Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic nitrogen compound
Reexamination Certificate
2002-05-23
2004-07-06
McAvoy, Ellen M (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic nitrogen compound
C508S554000
Reexamination Certificate
active
06759375
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to lubricating an internal combustion diesel engine which is equipped with an exhaust gas recirculation system (exhaust gas recycle) with a lubricant which includes an amide, leading to lower sump temperature of the lubricant.
Various techniques to abate emissions of such materials as nitrogen oxides and particulate matter, from engines, and in particular, heavy duty diesel engines, have been also developed. One of these methods is the installation of exhaust gas recirculation (EGR) systems. An EGR system recycles part of exhaust gases into the intake air stream. EGR has been used for the control of nitrogen oxide emissions for light duty diesel and gasoline engines. However, this approach has not been widely adopted for heavy duty diesel engines because of various problems, such as decreased durability and reliability of the engine and deterioration of the lubricant which have been associated with EGR. These and related difficulties are believed to arise, in part, because of the increased engine and lubricant temperatures encountered in such engines, due to the recycling of a portion of hot exhaust gas.
The present invention, therefore, addresses the problem of excessive lubricant sump temperature in diesel engines with an exhaust gas recirculation system by including within the lubricant an amide of an aliphatic carboxylic acid. This permits reduction of the lubricant temperature, leading to an increase in its useful lifetime, or, alternatively, recycling of a larger fraction of the exhaust gas without an unacceptable increase in the lubricant temperature.
The use of aliphatic amides as a friction modifier component of engine lubricants is generally known and are disclosed, for example, in U.S. Pat. No. 5,652,201 However, the use of aliphatic amides in engines without EGR has been shown to tend to lead at times to valve train wear, and thus such materials are not often used. It has now been observed that, for reasons that are not entirely understood, valve train wear is not such a problem in engines with EGR when aliphatic amide is present. This opens the possibility for use of such amines, as in the present invention, for the reduction of oil temperature, a possibility which is precluded in practice for engines without EGR.
SUMMARY OF THE INVENTION
The present invention provides a method for lubricating a sump-lubricated internal combustion diesel engine equipped with an exhaust gas recirculation system, comprising supplying to said engine a lubricating oil composition comprising:
(a) an oil of lubricating viscosity;
(b) about 0.05 to about 1 percent by weight of an amide of an aliphatic carboxylic acid, said acid containing 6 to 28 carbon atoms; and
(c) at least one additional additive selected from the group consisting of dispersants, detergents, anti-wear agents;
whereby the oil-sump temperature or the piston liner temperature is reduced under operating conditions, compared to that of a comparable composition without component (b).
DETAILED DESCRIPTION OF THE INVENTION
Various preferred features and embodiments will be described below by way of non-limiting illustration.
The present invention is particularly suitable for use in a diesel engine with exhaust gas recycle, such as a passenger car diesel engine or, especially, a heavy duty diesel engine with exhaust gas recycle. The construction of such engines and such exhaust gas recycle systems is well known and is described in detail, for example, in Leet et al., SAE Technical Paper 980179, “EGR's Effect on Oil Degradation and Intake System Performance,” Feb. 23-26, 1998, especially pages 57-59, and McKinley, SAE Technical Paper 970636, “Modeling Sulfuric Acid Condensation in Diesel Engine EGR Coolers,” Feb. 24-27, 1997, especially page 207; and references cited in each.
Diesel engines typically consume hydrocarbon fuels, normally referred to as diesel fuels. Recently, water-blend fuels (hydrocarbons blended with up to e.g. 20% water, with appropriate emulsifiers and other additives) have been used. The method of the present invention is useful for engines consuming any of these fuels, including low sulfur diesel fuels and diesel fuels obtained from a Fischer-Tropsch process. Low sulfur diesel fuels can contain 15 or less parts per million sulfur.
The present invention relates to sump-lubricated engines, that is, those in which the lubricant is retained in a sump or reservoir from which it is circulated to and through the engine. This is in contrast to systems, characteristic of certain two-stroke cycle engines, in which the lubricant is mixed with the fuel and the fuel-lubricant mixture passes through the engine only once before being consumed.
The engines in which the present invention can be used are typically compression-ignited (diesel) engines. It is especially useful in heavy duty diesel engines, although benefits are also observed in other engines including small diesel engines. The distinction between heavy duty and small diesel engines is principally one of piston displacement within the engine cylinders. Small diesel engines, typically used in passenger cars, particularly in Europe, normally have a displacement of less than 3L, typically up to 2.5L, and commonly below 2L. In contrast, heavy duty diesel engines are typically used in trucks and off-road vehicles and will normally have a displacement of 3L or greater, typically 6 to 12 L or even greater, particularly for certain off-road vehicles.
The first component of the lubricant is an oil of lubricating viscosity, including natural or synthetic or semisynthetic lubricating oils and mixtures thereof. Natural oils include animal oils, vegetable oils, mineral lubricating oils of paraffinic, naphthenic, or mixed types, solvent or acid treated mineral oils, and oils derived from coal or shale. Synthetic lubricating oils include hydrocarbon oils, halo-substituted hydrocarbon oils, alkylene oxide polymers (including those made by polymerization of ethylene oxide or propylene oxide), esters of dicarboxylic acids and a variety of alcohols including polyols, esters of mono-carboxylic acids and polyols, esters of phosphorus-containing acids, polymeric tetrahydrofurans, and silicon-based oils (including siloxane oils and silicate oils). Included are unrefined, refined, and rerefined oils. Specific examples of the oils of lubricating viscosity are described in U.S. Pat. No. 4,326,972.
Lubricating oils have also been categorized as API Groups I, II, III, IV, and V, on the basis of parameters such as sulfur content, saturate content, and viscosity index. Group III oils are generally considered superior, in these categories to Group II, which is turn is superior to Group I. Group IV comprises all polyalphaolefins, and Group V comprises oils not included in the other groups. Group III base oils are also sometimes considered to be synthetic base oils, and for the purposes of this invention they can be considered to be included within the definition of “synthetic base oils.” Group III base oils are defined by the API Base Oil Interchange Guidelines as having the following minimum characteristics: ≦0.03% sulfur, ≧90% saturates, and ≧120 viscosity index. These are generally oils which are derived from natural stocks (as opposed to being derived from synthetic sources), but are so highly refined that they can exhibit the performance and viscosity parameters of other synthetic base oils. The present invention can be used with any of these oils, although it is particularly useful with Groups II, III, and IV or with oils comprising groups III, IV, and V. It is also useful in base oils prepared by a Fischer-Tropsch process.
The lubricating oil will normally comprise the major amount of the composition used for the present invention. Thus it will normally be at least 50% by weight of the composition, preferably about 83 to about 98%, and most preferably about 88 to about 90%.
The lubricant composition will include at least one or more of the additives which are conventional for use in an engine oil lubricant, and
Bardasz Ewa A.
Curtis Thomas T.
Heath Daniel H.
Thomson Peter B.
Esposito Michael F.
McAvoy Ellen M
Shold David M.
The Lubrizol Corporation
LandOfFree
Use of an amide to reduce lubricant temperature does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Use of an amide to reduce lubricant temperature, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of an amide to reduce lubricant temperature will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3228067