaining a catalytically active surface on combustion-exposed parts of an internal combustion engine, such as fire deck, valve faces and piston faces, so that combustion efficiency is improved and harmful exhaust emissions are reduced. The invention is particularly applicable to improving combustion in “green” engines, such as engines that are new, recently rebuilt, or that have low operating hours.
BACKGROUND ART
Worldwide emphasis on reducing global warming and reducing pollution mandates improved efficiency in combustion processes, which can be defined as improved fuel efficiency coupled with reduced emission of pollutants such as oxides of nitrogen (NOx). Ferrocene is known to improve combustion efficiency in burners, for example from U.S. Pat. No. 3,341,311. In quantitative terms, it has been reported that ferrocene can produce a 10% improvement in fuel efficiency. However, such results have not been uniformly achieved, especially with modern design, low emission engines, both new and after they have been in service for an extended time. Such modern engines, i.e., newer than 1995, are designed and constructed to consume less lube oil. In addition, they use cleaner fuels, lower in aromatic and sulfur content. All of these factors combine to minimize combustion chamber deposits. While modern engines running on modern fuels emit fewer pollutants than older engines, the technology has compromised the effective use of ferrocene to achieve still greater improvements.
In older literature, ferrocene was tested in diesel engines and showed effectiveness as a fuel additive for conditioning the engines to achieve improved fuel economy and reduced emissions. U.S. Pat. No. 4,389,220 to Kracklauer discloses a two-stage method of conditioning a diesel engine, resulting in reduced pollutant emissions and increased efficiency in fuel combustion. According to this patent, an initial high dosage of ferrocene, such as 20-30 ppm, in the diesel fuel can eliminate carbon deposits from the combustion chambers and deposit a layer of catalytic iron oxide on the combustion surfaces. Thereafter, a lower dosage of ferrocene, such as 10-15 ppm, maintains the catalytic iron oxide coating. It is considered undesirable to maintain the initial high concentration of ferrocene in diesel fuel, as this will lead to detrimental combustion modifications, minimizing or eliminating the beneficial effects of the catalytic iron oxide wall coating.
Older literature also shows that ferrocene can be effective in gasoline engines by improving the octane rating of treated fuel. In this way, ferrocene can reduce certain exhaust emissions and decrease fuel consumption in gasoline powered vehicles. Schug, K. P., Guttann, H. J., Preuss, A. W., and Schadlich, K.,
Effects of Ferrocene as a Gasoline Additive on Exhaust Emissions and Fuel Consumption of Catalyst Equipped Vehicles
, SAE Technical Paper Series, 1990, paper number 900154. The method disclosed in this article and in related U.S. Pat. No. 4,955,331 is the simple addition of ferrocene to fuel as a method of achieving improvements in efficiency and emissions. This technology recently was tested with a modern engine using modern fuels. The test vehicle was a 1998 Dodge Intrepid with 29,500 miles on the odometer before testing started. Three fuel fills without ferrocene, corresponding to over 882 miles of operation, yielded a 27.7 mpg average fuel efficiency. Subsequently, four fills with ferrocene treatment, corresponding to 1170 miles, yielded a 26.4 mpg efficiency. These results suggest that simple addition of ferrocene to fuel as taught by Schug et al is not an effective method of improving combustion in such a gasoline fueled modern engine.
Other tests show that ferrocene does not produce combustion improvement in every case, especially when an engine is of modern design. A recent test with a 1998 Detroit Diesel Series 60 engine followed the process of U.S. Pat. No. 4,389,220 after the engine had accumulated 350 hours of break-in operation. Specifically, the engine was operated for 5 hours at a 125 ppmw dose of ferrocene to the fuel, followed by switching to a 25 ppmw dose for emissions testing. The test results showed no change in the fuel efficiency or NOx emissions of the engine. Hence, the simple staged addition of ferrocene to fuel as disclosed in U.S. Pat. No. 4,389,220 was not effective to improve performance of this modern design diesel engine.
Another approach to improved combustion is by the catalytic coating of combustion chambers prior to assembly and operation of the engine. In work described in Gaffney et al. “Soot Reduction in Diesel Engines: A Chemical Approach,” a diesel combustion chamber coated with platinum demonstrated a 40% particulate emission reduction. Unfortunately, this combustion catalytic effect was fully lost after 50 hours of normal engine operation.
Siegia and Plee, “Heterogeneous Catalysis in the Diesel Combustion Chamber,” attempted to duplicate Gaffney's result with a new engine having a platinum coating. However, no catalytic activity of any kind was found, despite use of the same platinum coating. This series of experiments showed two of four unresolved problems with platinum coatings: 1) the catalytic effects are non durable; and 2) the catalytic effects are not reproducible. The remaining two unresolved problems with platinum are high cost and the toxicity of platinum as an exhaust pollutant, itself.
Other ferrocene related technology is disclosed in U.S. Pat. No. 4,612,880 to Brass et al., which discloses a method of controlling octane requirement increase in internal combustion engines. This method requires introduction of a gasoline soluble iron compound such as dicyclopentadienyl iron (ferrocene) together with a carboxylic acid or ester derivative thereof, into a combustion chamber coated with alumina or zirconia with a carbon gassification catalyst dispersed therein. However, this technology involving base metal surface catalysis is not effective for the process of this invention, as shown in the test reported at Table 1, 5b2 of this document. In addition, the disclosed catalyst compositions are prepared from soap or salt precursors and used in thick coatings, which deteriorate combustion efficiency.
SAE Paper 910461 discloses a thermal barrier coating that produces increased combustion efficiency of 1.7%. An undesirable effect of this thermal burner coating is an increase in NOx output, which is unacceptable in modern engines facing severe emission control constraints.
It would be desirable to provide improved combustion efficiency by a method or coating that can be made effective even when an engine is “green,” or has few operating hours, such that the combustion surfaces have not yet developed substantial combustion deposits.
Similarly, it would be desirable to provide the previously known benefits of ferrocene usage in engines of modern design, i.e., post 1995, having low consumption of lube oil and adapted to use modern fuels with lower aromatic and sulfur contents.
Further, it would be desirable to develop a durable or maintainable coating for the combustion chamber that can maintain the combustion facing surfaces at catalytically active temperatures, despite the attachment of the durable insulating coating on the combustion facing surfaces to a coolant-cooled wall surface.
In combination with providing a catalytically active combustion chamber surface for improved combustion efficiency, it would be desirable to provide a device or system to continuously maintain the active nature of the surface.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly describ
Kamen Noah P.
Rost Kyle W.
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