Composition and Method for Reducing Friction in Internal Combustion Engines

Abstract

A fuel composition comprising a combustible fuel, an effective friction reducing amount of at least one C6 to C30 aliphatic amine, and a detergent package is disclosed, as well as a method of reducing the amount of friction in an internal combustion engine by adding the fuel composition to the engine.

Description

This application claims the benefit of U.S. Provisional Application No. 61/288,463 filed Dec. 21, 2009, the entirety of which is expressly incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to friction modifiers and, more particularly, to a new fuel composition and method for reducing friction in internal combustion engines.

BACKGROUND OF THE INVENTION

Much of the focus over the past twenty years has been devoted to fuel additives which control deposit formation in the fuel induction systems of spark ignition internal combustion engines. These deposit control additives have been formulated to effectively control carbonaceous deposits on the fuel injectors, the intake valves and the combustion chamber in an effort to maintain or achieve engine cleanliness.

As crude consumption and fuel costs steadily increased over the past decade, consumers have expressed a growing interest and have placed a greater emphasis on the importance of improvements in vehicle fuel economy. In particular, there has been a strong consumer interest for additives which can offer reduced engine wear, lower emissions, and improved fuel economy. Unfortunately, the deposit control additives provide very little friction reduction performance at typical concentrations used in commercial fuels. Therefore, no additional fuel economy benefit would be expected over and above that achieved through deposit control within the engine.

During this same time period, there have been many advances in engine design directed toward better fuel economy and more power generation (specifically more horsepower and acceleration). Conventional port-fuel injection (PFI) is the primary fuel delivery technology used in gasoline engines. PFI engines inject gasoline into the intake port along with the intake air to form a homogeneous mixture for combustion. This is done in an attempt to optimize the combustion of the fuel and provide improved engine performance. In addition, many other engine management control technologies have been developed to further optimize the combustion process for improved fuel economy in PFI engines.

More recently, gasoline direct injection (GDI) engines have been developed to provide improved fuel economy while maintaining or generating more engine-out power. The GDI engine injects gasoline directly into the combustion chamber separate from the air intake which allows the engine management system to better optimize the combustion process according to the load conditions. Both PFI and GDI engines require fuel additives to control deposits in the injectors, intake valves and combustion chamber. In addition, further fuel economy improvement could be achieved by reducing the friction between the cylinder liner and piston ring interface, the valve train and the fuel pump, especially in GDI engines. Therefore, there is a need in the petroleum industry to develop a fuel and fuel additive package that addresses the engine deposit and friction reduction requirements of PFI and GDI engines.

Due to the fact that lubricants have traditionally been used to minimize engine friction, and an estimated 25 to 50% of the frictional losses of an engine occur at the cylinder liner and piston ring interface, the lubricant industry was the first to focus on reducing engine friction and improving fuel economy. Improvements in fuel economy have been achieved through the lowering of the motor oil viscosity. However, at conditions where the engine is working hard (high load and high temperature), such as hard acceleration or going up hill, lower viscosity oils can produce very thin lubricant films which may increase the potential for metal-to-metal contact and lead to wear and higher friction, i.e., lower fuel economy. To help reduce this contact and improve engine lubrication under these boundary layer conditions, both inorganic and organic friction modifiers have been utilized, but GF-4 motor oil requirements have reduced the level of inorganic friction modifiers allowed due to phosphorus deactivation of the catalytic converter. This has forced the lubricant industry to rely more heavily on organic friction modifiers.

Organic friction modifiers are compounds that can affect the boundary layer conditions experienced by the cylinder liner and piston ring interface under these severe engine operating conditions. These types of friction modifiers are surface active and produce a protective coating on the metal surface of the engine by forming a monolayer through the interaction of the metal surface with the polar end of the friction modifier. Subsequent layers of the friction modifier can then build up to provide friction reduction in the boundary layer and help to prevent the two surfaces and their asperities from contacting each other. The challenge in overcoming the frictional design limitations, however, lies in identifying a friction modifier which can influence the boundary layer properties without leading to undesirable effects, such as intake valve deposits and oil thickening.

