FIELD OF INVENTION

[0001]. The present invention relates to a fluid lubricant particularly adapted for use as a lubricant in tractive drives. More particularly, the invention is related to a fluid formed from a mixture of an alpha-methyl styrene and a polyalphaolefin.

BACKGROUND OF INVENTION

[0002]. A conventional tractive drive or friction drive device is composed of at least two relatively rotatable members in a torque transmitting relationship. Torque (power) is transmitted from an input element to an output element through a nominal point or line contact, typically with a rolling action, by virtue of the traction from the proximal contact between the elements. The contact between the elements provides a means to transfer power from one source to a secondary element. Tractive drives can be used in automotive or industrial machinery to transmit power between rotating members. In particular, tractive drive devices are suited for use in transmissions and more particularly for continuous variable transmissions (CVT).

[0003]. Tractive drive elements are in proximal contact, but do not actually touch. It is generally known in the industry that a fluid film is provided between the elements. If the elements did contact, friction between the elements will generate heat and cause increased wear on the elements, leading to a degradation of the tractive drive. Lubricants are used to prevent the metal to metal contact and decrease the wear on the tractive elements. Thus, instead of metal to metal, or metal to rubber contact, a film of fluid is intermediate the contact points, The fluid functions to remove heat, prevent wear at the contact surface, lubricate the contacting elements and moving parts, and facilitate the transfer of torque. The fluid to a large extent determines the environment in which the tractive drive device

operates. In particular, the fluid reduces heat and friction, and functions to increase the traction coefficient of the tractive elements thereby increasing the transfer of power. [0004]. Desired characteristics for fluid lubricants that increase the performance of the tractive drive device are high shear resistance, low viscosity over a wide temperature range specifically at low temperatures, and good lubricating properties. High shear resistance is measured as the traction coefficient and is important for maximizing the power transmission between elements, A fluid with a high traction coefficient facilitates the maximum amount of torque between elements, resulting in minimal torque reduction due to slipping of the tractive drive. In addition, good lubricating characteristics ensure that heat is removed and that the contact surfaces are lubricated to minimize wear of the tractive device. [0005], Conventional fluid lubricants include naturally occurring oils of mineral origin, synthetic based lubricants, and combinations thereof, It is well known, however, that these fluids do not possess the characteristics, which enable them to perform satisfactorily in demanding applications, such as conditions that are typically associated with chain and belt CVT. Conventional fluid lubricants lack a high traction coefficient while still maintaining a low viscosity over a wide temperature range and in particular at low temperatures, such as - 4O ⁰ C. Traditionally, the fluid lubricant either functions with a high traction coefficient over a narrow temperature range, or the fluid lubricant is used over a wide temperature range, but with a low traction coefficient. To increase the performance of conventional fluid lubricants varying amounts of other materials are added to these fluids. As a result of the increased performance requirements imposed on these fluid lubricants it has become difficult to find additives which increase the performance properties of the fluid lubricant, but do not cause other problems, such as limiting the temperature range of operation, increased corrosion, or a lowered traction coefficient.

[0006]. Conventional fluid lubricants contain varying amounts of components that when in use will cause excessive foaming. Low foaming is desired in a fluid lubricant because minimal foaming ensures optimum coating of the traction gears To combat foaming of the fluid, defoamers are required in varying amounts typically between 5 ppm to 100 ppm (parts per million). The required defoamers decrease the effectiveness of conventional fluid lubricants because over time the defoamers lose the ability to decrease foaming Defoamers found in conventional fluid lubricants lose effectiveness due to settling, oxidation, or shearing, which cause the fluid lubricant to foam during use Additionally, conventional fluid lubπcants do not reduce the noise associated with traction gears. [0007]. It is therefore desirable to have a fluid for use in chain and belt CVT with properties such as: 1) a high coefficient of traction; 2) a low viscosity over a wide temperature range, 3) good phase stability at a low temperature, 4) noncorrosive to common materials of construction; 5) low foaming; 6) noise reduction; and, 7) good load beaπng and low wear rate properties.

