RU2283437C2 - Method to reduce separation of deposits in combustion chamber and method to decrease exhaust when starting internal combustion engine from cold - Google Patents

Abstract

FIELD: mechanical engineering; internal combustion engines.

SUBSTANCE: proposed method to reduce separation of deposits in combustion chamber of internal combustion engines with spark ignition in which deposits are formed in combustion chamber includes delivery of fuel with addition containing metal compound into internal combustion engine with spark ignition. Said metal containing compound is delivered in amount sufficient for effective reduction of separation of deposits in combustion chamber. Method to decrease exhaust when starting internal combustion engine with spark ignition from cold includes reduction of separation of deposits in combustion chamber of internal combustion engine with spark ignition. Metal containing compound is delivered in amount sufficient for effective decrease of exhaust when starting engine from cold.

EFFECT: reduced separation of deposits in combustion chamber and exhausts when starting engine from cold.

28 cl, 1 ex, 1 tbl

Description

The present invention relates to a method for reducing the peeling of deposits in the combustion chamber and, accordingly, reducing emissions during cold start. The method includes burning fuel having a fuel additive containing a metal compound. In one example, the metal compound is a manganese-containing compound.

BACKGROUND OF THE INVENTION

During the operation of internal combustion engines with spark ignition (carbureted, with fuel injection into the inlet channels of KVT, with multipoint distributed injection of MTV, with direct injection of PVB gasoline, etc.), deposits accumulate in the combustion chamber ( ACS). This deposition is the result of both inefficient combustion of fuel during the working stroke, and thermal polymerization reactions of certain fuel components, resulting in a material with a high molecular weight, which does not burn very well. Deposits are formed both on the surfaces of the cylinder head inside the combustion chamber, and on the upper plane of the pistons. In particular, deposition on the upper plane of the piston is sensitive to fuel and moisture and tends to curl and fall off when the deposition is wetted by fuel and / or wetted. Symptoms of this exfoliation occur during a cold start, when a charge of the fuel mixture blows off deposits from the combustion chamber into the seats of the exhaust valves. Thus, the flakes of deposits stuck in this new place clog the working surfaces of the exhaust valves and prevent the strong sealing necessary to localize the charge of the air-fuel mixture during the compression stroke, which prevents its ignition and leads to the need for additional cranking of the crankshaft in order to removing deposits so that the engine can start normally. With this scrolling, the charge of the fuel mixture, instead of being in the cylinder for subsequent spark ignition, is prematurely ejected into the exhaust system and loads the catalytic exhaust gas afterburner with uncleaned fuel. Part of this crude fuel leaves the exhaust pipe of the exhaust gas aftertreatment system and may contribute to HC emissions during cold start. In addition, when the engine finally starts, subsequent hot gaseous products of combustion ignite this untreated fuel. Intensive burning of untreated fuel in the exhaust system can lead to the melting of the catalytic exhaust gas afterburner due to the extremely high temperatures developed during this combustion and serious damage to the exhaust pipe of the exhaust gas aftertreatment system.

Symptoms of ACS peeling were considered in connection with the introduction of improved emission control strategies aimed at reducing hydrocarbon emissions during cold start. The reason for all these changes is the discovery that a significant part of all hydrocarbon emissions from automobiles is generated within the first 90 seconds when using traditional, underfloor, three-pass catalytic exhaust afterburners for ignition during a cold start. Therefore, the reduction of this time interval is of particular importance. State environmental authorities also take this fact into account and require that car manufacturers develop an on-board diagnostic system (OBD) in order to monitor the operation of the emission control system in order to minimize hydrocarbon emissions into the environment and to ensure that this system fulfills its task within specific warranty period.

Changes in the regulation of emissions have led to difficulties in cold starting attributed to increased fuel consumption, which leads to peeling of deposits in the combustion chamber, which are stuck in the area of the working surface of the exhaust valve, thereby preventing good sealing during compression and leading to misfire. The BDS system immediately detects this due to subsequent increased emissions of hydrocarbons due to unburned fuel and turns on a malfunction indicator light (SIN) on the dashboard, which indicates the need to come to the representative office of the manufacturer to eliminate the defects. Difficulties during cold start due to peeling of the ACS tend to occur mainly in engines with a large displacement and a large number of cylinders (in 6-, 8- and 10-cylinder engines), because in these large engines the crankshaft cranking speed is lower, and it takes longer to blow off exfoliated deposits from the exhaust valves.

