JP2008095841A - Alternator bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alternator bearing, which has a long life and high reliability. <P>SOLUTION: The bearing 21 for the alternator rotatably supports the rotary shaft of the alternator for an automobile with respect to a casing, the alternator comprising the casing, the rotary shaft, a stator, and a rotor. Concretely, the bearing 21 comprises: an inner race 22 serving as an internal member treated by the dimension stabilizing treatment; an outer race 23 serving as an external member; a plurality of rolling elements 24 arranged between the inner race 22 and the outer race 23; and a grease composition composed of base oil having a kinematic viscosity of 20 to 150 mm<SP>2</SP>/s at 40°C; a thickening agent; and an addition agent containing 0.05 to 10 pts.wt. of dibasic acid metallic salt for 100 pts.wt. of the base oil and the thickening agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a grease composition, and in particular, a grease composition for a rolling bearing such as an alternator, an electromagnetic clutch for a car air conditioner, an intermediate pulley, an electric fan motor, and an auxiliary machine, and a grease in which the grease composition is enclosed. The present invention relates to a composition-enclosed bearing.

  A conventional automotive alternator includes a casing, a rotating shaft rotatably supported on the casing by a bearing, a stator fixed to the casing, a rotor fixed to the rotating shaft at a position facing the stator, and a rotating shaft. And a fixed pulley.

  In addition, the bearing that rotatably supports the rotating shaft includes an inner ring, an outer ring, a plurality of rolling elements disposed between the inner ring and the outer ring, a cage that holds an interval between adjacent rolling elements, and a bearing interior. A rolling bearing provided with a hermetic seal for sealing. And the grease composition is mainly used for lubrication of this rolling bearing.

Furthermore, as a method for preventing the peeling phenomenon of the rolling contact surface of the rolling bearing that occurs with high-speed rotation and high temperature of the alternator for automobiles, for example, a method of adding a passivating agent to a grease composition is disclosed in JP-A-3-210394. Japanese Patent Laid-Open No. 6-803565 (Patent Document 2) discloses a method for extending the peeling life of a bearing by means of adding an antimony compound or a molybdenum compound.
JP-A-3-210394 JP-A-6-803565

  In automobiles, the spread of FF (front engine / front drive) vehicles aimed at miniaturization and weight reduction, and further expansion of the living space forced the reduction of the engine room, further reducing the size and weight of alternators. Yes. In addition, high performance and high output alternators are increasingly required. For example, the reduction in output due to the miniaturization of the alternator is compensated for by increasing the speed. Furthermore, since the engine room is being sealed due to a demand for improvement in quietness, and the high temperature in the engine room is promoted, parts that can withstand higher temperatures are required.

  As a result, the use environment is becoming strict for the bearing supporting the rotating shaft. In particular, an alternator for an automobile has a problem that an electric load increases with an increase in electric power used, and the bearing temperature further increases due to heat generation. The bearing subjected to the standard heat treatment has little dimensional change up to about 120 ° C., but the dimensional change (expansion) increases when the temperature exceeds 120 ° C. In particular, when the expansion of the inner ring increases, the clearance of the bearing becomes excessive, and smooth rotation is hindered.

  In addition, sodium nitrite, which is a typical passivating agent, is known to react with a secondary amine under acidic conditions to produce N-nitrosamine. Since this nitrosamine is an environmentally hazardous substance, its use is not preferred, but there is a problem that there is no alternative additive. Sodium nitrite is also effective as a rust preventive agent, and it is frequently used in rolling bearing grease compositions used in automobile parts where moisture enters from the bottom of the vehicle body during traveling. Yes. In addition, there is a problem that a passivating agent other than sodium nitrite, an antimony compound, or a molybdenum compound contains a heavy metal that may adversely affect the human body or the environment.

  Furthermore, this problem applies not only to automobile alternators, but also to electric components such as electromagnetic clutches for car air conditioners, intermediate pulleys, electric fan motors, auxiliary machines, and the like.

