US2784160A

US2784160A - Otto cycle engine fuels and lubricants containing halohydrocarbon

Info

Publication number: US2784160A
Application number: US435945A
Authority: US
Inventors: Blaker Robert Hockman
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1954-06-10
Filing date: 1954-06-10
Publication date: 1957-03-05
Anticipated expiration: 1974-03-05

Description

OTTO CYCLE ENGINE FUELS AND LUBRICANTS CONTAINHQG HALOHYDROCARBON No Drawing. Application June 10, 1954, Serial No. 435,945

8 (Jlaims. (Cl. 25258) This invention relates to improvements in the operation of Otto cycle engines, to agents for improving such operation and, particularly, to improved fuels containing such agents for use in such engines. The build up of deposits in the combustion chambers of spark-ignition internal combustion engines of the Otto cycle type is known to increase the octane requirement of the engine. After many hours of operation, the engine octane requirement and the weight of deposits in the combustion chamber reach equilibrium values. As well as increasing octane requirement, the deposits can also be the cause of abnormal combustion phenomena such as preignition and post ignition.

An object of the present invention is to provide a group of agents which, when present in very small amounts in the combustion chamber of a spark-ignition engine of the Otto cycle type during the operation of such engine, will change the character of the deposits in such combustion chamber so as to reduce the octane, or preignition, requirement of the engine, and usually will decrease the amounts of such deposits. Another object is to provide an improved method for operating an Otto cycle engine which comprises introducing at least one of such agents into the combustion chamber of the engine during its operation. A further object is to provide improved fuels containing such agents, which fuels are particularly adapted for use in Otto cycle engines. A still further object is to provide improved crankcase oils containing one or more of such agents, which oils are particularly adapted for use in lubricating Otto cycle engines, especially the combustion chambers thereof, whereby they improve the operation of such engines. Other objects are to provide new compositions of matter and to advance the art. Still other objects will appear hereinafter.

The above and other objects may be accomplished in accordance with this invention which includes, as an improvement in the operation of an Otto cycle engine in which the fuel employed is a gasoline containing tetraethyl lead, the step of introducing into the combustion chamber of the engine during its operation from about 0.1% to about 2% by weight, based on the gasoline, of at least one halogenated fluorine-containing ethane of the group consisting of l-bromo-l,l-dichloro-2,2,2-trifluoroethane (BrClzC-CFs), 1,2-dibromo-1-chloro-1,2,2-trifluoroethane (BrClFC-CF2Br), and 1,l,2,2-tetrachloro- 1,2-difiuoroethane (ClzFC-CFClz); gasolines containing tetraethyl lead and such proportions of at least one of such halogenated fluorine-containing ethanes; and crankcase oils containing from about 2% to about by weight of at least one of such halogenated fluorine-containing ethanesthe gasolines and the crankcase oils which contain such halogenated fluorine-containing ethanes being new compositions of matter and constituing preferred means for introducing such compounds into the combustion chambers of the engines.

The term combustion chamber, as used here, includes all the portion of the cylinder above the piston,

It has been found that the presence of a very small 2,784,160 Patented Mar. 5

amount of one of the halogenated fluorine-containing ethanes of this invention in the combustion chamber of a spark-ignition internal combustion engine of the Otto cycle type, during the operation of'such engine with a gasoline containing tetraethyl lead, decreases to a significant extent theequilibrium octane requirement of the engine and usually the amounts of the combustion deposits in the combustion chamber; Such halogenated fluorine-containing ethanes appear to alter, in some unknown manner, the characteristics of the combustion deposits which are formed in the combustion chamber so as to materially decrease the harmful effects of such deposits on the combustion of the fuel in the combustion chamber, as well as frequently decreasing the amounts of such deposits. At the same time, such halogenated fluorine-containing ethanes do not appear to have any significant harmful effect on the desirable properties of the fuels or of the crankcase lubricants employed in such engines.

Also, under some circumstances, when the halogenated fluorine-containing ethanes of this invention are employed in gasoline containing tetraethyl lead, all or part of the conventional scavenging agents, such as ethylene dichlo ride and ethylene dibromide, can be omitted without deleteriously affecting engine performance.

The halogenated fluorine-containing ethanes of the present invention may be introduced into the combustion chamber of the engine by a variety of procedures. Usually, it is preferred to introduce them as solutions in the fuel for the engine, in which case, they will be present in the fuel in the desired concentration of from about 0.1% to about 2% by weight based on the gasoline.

