US2872303A - Anti-stalling gasoline agent - Google Patents

Description

United States Patent ANTI-STALLING GASOLINE AGENT Theodore R. Donlan, Union, N. J., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application May 18, 1955 Serial No. 509,411

6 Claims. (Cl. 44-72) The present invention is concerned with a motor fuel composition adapted to be carbureted and to provide improved motor operation under cool and moist operating conditions. The motor fuel composition of the presentinvention comprises gasoline, which is a hydrocarbon mixture boiling within the usual gasoline boiling range of 50 .F. to 450 F. and which contains as an ingredient a very small percentage of a volatile primary amino alkanolhaving the functional groups separated by not more than one carbon atom in the longest chain of the alkyl group. The preferred example of said amino-alkanol is 2-amino-2-methyl-l-propanol. In addition, the fuel compositionsof the present invention may contain other additives such as solvent oil, anti-detonants such as lead alkyls, dyes, gum inhibitors, oxidation inhibitors, and the like. Gasoline suitable for use in accordance with the present invention is fully defined in United States Specifications, Federal VV-M-561a and Military MIL-G-3056A and MILF-5572l.

The novel fuel compositions of the present invention are intended to overcome certain difiiculties encountered inthe operation of automotive, marine, stationary, and airplane internal combustion engines. The difiiculties re sult in loss of power, and frequently cause the engine to stall under idling conditions. This loss of power and stalling is more frequentlyencountered under weather conditions in which a relatively high humidity exists, and the temperature is below about 60 F. and above about 30 F.

This problem has been known for some years. Car owners, particularly in the colder areas of the United States, have noted that during cool, wet weather their cars give poor idling performance in that their engines repeatedly stall. The difiiculty is not special to any one car but is encountered in all types of cars employing various types of carburetors.

The magnitude of this difiiculty is pointed up by a survey conducted in the New Jersey area based on the experiences of 300 car owners driving twenty different car models, during the fall and winter period. These cars employed the winter grades of regular and premium commercial gasolines. Table I gives a summary of the results obtained, showing the substantial number of stalls encountered in the operation of the cars under the indicated conditions.

i TABLE I No. of Complaints of Two Stalls or more (per 100 cars) Atmospheric Conditions:

Temperature, F 32 35 37 52 56 7 Relative Humidity, Per- 52 70 96 100 9G cent. Weather Clear Over- Lt. Heavy Rain cast Rain Rain Observations:

Winter Regular Users- 15 20 21 7 Winter Premium Users. 6 38 40 42 2 "ice The above figures serve to show the magnitude of the problem of engine stalling under cool and humid weather conditions. Furthermore, in recent years this problem has become of increased importance due to automotive changes. Newer cars are not provided with a manual throttle so that car owners are no longer able to increase the idle speed during the warm-up period to prevent stalling. Also the idle speed of cars with automatic transmissions is rather critical during the warm-up period and the fastest idle which may be used without creeping of the vehicle is rather low, thereby increasing the criticality of stalling conditions. Finally, stalling of a car with automatic transmission frequently does not occur until the driver is about ready to accelerate, so that just at this most inconvenient time it is necessary to shift the transmission to neutral position, restart the engine, and shift back into drive position. Another factor affecting the magnitude of stalling difficulties relates to the volatility of the fuels now provided for automotive use. The volatility of commercial fuels over a period of years has been increased sufiiciently to increase stalling difficulties as will be brought out herein. This problem has been recognized and various additives suggested such as dis closed in U. S. 2,701,754, U. S. 2,600,113, U. S. 2,599,338 and U. S. 2,579,692.

