EP0639632B1 - Use of an additive for lead-free, spark-ignited internal combustion engine fuels for reducing valve seat recession. - Google Patents

Abstract

A novel anti-wear additive to unleaded internal combustion engine fuels (petrols) contains at least one alkali metal salt or alkaline earth metal salt of an alkyl sulphosuccinate in combination with a detergent and, if appropriate, with other fuel additives known per se.

Description

The invention relates to the use of an additive for unleaded Gasoline fuels to prevent or reduce Valve seat wear, which is essentially at least one Alkali metal or alkaline earth metal salt of an organic Sulfonic acid and at least one ashless detergent as well optionally contains other known additives.

With the introduction and spread of the unleaded Gasoline is the problem that vehicles with leaded gasoline could be operated without complaint, suddenly showed dramatic valve seat wear on the exhaust valve if unleaded petrol has been used.

As a remedy for this, the Addition of additives to the fuels used proposed been.

These wear protection additives protect the exhaust valve seats of gasoline engines and enable use unleaded petrol also for the operation of end-of-life vehicles, not yet in terms of using unleaded petrol are specially equipped.

As additives to protect against valve seat wear In particular, additives containing alkali metals have been proposed.

For example, U.S. Patent 3,955,938 describes (Exxon) Compositions based on inorganic and organic sodium salts that work together with ashless Dispersants as additives in unleaded fuels to protect the valve seats.

EP 0 288 296 (BP Chemicals) uses as an additive a fine-particle metal salt dispersion against valve seat wear, especially a dispersion of potassium borate, Sodium borate, potassium carbonate and potassium bicarbonate.

According to EP 0 301 448 (BASF), the fuels contain to prevent or reduce wear and tear on the valves and for simultaneous reduction of corrosion phenomena alkali metal or alkaline earth metal salts of monoamides of dicarboxylic acids with 2 up to 4 carbon atoms between the carboxyl groups or of amides of tri- or tetracarboxylic acids, the amino nitrogen at least one hydrocarbon group, optionally is oxygen or amine substituted. These additives are said to work simultaneously through their detergent action also keep the motors clean.

EP-A1-0 307 815 (BASF) relates to fuels, in which small amounts of copolymers of olefins and / or cycloolefins with maleic anhydride and / or copolymers of alkyl vinyl ethers and / or cycloalkyl vinyl ethers with maleic anhydride and / or copolymers of alkyl vinyl ethers and / or cycloalkyl vinyl ethers and olefins and / or contain cycloolefins with maleic anhydride are, the carboxyl groups entirely or partially under Formation of alkali metal or alkaline earth metal salts and the Rest of the carboxyl groups with alcohols and / or amines corresponding ester and / or amide groups and / or ammonium groups are implemented.

EP 0 342 497 (BASF) also describes Purpose of preventing wear and tear on the wearer Valves and the simultaneous reduction of corrosion the addition of copolymers Alkyl (meth) acrylates and / or vinyl esters from optionally monoethylenically unsaturated carboxylic acids, the All or part of the carboxyl groups of the copolymers Alkali are implemented to form the alkali metal salts and the rest of the acid groups with ammonia and / or amines to the corresponding amide groups and / or ammonium salts is implemented.

In EP-A1-0 207 560 (Shell) alkali metal and alkaline earth metal salts of hydrocarbon-substituted Succinic acid as wear protection additives described. The hydrocarbon substituents on the or have the alpha carbon atom (s) of this succinic acid a length of 20 to 200 carbon atoms.

The hydrocarbon-substituted succinic acid derivatives are the subject of an extensive older and newer patent literature. Also the imide derivatives of these substances are used alone or in because of their dispersing action Combination with other additives used.

In EP-A-233 250 (Lubrizol) is used as an additive against the valve seat wear a combination of alkaline or compositions containing alkaline earth metals and ashless dispersants proposed. Of those containing alkali metals Concretely, only the compositions Salts of organic alkyl aryl sulfonic acids; both Dispersants are those already mentioned, known alkenyl succinimides, which are usually at least contain about 30 aliphatic carbon atoms.

