US2725857A - Method of and composition for reducing the octane requirement of an engine - Google Patents

Description

United States Patent O ce M25357 r Patented Dec. 6, 1955 in ASTM Bulletin, No. 154, October 1948, page 53 Betz725857 ter lead scavenging needed for aviation gasoline, by E.

METHOD OF AND COMPOSITION FOR REDUCING THE OCTANE REQUIREMENT OF AN ENGINE Cleveland, Ohio, a corporation of Ohio N Drawing. Application March 19, 1954, Serial No. 417,516

Claims. (Cl. 123-1) The present invention relates to a method of and composition for reducing the tendency of an internal combustion engine to knock.

It is ell known that deposits quickly accumulate in the combustion chambers of internal combustion engines such as those used in automobiles. An engine containing deposits is said to have a higher octane requirement than a clean engine because it requires a gasoline with a higher octane rating if the engine is not to knock. This becomes apparent to the driver of an automobile having a dirty engine by the tendency of the engine to knock while accelerating, climbing a hill or otherwise operating the engine under greater than normal load. The deleterious effects of such accumulations of deposits are particularly noticeable in engines having a high compression ratio because the margin between the octane numbers of gasolines on the market and the octane requirement of the engine when clean is narrower than for engines having lower compression ratios. When such an engine becomes dirty the octane number of the gasoline required by the engine in order not to knock is increased and often reaches a value higher than the octane rating of gasolines generally available.

When the fuel used in an internal combustion engine contains tetraethyl lead, an agent which in effect raises the octane rating of the fuel, the increase in octane requirement of the engine with continued use becomes greater than when non-leaded fuels are used, especially under mild conditions simulating ordinary driving. Thu-s, whereas the octane requirement of an internal combustion engine operating on non-leaded fuel under the conditions of. a standard engine test described hereinafter may increase from say 70 for a clean engine to 78 for a dirty engine and then level oil? at that figure, the octane requirement in the same engine, if run on leaded fuel, will increase to 82 or more for a dirty engine before levelling oit.

It has been found that the deposits in the combustion chambers in internal combustion engines run on leaded fuel are different on different surfaces, apparently because of their diiferent average temperatures. In an aviation engine, for example, the metal temperatures of the piston, cylinder intake valve and exhaust valve are 300 to 500, 400 to 600, 600 to 800 and 1000 to 1200 F., respectively. The composition of the deposits appears to depend on the metal temperature of the particular surface. Where the metal temperature is of the order of about 400 F. the deposits analyze about 50 to 60% lead and consist of from about 25 to 30% lead sulfite and lead sulfate, 20% lead monoxide, 35 to 40% lead bromide and about carbon. Where the metal temperature is considerably higher, i. e., of the order of 1000 to 1200" E, the lead content is about 70% and the deposits are composed almost entirely of lead sulfate, lead sulfite and lead monoxide, the concentration of lead bromide being extremely small and the amount of carbon being practically zero. These observations are recorded A. Droegemueller. 7

It is well known, of course, that ordinarily the octane requirement of an engine, whether it be an automobile, marine or airplane engine, is reduced in order to restore or at least to approach its original efficiency by the process of removing a cylinder head and grinding or abrading off the deposits found on the various surfaces of the combustion chamber, such as the piston top, the cylinder wall, cylinder head and the intake and exhaust valves.

This method, while quite elfective, has the disadvantage of requiring skilled labor and a considerable amount of time to dismantle, clean and reassemble the engine. It is therefore responsible, when carried out on engines of commercial vehicles, for making it necessary to withdraw the vehicle completely from service while the engine is being overhauled. g Y

A great number of other methods have been proposed heretofore for cleaning the combustion chambers of an engine without removing the cylinder head. One of these methods is that of introducing a liquid solvent into the carburetor while the'engine is running. Although this method produces great billows of smoke at the exhaust,

it has been found, upon taking apart an engine so treated, that little of the deposits are actually removed.

