WO2010136822A2

WO2010136822A2 - Method and use

Info

Publication number: WO2010136822A2
Application number: PCT/GB2010/050922
Authority: WO
Inventors: Anthony Cooney; Trevor Russell; Vincent Burgess; Simon Mulqueen
Original assignee: Innospec Limited
Priority date: 2009-05-29
Filing date: 2010-06-01
Publication date: 2010-12-02
Also published as: GB0909380D0; WO2010136822A3

Abstract

A method of controlling deposits and/or improving the efficiency and/or improving the fuel economy in a direct injection spark ignition gasoline engine comprises adding into the gasoline to be combusted: (i) a detergent compound which is the reaction product of a carboxylic acid-derived acylating agent and an amine; and (ii) optionally, one or more additional components selected from: a) carrier oils comprising an optionally esterified polyether; b) polyetheramines; c) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms; d) nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine; e) aromatic esters of a polyalkylphenoxyalkanol.

Description

METHOD AND USE

This invention relates to a method of controlling deposits, improving efficiency and in particular improving fuel economy in a direct injection spark ignition gasoline engine, and the use of detergent-containing additive compositions for this purpose.

With over a hundred years of development the spark ignition (Sl) engine has become a highly tuned piece of engineering. As the SI engine has become more highly tuned it has become more sensitive to variations in its construction. The construction of such engines can change with use as deposits build up on certain components and through wear of other components. These changes in construction may not only change parameters such as power output and overall efficiency; they can also significantly alter the pollutant emissions produced. To try and minimise these time- related changes to an engine's construction fuel additives have been developed to minimise wear and deposit build-up phenomena. Examples include anti valve seat recession additives to reduce wear and detergents to reduce deposit build-up.

As engine technology has evolved so have the demands put upon fuel additive packages. Early gasoline detergents were formulated to overcome the problem of deposit build-up on carburettors. In a carburettor a partial vacuum in part of the engine intake system is used to draw fuel into the induction system. To provide better control of the fuel air mixture carburettors were replaced with fuel injection equipment where a pressure above atmospheric pressure was used to force the fuel into the intake system and to induce better atomisation of the fuel.

As a replacement for carburettors so called throttle body injectors were used with just a single injector taking the place of the carburettor. The position of a throttle body injector was thus very similar to that of the carburettor and the temperature regime was thus similar.

To obtain greater control over the fuel delivery into the engine cylinders there was a move to using individual fuel injectors for each cylinder. These injectors were thus placed in the individual inlet ports for each cylinder; this configuration thus became known as port fuel injection or PFI. Because the fuel injector was now placed closer to the combustion chamber it tended to get hotter, also as it was closer to the engine inlet port it was more likely to be subjected to exhaust gases passing back into the inlet system during the initial part of the inlet valve opening event. This made the injector more prone to deposit build up and thus increased the demands on the fuel additive required to minimise this deposit build-up.

All these systems so far outlined were designed to provide an air fuel mixture that was approximately stoichiometric. The engine power was determined by the amount of stoichiometric mixture provided to the cylinder. This was controlled by restricting the flow of mixture into the cylinders, known as throttling. This inevitably incurred pumping losses thus reducing the efficiency of the overall system.

To overcome this problem engine designers have developed injection system where the fuel is injected directly into the cylinder. Such engines are alternatively known as direct injection spark ignition (DISI), direct injection gasoline (DIG), gasoline direct injection (GDI), etc. Injecting directly into the combustion chamber allows for some degree of stratification of the charge thus allowing an overall lean mixture whilst having a local rich or stoichiometric mixture to facilitate reliable combustion. This injection strategy however means that the fuel injector is subjected to higher temperatures and pressures. This increases the likelihood of forming deposits from the high temperature degradation of the fuel, the fact that the injector is in the combustion chamber also exposes the injector to combustion gases which may contain partially oxidised fuel and or soot particles which may accumulate, increasing the level of deposits. The ability to provide good atomisation of fuel and precise control of fuel flow rates and injection duration are critical to the optimum performance of these engine designs. The radically different operating environment of the fuel injector poses a whole new set of design constraints on the development of an effective fuel additive package. Mixture stratification can also result in combustion occurring in local rich regions leading to the formation of soot particles which can increase combustion chamber deposits. Because liquid fuel is injected into the combustion chamber there is a greater risk of liquid impingement on the combustion chamber surfaces, particularly the piston crown. Liquid fuel on the combustion chamber surfaces can undergo thermal decomposition leading to gum formation and thus increase the rate of build-up of combustion chamber deposits.

An additional problem arising from injecting the fuel directly into the combustion chamber is that fuel impingement on the inlet valves is significantly reduced. The use of fuel containing detergents was relied upon to remove the deposits that build up on the inlet valve tulip as a result of lubricating oil passing down the valve stem and from combustion gases passing back into the inlet system during the initial part of the inlet valve opening event. In a direct injection engine the only possibility for fuel to impinge on the inlet valve tulip is from early injection and late inlet valve closing. This therefore makes it extremely difficult for a fuel borne detergent to have a significant effect on inlet valve deposits.

Effective control of deposits in a direct injection spark ignition gasoline engine is, therefore, a challenging task. Knowledge gained in using additives in other contexts, for example in gasoline engines using carburettors or in gasoline engines using an individual, common, fuel injector, or fuel injectors in the inlet port of each cylinder, or in diesel engines, appear to be of little assistance in achieving effective control of deposits in a direct injection spark ignition gasoline engine.

The particular difficulties in achieving effective control of deposits in a direct injection spark ignition gasoline engine are known in the art. For example they are also explained in WO 01/42399, US 7112230, US 7491248 and WO 03/78553.

In a first aspect the present invention provides a method of controlling deposits in a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted:

(i) a detergent compound which is the reaction product of a carboxylic acid-derived acylating agent and an amine; and

(ii) optionally, one or more additional components selected from: a) carrier oils comprising an optionally esterified polyether b) polyetheramines c) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms d) nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine e) aromatic esters of a polyalkylphenoxyalkanol.

In a second aspect the present invention provides a method of improving the efficiency of a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted: (i) a detergent compound which is the reaction product of a carboxylic acid-derived acylating agent and an amine; and

(ii) optionally, one or more additional components selected from a) - e) described above.

In a third aspect the present invention provides a method of improving the fuel economy of a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted:

Preferably the compounds (i) and (ii) (when present) are present in the fuel in the fuel storage tank which supplies the engine. Although they could be mixed into the fuel in the storage tank, preferably they are present in bulk fuel which is pumped into the storage tank.

