Grease composition for constant velocity joint, and constant velocity joint in which said grease composition is sealed

Abstract

Provided is a grease composition for a constant velocity joint. A lubricating oil composition containing (a) a base oil having a kinematic viscosity at 100 DEG C of 16.0 mm2 / s or more and a viscosity index of 90 or more, (b) a diurea-based thickener such as aliphatic diurea, (c) 0.2-2.0 mass% of zinc dialkyldithiophosphate, (d) 0.5-2.0 mass% of non-oil-soluble molybdenum dialkyldithiocarbamate, (e) 0.5-3.0 mass% of oil-soluble molybdenum dialkyldithiocarbamate, (f) 1.0-4.0 mass% of zinc dialkyldithiocarbamate, and (g) 0.1-1.5 mass% of benzothiazolethione or a derivative thereof, and (f): (g) = 8: 1-3: 1 (mass ratio).

Description

Technical Field

[0001] The present invention relates to a grease composition for a constant velocity joint and a constant velocity joint enclosing the grease composition. Background Art

[0002] Among automobiles, FF vehicles are widely used from the viewpoint of reducing weight and ensuring living space for the purpose of environmental measures (CO2 reduction) for vehicles, and constant velocity joints (CVJs) are used, which are indispensable for power transmission in FF vehicles.

[0003] CVJ is a device that transmits rotation between two shafts while rotating at an angle, so inside the universal joint, the parts perform complex rolling and sliding motions with each other. The telescopic CVJ among CVJs also has an axial sliding mechanism, so the friction between the parts inside the universal joint will generate sliding resistance in the axial direction. If this sliding resistance is large, it may cause vibration and noise.

[0004] In recent years, due to the changes in vehicle specifications accompanied by noise restrictions and the need to improve fuel efficiency, telescopic constant velocity joints are sometimes exposed to high temperature environments. In order to ensure durability (peeling resistance) and durability at high temperatures, initial running-in is required. Initial running-in refers to the smoothing of undulations and irregularities on the surface of the joint caused by the processing of the joint after the joint is used.

[0005] As CVJ greases having excellent spalling resistance at room temperature, there have been proposed greases in which zinc dialkyldithiophosphate, molybdenum dialkyldithiocarbamate, zinc dialkyldithiophosphate, and a sulfur-nitrogen extreme pressure additive are blended into urea grease (see Patent Document 1), and greases in which molybdenum disulfide, molybdenum dialkyldithiocarbamate, a calcium salt of petroleum sulfonic acid, a sulfur-based extreme pressure agent, a specific vegetable oil, and zinc dialkyldithiocarbamate are blended into urea grease (see Patent Document 2).

[0006] On the other hand, as greases having excellent wear resistance, there have been proposed greases in which benzotriazole and / or its derivatives and phosphates and / or their amine salts are blended into urea grease (see Patent Document 3), and greases in which stearic acid metal salts of Ca, Mg, Zn, etc., molybdenum dialkyldithiocarbamate, and zinc dialkyldithiocarbamate are blended into lithium soap grease (see Patent Document 4).

[0007] Thus, conventional CVJ grease compositions have been studied for durability and wear resistance at room temperature, but have not yet been sufficiently studied for durability and initial running-in properties at high temperatures.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2008-297402

[0011] Patent Document 2: Japanese Patent Application Publication No. 2010-90243

[0012] Patent Document 3: Japanese Patent Application Publication No. 2015-108067

[0013] Patent Document 4: Japanese Patent Application Publication No. 2011-79902 Summary of the invention

[0014] Problems to be solved by the invention

[0015] Therefore, an object of the present invention is to provide a grease composition having excellent durability and initial running-in properties even in a high-temperature environment.

[0016] Another object of the present invention is to provide a constant velocity joint in which the above-mentioned grease composition is sealed.

[0017] Methods for solving problems

[0018] The present inventors have conducted research and found that a grease composition using a base oil having a specific kinematic viscosity and viscosity index has excellent durability and initial running-in properties even at high temperatures. That is, according to the present invention, the following grease composition for a constant velocity joint and a constant velocity joint enclosed with the grease composition are provided.