The application of organic friction modifiers in combustible fuels has been pursued for some time with minimal success. Friction modifier additives and detergents commonly added to combustible fuels are generally higher molecular weight compounds that may not be completely burned during the combustion process within spark ignition engines. As a result, some of the additive interacts with the lubricant oil film present in the combustion cylinder. This interaction allows some of the additive to become mixed with the lubricant. As the lubricant oil film is replenished, it becomes mixed with fresh lubricant from the main lubricant reservoir and some of the absorbed additive migrates past the piston rings and into the oil pan. As a result, there is a slow transfer of additive from the fuel to the lubricant. Depending on the driving cycle, the amount of additive that is transferred from the fuel to the lubricant can be as high as about 30%. Based on typical friction modifier additive concentrations expected for gasoline, this level of transfer may lead to friction modifier concentrations in the lubricant of up to about 0.5 wt % over a 5,000 mile lube drain interval. Therefore, the addition of an organic friction modifier to a combustible fuel can impact the cylinder liner and piston ring frictional interaction directly within the combustion chamber and can also accumulate in a lubricant to improve the frictional properties in other parts of the engine drive train contacted by the motor oil (e.g., valve train, cam shaft, bearings, etc.). This transfer of the friction modifier is known in the art and taught, for example, in WO 01/72390 A2, which describes the delivery mechanism by which a fuel born friction modifier can be transferred to the cylinder liner/piston ring interface and can accumulate in the lubricating oil sump, thus resulting in improved lubrication throughout the engine.

Accordingly, it would be desirable to provide a new fuel composition which contains a combustible fuel, a detergent package and a friction modifier that has a strong affinity for metal surfaces, but not so strong as to leave deposits. It would also be desirable to provide a method for reducing the amount of friction in an internal combustion engine by adding the new fuel composition to the engine to positively impact the friction of the cylinder liner and piston ring interface and the drive train of the engine, and lead to lower emissions, higher fuel economy and increased net horsepower.

SUMMARY OF THE INVENTION

In accordance with the present invention, the fuel composition comprises a combustible fuel, an effective friction reducing amount of at least one C₆ to C₃₀ aliphatic amine, and a detergent package.

In another aspect, the invention provides a fuel additive composition comprising an effective friction reducing amount of at least one C₆ to C₃₀ aliphatic amine and a detergent package.

The invention also provides a method of reducing the amount of friction in an internal combustion engine comprising the step of adding to the engine a fuel composition comprising a combustible fuel, an effective friction reducing amount of at least one C₆ to C₃₀ aliphatic amine, and a detergent package.

The inventive method effectively reduces the amount of friction in an internal combustion engine by adding the fuel composition of the present invention to the engine, thus leading to lower emissions, higher fuel economy, and increased net horsepower.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a new fuel composition and method for reducing the amount of friction in an internal combustion engine. In accordance with the invention, the fuel composition comprises a combustible fuel, an effective friction reducing amount of at least one C₆ to C₃₀ aliphatic amine, and a detergent package. The fuel composition is added to the internal combustion engine to effectively reduce the amount of friction in the engine.

In accordance with the invention, the combustible fuels which may be used include gasoline and diesel fuel, with the preferred fuel being gasoline. Gasoline comprises blends of C₄-C₁₂ hydrocarbons which boil in the range of 25° C. to 225° C., and satisfy international gasoline specifications, such as ASTM D-4814 and EN228. These gasoline blends typically contain mixtures of normal and branched paraffins, olefins, aromatics and naphthenic hydrocarbons, and other liquid hydrocarbon containing components suitable for spark ignition gasoline engines, such as conventional alcohols and ethers.

The gasoline can be derived from petroleum crude oil by conventional refining and blending processes, such as straight run distillation, hydrocracking, fluid catalytic cracking, thermal cracking, and various reforming technologies.