  Accordingly, an object of the present invention is to provide a grease composition that has a long life under high temperature use, has a smooth rotation function, does not adversely affect the human body and the environment, and is excellent in rust prevention, and this grease composition is enclosed. By using such a rolling bearing, a long-life and reliable alternator bearing is provided.

An alternator bearing according to the present invention includes a casing, a rotating shaft housed in the casing, a stator fixed inside the casing, and a rotor that is disposed at a position facing the stator and rotates integrally with the rotating shaft. A rotating shaft of an automobile alternator is rotatably supported by a casing. Specifically, the inner member subjected to the dimensional stabilization treatment, the outer member, a plurality of rolling elements disposed between the inner member and the outer member, and a kinematic viscosity at 40 ° C. of 20 to 150 mm ² / s base oil, thickener, and additive containing 0.05 to 10 parts by weight of the dibasic acid metal salt represented by the formula (1) with respect to 100 parts by weight of the base oil and thickener. A blended grease composition.

(M ₁ and M ₂ represent the same or different alkali metals, and R ₁ represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group, respectively)
The alternator bearing in which the inner member is subjected to dimensional stabilization as described above is the distance between the raceway surfaces at high temperatures ("the outer diameter surface of the inner member holding the rolling elements and the inner diameter surface of the outer member Therefore, the rolling element can maintain smooth rotation even in a high temperature environment.

  Further, by using the dibasic acid metal salt represented by the formula (1) as an additive of the grease composition, an alternator bearing excellent in rust prevention can be obtained without adversely affecting the human body and the environment.

  Preferably, the base oil contains an alkyl diphenyl ether oil. Alkyl diphenyl ether oil is suitable for a bearing that supports the rotating shaft of an automotive alternator because it is excellent in lubrication performance and lubrication life at high temperatures and high speeds.

  Preferably, the thickener is a urea thickener. And the urea type | system | group thickener is mix | blended 5-15 wt% with respect to the total amount of a base oil and a thickener.

  More preferably, the urea-based thickener is an aromatic diurea compound represented by the formula (2).

(R ₂ and R ₄ are the same or different aromatic hydrocarbon groups having 6 to 15 carbon atoms, and R ₃ represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, respectively)
Urea thickeners are generally excellent in high temperature properties. Further, in the formula (2), when the carbon number of R ₂ , R ₃ , R ₄ is less than 6, the heat resistance of the thickener is inferior, and the thickening property exceeding 15 is inferior, so that it is within the above range. Is desirable.

  Preferably, the additive contains 0.05 to 5 parts by weight of an antioxidant containing sulfur with respect to 100 parts by weight of the base oil and thickener.

  By using the base oil, thickener, and additive contained in the grease as described above, an alternator bearing that can be used in a high temperature, rapid acceleration / deceleration environment can be obtained.

  According to the present invention, a long-life and highly reliable alternator bearing can be obtained by applying a dimensional stabilization process to the bearing ring as a bearing for supporting the rotating shaft and enclosing the grease having the above-described configuration. .

  With reference to FIG. 1 and FIG. 2, the alternator 11 for vehicles which concerns on one Embodiment of this invention and the deep groove ball bearing 21 as a bearing for alternators employ | adopted as the alternator 11 for vehicles are demonstrated. 1 is a cross-sectional view of the alternator 11 for an automobile, and FIG. 2 is a cross-sectional view of the deep groove ball bearing 21.

  First, referring to FIG. 1, an automotive alternator 11 includes, as main components, a casing 12, a rotating shaft 13, a pulley 14, a stator 15, a rotor 16, and a deep groove ball bearing 21 as a rolling bearing. With.

  The casing 12 is configured by bolting a front bracket 12a and a rear bracket 12b. And the rotating shaft 13, the stator 15, the rotor 16, and the deep groove ball bearing 21 grade | etc., Are accommodated.

  The rotary shaft 13 is rotatably supported on the casing 12 by two deep groove ball bearings 21. Further, it is inserted through the pulley 14 outside the casing 12 and through the rotor 16 and the slip ring 17 inside the casing 12. A brush 18 is pressed against the slip ring 17 by a spring 19.

