JP2008127404A - Roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller bearing for a constant-velocity joint port member or a center support member effectively preventing release caused by water penetration on a rolling surface and having an excellent long-term durability. <P>SOLUTION: The roller bearing is useful for a support number for rotatably supporting a drive shaft at a body side. The roller bearing 1 is equipped with an inner ring 2, an outer ring 3, a plurality of rolling elements 4 laid between the inner ring 2 and the outer ring 3, grease 7 sealed in the circumferences of the rolling elements 4 and sealing members 6 disposed at both end opening parts 8a and 8b in the axial directions of the inner ring 2 and the outer wheel 3 and sealing the grease 7. The grease 7 is waterproof grease obtained by mixing base grease composed of a nonaqueous base oil and a thickening agent with an additive containing at least a water dispersant. The amount of the water dispersant mixed is an amount to set the saturated water amount of the waterproof grease at 30-60 wt.%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rolling bearing used for a support member that supports a drive shaft of an automobile on the vehicle body side, and more particularly to a rolling bearing for a constant velocity joint support member and a center support member.

  In a motor vehicle, a drive shaft that transmits the driving force of an engine to each wheel is roughly classified into a propeller shaft and a drive shaft according to the transmission part. For automobiles, front engine / front drive vehicle (FF vehicle), front engine / rear drive vehicle (FR vehicle), four wheel drive vehicle (4WD vehicle), rear engine / rear drive vehicle (RR vehicle), etc. The propeller shaft is mainly used in FR vehicles and 4WD vehicles. FIG. 3 shows an outline of a drive shaft in a 4WD vehicle.

  As shown in FIG. 3, the propeller shaft 9 is a rotating shaft that transmits the driving force of the engine 12 from the transmission 10 to the final reduction gear 11. Consists of a constant velocity joint that can transmit rotation even if the axis crossing angle changes, and a spline and a tube that can expand and contract in the axial direction in order to respond to changes in the relative position of the transmission 10 and the final reduction gear 11. Has been. The propeller shaft 9 is basically a two-joint type, but depending on the structure and required performance of the vehicle, the shaft may be divided into a three-joint type and a four-joint type. A center support member 13 is used as means for supporting the shaft on the vehicle body side while allowing vibration of the propeller shaft.

  An example of the center support member 13 is shown in FIG. The center support member 13 has a cylindrical outer ring 15 disposed outside the cylindrical inner ring 14 at a predetermined interval, and a cross section is substantially between the outer ring 15 and the inner ring 14. A U-shaped elastic member 16 is arranged and configured. By attaching the inner ring 14 side of the center support member 13 configured as described above to the propeller shaft 9 side via the rolling bearing 1 and attaching the outer ring 15 side to the bracket on the vehicle body side, the propeller shaft 9 is attached. Anti-vibration support for rotation.

  On the other hand, as shown in FIG. 3, the drive shaft is a rotating shaft that transmits driving force from the transmission or the final reduction gear to the wheels, and is divided into a front drive shaft 17a and a rear drive shaft 17b. Since the front drive shaft 17a requires a large bending angle commensurate with wheel steering, a fixed constant velocity joint 18a having an allowable bending angle of about 40 ° or more is used for the wheel side joint. The transmission or the final deceleration side joint used in combination needs to absorb the movement of the suspension. For example, a sliding type constant velocity joint 18b that can expand and contract in the axial direction although the allowable angle is not large is used.

  In the case of a normal horizontal engine type, the drive shaft from the engine is unequal. Since unequal length shafts have different dynamic elasticity, handle operability is deteriorated. In order to prevent this, the intermediate drive shaft 17c is inserted as shown in FIG. 3, and the intermediate drive shaft 17c is supported on the vehicle body side near the constant velocity joint connecting portion by the constant velocity joint support member 19. FIG. 5 shows an enlarged partial sectional view in the vicinity of the constant velocity joint support member 19. As shown in FIG. 5, the constant velocity joint support member 19 rotatably supports an intermediate drive shaft 17 c connected to the constant velocity joint 18 on the vehicle body side via the rolling bearing 1.

