FUEL ADDITIVE TO REDUCE LOW-SPEED PRE-IGNITION IN DIRECT INJECTION GASOLINE ENGINES

Abstract

The present invention relates to a fuel additive for reducing pre-ignition phenomena (LSPI), said additive comprises an active chemical function comprising at least one diarylamine compound remarkable in that said additive further comprises a solvent used to dissolve the chemical function, said solvent comprising isoparaffin. The invention also relates to the use of a fuel additive in a fuel tank of a motor vehicle, said additive being according to the invention. The invention also relates to a motor vehicle comprising a direct injection gasoline engine, the gasoline further comprising an additive according to the invention. Figure 1

Description

Title of the invention: FUEL ADDITIVE FOR REDUCING LOW-SPEED PRE-IGNITION IN DIRECT INJECTION GASOLINE ENGINES Technical field

[0001] The present invention relates to the field of motor vehicle fuels. The invention relates in particular to fuel additives intended for direct injection gasoline engines. Prior art

[0002] Current direct injection gasoline engines suffer from an injection problem known as low speed pre-ignition, also known by the English acronym "LSPI" (Low Speed ​​Pre-Ignition).

[0003] Indeed, this is a negative phenomenon in which the ignition of the combustible mixture takes place before the ignition controlled by the spark plug (nominal combustion mode), resulting in a propagation of the pre-ignition to the rest of the combustion chamber. This phenomenon is accentuated at high load or at high average pressures and at low engine speed, triggering pressures in the combustion chamber which can exceed 200 bars. The occurrence of pre-ignition can therefore be destructive for the internal organs of gasoline engines.

[0004] It should be noted that the pre-ignition phenomenon is different from other phenomena linked to abnormal combustion, such as self-ignitions for example, commonly called knocking, the latter being knocking causing a resonance of the explosion on the walls of the combustion chamber and the piston.

[0005] However, the potential for damage from pre-ignitions is significantly higher than in the case of knocking, for example. Pre-ignition significantly limits the performance of modern engines.

[0006] Among the main causes of the pre-ignition phenomenon are the engine architecture and its driving conditions, the physicochemical properties of the lubricant used, as well as the composition and quality of the gasoline used. Indeed, poor fuel quality is considered to be one of the main causes of pre-ignition.

[0007] Poor fuel quality can be remedied by adding specific molecules to the fuel. At the same time, studies have shown that fuel composition also plays a role in the process of creating pre-ignition.

[0008] However, until now, and with the use of additives having mainly a For the purpose of cleaning the combustion chambers, only negative effects of said additives on the ignition tendency were observed.

[0009] On the other hand, it has been shown that the droplets of engine oil present in the combustion chamber play a role in the occurrence of the negative phenomenon. For this purpose, special engine oils with a lower tendency to pre-ignition have been developed in recent years.

[0010] However, the use of such oils does not effectively reduce the risk of pre-ignition. Indeed, common detergents, which are used for cleaning injectors, have an undesirable effect, as do certain types of hydrocarbons that are part of the fuel composition, such as heavy n-paraffins.

[0011] Another existing solution which could possibly allow the reduction of the pre-ignition phenomenon consists of reducing the engine performance, i.e. reducing the speed or the compression ratio, but the disadvantage of this solution is a reduction in engine efficiency leading to an increase in CO2 emissions.

[0012] Published patent document EP 3 420 054 A1 discloses a fuel additive for cleaning the combustion chambers of an internal combustion engine, the document further discloses that the use of a mixture of diarylamine in combination with an antioxidant in a fuel could reduce pre-ignition events in a partially charred combustion chamber.

[0013] However, the solution proposed by document EP 3 420 054 A1 presents a margin for improvement in order to further reduce the pre-ignition phenomenon, particularly with fuels of poor quality and in combustion chambers having combustion residues and for which cleaning is not necessarily desired. Statement of the invention

[0014] The present invention aims to overcome at least one of the drawbacks of the aforementioned state of the art. More particularly, the invention aims to propose an additive configured to be mixed with gasoline in a motor vehicle tank, said additive notably improving the quality of the fuel and being capable of limiting or even eliminating the negative phenomenon of pre-ignition in order to guarantee the longevity of the engine.

[0015] For this purpose, the invention relates to a fuel additive intended to reduce pre-ignition phenomena, said additive comprises an active chemical function comprising at least one diarylamine compound, remarkable in that said additive further comprises a solvent used to modify or dissolve the chemical function, said solvent comprising isoparaffin.