The C₆ to C₃₀ aliphatic amines which may be used as friction modifiers in the practice of the invention include saturated fatty acid amines, unsaturated fatty acid amines, and mixtures thereof. Preferable C₆ to C₃₀ aliphatic amines include, but are not limited to, octyl-, decyl-, dodecyl-, tetradecyl-, hexadecyl-, hexadecenyl-, octadecyl-, octadecenyl-amines, and mixtures thereof. Tallow amines are particularly preferred C₆ to C₃₀ aliphatic amines, with hydrogenated tallow amines being most preferred. An example of a suitable hydrogenated tallow amine is Armeen®HTD, available from Akzo Nobel Surface Chemistry LLC.

The fuel composition preferably contains an effective friction reducing amount of the C₆ to C₃₀ aliphatic amine in the range of from about 1 ppm to about 2000 ppm (parts per million). More preferably, the amount of the C₆ to C₃₀ aliphatic amine present in the fuel composition is in the range of from about 5 ppm to about 1000 ppm, with about 10 ppm to about 500 ppm being most preferred.

The detergent packages which may be used in the practice of the present invention are well known to those skilled in the art and commercially available. Suitable commercial detergent packages include, but are not limited to, Keropur® and Kerocom® packages available from BASF A.G., HiTEC® packages available from Afton Chemical Corporation, and OGA® packages available from Chevron Oronite Company LLC.

The detergent packages typically include at least one deposit control additive, a corrosion inhibitor, a carrier fluid, and a solvent. Some commercially available detergent packages do not contain a corrosion inhibitor and may be used in the practice of the present invention, however, it is preferred that a corrosion inhibitor be included. The appropriate amount of each component in the detergent package will vary depending upon the specific engine performance benefit being sought and can be readily determined by those skilled in the art.

The detergent package typically contains at least one high molecular weight nitrogen-containing deposit control additive. Examples of such deposit control additives include polyalkylene amines, polyalkylene succinimides, Mannich bases, and polyether amines. The preferred deposit control additive for use in the present invention is a polyisobutylene (FIB) amine. Examples of suitable PIB-amines are taught in U.S. Pat. No. 4,832,702, the disclosure of which is incorporated herein by reference.

The corrosion inhibitors which may be utilized in the practice of the present invention include, but are not limited to, monomers, dimers, and trimers of long chain organic acids, and various esters, imides, thiadiazoles, and triazoles.

The carrier fluids which may be used in the detergent package are preferably compatible with the combustible fuel and have the ability to dissolve or disperse the components of the detergent package. Examples of conventional carrier fluids include mineral oils and synthetic oils, such as poly a-olefin oligomers, polyethers, polyether amines, and carboxylic esters of long chain alkanols.

There are various alcohols and aromatic hydrocarbons which may be used as solvents in the practice of the present invention. Examples of suitable solvents include xylenes, toluene, tetrahydrofuran, isopropanol isobutylcarbinol, and n-butanol; and petroleum hydrocarbon solvents, such as naphtha and the like.

The fuel composition may comprise another friction modifier in accordance with the present invention. It was discovered that when certain friction modifier combinations are utilized, greater coefficient of friction reduction is achieved than when either friction modifier is used alone. In particular, when a glycerol monoalkyl ether, more preferably, a glycerol monooleyl ether is combined with a hydrogenated tallow amine, the interaction of the two friction modifiers leads to significantly improved lubricity.

The fuel composition preferably contains an effective friction reducing amount of the glycerol monoalkyl ether in the range of from about 1 ppm to about 1000 ppm. More preferably, the amount of the glycerol monoalkyl ether present in the fuel composition is in the range of from about 5 ppm to about 500 ppm, with about 10 ppm to about 250 ppm being most preferred.

The fuel composition may be added to an internal combustion engine by any conventional method and can be used in internal combustion engines that burn liquid fuel, especially spark-ignited gasoline engines encompassing carbureted, PFI and GDI, as well as in vehicles containing compression-ignited engines, such as diesel engines. When combustion of the fuel composition is achieved in the internal combustion engine, the amount of friction in the engine is effectively reduced, thus leading to lower emissions, higher fuel economy, and increased net horsepower.