The fuel may be any conventional gasoline, or. blended mixture of hydrocarbons having the characteristics of gasoline, which is suitable for use in the particular engine and which will also contain tetraethyl lead in the proportions to give to the fuel the octane number required by the particular engine. Such gasoline may contain antioxidants, coloring agents, and other adjuvants commonly employed therein. Such fuels and the requirements thereof for the different engines are well known and conventional and the specifications thereof are well Within the capabilities and knowledge of those skilled in the art.

The halogenated fluorine-containing ethanes of this invention may be mixed with tetraethyl lead, usually with the conventional scavenging agents, to provide a'n antiknock composition to be added to gasoline for producing the desired fuel, the proportion of the halogenated fluorine-containing ethane in such composition being that which will provide the desired concentration thereof in the finished fuel.

Another satisfactory mode of introducing the halogenated fluorine-containing ethanes into the combustion chamber of an engine is as a solution in the lubricating oil for the engine in a concentration of from about 2% to about 10% by weight, based on the oil, i. e. in the crankcase lubricating oil for the engine. In the operation of an engine, the crankcase oil enters the combustionchamher to lubricate the walls thereof and the parts operating therein. When the crankcase oil contains a halogenated fluorine-containing ethane of this invention, such halogenated fluorine-containing ethane is carried into the combustion chamber by the ,oil where it is effective to alter the character of the deposits in the combustion chamber so as to materially reduce the equilibrium octane requirement of the engine. 7

The crankcase lubricating oil will be that which is suitable for use with the particular engine andunder the conditions under which it is to be. operated in-the absence of the halogenated fluorine-containing ethane. It

may contain antioxidants, stabilizers, viscosity improving agents, dispersants and other adjuvants commonly employed in such oils. Such crankcase lubricating oils are well-known and conventional, and the selection thereof is within the capabilities of those skilled in the art and will bedependent upon the desire of the user of the engine and the requirements of the particular engine.

Another suitable mode of introducing the halogenated fluorine-containing ethanes into the combustion chamber of the engine is to inject them into the combustion chamher as fine streams or sprays independently of but simultaneously with the fuel. As so introduced, the halogenated fluorine-containing ethane may be in substantially pure form. However, because of the difiiculty of accurately controlling the feed of the small amounts required, it, preferably, will be diluted with or dissolved in a readily combustible organic liquid which is inert to the halogenated fluorine-containing ethane at moderately elevated temperatures, preferably normally liquid non-viscous hydrocarbons such asaliphatic hydrocarbons of from about 4 to about 16 carbon atoms, gasoline, kerosene, benzene, toluene and mixtures of two or more thereof. Since the halogenated fluorine-containing ethanes are quite stable and are inert to most organic liquids, a wide variety of such liquids may be used, including particularly ketones, ethers, alcoholes, etc. In such case, the halogenated fluofine-containing ethane will be in high concentration in the injected mixture or solution, the diluent or solvent being only that required to ensure easy measurement and control of the amount injected.

Means for injecting small amounts of combustion assistants and supplementary fuels into the combustion chambers of engines are well-known to those skilled in the art and are conventional. Such means are suitable for injecting the halogenated fluorine-containing ethanes of this invention, in pure or diluted form, into the combustion chamber of an engine by the last described procedure. v

In order to more clearly illustrate this invention, the preferred modes of carrying it into effect, and the advantageous results to be obtained thereby, the following examples and tests are given in which the halogenated fluorine-containing ethanes were tested by a variety of procedures in a variety of Otto cycle engines and their eifects on desirable properties of gasolines were determined:

TEST PROCEDURE I Tests were conducted in a Lauson model H-2 single cylinder engine mounted on a test stand with a 5 H. P. synchronous electric motor to absorb the output of the engine. This L-head engine has a compression ratio of 6.5 to 1 and a displacement of 14.89 cubic inches. The engine was operated under cyclic conditions involving three minutes of part load operation followed by one minute of operation under no load.

During the three minutes of part load, the engine was operated under the following conditions:

Speed R. P. M 1720 Spark advance E. T. C 20 Load B. H. P 1.0 Fuel/air ratio 0.074 Coolant temperature F 212 Inlet air temperature F 150 Oil temperature F 17 5 During the one minute periods with no load, the engine ran at 1600 R. P. M.

The tests were conducted for 100 hours with the octane requirement of the engine being measured after 23, 46, 69, and 92 hours. The octane requirements were determined by measuring the knocking tendency of primary reference fuels under the following engine conditions:

4 Speed R. P. M 1740 Spark advance B. T. C 15 Load B. H. P 2.5 Fuel/air ratio 0.077 Coolant temperature F 212 Inlet air temperature F Oil temperature F At the end of the tests, the combustion chamber deposits were collected and weighed.