One way to solve the cold start problem due to peeling of the ACS is to exclude trips over short distances with low load, which leave the camera to withstand for long periods of time. Another way to get around this problem is to simply continue to crank the crankshaft to blow out deposits that interfere with the normal operation of the flakes and, after starting up, make the engine run at high speeds for an additional thirty seconds to clean out any remaining flaking deposits. However, this method inevitably leads to very high levels of hydrocarbon emissions, as a result of which the BIN SIN may turn on.

Description of the invention

It was found that the delamination of deposits in the combustion chamber (ACS) can be reduced and even eliminated using an additive to a fuel containing a metal compound. In one example, the manganese-containing compound, MMT, completely suppresses peeling of the ACS.

A method of reducing peeling of combustion chamber deposits in spark ignition internal combustion engines in which combustion chamber deposits are present comprises the steps of supplying a fuel containing an additive that contains a metal-containing compound to a spark-ignition internal combustion engine, wherein the metal-containing compound is supplied in an amount sufficient to effectively reduce flaking of deposits in the combustion chamber.

The metal-containing compound may be a compound containing one or more of the following metals: manganese, platinum, palladium, rhodium, iron, cerium, copper, nickel, silver, cobalt and molybdenum, and mixtures thereof. An example of a manganese compound is described in more detail here, but other metal-containing additives can be used. In each alternative, the metal compound in the fuel is burned in a spark ignition internal combustion engine. The use of a metal-containing additive reduces or eliminates peeling of the ACS.

Fuels and additives, in this case, are suitable for burning in any internal combustion engine with spark ignition. Specific engines that will benefit include engines having carburetor systems, inlet fuel injection systems, multipoint distributed injection systems, and direct gasoline injection systems. In addition, options for the aforementioned turbocharged and supercharged engines will benefit. Other engines that have improved emission controls, including, for example, exhaust gas recirculation, will also benefit. In addition, Otto or two-stroke internal combustion engines will benefit.

The basics of unleaded gasoline in today's fuel composition are traditional motor fuel distillates boiling over a total range of about 70 ° F to 440 ° F. They include essentially all grades of unleaded gasoline currently used in spark ignition internal combustion engines. In general, they contain both direct race fractions and cracked feeds, with alkylated hydrocarbons, converted hydrocarbons, and the like. or without them. Such gasolines can be prepared from saturated hydrocarbons, for example, direct race intermediates, alkylation products, etc., with detergents, antioxidants, dispersants, metal deactivators, rust inhibitors, multifunctional additives, demulsifiers, plasticizing oils, deicers, combustion catalysts, corrosion inhibitors, emulsifiers, surfactants, solvents, or other similar and known additives. It is envisaged that under certain conditions, these additives may be included in concentrations in excess of normal levels.

In general, base gasoline is a mixture of intermediates derived from several refining processes. The final mixture may also contain hydrocarbons obtained in other procedures, for example, alkylates obtained by reaction of C ₄ olefins and butanes using an acid catalyst, for example sulfuric acid or hydrofluoric acid, and aromatic compounds obtained from a reforming unit.

The motor gasoline basics used to create the fuel mixtures of the invention typically have initial boiling points in the range of about 70 ° F to 100 ° F, and final boiling points in the range of about 420 ° F to 440 ° F, which are measured using a standard ASTM distillation procedures (ASTM D-86). Intermediate gasoline fractions boil off at temperatures within these limits.

It is also advisable to use base gasolines having a low sulfur content, since sulfur oxides tend to contribute to the irritating and asphyxiating characteristics of smog or other forms of atmospheric pollution. To the extent that it is economically feasible, base gasolines contain no more than about 100 ppm sulfur in the form of traditional sulfur-containing contaminants. Another alternative includes fuels in which the sulfur content does not exceed about 30 ppm.

The gasoline bases used in this invention should be lead free or practically lead free. However, gasoline may contain antiknock amounts of other agents, for example, cyclopentadienyl-nickel-nitrosyl, N-methyl-aniline, and the like. Antiknock promoters, such as 2.4 pentanedione, may also be included. In some cases, it is desirable that the gasoline contain additional additives to protect against regressive wear of the valve and valve seat. Non-limiting examples include boron oxides, bismuth oxides, ceramic bonded CaF ₂ , iron phosphate, tricresyl phosphate, phosphorus and sodium based additives, and the like. The fuel may further contain antioxidants, for example, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, phenylenediamines, for example, N-N'-di-sec-butyl-p-phenylenediamine , N-isopropylphenylenediamine and the like. Similarly, gasoline may contain dyes, metal deactivators, or other additives that serve some useful purposes. The following are descriptive characteristics of one common gasoline base. Obviously, in the fuel mixture of the Applicant, many other standard and specialized gasolines can be used.