In another aspect of the present invention, a fuel additive composition containing an effective friction reducing amount of at least one C₆ to C₃₀ aliphatic amine and a detergent package is provided. All of the suitable components which may be used in the fuel additive composition and their respective amounts are the same as those described above with respect to the fuel composition. The fuel additive may be combined with a combustible fuel in any conventional manner generally known to those having ordinary skill in the art to which this invention pertains and then added to an internal combustion engine to effectively reduce the amount of friction in the engine.

EXAMPLES

The following examples are intended to be illustrative of the present invention and to teach one of ordinary skill how to make and use the invention. These examples are not intended to limit the invention or its protection in any way.

Example 1

An SRV® instrument was utilized to determine the performance of a number of friction modifier additives. The SRV instrument measures the coefficient of friction and wear scar of a lubricant resulting from the oscillation of a ball on a disc at a constant set of conditions. SRV reciprocation tests were done using a commercial Castrol GTX® 5W30 (GF-4) motor oil that was spiked with various commercially available organic friction modifier additives.

The organic friction modifier additives tested were glycerol monooleate (GMO), which was obtained from Oronite Chemical Company, oleylamide (Crodamide® O), obtained from Croda Chemicals, glycerol monooleyl ether (FM-618C), obtained from Adeka USA, and hydrogenated tallow amine (Armeen HTD), obtained from Akzo Nobel Surface Chemistry LLC. Test samples were prepared by mixing 0.5 grams of the organic friction modifier with 99.5 grams of the Castrol GTX 5W30 motor oil.

The SRV instrument uses a steel ball as the upper test piece and a steel disk as the lower test piece. An oil sample was placed on the disk, a load was applied to the ball from the top, and the ball was vibrated parallel to the disk as the ball was pressed against the disk. The lateral load applied to the disk was measured to calculate the coefficient of friction. The coefficient of friction was taken as the average of the data for a particular temperature. The SRV test conditions were 50 N load, 50 Hz oscillation, 1 mm stroke and 1 hour duration. The initial temperature was set to 80° C. for the first 30 minutes of testing and then rapidly raised to 120° C. for the final 30 minutes. This procedure provided some indication of the temperature dependence of the additive's effect on friction reduction at temperatures expected to be encountered between the cylinder liner and piston ring. The results of the testing are shown below in Table 1.

TABLE 1
Comparison of SRV Results
	Treat	Coefficient of	Coefficient of Friction
Friction Modifier	Rate	Friction	% Reduction
Additive	(wt %)	80° C.	120° C.	80° C.	120° C.
None	N/A	0.143	0.145	N/A	N/A
GMO	0.5	0.137	0.137	4.2	5.5
Crodamide O	0.5	0.128	0.126	10.5	13.1
FM-618C	0.5	0.131	0.130	8.4	10.3
Armeen HTD	0.5	0.128	0.122	10.5	15.9

The data in Table 1 illustrate the superior performance of the Armeen HTD (hydrogenated tallow amine) relative to other known friction modifier additives. These data show that at 120° C., the coefficient of friction can be lowered by approximately 16% relative to that of a commercial Castrol GTX motor oil meeting the GF-4 specifications through the use of the Armeen HTD additive. The coefficient of friction values are significantly tower than those of the GMO additive (at both temperatures) and show improvement over the high temperature data for the Crodamide O additive. Both the GMO and Crodamide O additives are well-known friction modifier chemistries and have been used extensively in motor vehicle lubricants.

Although the effect of the Armeen HTD friction modifier was measured in motor oil, one skilled in the art would understand that the addition of a friction modifier to a combustible fuel results in the accumulation of the friction modifier in the motor oil over the typical drain interval of the vehicle. Therefore, testing of the friction modifier in the motor oil is a reliable alternative to more expensive and complex engine tests.