[0019] 1. A grease composition for a constant velocity joint, comprising:

[0020] (a) Kinematic viscosity at 100°C is 16.0 mm 2 / s or more, and a base oil with a viscosity index of 90 or more,

[0021] (b) a diurea thickener represented by the following formula (1),

[0022] R 1 NH-CO-NH-C6H4-p-CH2-C6H4-p-NH-CO-NHR 1 ' (1)

[0023] In the formula, R 1 and R 1 'are independently octyl, dodecyl, hexadecyl, octadecyl or cyclohexyl,

[0024] (c) 0.2-2.0% by mass of zinc dialkyl dithiophosphate

[0025] (d) 0.5-2.0% by mass of oil-insoluble molybdenum dialkyl dithiocarbamate

[0026] (e) 0.5-3.0 mass % of oil-soluble molybdenum dialkyl dithiocarbamate

[0027] (f) 1.0 to 4.0 mass % of zinc dialkyldithiocarbamate, and

[0028] (g) 0.1-1.5% by mass of benzothiazolethione or its derivatives;

[0029] Furthermore, the mass ratio of component (f) to component (g) is (f):(g)=8:1-3:1.

[0030] 2. The grease composition according to item 1 above, wherein component (c) is represented by the following formula (2):

[0031] [(R 2 O)2SP-S]2-Zn (2)

[0032] In the formula, R 2 It is a primary or secondary alkyl group having 1 to 24 carbon atoms.

[0033] 3. The grease composition according to 1 or 2 above, wherein component (d) is represented by the following formula (3):

[0034] [R 30 2N-CS-S]2-Mo2O m S n (3)

[0035] In the formula, R 30 It is a primary or secondary alkyl group having 1 to 4 carbon atoms, m is 0 to 3, n is 1 to 4, and m+n=4.

[0036] 4. The grease composition according to any one of 1 to 3 above, wherein component (e) is represented by the following formula (4):

[0037] [R 31 2N-CS-S]2-Mo2O m S n (4)

[0038] In the formula, R 31 It is a primary or secondary alkyl group having 5 to 24 carbon atoms, m is 0 to 3, n is 1 to 4, and m+n=4.

[0039] 5. The grease composition according to any one of 1 to 4 above, wherein component (f) is represented by the following formula (5):

[0040] [R 4 2N-CS-S]2-Zn (5)

[0041] In the formula, R 4 It is a primary or secondary alkyl group having 1 to 24 carbon atoms.

[0042] 6. A constant velocity joint, wherein the grease composition for a constant velocity joint according to any one of 1 to 5 above is enclosed.

[0043] Effects of the Invention

[0044] The grease composition of the present invention is excellent in durability and initial running-in properties even in a high-temperature environment. The grease composition of the present invention is also excellent in shear stability. In addition, the grease composition of the present invention is also excellent in vibration resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 is a partially cutaway view of a tripod-type universal joint using the grease composition for a constant velocity joint of the present invention.

[0046] FIG. 2 is a partially cutaway view of a double offset joint using the constant velocity joint grease composition of the present invention. DETAILED DESCRIPTION

[0047] (a) Base oil

[0048] The kinematic viscosity of the base oil of the present invention at 100°C is 16.0 mm 2 / s or more, and the viscosity index is 90 or more.

[0049] By making the kinematic viscosity at 100°C 16.0 mm 2 / s or more, sufficient oil film thickness can be ensured even when the CVJ surface temperature is 90°C to 100°C, so lubricity can be maintained at high temperatures.

[0050] When the viscosity index is 90 or more, it is possible to achieve vibration suppression due to reduction in sliding resistance at room temperature and reduction in stirring resistance in a low-temperature environment.

[0051] As long as the kinematic viscosity and viscosity index are within such a range, the type of base oil used in the present invention is not particularly limited. For example, various synthetic oils such as mineral oils represented by cycloalkane series and paraffin series, synthetic hydrocarbon oils represented by polybutene, ether-based synthetic oils represented by alkyl diphenyl ether, silicone oils, and fluorinated oils can be cited. Synthetic oil can be a so-called biomass oil made from biological resources produced by animals and plants. For example, biomass ester oils synthesized from various fatty acids and alcohols using vegetable oils such as palm oil, corn oil, and soybean oil can also be used. The base oil can be used alone or mixed with two or more. From the viewpoint of cost, mineral oils are preferred, and from the viewpoint of viscosity index, paraffin-based mineral oils are preferred compared to cycloalkane series.

