Methods and uses of controlling piston varnish formation in an internal combustion engine

Abstract

The use as a piston varnish controlling additive in a fuel composition for a spark-ignition internal combustion engine or a compression-ignition gasoline internal combustion engine of a combination of: a. a hydrocarbyl-substituted aromatic compound; and b. a polyalkylene amine. The fuel composition may also be used for controlling power output, fuel economy, engine wear, piston ring sticking and blow-by.

1 - 15 . (canceled) 
     
     
         16 . A method of controlling piston varnish formation in a spark-ignition internal combustion engine or a compression-ignition gasoline internal combustion engine which method comprises supplying to the engine a fuel composition which comprises a combination of:
 a. a hydrocarbyl-substituted aromatic compound; and   b. a polyalkylene amine,   the hydrocarbyl-substituted aromatic compound and the polyalkylene amine being present in the fuel composition in an amount such that substantially less piston varnish is formed when the fuel composition is combusted in the engine than when the same fuel composition without the combination of the hydrocarbyl-substituted aromatic compound and the polyalkyleneamine is combusted in the engine.   
     
     
         17 . The method of  claim 16 , wherein the hydrocarbyl-substituted aromatic compound is a Mannich Base additive. 
     
     
         18 . The method of  claim 16 , wherein the polyalkylene amine is a polyisobutylene amine. 
     
     
         19 . The method of  claim 16 , wherein the hydrocarbyl-substituted aromatic compound is present in the fuel composition at a concentration of actives of from about 20 ppm to about 300 ppm. 
     
     
         20 . The method of  claim 16 , wherein the hydrocarbyl substituent of the aromatic compound exhibits a number average molecular weight of from about 700 to about 1500. 
     
     
         21 . The method of  claim 16 , wherein the hydrocarbyl substituent of the aromatic compound is or comprises polyisobutylene. 
     
     
         22 . The method of  claim 16 , wherein the polyalkylene amine is present in the fuel composition at a concentration of actives of from about 50 ppm to about 500 ppm. 
     
     
         23 . The method of  claim 16 , wherein the polyalkylene amine contains a polyalkylene group that exhibits a number average molecular weight of from about 700 to about 1500. 
     
     
         24 . The method of  claim 16 , wherein the weight ratio of actives of the polyalkylene amine:the hydrocarbyl-substituted aromatic compound in the fuel composition is in the range of from about 5:1 to about 1:5. 
     
     
         25 . The method of  claim 16 , wherein the engine is a spark-ignition internal combustion engine. 
     
     
         26 . The method of  claim 16 , wherein the engine is a compression-ignition gasoline internal combustion engine. 
     
     
         27 . The method of  claim 16 , wherein the at least one polyalkylene amine is present in the fuel composition at a concentration of actives of from 100 ppm to 500 ppm. 
     
     
         28 . The method of  claim 16 , wherein the at least one polyalkylene amine is present in the fuel composition at a concentration of actives of from 160 ppm to 500 ppm. 
     
     
         29 . The method of  claim 16 , wherein the at least one hydrocarbyl-substituted aromatic compound is present in the fuel composition at a concentration of actives of from 70 ppm to 200 ppm. 
     
     
         30 . The method of  claim 16 , wherein
 the at least one hydrocarbyl-substituted aromatic compound is present in the fuel composition at a concentration of actives of from 70 ppm to 200 ppm; and   the at least one polyalkylene amine is present in the fuel composition at a concentration of actives of from 160 ppm to 500 ppm.   
     
     
         31 . The method of  claim 16 , wherein the hydrocarbyl-substituted aromatic compound is a Mannich Base additive, and the polyalkylene amine is a polyisobutylene amine. 
     
     
         32 . A method of reducing the piston varnish forming tendency of a fuel composition for use in a spark-ignition internal combustion engine or a compression-ignition gasoline internal combustion engine which method comprises incorporating into the fuel composition in one or more steps:
 a. a hydrocarbyl-substituted aromatic compound; and   b. a polyalkylene amine   
       to produce a fuel composition which comprises said additives in combination and which on use in said engine produces less piston varnish than the piston varnish formed when using in said engine the fuel composition without said combination of additives. 
     
     
         33 . The method of  claim 32 , wherein the hydrocarbyl-substituted aromatic compound is a Mannich Base additive and the polyalkylene amine is a polyisobutylene amine. 
     
     
         34 . The method of  claim 32 , wherein the hydrocarbyl-substituted aromatic compound is present in the fuel composition at a concentration of actives of from about 20 ppm to about 300 ppm, and the polyalkylene amine is present in the fuel composition at a concentration of actives of from about 50 ppm to about 500 ppm. 
     
     
         35 . A method of controlling at least one of power output, fuel economy, engine wear, piston ring sticking and blow-by in a spark-ignition internal combustion engine or a compression-ignition gasoline internal combustion engine which method comprises supplying to the engine a fuel composition which comprises a combination of:
 a. a hydrocarbyl-substituted aromatic compound; and   b. a polyalkylene amine.