Patent Application
20120270693
The present invention relates to a lubricating oil, more particularly to a lubricating oil applied to between a pair of slidable friction members to improve sliding characteristics of the friction members. The present invention further relates to a friction member where the lubricating oil is used, and a gear-type differential with a differential limiting function.
Conventionally, noise and vibration (NV) of a vehicle are caused by a self-excited vibration (may be called stick-slip phenomenon) generated in the event that a vibration system operable by interactions among inertial force, restoring force, and frictional force is destabilized on sliding surfaces. The vibration system loses stability when a coefficient of friction lowers as a sliding velocity increases or during transition from a high static friction to a low dynamic friction, resulting in the occurrence of stick-slip phenomenon.
A necessary and sufficient condition for avoiding the occurrence of stick-slip phenomenon is to obtain tribological properties where the coefficient of friction is elevated as the sliding velocity increases. The μ-ν characteristics with positive gradient can attenuate the generated stick-slip phenomenon sooner.
Some of differential limiting devices conventionally available for vehicles are torque-responsive devices adapted to limit a differential depending on a torque reaction force generated in a drive system. A torque-responsive differential limiting device is conventionally provided with a ring gear and a sun gear coaxially disposed, planetary gears to be meshed with these gears, and a planetary carrier supporting the planetary gears while slidably contacting top lands thereof so that the planetary gears are orbitally revolvable and rotatable on their own rotational axes. The differential limiting device is adapted to allow a differential between two outputs based on the rotation and orbital revolution of the planetary gears and also limit the differential based on a thrusting force resulting from a rotational reaction force generated between the gears meshed with each other and a frictional force between slidably contacting surfaces (top lands and planetary carrier-side sliding surfaces of the planetary gears).
In any differential limiting devices where the top land of the planetary gears slidably contact the planetary carrier, it is very important that a lubricating oil applied to between sliding surfaces has good anti-vibration and durability. A deterioration of the lubricating oil supplied to between the sliding surfaces may involve unfavorable events such as vibration increase, noise occurrence, excessive abrasion on sliding surfaces, and seizure.
The vehicles available in the market in recent years need to fulfill more advanced noise reduction than conventionally demanded according to a hybrid car and reduction in weight for achieving low-fuel consumption, and differential limiting devices loaded therein should also need to fulfill the same requirement. It is an important task in differential limiting devices to maximize the anti-vibration of the lubricating oil (better lubricity) for further noise reduction.
So far were developed some lubricating oils used in shock absorbers, examples of which are disclosed in JP Publication No. 2003-147379 and JP Publication No. 2008-133332. However, lubricating oils used in gear-type differential limiting devices have been mostly developed with a large stress on extreme-pressure proofness because of such a high contact pressure as several hundred MPa during use which is a distinct feature of any gear-type devices, and it has been hardly discussed or studied to use a friction modifier (FM) in sliding portions in consideration of better anti-vibration.
The present invention was accomplished to solve these conventional technical problems. The present invention provides a lubricating oil used in a differential limiting device which ensures a remarkable quietness (μ-ν characteristics with positive gradient) between sliding portions of the friction members and a differential limiting device (differential with a differential limiting function).
To solve the conventional technical problems, the inventors of the present invention carried out various studies on additives to be added to lubricating oils used in a friction-type driving force transmission apparatus and finally accomplished the present invention.
A lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus, the lubricating oil including: at least one of two additives; a first additive selected from an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (Chemical Formula 2); and a second additive selected from a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (Chemical Formula 4).
R1—NH2 [Chemical formula 1]
1≦x+y≦3
The lubricating oil according to the present invention has a specific peak in a 31P-nuclear magnetic resonance analysis.
A friction member and a differential with a differential limiting function according to the present invention are characterized in that a lubricating oil is applied thereto, the lubricating oil including at least one of the two additives or a lubricating oil including a thiophosphate diester and/or an amine salt thereof by a specific proportion, that is the lubricating oil according to the present invention. The friction member according to the present invention is applicable to the differential with a differential limiting function according to the present invention.
A first lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus. The lubricating oil includes at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2).
Given that the mass of the lubricating oil is 100%, at least one of the aliphatic amine, the aliphatic amine ethylene oxide adduct, and the aliphatic amine and the aliphatic amine ethylene oxide adduct in total is preferably included by 1.0 to 5.0%.
The saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 of the aliphatic amine, the aliphatic amine ethylene oxide adduct is preferably an unsaturated hydrocarbon group with a carbon number of 18.
Given that the mass of the lubricating oil is 100%, at least one of an acidic phosphate ester and an acidic thiophosphate ester is preferably included so that a phosphorus content stays in a range of 0.20%≦P≦0.50%.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included in a state where the aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 and an amine salt thereof are formed.
The lubricating oil preferably includes a hydrocarbon oil as a base oil thereof, wherein a peak absorbency of the lubricating oil at infrared spectral wave numbers of 1,740±20 cm−1 is at most 1.5 in an infrared spectroscopic analysis using a fixed cell for liquid having an optical length of 0.05 mm±0.005 mm.
The lubricating oil preferably exhibits a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis.
Given that the mass of the lubricating oil is 100%, a phosphorus content derived from a thiophosphate diester and/or an amine salt thereof is preferably 0.010% or more.
A second lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus. The lubricating oil includes at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
Given that the mass of the lubricating oil is 100%, at least one of the phosphorous acid monoester, the phosphorous acid diester, and the phosphorous acid monoester and the phosphorous acid diester in total is preferably included by 1.0% to 5.0%.
The saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 of the phosphorous acid monoester, the phosphorous acid diester is preferably an unsaturated hydrocarbon group with a carbon number of 18.
Given that the mass of the lubricating oil is 100%, at least one of an acidic phosphate ester and an acidic thiophosphate ester is preferably included so that aphosphorus content stays in a range of 0.20%≦P≦0.50%.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included in a state where the aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 and an amine salt thereof are formed.
The lubricating oil preferably includes a hydrocarbon oil as a base oil thereof, wherein a peak absorbency of the lubricating oil at infrared spectral wave numbers of 1,740±20 cm−1 is at most 1.5 in an infrared spectroscopic analysis using a fixed cell for liquid having an optical length of 0.05 mm±0.005 mm.
The lubricating oil preferably exhibits a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis.
Given that the mass of the lubricating oil is 100%, a phosphorus content derived from a thiophosphate diester and/or an amine salt thereof is preferably 0.010% or more.
A third lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus, the lubricating oil including: at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2); and at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
Given that the mass of the lubricating oil is 100%, at least one of the aliphatic amine, the aliphatic amine ethylene oxide adduct, and the aliphatic amine and the aliphatic amine ethylene oxide adduct in total is preferably included by 1.0% to 5.0%, and at least one of the phosphorous acid monoester, the phosphorous acid diester, and the phosphorous acid monoester and the phosphorous acid diester in total is preferably included by 1.0% to 5.0%.
Given that the mass of the lubricating oil is 100%, at least one of an acidic phosphate ester and an acidic thiophosphate ester is preferably included so that a phosphorus content stays in a range of 0.20%≦P≦0.50%.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included in a state where the aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 and an amine salt thereof are formed.
The lubricating oil preferably includes a hydrocarbon oil as a base oil thereof, wherein a peak absorbency of the lubricating oil at infrared spectral wave numbers of 1,740±20 cm−1 is at most 1.5 in an infrared spectroscopic analysis using a fixed cell for liquid having an optical length of 0.05 mm±0.005 mm.
The lubricating oil preferably exhibits a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis.
Given that the mass of the lubricating oil is 100%, a phosphorus content derived from a thiophosphate diester and/or an amine salt thereof is preferably 0.010% or more.
A fourth lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus, the lubricating oil including: an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1); and at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
The phosphorous acid diester and/or the phosphorous acid monoester is preferably included in a state where the aliphatic amine and an amine salt thereof are formed.
A fifth lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus, wherein the lubricating oil exhibits a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis.
Given that the mass of the lubricating oil is 100%, a phosphorus content derived from the thiophosphate diester and/or the amine salt thereof is preferably 0.010% or more.
Given that the mass of the lubricating oil is 100%, at least one of an acidic phosphate ester and an acidic thiophosphate ester is preferably included so that a phosphorus content stays in a range of 0.20%≦P≦0.50%.
The lubricating oil preferably includes a hydrocarbon oil as a base oil thereof, wherein a peak absorbency of the lubricating oil at infrared spectral wave numbers of 1,740±20 cm−1 is at most 1.5 in an infrared spectroscopic analysis using a fixed cell for liquid having an optical length of 0.05 mm±0.005 mm.
A first friction member according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2).
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a diamond-like carbon film formed thereon.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a tungsten carbide/diamond-like carbon film formed thereon, and a sliding surface of the other friction member is preferably nitrided.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members is preferably made from an iron-based metal, and a sliding surface of the other friction member is preferably nitrided.
A second friction member according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a diamond-like carbon film formed thereon.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a tungsten carbide/diamond-like carbon film formed thereon, and a sliding surface of the other friction member is preferably nitrided.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members is preferably made from an iron-based metal, and a sliding surface of the other friction member is preferably nitrided.
A third friction member according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including: at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2); and at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a diamond-like carbon film formed thereon.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a tungsten carbide/diamond-like carbon film formed thereon, and a sliding surface of the other friction member is preferably nitrided.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members is preferably made from an iron-based metal, and a sliding surface of the other friction member is preferably nitrided.
