JP4751806B2 - Rolling bearings for automotive electrical equipment and accessories - Google Patents

Description

  The present invention relates to a rolling bearing for automobile electrical equipment / auxiliary machinery, and more particularly to automotive electrical components such as alternators, idler pulleys, electromagnetic clutches for car air conditioners, electric fan motors, and rolling bearings for auxiliary machinery.

In recent years, along with demands for miniaturization, weight reduction and quietness improvement of automobiles, miniaturization, weight reduction and sealing of engine compartments have been attempted for the electrical parts and auxiliary parts. The demand for high output and high efficiency is increasing in the performance of the engine itself, and in the electrical equipment and auxiliary equipment in the engine room, a method of compensating for the decrease in output caused by downsizing by rotating at high speed is adopted. Yes.
Hereinafter, outlines of a rolling bearing for an alternator for an automobile and a rolling bearing for an idler pulley will be described as examples of the rolling bearing for an automobile electrical equipment / auxiliary machine.

The alternator for automobiles has a function of generating power by receiving rotation of an engine with a belt, supplying electric power to an electric load of the vehicle, and charging a battery. For this reason, rolling bearings for alternators are required to have heat resistance, grease sealability, and durability that can withstand extremely harsh environments such as high-speed rotations of 10,000 rpm or higher at high temperatures of 180 ° C or higher.
By adopting a terpolymer of vinylidene fluoride-tetrafluoroethylene-propylene or a tetrafluoroethylene-propylene binary copolymer as an elastic body of a seal member that requires heat resistance and durability, In this combination, a method for improving the durability of the rolling bearing is known (see Patent Document 1).

  Further, as a rolling bearing used in an alternator or the like, grease containing a urea compound is used, and a seal member for sealing the grease has at least a rubber molded body that comes into contact with the grease. A vulcanizable fluororubber comprising a copolymer comprising fluoroethylene, propylene, and a crosslinking monomer comprising an unsaturated hydrocarbon having 2 to 4 carbon atoms in which some of the hydrogen atoms are substituted with fluorine atoms A rolling bearing using a molded body of the composition is known (see Patent Document 2 and Patent Document 3).

The idler pulley for automobiles is used as a belt tensioner for a drive belt that transmits engine rotation to the auxiliary equipment of the automobile, and is used to apply tension as a tensioner to the belt when the center distance is fixed. The function as a pulley is combined with the function as an idler that is used to change the running direction of the belt or to avoid an obstacle to reduce the volume of the engine compartment. For this reason, idler pulley rolling bearings are required to have heat resistance, grease sealability, and durability that can withstand extremely harsh environments such as high-speed rotation of 10,000 rpm or higher at a high temperature of 180 ° C or higher.
As a grease composition suitable for rolling bearings used at high temperature and high speed, an amide wax having a melting point of 80 ° C or higher, which has an antioxidant ability for base oil, is blended in the grease composition at 0.5 to 10% by weight, and 40 ° C. Grease formulated with a base oil with a kinematic viscosity of 20 to 150 mm ² / sec and a thickener of the grease composition is a urea thickener, and 5 to 30% by weight based on the total grease composition A composition is known (see Patent Document 4).

These bearings are arranged in the engine room. The engine room is not completely sealed for reasons such as cooling, and water can enter due to rain water and water pool splashing. 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 the demand for low fuel consumption, there is a tendency to reduce the tightening force of the seal in order to reduce the rotational torque, which makes 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. Premature peeling refers to peeling accompanied by a white structure change near the surface, or peeling in which cracks develop near 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 2001-65578 A JP 2005-226830 A JP 2005-256891 A JP 2003-105366 A

  The present invention has been made to cope with such problems, and can effectively prevent separation on the rolling surface caused by water intrusion, and has excellent long-term durability. The purpose is to provide rolling bearings.

An automotive electrical equipment / auxiliary rolling bearing according to the present invention is an automotive electrical equipment / auxiliary rolling bearing that rotatably supports a rotating shaft that is driven to rotate by engine output on a stationary member, the rolling bearing comprising an inner ring and An outer ring and a plurality of rolling elements interposed between the inner ring and the outer ring, and a seal member for sealing grease around the rolling elements is provided at both axial end openings of the inner ring and the outer ring, The grease is a water-resistant grease obtained by blending a base grease composed of a non-aqueous base oil and a thickener with an additive containing at least an aqueous dispersant, and the non-aqueous base oil is a mineral oil or a poly-α-olefin oil. And at least one oil selected from alkyl diphenyl ether oils, wherein the thickener comprises an aromatic diisocyanate, an alicyclic monoamine and an aromatic monoamine. It consists of an alicyclic-aromatic urea compound obtained by reaction or an aromatic urea compound obtained by reaction of an aromatic diisocyanate and an aromatic monoamine alone, and the water dispersant has a base number of 50 to 500 The amount of saturated water content of the water-resistant grease is such that the saturated moisture content of the water-resistant grease is set to 30% to 60% by weight.