  An endless belt (not shown) is attached to the pulley 14 and rotates the rotating shaft 13 as the engine (not shown) rotates. Moreover, in this embodiment, it functions also as a fan which cools the alternator 11 for motor vehicles.

  The stator 15 is a ring-shaped member and is fixed to the casing 12. On the other hand, the rotor 16 is fitted and fixed to the rotary shaft 13 and rotates integrally with the rotary shaft 13. The stator 15 and the rotor 16 are arranged so as to face each other, and a predetermined gap is provided between them. The stator 15 and the rotor 16 are each wound with a coil.

  The automotive alternator 11 having the above configuration converts part of the engine power into electricity. Specifically, the rotating shaft 13 and the rotor 16 rotate integrally with the rotation of the engine. At this time, electricity is generated between the stator 15 and the rotor 16 by the principle of electromagnetic induction. The electricity generated by the automobile alternator 11 is charged in a battery (not shown) and used for the operation of each electrical component.

  Next, referring to FIG. 2, the deep groove ball bearing 21 includes an inner ring 22 as an inner member, an outer ring 23 as an outer member, and a plurality of rolling elements disposed between the inner ring 22 and the outer ring 23. Ball 24, a retainer 25 that holds the interval between adjacent balls 24, and a sealing seal 26 as a sealing member that seals both ends. Further, in order to maintain the smooth rotation of the ball 24, the bearing is filled with grease.

  Here, the inner ring 22 and the outer ring 23 are subjected to dimensional stabilization processing. Specifically, tempering is performed at a temperature higher by about 50 to 100 ° C. than the operating temperature of the deep groove ball bearing 21, that is, the temperature when the alternator 11 for an automobile is operated.

  Note that “tempering” refers to a process of reducing residual stress and internal strain caused by quenching and improving the toughness of steel and the like, and is classified into the following three stages according to the tempering temperature. First, in the first stage of tempering at a relatively low temperature, tetragonal martensite generated by quenching precipitates carbides and approaches a cubic crystal. At this time, the steel shrinks. Next, in the second stage in which tempering is performed at a temperature of about 200 to 230 ° C., the retained austenite is decomposed into tetragonal martensite and carbides. At this time, the steel expands. Finally, in the third stage of tempering at a higher temperature, tetragonal martensite decomposes into cubic ferrite and cementite. At this time, the steel shrinks.

  By selecting an appropriate tempering temperature according to the use conditions of the alternator 11 for automobiles, the volume changes of the inner ring 22 and the outer ring 23 accompanying the temperature rise during use are reduced. As a result, since the change in the distance between the raceway surfaces of the inner ring 22 and the outer ring 23 is reduced, the deep groove ball bearing 21 in which the ball 24 can rotate smoothly can be obtained. Furthermore, the aging change of the inner ring 22 and the outer ring 23 can be reduced by adjusting the distance between the product cages in the quenching oil.

  Further, as a method for further stabilizing the dimensions of the inner ring 22 and the outer ring 23, a sub-zero treatment is added between quenching and tempering. “Sub-zero treatment” refers to a treatment of maintaining a temperature of 0 ° C. or lower (for example, −60 ° C. to −196 ° C.) in order to transform residual austenite into martensite, and in this embodiment, −65 ° C. Hold at temperature for 2 hours. Thereby, the secular change of the inner ring 22 and the outer ring 23 is reduced, and the hardness of the material further increases. In addition, since it is necessary to perform this process before a retained austenite stabilizes, it is desirable to perform within 2 hours after quenching.

  In the above-described embodiment, the example in which the dimensional stabilization process is performed on both the inner ring 22 and the outer ring 23 has been described. Can do. At this time, when the inner ring 22 expands, the distance between the raceway surfaces decreases, and when the outer ring 23 expands, the distance between the raceway surfaces increases. Therefore, from the viewpoint of maintaining smooth rotation of the balls 24, it is desirable to perform dimension stabilization processing on at least the inner ring 22.