A fourth friction member according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil exhibiting a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a diamond-like carbon film formed thereon.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a tungsten carbide/diamond-like carbon film formed thereon, and a sliding surface of the other friction member is preferably nitrided.
Of a pair of friction members sliding with each other, a sliding surface of one of the friction members is preferably made from an iron-based metal, and a sliding surface of the other friction member is preferably nitrided.
A first gear-type differential with a differential limiting function according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2).
The first gear-type differential with a differential limiting function is preferably a driving force transmission apparatus, the apparatus including: a plurality of planetary gears; a planetary carrier for supporting the plurality of planetary gears so that the plurality of planetary gears are orbitally revolvable and rotatable on their own rotational axes; and a pair of gears disposed coaxial with the planetary carrier and differentially rotatable via the planetary gears, wherein the lubricating oil is applied to between sliding surfaces of the planetary gears and the planetary carrier.
A second gear-type differential with a differential limiting function according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
The second gear-type differential with a differential limiting function is preferably a driving force transmission apparatus, the apparatus including: a plurality of planetary gears; a planetary carrier for supporting the plurality of planetary gears so that the plurality of planetary gears are orbitally revolvable and rotatable on their own rotational axes; and a pair of gears disposed coaxial with the planetary carrier and differentially rotatable via the planetary gears, wherein the lubricating oil is applied to between sliding surfaces of the planetary gears and the planetary carrier.
A third gear-type differential with a differential limiting function according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including: at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2); and at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
The third gear-type differential with a differential limiting function is preferably a driving force transmission apparatus, including: a plurality of planetary gears; a planetary carrier for supporting the plurality of planetary gears so that the plurality of planetary gears are orbitally revolvable and rotatable on their own rotational axes; and a pair of gears disposed coaxial with the planetary carrier and differentially rotatable via the planetary gears, wherein the lubricating oil is applied to between sliding surfaces of the planetary gears and the planetary carrier.
A fourth gear-type differential with a differential limiting function according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, wherein, given that the mass of the lubricating oil is 100%, a phosphorus content derived from a thiophosphate diester (Chemical Formula 5) and/or an amine salt thereof (Chemical Formula 6) is preferably 0.010% or more.
The gear-type differential with a differential limiting function is preferably a driving force transmission apparatus, the apparatus including: a plurality of planetary gears; a planetary carrier for supporting the plurality of planetary gears so that the plurality of planetary gears are orbitally revolvable and rotatable on their own rotational axes; and a pair of gears disposed coaxial with the planetary carrier and differentially rotatable via the planetary gears, wherein the lubricating oil is applied to between sliding surfaces of the planetary gears and the planetary carrier.
The lubricating oil according to the present invention, when mixed with the specific additives, succeeds in improving the μ-ν characteristics toward positive gradient. As a result, the friction member and the gear-type differential with a differential limiting function (friction-type differential limiting device) wherein the lubricating oil according to the present invention is used, can both ensure remarkable quietness.
A lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus, the lubricating oil including at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2).
When the aliphatic amine expressed by Chemical Formula 1 and the aliphatic amine ethylene oxide adduct expressed by Chemical Formula 2 are included in the lubricating oil according to the present invention, μ-ν characteristics with positive gradient are obtained when used in the friction-type differential limiting device. More specifically, the lubricating oil including these additives, when applied to a friction surface of the friction-type differential limiting device, is thought to prevent solid contact thereon.
In the case where the saturated or unsaturated hydrocarbon groups (hydrocarbon groups expressed by R1 and R2 in Chemical Formulas 1 and 2) of the aliphatic amine and the aliphatic amine ethylene oxide adduct have a carbon number of 11 or less, it fails to ensure an enough adsorption film thickness effective for preventing the solid contact. The hydrocarbon group with a carbon number of 21 or more results in a lower polarity, leading to a less adsorptivity on the friction surface.
As is known from Chemical Formula 2, an amount of the aliphatic amine ethylene oxide adduct (x+y) stays in the range of 1 to 3. The amount to be added larger than 3 overly increases the polarity, undermining the solubility in the base oil. As a result, the ethylene oxide is likely to separate out from the lubricating oil.
Given that the mass of the lubricating oil according to the present invention is 100%, at least one of the aliphatic amine, the aliphatic amine ethylene oxide adduct, and the aliphatic amine and the aliphatic amine ethylene oxide adduct in total is preferably included by 1.0% to 5.0%. As far as the content of the aliphatic amine and/or the aliphatic amine ethylene oxide adduct is 1.0% to 5.0% by mass, μ-ν characteristics can be more effectively improved toward positive gradient in the friction-type differential limiting device where the lubricating oil is used.
The content of the aliphatic amine and/or the aliphatic amine ethylene oxide adduct less than 1.0% by mass fails to attain an expected durability and desirable μ-ν characteristics. The additive content more than 5.0% by mass leads to excess formation of the adsorption film, causing chemical wear or inviting deposition of the additive ingredients from the lubricating oil. Therefore, the additive content is more preferably 1.5% to 4.0% by mass.
The saturated or unsaturated hydrocarbon group of the aliphatic amine, the aliphatic amine ethylene oxide adduct with a carbon number of 12 to 20 is preferably an unsaturated hydrocarbon group with a carbon number of 18. In the lubricating oil according to the present invention, the hydrocarbon group of the additive added thereto as FM may be a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20, however, the hydrocarbon group is preferably an unsaturated hydrocarbon group with a carbon number of 18 because an effect obtained by the additive is thereby improved, and the unsaturated hydrocarbon group allows a larger volume of additive to be dissolved in the lubricating oil, providing a better durability. The saturated hydrocarbon group is preferably an alkenyl group, and the unsaturated hydrocarbon group with a carbon number of 18 is preferably an oleyl group.
Given that the mass of the lubricating oil according to the present invention is 100%, at least one of an acidic phosphate ester and an acidic thiophosphate ester is preferably included so that a phosphorus content stays in a range of 0.20%≦P≦0.50%.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included because, when used in a differential gear of the friction-type differential limiting device, wear and seizure of the gear are prevented from happening.
The phosphorus content below 0.20% by mass fails to ensure an enough wear resistance and seizure proofness. The phosphorus content larger than 0.50% by mass causes an excessive reaction of an extreme pressure agent, resulting in the occurrence of chemical wear or corrosion damage. The phosphorus content is more desirably 0.20% to 0.40% by mass.
The acidic phosphate ester and the acidic thiophosphate ester may be a monoester, diester, and triester, or a mixture of these esters.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included in a state where the aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 and an amine salt thereof are formed. At least one of the acidic phosphate ester and the acidic thiophosphate ester forms an amine salt, thereby more effectively improving μ-ν characteristics toward positive gradient while preventing wear and seizure of the gear. The aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 wherein at least one of the acidic phosphate ester and the acidic thiophosphate ester forms an amine salt is preferably the aliphatic amine expressed by Chemical Formula 1.
To form the aliphatic amine and the amine salt, at least one of an acidic phosphate ester or an acidic thiophosphate ester having an OH group is preferably included as a phosphorus content of the extreme pressure additive.
Similarly to any conventional lubricating oils, the lubricating oil according to the present invention may include a base oil and an additive mixed with the base oil.
The lubricating oil according to the present invention preferably includes a hydrocarbon oil as a base oil thereof, wherein a peak absorbency of the lubricating oil at infrared spectral wave numbers of 1,740±20 cm−1 is at most 1.5 in an infrared spectroscopic analysis using a fixed cell for liquid having an optical length of 0.05 mm±0.005 mm.
The base oil is preferably a non-ester base oil (hydrocarbon oil). As an ester content of the base oil increases, the additive (FM) having a polar group is less adsorbed, meaning that the base oil preferably includes as little ester component as possible. The peak at the infrared spectral wave numbers of 1,740±20 cm−1 in the infrared spectroscopic analysis (FT-IR) indicates a peak of the ester content. Therefore, the base oil includes less ester as the peak absorbency in 1,740±20 cm−1 is smaller in the lubricating oil FT-IR.
The lubricating oil according to the present invention preferably exhibits a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis. In the 31P-nuclear magnetic resonance analysis (NMR), a peak assigned to the thiophosphate diester is detected at near 57 ppm, meaning that the lubricating oil exhibiting a peak of 57±2 ppm in NMR includes the thiophosphate diester. The lubricating oil including the thiophosphate diester can more effectively attain μ-ν characteristics with positive gradient while preventing wear and seizure of the gear in the friction-type driving force transmission apparatus. When the peak of 57±2 ppm is exhibited in NMR, μ-ν characteristics can be effectively improved toward positive gradient, while wear and seizure of the gear are prevented from happening.
Given that the mass of the lubricating oil is 100%, a phosphorus content associated with a thiophosphate diester and/or an amine salt thereof is preferably more than 0.010%. The phosphorus content less than 0.010% is too small to fully exert an expected effect of the additive. The thiophosphate diester is preferably a compound expressed by expressed by Chemical Formula 5, and the amine salt thereof is preferably a compound expressed by expressed by Chemical Formula 6.
A lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus. The lubricating oil includes at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 where R4 of Chemical Formula 3 is hydrogen (expressed by Chemical Formula 4).
The phosphorous acid diester and the phosphorous acid monoester included in the lubricating oil according to the present invention serves a purpose similarly to that of aliphatic amine and/or the aliphatic amine ethylene oxide adduct according to the expressed by first invention and exerts an effect similar to that of the first invention. The phosphorous acid diester and/or the phosphorous acid monoester, when included in the lubricating oil, favorably attain μ-ν characteristics with positive gradient in the friction-type differential limiting device. More specifically, the lubricating oil including these additives, when applied to a friction surface of the friction-type differential limiting device, is thought to prevent solid contact thereon.