Controlling deposits in the specification is intended to cover one or more of: reducing existing deposits ("clean-up"); reducing deposit formation ("keep-clean"); modifying deposits so as to reduce their negative effects.

It has surprisingly been found that the detergent compositions used in this invention achieve good control of deposits even in the demanding context of the direct injection spark ignition gasoline engine.

This control of deposits may lead to a significant reduction in maintenance costs and/or an increase in power and/or an improvement in fuel economy.

(i) DETERGENT COMPOUND

A number of suitable acylated, nitrogen-containing compounds having a hydrocarbyl substituent of at least 8 carbon atoms and made by reacting a carboxylic acid acylating agent with an amino compound are known to those skilled in the art. In such compositions the acylating agent is linked to the amino compound through an imido, amido, amidine or acyloxy ammonium linkage. The hydrocarbyl substituent of at least 8 carbon atoms may be in either the carboxylic acid acylating agent derived portion of the molecule or in the amino compound derived portion of the molecule, or both. Preferably, however, it is in the acylating agent portion. The acylating agent can vary from formic acid and its acylating derivatives to acylating agents having high molecular weight aliphatic substituents of up to 5,000, 10,000 or 20,000 carbon atoms. The amino compounds can vary from ammonia itself to amines typically having aliphatic substituents of up to about 30 carbon atoms, and up to 1 1 nitrogen atoms.

A preferred class of acylated amino compounds suitable for use in the present invention are those formed by the reaction of an acylating agent having a hydrocarbyl substituent of at least 8 carbon atoms and a compound comprising at least one primary or secondary amine group. The acylating agent may be a mono- or polycarboxylic acid (or reactive equivalent thereof) for example a substituted succinic, phthalic or propionic acid and the amino compound may be a polyamine or a mixture of polyamines, for example a mixture of ethylene polyamines. Alternatively the amine may be a hydroxyalkyl-substituted polyamine. The hydrocarbyl substituent in such acylating agents preferably comprises at least 10, more preferably at least 12, for example 30 or 50 carbon atoms. It may comprise up to about 200 carbon atoms. Preferably the hydrocarbyl substituent of the acylating agent has a number average molecular weight (Mn) of from160 to 5000, preferably from170 to 2800, for example from 250 to 1500, preferably from 500 to 1500 and more preferably 500 to 1 100. An Mn of 700 to 1300 is especially preferred. In a particularly preferred embodiment, the hydrocarbyl substituent has a number average molecular weight of 700 - 1000.

Illustrative of hydrocarbyl substituent based groups containing at least eight carbon atoms are n-octyl, n-decyl, n-dodecyl, tetrapropenyl, n-octadecyl, oleyl, chloroctadecyl, triicontanyl, etc. The hydrocarbyl based substituents may be made from homo- or interpolymers (e.g. copolymers, terpolymers) of mono- and di-olefins having 2 to 10 carbon atoms, for example ethylene, propylene, butane-1 , isobutene, butadiene, isoprene, 1-hexene, 1-octene, etc. Preferably these olefins are 1- monoolefins. The hydrocarbyl substituent may also be derived from the halogenated (e.g. chlorinated or brominated) analogs of such homo- or interpolymers. Alternatively the substituent may be made from other sources, for example monomeric high molecular weight alkenes (e.g. 1-tetra-contene) and chlorinated analogs and hydrochlorinated analogs thereof, aliphatic petroleum fractions, for example paraffin waxes and cracked and chlorinated analogs and hydrochlorinated analogs thereof, white oils, synthetic alkenes for example produced by the Ziegler-Natta process (e.g. poly(ethylene) greases) and other sources known to those skilled in the art. Any unsaturation in the substituent may if desired be reduced or eliminated by hydrogenation according to procedures known in the art.

The term "hydrocarbyl" as used within this specification denotes a group having a carbon atom directly attached to the remainder of the molecule and having a predominantly aliphatic hydrocarbon character. Suitable hydrocarbyl based groups may contain non-hydrocarbon moieties. For example they may contain up to one non- hydrocarbyl group for every ten carbon atoms provided this non-hydrocarbyl group does not significantly alter the predominantly hydrocarbon character of the group. Those skilled in the art will be aware of such groups, which include for example hydroxyl, halo (especially chloro and fluoro), alkoxyl, alkyl mercapto, alkyl sulphoxy, etc. Preferred hydrocarbyl based substituents are purely aliphatic hydrocarbon in character and do not contain such groups.

The hydrocarbyl-based substituents are preferably predominantly saturated, that is, they contain no more than one carbon-to-carbon unsaturated bond for every ten carbon-to-carbon single bonds present. Most preferably they contain no more than one carbon-to-carbon non-aromatic unsaturated bond for every 50 carbon-to-carbon bonds present.

Preferred hydrocarbyl-based substituents are poly-(isobutene)s known in the art.

Conventional polyisobutenes and so-called "highly-reactive" polyisobutenes are suitable for use in the invention. Highly reactive polyisobutenes in this context are defined as polyisobutenes wherein at least 50%, preferably 70% or more, of the terminal olefinic double bonds are of the vinylidene type as described in EP0565285. Particularly preferred polyisobutenes are those having more than 80 mol% and up to 100 mol% of terminal vinylidene groups such as those described in EP1344785.

Amino compounds useful for reaction with these acylating agents include the following:

(1 ) polyalkylene polyamines of the general formula: (R³)₂N[U-N(R³)]_nR³

wherein each R³ is independently selected from a hydrogen atom, a hydrocarbyl group or a hydroxy-substituted hydrocarbyl group containing up to about 30 carbon atoms, with proviso that at least one R³ is a hydrogen atom, n is a whole number from 1 to 10 and U is a C1 -18 alkylene group. Preferably each R³ is independently selected from hydrogen, methyl, ethyl, propyl, isopropyl, butyl and isomers thereof. Most pprreeffeerraabbllyy eeaacchh RR³³ iiss ethyl or hydrogen. U is preferably a C1-4 alkylene group, most preferably ethylene.

Specific examples of polyalkylene polyamines (1 ) include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, tri(tri- methylene)tetramine, pentaethylenehexamine, hexaethylene-heptamine, 1 ,2- propylenediamine, and other commercially available materials which comprise complex mixtures of polyamines. For example, higher ethylene polyamines optionally containing all or some of the above in addition to higher boiling fractions containing 8 or more nitrogen atoms etc.