SUMMARY OF INVENTION

[0008]. The present invention relates to a fluid lubricant for use in transmission of power The fluid lubricant is a liquid lubricant that includes a base fluid and performance additives. The base fluid includes a low-temperature control agent and a traction component The low- temperature control agent is preferably an oligomer or polymer of linear dimers of hydrogenated alphaolefins. The low-temperature control agent is included to ensure viscosity of the fluid lubricant remains low over a wide temperature range and in particular a low viscosity at temperatures of -40°C or less. The traction component is a hydrocarbon with non-aromatic cyclic moieties and preferably a linear dimer of alpha-methyl styrene. The traction component is particularly suited for use in fluid lubncants because of its high

traction coefficient. The performance additives are selected from the group consisting of friction modifiers, antioxidants, antiwear and extreme pressure additives, dispersants, metal deactivators, viscosity index improvers, defoamers, and mixtures thereof, in an amount sufficient to improve durability performance of the fluid lubricant.

[0009]. The present invention is formulated to produce a fluid lubricant that possesses a low viscosity over a wide temperature range, including temperatures at or below -4O ⁰ C, a high traction coefficient, increased noise reduction, decreased pressure, and low foaming. The above characteristics ensure that a fluid lubricant is formulated that will aide in peak performance of traction devices over diverse conditions. Specifically, the fluid's characteristics provide a fluid that will improve the performance of a belt or chain CVT by allowing the belt or chain CVT to operate with a high traction coefficient, over a wide temperature range.

[00010]. The present invention also relates to a method of using the fluid lubricant described above to lubricate power-transmitting apparatuses, such as chain or belt CVT. The fluid lubricant is used with a tractive drive device to increase torque transfer between the elements in a varying range of temperature environments under which tractive drive devices typically operate. Any amount of the fluid lubricant can be used with a tractive drive device so long as the device operates with a high traction coefficient over a wide temperature range. Preferably, the tractive device will function with a high traction coefficient at or below - 4O ⁰ C.

[00011], Further, the present invention relates to a method of using the fluid lubricant for numerous applications. Examples of potential uses include, but are not limited to, a canning lubricant, for high speed canning machines with gear systems operating at about

30,000 rpm, a wire rope lubricant for use in bridges and walkways, and as an elevator and lift lubricant,

DETAILED DESCRIPTION

[00012]. The present invention relates to a fluid lubricant and a method of using the lubricant. The fluid lubricant is particularly suited for use as a traction fluid. The fluid is composed of a base fluid and additional performance additives. The base fluid includes a mixture of a low-temperature viscosity control agent and a traction component, [00013]. One component of the base fluid is a low-temperature viscosity control agent, hereafter referred to as "control agent", The control agent is a viscosity reducer that operates to lower the viscosity of the fluid lubricant. Viscosity is the measurement of flow resistance due to internal friction within the fluid, and is measured in centistrokes (cSt). A lower cSt measurement means the fluid will flow with less resistance, because of minimal molecular friction within the fluid. The lower the viscosity the faster the fluid will flow. High viscosity substances are liquids that are thick and gelatinous in nature with slow flow. Low viscosity substances exhibit a fast flow with an example being water at room temperature, The control agent is a material that will flow at temperatures at or below -4O ⁰ C, and also will lower the viscosity, and increase the flow rate, of fluids to which it is added. The low viscosity of the control agent ensures that the fluid lubricant coats the tractive drive elements and remains flowable over a wide temperature range.

[00014]. The control agent of the present invention is a material, which possesses a viscosity that allows the control agent to flow over a varied temperature range. The control agent will have a viscosity of less than or equal to 7.2 cSt at 100° C. Preferably, the control agent is a material that possesses a viscosity of less than 6.0 cSt and more preferably 1,5 cSt to 2.5 cSt at 100 ⁰ C.

[00015]. Further, the control agent is a material that will retain mobility at low temperatures, such as -30 ⁰ C to -40 ⁰ C. The control agent is a material that when added in sufficient quantity will meet or exceed the viscosity requirements for Dexron® III and Mercon® V specifications at -40 ⁰ C. Both Dexron® III and Mercon® V specifications require a viscosity of less than or equal to 20,000 cP (centipoises) at -40°. (cP is a standard term used in the industry to define absolute viscosity for determining a fluids resistance to flow) Preferably, the control agent is a material that possesses a viscosity of less than 12,000 cP, and preferably between 250 cP and 2,500 cP at -40 ⁰ C.