In the case where the saturated or unsaturated hydrocarbon groups with a carbon number of 12 to 20 (hydrocarbon groups expressed by R3 and R4 in expressed by Chemical Formula 3) of the phosphorous acid diester and the saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (hydrocarbon group expressed by R5 in expressed by Chemical Formula 4) of the phosphorous acid monoester respectively have a carbon number of 11 or less, it fails to ensure an enough adsorption film thickness effective for preventing the solid contact. The hydrocarbon group with a carbon number 21 or more results in a lower polarity, leading to a less adsorptivity on the friction surface.
Given that the mass of the lubricating oil according to the present invention is 100%, at least one of the phosphorous acid monoester, the phosphorous acid diester, and the phosphorous acid monoester and the phosphorous acid diester in total is preferably included by 1.0% to 5.0%. As far as a content of the phosphorous acid monoester and/or the phosphorous acid diester stays in the range of 1.0% to 5.0% by mass, μ-ν characteristics can be more effectively improved toward positive gradient in the friction-type differential limiting device where the lubricating oil is used.
The content of the phosphorous acid monoester and/or the phosphorous acid diester less than 1.0% by mass fails to attain an expected durability and desirable μ-ν characteristics. The additive content more than 5.0% by mass leads to excess formation of the adsorption film, causing chemical wear or inviting deposition of the additive ingredients from the lubricating oil. The additive content is more desirably 1.5% to 4.0% by mass.
The saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 of the phosphorous acid monoester, the phosphorous acid diester is preferably an unsaturated hydrocarbon group with a carbon number of 18. In the lubricating oil according to the present invention, the hydrocarbon group of the additive added thereto as FM may be a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20, however, the hydrocarbon group is preferably an unsaturated hydrocarbon group with a carbon number of 18 because an effect obtained by the additive is thereby improved, and the unsaturated hydrocarbon group allows a large volume of additive to be dissolved in the lubricating oil, providing a better durability. The saturated hydrocarbon group is preferably an alkenyl group, and the unsaturated hydrocarbon group with a carbon number of 18 is preferably an oleyl group.
Given that the mass of the lubricating oil is 100%, at least one of an acidic phosphate ester and an acidic thiophosphate ester is preferably included so that a phosphorus content stays in a range of 0.20%≦P≦0.50%.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included because, when used in a differential gear of the friction-type differential limiting device, wear and seizure of the gear are prevented from happening.
The phosphorus content below 0.20% by mass fails to ensure an enough wear resistance and seizure proofness. The phosphorus content larger than 0.50% by mass causes an excessive reaction of an extreme pressure agent, resulting in the occurrence of chemical wear or corrosion damage. The phosphorus content is more desirably 0.20% to 0.40% by mass.
The acidic phosphate ester and the acidic thiophosphate ester may be a monoester, diester, and triester, or a mixture of these esters.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included in a state where the aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 and an amine salt thereof are formed. At least one of the acidic phosphate ester and the acidic thiophosphate ester forms an amine salt, thereby more effectively improving μ-ν characteristics toward positive gradient while preventing wear and seizure of the gear.
To form the aliphatic amine and the amine salt, at least one of an acidic phosphate ester or an acidic thiophosphate ester having an OH group is preferably included as a phosphorus content of the extreme-pressure agent.
Similarly to any conventional lubricating oils, the lubricating oil according to the present invention may include a base oil and an additive mixed with the base oil.
The lubricating oil according to the present invention preferably includes a hydrocarbon oil as a base oil thereof, wherein a peak absorbency of the lubricating oil at infrared spectral wave numbers of 1,740±20 cm−1 is at most 1.5 in an infrared spectroscopic analysis using a fixed cell for liquid having an optical length of 0.05 mm±0.005 mm.
The base oil is preferably a non-ester base oil (hydrocarbon oil). As an ester content in the base oil increases, the additive (FM) having a polar group is less adsorbed, meaning that the base oil preferably includes as little ester component as possible. The peak at the infrared spectral wave numbers of 1,740±20 cm−1 in the infrared spectroscopic analysis (FT-IR) indicates a peak of the ester content. Therefore, the base oil includes less ester as the peak absorbency at 1,740±20 cm−1 is smaller in the lubricating oil FT-IR.
The lubricating oil according to the present invention preferably exhibits a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis. In the 31P-nuclear magnetic resonance analysis (NMR), a peak assigned to the thiophosphate diester is detected at near 57 ppm, meaning that the lubricating oil exhibiting a peak of 57±2 ppm in NMR includes the thiophosphate diester. The lubricating oil including the thiophosphate diester can more effectively improve μ-ν characteristics toward positive gradient while preventing wear and seizure of the gear in the friction-type driving force transmission apparatus. When the peak of 57±2 ppm is exhibited in NMR, μ-ν characteristics can be effectively improved toward positive gradient, while wear and seizure of the gear are prevented from happening.
Given that the mass of the lubricating oil is 100%, a phosphorus content associated with the thiophosphate diester and/or the thiophosphate diester amine salt is preferably 0.010% or more. The phosphorus content less than 0.010% is too small to fully exert an effect of the additive. The thiophosphate diester is preferably a compound expressed by Chemical Formula 5, and the amine salt of the thiophosphate diester is preferably a compound expressed by Chemical Formula 6.
A third lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus, the lubricating oil including: at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2); and at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 where R4 of expressed by Chemical Formula 3 is hydrogen (expressed by Chemical Formula 4).
The lubricating oil according to the present invention includes both of the additives respectively mixed with the first lubricating oil and the second lubricating oil, thereby exerting the effects according to these inventions at once. When the aliphatic amine and/or the aliphatic amine ethylene oxide adduct and the phosphorous acid diester and/or phosphorous acid monoester are included in the lubricating oil according to the present invention, μ-ν characteristics with positive gradient are favorably attained in the friction-type differential limiting device. More specifically, the lubricating oil including these additives, when applied to a friction surface of the friction-type differential limiting device, is thought to prevent solid contact thereon.
In the case where the saturated or unsaturated hydrocarbon groups (hydrocarbon groups expressed by R1 and R2 in Chemical Formulas 1 and 2) of the aliphatic amine and the aliphatic amine ethylene oxide adduct have a carbon number of 11 or less, it fails to ensure an enough adsorption film thickness effective for preventing the solid contact. The hydrocarbon group with a carbon number of 21 or more results in a lower polarity, leading to a less adsorptivity on the friction surface.
As is known from Chemical Formula 2, an amount of the aliphatic amine ethylene oxide adduct (x+y) stays in the range of 1 to 3. The amount to be added larger than 3 overly increases the polarity, undermining the solubility in the base oil. Asa result, the ethylene oxide is likely to separate out from the lubricating oil.
In the case where the saturated or unsaturated hydrocarbon groups with a carbon number of 12 to 20 (hydrocarbon groups expressed by R3 and R4 in Chemical Formula 3) of the phosphorous acid diester and the saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (hydrocarbon group expressed by R4 in Chemical Formula 4) of the phosphorous acid monoester respectively have a carbon number of 11 or less, it fails to ensure an enough adsorption film thickness effective for preventing the solid contact. The hydrocarbon group with a carbon number of 21 or more results in a lower polarity, leading to a less adsorptivity on the friction surface.
Given that the mass of the lubricating oil is 100%, at least one of the aliphatic amine, the aliphatic amine ethylene oxide adduct, and the aliphatic amine and the aliphatic amine ethylene oxide adduct in total is preferably included by 1.0% to 5.0%, and at least one of the phosphorous acid monoester, the phosphorous acid diester, and the phosphorous acid monoester and the phosphorous acid diester in total is preferably included by 1.0% to 5.0%. When the content of the aliphatic amine and/or the aliphatic amine ethylene oxide adduct is 1.0% to 5.0% by mass, and the content of the phosphorous acid diester and/or the phosphorous acid monoester is 1.0% to 5.0% by mass, the μ-ν characteristics are more effectively improved toward positive gradient in the friction-type differential limiting device where the lubricating oil is used.
In the case where the additive content of the aliphatic amine and/or the aliphatic amine ethylene oxide adduct and the additive content of the phosphorous acid diester and/or the phosphorous acid monoester are less than 1.0% by mass, not only durability but also desirable μ-ν characteristics are undermined. The additive content more than 5.0% by mass leads to excess formation of the adsorption film, causing chemical wear or inviting deposition of the additive ingredients from the lubricating oil. Therefore, the content of the aliphatic amine and/or the aliphatic amine ethylene oxide adduct and the content of the phosphorous acid diester and/or the phosphorous acid monoester are more desirably 1.5% to 4.0% by mass.
The saturated or unsaturated hydrocarbon group of the phosphorous acid diester, the phosphorous acid monoester with a carbon number of 12 to 20 is preferably an unsaturated hydrocarbon group with a carbon number of 18. In the lubricating oil according to the present invention, the hydrocarbon group of the additive added thereto as FM may be a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20, however, the hydrocarbon group is preferably an unsaturated hydrocarbon group with a carbon number of 18 because an effect obtained by the additive is thereby improved, and the unsaturated hydrocarbon group allows a large volume of additive to be dissolved in the lubricating oil, providing a better durability. The saturated hydrocarbon group is preferably an alkenyl group, and the unsaturated hydrocarbon group with a carbon number of 18 is preferably an oleyl group.