Specific examples of polyalkylene polyamines (1 ) which are hydroxyalkyl-substituted polyamines include N-(2-hydroxyethyl) ethylene diamine, N, N' -bis(2-hydroxyethyl) ethylene diamine, N-(3-hydroxybutyl) tetramethylene diamine, etc.

(2) heterocyclic-substituted polyamines including hydroxyalkyl-substituted polyamines wherein the polyamines are as described above and the heterocyclic substituent is selected from nitrogen-containing aliphatic and aromatic heterocycles, for example piperazines, imidazolines, pyrimidines, morpholines, etc.

Specific examples of the heterocyclic-substituted polyamines (2) are N-2-aminoethyl piperazine, N-2 and N-3 amino propyl morpholine, N-3(dimethyl amino) propyl piperazine, 2-heptyl-3-(2-aminopropyl) imidazoline, 1 ,4-bis (2-aminoethyl) piperazine, 1-(2-hydroxy ethyl) piperazine, and 2-heptadecyl-1-(2-hydroxyethyl)-imidazoline, etc. (3) aromatic polyamines of the general formula: Ar(NR³ ₂)_y

wherein Ar is an aromatic nucleus of 6 to 20 carbon atoms, each R³ is as defined above and y is from 2 to 8.

Specific examples of the aromatic polyamines (3) are the various isomeric phenylene diamines, the various isomeric naphthalene diamines, etc.

4) The amine reactant may alternatively be a compound of general formula R²R³NH where each of R² and R³ independent represents a hydrocarbyl group (as defined herein), preferably a hydrocarbon group (as defined herein), or a hydrogen atom.

Preferably at least one of R² and R³ represents a hydrocarbyl group.

Preferably both R² and R³ represent a hydrocarbyl group.

Suitable terminal groups of a hydrocarbyl group R² and/or R³ may include -CH₃, =CH₂, -OH, -C(O)OH and derivatives thereof. Suitable derivatives include esters and ethers. Preferably a hydrocarbyl group R² and/or R³ does not contain a terminal amine.

A preferred hydrocarbyl group for each of R² and R³ is a group of the formula

-[R⁴NHJ_pR⁵X wherein R⁴ is an alkylene group having from 1 to 10 carbons, preferably from 1 to 5, preferably 1 to 3 carbons, preferably 2 carbons; wherein R⁵ is an alkylene group having from 1 to 10 carbons, preferably from 1 to 5, preferably 1 to 3 carbons, preferably 2 carbons; wherein p is an integer from 0 to 10; wherein X is selected from -CH₃, -CH₂=CH₂, -OH, and -C(O)OH.

A preferred hydrocarbyl group for each of R² and R³ is a group of the formula

-[(CH₂)_qNH]_p(CH₂)_rX wherein p is an integer from 0 to 10, preferably 1 to 10, preferably from 1 to 5, preferably from 1 to 3, preferably 1 or 2; wherein q is an integer from 1 to 10, preferably 1 to 10, preferably from 1 to 5, preferably from 1 to 3, preferably 1 or 2; wherein r is an integer from 1 to 10, preferably 1 to 10, preferably from 1 to 5, preferably from 1 to 3, preferably 1 or 2; and wherein X is selected from -CH₃, -CH₂=CH₂, -OH, and -C(O)OH.

Preferably X is -CH₃, or -OH.

Further amines which may be used in this invention include compounds derived from amines selected from ammonia, butylamine, aminoethylethanolamine, aminopropan-2-ol, 5-aminopentan-1-ol, 2-(2-aminoethoxy)ethanol, monoethanolamine, 3-aminopropan-1 -ol, 2-((3-aminopropyl)amino)ethanol, dimethylaminopropylamine, and N-(alkoxyalkyl)-alkanediamines including N-(octyloxyethyl)-1 ,2-diaminoethane and N-(decyloxypropyl)-N-methyl-1 ,3- diaminopropane.

Specific examples of amines which may be used in this invention and having a tertiary amino group can include but are not limited to: N,N-dimethyl- aminopropylamine, N, N- diethyl-aminopropylamine, N,N-dimethyl- amino ethylamine. The nitrogen or oxygen containing compounds capable of condensing with the acylating agent and further having a tertiary amino group can further include amino alkyl substituted heterocyclic compounds such as 1-(3-aminopropyl)imidazole and 4- (3-aminopropyl)morpholine, 1- (2-aminoethyl)piperidine, 3,3-diamino-N- methyldi-propylamine, and 3'3- aminobis(N,N-dimethylpropylamine). Other types of compounds capable of condensing with the acylating agent and having a tertiary amino group include alkanolamines including but not limited to triethanolamine, trimethanolamine, N, N- dimethylaminopropanol, N,N-diethylaminopropanol, N, N- diethylaminobutanol, N, N, N- tris(hydroxyethyl)amine and N,N,N-tris(hydroxymethyl)amine.

Many patents have described useful acylated nitrogen compounds including U.S. Pat. Nos. 3,172,892; 3,219,666; 3,272,746; 3,310,492; 3,341 ,542; 3,444,170; 3,455,831 ; 3,455,832; 3,576,743; 3,630,904; 3,632,51 1 ; 3,804,763, 4,234,435 and US6821307.

A preferred acylated nitrogen-containing compound of this class is that made by reacting a poly(isobutene)-substituted succinic acid-derived acylating agent (e.g., anhydride, acid, ester, etc.) wherein the poly(isobutene) substituent has between about 12 to about 200 carbon atoms and the acylating agent has from 1 to 5, preferably from 1 to 3, preferably 1 or 2, succinic-derived acylating groups; with a mixture of ethylene polyamines having 3 to about 9 amino nitrogen atoms, preferably about 3 to about 8 nitrogen atoms, per ethylene polyamine and about 1 to about 8 ethylene groups. These acylated nitrogen compounds are formed by the reaction of a molar ratio of acylating agent : amino compound of from 10:1 to 1 :10, preferably from 5:1 to 1 :5, more preferably from 2:1 to 1 :2 and most preferably from 2:1 to 1 :1. In especially preferred embodiments, the acylated nitrogen compounds are formed by the reaction of acylating agent to amino compound in a molar ratio of from 1.8:1 to 1 :1.2, preferably from 1.6:1 to 1 :1.2, more preferably from 1.4:1 to 1 :1.1 and most preferably from 1.2:1 to 1 :1. This type of acylated amino compound and the preparation thereof is well known to those skilled in the art and are described in the above-referenced US patents.