As pointed out in the art, it has been determined that the cause of repeated engine stalling in cool, humid weather is the formation of ice in the carburetor of the engine. On a cool, moist day, gasoline evaporating in the carburetor produces a refrigerating eifect which causes the moisture present in the air entering the carburetor to condense and freeze. Normal fuel vaporization within the carburetor may result in cooling the metal parts of the carburetor to a temperature as low as 50 F. below that of the entering air. Thus, before the time of complete engine and radiator warm-up, this drop in tem perature may cause, under the conditions specified, formation of ice in the carburetor. Ice formation also probably occurs most readily under conditions of light load operation. The result is that after a period of light load operation, when the throttle is closed to the idle position, ice already forms on the throttle plate and ad jacent walls, plus ice which then forms, restricts the narrow air openings to cause engine stalling.

This problem of ice formation is also encountered in aggravated form in one case of those engines employing carburetors which have small Venturi diameters, especially when the Venturi tube is insulated from the casting of the body of the carburetor. It has been found that such carburetors having a Venturi diameter of 21 millimeters or less, are particularly subject to ice formation, causing severe throttling of the fuel flow in the Venturi itself.

Also as pointed out in prior art, tests show that stalling difiiculties due to ice formation in the carburetor are not encountered below about 30 F., nor above about 60 F. when employing gasoline having conventional volatility characteristics. Similarly, these tests have demonstrated that stalling is only usually encountered when the humidity is in excess of about 65%.

Another factor having a bearing on the formation of ice in the carburetor, is the volatility of the fuel employed. To determine this effect laboratory cold room tests were conducted to evaluate the stalling characteristics, during engine warm-up, of a number of fuels varying in volatility. In these tests a 1947 Chrysler car was installed in a room equipped with temperature and humidity controls. While the temperature and humidity were maintained at particular levels, the stalling characteristics were determined during the warm-up period. The procedure employed was to start the car and to then immediately raise the engine speed to 1500 R. P. M. This speed was maintained for 30 seconds, after which the engine was allowed to idle for 15 seconds. If the engine stalled before 15 seconds had expired, the car was again started and raised to a speed of 1500 R. P; M. for 30seconds, while if stalling did not occur, the speed was immediately increased to 1500 R. P. M. after the 15 second idling time. The alternate cycles of 30 seconds at 1500 R. P. M. followed by 15 seconds at idling were repeated until the engine was completely warmed up. The number of stalls encountered during this procedure, and up to the time of complete engine warm-up were then recorded. Tests were conducted at 40 F. and at a relative humidity of 100% cmploying three fuels of varying volatilities. The most volatile fuel was a premium grade of commercial gasoline having a 10% ASTM (method D-86) distillation point of 110 F., a 50% point of 190 F., and a 90% point of 294 F. It was found that this fuel resulted in about 14 or 15 stalls during warm-up. A medium volatility fuel was also tested, consisting of a regular grade commercial gasoline having ASTM distillation characteristics such that 10% distilled at 121 F., 50% distilled at 220 F., and 90% distilled at 342 F. The number of stalls encountered with this fuel were 11. Finally a low volatility gasoline was subjected to the same test procedure. The gasoline had ASTM distillation 10, 50, and 90% points, at 126 F, 270 F., and 387 F. It was found that stalls were encountered with this fuel.

As indicated by these data, carburetor icing is related to the volatility of the fuel employed. Thus, the least volatile fuel tested above, having a 50% distillation point of 270 F., only resulted in 5 stalls, while the highest volatility fuel, having a 50% distillation point of 190 F., resulted in 15 stalls. Extrapolating these data as to the volatility of the fuel, it appears that a wholly hydrocarbon fuel having a volatility such that the ASTM 50% distillation point is 310 F, or higher by method D86 would not be subject to stalling difficulties during warm-up. It must be appreciated, however, that a fuel having ASTM distillation characteristics of this nature would not be desirable as regards warm-up time, cold engine acceleration, economy and crankcase dilution. Also, it should be appreciated that even when complete stalling does not occur there may be a marked loss of power output due to icing. This is particularly serious in the case of aviation engines.