Given that the mass of the lubricating oil according to the present invention is 100%, at least one of an acidic phosphate ester and an acidic thiophosphate ester is preferably included so that a phosphorus content stays in a range of 0.20%≦P≦0.50%.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included because, when used in a differential gear of the friction-type differential limiting device, wear and seizure of the gear are prevented from happening.
The phosphorus content below 0.20% by mass fails to ensure an enough wear resistance and seizure proofness. The phosphorus content larger than 0.50% by mass causes an excessive reaction of an extreme pressure agent, resulting in the occurrence of chemical wear or corrosion damage. The phosphorus content is more desirably 0.20% to 0.40% by mass.
The acidic phosphate ester and the acidic thiophosphate ester may be a monoester, diester, and triester, or a mixture of these esters.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included in a state where the aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 and an amine salt thereof are formed. At least one of the acidic phosphate ester and the acidic thiophosphate ester forms an amine salt, thereby more effectively improving μ-ν characteristics toward positive gradient while preventing wear and seizure of the gear. The aliphatic amine having the saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 wherein at least one of the acidic phosphate ester and the acidic thiophosphate ester forms an amine salt is preferably the aliphatic amine expressed by expressed by Chemical Formula 22.
To form the aliphatic amine and the amine salt, at least one of an acidic phosphate ester or an acidic thiophosphate ester having an OH group is preferably included as a phosphorus content of the extreme-pressure agent.
Similarly to any conventional lubricating oils, the lubricating oil according to the present invention may include a base oil and an additive mixed with the base oil.
The lubricating oil according to the present invention preferably includes a hydrocarbon oil as a base oil thereof, wherein a peak absorbency of the lubricating oil at infrared spectral wave numbers of 1,740±20 cm−1 is at most 1.5 in an infrared spectroscopic analysis using a fixed cell for liquid having an optical length of 0.05 mm±0.005 mm.
The base oil is preferably a non-ester base oil (hydrocarbon oil). As an ester content in the base oil is larger, the additive (FM) having a polar group is less adsorbed, meaning that the base oil preferably includes as little ester component as possible. The peak at the infrared spectral wave numbers of 1,740±20 cm−1 in the infrared spectroscopic analysis (FT-IR) indicates a peak of the ester content. Therefore, the base oil includes less ester as the peak absorbency at 1,740±20 cm−1 is smaller in the lubricating oil FT-IR.
The lubricating oil according to the present invention preferably exhibits a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis. In the 31P-nuclear magnetic resonance analysis (NMR), a peak assigned to the thiophosphate diester is detected at near 57 ppm, meaning that the lubricating oil exhibiting a peak of 57±2 ppm in NMR includes the thiophosphate diester. The lubricating oil including the thiophosphate diester can more effectively improve μ-ν characteristics toward positive gradient while preventing wear and seizure of the gear in the friction-type driving force transmission apparatus. When the peak of 57±2 ppm is exhibited in NMR, μ-ν characteristics can be effectively improved toward positive gradient, while wear and seizure of the gear are prevented from happening.
Given that the mass of the lubricating oil according to the present invention is 100%, a phosphorus content derived from a thiophosphate diester and/or an amine salt thereof is preferably 0.010% or more. The phosphorus content less than 0.010% is too small to fully exert an effect of the additive. The thiophosphate diester is preferably a compound expressed by expressed by Chemical Formula 5, and the amine salt of the thiophosphate diester is preferably a compound expressed by expressed by Chemical Formula 6.
A fourth lubricating oil according to the present invention is a lubricating oil used in a friction-type driving force transmission apparatus. The lubricating oil includes an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
The lubricating oil according to the present invention includes the aliphatic amine that can be mixed with the first lubricating oil and the additives respectively mixed with the second lubricating oil, thereby exerting the effects according to these inventions at once. When the aliphatic amine and/or the aliphatic amine ethylene oxide adduct and the phosphorous acid diester and/or phosphorous acid monoester are included in the lubricating oil according to the present invention, μ-ν characteristics favorably have positive gradient in the friction-type differential limiting device. More specifically, the lubricating oil including these additives, when applied to a friction surface of the friction-type differential limiting device, is thought to prevent solid contact thereon.
In the case where the saturated or unsaturated hydrocarbon group (hydrocarbon group expressed by R1 in Chemical Formula 1) of the aliphatic amine and the aliphatic amine ethylene oxide adduct has a carbon number equal to or less than 11, it fails to ensure an enough adsorption film thickness effective for preventing the solid contact. The hydrocarbon group with a carbon number equal to or more than 21 results in a lower polarity, reducing an adsorptivity to the friction surface.
The phosphorous acid diester (following Chemical Formula 7) and/or the phosphorous monoester (following Chemical Formula 8) is preferably included in the lubricating oil according to the present invention in a state where the aliphatic amine and an amine salt thereof are formed. The amine salt is oil-soluble, therefore, is homogeneously dissolved (dispersed) in the base oil of the lubricating oil. The amine salt thus homogeneously dissolved (dispersed) in the base oil of the lubricating oil without the occurrence of layer separation or deposition, when applied to a friction surface, can prevent solid contact thereon.
A fifth lubricating oil according to the present invention exhibits a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis. In the 31P-nuclear magnetic resonance analysis (NMR), a peak assigned to the thiophosphate diester is detected at near 57 ppm, meaning that the lubricating oil exhibiting a peak at 57±2 ppm in NMR includes the thiophosphate diester. The lubricating oil including the thiophosphate diester can more effectively improve μ-ν characteristics toward positive gradient while preventing wear and seizure of the gear in the friction-type driving force transmission apparatus. When the peak of 57±2 ppm is exhibited in NMR, μ-ν characteristics can be effectively improved toward positive gradient, while wear and seizure of the gear are prevented from happening.
Given that the mass of the lubricating oil according to the present invention is 100%, a phosphorus content derived from the thiophosphate diester and/or the thiophosphate diester amine salt is preferably 0.010% or more. The phosphorus content less than 0.010% is too small to fully exert an effect of the additive.
The amine salt of the thiophosphate diester is preferably a compound expressed by Chemical Formula 3, and the amine salt of the thiophosphate diester is preferably a compound expressed by Chemical Formula 8.
Given that the mass of the lubricating oil is 100%, at least one of an acidic phosphate ester and an acidic thiophosphate ester is preferably included so that a phosphorus content stays in a range of 0.20%≦P≦0.50%.
At least one of the acidic phosphate ester and the acidic thiophosphate ester is preferably included because, when used in a differential gear of the friction-type differential limiting device, wear and seizure of the gear are prevented from happening.
The phosphorus content below 0.20% by mass fails to ensure an enough wear resistance and seizure proofness. The phosphorus content exceeding 0.50% by mass overly accelerates a reactivity of an extreme-pressure agent, causing chemical wear or corrosion damage. The phosphorus content is more desirably 0.20% to 0.40% by mass.
The acidic phosphate ester and the acidic thiophosphate ester may be a monoester, diester, and triester, or a mixture of these esters.
The lubricating oil according to the present invention preferably includes a hydrocarbon oil as a base oil thereof, wherein a peak absorbency of the lubricating oil at infrared spectral wave numbers of 1,740±20 cm−1 is at most 1.5 in an infrared spectroscopic analysis using a fixed cell for liquid having an optical length of 0.05 mm±0.005 mm.
As described so far, the base oil of the lubricating oil according to the present invention is a non-ester base oil (hydrocarbon oil). As an ester content of the base oil is larger, the additive (FM) having a polar group is less adsorbed, meaning that the base oil preferably includes as little ester component as possible. The peak at the infrared spectral wave numbers of 1,740±20 cm−1 in the infrared spectroscopic analysis (FT-IR) indicates a peak of the ester content. Therefore, the base oil includes less ester as the peak absorbency at 1,740±20 cm−1 is smaller in the lubricating oil FT-IR.
First Friction Member
A friction member according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2).
Thus, the first lubricating oil is applied to the friction member according to the present invention. According to the friction member provided by the present invention, μ-ν characteristics of the friction member are improved toward positive gradient, and an expected quietness is ensured during the friction in the presence of the lubricating oil including the additive serving to prevent solid contact when applied to a surface of the friction member used in the friction-type driving force transmission apparatus.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a diamond-like carbon film formed thereon. A sliding movement of a friction member under demanding conditions (sliding movement at high contact pressures or high temperatures) wears a sliding surface of the friction member. The diamond-like carbon film (DLC film), when formed on the sliding surface, can control the wear of the friction member. The DLC film, which is not very aggressive against an opponent member, can slow down deterioration of the lubricating oil.
The DLC film may be formed on the sliding surface in a manner similar to any conventional DLC films. The film thickness of the DLC film may be suitably decided depending on sliding conditions of the friction members.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a tungsten carbide/diamond-like carbon film formed thereon, and a sliding surface of the other friction member is preferably nitrided. Further, the sliding surface of the other friction member is preferably made from an iron-based metal and then nitrided.
Similarly to the formation of the DLC film, the tungsten carbide/diamond-like carbon film (WC/C film), when formed on the sliding surface, can control the wear of the friction member. The WC/C film includes a multilayered structure where a tungsten carbide-enriched layer and a diamond-like carbon-enriched layer are alternately stacked on each other. The multilayered structure where the two layers are alternately stacked can prevent the friction members from wearing.
When the other sliding surface is nitrided, a nitrided film is formed thereon. The nitrided film having a high degree of hardness can prevent the friction member from wearing against aggression from the friction member where the WC/C film is formed.