Another type of acylated nitrogen compound belonging to this class is that made by reacting the afore-described alkylene amines with the afore-described substituted succinic acids or anhydrides and aliphatic mono-carboxylic acids having from 2 to about 22 carbon atoms. In these types of acylated nitrogen compounds, the mole ratio of succinic acid to mono-carboxylic acid ranges from about 1 :0.1 to about 1 :1. Typical of the monocarboxylic acid are formic acid, acetic acid, dodecanoic acid, butanoic acid, oleic acid, stearic acid, the commercial mixture of stearic acid isomers known as isostearic acid, tolyl acid, etc. Such materials are more fully described in U.S. Pat. Nos. 3,216,936 and 3,250,715.

A further type of acylated nitrogen compound suitable for use in the present invention is the product of the reaction of a fatty monocarboxylic acid of about 12-30 carbon atoms and the afore-described alkylene amines, typically, ethylene, propylene or trimethylene polyamines containing 2 to 8 amino groups and mixtures thereof. The fatty mono-carboxylic acids are generally mixtures of straight and branched chain fatty carboxylic acids containing 12-30 carbon atoms. Fatty dicarboxylic acids could also be used. A widely used type of acylated nitrogen compound is made by reacting the afore-described alkylene polyamines with a mixture of fatty acids having from 5 to about 30 mole percent straight chain acid and about 70 to about 95 percent mole branched chain fatty acids. Among the commercially available mixtures are those known widely in the trade as isostearic acid. These mixtures are produced as a byproduct from the dimerization of unsaturated fatty acids as described in U.S. Pat. Nos. 2,812,342 and 3,260,671. The branched chain fatty acids can also include those in which the branch may not be alkyl in nature, for example phenyl and cyclohexyl stearic acid and the chloro-stearic acids. Branched chain fatty carboxylic acid/alkylene polyamine products have been described extensively in the art. See for example, U.S. Pat. Nos. 3,1 10,673; 3,251 ,853; 3,326,801 ; 3,337,459; 3,405,064; 3,429,674; 3,468,639; 3,857,791. These patents are referenced for their disclosure of fatty acid/polyamine condensates for their use in lubricating oil formulations.

Suitably the molar ratio of the acylating group of an acylating agent defined above and the reacting amine group of said amine is in the range 0.5-5:1 , preferably 0.8-2.2:1. At a ratio of 1 :1 the reaction product is called mono-PIBSI, and at a ratio of 2:1 it is called bis-PIBSI and requires a polyamine as reactant.

Preferred nitrogen-containing detergents for use herein include: the compound formed by reacting a polyisobutylene succinic anhydride (PIBSA) having a PIB molecular weight of 900 to 1100, for example approximately 1000; with aminoethyl ethanolamine or tetraethylene pentamine; and the compound formed by reacting a PIBSA having a PIB molecular weight of 650 to 850, for example about 750 with tetraethylene pentamine. In each case the ratio of PIBSA to amine is preferably from 2.5:1 to 0.9:1 , preferably from 2.2:1 to 1 :1.

In some preferred embodiments, detergent compound (i) may be used without additional components a)-e). In other preferred embodiments, detergent compound (i) is used with one or more additional components selected from: a) carrier oils comprising an optionally esterified polyether b) polyetheramines c) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms d) nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine e) aromatic esters of a polyalkylphenoxyalkanol

Preferably the ratio of detergent compound (i) to additional components (ii) when present, is 1 :100 to 100:1 , preferably 1 :50 : 50:1 , preferably 1 :15 to 20:1 preferably 1 :15 to 10:1 preferably 1 :10 to 10:1 preferably 1 :5 to 5:1. Preferably the ratio of detergent compound (i) to carrier oil a) when present, is 1 :100 to 100:1 , preferably 1 :50 : 50:1 , preferably 1 :15 to 20:1 preferably 1 :15 to 10:1 preferably 1 :10 to 10:1 preferably 1 :5 to 5:1 , preferably 1 :2 to 2:1.

Preferably the ratio of the total of compound (i) and components b), c), d) and e) to carrier oil b) when present, is 1 :100 to 100:1 , preferably 1 :50 : 50:1 , preferably 1 : 15 to 20:1 preferably 1 :15 to 10:1 preferably 1 :10 to 10:1 preferably 1 :5 to 5:1 , preferably 1 :2 to 2:1.

All ratios are weight ratios on an active basis. The total amount of compound(s) (i) and each compound a) - e) specified in the respective definition is to be taken into account.

a) CARRIER OIL

The carrier oil may have any suitable molecular weight. A preferred molecular weight is in the range 500 to 5000.

In a preferred aspect the polyether carrier oil is a mono end-capped polypropylene glycol. Preferably the end cap is a group consisting of or containing a hydrocarbyl group having up to 30 carbon atoms. More preferably the end cap is or comprises an alkyl group having from 4 to 20 carbon atoms or from 12 to 18 carbon atoms.

The alkyl group may be branched or straight chain. Preferably it is a straight chain group.

Further hydrocarbyl end capping groups include alkyl-substituted phenyl, especially where the alkyl substituent(s) is or are alkyl groups of 4 to 20 carbon atoms, preferably 8 to 12, preferably straight chain.

The hydrocarbyl end capping group may be attached to the polyether via a linker group. Suitable end cap linker groups include an ether oxygen atom (-O-), an amine group (-NH-), an amide group (-CONH-), or a carbonyl group -(C=O)-.

In a preferred embodiment the carrier oil is a polypropyleneglycol monoether of the formula:

where R⁶ is straight chain C₁-C30 alkyl, preferably C₄-C₂O alkyl, preferably Ci₂-Ci₈ alkyl; and n is an integer of from 10 to 50, preferably 10 to 30, more preferably 12 to 20.

Such alkyl polypropyleneglycol monoethers are obtainable by the polymerisation of propylene oxide using an aliphatic alcohol, preferably a straight chain primary alcohol of to 20 carbon atoms, as an initiator. If desired a proportion of the propyleneoxy units may be replaced by units derived from other C₂-Cβ alkylene oxides, e.g. ethylene oxide or isobutylene oxide, and are to be included within the term "polypropyleneglycol". The initiator may also be a phenol or alkyl phenol of the formula R⁷OH, a hydrocarbyl amine or amide of the formula R⁷NH₂ or R⁷CONH, respectively, where R⁷ is CrC₃₀ hydrocarbyl group, preferably a saturated aliphatic or aromatic hydrocarbyl group such as alkyl, phenyl or phenalkyl etc. Preferred initiators include long chain alkanols giving rise to the long chain polypropyleneglycol monoalkyl ethers.

