Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Nitrogen and heavy metal – or nitrogen and aluminum – in the...
Reexamination Certificate
2000-09-20
2002-09-03
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Nitrogen and heavy metal, or nitrogen and aluminum, in the...
C508S364000, C508S369000, C508S398000, C508S539000, C508S584000
Reexamination Certificate
active
06444624
ABSTRACT:
This invention relates to multigrade lubricating oil compositions that, in particular, give enhanced performance in diesel engine ring-sticking tests.
Lubricating oil compositions (or lubricants) for the crankcase of internal combustion engines are well-known and it is also well-known for them to contain additives (or additive components) to enhance their properties and performance.
Increasingly, the demands of original equipment manufacturers (OEM's) to meet performance criteria dictate the properties of lubricants. One such performance criterion concerns the sticking of piston rings during operation of a compression-ignited (diesel) internal combustion engine. This is usually referred to briefly as “ring-sticking”; it may be measured by the VWTDi test (CEC L-78-T-97).
Other performance criteria of interest include the volatility of the lubricant, the fuel economy performance of the lubricant, and the chlorine content of the lubricant.
The various criteria clearly constrain formulators of lubricants in terms of additive components and amounts, and of basestocks, that may be used.
It has now been surprisingly found, according to this invention, that use of low concentrations of molybdenum, present as an organo molybdenum compound, can give rise to lubricants meeting demanding “ring-sticking” test requirements, whilst, at the same time, meeting other criteria.
A number of references describe the use of oil-soluble molybdenum in lubricants.
See, for example, U.S. Pat. Nos. 4,164,473; 4,176,073; 4,176,074; 4,192,757; 4,248,720; 4,201,683; 4,289,635; and 4,479,883. But none describes use for ameliorating “ring-sticking”.
In a first aspect, the invention is an SAE OW-30 or 5W-30 or 5W-20 multigrade lubricating oil composition having a Noack volatility of less than 15, such as less than 13, preferably less than 11, preferably no lower than 4 or 5% mass loss according to CEC L-40-A-93; and, optionally, an M-111 fuel economy of equal to or greater than 1.5, such as 2.5%, according to CEC L-54-T-96, said composition comprising, or being made by admixing, a major amount of
(A) a basestock of lubricating viscosity that contains from 0 to less than 10, preferably from 0 to less than 5, mass % of a Group I basestock or a Group II basestock or a mixture of Group I and Group II basestocks, other than basestocks that arise from provision of additive components in the composition; and minor amounts of additive components comprising
(B) one or more molybdenum-containing additives in an amount providing not greater than 1000, advantageously not greater than 500, such as not greater than 350 or 300 or 250, such as no lower than 50, ppm by mass of elemental molybdenum in the composition;
(C) one or more calcium detergent additives comprising a calcium salt of an organic acid as a surfactant, in an amount or amounts providing 10 or greater, such as 12 or greater, such as up to 30 or 35, m moles of surfactant per kilogram of the composition;
(D) one or more other lubricant additives selected from ashless dispersants, metal detergents, anti-oxidants, anti-wear agents, and friction modifiers, provided they are different from additives (B) and (C) above; and
(E) one or more viscosity modifiers,
the additive components providing less than 100, such as less than 50, but such as no lower than 5 or 10, ppm by mass of chlorine to the composition.
In a second aspect, the invention is a method of lubricating a compression-ignited internal combustion engine comprising operating the engine and lubricating the engine with a lubricating oil composition according to the first aspect of the invention.
In a third aspect, the invention is a method of reducing the ring-sticking tendencies of a compression-ignited internal combustion engine comprising adding to the engine a lubricating oil composition according to the first aspect of the invention.
In a fourth aspect, the invention is a combination comprising the crankcase of a compression-ignited engine and a lubricating oil composition according to the first aspect of the invention for lubricating the crankcase.
In this specification:
“comprising” or any cognate word is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof;
“major amount” means in excess of 50 mass % of the composition;
“minor amount” means less than 50 mass % of the composition, both in respect of the stated additive and in respect of the total mass % of all of the additives present in the composition, reckoned as active ingredient of the additive or additives;
“oil-soluble” or “dispersible” used herein do not necessarily indicate that the compounds or additives are soluble, dissolvable, miscible, or capable of being suspended in the oil in all proportions. These do mean, however, that they are, for instance, soluble or stably dispersible in oil to an extent sufficient to exert their intended effect in the environment in which the oil is employed. Moreover, the additional incorporation of other additives may also permit incorporation of higher levels of a particular additive, if desired.
The invention also provides the product obtained or obtainable as a result of any reaction between the various additive components of the composition or concentrates, essential as well as customary and optimal, under the conditions of formulation, storage or use:
The features of the invention will now be discussed in more detail as follows:
Multigrade Lubricants
Multigrade lubricants perform over wide temperature ranges. Typically, they are identified by descriptors such as SAE 10W-30 or SAE 5W-30. The first number in the multigrade descriptor is associated with a safe cranking temperature (e.g., +20° C. ) viscosity requirement for that multigrade oil as measured by a cold cranking simulator (CCS) under high shear rates (ASTM D5293). In general, lubricants that have low CCS viscosities allow the engine to crank more easily at lower temperatures and thus improve the ability of the engine to start at those ambient temperatures.
Multiviscosity—grade oils, commonly referred to as “multigrades” are designed to operate over wide temperature ranges and are identified by descriptors such as SAE 10W-30 or SAE 5W-30. Their properties are defined in the Society of Automotive Engineers document SAE J300. This publication defines multigrades in terms of two criteria: Maximum low temperature cranking and pumping viscosities and Maximum and minimum kinematic viscosities at 100° C. and a minimum high-shear viscosity at 150° C. and 10
8
S−1
.
Low temperature properties define which “W” grade shall be assigned to a lubricant and high temperature properties define the “non W” part of the designation. SAE J300 defines a series of W grades with SAE 0W representing the requirements for operation at lowest temperatures. SAE 5W, 10W, 15W, 20W and 25W are also defined, these grades are suitable for progressively higher minimum temperature of operation. Non-W grades are also assigned a numerical designation, these define a scale of increasing high temperature viscosity. This scale starts with SAE 20 and goes through SAE 30, 40 and 50 to the most viscous grade, SAE 60.
This system of viscometric classification of automotive crankcase lubricants finds universal application with the vehicle and lubricant manufacturing industries.
Noack Volatility
Oil volatility has been associated in the technical literature with both oil consumption and exhaust emissions, both of which are undesirable. One method used to measure volatility of a lubricant is the Noack method. Two standardized Noack methods are JPI Method 5S-41-93 and CEC L-40-A-93. Those methods measure the percent mass lost after a sample has been held at a temperature of 250° C. for 60 minutes whilst air is passed through. For the purposes of this invention, all Noack volatility measurements are made using instruments that have been calibrated with a reference fluid.
Fuel Economy
M-111 fuel economy is as measured in accordance
Bell Ian A.
Walker Juliet V.
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