The formations of the DLC film and the WC/C film are not particularly limited, and these film may be formed by any conventional methods. The film thicknesses of these films may be suitably decided without limitation depending on use conditions of the friction members.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members is preferably made from an iron-based metal, and a sliding surface of the other friction member is preferably nitrided. The friction member according to the present invention, though neither of the DLC film nor the WC/C film is formed thereon, can be prevented from wearing by the lubricating oil.
Second Friction Member
A friction member according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
Thus, the second lubricating oil is applied to the friction member according to the present invention. According to the friction member provided by the present invention, μ-ν characteristics of the friction member are improved toward positive gradient, and an expected quietness is ensured during the friction in the presence of the lubricating oil including the additive serving to prevent solid contact when applied to a surface of the friction member used in the friction-type driving force transmission apparatus.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a diamond-like carbon film formed thereon. A sliding movement of a friction member under demanding conditions (sliding movement at high contact pressures or high temperatures) wears a sliding surface of the friction member. The diamond-like carbon film (DLC film), when formed on the sliding surface, can control the wear of the friction member. The DLC film, which is not very aggressive against an opponent member, can slow down deterioration of the lubricating oil.
The DLC film may be formed on the sliding surface in a manner similar to any conventional DLC films. The film thickness of the DLC film may be suitably decided depending on sliding conditions of the friction members.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a tungsten carbide/diamond-like carbon film formed thereon, and a sliding surface of the other friction member is preferably nitrided. Further, the sliding surface of the other friction member is preferably made from an iron-based metal and then nitrided.
Similarly to the formation of the DLC film, the tungsten carbide/diamond-like carbon film (WC/C film), when formed on the sliding surface, can control the wear of the friction member. The WC/C film includes a multilayered structure where a tungsten carbide-enriched layer and a diamond-like carbon-enriched layer are alternately stacked on each other. The multilayered structure where the two layers are alternately stacked can prevent the friction members from wearing.
When the other sliding surface is nitrided, a nitrided film is formed thereon. The nitrided film having a high degree of hardness can prevent the friction member from wearing against aggression from the friction member where the WC/C film is formed.
The formations of the DLC film and the WC/C film are not particularly limited, and these film may be formed by any conventional methods. The film thicknesses of these films may be suitably decided without limitation depending on use conditions of the friction members.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members is preferably made from an iron-based metal, and a sliding surface of the other friction member is preferably nitrided. The friction member according to the present invention, though neither of the DLC film nor the WC/C film is formed thereon, can prevent the friction members from wearing by the lubricating oil.
Third Friction Member
A friction member according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including: at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2); and at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
Thus, the third lubricating oil is applied to the friction member according to the present invention. According to the friction member provided by the present invention, μ-ν characteristics of the friction member are improved toward positive gradient, and an expected quietness is ensured during the friction in the presence of the lubricating oil including the additive serving to prevent solid contact when applied to a surface of the friction member used in the friction-type driving force transmission apparatus.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a diamond-like carbon film formed thereon. A sliding movement of a friction member under demanding conditions (sliding movement at high contact pressures or high temperatures) wears a sliding surface of the friction member. The diamond-like carbon film (DLC film), when formed on the sliding surface, can control the wear of the friction member. The DLC film, which is not very aggressive against an opponent member, can slow down deterioration of the lubricating oil.
The DLC film may be formed on the sliding surface in a manner similar to any conventional DLC films. The film thickness of the DLC film may be suitably decided depending on sliding conditions of the friction members.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a tungsten carbide/diamond-like carbon film formed thereon, and a sliding surface of the other friction member is preferably nitrided. Further, the sliding surface of the other friction member is preferably made from an iron-based metal and then nitrided.
Similarly to the formation of the DLC film, the tungsten carbide/diamond-like carbon film (WC/C film), when formed on the sliding surface, can control the wear of the friction member. The WC/C film includes a multilayered structure where a tungsten carbide-enriched layer and a diamond-like carbon-enriched layer are alternately stacked on each other. The multilayered structure where the two layers are alternately stacked can prevent the friction members from wearing.
When the other sliding surface is nitrided, a nitrided film is formed thereon. The nitrided film having a high degree of hardness can prevent the friction member from wearing against aggression from the friction member where the WC/C film is formed.
The formations of the DLC film and the WC/C film are not particularly limited, and these film may be formed by any conventional methods. The film thicknesses of these films may be suitably decided without limitation depending on use conditions of the friction members.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members is preferably made from an iron-based metal, and a sliding surface of the other friction member is preferably nitrided. The friction member according to the present invention, though neither of the DLC film nor the WC/C film is formed thereon, can be prevented from wearing by the lubricating oil.
Fourth Friction Member
A fourth friction member according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil exhibiting a peak of 57±2 ppm in a 31P-nuclear magnetic resonance analysis.
Thus, the fifth lubricating oil is applied to the friction member according to the present invention. According to the friction member provided by the present invention, μ-ν characteristics of the friction member are improved toward positive gradient, and an expected quietness is ensured during the friction in the presence of the lubricating oil including the additive serving to prevent solid contact when applied to a surface of the friction member used in the friction-type driving force transmission apparatus.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a diamond-like carbon film formed thereon. A sliding movement of a friction member under demanding conditions (sliding movement at high contact pressures or high temperatures) wears a sliding surface of the friction member. The diamond-like carbon film (DLC film), when formed on the sliding surface, can control the wear of the friction member. The DLC film, which is not very aggressive against an opponent member, can slow down deterioration of the lubricating oil.
The DLC film may be formed on the sliding surface in a manner similar to any conventional DLC films. The film thickness of the DLC film may be suitably decided depending on sliding conditions of the friction members.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members preferably has a tungsten carbide/diamond-like carbon film formed thereon, and a sliding surface of the other friction member is preferably nitrided. Further, the sliding surface of the other friction member is preferably made from an iron-based metal and then nitrided.
Similarly to the formation of the DLC film, the tungsten carbide/diamond-like carbon film (WC/C film), when formed on the sliding surface, can control the wear of the friction member. The WC/C film includes a multilayered structure where a tungsten carbide-enriched layer and a diamond-like carbon-enriched layer are alternately stacked on each other. The multilayered structure where the two layers are alternately stacked can prevent the friction members from wearing.
When the other sliding surface is nitrided, a nitrided film is formed thereon. The nitrided film having a high degree of hardness can prevent the friction member from wearing against aggression from the friction member where the WC/C film is formed.
The formations of the DLC film and the WC/C film are not particularly limited, and these film may be formed by any conventional methods. The film thicknesses of these films may be suitably decided without limitation depending on use conditions of the friction members.
The friction member according to the present invention is characterized in that, of a pair of friction members sliding with each other, a sliding surface of one of the friction members is preferably made from an iron-based metal, and a sliding surface of the other friction member is preferably nitrided. The friction member according to the present invention, though neither of the DLC film nor the WC/C film is formed thereon, can be prevented from wearing by the lubricating oil.
First Differential with a Differential Limiting Function
A gear-type differential with a differential limiting function according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2).
Thus, the first lubricating oil is applied to the differential with a differential limiting function according to the present invention. According to the differential with a differential limiting function provided by the present invention, μ-ν characteristics of the friction member are improved toward positive gradient, and an expected quietness is ensured during the friction in the presence of the lubricating oil including the additive serving to prevent solid contact when applied to a surface of the friction member used in the friction-type driving force transmission apparatus.
The gear-type differential with a differential limiting function according to the present invention is a driving force transmission apparatus, including: a plurality of planetary gears; a planetary carrier for supporting the plurality of planetary gears so that the plurality of planetary gears are orbitally revolvable and rotatable on their own rotational axes; and a pair of gears disposed coaxial with the planetary carrier and differentially rotatable via the planetary gears, wherein a lubricating oil is applied to between sliding surfaces of the planetary gears and the planetary carrier.
The differential with a differential limiting function according to the present invention is a differential wherein a torque is distributed by the planetary gears, and a high contact pressure is applied to the sliding surfaces of the planetary gears and the planetary carrier. Under such demanding conditions, μ-ν characteristics are improved toward positive gradient, and an expected quietness is ensured as far as the lubricating oil is applied to between the sliding surfaces.
Second Differential with a Differential Limiting Function
A gear-type differential with a differential limiting function according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
Thus, the second lubricating oil is applied to the differential with a differential limiting function according to the present invention. According to the differential with a differential limiting function provided by the present invention, μ-ν characteristics of the friction member are improved toward positive gradient, and an expected quietness is ensured during the friction in the presence of the lubricating oil including the additive serving to prevent solid contact when applied to a surface of the friction member used in the friction-type driving force transmission apparatus.
The gear-type differential with a differential limiting function according to the present invention is a driving force transmission apparatus, including: a plurality of planetary gears; a planetary carrier for supporting the plurality of planetary gears so that the plurality of planetary gears are orbitally revolvable and rotatable on their own rotational axes; and a pair of gears disposed coaxial with the planetary carrier and differentially rotatable via the planetary gears, wherein a lubricating oil is applied to between sliding surfaces of the planetary gears and the planetary carrier.
The differential with a differential limiting function according to the present invention is a differential wherein a torque is distributed by the planetary gears, and a high contact pressure is applied to the sliding surfaces of the planetary gears and the planetary carrier. Under such demanding conditions, μ-ν characteristics are improved toward positive gradient, and an expected quietness is ensured as far as the lubricating oil is applied to between the sliding surfaces.