  Urea grease is mainly used for lubrication of the rolling bearing for the constant velocity joint support member or the center support member. Fluorine grease is used when the temperature conditions are more severe, but fluorine grease is extremely expensive, and as a method to achieve the equivalent performance more economically, specific urea grease and fluorine grease are mixed. There is something. On the other hand, when such temperature conditions are severe, the rolling bearing seal member is also required to have heat resistance. Conventionally, an acrylic rubber having relatively high heat resistance and excellent oil resistance has been used as the elastic body of the seal member.

  The bearings for these constant velocity joint support members or center support members may have an exhaust pipe disposed around them due to the design of the vehicle. In such a case, the ambient temperature of the bearing becomes high and acrylic rubber is heat resistant. There is a problem that sex is not enough. As a solution to this problem, it is conceivable to use fluororubber, which has better heat resistance than acrylic rubber. However, as described above, urea-based grease is mainly used for lubrication of the rolling bearing. In combination with the system grease, there is a problem that the cross-linking of the fluororubber proceeds and hardens due to the urea compound. When the rubber elastic body used for the seal member is cured, the sealing performance is deteriorated, which causes grease leakage and a problem of shortening the bearing life. In addition, the contact pressure at the seal surface is increased, and the rotational torque of the bearing is increased. As a result, frictional heat is generated, and the grease is further deteriorated.

  To solve this problem, grease containing a urea compound is used as a rolling bearing for constant velocity joint support members and center support members, and a rubber molding that contacts at least the grease is used as a seal member for sealing the grease. The rubber molded body contains tetrafluoroethylene, propylene, and a crosslinking monomer composed of an unsaturated hydrocarbon having 2 to 4 carbon atoms in which a part of hydrogen atoms are substituted with fluorine atoms. There is known a rolling bearing using a vulcanizable fluoro rubber composition formed of a copolymer (see Patent Document 1).

On the other hand, these bearings are arranged at the lower part of the automobile and below the vehicle body, and the water infiltrates due to rain water and the puddle of the puddle. Further, when traveling in a region with a lot of snowfall, the snow adhering to the lower part of the vehicle body melts while the vehicle is stopped, and the melted snow may enter the bearing. As described above, each bearing is provided with a seal to prevent intrusion of dust from outside and leakage of grease, but it is difficult to completely prevent water from entering. Particularly in recent years, due to demands for low fuel consumption, there is a tendency to reduce the tightening force of the seal in order to reduce the rotational torque, making it easy for water to enter.
When water enters the bearing, the following problems arise. When water droplets enter the load area, the oil film is interrupted, which is disadvantageous in terms of lubricity. When the oil film is interrupted, metal contact occurs, and there is a risk that wear, surface-origination type peeling, and early peeling occur on the rolling surface of the bearing. Early peeling refers to peeling accompanied by a white texture change that occurs in the vicinity of the surface, or peeling in which a crack propagates in the vicinity of the surface in the direction opposite to the rolling direction of the rolling element. In addition, rust is generated inside the bearing depending on the state of water in the bearing.
JP 2006-29346 A

  The present invention has been made to cope with such a problem, and in a rolling bearing used for a constant velocity joint support member or a center support member, the separation at the rolling surface due to water intrusion is effective. An object of the present invention is to provide a rolling bearing that can be prevented for a long time and has excellent long-term durability.

  The rolling bearing of the present invention is a rolling bearing used as a support member that rotatably supports a drive shaft on the vehicle body side. The rolling bearing includes an inner ring and an outer ring, and a plurality of rolling rings interposed between the inner ring and the outer ring. A moving body, grease sealed around the rolling element, and a seal member provided at both ends of the inner ring and the outer ring in the axial direction for sealing the grease. A water-resistant grease in which an additive containing at least a water dispersant is blended with a base grease composed of oil and a thickener, and the water dispersant has a saturated water content of 30 to 60% by weight. The amount is set.

The support member is a constant velocity joint support member that supports a drive shaft of a front engine / front drive vehicle, a rear engine / rear drive vehicle, or a four-wheel drive vehicle.
The support member may be a center support member that supports a propeller shaft of a front engine / rear drive vehicle or a four-wheel drive vehicle.

The water dispersant is a surfactant.
The non-aqueous base oil is characterized by comprising at least one oil selected from mineral oil, poly-α-olefin oil and alkyl diphenyl ether oil.
The thickening agent is a urea compound.