GASOLINE CHARACTERISTICS

API Density (@ 60 ° F)
Reid vapor pressure, EPA (psi)
Sulfur (parts per million)
Research Octane
Engine octane
R + M / 2
Oxidizing agents (%)
Aromatic compounds (%)
Olefins (%)
Paraffins (%) 50-70
6-8
0-500
85-120
75-90
87-110
0-30
0-50
0-30
30-100

ASTM Distillation
Evaporation vol.% Temp., F. NTK 70-100 5 100-130 10 120-140 fifteen 140-160 twenty 150-170 thirty 170-190 40 190-210 fifty 200-220 60 220-240 70 240-260 80 280-300 90 340-370 95 380-400 CT 420-440

One metal that can be used includes atomic or ionized manganese, its precursors, and mixtures of metal compounds, including manganese. These manganese compounds can be organic or inorganic. Also effective is the generation, isolation or production of manganese or manganese ions in place.

Inorganic metal compounds in this example may include, by way of example, but not limitation, fluorides, chlorides, bromides, iodides, oxides, nitrates, sulfates, phosphates, nitrides, hydrides, hydroxides, carbonates, and mixtures thereof. Metal sulfates and phosphates can be effective and may not represent unacceptable additional by-products of the combustion of sulfur and phosphorus in certain fuels and combustion applications. Organometallic compounds in this example include alcohols, aldehydes, ketones, esters, anhydrides, sulfonates, phosphonates, chelates, phenates, crown ethers, carboxylic acids, amides, acetylacetonates mixtures thereof.

Illustrative manganese-containing organometallic compounds are manganese-tricarbonyl compounds. Such compounds are mentioned, for example, in US patent No. 4568357; 4,674,447; 5,113,803; 5,599,357; 5944858 and in European patent No. 466512 B1.

Suitable manganese-tricarbonyl compounds that can be used include cyclopentadienyl-manganese-tricarbonyl, methylcyclopentadienyl-manganese-tricarbonyl, dimethylcyclopentadienyl-manganese-tricarbonyl, trimethylcyclopentadienyl-manganese-tricarbonyl-tetramethylcyclopentadienyl-manganese-tetramethylcyclopentadienyl-manganese-tetramethylcyclopentadienyl-manganese-tetramethylcyclopentadienyl-manganese-tetramethylcyclopentadienyl-manganese-tetramethylcyclopentadienyl-manganese-tetramethylcyclopentadienyl-manganese-tetramethylcyclopentadienyl-manganese-tetramethylcyclopentadienyl-manganese-tetramethyl cyclopentadienyl-manganese-tetramethyl cyclopentadienyl-manganese-tetramethyl cyclopentadienyl-manganese-tetramethyl tricarbonyl, diethylcyclopentadienyl-manganese-tricarbonyl, propylcyclopentadienyl-manganese-tricarbonyl, isopropylcyclopentadienyl-manganese- rikarbonil, tert-butylcyclopentadienyl manganese tricarbonyl, oktiltsiklopentadienil manganese tricarbonyl, dodetsiltsiklopentadienil manganese tricarbonyl, etilmetiltsiklopentadienil manganese tricarbonyl, indenyl manganese tricarbonyl, and like, including mixtures of two or more such compounds. One alternative involves cyclopentadienyl-manganese-tricarbonyls which are liquid at room temperature, for example methylcyclopentadienyl-manganese-tricarbonyl, ethyl cyclopentadienyl-manganese-tricarbonyl, liquid mixtures of cyclopentadienyl-manganese-tricarbonyl, and methylcyclopentadienyl-manganese-tricarbonyl-tricarbonylbenzene and ethylcyclopentadienyl-manganese-tricarbonyl, etc.

The preparation of such compounds is described in the literature, for example, in US patent No. 2818417, the contents of which are incorporated into the description by reference in its entirety.

In the preparation of additives to be used according to the methods of the invention, the metal-containing compound should be used in quantities sufficient to reduce or completely eliminate the peeling of the ACS in the spark ignition internal combustion engine. Amounts may vary depending on the particular metal or mixture of metals and metal-containing compounds. In an example of a manganese-containing compound, the amount of added manganese may be from about 1 to about 50 mg of manganese per liter.