Third Differential with a Differential Limiting Function
A gear-type differential with a differential limiting function according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil including: at least one of an aliphatic amine having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 1) and an aliphatic amine ethylene oxide adduct having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 2); and at least one of a phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 3) and a phosphorous acid monoester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 20 (expressed by Chemical Formula 4).
Thus, the third lubricating oil is applied to the differential with a differential limiting function according to the present invention. According to the differential with a differential limiting function provided by the present invention, μ-ν characteristics of the friction member according to the present invention are improved toward positive gradient, and an expected quietness is ensured during the friction in the presence of the lubricating oil including the additive serving to prevent solid contact when applied to a surface of the friction member used in the friction-type driving force transmission apparatus.
The gear-type differential with a differential limiting function is a driving force transmission apparatus, including: a plurality of planetary gears; a planetary carrier for supporting the plurality of planetary gears so that the plurality of planetary gears are orbitally revolvable and rotatable on their own rotational axes; and a pair of gears disposed coaxial with the planetary carrier and differentially rotatable via the planetary gears, wherein a lubricating oil is applied to between sliding surfaces of the planetary gears and the planetary carrier.
Fourth Differential with a Differential Limiting Function
A fourth gear-type differential with a differential limiting function according to the present invention is characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, the lubricating oil exhibiting a peak of 57±2 ppm in a P-nuclear magnetic resonance analysis.
The fourth differential with a differential limiting function according to the present invention is a gear-type differential with a differential limiting function characterized in that a lubricating oil used in a friction-type driving force transmission apparatus is applied thereto, wherein, given that the mass of the lubricating oil is 100%, a phosphorus content of the lubricating oil derived from at least one of a thiophosphate diester (expressed by Chemical Formula 5) and an amine salt thereof (expressed by Chemical Formula 6) is at least 0.010%.
Thus, the lubricating oil thus characterized is applied to the differential with a differential limiting function according to the present invention. According to the differential with a differential limiting function provided by the present invention, μ-ν characteristics of the friction member according to the present invention are improved toward positive gradient, and an expected quietness is ensured during the friction in the presence of the lubricating oil including the additive serving to prevent solid contact when applied to a surface of the friction member used in the friction-type driving force transmission apparatus.
The gear-type differential with a differential limiting function is a driving force transmission apparatus, including: a plurality of planetary gears; a planetary carrier for supporting the plurality of planetary gears so that the plurality of planetary gears are orbitally revolvable and rotatable on their own rotational axes; and a pair of gears disposed coaxial with the planetary carrier and differentially rotatable via the planetary gears, wherein a lubricating oil is applied to between sliding surfaces of the planetary gears and the planetary carrier.
First to Fourth Differentials with a Differential Limiting Function
Any of the differentials with a differential limiting function according to the inventions described so far is specifically a center differential with a differential limiting function structurally characterized as illustrated in
A center differential with a differential limiting function 1 illustrated in
As illustrated in
The support portion 11 is formed in a substantially cylindrical shape and has a plurality of holding apertures 13 axially extending. These holding apertures 13 are spaced at equal intervals along a circumferential direction of the support portion 11. The holding apertures 13 have a circular shape in cross section, and inner diameters of the holding apertures 13 are almost equal to outer diameters of the planetary gears 5. The inner diameters of the holding apertures 13 are larger than a radial thickness of the support portion 11. A wall surface 13a of each holding aperture 13 has two openings 15a and 15b which are respectively open on outer and inner peripheries of the support portion 11. When the planetary gears 5 are inserted in the holding apertures 13, the planetary gears 5 are rotatably supported with top lands 5a thereof slidably contacting the wall surfaces 13a of the holding apertures 13 and further meshed with the ring gear 3 and the sun gear 4 through the openings 15a and 15b formed on two radial sides of the wall surfaces 13a. In the center differential with a differential limiting function 1, helical gears are used as the planetary gears 5.
As illustrated in
The housing 2 is coupled with the diametrically large portion 18 of the output member 16 to rotate integral with the output member 16 and the ring gear 3. The planetary carrier 6 is supported by a bearing (needle bearing) 20 interposed between the shaft portion 10 thereof and the diametrically large portion 18 of the output member 16 to be rotatable relative to the output member 16 and the ring gear 3. The sun gear 4 has a hollow inside, and an end part of the sun gear 4 is externally mounted in a rotatable manner on an end part of the shaft portion 10 of the planetary carrier 6. Accordingly, the sun gear 4 is supported rotatably relative to the planetary carrier 6.
The sun gear 4, the shaft portion 10 of the planetary carrier 6, and the shaft portion 17 of the output member 16 are provided with spline-fitting portions 4a, 10a, and 17a respectively formed in inner peripheries thereof. In the center differential with a differential limiting function 1, the spline-fitting portion 10a formed in the shaft portion 10a of the planetary carrier 6 constitutes a drive torque input unit, and the spline-fitting portion 4a of the sun gear 4 and the spline-fitting portion 17a formed in the shaft portion 17 of the output member 16 respectively constitute a first output unit and a second output unit.
When the planetary gears 5 supported by the planetary carrier 6 are orbitally revolved and rotated on their own rotational axes, a drive torque input to the planetary carrier 6 is transmitted by the orbital revolution and the rotation of the planetary gears 5 supported by the planetary carrier 6 with a differential therebetween being allowed. The transmitted drive torque is input to the sun gear 4 and the ring gear 3 (output member 16) meshed with the respective planetary gears 5 by a predefined distribution ratio. The center differential with a differential limiting function 1 is configured as a center differential gear of a four-wheel drive car, wherein the sun gear 4 constituting the first output unit is coupled with a drive shaft on front-wheel side and the output member 16 constituting the second output unit is coupled with a drive shaft on rear-wheel side. When a torque reaction force is generated in a drive system of the car, the differential is limited based on a thrusting force resulting from a rotational reaction force between the gears meshed with each other and a frictional force between the sliding surfaces which are the top lands 5a and planetary carrier 6-side sliding surfaces of the planetary gears 5 (wall surfaces 13a of the holding apertures 13).
The wall surfaces 13a of the holding apertures 13 serving as the sliding surfaces are preferably nitrided (for example, ion nitriding or gas nitrocarburizing). The top lands 5a of the planetary gears 5 are preferably treated so that multiple thin layers of tungsten carbide/diamond-like carbon are formed thereon.
The sliding surfaces of the center differential with a differential limiting function 1 illustrated in
Hereinafter, the present invention is described in further detail referring to examples.
Preparation of Lubricating Oil
In examples of the present invention, lubricating oils (sample oils A-W) were prepared.
Sample Oil A is prepared from a commercially available gear oil (differential gear oil, viscosity grade: 75W-85, hereinafter called sample oil F) used as a base oil, Oleyl amine (supplied by Lion Corporation, trade name: AMINE OD) which is an aliphatic amine having an unsaturated hydrocarbon group with a carbon number of 18 expressed by the following Chemical Formula 9 by 3.0% by mass, and Dioleyl Hydrogen Phosphite (supplied by Johoku Chemical Co., Ltd., trade name: JP-218-OR) which is a phosphorous acid diester expressed by the following Chemical Formula 10 by 1.52% by mass. The percentages by mass of the oleyl amine and the dioleyl hydrogen phosphite to be added are expressed given that the mass of the prepared lubricating oil is 100% (mass percentages hereinafter described are similarly expressed).
Sample Oil B is prepared from the sample oil F used as a base oil, Polyoxyethylene Oleylamine (supplied by Lion Corporation, trade name: Esomin O/12) which is an aliphatic amine ethylene oxide adduct having an unsaturated hydrocarbon group with a carbon number of 18 (oleyl group) expressed by the following Chemical Formula 11 where x+y equals 2 (more specifically, x and y are both 1) by 3.0% by mass, and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 6 by 1.52% by mass.
Sample Oil C is prepared from the sample oil F used as a base oil, Polyoxyethylene Oleylamine (supplied by Lion Corporation, trade name: Esomin O/20) which is an amine ethylene oxide adduct having an unsaturated hydrocarbon group with a carbon number of 18 (oleyl group) expressed by Chemical Formula 11 where x+y equals 10 by 3.0% by mass, and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 6 by 1.52% by mass.
Sample Oil D is prepared from the mixture of sample oil F and a commercial available gear oil (hypoid gear oil LSD, viscosity grade: 85W-90, hereinafter called sample oil G) by 50:50 percentage by mass, Oleylamine expressed by Chemical Formula 5 was further added by 3.0% by mass, Dioleyl Hydrogen Phosphite expressed by Chemical Formula 6 was further added by 1.52% by mass.
Sample Oil E is prepared from the sample oil G, Oleylamine expressed by Chemical Formula 9 by 3.0% by mass, and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 6 by 1.52% by mass.
The sample oil H is a commercially available gear oil (differential gear oil, viscosity grade: 75W-85).
Sample Oils I and J are prepared from the sample oil F used as a base oil, Oleylamine expressed by Chemical Formula 9 by respectively 0.1% by mass (sample oil I) and by 1.0% by mass (sample oil J), and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 6 was further added to the resulting oils by 1.52% by mass.
Sample oils K and L are prepared from the sample oil F used as a base oil, Oleylamine expressed by Chemical Formula 9 by 3.0% by mass, and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 10 by 0.1 mass (sample oil K) and by 1.0% by mass (sample oil L).
Sample Oil M is prepared from the sample oil F used as a base oil, Oleylamine expressed by Chemical Formula 9 by 3.0% by mass.
Sample Oil N is prepared from the sample oil F used as a base oil, Dioleyl Hydrogen Phosphite expressed by Chemical Formula 10 by 1.52% by mass.