[00016]. The control agent of the present invention includes either oligomers or polymers of linear alphaolefins. The linear alphaolefms contain between 10 and 60 carbon atoms, and preferably between 20 and 50 carbon atoms. Because the linear alphaolefin is preferably an "oligomer or polymer" it is a material with a low molecular weight. The linear alphaolefms possess a molecular weight range of between 200 and 1000. The molecular weight was estimated through carbon- number distribution using gas chromatography or following ASTM D-2878 standards. Preferably, the linear alphaolefins possess a molecular weight range between 250 and 650.

[00017]. Preferably, the linear alphaolefins are hydrogenated, and contain a minimal amount of carbon atoms that are not saturated. The hydrogenated material will be substantially free of carbons that are not saturated, or will include a minimal amount of unsaturated carbons that do not measurably or significantly affect the control agent's performance.

[00018]. Polymers and oligomers of linear alphaolefins are commercially available from manufactures, such as Exxon Mobil® and Chevron-Philips®. Examples of commercially available linear alphaolefins include PAO 2 (viscosity of 2 cSt at 100 ⁰ C),

PAO 4 (viscosity of 4 cSt at 10O ⁰ C), and PAO 6 (viscosity of 6cSt at 10O ⁰ C). The linear alphaolefins are produced in various viscosity grades, from 2 cSt to 100 cSt. Preferably, a viscosity grade of 8 cSt or lower is used with the current fluid lubricant. [00019]. Optionally, the control agent can be any material known in the industry for use in lowering the viscosity of a fluid. Examples include naphthenic mineral oils, esters such as diisodecyl adipate (DIDA) and diisodecyl phthlates (DIDP), polyalkylene glycols, and combinations thereof.

[00020]. The control agent is added in an amount equal to at least 50% by weight of the base fluid. Preferably, the control agent comprises between 60% to 95% by weight of the base fluid, and more preferably between 60% to 80% by weight of the base fluid. [00021]. The base fluid also contains a traction component. The traction component operates to increase the traction coefficient of the fluid. Preferably, the traction component is a hydrocarbon with non-aromatic moieties. It is particularly suited for use in a fluid lubricant because it possesses a high traction coefficient. A fluid with a high traction coefficient will ensure the optimum amount of torque (energy) is transferred between elements. Traction coefficient is defined as shearing resistance of a fluid while under high speed and load pressure. Typically, a fluid for use in a CVT chain or belt type design will have a coefficient of traction of greater than or equal to 0.05. CVT toroidal type designs require a coefficient of traction greater than or equal to 0.065. The hydrocarbon component functions to increase traction between the tractive drive elements and increase the transfer of torque. Preferably, the hydrocarbon is alpha-methyl styrene (AMS). More preferably, the AMS has been hydrogenated. The hydrogenated material will be substantially free of carbons that are not saturated, or will include a minimal amount of unsaturated carbons that do not measurably or significantly affect the component's performance. Further, the AMS

may include cyclic dimers of AMS, but preferably the component is composed of linear dimers of AMS. The preferred linear dimer of AMS is represented by the structure:

CH ₃ CH ₃ ,

CH ₃

[00022]. Optionally, the traction component can be any material known in the industry for use in increasing the traction coefficient in a fluid. The fluid optionally is an alkylated naphthalene that is produced by Exxon Mobil® and commercially available as Synesstic 12. [00023]. The traction component is added in an amount less than 50% by weight of the fluid lubricant. Preferably, the AMS component equals 5% to 40% by weight of the fluid lubricant and more preferably 20% to 40% by weight.