In accordance with this invention, the octane requirement of a dirty internal combustion engine, which term is intended to include spark ignition and fuel injection type engines, is reduced by coating the deposit-bearing surfaces of the combustion'charnbers of a dirty engine with a composition containing silverborate, copper borate or a combination thereof and then running the engine. The coating of the combustion chamber wall surfaces may be accomplished in any desirable manner, such'as by spraying or squirting the composition into the combustion chamber through an opening such as that provided by removal of the spark plug or injection nozzle. The composition to be applied to the dirty combustion chamber walls essentially comprises two components. One component is chemically .reactive with lead or its compounds under the conditions within the combustion chambers of a running internal combustion engine and comprises silver borate, copper borate or a combination thereof. The other essential component performs the purely physical function of adhering the reactive component to the combustion chamber walls and is a thick, tacky, metal-adhering material or mixture of materials that is fairly viscous or non-flowable at ambient temperatures, non-corrosive to the engine parts, and preferably readily removable from the combustion chamber by eventual volatilization and/or combustion under the conditions in the combustion chamber.

In addition to the desirable reduction in octane requirement effected by the composition and method of the invention, there is obtained, most surprisingly, a suppression of octane requirement increase in engine operations following the application of the composition to the combustion chamber surfaces. This additional effect is most advantageous because the coating operation not only reduces the octane requirement, but at the same time prolongs the effect thereof.

The copperborate may readily be prepared by reaction of borax with copper sulfate or copper nitrate. The silver borate may be prepared in similar fashion, e. g., by reaction of borax with silver nitrate.

Because of the purely physical function of the vehicle or carrier component, its chemical composition and structure are not particularly critical so long as it is capable of carrying the borate, adhering to metal and combustion chamber deposits, and does not damage the engine. Generally, viscous and tacky hydrocarbons that are capable of being volatilized. or consumed under the conditions of combustion in the combustion chamber of a running engine and thereby removed,, are preferred as vehicles in the composition. Such vehicles or carriers include petroleum bright stocks,polybutenes,.petrolatums, hydro.- carbon oils thickenedrif v desired-,,to; gel fornrwith suitable thickening agents such as hydrogenated castor oil, andgreases, particularly the softer greases. One group of vehicles that has been found particularly useful comprises various mixtures of petroleum bright stock andv viscous synthetic polybutene, in which the bright stock has a viscosity of about 700 to 23.00 S. S. U. at-100I" F. and the polybutene has a molecular weight of about 700-to 1250.

Itv is, of. course, desirable that; the composition contains the highest possible concentration, of. borate consistent. with. the requirements; that the composition, be fairly viscous and capable of adhering to the combustionchanlber walls; andv particularly tothe: deposits: on the walls. Withthese considerations in view,,the compositionofthe invention should contain at:least about by weight of borateto be elfective, and at least suthcient vehicle, i. e., a minimum of about 10% by weight, to effect the physical function of adhering the composition to the combustion chamber walls.

The amount of borate introduced into each combustion chamber depends, as will readily be understood, upon the weight and type of, deposits in the combustion chamber, the dimensions of the combustion chamber, and the extent to which they are to be removed or rendered inactive in exerting an unfavorable catalytic effect on the combustion of the fuel in the engine. The amount of borate introduced into each combustion chamber in accordance with this embodiment of the invention should therefore be an. appreciable. amount, i. e., sufiicient to effect the desired reduction: in octane requirement. For engines which have reached an equilibrium octane requirement, i-. e., a requirement that will not increase substantially with continued; operation,.it has been found that amounts as low as aboutone gram of the borate per combustion chamber are effective, amounts in the range of between about 5 and grams per combustion chamber being preferred. Amounts above about 25 grams per combustion chamber maybe utilized. so longas they are. insufiicient to interfere with the operation of the engine, but are undesirable since they merely add to the expense but not to the effectiveness of the treatment. Generally, therefore, it is desirableto introduce between about 1 and 25,, preferably between about 5 and- 15 grams of the borate into each combustion chamber. The amount of the, composition employed in, each, combustion chamber is governed by. the foregoingamounts as well as by-the general considerations that a. coatingthereof should not have a thickness exceeding about /s".

While it is to be understood thatthe scope'of, the invention is not to be limited by any theory advanced herein,

it is believed that the lead in, the lead sulfate, lead sulfite and lead oxides forming the combustion chamber deposits in engines running on leaded motor fuels is, by reason of its variable valence, in anactive'state and: probably exerts an unfavorable catalytic effect on the cornbustion of the fuel in the engine. It is believed that by treating these lead salts with silver or copper borate, a.

binary compound is formed in the, deposits which the lead is comparatively inactive, since it can no longer,

move freely from one valence state to another, and, itscatalytic action is thereby inhibited.