It is believed that metal-containing compounds act as a free radical scavenger and a combustion catalyst. As a radical scavenger, compounds can suppress fuel-induced polymerisation reactions initiated by radicals and, thus, limit the contribution to hydrocarbon ACS. As a combustion catalyst, manganese, for example, is catalytically involved in the mechanism of ACS removal due to enhanced carbon oxidation at low temperatures.

The term “cold start emissions” should be understood within the industrial definition. The industrial definition of cold start emissions is specified in FTP-75 (State Test Procedure). This procedure is described in detail in the US Code of Federal Regulations (CFR 40, part 86). Briefly, the test procedure consists of the following three phases: 1) cold start, 2) intermediate state, and 3) hot start. The FTP-75 emission cycle simulates a distance of 11.04 miles (17.77 km) over 1874 seconds at an average speed of 21.2 miles per hour (34.1 km / h). Before testing, the engine is kept overnight at 25 +/- 5 ° C to guarantee cold starting conditions. After a cold start, an intermediate phase follows. Then the engine is shut off for holding at elevated temperature for 10 minutes, and then start up again for the hot phase. Emissions in each phase are collected in a separate Teflon tank for each phase of the test and analyzed. The amount of each emission component (HC, CO, CO ₂ , NO _x , etc.) is expressed in g / mile (g / km) for each phase. For hydrocarbon emissions (HC), the cold start phase is most important because it provides 80-90% of all emissions in the three phases.

Examples

When testing the engine, fuels were included, including and not including a metal-containing compound. The manganese additive in MMT® was used at a concentration of 8.25 mg of manganese per liter of fuel.

A six-cylinder Dodge Intrepid was used in this study. He traveled 3,000 miles on a CITGO RUL gasoline test cycle without additives. At the end of the test, the engine was disassembled and evaluated for peeling of the ACS according to the procedure published by Gautam T. Kalghatgi in SAE Series 2002-01-2833.

Test Procedure: ACS Peeling Test at Dodge Intrepid

Ethics Test Plan

Car
Fuel
Test No. 1
Test number 2
Cycle Chrysler dodge intrepid
CITGO normal unleaded
without MMT
with MMT additive
IVD Chassis Dyno cycle (average speed 45 mph)
Two shifts per day (about 600 miles)
Exposure overnight
End of test after 3,000 miles

At the end of the test:

1. Disassemble the engine, as after a normal IVD / ACS test

2. Measure the thickness of the deposits on the head and pistons using a template

3. Sprinkle the top surface of the pistons with soapy water (1 drop of liquid household detergent per 100 ml of water) using a sprayer for home plants

4. After 3 hours, photograph the piston bottoms and note the degree of exfoliation

5. Spray the upper surface of the pistons again and leave overnight.

6. Take a picture of the upper surface of the pistons and note the degree of exfoliation

7. Remove exfoliated deposits using vacuum and weigh.

8. Take a picture of the top surface of the pistons

9. Measure the thickness of the remaining deposits using a template

10. Scrape and calculate the total weight of deposits on the upper surface of the piston

11. Complete the determination of IVD and ACS on the head.

The term "average" means the amount of deposits averaged over six valves or six upper surfaces of the pistons or six places on the cylinder head corresponding to six pistons.

Table 1:
Suppression of peeling of ACS with a manganese-containing additive Additive The number of exfoliated ACS (milligrams) Total engine ACS (milligrams) IVD engine (milligrams) No 89.4 783.4 312.2 there is 0 688.9 305.9

As can be seen from this test example, the use of a specific metal-containing additive leads to the complete elimination of delamination of the combustion chamber deposits. In other words, when using the additive, peeling of the ACS does not occur. You can use other metal-containing additives and vary the concentration of any additive. By changing the set of additives and / or the concentration of the additive, it is possible to control the reduction of peeling. It is assumed that, in the case of a manganese-containing additive, a concentration of about two mg of manganese per liter of fuel can provide a reduction of approximately 50% of the peeling of ACS.

In view of the detection of the absence of peeling of the ACS, it is obvious that more complete combustion occurs, especially during the cold start of the engine. There are no flakes blocking the sealing of the exhaust valves. Due to this, less crude fuel can pass through the cylinder and enter the exhaust system. Accordingly, hydrocarbon emissions during cold start are reduced by the use of an additive in spark ignition internal combustion engines, in which there are deposits in the combustion chamber.