[0052] From the viewpoint of ensuring the oil film thickness at high temperature, the kinematic viscosity at 100°C is preferably 18.0 mm 2 In addition, from the viewpoint of vibration suppression at room temperature and reduction of stirring resistance in a low temperature environment, the kinematic viscosity at 100°C is preferably 24.0 mm 2 / s or less, more preferably 22.0 mm 2 / s or less.

[0053] From the viewpoint of vibration suppression at room temperature and reduction of stirring resistance in a low temperature environment, the viscosity index is preferably 93 or more. From the viewpoint of compatibility with the material of the boot, the viscosity index is preferably 120 or less, more preferably 110 or less.

[0054] The base oil of the present invention preferably has a kinematic viscosity of 18.0 mm / s at 100° C. from the viewpoint of ensuring the oil film thickness at high temperatures and reducing the sliding resistance at room temperature and reducing the stirring resistance at low temperatures. 2 / s or more and a mineral oil with a viscosity index of 95 or more. More preferably, the kinematic viscosity at 100°C is 19.0 to 20.0 mm 2 / s, mineral oil with a viscosity index of 95~105.

[0055] The kinematic viscosity of the base oil can be measured in accordance with JIS K 2283. The viscosity index of the base oil can be determined from the measured values ​​of the kinematic viscosity of the base oil at 40°C and 100°C using a calculation formula specified in JIS.

[0056] From the viewpoint of grease fluidity, the content of the base oil is preferably 80% to 94% by mass, more preferably 83% to 92% by mass, and even more preferably 85% to 90% by mass based on the total mass of the composition.

[0057] (b) Thickener

[0058] The thickener of the present invention is a diurea thickener represented by the following formula (1).

[0059] R 1 NH-CO-NH-C6H4-p-CH2-C6H4-p-NH-CO-NHR 1 ' (1)

[0060] In the formula, R 1 and R 1 ' are independently octyl, dodecyl, hexadecyl, octadecyl or cyclohexyl.

[0061] Examples of the diurea thickener of formula (1) include R 1 and R1 'Both are octyl, dodecyl, hexadecyl or octadecyl aliphatic diurea, containing R 1 and R 1 ' is an alicyclic aliphatic diurea compound in which any one of the diurea compounds is an octyl group, a dodecyl group, a hexadecyl group or an octadecyl group and the other is a cyclohexyl group; and R 1 and R 1 'Both are cyclohexyl alicyclic diureas.

[0062] Grease flows easily in the CVJ, so that grease is easily supplied to the sliding part, which improves durability. Therefore, the thickener is preferably an aliphatic diurea thickener or an alicyclic aliphatic diurea thickener that is easily softened by shear, and an alicyclic aliphatic diurea thickener is more preferred. As the aliphatic diurea thickener, R in formula (1) is preferably 1 and R 1 As the alicyclic aliphatic diurea thickener, R in formula (1) is preferably 1 and R 1 ' is a diurea compound in which one of the octadecyl group and the other is a cyclohexyl group, and R in formula (1) 1 and R 1 'Both are octadecyl diurea compounds and R in formula (1) 1 and R 1 'A mixture of diurea compounds containing both cyclohexyl groups. From the viewpoint of ensuring the fluidity of the grease, the molar ratio of the cyclohexyl group to the octadecyl group in the alicyclic aliphatic diurea thickener is preferably 1:9 to 3:7, and more preferably 1:9 to 2:8.

[0063] The content of the thickener may be an amount that can adjust the consistency of the grease to 300 to 350, and specifically, based on the total mass of the composition, is preferably 3 to 10% by mass, more preferably 4 to 9% by mass, and even more preferably 5 to 8% by mass. It should be noted that in this specification, "consistency" refers to the 60th work cone penetration measured by JIS K 2220.7.

[0064] As the (c) zinc dialkyldithiophosphate (ZnDTP), a substance represented by the following formula (2) is preferred.