The equilibrium octane requirement was established by plotting the observed octane requirements of the engine against time and estimating, from the slope of this curve, the magnitude of the octane requirement when the engine had reached equilibrium. The original octane re quirernent for this engine was about 73 O. N.

The test fuel was a gasoline containing 70 percent catalytic reformed stock and 30 percent straight run stock to which was added 3.0 ml. of tetraethyl lead per gallon, 1.0 theory of chlorine (based on the lead) as ethylene dichloride and 0.5 theory of bromine as ethylene dibromide.

The test crankcase lubricant was an SAE-30 weight Mid-Continent solvent-extracted distilled base oil.

Example 1 Using 0.1 percent of BrClFCCFzBr in the test fuel, under the conditions of Test Procedure I, the equilibrium octane requirement in duplicate runs was 82 O. N. and the combustion deposits 7.0 and 6.5 g. In control tests, the octane requirement was 85 O. N. and the deposit weight was 10 g.

Inspection of the engine at the completion of the test showed that the induction system of the engine was free of deposits. Both the intake and exhaust valves were clean and there was no evidence of valve burning.

Example 2 Using 0.1 percent of ClzFCCFClz in the test fuel under the conditions of Test Procedure I, the equilibrium octane requirement was 79 O. N. and the combustion deposit 4.2 g. as compared with 82 O. N. and 5.7 g. for the control.

As in Example 1, the induction system and valves were clean, with no evidence of valve burning.

Example 3 Using 0.1 percent of BrClzCCFa in the fuel under the conditions of the preceding examples, the equilibrium octane requirement was 82 O. N. and the combustion chamber deposit weight was 9.4 grams. In control tests, the equilibrium octane requirement .was 85 O. N. and the deposit weight was8.5 grams.

Example 4 A test was run under the same conditions as described in Example 1, with the exception that 2 percent by weight of BIClFCCFzBI was added to the crankcase lubricant and none was added to the test fuel. The capacity of the crankcase of the Lauson engine is two pounds of oil. The equilibrium octane requirement in this test was 82 O. N.

Example 5 For comparison, Example 1 was repeated, using 0.1 percent of the following bromo and chloro fluorohydrocarbons in the test fuel. The equilibrium octane requirements and combustion deposits do not differ significantly from the control.

Equilib- Compound rium Oc- Deposit tane Rewt., grams quirement None 85 10 F0110 O 01F: 85 10. OOlaF 85 11.3 FnBrOCBrF 85 8. 8 BIH2COBIF7- 85 10. 0 HzOBrCl 84 9. 9

TEST PROCEDURE II Another form of test was conducted in a 1951 Oldsmobile Super 88 automotive engine mounted on a test stand and coupled to a dynamometer. This engine had a compression ratio of 7.5 to 1 and a displacement of 303.7 cubic inches. The engine was operated under cyclic conditions involving three minutes of part load operation followed by one minute of operation under no load.

Three minutes of part load with the following engine conditions:

Speed Q. R. P. M 1750 Load B. H. P 20 Spark advance B. T. C 30 Oil temperature F 140 Coolant outlet temperature F 160 Coolant inlet temperature F 145 One minute of no load operation at a speed of 500 R. P. M. and a spark advance of 2.5 B. T. C.

The test was conducted for 200 hours with the octane requirement of the engine being measured at three-hour intervals. The octane requirement was determined by measuring the knocking tendency of primary reference fuels under wide-open throttle acceleration.

The equilibrium octane requirement was established by plotting the observed octane requirements of the engine against time and estimating, from the slope of this curve, the magnitude of the octane requirement when the engine had reached equilibrium. The original octane requirement of this engine was about 80.

The same test fuel and test lubricant were used as in Procedure I.

A control test using the test fuel and crankcase lubricant gave an equilibrium octane requirement of 95 O. N.

Example ,6

A test was run according to the above Test Procedure II, employing 0.1 percent by weight of BrClFCCFzBr in the test fuel. The'equilibrium octane requirement in this test was 90 O. N.

Example 7 Speed R. P. M 2000 Load B. H. P 10 Spark advance B. T. C 30 Coolant outlet temperature F 160 Coolant inlet temperature F 150 Oil temperature F 160 One minute of no load operation at a speed of 500 R. P. M. and spark set at top dead center.

The test was conducted for 200 hours with the octane requirement of the engine being determined at a speed of 1500 R. P. M. with a spark advance of 7 B. T. C. at wideopen throttle. The octane requirement of the engine was determined by measuring the knocking tendency of primary reference fuels using an external vibration pickup to detect knock.

The equilibrium octane requirement was established by plotting the observed octane'requirement of the engine against time and estimating from the slope of this curve the magnitude of the octane requirement when the engine had reached equilibrium.