The PCT application WO 91/07477 (Rechem) deals deal with the improvement of the ignition behavior of fuels and as an addition to this discloses alkali metal and alkaline earth metal salts of mono- or diesters of Sulfosuccinic acid. These compounds are succinic acid derivatives are in which the carboxylic acid group (s) with Hydrocarbon residues are esterified and an alpha carbon atom of succinic acid through a sulfonic acid group is substituted. These sulfosuccinic acid esters are in Form of alkali metal or alkaline earth metal salts.

This group of connections is in the professional world not new. It has been suggested earlier, as have they like other surfactants than antistatic Additives (FR-PS 1 602 314 Mobil Oil), as a preventive agent the formation of soot in the exhaust gases of diesel engines (GB 1 066 878 SHELL) or as a means of improving combustion behavior or for the purification of exhaust gases in Use internal combustion engines in general (AT-PS 337 333 Mohnhaupt).

The aim of the present invention was now to Inexpensive wear protection additive for unleaded petrol to provide the valve seat wear on the engine output side Completely prevented and at the same time for keeping the engine clean worries. In addition, the entire range of tests commonly used today according to the state of the art for fuel components.

Surprisingly, it has been shown that the in another connection known salts of sulfosuccinic acid esters fulfill this purpose particularly well. This could not to be foreseen as at the time of the older publications the problem of valve seat wear unleaded gasoline was not known and the PCT application WO / 07477 deals with a different task increasing spark plug performance and increasing the flame speed occupied.

in welcher R¹ und R² unabhängig voneinander für Wasserstoff oder eine aliphatische Kohlenwasserstoffgruppe stehen, mit der Maßgabe, daß höchstens einer der Reste R¹ bzw. R² Wasserstoff bedeutet, M für ein Alkalimetall- oder Erdalkalimetallion steht und n der Wertigkeit von M entspricht, in Kombination mit einem aschefreien Detergenz als Verschleißschutzadditiv verwendet zur Herabsetzung bzw. Verhinderung von Ventilsitzverschließ.According to the invention, a neutral alkali metal and / or alkaline earth metal salt of a mono- or diester of sulfosuccinic acid of the general formula I is thus used

in which R ¹ and R ² independently of one another are hydrogen or an aliphatic hydrocarbon group, with the proviso that at most one of the radicals R ¹ or R ^{2 is} hydrogen, M is an alkali metal or alkaline earth metal ion and n corresponds to the valence of M. , used in combination with an ash-free detergent as a wear protection additive to reduce or prevent valve seat closures.

The aliphatic groups can be saturated or be unsaturated groups, optionally also substituents can wear. Examples of suitable substituents are: Hydroxy, ether, ketone, phenyl or ester groups in Question that's the same on the two hydrocarbon groups or can be different.

Mono- or diesters of sulfosuccinic acid can be used, it being possible for the carboxyl group in the α-position to the SO ₃ group, the β-position carboxyl group or both carboxyl groups to be esterified with the same or different radicals. The salts of the diesters of sulfosuccinic acid are preferred. They have proven to be soluble in gasoline to an extent which allows the desired amount of the alkali metal or alkaline earth metal additive to be adjusted without difficulty. The chain length of the aliphatic hydrocarbon group in the ester radical is preferably 4 to 20 carbon atoms. Hydrocarbon radicals with a chain length of 6 to 13 carbon atoms, in particular with a chain length of about 8 carbon atoms, are particularly preferred.

Mixtures of the salts mentioned can also be used will.

The alkali metal salts of the sulfosuccinic acid esters are preferred, being for the purpose of protecting the Exhaust valves the potassium salts proved to be particularly cheap to have.

Apart from the excellent wear protection effect was still in the additives used according to the invention found another surprising effect, namely a demulsifying effect in the presence of water. As is well known is a complete freedom of the gasoline from water difficult to reach. Due to condensation effects almost always expected the presence of moisture will. The new additives with their demulsifying Effect reduce the adverse effects of such Water contamination. The fuel stays clear that Phase interfaces are sharp and there are none Solids.