Sample Oil O is prepared from the sample oil F used as a base oil, Hexylamine (supplied by Tokyo Chemical Industry Co., Ltd., trade name: Hexylamine) which is an aliphatic amine having a saturated hydrocarbon group with a carbon number of 6 expressed by the following Chemical Formula 12 by 1.14% by mass, and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 10 by 1.52% by mass, where a nitrogen content of the prepared sample oil was equal to that of the sample oil A.
C6H13—NH2 [Chemical Formula 12]
Sample Oil P is prepared from the sample oil F used as a base oil, Dodecylamine (supplied by Lion Corporation, trade name: Amine 12D) which is an aliphatic amine having a saturated hydrocarbon group with a carbon number of 12 expressed by the following Chemical Formula 13 by 2.08% by mass, and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 10 by 1.52% by mass, where a nitrogen content of the prepared sample oil was equal to that of the sample oil A.
C12H25—NH2 [Chemical Formula 13]
Sample Oil Q is prepared from the sample oil F used as a base oil, Oleylamine expressed by the following Chemical Formula 9 by 3.0% by mass, and Diethyl Hydrogen Phosphite (supplied by Johoku Chemical Co., Ltd., trade name: JP-202) which is a phosphorous acid diester having a saturated hydrocarbon group with a carbon number of 2 expressed by the following Chemical Formula 14 by 0.35% by mass, where a phosphorus content of the prepared sample oil was equal to that of the sample oil A.
Sample Oil R is prepared from the sample oil F used as a base oil, Oleylamine expressed by the Chemical Formula 9 by 3.0% by mass, and Dilauryl Hydrogen Phosphite (supplied by Johoku Chemical Co., Ltd., trade name: JP-213-D) which is a phosphorous acid diester having a saturated hydrocarbon group with a carbon number of 12 expressed by the following Chemical Formula 15 by 1.16% by mass, where a phosphorus content of the prepared sample oil was equal to that of the sample oil A.
The sample oil S is a non-ester hydrocarbon-containing base oil which is a Group III hydrogenated purified mineral oil commercially available (supplied by SK Lubricants Co., Ltd., trade name: YUBASE 4).
The sample oil T is a diester-containing base oil commercially available (supplied by Kao Corporation, trade name: VINYCIZER 50).
Sample Oil U is prepared from the sample oil S used as a base oil, Oleylamine expressed by Chemical Formula 9 by 3.0% by mass, and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 10 by 1.52% by mass.
Sample Oil V is prepared from the sample oil T used as a base oil, Oleylamine expressed by Chemical Formula 9 by 3.0% by mass, and Dioleyl Hydrogen Phosphite expressed by Chemical Formula 10 by 1.52% by mass.
Sample oil W is prepared from sample oil V by 10% by mass, and the sample oil U by 90% by mass.
The compositions of the sample oils A to W are recited in Tables 1 to 4. Tables 1 to 4 recite an analysis result on whether the phosphate ester, thiophosphate ester, and amine salt were contained in the sample oils and further recite an analysis result of the phosphorus contents and types of the base oils of the respective sample oils.
After the sample oils A to E, I to R, and U to W were prepared, they were left at rest at room temperature for over a week. Then, the sample oils were visually observed.
Of all of the visually observed sample oils, there were neither separated layers nor deposited materials in any of the sample oils but the sample oil C. This confirmed that the materials were uniformly mixed in these sample oils and the FMs respectively added to the sample oils were evenly dissolved (dispersed) therein. The sample oils, where the FMs were dissolved (dispersed) in the base oils with neither separated layers nor deposited materials, can effectively avoid solid contact when they are applied to the friction surfaces.
In contrast to these sample oils, after the sample oil C containing the polyoxyethylene oleylamine which is the amine ethylene oxide adduct having an unsaturated hydrocarbon group with a carbon number of 18 expressed by Chemical Formula 11 where x+y equals 10 was left at rest at room temperature for 12 hours or more, the layer separation was detected, indicating that the uniform mixing failed in this sample oil.
On the other hand, the uniform mixing was confirmed in the sample oil B containing the polyoxyethylene oleylamine which is the aliphatic amine ethylene oxide adduct having an unsaturated hydrocarbon group with a carbon number of 18 expressed by Chemical Formula 11 where x+y equals 2.
This demonstrates that the solubility of the aliphatic amine ethylene oxide adduct in the base oils lowers as x+y is larger. It is known from the result that x+y is preferably about 2±1 when the aliphatic amine ethylene oxide adduct is dissolved in the base oils.
Analysis of Phosphate Ester and Thiophosphate Ester
The sample oils F, G, H, N, M, A, and E were analyzed by a 31P-nuclear magnetic resonance analysis (Nuclear Magnetic Resonance: hereinafter abbreviated to NMR). An analyzer, ECA-500, supplied by JEOL Ltd. was used for single pulse measurement by proton decoupling. CDCl3 (deuterated chloroform) was used as a measurement solvent, and PO4 was a reference value (0 ppm) of chemical shift.
a) to (c) illustrate 31P-NMR spectra of the sample oils F, G, and H. Referring to the illustrations of
According to the results illustrated the drawings, each of the sample oils A, B, D, and I to R which is the sample oil F mixed with the additives and the sample oil E which is the sample oil G mixed with the additive include phosphate esters and thiophosphate esters.
It is confirmed from the illustrations of
It is confirmed that a peak intensity of the thiophosphate diester (peak with ▪ in the drawings) is high in the sample oil A (
No distinct peak assigned to the thiophosphate diester can be confirmed at near 57 ppm in the NMR spectra of the reference sample oil F (
In the NMR spectra of
As illustrated in
Analysis of Amine Salt Formation
The sample oils A, B, E, F, G, J, L, P, R, S, and U were subjected to a Fourier transform infrared spectroscopic analysis (FT-IR). Avatar 360 supplied by Thermo Nicolet Corporation was used as an analyzer to perform IR spectrum measurement 32 times by the use of a KBr fixed cell for liquid having an optical length of 0.10 mm. The same analyzer was used for IR spectrum measurement of the additives alone according to single reflection ATR.
In all of the illustrations of spectral subtraction in
The broad peaks at near the wave number of 2,900 cm−1 in the illustrations of spectral subtraction in
Referring to
Referring to
Analysis of Acidic Phosphate Ester Amine Salt
The dioleyl hydrogen phosphite expressed by Chemical Formula 6 was added by 1.52% by mass to the sample oil S including the hydrocarbon-containing base oil to prepare a model sample oil a.
The sample oil U which is the sample oil containing the oleylamine by 3.0% by mass and the dioleyl hydrogen phosphite expressed by Chemical Formula 6 by 1.52% by mass, and the model sample oil a were subjected to an NMR analysis in a similar manner.
In
According to the NMR spectrum of
It is known from these results that the amine salt of the acidic phosphate ester expressed by Chemical Formulas 7 and 8 is formed in the sample oil U containing the oleylamine and dioleyl hydrogen phosphite.
According to the uniformity observation of each of the prepared oils, neither separation of layers nor deposited materials was detected in the sample oil U uniformly mixed. This led to the confirmation that the generated amine salt of the acidic phosphate ester is oil-soluble.
Composition Analysis of Ester-Containing Base Oils
The sample oils A, B, D, E, F, G, U, V, and W were subjected to Fourier transform infrared spectroscopic analysis (FT-IR).
Avatar 360 supplied by Thermo Nicolet Corporation was used as an analyzer to perform IR spectrum measurement 32 times by the use of a KBr fixed cell for liquid having an optical length of 0.05 mm.
The spectra of the sample oils A, B, D, F, V, and W in the drawings show peaks associated with the ester structure at near the wave numbers of 1,740 cm−1 and 1,170 cm−1. All of the sample oils show an absorbency exceeding 1.0 at their peak intensities near 1,740 cm−1. It is known from the result that all of the sample oils have high ester contents in their whole compositions and these peaks are irrelevant to the additives thereof but are mostly associated with their base oils.
In any of the sample oils A, B, F, V, and T illustrated in
As recited in Tables 1 to 4, it can be determined from these results that the sample oils A, B, D, F, V, T, and W include the ester-containing base oils as their base oils. Of these sample oils, however, the sample oils D and W contain relatively small volumes of ester-containing base oils. On the other hand, the principal ingredients of the sample oil G, the sample oil E containing the sample oil G as its base oil, and the sample oil U are the hydrocarbon-containing base oils.
Evaluation
The friction characteristics of the respective sample oils were assessed.
Evaluation Method and Evaluation Result
A friction test was performed by the use of a ring-on-block friction test apparatus supplied by Takachihoseiki Co., Ltd. Describing the friction test performed by the test apparatus, a block member is subject to a load and a ring member is rotated to cause a friction therebetween (sliding movement) as shown in
b) and (c) are illustrations of the block and ring members with dimensions thereof. Describing the ring member, a WC/C film having a thickness of about 3 μm (a multilayered structure where a tungsten carbide-enriched layer and a diamond-like carbon-enriched layer are alternately stacked on each other) is formed on carburized SCM 420. The block member was plasma-nitrided FCD 600. The ring member had a surface roughness of 7 to 10 μm in ten point height of irregularities RzJIS (JIS B 0601:2001), and the block member had a surface roughness of 3 to 5 μm ten point height of irregularities RzJIS.
During the friction test, oil temperatures were set to normal temperature (30° C.), and a performance measurement pattern was applied after a running-in pattern was repeated twice.