In the rolling bearing of the present invention, the water-resistant grease enclosed in the bearing is a base grease composed of a non-aqueous base oil and a thickener, and a water dispersant capable of dispersing water as fine particles in the grease. Since it is blended, the water that has entered the bearing can be dispersed as fine particles. Therefore, even if water is mixed in the water-resistant grease of this bearing, it is possible to suppress the action of moisture that inhibits oil film formation. As a result, metal contact on the rolling surface is suppressed, early peeling can be prevented, and constant velocity joint support that requires long-term durability under conditions where water enters due to splashing rainwater or puddles. It can be suitably used as a rolling bearing used for a member or a center support member.
Regarding the rust prevention action, the contact between the steel constituting the bearing and the massive water component can be reduced, so that the generation of rust can be suppressed.

  Moisture that can disperse water as fine particles in grease as a result of intensive investigations on rolling bearings used for constant velocity joint support members or center support members that can prevent premature damage when water enters. It has been found that a bearing filled with water-resistant grease whose saturation moisture content is controlled by blending a powder lasts without deterioration of the lubrication performance of the rolling contact portion even when water enters. This is because the water-resistant grease with controlled saturation moisture content breaks down the oil film formed by the grease because the infiltrated water becomes fine water particles that are uniformly dispersed in the water-resistant grease and trapped in the continuous phase grease. Therefore, it is considered that the durability of the rolling bearing is improved. The present invention is based on such knowledge.

上記各部材は、車両の設計上、排気管がその周囲に配置される場合があり、その場合においては軸受の周囲温度が 150℃ 以上の高温となる。 The rolling bearing of the present invention used for the constant velocity joint support member or the center support member is a bearing that supports the drive shaft, and is provided at the position shown in FIG. 3 as described above. Table 1 shows a comparison of each support site, rotation speed, support method, and ambient temperature.

In each of the above members, the exhaust pipe may be disposed around the member due to the design of the vehicle. In that case, the ambient temperature of the bearing becomes a high temperature of 150 ° C. or higher.

An example of the rolling bearing of the present invention is shown in FIG. FIG. 1 is a cross-sectional view of a deep groove ball bearing in which water-resistant grease is sealed.
In the deep groove ball bearing 1, an inner ring 2 having an inner ring rolling surface 2a on an outer peripheral surface and an outer ring 3 having an outer ring rolling surface 3a on an inner peripheral surface are arranged concentrically, and the inner ring rolling surface 2a and the outer ring rolling surface 3a are arranged. A plurality of rolling elements 4 are arranged between the two. Sealers 6 that are fixed to the cage 5, the outer ring 3, and the like that hold the plurality of rolling elements 4 are provided in the axially opposite end openings 8a, 8b of the inner ring 2 and the outer ring 3, respectively. A water-resistant grease 7 described later is enclosed at least around the rolling element 4.

The seal member 6 may be a rubber molded body such as a fluororubber composition alone, or may be a composite of a rubber molded body and a metal plate, a plastic plate, a ceramic plate, or the like. From the viewpoint of durability and ease of fixing, a composite of a rubber molded body and a metal plate is preferable.
An example of the sealing member 6 made of a composite of a rubber molded body and a metal plate is shown in FIG. The seal member 6 is obtained by fixing a fluororubber molded body 6b to a metal plate 6a such as a steel plate. The fixing method may be either mechanical fixing or chemical fixing. As a preferable fixing method, there can be mentioned a method in which a metal plate is placed in a vulcanizing mold, and molding and vulcanization are performed and fixed at the time of vulcanization of a fluororubber molded article.

  The seal member 6 can be mounted by (1) fixing one end 6c of the seal member 6 to the outer ring 3, and forming the labyrinth gap along the V groove on the seal surface of the inner ring 2 at the other end 6d. One end 6c of the member 6 is fixed to the outer ring 3, and the other end 6d is brought into contact with the V groove side surface of the seal surface of the inner ring 2. (3) One end 6c of the seal member 6 is fixed to the outer ring 3, and the other end 6d is the inner ring. 2 is contacted with the side surface of the V-groove of the sealing surface, but a low-torque structure is provided by providing a suction-preventing slit or the like in the contacting lip.