In a further aspect the polypropyleneglycol may be an ester (R⁶COO) group where R⁶ is defined above. In this aspect the carrier oil may be a polypropyleneglycol monoester of the formula

where R⁶ and n are as defined above and R8 is a CrC₃₀ hydrocarbyl group, preferably an aliphatic hydrocarbyl group, and more preferably CrCi₀ alkyl.

b) Polvetheramines

Suitable hydrocarbyl-substituted polyoxyalkylene amines or polyetheramines employed in the present invention are described in the literature (for example US 6217624 and US 4288612) and have the general formula: R l

or a fuel-soluble salt thereof; wherein R is a hydrocarbyl group having from about 1 to about 30 carbon atoms; R1 and R2 are each independently hydrogen or lower alkyl having from about 1 to about 6 carbon atoms and each R1 and R2 is independently selected in each -O-CHR1 -CHR2 - unit; A is amino, N-alkyl amino having about 1 to about 20 carbon atoms in the alkyl group, N,N-dialkyl amino having about 1 to about 20 carbon atoms in each alkyl group, or a polyamine moiety having about 2 to about 12 amine nitrogen atoms and about 2 to about 40 carbon atoms; x is an integer from about 5 to about 100; and y is 0 or 1.

In Formula I, above, R is a hydrocarbyl group having from about 1 to about 30 carbon atoms. Preferably, R is an alkyl or alkylphenyl group. More preferably, R is an alkylphenyl group, wherein the alkyl moiety is a straight or branched chain alkyl of from about 1 to about 24 carbon atoms.

Preferably, one of R1 and R2 is lower alkyl of 1 to 4 carbon atoms, and the other is hydrogen. More preferably, one of R1 and R2 is methyl or ethyl, and the other is hydrogen.

In general, A is amino, N-alkyl amino having from about 1 to about 20 carbon atoms in the alkyl group, preferably about 1 to about 6 carbon atoms, more preferably about 1 to about 4 carbon atoms; N,N-dialkyl amino having from about 1 to about 20 carbon atoms in each alkyl group, preferably about 1 to about 6 carbon atoms, more preferably about 1 to about 4 carbon atoms; or a polyamine moiety having from about 2 to about 12 amine nitrogen atoms and from about 2 to about 40 carbon atoms, preferably about 2 to 12 amine nitrogen atoms and about 2 to 24 carbon atoms. More preferably, A is amino or a polyamine moiety derived from a polyalkylene polyamine, including alkylene diamine. Most preferably, A is amino or a polyamine moiety derived from ethylene diamine or diethylene triamine. Preferably, x is an integer from about 5 to about 50, more preferably from about 8 to about 30, and most preferably from about 10 to about 25.

The polyetheramines will generally have a molecular weight in the range from about 600 to about 10,000.

Fuel-soluble salts of the compounds of formula I can be readily prepared for those compounds containing an amino or substituted amino group and such salts are contemplated to be useful for preventing or controlling engine deposits. Suitable salts include, for example, those obtained by protonating the amino moiety with a strong organic acid, such as an alkyl- or arylsulfonic acid. Preferred salts are derived from toluenesulfonic acid and methanesulfonic acid.

Other suitable polyetheramines are those taught in US 5089029 and US 51 12364. c) Hvdrocarbyl-Substituted Amines

Hydrocarbyl-substituted amines suitable for use in the present invention are well known to those skilled in the art and are described in a number of patents. Among these are U.S. Pat. Nos. 3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,755,433 and 3,822,209. These patents describe suitable hydrocarbyl amines for use in the present invention including their method of preparation.

d) Nitrogen-Containing Condensates of Phenols, Aldehydes, and Amino Compounds Phenol/aldehyde/amine condensates useful as detergent in the present invention include those generically referred to as Mannich condensates. Such compounds can be made by reacting simultaneously or sequentially at least one active hydrogen compound for example a hydrocarbon-substituted phenol (e.g., an alkyl phenol wherein the alkyl group has at least an average of about 8 to 200; preferably at least 12 up to about 200 carbon atoms), having at least one hydrogen atom bonded to an aromatic carbon, with at least one aldehyde or aldehyde-producing material (typically formaldehyde or a precursor thereof) and at least one amino or polyamino compound having at least one NH group. The amino compounds include primary or secondary monoamines having hydrocarbon substituents of 1 to 30 carbon atoms or hydroxyl- substituted hydrocarbon substituents of 1 to about 30 carbon atoms. Another type of typical amino compound are the polyamines described above in relation to acylated nitrogen-containing compounds. One class of preferred nitrogen containing detergent for use in the present invention are those formed by a Mannich reaction between:

(a) an aldehyde;

(b) a polyamine; and

(c) an optionally substituted phenol.

Any aldehyde may be used as aldehyde component (a) but preferred are aliphatic aldehydes. Preferably the aldehyde has 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms. Most preferably the aldehyde is formaldehyde.

Polyamine component (b) may be selected from any compound including two or more amine groups. Preferably the polyamine is a polyalkylene polyamine. Suitable polyalkylene polyamines are as previously defined herein.

Preferably the polyamine has 1 to 15 nitrogen atoms, preferably 1 to 10 nitrogen atoms, more preferably 3 to 8 nitrogen atoms.

Preferably the polyamine is selected from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, and heptaethyleneoctamine. Most preferably it is tetraethylenepentamine or ethylene diamine.

Commercially available sources of polyamines typically contain mixtures of isomers and/or oligomers, and products prepared from these commercially available mixtures fall within the scope of the present invention.

Optionally substituted phenol component (c) may be substituted with 0 to 4 groups on the aromatic ring (in addition to the phenol OH). For example it may be a tri- or di- substituted phenol. Most preferably component (c) is a mono-substituted phenol. Substitution may be at the ortho, and/or meta, and/or para position(s).

Preferably the phenol component (c) carries one or more optionally substituted alkyl substituents. Preferably the component (c) is a monoalkyl phenol, especially a para- substituted monoalkyl phenol. In some preferred embodiments component (c) comprises an alkyl substituted phenol in which the phenol carries one or more alkyl chains having a total of less than 28 carbon atoms, preferably less than 24 carbon atoms, preferably less than 20 carbon atoms, more preferably less than 18 carbon atoms, preferably less than 16 carbon atoms and most preferably less than 14 carbon atoms.