It is confirmed from
The friction test by the friction test apparatus was further performed, in which SCMB 21 carburized and then sulphonitrided was used as the ring member and nitrocarburized FCD 600 was used as the block member to measure the μ-ν gradients. The same test conditions were applied.
As illustrated in
The sample oils A, O, and P are the lubricating oils obtained by adding the aliphatic amine to the sample oil F, where the hydrocarbon group of the aliphatic amine is differently structured (carbon number of the hydrocarbon group is different). As illustrated in
The sample oils A and B are the lubricating oils obtained by adding the aliphatic amine or the aliphatic amine ethylene oxide adduct, respectively, to the sample oil F, where the additive is differently structured. Referring to
These sample oils are the lubricating oils obtained by adding the aliphatic amine or the aliphatic amine ethylene oxide adduct, respectively, to the sample oil F, where the mass % of the additive to be added is different. Referring to
These sample oils are the lubricating oils obtained by adding the phosphorous acid diester having an unsaturated hydrocarbon group to the sample oil M, where the carbon number of the hydrocarbon group of the additive is different. As illustrated in
These sample oils are the lubricating oils obtained by adding the phosphorous acid diester to the sample oil M, where the additive is differently structured. As illustrated in
The sample oil A is the lubricating oil obtained by adding the aliphatic amine and the phosphorous acid diester to the sample oil F which is an ester-based lubricating oil. Referring to
The sample oil E is the lubricating oil obtained by adding the aliphatic amine and the phosphorous acid diester to the sample oil G which is a non-ester lubricating oil. Referring to
The sample oil U, S+phosphorous acid diester, and S+aliphatic amine are the lubricating oils obtained by adding the aliphatic amine and/or phosphorous acid diester to the sample oil S which is a mineral oil. As illustrated in
The sample oil V is the lubricating oil obtained by adding the aliphatic amine and the phosphorous acid diester to the sample oil T which is an ester-based lubricating oil. According to the illustration of
Thus, it was learnt from the illustrations of
The sample oils (sample oils A, J, L, P, and R) are the lubricating oils in which the aliphatic amine and the phosphorous acid diester were both added to the sample oil F, where these additives form the amine salt. It was confirmed from the illustration of
The μ-V gradients of the sample oils S and U were measured and observed (see
The sample oil A contains the sample oil
F as its base oil, and the sample oil E contains the sample oil G as its base oil. The sample oil D contains a mixture of the sample oils F and G as its base oil. It was known from the illustration of
The sample oil V contains the sample oil T as its base oil, and the sample oil U contains the sample oil S as its base oil. The sample oil W is a mixture of the sample oils V and U, and contains mixture of the sample oils S and T as its base oil. It was known from the illustration of
It was learnt from the illustrations of
The sample oil A is the lubricating oil obtained by adding the phosphorous acid diester to the sample oil F. The sample oil E is the lubricating oil obtained by adding the phosphorous acid diester to the sample oil G. It is known from the illustrations of
According to the running-in pattern wherein a pressing force was set to 294 N (309 MPa), sliding velocity was set to 160 rpm (0.293 m/s), and sliding time was set to 30 minutes, the μ-ν characteristics of the sample oils U and V were measured in the friction test apparatus. The performance measurement pattern was similar to that of the friction test.
As illustrated in
The sliding surfaces of the blocks tested by the friction test apparatus where the μ-ν gradients were measured were analyzed by the TOF-SIMS analysis.
It was confirmed from the illustration of
The sliding surfaces of the blocks tested by the friction test apparatus were analyzed by the TOF-SIMS analysis.
It was confirmed from the illustration of
The sliding surfaces of the blocks tested by the friction test apparatus were analyzed by an XPS analysis, a result of which is illustrated in
Referring to the illustration of
In the sample oil E, a degree of degradation of the μ-ν gradient is relatively small due to the fluid thermal degradation. This is because the FM, which may be degraded and thereby diminished, is still effectively adsorbed to the friction surface in the sample oil E whose base oil is not an ester-containing base oil having a polar group.
As recited in Tables 1 to 4, the sample oils A and B, D to E, I to P, R, and U to W contain the aliphatic amine or the aliphatic amine ethylene oxide adduct having an unsaturated hydrocarbon group with a carbon number of 12 to 18, and the phosphorous acid diester having a saturated or unsaturated hydrocarbon group with a carbon number of 12 to 18. These additives are generally known to form an organic adsorption film on a friction surface. The organic adsorption film thus obtained is thought to reduce a friction coefficient under low sliding velocity conditions where a ratio of solid contacts increases as an average oil film thickness lessens in the presence of solid contact and oil film forming areas both, improving the μ-ν characteristics toward positive gradient. An adsorption-desorption balance of the additive decides a state of formation of the adsorption film. Therefore, the μ-ν characteristics are different depending on the state of formation of the adsorption film on the friction surface.
In the case of any lubricating oils not including these effective additive, for example, lubricating oils commercially available, an adsorption film strong enough is not formed on the friction surface as illustrated in
Because of the reasons described so far, the sample oils according to the present invention containing the particular additives can obtain such favorable μ-ν characteristics. The sample oils according to the present invention can ensure remarkable quietness in any friction-type differential limiting devices.
It was confirmed that an effective way to improve the μ-ν characteristics toward positive gradient is to reduce a percentage by mass of the ester-containing base oil and increase the hydrocarbon-containing base oil as a principal additive in the lubricating oil as in the sample oils D and E.
The adsorption of the additive is likely to inhibit adsorption of the other ingredients of the lubricating oil. A base oil ingredient with polarity, for example, diester or polyol ester with two ester bonds in a molecule, achieves such a high adsorptivity, undermining adsorption of any effective additives. More specifically, when a lubricating oil including any ester-containing base oil is used, the formation of an enough desorption film on the friction surface is inhibited even when a large volume of additives (amine and phosphorous acid diester having an alkenyl group) is added thereto.
When the additives are added (by 1% by mass or more), favorable μ-ν characteristics (or favorable quietness) are maintained over a long period of time as demonstrated by the sample oils according to the present invention. The additives of the lubricating oil are oxidized, thermally deteriorated, or degenerated or decomposed through adsorption to the friction surface during use. When the lubricating oil is short of an effective amount of additives as a result of the degeneration and/or decomposition, it is no longer possible to form a dense and strong adsorption film on the friction surface. To avoid such a problem, when the additives are added (by 1% by mass or more) as demonstrated by the sample oils according to the present invention, a long-term use does not overly consume an effective amount of additives, and favorable μ-ν characteristics (or favorable quietness) are accordingly maintained over a long period of time.
The sample oils according to the present invention succeed in remarkable quietness (positive μ-ν gradient) in friction members, particularly in sliding members both made of iron-based metals and sliding members respectively made of an iron-based metal and a hard coating.
When the sample oils representing the lubricating oil according to the present invention, which succeeds in improving the μ-ν characteristics toward positive gradient, are used in the differential with a differential limiting function illustrated in
The sample oils according to the present invention may be used in differentials with a differential limiting function illustrated in
A differential with a differential limiting function 8 illustrated in
Coupling gears 85, 86, 87, and 88 are operably coupled so that the two side gears 83 and 84 rotate by an equal amount in opposite directions relative to the housing 80. The coupling gears 85 to 88 each forms a train of gears and couples the two side gears 83 and 84 with each other. The housing 80 has a pedestal, and the pedestal has windows formed therein for the coupling gears respectively paired to be located away from each other through equal angles in two different directions from the side gears. The coupling gears are each retained in the window to be rotated on a shaft line thereof by a journal pin 850. The journal pine 850 is supportably inserted in a hole formed in the pedestal.
The coupling gears 85 to 88 each has an intermediate gear portion 851 formed as a worm wheel (though the gear 85 alone is illustrated with reference numerals in
According to the present modified embodiment, sliding surfaces are; between the coupling gears 85 to 88 and the side gears 83, 84, between the pair of drive shafts 81 and 82, between the drive shafts 81, 82 and the housing 80 (washer provided therein), between axial end faces of the coupling gears 85 to 88 and the housing 80, and between the journal pins 850 of the coupling gears 85 to 88 and the housing 80.
According to the present modified embodiment, preferably, wall surfaces of the windows, which are sliding surfaces slidably contacted by the coupling gears 85 to 88, are nitrided (for example, ion nitriding or gas nitrocarburizing), and faces of the coupling gears 85 to 88 each has a tungsten carbide/diamond-like carbon film formed thereon.
A differential with a differential limiting function 9 illustrated in
The side gears 85 and 86 have teeth tilting in a direction through an equal tilting angle relative to a common rotational shaft (for example, tilting to right or left). A thrust force is generated depending on a torque transmitted from the housing 90 to the drive shafts 92, 93.
According to the present modified embodiment, sliding surfaces are; between the element gears 94 to 97 and the housing 90, between the pair of drive shafts 92 and 93, between the drive shafts 92, 93 and the housing 90 (washer provided therein), between axial end faces of the element gears 94 to 97 and the housing 90, and between the element gears 94 to 97 and the side gears 920, 930.
According to the present modified embodiment, preferably, wall surfaces of the housing 90 slidably contacted by the element gears 94 to 97 are nitrided (for example, ion nitriding or gas nitrocarburizing), and top lands of the element gears 94 to 97 each has a tungsten carbide/diamond-like carbon film formed thereon.
When any of the sample oils is applied to between the sliding surfaces according to these modified embodiments, remarkable quietness (μ-V characteristics with positive gradient) can be attained.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-264415 | Nov 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/070750 | 11/19/2010 | WO | 00 | 7/10/2012 |