Therefore, the inventive composition and method can effectively reduce the amount of friction within an internal combustion engine (in particular, the cylinder liner and piston ring interface and the drive train) by producing improved lubricity. The lower friction in turn can lead to lower emissions, higher fuel economy, and an increase in net horsepower.

Example 2

Intake valve deposit measurements were carried out on a Ford 2.3 L engine dynamometer Intake Valve Deposit (IVD) clean-up test stand according to a modified version of the standard ASTM D6201 procedure. Clean valves were installed in the engine and then a retail gasoline which contained the minimum amount of detergent additive as required by the US EPA (i.e., the lowest additive concentration or LAC) was run for 50 hours following a Coordinating Research Council (CRC) drive cycle. The engine was disassembled, the valve weights were measured, and then reassembled to determine the clean-up performance of the test fuels using a 100 hour test following the CRC drive cycle. The IVD clean-up performance results of a comparative detergent package (345 ppmv) containing a PIB-amine, corrosion inhibitor, carrier fluid, solvent and dye, and the detergent package in combination with the Armeen HTD additive are shown below in Table 2.

TABLE 2
Comparison of IVD Clean-Up Results
				IVD
Friction Modifier	Treat Rate	Average IVD	Average IVD	Clean-Up,
Additive	(ppmv)	Dirty-Up, mg	Clean-Up, mg	%
None	N/A	155	93	40
Armeen HTD	125	204	84	59

The results illustrated in Table 2 demonstrate the significantly better IVD control and detergent clean-up afforded by the combination of the detergent package and the Armeen HTD friction modifier, as compared to the detergent package alone. Thus, the Armeen HTD additive is a desirable friction modifier since it has a strong affinity for metal surfaces, but does not leave deposits.

Example 3

The same SRV testing of the friction modifier additized Castrol GTX 5W30 motor oil performed above in Example 1 was conducted in this example to determine the performance of a combination of additives, namely FM-618C and Armeen HTD. Additional test samples were prepared by mixing 0.2 grams of the organic friction modifier with 99.8 grams of the Castrol GTX 5W30 motor oil. All of the coefficient of friction results from Example 1 and from the testing in this example of the combination of the FM-618C and Armeen HTD friction modifier additives are shown below in Table 3.

TABLE 3
Comparison of SRV Results
Friction Modifier		Coefficient of Friction
Additive	Treat Rate (wt %)	80° C.	120° C.
None	N/A	0.143	0.145
GMO	0.5	0.137	0.137
Crodamide O	0.5	0.128	0.126
FM-618C	0.2	0.145	0.145
FM-618C	0.5	0.131	0.130
Armeen HTD	0.2	0.132	0.129
Armeen HTD	0.5	0.128	0.122
FM-618C	0.2	0.126	0.118
Armeen HTD	0.5

The data in Table 3 demonstrate that the combination of a glycerol monooleyl ether (FM-618C) and a hydrogenated tallow amine (Armeen HTD) provides greater coefficient of friction reductions than either additive alone. The data also show that the FM-618C and Armeen HTD additive combination provides the lowest coefficient of friction values at both temperatures tested, and that the values are lower than those of either GMO or Crodamide O, both of which are well-known friction modifier chemistries. In addition, this improvement is contrary to the simple additive effect since the coefficient of friction values for the FM-618C additive are higher than those of the Armeen HTD additive, and the combination of the two friction modifier additives resulted in a lower set of coefficient of friction values.

Therefore, the inventive composition and method improves lubricity and helps reduce the amount of friction within an internal combustion engine through the synergistic interactions of two different friction modifier chemistries added via the fuel. This synergistic behavior effectively lowers the amount of friction within the cylinder liner and piston ring interface and the drive train of the internal combustion engine. The lower friction in turn can lead to lower emissions, higher fuel economy, and an increase in net horsepower.

While the present invention is described above in connection with preferred or illustrative embodiments, these embodiments are not intended to be exhaustive or limiting of the invention. Rather, the invention is intended to cover all alternatives, modifications and equivalents included within its spirit and scope, as defined by the appended claims.