[00024). In addition to the base fluid, which includes a control agent and the traction component, the fluid lubricant contains an amount of performance additives. It is well known in the industry that performance additives are added to fluid lubricants to increase the performance of the fluid. The fluid lubricant includes friction modifiers, antioxidants, antiwear additives, extreme pressure additives, dispersants, metal deactivators, viscosity index improvers, defoamers, and combinations thereof. The performance additives are added to the fluid lubricant in an amount equal to between .01% and 20% by weight of the fluid lubricant. Preferably, the performance additives constitute between 5% and 15% by weight of the fluid lubricant.

[00025]. Optionally, the fluid lubricant will contain a friction modifier. Preferably, the friction modifier is a fatty acid ester, such as diisodecyl adipate. The diisodecyl adipate is produced by Exxon Mobil® and commercially known as Jayflex DIDA. The friction

modifier is preferably added in an amount between .01% and 2% by weight of the fluid lubricant.

[00026]. An antiwear additive can be included in the fluid lubricant. Preferably, the antiwear additive is phospho-thioate (TPPT), which is produced by Ciba® and commercially known as Irgalube TPPT. The antiwear additive is preferably added in an amount between .01% and 2% by weight of the fluid lubricant.

[00027]. Further, the fluid lubricant can contain antioxidants. Preferably, the antioxidents will be phenylalpha naphthal amine (PANA), which is commercially available through Ciba® and currently known as Irgalube Lo6. The antioxidants are preferably added in an amount between .01% and 1% by weight of the fluid lubricant.

[00028]. The optional component of a viscosity modifier or VI improver can be included in the fluid lubricant. Preferably, the viscosity modifier or VI improver is methacrylate polymers, which are commercially available and known as Rohmax 7-305 or an ethylene-propylene polymer such as CP-80 from Crompton Corporation. The viscosity modifier or VI improver is preferably added in an amount between .01% and 12% by weight of the fluid lubricant.

[00029]. The fluid lubricant can contain a pour point depressant. The pour point depressant is preferably an acrylic polymer that is produced and sold as the commercially available product Lubrizol 6662. The pour point depressant is preferably added in an amount between .01% and 1% by weight of the fluid lubricant.

[00030]. Further, the fluid lubricant can contain an over based dispersant. The over based dispersant is preferably calcium sulphonate and is preferably added in an amount between .01% and 5% by weight of the fluid lubricant.

[00031]. Optionally, a transmission fluid additive package containing all additives mentioned above can be used. Additive packages are commercially available from numerous sources including Lubrizol Corporation, as Lubrizol 3220T and Lubrizol 9636G, Infineium Corporation, and Afton Chemical. The additive packages are added to the base formulation in an amount sufficient to satisfy all requirements of the Dexron III specification. Preferably, the additive package is added in an amount between 5% to 15% by weight of the fluid lubricant. More preferably, the additive package is added in an amount between 5% to 10% by weight of the fluid lubricant.

[00032]. The mixture of the control agent, the traction component, and additional additives produce a fluid lubricant with characteristics specifically designed to endure the extreme conditions found in power transmitting apparatuses. The combination of the control agent and traction component produce a synergistic effect that when combined produce the present invention of a fluid lubricant with a low viscosity over a wide temperature range, and particularly low viscosity at -4O ⁰ C, while maintaining a high traction coefficient.

[00033]. The combination of the control agent and traction component produces a surprising result with regard to the traction coefficient. Combining the control agent and traction component results in a base fluid with a higher actual tested coefficient of traction compared to the expected calculated coefficient of traction. Because of the synergistic effect that results from the combination, a fluid lubricant with the desired high traction coefficient is produced.

[00034]. The present invention described above produces a fluid lubricant with low foaming characteristics. Low foaming fluids provide better lubrication because of the coating action of the fluid. Alternatively, fluids with higher foaming will possess air bubbles; the air

bubbles hinder coating since they are an intermediate between the fluid and the part. Foaming is defined as the formation of air bubbles above or within the fluid. Foaming is measured by injecting air into a fluid lubricant and determining the amount of air bubbles released or retained after a given time, Fluids that release the air bubbles quicker after injection are low foaming. Alternatively, fluids that retain the air bubbles are high foaming fluids, When compared to conventional fluid lubricants the present invention requires no defoamers or a minimal amount of defoamers to produce the fluid lubricant with non- foaming tendencies. Optionally, the fluid lubricant may contain a defoaming agent. Preferably, the defoaming agent is polymethyl siloxane and is preferably added in an amount between lppm to 5ρpm of the total fluid lubricant.

