US 2096218 A
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Patented Oct. 19, 1937 UNITED STATES LIQUID FUEL Vanderveer Voorhces, Hammond, Ind., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing.
This invention relates to an improvement in fuels for internal combustion engines and more particularly fuels for engines of the direct injection type wherein the fuel is forced, under high 5 pressure, directly into the combustion zone. Examples of such engines are the well-known Diesel and semi-Diesel engines employing either the high pressure fuel system or the injection pump system.
In the operation of these engines, especially with the lighter grades of distillate fuel oils such as are commonly used for engines of the high speed type, a great deal of difiiculty has been encountered with erosion of fuel valves and fuel 15 pumps. This difliculty has been traced to the low viscosity of the fuel, especially at the somewhat elevated temperatures at which it is used, under which conditions the rubbing metal surfaces of pump plungers and valves rapidly be- 20 come worn. Even a slight amount of wear of these parts of the engine leads to serious consequences because of the very small clearances between operating parts required in handling and imecting the minute quantities of fuel necessary 25 for the operation of these engines. Thus, in a muiti-cylinder high speed, automotive Diesel engine the amount of fuel injected per stroke is only a small fraction of a cubic centimeter and consequently a verylittle wear in the fuel valve or pump results in erratic operation of the engine by varying the volume of the fuel injected per stroke.
Attempts to overcome this difiiculty have heretofore been made by increasing the viscosity of the fuel employed. However, any benefit obtained by so doing is more than offset by improper distribution and unsatisfactory combustion of the more viscous fuel as a result of its correspondingly decreased volatility. I have now discovered a means by which the viscosity of the fuel may be significantly increased while at the same time maintaining substantially the same volatility and combustion characteristics. 'In fact, I am even able to increase the volatility beyond that previously employed and simultaneously increase the viscosity, with resulting improvement in lubrication of fuel pumps and valves as hereinafter described.
My new Diesel fuel oil comprises a distillate fuel of the desired volatility and combustion characteristics, together with a small amount of a special viscosity producing agent which is a resinous product produced by the polymerization of olefin hydrocarbons. The resinous product which I employ is a non-crystalline plastic hydrocarbon material, soluble in hydrocarbon oils and. plastic at all ordinary temperatures, from well below F. to temperatures above 300 F. and even as high as 400 F. where the material still retains its body or viscosity to a large degree.
Application October 31, 1935, Serial No. 47,609
It is characterized by light color, high stability and high molecular weight, usually between 1,000 and 12,000. The empirical formula of the resin is substantially CnHin and on heating to decom position temperature it depolymerizes without the formation of undesirable coke and other residues.
The plastic resin may be most conveniently made by polymerization of liquid isobutylene at low temperatures, below 0 F. and preferably -40 to l00 F. In carrying out the polymerization, a suitable catalyst is necessary and boron fluoride or aluminum chloride may be used for this purpose, the amount required being from about 0.1 to If boron fluoride, which is a gas, is used it may be conveniently bubbled into the cold isobutylene while the latter is rapidly agitated. The reaction requires from several minutes to a half hour, the isobutylene being converted to a plastic mass at the end of that time. For convenience in handling and agitating it is usually desired to employ a diluent, which may conveniently be hexane, butane, propane, or in the case of very low temperature operations, liquid ethane. The
.diluent may be readily removed from the product by evaporation, preferably after the product has been neutralized and washed to remove the catalyst. If desired, the isobutylene may be polymerized directly in the presence of the distillate fuel oil in which it is desired to be used.
Other oleflns besides isobutylene may be employed as starting materials for making the plastic resin; for example, normal butylene, amylene, hexylene and mixed olefinic hydrocarbons and saturated hydrocarbons condensed from cracking still gases, preferably those boiling in the range of 20 to 50 F.
The amount of plastic resin required to make the product of this invention may be from 1 to of the weight of the oil treated and amounts of about 2 to 5% are usually preferred. A suitable fuel oil employed for the purpose possessed the following distillation characteristics as determined by A. S. T. M. distillation:
This oil was blended with 2% and 5% of a plasticresin from isobutylene polymerization and tested with 9. Diesel engine of the high speed type. The
non-volatile plastic resin did not interfere in any way with the combustion of the fuel in the engine, and improved lubrication of the fuel valve was obtained. The viscosity of the fuel was increased from 39 seconds Saybolt at 100 F. to 42.2 seconds Saybolt at 100 F. by the addition of 2% of the resin and to 48.3 seconds Saybolt at 100 F. by the addition of 5% of the resin. The cetene number of the fuel which was 64 before the addition of the resin, remained unchanged.
The amount of resin added will vary with the initial viscosity and volatility of the fuel. Thus a light, low boiling fuel will require more resin to raise the viscosity to the desired extent. It is preferred to increase the viscosity above seconds Saybolt, and a range of 45 to seconds Saybolt is desirable. employed however.
As previously mentioned. the use of the plastic resin in Diesel fuels is especially applicable to the Higher viscosities may be lighter fuels such as petroleum distillate fuel having the following characteristics:
Flash point -F Pour point do 35 Distillation A. S. T. M. 10% point F 395 point do 450 Maximum .do 490 Viscosity-Saybolt at F sec 32 The term plastic hydrocarbon resin asused 'point below about 650 F., said oils tending to cause such excessive wear on the fuel pump and ..valves as to render them inoperative in worn condition for such fuels, comprising adding to the said light Diesel fuel oil suflicient isobutylene polymer, between 1 and 10%, to raise the viscosity to a pump and valve sealing and lubricating consistency without substantially adversely affecting the combustion characteristics of the said light Diesel fuel oil, and then injecting the fuel into said engine through said pump.
2. The method of claim 1 wherein the viscosity of the said light Diesel fuel oil before the addition of isobutylene polymer is about 32 to 39 seconds Saybolt at 100 F.
3. The method of claim 1 wherein the said isobutylene polymer is a plastic hydrocarbon resulting from the polymerization of isobutylene at low temperatures below 0 F. in the presence of a metal halide catalyst.
I v CERTIFICATE OF CORRECTION. v t Patent No, 2,096,218. October 19, 1957.
VANDERVEER VOORHEES It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 21 in the table, for "55" read 55; and that thesaid llet ters Patent should be read with this correction therein that the same may conform to; the record of the case .in the Patent Office.
Signed and sealed this 16th day of November, A. D. 1957.
Henry Van Arsdale,
(Seal). Acting Commissioner of Patents.