The water resistant grease used in the present invention is a water resistant grease obtained by blending an additive containing a water dispersing agent capable of dispersing water into a base grease composed of a non-aqueous base oil and a thickener, and enters a bearing. It has a certain affinity for incoming water. A numerical value indicating this affinity was called “saturated water content” and defined as the following formula.

Saturated water content (wt%) = maximum water content dispersible in grease x 100 / (grease weight + maximum water content dispersible in grease)

In the water resistant grease used in the present invention, the blending amount of the water dispersant is such an amount that the saturated moisture content of the grease represented by the above formula can be made 30 to 60% by weight, preferably 40 to 50% by weight. Within this range, inhibition of oil film formation due to moisture can be suppressed.
If the amount of the water dispersant is less than 30% by weight, it becomes difficult for water to be taken in, and the infiltrated water exists as large water droplets inside the bearing and inhibits oil film formation. On the other hand, if the blending amount is more than 60% by weight, a large amount of moisture is retained inside the bearing, and rust is generated.

  In addition, the amount of the water dispersant should be such that the particle size of the water dispersed by the water dispersant measured at a water content of 20% by weight is 50 μm or less with respect to the total amount of grease and the total amount of water. Is preferred. If the water droplets are 50 μm or less, the water does not inhibit the formation of the oil film by the water resistant grease. Preferably it is 30 micrometers or less, More preferably, it is the range of 5-25 micrometers. If it exceeds 50 μm, oil film formation is inhibited and the bearing life is extremely shortened. The water particle diameter in the present invention is a numerical value obtained by measuring the diameter of water droplets dispersed in a base grease having a water content of 20% by weight spread on a glass plate under a load of 600 N with a microscope. .

In the present invention, a surfactant can be used as the water dispersant capable of controlling the saturated water content. Surfactant makes water harmless by dispersing water in grease to prevent oil film breakage and rusting even when water enters a rolling bearing used for constant velocity joint support members or center support members. Used to make The water that has entered the grease is dispersed in the grease as fine water particles by the surfactant. Since grease can exist as a continuous phase, it is thought that oil film breakage does not occur.
Similarly, water particles, which are discontinuous phases confined in grease, which is a continuous phase, have a very low probability of coming into contact with the steel constituting the rolling bearing body used for constant velocity joint support members or center support members. The water particles adhering to the steel with probability are immediately replaced with the continuous phase grease by the rotation of the rolling elements linked to the rotation of the rolling bearing body used for the constant velocity joint support member or center support member. It is thought that it cannot rust.

  The surfactant that can be used in the present invention is a W / O (water phase dispersed in an oil phase (grease)) type interface that easily traps water particles as a discontinuous phase in a grease that is a continuous phase. The HLB (Hydrophilic-Lipophilic Balance) value representing the degree of affinity of the surfactant for water and oil is preferably in the range of 5-18.

  Specific examples of the surfactant used in the present invention include glycol surfactants such as polyalkylene glycols, carboxylic acid alkylene glycols, and carboxylic acid polyalkylene glycols, glycerin glycerin, and polyoxyalkyl carboxylates. Glycerin surfactants such as glycerin and glyceryl carboxylates, glyceryl surfactants such as polyglyceryl carboxylates and polyoxyalkylene glyceryl carboxylates, polyoxyalkylene alkyl ethers, and polyoxyalkylene alkyl ether carboxylates Ether surfactants such as carboxylic acid polyoxyalkylene alkyl ether diesters and sorbitan ester surfactants, polyoxyalkylene hardened castor oil, carboxylic acid polyoxyal Castor oil surfactants such as alkylene hydrogenated castor oil-based, carboxylic acid polyoxyalkylene Rent trimethylolpropane-based surfactant, metal sulfonate surfactant, sorbitan ester surfactant and the like. These surfactants may be used alone or in combination of two or more.

In the present invention, among the above surfactants, it is preferable to use a metal sulfonate surfactant, a carboxylic acid polyalkylene glycol surfactant, or a sorbitan ester surfactant. Particularly preferred are Ca sulfonate, polyethylene glycol stearate, sorbitan monooleate and the like.
The metal sulfonate surfactant, carboxylic acid polyalkylene glycol surfactant, or sorbitan ester surfactant can control the saturated water content within the range of 30 to 60% by weight within the range of the following blending amount. it can.