[00035]. Further, the present invention produces a fluid lubricant with increased noise reduction. When compared to conventional fluid lubricants the present invention reduces the noise levels in gear systems,

[00036]. The fluid lubricant of the present invention exhibits distinct characteristics that aid in the optimum performance of chain or belt CVT.

[00037]. Optionally, the present invention may be used in numerous other applications including traction devices that incoiporate the use of toroidal, cone, and planetrol type gears. The present fluid lubricant's use in the above traction gear systems will ensure increased torque transfer under varying conditions. Examples of machines that utilize the traction gear systems and can use the present fluid lubricant are high-speed machines used in food and pharmaceutical packaging and printing and lithographic equipment. The use of the present invention will aid in optimum performance of the machines using the traction gear systems. Further, the fluid lubricant of the present invention can also be used as a wire rope lubricant for use in bridges and walkways and as a lubricant for elevators and lifts.

EXAMPLES

[00038]. Samples were prepared with varying percentages of a control agent, a traction component, and performance additives and were analyzed to determine the physical properties of the fluid lubricant. Example 1.

[00039] . AMS and PAO 4 were blended together at a ratio of 20 : 80 by weight at ambient conditions to form the base fluid. Performance additives were then added to the base fluid and are as follows:

VI improver, Crompton Corp, CP80 at 2.00 Wt %

Friction Modifier, Exxon Mobil®, DIDA at 5.00 Wt %

Antioxidant, Ciba® LO6 at 0.75 Wt %

Antiwear agent, Ciba® TPPT at 1.25 Wt %

Antifoam agent, Ultra additives Foamban 130B at 0.1 Wt %

[00040]. The fluid lubricant prepared with the 20:80 ratio of AMS:PAO 4 was analyzed and the below data was collected.

Physical Properties

[00041]. The data above illustrates the characteristics of the present fluid lubricant. Numerous tests were conducted to illustrate the physical properties of the fluid lubricant.

1) The viscosity was determined following current ASTM-D445 standards used to determine viscosity. This method is conducted with a viscometer calibrated to determine the flow time measured in seconds. The kinematic viscosity is calculated by multiplying the viscometer calibration factor and seconds measured and is labeled as cSt.

2) The coefficient of traction was determined following standard industry tests. Particularly, the coefficient of fraction was determined through an MTM (Mini Traction Machine) and confirmed by a Twin-Disc Machine test.

3) The foaming properties of the fluid lubricant were evaluated based on the ASTM D- 892 test.

4) The four-ball wear test measures the scar diameter on stainless steel balls. The test is based on the standard ASTM D-2266 test. The test is conducted using four stainless steel balls, submerged in the test fluid; three balls at the bottom of the test cell and one on top of these three balls which rotates at a preset speed of 1200 rpm at 75 ⁰ C for 1 hour at the pre-selected load of 40 Kg. The balls are then measured for scar diameter with a microscope. The diameter measurement is calculated in millimeters. Low diameter means the lubricant provides better protection with good antiwear performance, larger diameter such as 1.00 mm or over signifies poor antiwear performance.

5) The evaporation loss test was conducted according to the standard ASTM D-972 test. The evaporation cell is filled with an amount of test fluid and weighed. Next the evaporation cell is placed in a bath preset at the desired temperature for 24 hours. At

the end of the 24-hour time period the test cell is removed, allowed to cool, and weighed. The difference in weight is then calculated.

6) The oxidation stability test was conducted according to Federal Test method 3008. Metal coupons such as steel, copper, aluminum, silver, and magnesium are submerged with the test fluid in a cylinder and heated to 17O ⁰ C for 192 hours. The oil viscosity and acid number is determined after the test and reported as percent change.

7) The copper corrosion test is conducted according to the standard ASTM D130 test. A copper coupon is placed in a test cell that is half filled with the test fluid until it covers the copper coupon. The test cell is next heated for 24 hours at 100 ⁰ C. The color change of the copper coupon is then recorded based on a color comparator.