The test fuel was a gasoline consisting of percent by volume of'catalytic cracked stock and 10 percent by volume-of alkylate stock to which was added 3.0 ml./gal. tetraethyl lead, 1.0 theory of chlorine (based upon lead) as ethylene dichloride and 0.5 theory of bromine as ethylene dibromide.

The crankcase lubricant was an SAE-20 weight Mid- Continent solvent-extracted distilled base oil.

A control test, using the test fuel and the test lubricant, gave an equilibrium octane requirement of 90 O. N. Th clean engine requirement was 72 O. N.

A similar test was run, employing 0.1 percent by weight of BrClFCCFzBr in the test fuel. quirement in this test was 86 O. N., or four numbers less than when the engine was operated on fuel which did not contain the BrClFCCFzBr.

Example 8 A 1951 Oldsmobile Super 88 automotive engine, modified to operate at a compression ratio of 8.75:1, was coupled to a dynamometer and operated under low-duty cyclic conditions for a period of 200 hours. This period of operation is approximately equivalent to 4000 miles of highway driving in a 1951 Oldsmobile Super 88 passenger car. The fuel for this test consisted of a mixture of 90 volume percent catalytic cracked stock and 10 percent alkylate stock to which was added 3.0 ml./ gal. of tetraethyl lead, 1.0 theory of chlorine (based on the lead) as ethylene dichloride and 0.5 theory of bromine as ethylene dibromide. The crankcase lubricant was an SAE-20 weight Mid-Continent solvent-extracted distilled base lubricating oil.

The engine operation was controlled by an electric cycle timer which permitted the engine to be operated for 30 seconds at 500 R. P. M., no load, and 2% degrees before top dead center spark ignition timing and then for 30 seconds at 1500 R. P. M., 15 brake horsepower, and 30 degrees before top dead center spark ignition timing.

At the start of the engine test and at three-hour intervals thereafter, the octane quality (number) of the fuel required for the elimination of knock and all other noises caused by abnormal combustion was determined while the engine was acceleratedunder conditions simulating a highway acceleration from 20 to 50 M. P. H. using the fourth gear of the Oldsmobile Hydramatic transmission. The quality of the fuel, required for the suppression of noise at the start of the test when the combustion chambers of the engine were essentially clean and free of deposits, was 82 Arrny-Navy performance number (an expanded octane rating scale). After 200 hours of operation, the quality of the fuel, required for the suppression of noise, had increased to 104 performance number.

In a similar test using the same fuel containing 0.1

percent by weight BrClFCCFzBr, the fuel requirement of the clean engine was again 82 performance number. After 200 hours of operation, the'quality of fuel, required for the suppression of noise, had increased to 98 performance number, or six performance numbers less than that observed when the engine was operated on fuel which did not contain the BrClFCCFzBr.

The preceding examples show definitely that the halogenated fluorine-containing ethanes of the present invention, in actual engine operation, lead to a much lower The equilibrium re-' equilibrium octane demand and usually also reduce the amountof the combustion chamber deposits and hence make possible the satisfactory operation of Otto cycle engines for long periods with fuels of lower octane rating than formerly required; and that quite similar compounds are substantially inefiective to produce such results.

It is not known how the specific substituted hydrocarbons affect the formation of deposits and the increase in octane demand nor what molecular structure is responsible for these effects.

In evaluating new gasoline additives, it. is important to determine whether or not they have a harmful effect upon such gasoline properties as stability and octane number. The following tests show that the compounds used in the present invention do not lower the quality of gasoline in these respects:

TABLE I.EFFECT OF ChFOCClzF ON OCTANE NUMBER OF GASOLINE Motor Method Research Method Weight Percent ClzFCC-ClzF-.. 0.1 0.2 O 0.1 0.2

Gasoline A 80 80 80 90.5 90.5 i 90.5 Gasoline A+3 Int/gal. Tetraethyl Lead 86.5 86.5 86.5 97.2 97.2 97.4 Gasoline A+3 mL/gal. Tetraet-hyl Lead, 1 Theory 01 as Ethylene Diohlorlde and 0.5 Theory Br as Ethylene ibrornide 86.4 86.5 86.4 97.6 97.7 97.6

The tests of Table I were made with a gasoline consisting of 90 percent catalytic cracked stock and percent alkylate stock. The octane number of this fuel was measured by the motor method (ASTM Designation D357-49) and by the research method (ASTM Designation D908-51).

BrClFCCFzBr gave like results in similar tests with several commercial gasolines.