For example component (c) may have alkyl substituents having from 4 to 20 carbons atoms, preferably 6 to 18, more preferably 8 to 16, especially 10 to 14 carbon atoms. In some particularly preferred embodiments, component (c) is a phenol having a C12 alkyl substituent.

In other preferred embodiments component (c) is substituted with a larger alkyl chain, for example those having in excess of 20 carbon atoms. Particularly preferred compounds are those in which the phenol is substituted with a hydrocarbyl residue made from homo or interpolymers (e.g. copolymers, terpolymers) of mono- and di- olefins having 2 to 10 carbon atoms, for example ethylene, propylene, butane-1 , isobutene, butadiene, isoprene, 1-hexene, 1-octene, etc. Preferably these olefins are 1-monoolefins. The hydrocarbyl substituent may also be derived from the halogenated (e.g. chlorinated or brominated) analogs of such homo- or interpolymers. Alternatively the substituent may be made from other sources which are well known to those skilled in the art.

Especially preferred are phenols substituted with a polyisobutene residue of molecular weight of between 250 and 5000, for example between 500 and 1500, preferably between 650 and 1200, most preferably between 700 and 1000.

Suitable detergents include the reaction product obtained by reacting components (a),

(b) and (c) in a ratio of from 5:1 :5 to 0.1 :1 :0.1 , more preferably from 3:1 :3 to 0.5:1 :0.5.

Components (a) and (b) are preferably reacted in a ratio of from 4:1 to 1 :1 (aldehyde:polyamine), preferably from 2:1 to 1 :1. Components (a) and (c) are preferably reacted in a ratio of from 4:1 to 1 :1 (aldehyde:phenol), more preferably from 2:1 to 1 :1.

Especially preferred detergents are those formed by reacting components (a), (b) and

(c) in a ratio of 1 :1 :1 or 2:1 :2. Mixtures of these compounds may also be used. Typically component (b) comprises a mixture of isomers and/or oligomers. Component (c) may also comprise a mixture of isomers and/or homologues.

Other preferred detergents used in the present invention are typically formed by reacting components (a), (b) and (c) in a molar ratio of 2 parts (a) to 1 part (b) ± 0.2 parts (b), to 1.5 parts (c) ± 0.3 parts (c); preferably approximately 2:1 :1.5 (a : b : c).

e) aromatic esters of a polvalkylphenoxyalkanol

The aromatic ester component which may be employed additive composition is an aromatic ester of a polyalkylphenoxyalkanol and has the following general formula:

(I)

or a fuel-soluble salt thereof wherein R is hydroxy, nitro or -(CH2)x-NR5R6, wherein R5 and R6 are independently hydrogen or lower alkyl having 1 to 6 carbon atoms and x is 0 or 1 ;

R1 is hydrogen, hydroxy, nitro or -NR7R8 wherein R7 and R8 are independently hydrogen or lower alkyl having 1 to 6 carbon atoms;

R2 and R3 are independently hydrogen or lower alkyl having 1 to 6 carbon atoms; and R4 is a polyalkyl group having an average molecular weight in the range of about 450 to 5,000.

The preferred aromatic ester compounds employed in the present invention are those wherein R is nitro, amino, N-alkylamino, or -CH2NH2 (aminomethyl). More preferably, R is a nitro, amino or -CH2NH2 group. Most preferably, R is an amino or -CH2NH2 group, especially amino. Preferably, R1 is hydrogen, hydroxy, nitro or amino. More preferably, R1 is hydrogen or hydroxy. Most preferably, R1 is hydrogen. Preferably, R4 is a polyalkyl group having an average molecular weight in the range of about 500 to 3,000, more preferably about 700 to 3,000, and most preferably about 900 to 2,500. Preferably, the compound has a combination of preferred substituents.

Preferably, one of R2 and R3 is hydrogen or lower alkyl of 1 to 4 carbon atoms, and the other is hydrogen. More preferably, one of R2 and R3 is hydrogen, methyl or ethyl, and the other is hydrogen. Most preferably, R2 is hydrogen, methyl or ethyl, and R3 is hydrogen.

When R and/or R1 is an N-alkylamino group, the alkyl group of the N-alkylamino moiety preferably contains 1 to 4 carbon atoms. More preferably, the N-alkylamino is N-methylamino or N-ethylamino.

Similarly, when R and/or R1 is an NN-dialkylamino group, each alkyl group of the N, N- dialkylamino moiety preferably contains 1 to 4 carbon atoms. More preferably, each alkyl group is either methyl or ethyl. For example, particularly preferred N, N- dialkylamino groups are N,N-dimethylamino, N-ethyl-N-methylamino and N, N- diethylamino groups.

A further preferred group of compounds are those wherein R is amino, nitro, or - CH2NH2 and R1 is hydrogen or hydroxy. A particularly preferred group of compounds are those wherein R is amino, R1 , R2 and R3 are hydrogen, and R4 is a polyalkyl group derived from polyisobutene.

It is preferred that the R substituent is located at the meta or, more preferably, the para position of the benzoic acid moiety, i.e., para or meta relative to the carbonyloxy group. When R1 is a substituent other than hydrogen, it is particularly preferred that this R1 group be in a meta or para position relative to the carbonyloxy group and in an ortho position relative to the R substituent. Further, in general, when R1 is other than hydrogen, it is preferred that one of R or R1 is located para to the carbonyloxy group and the other is located meta to the carbonyloxy group. Similarly, it is preferred that the R4 substituent on the other phenyl ring is located para or meta, more preferably para, relative to the ether linking group.

The aromatic esters e) will generally have a molecular weight in the range from about 700 to about 3,500, preferably from about 700 to about 2,500. Fuel-soluble salts of the compounds e) can be readily prepared for those compounds containing an amino or substituted amino group and such salts are contemplated to be useful for preventing or controlling engine deposits. Suitable salts include, for example, those obtained by protonating the amino moiety with a strong organic acid, such as an alkyl- or arylsulfonic acid. Preferred salts are derived from toluenesulfonic acid and methanesulfonic acid.

When the R or R1 substituent is a hydroxy group, suitable salts can be obtained by deprotonation of the hydroxy group with a base. Such salts include salts of alkali metals, alkaline earth metals, ammonium and substituted ammonium salts. Preferred salts of hydroxy-substituted compounds include alkali metal, alkaline earth metal and substituted ammonium salts.