[0016] Preferably, the additive is configured to be introduced into a motor vehicle tank when filling said tank with fuel so that the latter is mixed with the additive of the invention.

[0017] According to one embodiment, the solvent is a mixture of isoparaffin having a boiling point above 40°C and Methyl tert-butyl ether (MTBE).

[0018] According to one embodiment, methyl tert-butyl ether (MTBE) corresponds to 2-methoxy-2-methylpropane.

[0019] According to one embodiment, the solvent comprises a concentration of 30% to 60% by volume relative to the total volume of the additive, and preferably, the solvent comprises a concentration of 50% to 60% by volume relative to the total volume of the additive.

[0020] According to one embodiment, the at least one diarylamine compound corresponds to at least one diphenylamine derivative comprising a mixture of a reaction product of diphenylamine and 2,4,4-trimethylpentene.

[0021] A derivative is a chemical compound originating from another compound, following transformations carried out on the latter, more particularly, a diphenylamine derivative originates preferentially from a diarylamine compound.

[0022] According to one embodiment, the at least one diphenylamine derivative comprises N-[(1,1,3,3-Tetramethy Ibuty l)phenyl 1] naphthalen-1 - amine.

[0023] According to one embodiment, the active chemical function further comprises at least one phenolic antioxidant, said phenolic antioxidant is an isomeric mixture of C7-9-Alkyl-3-(3,5-di-trans-butyl-4-hydroxyphenyl)propionate with methyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate butylhydroxytoluene.

[0024] The invention also relates to the use of a fuel additive in a fuel tank of a motor vehicle, said additive being according to the invention.

[0025] According to one embodiment, the fuel is gasoline, and the ratio of additive to gasoline used in the tank is between 1:200 and 1:300.

[0026] The invention also relates to a motor vehicle comprising a direct injection gasoline engine, the gasoline further comprising an additive according to the invention.

[0027] Advantageously, the mixing of the additive in the fuel significantly improves its quality and considerably reduces pre-ignition phenomena or even eliminates them. To this end, the longevity of the motor vehicle engine is preserved.

[0028] It is therefore possible, thanks to the invention, to be able to sell motor vehicles having modern gasoline engines in countries where the quality of the fuel is not sufficient and / or poor. Brief description of the drawings

[0029] [Fig. 1] is a graph illustrating the occurrence of the pre-ignition phenomenon of a gasoline engine with and without use of the additive of the invention. Detailed description

[0030] It has been demonstrated, by the present invention, that the use of a fuel additive comprising an active chemical function and a solvent comprising isoparaffin used to dissolve the chemical function, makes it possible to reduce pre-ignition phenomena in the combustion chambers of direct injection gasoline engines.

[0031] In the present description, the phenomenon of pre-inflammations will be designated by LSPI.

[0032] Several experimental tests were carried out with a series of different chemical formulations in order to develop the additive of the invention. Indeed, it was demonstrated that the ignition temperature of a mixture, i.e. mixture of oil with fuel and additive, had a correlation with the frequency of LSPI during the tests carried out, given that LSPI is linked to the ignition of the fuel.

[0033] However, it has been noted that the correlation between the frequency of LSPI and the ignition temperature of the fuel is not always present, in particular at a normal operating pressure in a combustion chamber of a gasoline engine, i.e. between 8 and 12 bars, since the evaporation processes of the mixture play an important role in the results under these conditions.

[0034] In this regard, the ignition temperature of the mixture was measured under pressure using the DSC method, i.e. the English acronym for “Differential Scanning Calorimetry”, at a pressure of 10 bars.

[0035] Under the measurement conditions of the DSC method, evaporation of the mixture does not affect the results as much as at normal pressures and a stronger correlation between the ignition temperatures of the mixture and the frequency of LSPIs was noticed.

[0036] In the experimental tests carried out, a combination of more than one di-phenylamine derivative with a combination of several phenolic antioxidants having a significant difference in boiling points, further decreased the ignition temperature of the pressurized fuel.

[0037] More specifically, the additive developed following the various tests, comprises an active chemical function comprising at least one diarylamine compound corresponding to several diphenylamine derivatives, the latter comprising N-[(1,1,3,3-Tetramethylbutyl)phenyl]naphthalen-1-amine as well as a mixture of a reaction product of diphenylamine and 2,4,4-trimethylpentene.