The advantages and utility of the. invention: willbecome more apparent. from. the following example included herein for illustrative purposes only:

Example Copper borate was prepared by; adding 1 cc. concentrated nitric acid to 30grams (0.125 mol') copper nitrate, Cu(NO3)z.3H'2O, in a few cc. of water and adding the resultingsolution to a solution of 48 grams' (0.125 mol) borax, Na2B4O'1.1OH2O, in 250 cc. water heated to 140 F. washed several times with water and once with methanol, and then dried by spreading. Analysis of the precipitate showed it to contain 8.0% boron.

60 grams of the copper borate thus obtained were ground for four hours in a mechanical grinder and mixed to a fairly smooth paste, referred to in this example as Paste A, with. 30 grams of Pennsylvania bright stock having a viscosity of1590 S. S. U. at F. and 30 grams of a viscous, synthetic polybutene, available commercially as oronite. polybutene No. 24, having a molecular weight of about 840.

Silver borate was prepared by adding a solution, heated to F., of 435 grams (1.5 mole) sodium tetraborate, NazBsOmSHzO (USP refined powder.) dissolved in 2100 grams of water, to a solution, likewise heated to 140' R, of 510 grams (3 mols) silver nitrate, AgNOs, dissolved'in 430 grams-ofwater. A white precipitateformed immediately, was filtered, washed six times with water and twice with methanol, and spread out to dry. It was further dried by use of an infra-red lamp. The solid precipitate was found, upon analysis, to contain 7.3% boron.

50 grams of the silver borate thus obtained were ground for four hours. in a mechanical grinder and mixed to a smooth paste, referred to in this example as. Paste B, with 55 grams of the same Pennsylvania bright stock and 25 grams oronite polybutene No. 24."

A standard, clean, six-cylinder Chevrolet automobile engine was run on gasoline containing 3 cc. per gallon tetraethyl, lead under a standard procedure designed to approximate ordinary driving conditions and dirty the engine. This procedure, involves running the engine for five minutes at 2000 R. P. M., corresponding to a road speed of 40 M. P. H. with standard. spark advance, an oil temperature of 190 F, and a water temperature at the jacket outlet of F., and then running the engine for one minute at 500 R. P. M. under idling conditions. This six minute cycle was repeated until the octane requirement of the engine had arrived at an equilibrium value. In measuring the octane requirement at intervals of, about eight hours,v the engine was operated under the following conditions:

Spark advance l1- BTDC Air fuel ratio 13.5

After the octane requirement had risen from an initial. value of' 71 to an equilibrium value of 81, the spark plugs were removed and Composition. A, consisting of a mixture of 60 grams copper borate, 30 grams of petroleum bright stock, and 30 grams of polybutene No. 24, was coated on the combustion chamber walls of the dirty engine to a thickness of about ,4,".

After the spark plugs were replaced, the engine testing procedure previously described was resumed and the octane requirement of the engine was measured after 1 and 26 hours of operation alternately at 2000 and 500 R. P. M; It was found that the octane requirement of the engine was 82 after the first hour, and 74 after 26 hours.

The entire procedure was repeated with Composition 1?- consisting of a mixture of 50 grams silver borate, 55 grams petroleum bright stock and 25 grams polybutene No. 24. It was found that two hours after coating the combustion chamber walls of the dirty engine to the thickness of about Lg" with Composition B, the octane requirement had been lowered from the equilibrium requirement of 81 to a value of 77.

These tests show that both compositions etfected significant reductions in octane requirements, thus indicat A blue precipitate formed immediately, was filtered ing effectiveness in inhibiting undesirable catalytic action on the part of the engine deposits.

It is to be expected that variations and modifications of this invention will readily occur to those skilled in the art upon reading the present description. All such modifications are intended to be included within the scope of the invention as defined in the accompanying claims.