ADDITIVE COMPOSITION

Compounds (i) and, where present, (ii) may be added separately or they may be added as a single package. All references to treat rates and ratios of compounds herein apply to additive compounds whether added separately or when added as a package.

Preferably the compounds (i) and (ii) (when (ii) is present) and preferably also any further fuel additive compounds present for other purposes, are provided as an additive composition, in a common detergent package.

The detergent compound (i) may be present in amount to provide the necessary and/or required handling and/or functional properties. Typically the detergent compound (i) (including solvent of production) is present in an amount of from 10 to 60% by weight, preferably 30 to 60% by weight, based on the total additive composition. Typically the detergent compound (i) (excluding solvent of production) is present in an amount of from 6 to 36% by weight, preferably 18 to 36% by weight, based on the total additive composition.

The carrier oil a) when present may be present in an amount of from 2 to 40% by weight, based on the total additive composition.

In a preferred aspect the additive composition which may be used in the present invention further comprises a solvent. The solvent may be a hydrocarbon solvent having a boiling point in the range 66 to 32O⁰C. Suitable solvents include xylene, toluene, white spirit, mixtures of aromatic solvents boiling in the range 18O⁰C to 27O⁰C

If present the amount of solvent to be incorporated will depend upon the desired final viscosity of the additive composition. Typically the solvent will be present in an amount of from 20 to 70% of the final additive composition on a weight basis.

In a preferred aspect an additive composition useful in the present invention comprises a solvent and a co-solvent. The co-solvent may be typically present in an amount of 1-2 wt%. Suitable co-solvents include aliphatic alcohols (such as CAS no 66455-17-2)

Additive compositions useful in the present invention may contain a number of minor ingredients, often added to meet specific customer requirements. Included amongst these are dehazers, usually an alkoxylated phenol formaldehyde resin, added to minimise water interaction and to prevent a hazy or cloudy appearance of the fuel composition, and a corrosion inhibitor, usually of the type comprising a blend of one or more fatty acids and/or amines. Either or both may be present in the additive compositions useful in the present invention in amounts ranging from 0.1 to 5%, or 1 to 3% each, based on the total weight of the additive composition.

Other minor ingredients which may be added include anti-oxidants, anti-icing agents, metal deactivators, lubricity additives, friction modifiers, dehazers, corrosion inhibitors, dyes, cetane improvers, anti-valve-seat recession additives, stabilisers, demulsifiers, antifoams, odour masks, and conductivity improvers and combustion improvers. These may be added in amounts according to conventional practice, typically ranging from 0.001%, up to 2 or 3%, by weight, based on the total weight of the fuel composition.

In general terms the total amount of such minor functional ingredients in the additive composition will not exceed about 10% by weight, more usually not exceeding about 5% by weight based on the total weight of the additive composition.

Such further ingredients could in principle be added separately to compound(s) (i) but it is preferred for reasons of convenience and consistency of dosing to add them with compound(s) (i) and - when present, with compounds (ii) - in a common additive composition.

FUEL COMPOSITION

By the term "gasoline", it is meant a liquid fuel for use with spark ignition engines (typically or preferably containing primarily or only C4-C12 hydrocarbons) and satisfying international gasoline specifications, such as ASTM D-439 and EN228. The term includes blends of distillate hydrocarbon fuels with oxygenated components such as ethanol, as well as the distillate fuels themselves. The fuels may contain, in addition to the additive composition of the invention, any of the other additives conventionally added to gasoline as, for example, antiknock additives, anti-icing additives, octane requirement additives, lubricity additives etc."

Preferably the composition is present in the fuel in an amount to provide on a weight basis, from 50 to 500 ppm detergent and, when present, 30 to 500 ppm carrier oil.

USE

In a fourth aspect the present invention provides the use of (i) the detergent compound defined above, and, optionally of (ii) one or more additional components selected from a) - e) described above; added into gasoline to control deposits in a direct injection spark ignition gasoline engine.

In a fifth aspect the present invention provides the use of (i) the detergent compound defined above, and, optionally of (ii) one or more additional components selected from a) - e) described above; added into gasoline to improve efficiency in a direct injection spark ignition gasoline engine.

In a sixth aspect the present invention provides the use of (i) the detergent compound defined above, and, optionally of (ii) one or more additional components selected from a) - e) described above; added into gasoline to provide improved fuel economy in a direct injection spark ignition gasoline engine.

NOVEL COMPOSITIONS Certain compositions defined above may be new; these may include certain additive compositions containing certain compounds (i) and (ii); certain additive compositions containing certain compounds (i) and (ii); certain fuel compositions containing gasoline and certain compounds (i) and (ii) - whether added separately to the gasoline or together, as an additive composition.

The present invention will now be described by way of Example only.

EXAMPLES

Detergent compound A1

1000 mwt high reactive PIB derived PIBSA (i.e. polyisobutenyl succinic anhydride) (633.2g) was stirred with Shellsol AB (421 g) in a 1 litre oil jacketed reactor equipped with an overhead stirrer, thermometer and Dean & Stark trap. Whilst still at room temperature aminoethylethanolamine (60.6g) was added in one aliquot with continued stirring. An immediate exotherm was noted. The reaction mix was heated to 130- 150⁰C for three hours whilst removing water. 1058g of product was isolated. Analysis of the detergent compound A1 showed it to contain 39%m/m solvent, 1.47%m/m nitrogen.

Additive package 1

Detergent compound A1 was blended with a carrier oil compound - a) in claim 1 - namely a linear C13 linear alcohol polyether with 13 propylene oxy (PO) units, to produce an additive composition intended to be added to gasoline which is to be used in a direct injection spark ignition gasoline engine, at a treat rate of 175 mg/l of the detergent compound A1 and 175 mg/l of the carrier oil a), both as actives.

