Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heavy metal or aluminum in an organic phosphorus compound...
Reexamination Certificate
1998-03-09
2001-07-17
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heavy metal or aluminum in an organic phosphorus compound...
C508S436000, C508S440000, C508S567000
Reexamination Certificate
active
06262000
ABSTRACT:
This invention relates to a composition and a method of improving the antiwear performance of power transmitting fluids, particularly continuously variable transmissions (CVT's). This is accomplished in a CVT fluid compatible with conventional friction modifiers.
The continuing search for methods to improve overall vehicle fuel economy has identified power transmitting units as a source of energy loss. For example, the torque converter, used between the engine and automatic transmission, since it is a fluid coupling, is not 100% efficient as compared to a solid disk type clutch.
One method of improving overall vehicle fuel economy is by the use of CVT's. A CVT is a power transmitting device which operates by transferring power between driving and driven pulley-like conical sheaves via a steel belt. The conical sheaves are actuated in manner which allows continuous engagement of the power drive system while the vehicle is traveling in a particular direction, i.e. either forward or reverse. The CVT is very effective at capturing lost energy and is capable of enhancing vehicular fuel economy upwards between 10-20 percent above vehicles with conventional gear driven power transmitting devices.
We have found additive combinations which meet the very exacting antiwear requirements of CVT's and are compatible with conventional friction modifiers.
SUMMARY OF THE INVENTION
This invention relates to a composition and method of improving the antiwear performance of a power transmitting fluid comprising:
(1) a major portion of a lubricating oil; and
(2) an antiwear improving effective amount of an additive combination comprising:
(a) an amine phosphate;
(b) an organic polysulfide;
(c) a zinc salt of a phosphorothioic acid ester; and
(d) optionally, a friction modifier.
DETAILED DESCRIPTION OF THE INVENTION
We have found that fluids containing the additive combinations of this invention, provide excellent antiwear, i.e., load carrying/extreme pressure characteristics. The antiwear characteristics of these fluids are not adversely impacted by optionally incorporating one or more friction modifiers.
While the invention is demonstrated for a particular power transmitting fluid, i.e., a CVT, it is contemplated that the antiwear and friction benefits of this invention are equally applicable to other types of power transmitting fluids such as automatic transmission fluids, gear oils, hydraulic fluids, heavy duty hydraulic fluids, industrial oils, power steering fluids, pump oils, tractor fluids, universal tractor fluids, and the like. These power transmitting fluids can be formulated with a variety of performance additives and in a variety of base oils.
Lubricating Oils
Lubricating oils useful in this invention are derived from natural lubricating oils, synthetic lubricating oils, and mixtures thereof. In general, both the natural and synthetic lubricating oil will each have a kinematic viscosity ranging from about 1 to about 40 mm
2
/s (cSt) at 100° C., although typical applications will require each oil to have a viscosity ranging from about 2 to about 8 mm
2
/s (cSt) at 100° C.
Natural lubricating oils include animal oils, vegetable oils (e.g., castor oil and lard oil), petroleum oils, mineral oils, and oils derived from coal or shale. The preferred natural lubricating oil is mineral oil.
Suitable mineral oils include all common mineral oil basestocks. This includes oils that are naphthenic or paraffinic in chemical structure. Oils that are refined by conventional methodology using acid, alkali, and clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents such as phenol, sulfur dioxide, furfural, dichlordiethyl ether, etc. They may be hydrotreated or hydrofined, dewaxed by chilling or catalytic dewaxing processes, or hydrocracked. The mineral oil may be produced from natural crude sources or be composed of isomerized wax materials or residues of other refining processes.
Typically the mineral oils will have kinematic viscosities of from 2.0 mm
2
/s (cSt) to 8.0 mm
2
/s (cSt) at 100° C. The preferred mineral oils have kinematic viscosities of from 2 to 6 mm
2
/s (cSt), and most preferred are those mineral oils with viscosities of 3 to 5 mm
2
/s (cSt) at 100° C.
Synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as oligomerized, polymerized, and interpolymerized olefins [e.g., polybutylenes, polypropylenes, propylene, isobutylene copolymers, chlorinated polylactenes, poly (1-hexenes), poly (1-octenes), poly-(1-decenes), etc., and mixtures thereof]; alkylbenzenes [e.g., dodecyl-benzenes, tetradecylbenzenes, dinonyl-benzenes, di(2-ethylhexyl)benzene, etc.]; polyphenyls [e.g., biphenyls, terphenyls, alkylated polyphenyls, etc.]; and alkylated diphenyl ethers, alkylated diphenyl sulfides, as well as their derivatives, analogs, and homologs thereof, and the like. The preferred oils from this class of synthetic oils are oligomers of &agr;-olefins, particularly oligomers of 1-decene.
Synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers, and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc. This class of synthetic oils is exemplified by: polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide; the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having an average molecular weight of 1000, diphenyl ether of polypropylene glycol having a molecular weight of 1000-1500) and mono- and poly-carboxylic esters thereof (e.g., the acetic aid esters, mixed C
3
-C
8
fatty acid esters, and C
12
oxo acid diester of tetraethylene glycol).
Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebasic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoethers, propylene glycol, etc.). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl isothalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebasic acid with two moles of tetraethylene glycol and two moles of 2-ethyl-hexanoic acid, and the like. A preferred type of oil from this class of synthetic oils are adipates of C
4
to C
12
alcohols.
Esters useful as synthetic lubricating oils also include those made from C
5
to C
12
monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane pentaerythritol, dipentaerythritol, tripentaerythritol, and the like.
Silicon-based oils (such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils) comprise another useful class of synthetic lubricating oils. These oils include tetra-ethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-2-ethylhexyl) silicate, tetra-(p-tert-butylphenyl) silicate, hexa-(4-methyl-2-pentoxy)-disiloxane, poly(methyl)-siloxanes and poly(methylphenyl) siloxanes, and the like. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, and diethyl ester of decylphosphonic acid ), polymeric tetra-hydrofurans, poly-&agr;-olefins, and the like.
The lubricating oils may be derived from refined, rerefined oils, or mixtures thereof. Unrefined oils are obtained directly from a natural source or synthetic source (e.g., coal, shale, or tar sands bitumen) without further purification or treatment. Examples of
Carter Neville J
Humphrey Robert Walter
Reeve Philip
Young Donald Glenn
Exxon Chemical Patents Inc
Medley Margaret
Toomer Cephia D.
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