[0065] [(R 2 O)2SP-S]2-Zn (2)

[0066] In the formula, R 2 It is a primary or secondary alkyl group having 1 to 24 carbon atoms or an aryl group having 6 to 30 carbon atoms, and is particularly preferably a primary or secondary alkyl group having 3 to 8 carbon atoms.

[0067] The content of component (c) is 0.2 to 2.0% by mass, preferably 0.5 to 1.8% by mass, and more preferably 0.8 to 1.5% by mass, based on the total mass of the composition. By containing component (c) in such a range, sufficient initial running-in properties can be obtained, which is preferred.

[0068] As the (d) oil-insoluble molybdenum dialkyldithiocarbamate (oil-insoluble MoDTC), a substance represented by the following formula (3) is preferred.

[0069] [R 30 2N-CS-S]2-Mo2O m S n (3)

[0070] In the formula, R 30 It is a primary or secondary alkyl group having 1 to 4 carbon atoms, preferably a primary or secondary alkyl group having 2 to 4 carbon atoms, m is 0 to 3, n is 1 to 4, and m+n=4.

[0071] From the viewpoint of low friction, the content of component (d) is 0.5 to 2.0% by mass, preferably 0.5 to 1.5% by mass, and more preferably 0.5 to 1.0% by mass, based on the total mass of the composition. By containing component (d) in such a range, sufficient low friction can be obtained, which is preferred.

[0072] As (e) the oil-soluble molybdenum dialkyldithiocarbamate (oil-soluble MoDTC), a substance represented by the following formula (4) is preferred.

[0073] [R 31 2N-CS-S]2-Mo2O m S n (4)

[0074] In the formula, R 31 It is a primary or secondary alkyl group having 5 to 24 carbon atoms, preferably a primary or secondary alkyl group having 5 to 18 carbon atoms, m is 0 to 3, n is 1 to 4, and m+n=4.

[0075] From the viewpoint of low friction, the content of component (e) is 0.5 to 3.0% by mass, preferably 0.5 to 2.5% by mass, and more preferably 0.5 to 2.0% by mass, based on the total mass of the composition. By containing component (e) in such a range, sufficient low friction can be obtained, which is preferred.

[0076] As the (f) zinc dialkyldithiocarbamate (ZnDTC), a substance represented by the following formula (5) is preferred.

[0077] [R 4 2N-CS-S]2-Zn (5)

[0078] In the formula, R 4 It is a primary or secondary alkyl group having 1 to 24 carbon atoms or an aryl group having 6 to 30 carbon atoms, and is preferably an alkyl group having 3 to 8 carbon atoms.

[0079] From the viewpoint of initial running-in, the content of component (f) is 1.0 to 4.0% by mass, preferably 1.2 to 3.8% by mass, and more preferably 1.5 to 3.5% by mass, based on the total mass of the composition. By containing component (f) in such a range, sufficient initial running-in can be obtained, which is preferred.

[0080] (g) Benzothiazolethione or its derivatives are generally used as extreme pressure agents for greases. For example, a compound represented by "Amines, C16-22-tert-alkyl, compds. with 2(3H)-benzothiazolethione (1:1)" (e.g. Vanlube (registered trademark) 601 manufactured by Vanderbilt) can be used, wherein a compound having a sulfur content of 5% to 20% by mass and a nitrogen content of 1% to 10% by mass is preferred.

[0081] From the viewpoint of initial running-in, the content of component (g) is 0.1 to 1.5% by mass, preferably 0.2 to 1.2% by mass, and more preferably 0.3 to 1.0% by mass, based on the total mass of the composition. By making the content of component (g) within such a range, sufficient initial running-in can be obtained, which is preferred.

[0082] The mass ratio of component (f) to component (g) is (f):(g)=8:1 to 3:1, preferably 6:1 to 3.5:1. The mass ratio of component (f) to component (g) within such a range is preferred because sufficient initial running-in properties can be obtained.