  The amount of the surfactant (aqueous dispersant) that can be used in the present invention is such an amount that the saturated water content of the grease can be adjusted to 30 to 60% by weight as described above. Specifically, it is increased with the non-aqueous base oil. The amount is preferably 0.4 to 4 parts by weight with respect to 100 parts by weight of the base grease comprising the agent. More preferably, it is 1 to 4 parts by weight. If the amount is less than 0.4 parts by weight, the saturated water content may not be 30% by weight or more, and it is difficult to obtain the desired effect sufficiently. If the amount exceeds 4 parts by weight, the saturated water content may exceed 60% by weight, and the desired effect such as oil film formation rate will reach its peak, reducing the grease characteristics such as bearing life.

The Ca sulfonate that can be used in the present invention preferably has a base number in the range of 50 to 500. A base number shows the quantity of the basic substance contained in 1 molecule, and becomes a high numerical value, when there is much quantity of Ca which an additive contains. Basic Ca sulfonate can not only provide rust prevention performance but also extreme pressure performance.
For example, in the present invention, when 0.5 to 2 parts by weight of Ca sulfonate is blended with 100 parts by weight of the base grease, the extreme pressure performance becomes insufficient when the base number is less than 50, and the base number exceeds 500. No further effect can be expected.

  The sorbitan monooleate that can be used in the present invention is a nonionic surfactant, has an HLB value of about 9 indicating the degree of affinity of the surfactant with water and oil, and has lipophilic properties. Have The sorbitan monooleate is preferably used in combination with the Ca sulfonate.

In the present invention, the combination amount of Ca sulfonate and sorbitan monooleate as the surfactant is 0.5 to 2 parts by weight of Ca sulfonate and 0.2 to 1 part by weight of sorbitan monooleate with respect to 100 parts by weight of the base grease. Part.
Moreover, when using these independently, it is preferable to mix | blend Ca sulfonate 1.5-4 weight part and sorbitan monooleate 0.4-2 weight part.
By using both in the above range, the saturated moisture content of the water-resistant grease can be controlled to 30 to 60% by weight. In addition, the desired effect such as the oil film formation rate has reached its peak, and there is no fear that the grease characteristics such as the bearing life will deteriorate.

Non-aqueous base oils that can be used in the present invention are mineral oils such as spindle oil, refrigerator oil, turbine oil, machine oil, dynamo oil, highly refined mineral oil, liquid paraffin oil, GTL oil synthesized by Fischer-Tropsch method, polybutene oil , Poly-α-olefin (hereinafter referred to as “PAO”) oil, alkylnaphthalene oil, hydrocarbon synthetic oil such as alicyclic compound, or natural oil, polyol ester oil, phosphate ester oil, polymer ester oil, aromatic Non-hydrocarbon synthetic oils such as group ester oil, carbonate ester oil, diester oil, polyglycol oil, silicone oil, polyphenyl ether oil, alkyl diphenyl ether oil, alkylbenzene oil, and fluorinated oil can be used. These non-aqueous base oils can be used alone or in combination of two or more.
In consideration of lubricating performance and price, among these non-aqueous base oils, it is preferable to use mineral oil, PAO oil, or alkyl diphenyl ether oil.

The non-aqueous base oil that can be used in the present invention is liquid at room temperature and has a kinematic viscosity at 40 ° C. of ²⁰ to 200 mm ² / sec. Preferably, it is 30-120 mm < ² > / sec. If it is less than 20 mm ² / sec, the non-aqueous base oil deteriorates in a short time, and the produced degradation product promotes the deterioration of the entire non-aqueous base oil, so the durability of the bearing is reduced and the life is shortened. On the other hand, if it exceeds 200 mm ² / sec, the temperature rise of the bearing due to the increase of the rotational torque becomes large.

In the present invention, the blending ratio of the non-aqueous base oil in 100 parts by weight of the base grease is preferably 60 to 99 parts by weight, more preferably 70 to 95 parts by weight.
When the blending ratio of the non-aqueous base oil is less than 60 parts by weight, the grease is hard and the lubricity at low temperatures is poor. If it exceeds 99 parts by weight, it will be soft and leaky.