It has now been discovered that if a relatively small quantity of a specially selected compound of the class of amin'o-alkanols is added to the fuel, the tendency for a gasoline engine to stall is markedly reduced. The preferred compound in the specially selected group of compounds is 2-amino, 2methyl, 1-propanol and the range of effective concentrations to be used in accordance with this invention is from about 0.01% by volume to 0.4% by volume. The preferred range is from about 0.025% to 0.05%. in addition to functioning as an anti-icing agent, Z-amino, Z-methyl, l-propanol also acts as a rust preventive.

The selected group of compounds suitable for use in accordance with the present invention has the generic formula:

wherein R is an alkyl radical having from 1 to 3 carbon atoms, 11 is zero to one and R is a member of the Markush group of hydrogen and R; wherein also the amino group is primary itself but is attached to a tertiary carbon atom; and wherein the total number of carbon atoms is not less than 4 and not more than 9 and preferably not more than 6. R, of course, can be methyl, ethyl, propyl or isopropyl; and consequently R can be methyl, ethyl, propyl, isopropyl or an atom of hydrogen. The compounds of this group represented by the generic formula are primary-amino, tertiary-alkyl carbinols. They are added to gasoline in accordance with this invention in concentrations between 0.015 and 0.40% by volume. They are efi ective for preventing the formation of ice when the gasoline containing them is carbureted in the presence of cool, moist air; and for preventing the corrosion of metal containers of the liquid gasoline containing them.

The desirability of the limited group of primary-amino, tertiary-alkyl carbinols and particularly of 2-amino, 2- methyl, l-propanol for addition to motor fuels is readily apparent from the following data.

In this test a motor fuel of the type of premium grade leaded motor gasoline was used. It had the following volatility characteristics:

Reid vapor pressure 12.4 initial boiling point F 88 12.5% distillation point F 117 52.5% distillation point F 205 94.5% distillation point F 342 Final boiling point F 408 TABLE II Ami-icing eflect of Z-amino, Z-methyl, l-propanol Additive, Wt;., Percent Time to Icing, Seconds }a-vcrage 98.

all longer than 480.

The same range of concentrations between 0.015% and by volume, and preferably between 0.05% and 0.10% by volume, is effective in aviation gasoline consisting predominantly of branched parafiinic hydrocarbons and of no more than 20% by volume of aromatic hydrocarbons and having about 6.5 Reid vapor pressure, and a volatility characterized by 50% point of F. and end point of 320 F.

Specific examples of primary-amino, tertiary-alkyl carbinols suitable for adding to gasoline in accordance with this invention are:

2-m'ethyl-2-amino-l-propanol 2-ethyl-2-amino-1-propan0l 3-methyl-3 -amino-2-butanol 2,3-dimethyl-3-amino-2-butanol 3-methyl-3-amino-1-butanol 2,4-dimethyl-4-amino-2-pentano1 2,4,4-trirnethyl-2-amino-l-pentanol The gasoline to be used in accordance with this invention is the modern fuel for high compression automotive and aviation engines. The composition of the present invention prevents the accumulation of ice, which might be formed from the chilling of moist air by the vaporization of the fuel in the Venturi tube and on the throttle plate of the carburetor.

The characteristics of modern automotive gasoline are set forth in ASTM specifications for gasoline, D439-52T, and also in semi-annual Reports of Investigation (e. g. RI 4901) entitled National Motor Gasoline Survey by the United States Bureau of Mines. The maximum temperature permitted for the 50% point of the gasoline disper strip corrosion scale.

tillation in ASTM D439-52T is 284 F. The values for the temperature at the 50% point shown in the reports of the Bureau of Mines are considerably lower than the ermissible maximum and have trended lower, year by year, for many years.

The minimum octane number permitted in ASTM D439-52T is 78, and the actual octane numbers of commercial gasolines exceed that minimum. The actual octane numbers are generally higher than 80 and are sometimes as high as 98 Research octane number.