Claims

1. A fuel composition comprising:

a. a combustible fuel;

b. an effective friction reducing amount of at least one C6 to C30 aliphatic amine; and

c. a detergent package.

2. The composition of claim 1 wherein the combustible fuel is selected from the group consisting of gasoline and diesel fuel.

3. The composition of claim 1 wherein the C6 to C30 aliphatic amine is selected from the group consisting of saturated fatty acid amines, unsaturated fatty acid amines, and mixtures thereof.

4. The composition of claim 3 wherein the C6 to C30 aliphatic amine is selected from the group consisting of octyl-, decyl-, dodecyl-, tetradecyl-, hexadecyl-, hexadecenyl-, octadecyl-, octadecenyl-amines, and mixtures thereof.

5. The composition of claim 4 wherein the C6 to C30 aliphatic amine is a tallow amine.

6. The composition of claim 5 wherein the C6 to C30 aliphatic amine is a hydrogenated tallow amine.

7. The composition of claim 1 wherein the amount of the C6 to C30 aliphatic amine is in the range of from about 1 ppm to about 2000 ppm.

8. The composition of claim 1 wherein the amount of the C6 to C30 aliphatic amine is in the range of from about 5 ppm to about 1000 ppm.

9. The composition of claim 1 wherein the amount of the C6 to C30 aliphatic amine is in the range of from about 10 ppm to about 500 ppm.

10. The composition of claim 1 wherein the detergent package comprises:

a. at least one deposit control additive;

b. a corrosion inhibitor;

c. a carrier fluid; and

d. a solvent

11. The composition of claim 1 further comprising an effective friction reducing amount of at least one glycerol monoalkyl ether.

12. The composition of claim 11 wherein the glycerol monoalkyl ether is a glycerol monooleyl ether.

13. The composition of claim 11 wherein the amount of the glycerol monoalkyl ether is in the range of from about 1 ppm to about 1000 ppm.

14. The composition of claim 11 wherein the amount of the glycerol monoalkyl ether is in the range of from about 5 ppm to about 500 ppm.

15. The composition of claim 11 wherein the amount of the glycerol monoalkyl ether is in the range of from about 10 ppm to about 250 ppm.

16. A fuel additive composition comprising:

a. an effective friction reducing amount of at least one C6 to C30 aliphatic amine, and

b. a detergent package.

17. The composition of claim 16 wherein the C6 to C30 aliphatic amine is a hydrogenated tallow amine.

18. The composition of claim 16 wherein the amount of the C6 to C30 aliphatic amine is in the range of from about 1 ppm to about 2000 ppm.

19. The composition of claim 16 wherein the detergent package comprises:

a. at least one deposit control additive;

b. a corrosion inhibitor;

c. a carrier fluid; and

d. a solvent.

20. The composition of claim 16 further comprising an effective friction reducing amount of at least one glycerol monooleyl ether.

21. The composition of claim 20 wherein the amount of the glycerol monooleyl ether is in the range of from about 1 ppm to about 1000 ppm.

22. A method of reducing the amount of friction in an internal combustion engine comprising the step of adding to the engine a fuel composition comprising a combustible fuel, an effective friction reducing amount of at least one C6 to C30 aliphatic amine, and a detergent package.

23. The method of claim 22 wherein the C6 to C30 aliphatic amine is a hydrogenated tallow amine.

24. The method of claim 22 wherein the amount of the C6 to C30 aliphatic amine is in the range of from about 1 ppm to about 2000 ppm.

25. The method of claim 22 wherein the detergent package comprises:

a. at least one deposit control additive;

b. a corrosion inhibitor;

c. a carrier fluid; and

d. a solvent.

26. The method of claim 22 further comprising an effective friction reducing amount of at least one glycerol monooleyl ether.

27. The method of claim 26 wherein the amount of the glycerol monooleyl ether is in the range of from about 1 ppm to about 1000 ppm.