  Thickeners that can be used in the water-resistant grease in the present invention include benton, silica gel, fluorine compound, lithium soap, lithium complex soap, strong lucium soap, calcium complex soap, aluminum soap, aluminum complex soap and other soaps, diurea compounds, Examples include urea compounds such as polyurea compounds. In consideration of heat resistance, cost, and the like, a urea compound is desirable.

式中においてＲ² は、炭素原子数 6〜15 の芳香族炭化水素基を、Ｒ¹ およびＲ³ は、互いに同一であっても異なっていてもよく、それぞれ炭素原子数 6〜12 の芳香族炭化水素基または炭素原子数 6〜20 の脂環族炭化水素基およびまたは炭素原子数 6〜20 の脂肪族炭化水素基から選ばれた少なくとも一つの基を、それぞれ示す。
ウレア系化合物は、イソシアネート化合物とアミン化合物とを反応させることにより得られる。反応性のある遊離基を残さないため、イソシアネート化合物のイソシアネート基とアミン化合物のアミノ基とは略当量となるように配合することが好ましい。 The urea compound is represented, for example, by the following formula (1).

In the formula, R ² is an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R ¹ and R ³ may be the same or different from each other, and each of them is an aromatic group having 6 to 12 carbon atoms. At least one group selected from a hydrocarbon group or an alicyclic hydrocarbon group having 6 to 20 carbon atoms and / or an aliphatic hydrocarbon group having 6 to 20 carbon atoms is shown.
A urea compound is obtained by reacting an isocyanate compound and an amine compound. In order not to leave a reactive free radical, the isocyanate group of the isocyanate compound and the amino group of the amine compound are preferably blended so as to be approximately equivalent.

The diurea compound represented by the formula (1) can be obtained, for example, by reaction of diisocyanate and monoamine. Diisocyanates include phenylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 2,4-tolylene diisocyanate, 3,3-dimethyl-4,4-biphenylene diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate. Examples of the monoamine include octylamine, dodecylamine, hexadecylamine, stearylamine, oleylamine, aniline, p-toluidine, cyclohexylamine and the like.
In the present invention, an alicyclic-aromatic urea compound or an aromatic urea compound obtained by a reaction of an aromatic diisocyanate with an alicyclic monoamine and an aromatic monoamine, or an aromatic monoamine alone is preferable. Particularly preferably, cyclohexylamine is used as the alicyclic monoamine and aniline is used as the aromatic monoamine.

For example, after sufficiently reacting monoamine acid and diisocyanate in a non-aqueous base oil at about 70 to 120 ° C., the temperature is raised and maintained at 120 to 180 ° C. for about 1 to 2 hours, and then cooled. , Homogenizers, three roll mills, etc. are used to obtain a base grease for blending various compounding agents.
In the present invention, the blending ratio of the thickener in 100 parts by weight of the base grease is preferably 1 to 40 parts by weight, more preferably 3 to 25 parts by weight. If the blending ratio of the thickener is less than 1 part by weight, the thickening effect will be reduced and it will be difficult to make grease, and if it exceeds 40 parts by weight, the grease will be too hard and the desired effect will not be obtained.

  To the water-resistant grease used in the present invention, known additives other than the above-mentioned surfactant (water dispersing agent) can be added as necessary within the range not impairing the function. Examples of additives include extreme pressure agents such as organic zinc compounds and organic molybdenum compounds, antioxidants such as amine-based, phenol-based and sulfur-based compounds, anti-wear agents such as sulfur-based and phosphorus-based compounds, and polyhydric alcohols. Examples thereof include rust preventives such as esters, viscosity index improvers such as polymethacrylate and polystyrene, solid lubricants such as molybdenum disulfide and graphite, and oily agents such as esters and alcohols. Moreover, metal fine powders, such as molybdate, an organic acid salt, aluminum, and copper, can also be mix | blended as an additive which suppresses early peeling with a white structure | tissue change. These can be added alone or in combination of two or more.

  Among the above additives, the water resistant grease used in the present invention preferably contains an extreme pressure agent for imparting extreme pressure performance and an antioxidant for suppressing oxidative degradation. It is particularly preferable to use zinc dithiophosphate as the extreme pressure agent and an amine antioxidant as the antioxidant.