[0083] The grease composition of the present invention may contain, in addition to the above-mentioned components, other extreme pressure additives, antioxidants, rust inhibitors, and other additives commonly used in grease compositions. Examples of other extreme pressure additives include phosphate esters, etc. Examples of antioxidants include amines, phenols, etc. Examples of rust inhibitors include sulfonates, carboxylates, and amines. The content of such arbitrary additives is based on the total mass of the composition, for example, 0.1 to 2.0 mass %, preferably 0.3 to 1.0 mass %.

[0084] The grease composition for constant velocity joints of the present invention can be used in any constant velocity joints without limitation, but its effect is particularly pronounced in constant velocity joints in which internal parts perform rolling and sliding motions, such as telescopic constant velocity joints such as tripod-type joints and double offset-type joints.

[0085] As a preferred structure of the telescopic constant velocity universal joint according to the present embodiment, the following structures can be cited.

[0086] (A) A structure comprising an outer coupling member having three linear rolling grooves extending axially formed on the inner circumferential surface; a tripod member as an inner coupling member having three radially protruding foot shafts; and rollers as rolling bodies rotatably supported on the foot shafts of the tripod member, the rollers being arranged to roll freely along the rolling grooves of the outer coupling member.

[0087] (B) A structure comprising an outer coupling member, an inner coupling member, balls (3 to 8 in number) and a retaining frame; the outer coupling member has a plurality of linear raceway grooves extending axially formed on a cylindrical inner peripheral surface; the inner coupling member has a plurality of linear raceway grooves paired with the raceway grooves of the outer coupling member formed on a spherical outer peripheral surface; the balls are arranged as rolling elements between the raceway grooves of the outer coupling member and the raceway grooves of the inner coupling member; the retaining frame retains the balls between the outer coupling member and the inner coupling member.

[0088] The first and second specific embodiments of the constant velocity universal joint of the present invention are described based on Fig. 1 and Fig. 2. Fig. 1 shows a partial notch cross-sectional view of a tripod type universal joint (hereinafter, referred to as TJ), and Fig. 2 shows a partial notch cross-sectional view of a double offset type universal joint (hereinafter, referred to as DOJ). These are sliding type constant velocity universal joints used for automotive drive shafts (transmission shafts), etc.

[0089] As shown in FIG1 , TJ1 has three axial linear raceway grooves 3 formed on the inner surface of the outer coupling member 2. Three pins 5 are provided in the tripod member (inner coupling member) 4 assembled on the inner side of the outer coupling member 2. Spherical rollers 6 are inserted on the outer side of each pin 5, and needle rollers 7 are installed between the spherical rollers 6 and the pins 5 to support the spherical rollers 6 so that they can rotate and slide in the axial direction, and the spherical rollers 6 are inserted into the raceway grooves 3 so that they can roll freely. A protective cover 9 is installed from the outer coupling member 2 to the shaft 8 connected to the tripod member 4.

[0090] The protective cover 9 includes an outer cylinder end (large diameter mounting portion) 9a fitted and fixed to the outer coupling member 2, an inner cylinder end (small diameter mounting portion) 9b fitted and fixed to the shaft 8 connected to the inner coupling member 4, and a corrugated curved portion (hereinafter also referred to as a "corrugated portion") 9c, wherein the curved portion 9c has a plurality of valleys connecting the outer cylinder end 9a and the inner cylinder end 9b, and the protective cover 9 covers the constant velocity universal joint in a sealed manner. Grease is enclosed in the sealed space as a lubricant. The protective cover 9 fits the outer cylinder end 9a to the outer coupling member 2 and fixes it with a tightening band 10a or the like, and on the other hand, fixes the inner cylinder end 9b to the shaft 8 with a tightening band 10b or the like. A protective cover groove 8a is formed on the outer peripheral surface of the portion of the shaft 8 where the inner cylinder end 9b is fixed, and the inner cylinder end 9b is inserted into the protective cover groove 8a. It should be noted that by providing the annular protrusions 8 b on both sides of the shield groove 8 a , the inner tube end 9 b entering the shield groove 8 a can be more firmly fixed to the shaft 8 .