TABLE II.-EFFECT OF ChFCCClzF ON STABILITY OF OOBIMEROIAL GASOLINES In the tests of Table II, the induction period was determined in accordance with ASTM Designation D525-49 and the formation of gum by ASTM Designation D381-50. Like tests on the effect of BrClFCCFzBr on the stability of gasolines gave similar results.

It will be understood. that the preceding; examples and tests are given for illustrative purposes solely and that this invention is not intended to be limited. to the specific embodiments disclosed therein. On the other hand, it

will be understood that the modes of introducing the halogenated fluorine-containing ethanes into the combust ion chambers of Otto cycle engines, the proportions so introduced, the proportions in the fuels and in the crankcase oils, and the composition of the fuels and of the crankcase oils, may all be varied as indicated in the generic disclosure without departing from the spirit and scope of this invention.

From the preceding description, the examples and the other tests, it will be apparent that this invention provides new and valuable modes of improving the operation of Otto cycle engines, and novel and valuable fuels and lubricants adapted to efiect such improved modes of operation, whereby such engines can be operated more economically over longer periods of time than was previously possible. Therefore, it is apparent that this invention constitutes a valuable contribution to and advance in the art.

What is claimed is:

1. A motor fuel for Otto cycle engines which comprises gasoline, tetraethyl lead, and from about 0.1% to about 2% by weight, based on the gasoline, of at least one halogenated fluorine-containing ethane of the group consisting of l-bromo-1,1-dichloro-2,2,2-trifluoroethane, l,Z-dibromo-l-chloro-1,2,2-trifiuoroethane and l,1,2,2- tetrachlorol ,2-difiuoroethane.

2. A motor fuel for Otto cycle engines which comprises gasoline, tetraethyl lead, and from about 0.1% to about 2% by weight, based on the gasoline, of 1,1,2,2- tetrachloro-1,2-dilluoroethane. I

3. A motor fuel for Otto cycle engines which comprises gasoline, tetraethyl lead, and from about 0.1% to about 2% by Weight, based on the gasoline, of 1,2-dibromo-l-chloro-1,2,2-tritluoroethane.

4. A motor fuel for Otto cycle engines which comprises gasoline, tetraethyl lead, and from about 0.1% to about 2% by weight, based on the gasoline, of l-bromo- 1,1-dich1oro-2,2,2-trifluoroethane.

5. A crankcase mineral lubricating oil for Otto cycle engines containing from about 2% to about 10% by weight of at least one halogenated fluorine-containing ethane of the group consisting of 1-bromo-l,1-dichloro- 2,2,2-trifiuoroethane, 1,2-dibromo-1-chloro-1,2,2-trifluoroethane and l,1,2,2-tetrachloro-l,2-difluoroethane.

6. A crankcase mineral lubricating oil for Otto cycle engines containing from about 2% to about 10% by weight of 1, l ,2,2-tetrachloro- 1 ,2-difluoroethane.

7. A crankcase mineral lubricating oil for Otto cycle engines containing from about 2% to about 10% by weight of 1,2-dibromo-1-chloro-1,2,2-trifluoroethane.

8. A crankcase mineral lubricating oil for Otto cycle engines containing from about 2% to about 10% by weight of l-bromo-l,1-dichloro-2,2,2-trifluoroethane.

Industrial and Engineering Chemistry, vol. 46, No. 8, pages 1677-1684, August 1954.

Claims

1. A MOTOR FUEL FOR OTTO CYCLE ENGNES WHICH COMPRISES GASOLINE, TETRAETHYL LEAD, AND FROM ABOUT 0.1% TO ABOUT 2% BY WEIGHT, BASED ON THE GASOLINE, OF AT LEAST ONE HALOGENATED FLUORINE-CONTAINING ETHANE OF THE GROUP CONSISTING OF 1-BROMO-1,1-DICHLORO-2,2,2-TRIFLUOROETHANE, 1,2-DIBROMO-1-CHLORO-1,2,2-TRIFLUOROETHANE AND 1,1,2,2TETRACHLORO-1,2-DIFLURORETHANE.

5. A CRANKCASE MINERL LUBRICATING OIL FOR OTTO CYCLE ENGINES CONTAINING FROM ABOUT 2% TO ABOUT 10% BY WEIGHT OF AT LEAST ONE HALOGENATED FLUORINE-CONTAINING ETHANE OF THE GROUP CONSISTING OF 1-BROMO-1-1-DICHLORO2,2,2-TRIFLUOROETHANE, 1,2-DIBROMO-1-CHLORO-1,2,2,TRIFLUOROETHANE AND 1,1,2,2-TETRACHLORO-1,2-DIFLUOROETHANE.