The salts of the sulfosuccinic acid esters also work as a surfactant, what the formulation of additive packages for high demands on engine cleanliness. However, since the problem of engine pollution and the formation of disturbing deposits on the intake valves is still very important in modern engines, it is necessary for the additives used according to the invention, they together to formulate with detergents. They are all different ash-free detergents, such as long-chain amide-imide compounds, long chain amines, polyethers or polyether amines suitable. The polybutenamines have been particularly advantageous in combination with the salts of sulfosuccinic acid esters proven. The detergents preferably have one average molecular weight from 2000 to 3000.

As mentioned, the additives used according to the invention can also contain other known additives. Frequently e.g. Corrosion protection is desirable or necessary.

Another part of all modern additive packages are the so-called "carrier oils". These either exist from mineral oil fractions or they are synthetic products, such as. Poly alpha olefins. Usually it's the detergents which are formulated as a solution in a carrier oil and therefore bring this component into the additive package. In addition, the alkali metal component can also be added a carrier oil to be easier to handle.

If necessary, the entire additive package for easier processing, solubility in petrol and lower viscosity at low temperatures with a diluent, possibly also aromatic components may contain. Aromatic are preferred Kerosene can be used for this purpose. With help Such diluents can have viscosity limits of about 800 cP at -20 ° C are observed for European Ratios are favorable.

The proportions of alkali metal component for detergents are preferably in the range of 1: (8-15), these details refer to detergents, which if necessary contain a carrier oil.

Depending on the requirements, additive 15 % By mass to 40% by mass, preferably 30% by mass to 40 % By mass, of an aromatic kerosene as a diluent contain.

Process for the preparation of the metal salts of Mono- or diesters of sulfosuccinic acid are already known and are described in GB 446 568, 760 121 or 1,050,578.

A fuel for gasoline engines, the one according to the invention contains used additive, corresponds to the put to it Requirements if it is 0.01 milligram atom (mVal) to 2.5 milligram atom (mVal) of alkali metal per kg of fuel contains. The preferred range is between 0.02 mVal and 1.0 mVal, in particular between 0.07 mVal and 0.25 mVal Alkali metal per kg of fuel.

For the preferred potassium, this means that a potassium content of 0.5 mg - 100 mg per kg of fuel is used becomes. The ranges 1 mg to 30 mg are preferred, in particular 3 mg to 10 mg of potassium per kg of fuel.

The invention will now be illustrated by the following examples explained in more detail.

Additive :

It becomes a wear protection additive from the following Components created:

The alkali metal component consists of a Potassium sulfosuccinic acid dioctyl ester. If this component is present without carrier oil, it contains about 8.5% by mass Potassium.

The detergent is based on Polybutenamine.

A portion comes from the detergent component Carrier oil, including the potassium sulfosuccinate with carrier oil can be formulated.

The product contains an aromatic for dilution Kerosene.

6,3 Masse-% K-Sulfosuccinat-Komponente

70,4 Masse-% Detergens-Komponente

23,3 Masse-% Kerosen

Der Kaliumgehalt dieses Additivs liegt bei 0,31 Masse-%. The mixing ratios in this specific example are as follows:

6.3 mass% K-sulfosuccinate component

70.4 mass% detergent component

23.3% by mass of kerosene

The potassium content of this additive is 0.31% by mass.

This additive is added in an amount of 1100 ml 1000 liters of fuel added, so that per kg of fuel about 4 mg of potassium are included.

Application example

To the positive influence of the manufactured according to the invention Fuel on the wear of not specially hardened Show exhaust valves in gasoline engines on Engine test bench carried out a comparison test over 50 h. A test engine of a type often represented on the market Gray cast iron cylinder head without specially hardened exhaust valve seats is operated for 50 hours at high load and high speed, being unleaded, commercial fuel once without and once with the additive according to the invention in the above amount is used.

After completing the tests, the exhaust valve seats face the one that is operated with unleaded fuel Motors sink in as a result of regular Valve clearance adjustment several times that of the manufacturer prescribed valve clearance. When operating with unleaded Fuel that the additive according to the invention in of the dosage mentioned can only be a minor one Depression that is a fraction of the prescribed Valve clearance is measured.