The water dispersant contains sorbitan monooleate. Further, it is characterized by containing 0.5 to 2 parts by weight of the Ca sulfonate and 0.2 to 1 part by weight of the sorbitan monooleate with respect to 100 parts by weight of the base grease.
The thickener is characterized by comprising the alicyclic-aromatic urea compound .

In the rolling bearing for automobile electrical equipment and auxiliary equipment according to the present invention, the water-resistant grease enclosed in the bearing disperses water as fine particles in the grease in the base grease composed of a non-aqueous base oil and a thickener. Since a water dispersant that can be used is blended, 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 can be suppressed, early peeling can be prevented, and automobile electrical equipment / compensation that requires long-term durability under conditions where water enters due to splashing of rainwater or puddles, etc. It can utilize suitably for the rolling bearing for machines.
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.

  As a result of diligent investigations on rolling bearings for automotive electrical equipment and auxiliary equipment that can prevent premature damage when water enters, it is saturated by adding a water dispersant that can disperse water as fine particles in grease. It has been found that a bearing filled with water-resistant grease with controlled moisture content can be maintained without deterioration of the lubrication performance of the rolling contact portion even when water enters. This is because water-resistant grease with controlled saturated water content breaks down the oil film formed by the grease because the infiltrated water becomes fine water particles and is uniformly dispersed in the water-resistant grease and trapped in the continuous phase grease. This is considered to improve the durability of the bearing. The present invention is based on such knowledge.

FIG. 1 shows an example of a rolling bearing for automobile electrical equipment and auxiliary equipment according to the present invention. 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 the outer peripheral surface and an outer ring 3 having an outer ring rolling surface 3a on the inner peripheral surface are arranged concentrically, and the inner ring rolling surface 2a and the outer ring rolling surface 3a. 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. Water-resistant grease 7 is sealed at least around the rolling element 4.

An example of an automobile electrical equipment / auxiliary machine is shown in FIG. FIG. 2 is a sectional view of the structure of the alternator. The alternator is rotatably supported by a pair of ball bearings 1 and 1 in which a water-resistant grease is sealed, and a rotor rotating shaft 11 having a rotor 10 mounted on a pair of frames 9a and 9b forming a housing which is a stationary member. ing. A rotor coil 12 is attached to the rotor 10, and a three-winding stator coil 14 is attached to a stator 13 disposed on the outer periphery of the rotor 10 at a phase of 120 °.
The rotor rotating shaft 11 is rotationally driven with a rotational torque transmitted by a belt (not shown) to a pulley 15 attached to the tip of the rotor rotating shaft 11. The pulley 15 is attached to the rotor rotating shaft 11 in a cantilever state, and vibrations are also generated as the rotor rotating shaft 11 rotates at a high speed. Therefore, the ball bearing 1 that supports the pulley 15 in particular receives a severe load. .

Another example of automobile electrical equipment / auxiliary equipment is shown in FIG. FIG. 3 is a sectional view of the structure of the idler pulley. The idler pulley is used as a belt tensioner for an auxiliary drive belt of an automobile.
This pulley includes a pulley body 16 made of a steel plate press and a single row deep groove ball bearing 1 fitted to the inner diameter of the pulley body 16. The pulley body 16 includes an inner diameter cylindrical portion 16a, a flange portion 16b extending from one end of the inner diameter cylindrical portion 16a to the outer diameter side, an outer diameter cylindrical portion 16c extending in the axial direction from the flange portion 16b, and an inner diameter cylindrical portion 16a. This is an annulus composed of a flange 16d extending from the other end to the inner diameter side. The outer ring 3 of the ball bearing 1 is fitted to the inner diameter of the inner cylindrical portion 16a, and a pulley peripheral surface 16e that contacts a belt driven by the engine is provided on the outer diameter of the outer cylindrical portion 16c. By bringing the pulley peripheral surface 16e into contact with the belt, the pulley serves as an idler.

  The ball bearing 1 includes an outer ring 3 fitted to the inner diameter of the inner cylindrical portion 16a of the pulley body 28, an inner ring 2 fitted to a fixed shaft (not shown), and transfer surfaces 2a, 3a of the inner / outer rings 2, 3. The inner ring 2 and the outer ring 3 are composed of a plurality of rolling elements 4 incorporated between them, a cage 5 that holds the rolling elements 4 at equal circumferential intervals, and a pair of seal members 6 that seal water-resistant grease. It is integrally formed.

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. The surfactant is used to disperse water in the grease and render the water harmless so that the oil film does not run out or rust even when water enters the rolling bearings for automobile electrical equipment and accessories. 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 for automobile electrical equipment and auxiliary equipment, and water that adheres to the steel with a low probability. It is considered that the particles cannot be rusted because the particles are immediately replaced with the continuous phase grease by the rotation of the rolling elements interlocking with the rotation of the rolling bearing body for automobile electrical equipment and auxiliary equipment.