It should also be understood that the reagents and components referred to by their chemical names anywhere in the text of the description of the invention or the claims, whether in the singular or plural, are identified as existing before coming into contact with another substance referred to by its chemical name or chemical type ( e.g. base fuel, solvent, etc.). It does not matter what chemical changes, transformations and / or reactions, if any, occur in the resulting mixture or solution or reaction medium, since such changes, transformations and / or reactions are the natural result of putting said reagents and / or components together in conditions specified in accordance with this description. Thus, the reagents and components are identified as ingredients that must be placed together either during the desired chemical reaction (for example, the formation of an organometallic compound) or during the formation of the desired composition (for example, an additive concentrate or an additive fuel mixture). It is also obvious that the additive components can be added or mixed to the base fuels individually by themselves and / or as components used in the formation of pre-prepared combinations and / or additives. Accordingly, although in the following claims, substances, components and / or ingredients may be referred to in the present tense (“contains”, “is”, etc.), we are talking about substances, components and / or ingredients existing at a time as times before they are first mixed with one or more other substances, components and / or ingredients in accordance with the present description. Thus, the fact that substances, components or ingredients may lose their original identity due to a chemical reaction or transformation during such mixing operations or immediately after them is completely unimportant for an accurate understanding and appreciation of the description and claims.

In many places throughout this specification, references are made to US patents, published foreign patent applications, and published technical documents. All of these documents are specifically incorporated in their entirety into this description, as if they were fully set forth here.

This invention is subject to known changes with respect to practical application. Therefore, the foregoing description is not intended to limit and should not be construed as limiting the invention to the specific embodiments presented above. On the contrary, everything that is subject to coverage is set forth in the following claims and their equivalents having legal force.

The patent owner did not intend to publicly disclose any disclosed embodiments, and, to the extent that any disclosed modifications or changes may literally not correspond to the scope of the claims, they should be considered as part of the invention according to the doctrine of equivalence.

Abbreviations and symbols used in this description, in addition to those already decrypted in the text of the description, have the following meanings:

API - American Petroleum Institute, American Petroleum Institute (referring to measurements taken on the recommendations of this institution);

R + M / 2 - half the sum of the research (Research) and motor (Motor) octane numbers;

NTK - initial boiling point;

CT is the final boiling point;

IVD - Intake Valve Deposits, deposits on intake valves.

Claims (28)

