Fuel additive and method for improving combustion

Abstract

A fuel additive for addition in a vapor phase to a fuel such as gasoline in the air/fuel mixing zone of an internal combustion engine for increasing combustion efficiency in the engine while reducing the amount of gaseous pollutant emissions. BACKGROUND OF THE INVENTION The field of this invention is fuel additives for fuels used in internal combustion engines. It has been recognized in the past that liquid fuels for internal combustion engines, such as gasoline, can be improved by the inclusion in the liquid fuel of an alcohol with water and also other additives, examples of which are found in U.S. Pat. Nos. 1,412,233; 1,469,053; 1,474,983; 1,504,837; and 1,622,572. In more recent years, it was suggested in U.S. Pat. No. 2,789,891 that a gasoline fuel system conditioner should contain an alcohol without water but with a lubricating oil and other additives, which conditioner would be impossible to vaporize properly for vapor phase addition, and is added to the fuel in liquid form. SUMMARY OF THE INVENTION The present invention relates to a new and improved fuel additive which is added as a vapor to a fuel such as gasoline in the air/fuel mixing chamber of an internal combustion engine. The fuel additive includes an alcohol and water and preferably other selected additives, all of which are vaporizable in a blend for vapor phase addition to the engine fuel intake system. In the preferred embodiment, the fuel additive of this invention in a concentration of from 0.2 to 1.2 volume percent of the fuel, which amount is significantly small as compared to the amount of fuel while obtaining the advantages over the prior art of improved combustion efficiency, reduced gaseous pollutant emissions and volatility.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The fuel additive of this invention is a chemical blend which is injected as a homogeneous vapor into the fuel intake system of an internal combustion engine using air as a carrier gas. It has been discovered that by the addition of the fuel additive of this invention as such vapor mixture to the air/fuel mixing zone of the internal combustion engine, many advantages are produced, among which are increased combustion efficiency in the engine, reduced gaseous pollutant emissions and volatility of the fuel additive. The quantity of the fuel additive required using the method of this invention is extremely low and therefore such additive is economical. In the preferred form of the invention, the additive of this invention is added as a vapor in an amount of about 8 to about 45 cubic centimeters per gallon of fuel. Stated differently, the concentration of the fuel additive of this invention with respect to the gasoline or other primary fuel is from 0.2 to about 1.2% by volume.

The principal components of the fuel additive of this invention are an alcohol, preferably methanol, and water. When the alcohol and water are the only components of the fuel additive of this invention, the alcohol is present in an amount from about 20 to about 60% by volume (at 60.degree.F.), and the water is present in an amount of from about 80 to about 40% by volume. More precisely, the preferred volume percentages of the fuel additive are about 40% alcohol and aboout 60% water by volume.

The fuel additive is added to the fuel/air mixture as previously explained and the optimum amount which is added is about 20 cubic centimeters per gallon of the gasoline or other internal combustion fuel. With such method of this invention, employing the fuel additive of this invention, the combustion efficiency is increased approximately 12% and hydrocarbon pollutant emissions are reduced about 70%.

To further optimize the fuel additive of this invention, on the basis of ignition temperature, limits of flammability, flash point, latent heat of vaporization, molar heat release, and volatility, the fuel additive preferably includes other components such as aliphatic ketones, higher molecular weight alcohols, and aromatic solvents, in the preferred mixture set forth below:

Component Volume % (60.degree.F) Preferred Range ______________________________________ Methanol 53.8 30 - 65 Isopropanol 16.9 10 - 20 Methyl Ethyl Ketone 14.9 12 - 18 Toluene 6.9 4 - 12 Water 7.5 0 - 45 ______________________________________

Instead of methanol as the alcohol in the above composition, ethanol may be used with substantially the same results with respect to combustion efficiency, but with a reduced decrease in the pollutant emissions. Other higher molecular weight alcohols such as n-butanol, isobutanol, and the pentanols could be used in place of the isopropanol but with a decreased vaporization of the water constituents. Several aromatics such as zylene, benzene, or phenol could be used in place of toluene listed in the above example. However, the toluene is preferred because of its limits of flammability and flash point being more satisfactory in the blend. Other aliphatic ketones such as acetone, methyl proplyl ketone, or diethyl ketone could be used instead of the methyl ethyl ketone in the above example of the fuel additive of this invention.

It should be noted that all of the above additives are capable of being readily vaporized with the alcohol and the water. Such volatility is extremely important in producing the vapor of the fuel additive of this invention for use in carrying out the method of this invention by introducing same into the fuel/air mixing zone of the internal combustion engine. Additionally, the preferred mixture of this invention is capable of being vaporized at a constant vapor composition, which means that the mol fraction ratio of the components remain essentially constant. This is also important in providing consistently improved engine operation as the additive is being used.

Claims

I claim:

1. A fuel additive for adding in a vapor phase to fuel at the fuel intake to an internal combustion engine, consisting essentially of a homogeneous mixture of:

about 20 to about 65 percent by volume at 60.degree.F. of a low molecular weight aliphatic alcohol;

with the balance being water and additional additives compatible with said alcohol and vaporizable at approximately the same temperature in the mixture therewith;

said alcohol being methanol present in an amount of from about 30 to about 65 percent by volume of the additive; and

said balance consists of:

about 10 to about 20% by volume of isopropanol;

about 12 to 18 percent by volume of methyl ethyl ketone;

about 4 to about 12 percent by volume of an aromatic selected from the group consisting of toluene, xylene, benzene and phenol; and

with the rest being water.

2. A method of improving fuel combustion in an internal combustion engine wherein fuel, air and a vapor additive are mixed for combustion, comprising the steps of:

vaporizing a fuel additive using air to serve as a carrier for said additive in the vapor phase;

introducing said vapor to fuel and air mixed in the air-fuel mixing zone of the internal combustion engine; and

said fuel additive consisting essentially of:

about 20 to about 65 percent by volume at 60.degree.F. of a low molecular weight alcohol;

with the balance being water and additional additives compatible with said alcohol and vaporizable at approximately the same temperature in mixture therewith;

said alcohol being methanol present in an amount of from about 30 to about 65 percent by volume of the additive; and

said balance consists of:

about 10 to about 20 percent by volume of isopropanol;

about 12 to 18 percent by volume of methyl ethyl ketone;

about 4 to about 12 percent by volume of an aromatic selected from the group consisting of toluene, xylene, benzene and phenol; and

with the rest being water.

3. The method set forth in claim 2, wherein:

the fuel additive is added in a vapor phase in an amount of about 0.2 to about 1.2 percent by volume of the total of the fuel.