式中においてＲ は、アルキル基を示す。アルキル基としては、一級アルキル基、二級アルキル基およびアリール基が挙げられるが、水に対する安定性や摩耗防止性等のバランスのよい二級アルキル基を用いることが好ましい。 Examples of zinc dithiophosphate include zinc dialkyldithiophosphate represented by the following formula (2), which is added to impart extreme pressure performance of grease.

In the formula, R 1 represents an alkyl group. Examples of the alkyl group include a primary alkyl group, a secondary alkyl group, and an aryl group, but it is preferable to use a secondary alkyl group having a good balance such as stability against water and wear resistance.

  The compounding amount of zinc dithiophosphate is preferably 0.5 to 2.0 parts by weight based on 100 parts by weight of the base grease. Most preferably, it is 2.0 parts by weight with respect to 100 parts by weight of the base grease. If the amount is less than 0.5 parts by weight, the extreme pressure performance becomes insufficient, and it is difficult to obtain the desired effect sufficiently, and even if added over 2.0 parts by weight, no further effect can be obtained. Can not.

Examples of amine antioxidants include phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, and 3,7-dioctylphenothiazine. , P, p′-dioctyldiphenylamine, N, N′-diisopropyl-p-phenylenediamine, and the like.
The compounding amount of the amine antioxidant is preferably 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the base grease. When the amount is less than 0.5 parts by weight, the antioxidant performance becomes insufficient, and it becomes difficult to obtain the desired effect sufficiently, and even if added over 2.0 parts by weight, no further effect can be expected. Most preferably, it is 1 part by weight per 100 parts by weight of the base grease.

The present invention will be specifically described with reference to examples and comparative examples, but is not limited to these examples.
Example 1 to Example 5, Example 8 to Example 13, and Comparative Example 1 to Comparative Example 6
A mineral oil / urea base grease (JIS consistency No. 2 grade, consistency: 265 to 295) in which a urea compound is uniformly dispersed as a thickener in a mineral oil which is a non-aqueous base oil was prepared.
In 2000 g of mineral oil (Nippon Petroleum Turbine 100, kinematic viscosity at 40 ° C .: 100 mm ² / sec), 2000 g of diphenylmethane-4,4′-diisocyanate, 86.2 g of aniline and 91.7 g of cyclohexylamine And the resulting urea compound was uniformly dispersed to obtain a base grease. Additives were added to the base grease in the formulation shown in Table 2 to obtain a test grease.

  The obtained grease for testing was subjected to an oil film formation rate test, a bearing life test, and a saturated water content measurement described below, and an oil film formation rate, a bearing life time, a saturated water content, and whether or not rust was generated were measured. The results are also shown in Table 2.

<Oil film formation rate test>
Bearing used: Angular contact ball bearing 7006ADLLB (outer ring S53C, inner ring SUJ2) was used.
Test conditions: 1.0 g of the obtained grease for test is sealed in an angular ball bearing 7006ADLLB and rotated at a radial load of 8000 N, an axial load of 3000 N, and a bearing rotational speed of 1000 rpm. The oil film formation rate of the test grease when water was poured for 10 hours was measured. The oil film formation rate was measured by the electric resistance method.

<Bearing life test>
Bearing used: Angular contact ball bearing 7006ADLLB (outer ring S53C, inner ring SUJ2) was used.
Test conditions: 1.0 g of the obtained grease for test is sealed in an angular ball bearing 7006ADLLB, and is rotated at a radial load of 8000 N, an axial load of 3000 N, and a bearing rotational speed of 1000 rpm. The bearing life when water was poured was measured. The bearing life was defined as the time until one of the outer ring rolling surface, the inner ring rolling surface, and the steel ball peeled and the vibration increased.

<Saturated water content measurement>
Add a fixed amount of water to the test grease by changing the mixing ratio of water by 5% by weight, and manually stir using a microspatel to obtain the maximum amount of water that could disperse the added water. The saturated water content was calculated using the formula. To determine whether it was dispersed, collect test grease on a glass plate, place a spacer shim with a thickness of 0.025 mm on both ends of the glass plate, and sandwich it with another glass plate from above. When the test grease was spread and observed with a microscope, the largest water droplets present in the grease were considered to be dispersed when the particle size was 50 μm or less.