Example of use 2

To show that unleaded fuel with the additive according to the invention also in long-term operation, the effectiveness of a modern exhaust gas cleaning system for gasoline engines (Lambda probe; 3-way catalytic converter) not negatively influenced, was a vehicle endurance test with vehicles of the same type performed over 80,000 km. Here was a vehicle with commercially available, unleaded petrol without and one with the additive according to the invention in that tested in application example 1 Dosing in controlled road operation. The effectiveness of the emission control system and the comparability for emissions of both vehicles was at the start of the test according to the Austrian regulations for Exhaust gas typing checked.

After the end of the driving test, better emissions are measured with the vehicle which was operated with unleaded petrol plus the additive according to the invention in the stated dosage than with the vehicle which had been driven without the additive. The exhaust gas limit values for CO ₂ , HC and NO _x specified in the typing regulations are significantly undercut.

Example of use 3

Deposits in the intake tract and on the intake valves modern gasoline engines with according to the legal Requirements of fine-tuned mixture preparation and emission control systems can reduce running behavior and exhaust emissions significantly affect.

In a Europe-wide standardized test run (CEC F-05-T-92) with a 4-cylinder gasoline engine the deposit behavior of non-additive and additive Petrol rated comparable.

In this test, the additive according to the invention brings about the following improvements with regard to the formation of deposits on the inlet valves: Test fuel: Deposits: Gasoline (Eurosuper) without additives 350 to 700 mg / valve Gasoline (Eurosuper) + addition less than 100 mg / valve (1 g / 1000 g petrol)

Claims (13)

1. Use, as an additive for unleaded petrols to prevent or reduce valve seat wear, of a neutral alkali metal and/or alkaline-earth metal salt of a mono- or diester of sulphosuccinic acid of the general formula (I)

   

   wherein R¹ and R², independently of each other, represent hydrogen or an aliphatic hydrocarbon group, on condition that at most one of the residues R¹ or R² signifies hydrogen, M represents an alkali metal or alkaline-earth metal ion and n corresponds to the valency of M, combined with at least one ash-free detergent and optionally other known additives.
2. Use, for the purpose mentioned in claim 1, of a salt of a sulphosuccinic acid diester of the formula I mentioned in claim 1 combined with an ash-free detergent.
3. Use, for the purpose mentioned in claim 1, of a salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1, in which the ester groups consist of hydrocarbon residues with from 4 to 20 carbon atoms, combined with an ash-free detergent.
4. Use, for the purpose mentioned in claim 1, of a salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1, in which the ester groups consist of hydrocarbon residues with from 6 to 13 carbon atoms, combined with an ash-free detergent.
5. Use, for the purpose mentioned in claim 1, of a salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1, in which the ester groups consist of hydrocarbon residues with 8 carbon atoms, combined with an ash-free detergent.
6. Use, for the purpose mentioned in claim 1, of an alkali metal salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1 combined with an ash-free detergent.
7. Use, for the purpose mentioned in claim 1, of a potassium salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1 combined with an ash-free detergent.
8. Use, for the purpose mentioned in claim 1, of an alkali metal and/or alkaline-earth metal salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1 combined with a detergent based on polybutene amine.
9. Use, for the purpose mentioned in claim 1, of an alkali metal and/or alkaline-earth metal salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1 combined with a detergent based on polyether amine.
10. Use, for the purpose mentioned in claim 1, of an alkali metal and/or alkaline-earth metal salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1 combined with an ash-free detergent with a molecular weight of from 2000 to 3000.
11. Use, for the purpose mentioned in claim 1, of a potassium salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1 combined with an ash-free detergent in a weight ratio of 1:(8-15).
12. Use, for the purpose mentioned in claim 1, of a mixture of from 4 wt.% to 9 wt.% alkali metal salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1 and from 60 wt.% to 80 wt.% ash-free detergent, the weight being made up to 100 % with carrier oil and/or diluent.
13. Use, for the purpose mentioned in claim 1, of a mixture containing a potassium salt of a sulphosuccinic acid ester of the formula I mentioned in claim 1 and an ash-free detergent, potassium being present in an amount of from 0.2 wt.% to 0.7 wt.%.