  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, refrigerating machine 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 in rotational torque becomes large, which is not preferable.

In the water-resistant grease used 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 becomes difficult to obtain the desired effect sufficiently. 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, Example 2, Example 5 to Example 10, Reference Example 1 to Reference Example 3, 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 Oil Co., Ltd. turbine 100, kinematic viscosity at 40 ° C .: 100 mm ² / sec), 231.7 g of diphenylmethane-4,4′-diisocyanate, 86.2 g of aniline, 91.7 g of cyclohexylamine, The base compound was obtained by uniformly dispersing the formed urea compound. Additives were added to the base grease in the formulation shown in Table 1 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 1.

<Oil film formation rate test>
Bearing used: Angular contact ball bearing 7006ADLLB (outer ring: S53C, inner ring: SUJ2) was used by simulating a rolling bearing for automobile electrical equipment and auxiliary equipment.
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: An angular ball bearing 7006ADLLB was used as a rolling bearing for automobile electrical equipment and auxiliary equipment.
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, inner ring rolling surface, and steel ball was damaged 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 3
In a reaction vessel, 231.7 g of diphenylmethane-4,4′-diisocyanate and 86.2 g of aniline in 1600 g of PAO oil (Nippon Chemical Co., Ltd., Sinfluid 801: Kinematic viscosity at 40 ° C .: 46 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 1.

Example 4
In a reaction vessel, in 1850 g of alkyldiphenyl ether oil (LB100 manufactured by Matsumura Oil Co., Ltd., kinematic viscosity at 40 ° C .: 100 mm ² / sec), 231.7 g of diphenylmethane-4,4′-diisocyanate, 86.2 g of aniline, A base grease was obtained by reacting 91.7 g of cyclohexylamine and uniformly dispersing the formed urea compound. 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 1.

As shown in Table 1, 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. If it 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.

  A rolling bearing for automobile electrical equipment / auxiliary machinery according to the present invention includes a base grease composed of a non-aqueous base oil and a thickener, and a dispersant capable of dispersing water in the grease. Since water-resistant grease whose amount is controlled to 30 to 60% by weight is sealed, even if water enters the grease during the operation of the bearing, it can suppress the action of moisture that inhibits the formation of grease oil film. The early damage of the bearing can be suppressed, and a long life can be obtained even if the lubrication conditions become severe. Therefore, in environments where there is a possibility of water ingress, rolling used in automotive electrical equipment and accessories such as alternators, idler pulleys, electromagnetic clutches for car air conditioners, electric fan motors, etc. that require long-term durability as well as wear resistance. It can be suitably used as a bearing.

It is sectional drawing of a deep groove ball bearing. It is sectional drawing of the structure of an alternator. It is sectional drawing of the structure of an idler pulley.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Deep groove ball bearing 2 Inner ring 3 Outer ring 4 Rolling body 5 Cage 6 Seal member 7 Water resistant grease 8 Opening part 9a, 9b Frame 10 Rotor 11 Rotor rotating shaft 12 Rotor coil 13 Stator 14 Stator coil 15 Pulley 16 Pulley body 16a Inner diameter cylindrical part 16b Flange portion 16c Cylindrical outer diameter portion 16d ridge portion 16e peripheral surface of pulley

Claims (4)

A rolling bearing for automobile electrical equipment and auxiliary equipment that rotatably supports a rotating shaft that is driven to rotate by engine output on a stationary member,
The rolling bearing includes an inner ring and an outer ring, and a plurality of rolling elements interposed between the inner ring and the outer ring, and seal members for sealing grease around the rolling elements at both axial ends of the inner ring and the outer ring. Provided in the opening,
The grease is a water-resistant grease obtained by blending an additive containing at least a water dispersant with a base grease composed of a non-aqueous base oil and a thickener,
The non-aqueous base oil comprises at least one oil selected from mineral oil, poly-α-olefin oil and alkyl diphenyl ether oil;
The thickener is an alicyclic-aromatic urea compound obtained by a reaction of an aromatic diisocyanate with an alicyclic monoamine and an aromatic monoamine, or a reaction of an aromatic diisocyanate with an aromatic monoamine alone. It consists of an aromatic urea compound obtained,
The water dispersant contains Ca sulfonate having a base number of 50 to 500, and the amount of the water dispersant is such that the saturated moisture content of the water resistant grease is set to 30 to 60% by weight. Rolling bearings for automotive electrical equipment and accessories.   The rolling bearing for automobile electrical equipment / auxiliary machinery according to claim 1, wherein the water dispersant contains sorbitan monooleate.   The rolling for automobile electrical equipment / auxiliary equipment according to claim 2, wherein 0.5 to 2 parts by weight of the Ca sulfonate and 0.2 to 1 parts by weight of the sorbitan monooleate are included with respect to 100 parts by weight of the base grease. bearing. 4. The rolling bearing for automobile electrical equipment / auxiliary machinery according to claim 1, wherein the thickener comprises the alicyclic-aromatic urea compound .

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