We claim:

1. A method of reducing the octane requirement of a dirty internal combustion engine having lead-containing deposits on the surfaces forming the combustion chambers which comprises coating the deposit-bearing combustion chamber surfaces with a composition essentially comprising from about to 90% by weight of a viscous, metal-adhering vehicle that is non-corrosive to the engine parts and contains from about 90 to 10% of an inorganic boron compound selected from the group consisting of silver borate and copper borate, and then running the engine.

2. The method defined in claim 1 in which the composition is coated on the combustion chamber surfaces by introducing it through the spark plug openings of the engine and the vehicle component of the composition is a hydrocarbon.

3. The method defined in claim 1 in which the vehicle component of the composition is a mixture of a petroleum bright stock having a viscosity of about 700 to 2300 SSU at 100 F. and a viscous synthetic polybutene having a molecular weight of about 700 to 1250.

4. A method of reducing the octane requirement of a dirty internal combustion engine having lead-containing deposits on the surfaces forming the combustion chambers which comprises coating the deposit-bearing combustion chamber surfaces with a composition essentially comprising from about 50 parts by Weight of silver borate, 55 parts by weight of a petroleum bright stock having a viscosity of about 1590 SSU at 100 F., and 25 parts by weight of a polybutene having a molecular weight of about 840, and then running the engine.

5. A method of reducing the octane requirement of a dirty internal combustion engine having lead-containing deposits on the surfaces forming the combustion chambers which comprises coating the deposit-bearing combustion chamber surfaces with a composition essentially comprising from about 60 parts by weight of copper borate, 30 parts by weight of a petroleum bright stock having a viscosity of about 1590 SSU at 100 F., and 30 parts by weight of a polybutene having a molecular weight of about 840, and than running the engine.

6. A composition for reducing the octane requirement of a dirty internal combustion engine which comprises from about 10 to 90% by weight of a viscous, metaladhering essentially organic vehicle that is non-corrosive to the engine parts and contains from about 90 to 10% of an inorganic boron compound selected from the group consisting of silver borate and copper borate.

7. A composition for reducing the octane requirement of a dirty internal combustion engine which comprises from about 10 to 90% by weight of silver borate and from about 90 to 10% by weight of a viscous, metaladhering, non-corrosive mixture of a petroleum bright stock having a viscosity of about 700 to 2300 SSU at 100 F. and a polybutene having a molecular weight of about 700 to 1250.

8. A composition for reducing the octane requirement of a dirty internal combustion engine which comprises from about 10 to 90% by weight of copper borate and from about 90 to 10% by weight of a viscous, metaladhering, non-corrosive mixture of a petroleum bright stock having a viscosity of about 700 to 2300 SSU at 100 F. and a polybutene having a molecular weight of about 700 to 1250 9. A composition for reducing the octane requirement of a dirty internal combustion engine which comprises from about parts by weight of silver borate, parts by weight of a petroleum bright stock having a viscosity of about 1590 SSU at 100 F., and 25 parts by Weight of a polybutene having a molecular weight of about 840.

10. A composition for reducing the octane requirement of a dirty internal combustion engine which comprises from about parts by weight of copper borate, 30 parts by Weight of a petroleum bright stock having a viscosity of about 1590 SSU at F., and 30 parts by Weight of a polybutene having a molecular Weight of about 840.

References Cited in the file of this patent UNITED STATES PATENTS 1,848,831 Kodama Mar. 8, 1932 2,151,432 Lyons et a1 Mar. 21, 1939 2,552,555 Houdry May 15, 1951

Claims (1)

1. A METHOD OF REDUCING THE OCTANE REQUIREMENT OF A DIRTY INTERNAL COMBUSTION ENGINE HAVING LEAD-CONTAINING DEPOSITS ON THE SURFACES FORMING THE COMBUSTION CHAMBERS WHICH COMPRISES COATING THE DEPOSIT-BEARING COMBUSTION CHAMBER SURFACES WITH A COMPOSITION ESSENTIALLY COMPRISING FROM ABOUT 10 TO 90% BY WEIGHT OF A VISXOUS, METAL-ADHERING VEHICLE THAT IS NON-CORROSIVE TO THE ENGINE PARTS AND CONTAINS FROM ABOUT 90 TO 10% OF AN INORGANIC BORON COMPOUND SELECTED FROM THE GROUP CONSISTING OF SILVER BORATE AND COPPER BORATE, AND THEN RUNNING THE ENGINE.