Saturated water content (wt%) = maximum water content dispersible in grease x 100 / (weight of test grease + maximum water content dispersible in grease)

Example 6
In a reaction vessel, 11.7 g of PAO oil (Nippon Chemical Co., Ltd., Sinfluid 801: Kinematic viscosity at 40 ° C .: 46 mm ² / sec), 231.7 g of diphenylmethane-4,4′-diisocyanate and 86.2 g of aniline And 91.7 g of cyclohexylamine were reacted to uniformly disperse the produced urea compound to obtain a base grease. Additives were added to the base grease in the formulation shown in Table 1 to obtain a test grease. The same items as in Example 1 were measured for the obtained test grease. The results are also shown in Table 2.

Example 7
In a reaction vessel, 231.7 g of diphenylmethane-4,4'-diisocyanate and 86.2 g of aniline in 1850 g of alkyl diphenyl ether oil (LB100, Matsumura Oil Co., Ltd., kinematic viscosity at 40 ° C .: 100 mm ² / sec) Then, 91.7 g of cyclohexylamine was reacted, and the resulting urea compound was uniformly dispersed to obtain a base grease. Additives were added to the base grease in the formulation shown in Table 1 to obtain a test grease. The same items as in Example 1 were measured for the obtained test grease. The results are also shown in Table 2.

As shown in Table 2, a high oil film formation rate is obtained in a region where the saturated water content is 30 to 60% by weight (particularly 40 to 50% by weight).
When water is mixed in, grease with saturated water content of less than 30% by weight or grease with more than 60% by weight impairs the formation of an oil film, which causes metal contact and rust. When the saturated water content is 30 to 60% by weight, an oil film can be formed, so there is little risk of metal contact, so the bearing life is long and the occurrence of rust can be suppressed.

  The rolling bearing according to the present invention includes a base grease composed of a non-aqueous base oil and a thickener and a water dispersant capable of dispersing water in the grease so that the saturated water content of the grease is 30 to 60 weights. % Water-resistant grease is enclosed, so even if water enters the grease during operation, it can suppress the action of moisture that inhibits the formation of an oil film on the grease, and prevents early peeling of the bearing. Even if the lubrication conditions become severe, a long life can be obtained. Therefore, it can be suitably used as a bearing used for a constant velocity joint port member or a center support member that is required to have long-term durability as well as wear resistance in an environment where there is a possibility of water intrusion.

It is sectional drawing of a deep groove ball bearing. It is sectional drawing of the sealing member of a rolling bearing. It is the schematic of the drive shaft in a 4WD vehicle. It is sectional drawing of a center support member. It is sectional drawing of a constant velocity joint support member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Deep groove ball bearing 2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Seal member 7 Water resistant grease 8a, 8b Opening 9 Propeller shaft 10 Transmission 11 Final reduction device 12 Engine 13 Center support member 14 Inner ring 15 Outer ring 16 Elastic member 17 Drive shaft 18 Constant velocity joint 19 Constant velocity joint support member

Claims (6)

A rolling bearing used as a support member that rotatably supports a drive shaft on the vehicle body side, the rolling bearing comprising an inner ring and an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and the rolling elements Grease provided around, and a seal member that is provided at both ends of the inner ring and the outer ring in the axial direction and seals the grease;
The grease is a water-resistant grease in which an additive containing at least a water dispersant is blended with a base grease composed of a non-aqueous base oil and a thickener, and the amount of the water dispersant is equal to the saturated moisture content of the water-resistant grease. A rolling bearing characterized in that the amount is set to 30 to 60% by weight.   The rolling bearing according to claim 1, wherein the support member is a constant velocity joint support member that supports a drive shaft of a front engine / front drive vehicle, a rear engine / rear drive vehicle, or a four-wheel drive vehicle.   The rolling bearing according to claim 1, wherein the support member is a center support member that supports a propeller shaft of a front engine / rear drive vehicle or a four-wheel drive vehicle.   The rolling bearing according to claim 1, wherein the water dispersant is a surfactant.   The rolling bearing according to any one of claims 1 to 4, wherein the non-aqueous base oil comprises at least one oil selected from mineral oil, poly-α-olefin oil, and alkyl diphenyl ether oil.   The rolling bearing according to any one of claims 1 to 5, wherein the thickener is a urea compound.

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