[0091] As shown in FIG2 , DOJ11 has a plurality of axially linear raceway grooves 14 and 15 formed on the inner surface of the outer coupling member 12 and the outer surface of the inner ring (inner coupling member) 13. The balls 16 assembled between the raceway grooves 14 and 15 are supported by a retainer 17, the outer periphery of which is a spherical surface 17a, and the inner periphery is a spherical surface 17b that fits the outer periphery of the inner ring 13. The centers (A) and (B) of the spherical surfaces 17a and 17b are axially offset on the axis of the outer coupling member 12. A protective cover 19 is installed from the outer coupling member 12 to the shaft 18 connected to the inner ring 13. The structure of the protective cover 19 and its installation structure are the same as those of the protective cover 9 in FIG1 . In addition, grease is enclosed in the space sealed by the protective cover 19 as a lubricant.

[0092] The constant velocity universal joint used for the automotive drive shaft (propeller shaft) enclosed with grease according to the present embodiment can maintain excellent durability at high temperatures.

[0093] Therefore, various constant velocity joints, particularly telescopic constant velocity joints, enclosing the above-mentioned grease composition also fall within the scope of the present invention.

[0094] Example

[0095] The following components were used to prepare the grease compositions of the examples and comparative examples. Specifically, 1 mol of 4',4-diphenylmethane diisocyanate was reacted with 2 mol of a specified amine in a base oil, and the mixture was heated, cooled, and kneaded with a three-roll mill to obtain a base grease. Additives were added thereto in the ratios shown in Table 1 (the numbers in the table are mass % based on the total mass of the composition), and base oil was further added in such a manner that the thickener amount was the ratio shown in Table 1, and the mixture was dispersed with a three-roll mill to obtain the grease compositions of the examples and comparative examples. It should be noted that the consistency was measured in accordance with JIS K2220 7. and was uniformly 325.

[0096] <(a) Base oil>

[0097] Mineral oil

[0098] <(b) Thickener>

[0099] Aliphatic diurea uses octylamine as the amine.

[0100] The alicyclic aliphatic diurea was used at a molar ratio of cyclohexylamine as amine to octadecylamine = 2:8.

[0101] The alicyclic aromatic diurea was used at a molar ratio of cyclohexylamine as amine to aniline = 7:3.

[0102] <Additives>

[0103] (c) ZnDTP: zinc dialkyl dithiophosphate (LUBRIZOL 1395, manufactured by Lubrizol)

[0104] (d) MoDTC (non-oil soluble): Molybdenum dialkyldithiocarbamate (ADEKA SAKURA-LUBE600, manufactured by ADEKA)

[0105] (e) MoDTC (oil-soluble): molybdenum dialkyldithiocarbamate (ADEKA SAKURA-LUBE525, manufactured by ADEKA)

[0106] (f) ZnDTC: zinc dialkyldithiocarbamate (Vanlube AZ, manufactured by Vanderbilt)

[0107] (g) Benzothiazolethione derivative (Vanlube 601, manufactured by Vanderbilt)

[0108] Test methods

[0109] The grease compositions of Examples and Comparative Examples were tested by the following methods.

[0110] <Roll Stability Test> (According to ASTM D1831)

[0111] This test is to evaluate the ease of softening of grease caused by shear.

[0112] ·Test Conditions

[0113] Atmosphere Temperature: 100 °C

[0114] Roll Rotation Speed: 165 rpm

[0115] Rotation Time: 24 h

[0116] ·Evaluation Criteria

[0117] Worked Cone Penetration of Grease after Test

[0118] 〇: 400 or more

[0119] ×: Less than 400

[0120] <SRV Test - Evaluation of Initial Running - in Performance> (According to ASTM D5706)

[0121] This test is to evaluate the degree of smoothing of the surface roughness of the plate after the test.

[0122] ·Test Conditions:

[0123] Surface Pressure: 2.8 GPa

[0124] Sliding Speed: 20 mm / s (3.0 mm × 3.3 Hz)

[0125] Plate Temperature: 95 °C

[0126] Ball Diameter: 17.5 mm

[0127] Surface Roughness Ra of Plate before Test: 0.7 μm

[0128] ·Evaluation Criteria

[0129] Surface Roughness Ra of Plate after Test

[0130] 〇: Less than 0.35 μm

[0131] ×: 0.35 μm or more

[0132] <Evaluation of Durability at High Temperature>

[0133] Seal each grease composition of the examples and comparative examples into an actual three - ball - pin type CVJ, and conduct a universal joint durability test under the following conditions to measure the occurrence time of spalling, thereby evaluating the durability at high temperature.