Detergent compound A2

1000 mwt high reactive PIB derived PIBSA (633.2g, 0.58 mol) was stirred with aromatic solvent (Caromax 20, 421 g) in a 1 litre oil jacketed reactor equipped with an overhead stirrer, thermometer and Dean & Stark trap. Whilst still at room temperature aminoethylethanolamine (60.6g, 0.58 mol) was added in one aliquot with continued stirring. An immediate exotherm was noted. The reaction mix was heated to 130- 150⁰C for three hours whilst removing water. 1058g of product was isolated. The mol ratio of pibsa : amine was approximately 1 :1. Detergent compound A3

1000 mwt high reactive PIB derived PIBSA (4712g) was stirred with aromatic solvent (Caromax 20, 3337g) in a 1 litre oil jacketed reactor equipped with an overhead stirrer, thermometer and Dean & Stark trap. A polyethylene polyamine mixture of average composition approximating to tetraethylene pentamine (363.2g, 1.92 mol) was added in one aliquot with continued stirring at 50⁰C. An immediate exotherm was noted. The reaction mix was heated to 160⁰C for three hours whilst removing water. 8343g of product was isolated. The mol ratio of pibsa : amine was approximately 2:1.

Detergent compound A4

Detergent compound A4 is a 60% active ingredient solution (in aromatic solvent) of a polyisobutenyl succinimide obtained from the condensation reaction of a polyisobutenyl succinic anhydride (PIBSA) derived from polyisobutene of Mn approximately 750 with a polyethylene polyamine mixture of average composition approximating to tetraethylene pentamine. The mol ratio of pibsa : amine was approximately 1 :1.

Additional component B

A reactor was charged with dodecylphenol (277.5 kg, 1.06 kmoles), ethylenediamine (43.8 kg, 0.73 kmoles) and Caromax 20 (196.4 kg). The mixture was heated to 90°C and formaldehyde solution, 36.6 wt% (1 19.7kg, 1.46 kmoles) charged over 1 hour. The temperature was increased to 140⁰C for 3 hours and water removed under vacuum. Analysis of the product - d) in claim 1 - showed it to contain 35%m/m solvent. In this example the molar ratio of aldehyde(a) : amine(b) : phenol(c) was approximately 2:1 :1.45.

Additional component C

Additional component C is a commercially available carrier oil compound namely a linear C13 linear alcohol polyether with 15 PO (propyleneoxy) units (component a) in claim 1 ).

Additive Packages

Additive packages were prepared using the above additives together with additional aromatic solvent as shown in Table 1. Table 1

Basefuel

An E5 98 RON basefuel was prepared by blending 95% by volume of a reference gasoline RF-83-A-91/B16 with 5% by volume of dehydrated ethanol denatured with cyclohexane. Analytical data for the reference gasoline is given in Table 2.

Table 2 Analysis of RF-83-A-91/B16

RON = Research Octane Number MON = Motor Octane Number

Test Fuels

Test Fuels were prepared by blending 1000 mg/kg of Additive Packages 2-5 into the same batch of base fuels. This resulted in Fuel Compositions 2-5 containing the concentrations of additives set out in Table 3 below. Table 3

GDI Engine Tests

Engine tests were performed using the APL GDI Nozzle Coking test.

This test was designed to check the ability of fuels and/or additives to keep injector nozzles of GDI-engines clean. The engine used is the VW FSI 036. K / ARR / VW -1 ,4 litre VW Lupo 2002. Engine details are as follows:

• Number of Cylinders: 4

• Displacement: 1398 cm3

• Norn. Power: 77 kW

• Norn. Torque: 130 Nm

• Fuel: RON 98

• Spark Plugs: VAG 101 000 068 AA

• Coolant: 50 % Water / 50 % G 12 litres VW TL 774/D

The injectors have one sprayhole with 0.55 mm diameter.

The test uses a 4 stage alternating program, including part load with stratified combustion and full load at maximum torque speed. Each cycle of 4 stages has a 30 min running time. The test duration is around 50 hours (= 100 cycles). The total fuel consumption is around 750 litres per test. The selected engine oil is LM Top Tec 4200 5W-30, a first fill oil for this engine type.

After the test, the engine inlet manifold is dissassembled, so the nozzles can be removed for evaluation.

The deposits are rated visually, following a scale from 0 to 7. 0: Clean or a very limited number of single spots visible

7: Surface completely covered with deposits with thickness and structured surface

The rating shows the best existing surface / deposit formation called "Minimum", the worst case of deposit formation called "Maximum" and an Average value, that reflects the overall appearance and distribution of little and heavy deposits.

The evaluation is made by a Scanning Electron Microscope (SEM) that shows the topography and distribution of the deposits around and in the sprayhole. An analysis of the injector deposits by Energy Dispersive X-Ray (EDX) Elemental Analysis is also performed. In particular, the iron content is considered to be the most important parameter with new and clean nozzles showing values around 50% iron and injectors with heavy deposits showing values around 5% iron.

Results of these engine tests for Fuel Compositions 2-5 are shown in Tables 4 and 5.

Table 4 Visual Rating of Injection Nozzle Orifice Deposits

Table 5 EDX Elemental Analysis - % Weight Iron

Claims

1. A method of controlling deposits in a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted:

2. A method of improving the efficiency of a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted:

3. A method of improving the fuel economy of a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted:

4. Use of

(ii) optionally, one or more additional components selected from: a) carrier oils comprising an optionally esterified polyether b) polyetheramines c) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms d) nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine e) aromatic esters of a polyalkylphenoxyalkanol, added into gasoline to control deposits in a direct injection spark ignition gasoline engine.

5. Use of

(ii) optionally, one or more additional components selected from: a) carrier oils comprising an optionally esterified polyether b) polyetheramines c) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms d) nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine e) aromatic esters of a polyalkylphenoxyalkanol, added into gasoline to improve efficiency in a direct injection spark ignition gasoline engine.

6. Use of

(ii) optionally, one or more additional components selected from: a) carrier oils comprising an optionally esterified polyether b) polyetheramines c) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms d) nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine e) aromatic esters of a polyalkylphenoxyalkanol, added into gasoline to provide improved fuel economy in a direct injection spark ignition gasoline engine.

7. A method or use according to any one of the preceding claims wherein the detergent compound (i) is a polyisobutenyl succinimide.

8. A method or use according to any one of the preceding claims wherein the polyether carrier oil a) has a molecular weight in the range 500 to 5000.

9. A method or use according to any one of the preceding claims wherein the polyether carrier oil a) is a mono end-capped polypropylene glycol.

10. A method or use according to claim 29 wherein the carrier oil a) is a polypropyleneglycol monoether of the formula:

where R :>6 is straight chain Ci₂-Ci₈ alkyl; and n is an integer of from 10 to 30.

1 1. A method or use according to any one of the preceding claims wherein the compounds (i) and (ii) when present when present are provided together in a composition which optionally further comprises a solvent.