1. The method of reducing the peeling of deposits in the combustion chamber in internal combustion engines with spark ignition, in which there is deposits in the combustion chamber, comprising the step of: supplying fuel containing an additive that includes a metal-containing compound to an internal combustion engine with spark ignition, where the metal-containing compound served in an amount sufficient to effectively reduce the exfoliation of deposits in the combustion chamber. 2. The method according to claim 1, characterized in that the metal-containing compound contains one or more of the following metals: manganese, platinum, palladium, rhodium, iron, cerium, copper, nickel, silver, cobalt and molybdenum, as well as mixtures thereof. 3. The method according to claim 2, characterized in that the metal-containing compound is a manganese-containing compound. 4. The method according to claim 3, characterized in that the manganese-containing compound is an inorganic compound of manganese. 5. The method according to claim 4, characterized in that the inorganic compound of manganese is selected from the group consisting of fluorides, chlorides, bromides, iodides, oxides, nitrates, sulfates, phosphates, nitrides, hydrides, hydroxides, carbonates and mixtures thereof. 6. The method according to claim 3, characterized in that the manganese-containing compound is an organometallic compound. 7. The method according to claim 6, characterized in that the organometallic compound is selected from the group consisting of alcohols, aldehydes, ketones, esters, anhydrides, sulfonates, phosphonates, chelates, phenates, crown ethers, carboxylic acids, amides, acetyl- acetonates and mixtures thereof. 8. The method according to claim 3, characterized in that the manganese-containing compound contains from 1 to 50 mg of manganese per liter of fuel. 9. The method according to claim 6, characterized in that the organometallic compound contains methylcyclopentadienyl-manganese-tricarbonyl. 10. The method according to claim 3, characterized in that the manganese-containing compound is selected from the group consisting of cyclopentadienyl-manganese-tricarbonyl, methylcyclopentadienyl-manganese-tricarbonyl, dimethylcyclopentadienyl-manganese-tricarbonyl, trimethylcyclopentadienyl-manganese-tricarbonyl, tetramethylene pentamethylcyclopentadienyl-manganese-tricarbonyl, ethylcyclopentadienyl-manganese-tricarbonyl, diethylcyclopentadienyl-manganese-tricarbonyl, propylcyclopentadienyl-manganese-tricarbonyl, isopropyl iclopentadienyl-manganese-tricarbonyl, tert-butylcyclopentadienyl-manganese-tricarbonyl, octylcyclopentadienyl-manganese-tricarbonyl, dodecylcyclopentadienyl-manganese-tricarbonyl, ethylmethylcyclopentadienyl-manganese-tricarbonyl, indenyl-manganese-more such mixtures of two-manganese. 11. The method according to claim 1, characterized in that the fuel contains sulfur in an amount of less than 30 parts per million. 12. The method according to claim 1, characterized in that the internal combustion engine with spark ignition comprises a fuel injection system selected from the group consisting of a fuel injection system into the intake channels, a multipoint distributed injection system and a direct gasoline injection system. 13. The method according to claim 1, characterized in that the fuel is a normal unleaded gasoline. 14. The method according to claim 1, characterized in that the engine includes six or more cylinders. 15. A method of reducing emissions during cold start of internal combustion engines with spark ignition, including reducing peeling of deposits in the combustion chamber of internal combustion engines with spark ignition, characterized in that said reduction of peeling of deposits in the combustion chamber includes the step of: supplying fuel containing an additive that includes a metal-containing compound in a spark ignition internal combustion engine, where the metal-containing compound is supplied in an amount sufficient to efficiently effective reduction of emissions during cold start. 16. The method according to clause 15, wherein the metal-containing compound contains one or more of the following metals: manganese, platinum, palladium, rhodium, iron, cerium, copper, nickel, silver, cobalt and molybdenum, as well as mixtures thereof. 17. The method according to clause 16, wherein the metal-containing compound is a manganese-containing compound. 18. The method according to 17, characterized in that the manganese-containing compound is an inorganic compound of manganese. 19. The method according to p. 18, characterized in that the inorganic compound of manganese is selected from the group consisting of fluorides, chlorides, bromides, iodides, oxides, nitrates, sulfates, phosphates, nitrides, hydrides, hydroxides, carbonates and mixtures thereof. 20. The method according to 17, characterized in that the manganese-containing compound is an organometallic compound. 21. The method according to claim 20, wherein the organometallic compound is selected from the group consisting of alcohols, aldehydes, ketones, esters, anhydrides, sulfonates, phosphonates, chelates, phenates, crown ethers, carboxylic acids, amides, acetyl- acetonates and mixtures thereof. 22. The method according to 17, characterized in that the manganese-containing compound contains from 1 to 50 mg of manganese per liter of fuel. 23. The method according to claim 20, characterized in that the organometallic compound contains methylcyclopentadienyl-manganese-tricarbonyl. 24. The method according to 17, characterized in that the manganese-containing compound is selected from the group consisting of cyclopentadienyl-manganese-tricarbonyl, methylcyclopentadienyl-manganese-tricarbonyl, dimethylcyclopentadienyl-manganese-tricarbonyl, trimethylcyclopentadienyl-manganese-tricarbonyl, tetramethyl pentamethylcyclopentadienyl-manganese-tricarbonyl, ethylcyclopentadienyl-manganese-tricarbonyl, diethylcyclopentadienyl-manganese-tricarbonyl, propylcyclopentadienyl-manganese-tricarbonyl, isopropyl iklopentadienil manganese tricarbonyl, tert-butylcyclopentadienyl manganese tricarbonyl, oktiltsiklopentadienil manganese tricarbonyl, dodetsiltsiklopentadienil manganese tricarbonyl, etilmetiltsiklopentadienil manganese tricarbonyl, indenyl manganese tricarbonyl, including mixtures of two or more such compounds. 25. The method according to clause 15, wherein the fuel contains sulfur in an amount of less than 30 parts per million. 26. The method according to clause 15, wherein the spark ignition internal combustion engine comprises a fuel injection system selected from the group consisting of a carburetor system, a fuel injection system into the intake channels, a multipoint distributed injection system and a direct gasoline injection system. 27. The method according to clause 15, wherein the fuel is a normal unleaded gasoline. 28. The method according to clause 15, wherein the engine includes six or more cylinders.