[0038] Preferably, the additive comprises between 20 and 50% by volume of diphenylamine derivatives relative to the total volume of said additive.

[0039] The additive of the invention also comprises a solvent for dissolving the chemical function, and having a concentration of between 30% and 60% by volume in the additive.

[0040] The solvent corresponds to a mixture of isoparaffin having a boiling point above 40°C, with 2-methoxy-2-methylpropane.

[0041] The additive further comprises several phenolic antioxidants, the latter preferably being an isomeric mixture of C7-9-Alkyl-3-(3,5-di-trans-butyl-4-hydroxyphenyl)propionate with methyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate butylhydroxytoluene.

[0042] Preferably, the volume concentration of antioxidants in the additive is about 10%, the term about meaning ±20% of the nominal value.

[0043] [Fig. 1] is a graph illustrating the occurrence of LSPI of a gasoline engine with and without use of the additive of the invention.

[0044] Indeed, the graph in [Fig.l] results from an experimental test carried out with the chemical formulation of the additive of the invention and with concentrations of 55 vol% in solvent, 35 vol% of diphenylamine derivatives and 10 vol% of antioxidants.

[0045] The experimental test was carried out on a 4-cylinder, side-mounted direct injection gasoline engine, and in order to simulate real-life usage conditions, the additive of the invention was mixed with a good quality engine oil and another oil considered to be of poor quality.

[0046] The mixing ratio of the additive to the gasoline is preferably between 1:200 and 1:300, and even more preferably 1:250, i.e. use of one liter of additive for 250 liters of gasoline for example.

[0047] In parallel, the combustion of the mixture was observed using a poor quality gasoline fuel and with the additive of the invention, as well as with said fuel, but without the additive.

[0048] With reference to [Fig.l], the combustion chambers of the engine experienced several pressures P, and the LSPI took place only using the fuel not including the additive, in particular at pressures ranging from 110 to 150 bars.

[0049] Indeed, the occurrence N of the LSPI of [Fig.l] concerns only the poor quality fuel which has not been mixed with the additive of the invention.

[0050] In the same test, no LSPI occurred using a mixture of poor quality fuel with good or poor quality oil and the additive of the invention, regardless of the combustion chamber pressure.

[0051] In this configuration, the additive significantly improves poor fuel quality and eliminates pre-ignition phenomena (LSPI).

[0052] Advantageously, mixing the additive of the invention with a poor quality fuel makes it possible to preserve the overall mechanical health and longevity of the modern gasoline engines of motor vehicles.

Claims

Claims

1. Additive for reducing pre-ignition phenomena in automotive gasoline fuel with direct injection engine, said additive comprises an active chemical function comprising at least one dia-rylamine compound characterized in that said additive further comprises a solvent used to dissolve the chemical function, said solvent comprising isoparaffin.

2. Additive according to claim 1, characterized in that the solvent is a mixture of isoparaffin having a boiling point above 40°C and Methyl tert-butyl ether (MTBE).

3. Additive according to claim 2, characterized in that the methyl tert-butyl ether (MTBE) corresponds to 2-methoxy-2-methylpropane.

4. Additive according to one of claims 1 to 3, characterized in that the solvent comprises a concentration of 30% to 60% by volume relative to the total volume of the additive.

5. Additive according to one of claims 1 to 4, characterized in that the at least one diarylamine compound corresponds to at least one diphenylamine derivative comprising a mixture of a reaction product of diphenylamine and 2,4,4-trimethylpentene.

6. Additive according to one of claims 1 to 5, characterized in that the at least one diphenylamine derivative comprises N- [(1,1,3,3 -Tetramethyl Ibuty Ijpheny 1] naphthalen-1 - amine.

7. Additive according to one of claims 1 to 6, characterized in that the active chemical function further comprises at least one phenolic antioxidant, said phenolic antioxidant is an isomeric mixture of C7-9-Alkyl-3-(3,5-di-trans-butyl-4-hydroxyphenyl)propionate with methyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate butylhy-droxytoluene.

8. Use of a fuel additive in a fuel tank of a motor vehicle, said additive being according to one of claims 1 to n

9. / . Use according to claim 8, characterized in that the fuel is gasoline, and the ratio of the additive to the gasoline used in the tank is between 1:200 and 1:

300.

10. A motor vehicle comprising a direct injection gasoline engine, the gasoline further comprising an additive according to one of claims 1 to 7.

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