Example 2.

[00042]. AMS and PAO 4 were blended together at a ratio of 40:60 by weight at ambient conditions to from the base fluid. The performance additives as described in example 1 were then added to the base fluid.

[00043]. The fluid lubricant prepared with the 40:60 ratio of AMS:PAO 4 was analyzed and the below data was collected.

Physical Properties

Example 3.

[00044] . Alkylated Naphthalene and PAO 4 were blended together at a ratio of 40 : 60 by weight at ambient conditions to from the base fluid. The performance additives as described in example 1 were then added to the base fluid.

[00045]. The fluid lubricant prepared with the 40:60 ratio of Alkylated

Naphthalen:PAO 4 was analyzed and the below data was collected.

Physical Properties

Example 4.

[00046], Fluid lubricants were tested with varying amounts of AMS;PAO ratios by weight at ambient conditions. The fluid lubricants were tested to determine the actual coefficient of traction versus the calculated coefficient of traction. The AMS and PAO constituents were combined in a beaker and mixed with a magnetic stir rod until the fluid lubricant mixture was created. The fluid lubricants prepared with the varying ratios of 20:80, 30:70, and 40:60 were analyzed and the below data was collected.

Actual 0.095 0.020 0.052 0.060 0.075

[00047]. The data above illustrates the synergistic relationship discovered between the

AMS and PAO components. The AMS and PAL when combined to produce the fluid base have a synergistic effect on the fluid lubricant mixture. The synergistic effect causes the fluid lubricant to possess a coefficient of traction that is higher than calculated. The coefficient of traction was determined following industry standards using an MTM test and confirmed by a Twin-Disc Machine test. The data illustrates that the tested coefficient of traction is higher when compared to the pre-calculated coefficient of traction expected for each ratio. Because of the synergistic effect the fluid lubricant of the present invention has a high coefficient of traction and will aide in the transfer of torque in traction gear systems. Example 5.

[00048], A noise level comparison was evaluated between the present invention fluid lubricant and conventional mineral oil base fluid lubricants such as Chevron ATF. The test evaluated the reduction of noise levels of the present fluid lubricant versus the mineral oil through the use of a Twin-Disc Machine, which was run at 300 psi and 500 psi while the noise levels were recorded with a digital sound level meter. The noise levels of mineral oil averaged 109 dB at 500 psi and 107 dB at 300 psi. Comparatively, the present fluid lubricant produced noise levels of 105 dB at 500 psi and 102 dB at 300 psi. Based on the above data the present fluid lubricant reduces the noise level typically encountered in traction gear systems. Example 6.

[00049]. Foaming characteristics were compared between the present fluid lubricant and conventional mineral oil base fluid lubricants. Equal amounts of the present fluid

lubricant and conventional mineral oil base lubricant were compared for foaming characteristics based on a standard ASTM D-892 test. The foaming test is conducted on a 200-ml test sample of the fluid placed in a lOOO-ml cylinder. A measured amount of 475 ml of air is then injected into the sample through a porous stone attached to a tube and an airflow meter in five minutes. The foam height is then measured in the fluid. The initial test when conducted at room temperature is called sequence 1, sequence II is the test conducted at 98 ⁰ C. The same fluid is then re-tested at room temperature following the same procedure to produce sequence III. Both fluid lubricants were then oxidized at 170 ⁰ C for 48 hours and re- tested according to the ASTM D-892 test. Foaming measured at a rate of less than 10 ml for the present fluid lubricant formulation. Comparatively, the conventional mineral oil produced a foaming result of 75 ml. Based on the above data the present fluid lubricant exhibits decreased foaming characteristics when compared to conventional mineral oil lubricants.

[00050]. Thus, there has been shown and described a fluid lubricant and method for its use that fulfills all objects and advantages sought therefore. The invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. It is apparent to those skilled in the art, however, that many changes, variations, modification, other uses, and applications to the fluid lubricant are possible, and also such changes, variations, modifications, other uses, and application which do not depart from the sprit and scope of the invention are deemed to be covered by the invention, which is limited only by the claims which follow.