[0134] ·Test Conditions

[0135] Speed: 200rpm

[0136] Torque: 800Nm

[0137] Angle: 6°

[0138] Universal joint surface temperature: 90℃~100℃

[0139] Evaluation method

[0140] Disassemble and inspect the universal joint every 50 hours from the start of the test, and measure the peeling area of ​​the outer ring, inner ring, trunnion or needle roller to reach 20mm. 2 It should be noted that if the peeling area exceeds 20mm 2 , it will be difficult to continue operating afterwards.

[0141] Evaluation benchmark

[0142] 0:250h or more

[0143] ×: less than 250h

[0144] <Evaluation of Inductive Thrust-Vibration Resistance>

[0145] Each grease composition of the examples and comparative examples was sealed in an actual tripod-type CVJ, and the force generated in the axial direction when the CVJ was rotated by applying an operating angle and a torque was measured as the induced thrust to evaluate the vibration resistance.

[0146] ·Measurement conditions

[0147] Speed: 150rpm

[0148] Torque: 300Nm

[0149] Angle: 0~12 degrees

[0150] Evaluation benchmark

[0151] Induction thrust three components

[0152] 0:110Nrms or less

[0153] ×: more than 110Nrms

[0154] [Table 1]

[0155]

[0156] Description of Reference Numerals

[0157] 1: TJ, 2: outer coupling member, 3: raceway groove, 4: tripod member (inner coupling member), 5: foot shaft, 6: spherical roller, 7: needle roller, 8: shaft, 9: protective cover, 10a, 10b: tightening belt, 11: DOJ, 12: outer coupling member, 13: inner ring (inner coupling member), 14, 15: raceway groove, 16: ball, 17: cage, 18: shaft, 19: protective cover.

Claims

1. A grease composition for a constant velocity joint, comprising: (a) Kinematic viscosity at 100°C is 16.0 mm 2 / s or more, and a base oil with a viscosity index of 90 or more, (b) a diurea thickener represented by the following formula (1), R 1 NH-CO-NH-C6H4-p-CH2-C6H4-p-NH-CO-NHR 1 ' (1) In the formula, R 1 and R 1 'are independently octyl, dodecyl, hexadecyl, octadecyl or cyclohexyl, (c) 0.2-2.0% by mass of zinc dialkyl dithiophosphate (d) 0.5-2.0% by mass of oil-insoluble molybdenum dialkyl dithiocarbamate (e) 0.5-3.0 mass % of oil-soluble molybdenum dialkyl dithiocarbamate (f) 1.0 to 4.0 mass % of zinc dialkyldithiocarbamate, and (g) 0.1-1.5% by mass of benzothiazolethione or its derivatives; Furthermore, the mass ratio of component (f) to component (g) is (f):(g)=8:1-3:

1.

2. The grease composition according to claim 1, wherein Component (c) is represented by the following formula (2): [(R 2 O)2SP-S]2-Zn (2) In the formula, R 2 It is a primary or secondary alkyl group having 1 to 24 carbon atoms.

3. The grease composition according to claim 1, wherein Component (d) is represented by the following formula (3): [R 30 2N-CS-S]2-Mo2O m S n (3) In the formula, R 30 It is a primary or secondary alkyl group having 1 to 4 carbon atoms, m is 0 to 3, n is 1 to 4, and m+n=4.

4. The grease composition according to claim 1, wherein Component (e) is represented by the following formula (4): [R 31 2N-CS-S]2-Mo2O m S n (4) In the formula, R 31 It is a primary or secondary alkyl group having 5 to 24 carbon atoms, m is 0 to 3, n is 1 to 4, and m+n=4.

5. The grease composition according to claim 1, wherein Component (f) is represented by the following formula (5): [R 4 2N-CS-S]2-Zn (5) In the formula, R 4 It is a primary or secondary alkyl group having 1 to 24 carbon atoms. 6 . A constant velocity joint, wherein the grease composition for a constant velocity joint according to claim 1 is enclosed.

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