The high values of octane number are required because modern engines have high compression ratios of at least 7. To attain high octane numbers, tetraethyl lead is used as an anti-knock agent. It is used in concentrations up to 3 cc. per gallon. The presence of sulfur in the gasoline, and particularly of elemental sulfur, is antagonistic to the anti-knock effect of tetraethyl lead. This antagonism of reactive or corrosive forms of sulfur was fully described in 1949 in Industrial and Engineering Chemistry, vol. 41, pages 888 to 893 and 2722 to 2726. The ASTM specifications recognize the harm of corrosive sulfur by requiring that gasoline must pass a corrosion test with a rating no worse than No. 1 on the ASTM cop- By actual test it has been determined that in order to have a rating no worse than No. 1, the gasoline must contain less than one part of elemental sulfur per million parts of gasoline by weight; that is, less than 0.0001%.

The characteristics of modern aviation gasoline are set forth in ASTM specification D9l0-52T. The maximum temperature permitted for the 50% point of the gasoline distillation is 221 F., and the temperature for the 90% point must be between 257 F. and 275 F. The sum of the 10% and 50% points must be at least 307 F.; and since the R. V. P. must be below 7 p. s. i., and 10% point must be at most 158 F., the minimum temperature permitted for the 50% point by these indirect limitations is about 180 F. The minimum octane number permitted by these specifications is 80 by the Aviation Method. The content of tetraethyl lead specified is between 0.5 and 4.6 ml. per gallon; and, as in the case of the motor gasoline specifications, ASTM D910-52T also requires the aviation gasoline to pass the corrosion test with a rating no worse than No. 1 comparison standard.

What is claimed is:

1. A gasoline composition comprising a high quality gasoline base having an octane number greater than about 80, 2. Reid vapor pressure of at least about 7 p. s. i., an ASTM distillation point below about 310 F., and containing a small amount, sufiicient to improve the antistalling tendency of a gasoline engine, of a volatile primary amino alkanol having the structure wherein R is an alkyl radical having from 1 to 3 carbon atoms, n is zero to one and R is a member of the group consisting of hydrogen and R; wherein the amino group is primary itself but is attached to a tertiary carbon atom; and wherein the total number of carbon atoms is not less than 4 and not more than 9.

2. 'The composition as defined by claim 1 wherein the amount of amino alkanol is in the range from about 0.015 to 0.4% by volume.

3. A high quality gasoline composition comprising a base gasoline and a small amount of a compound of the following structure:

wherein R is an alkyl radical having from 1 to 3 carbon atoms, )1 is zero to one and R is a member of the group consisting of hydrogen and R; wherein the amino group is primary itself but is attached to a tertiary carbon atom; and wherein the total number of carbon atoms is not less than 4 and not more than 9.

4. The composition as defined by claim 3 wherein the amount of said compound present is in the range from about 0.015 to 0.4% by volume.

5. The composition as defined by claim 3 wherein the amount of said compound present is in the range from about .05 to 0.1% by volume.

6. The composition as defined by claim 3 wherein said compound comprises Z-amino, Z-methyl, 1-propanol.

References Cited in the file of this patent UNITED STATES PATENTS 1,668,022 Midgley May 1, 1928 1,843,942 Calcott et a1. Feb. 9, 1932 2,139,122 Hass Dec. 6, 1938 2,706,677 Duncan et a1. a Apr. 19, 1955 FOREIGN PATENTS 845,407 France Aug. 23, 1939

Claims (1)

1. A GASOLINE COMPOSITION COMPRISING A HIGH QUALITY GASOLINE BASE HAVING AN OCTANE NUMBER GREATER THAN ABOUT 80, A REID VAPOR PRESSURE OF AT LEAST ABOUT 7 P. S. I., AN ASTM DISTILLATION 50% POINT BELOW ABOUT 310* F., AND CONTAINING A SMALL AMOUNT, SUFFICIENT TO IMPROVE THE ANTISTALLLING TENDENCY OF A GASOLINE ENGINE, OF A VOLATILE PRIMARY AMINO ALKANOL HAVING THE STRUCTURE.