  Next, the grease used for the deep groove ball bearing 21 will be described. The grease composition is configured by blending a base oil, a thickener, and an additive, which will be described later.

The base oil of the grease has a kinematic viscosity at 40 ° C. is 20 to 150 mm ² / s, preferably be used as long as 50 to 100 mm ² / s. If the kinematic viscosity is less than 20 mm ² / s, the heat resistance is inferior, and if it exceeds 150 mm ² / s, a problem arises because the rotational heat generation is large. Examples of the base oil having the above viscosity range include mineral oils, synthetic oils, and mixed oils usually used in grease compositions. Examples of the mineral oil include paraffinic mineral oil and naphthenic mineral oil.

  Synthetic oils include synthetic hydrocarbon oils, ether oils, ester oils, and the like. Specifically, as ether oils, alkyl diphenyl ether oils, alkyl triphenyl ether oils, alkyl tetraphenyl ether oils, etc. are used as ester oils. Diester oils, polyol ester oils or their complex ester oils, aromatic ester oils and the like can be exemplified.

  Among these base oils, base oils containing alkyl diphenyl ether oils that are excellent in lubrication performance at high temperature and high speed and lubrication life are preferred. The base oil may be composed of the alkyl diphenyl ether oil alone, or may be mixed with other synthetic oils or mineral oils. In the case of a mixed base oil, in order to obtain excellent lubrication performance and lubrication life, at least 20 wt%, preferably 60 wt% or more of alkyldiphenyl ether oil is blended with respect to the entire base oil.

  As the alkyl diphenyl ether oil, a monoalkyl diphenyl ether oil represented by the following formula (3) and / or a dialkyl diphenyl ether oil represented by the formula (4) can be used.

Here, R ₅ , R ₆ and R ₇ are each an alkyl side chain having 8 to 20 carbon atoms, and are bonded to one phenyl ring or to two phenyl rings. Of these, dialkyl diphenyl ether oils having alkyl side chains R ₆ and R ₇ are preferred in view of heat resistance and evaporation characteristics. Even in a base oil containing an alkyl diphenyl ether oil, the kinematic viscosity is 20 to 150 mm ² / s at 40 ° C.

  As the dibasic acid metal salt represented by the formula (1) added as an essential component to the grease composition, a metal salt of an aliphatic or aromatic dibasic acid can be used. Examples of dibasic acids include malonic acid, methyl malonic acid, succinic acid, methyl succinic acid, dimethyl malonic acid, ethyl malonic acid, glutaric acid, adipic acid, dimethyl succinic acid, pimelic acid, tetramethyl succinic acid, suberic acid, azelaic acid , Sebacic acid, brassic acid, phthalic acid and the like. Moreover, as a metal which comprises a metal salt, monovalent metals, such as alkali metals, such as lithium, sodium, and potassium, are suitable.

In the formula (1), M ₁ and M ₂ may be the same alkali metal, or different types of alkali metals may be used as the metal salt of the dibasic acid. Among the above-mentioned dibasic acid metal salts, preferred dibasic acid metal salts are alkali metals in which M ₁ and M _{2 in the} formula (1) are the same. Examples of such dibasic acid metal salts include sodium azelate, sodium sebacate, sodium adipate, and potassium sebacate, and more preferable dibasic metal salts include anticorrosive greases that do not contain sodium nitrite. Sodium sebacate that can greatly improve performance and lubrication life at high temperatures.

  The dibasic acid metal salt represented by the formula (1) is blended in an amount of 0.05 to 10 parts by weight, preferably 0.5 to 5 parts by weight based on 100 parts by weight of the total amount of the base oil and the thickener. . If the amount is less than 0.05 parts by weight, the effect does not appear, and if it exceeds 10 parts by weight, the grease gels and there is a problem in use.

  As the thickener that can be used in the present invention, the thickener used in usual grease compositions can be used. For example, metal soap, composite soap, urea compound, organic bentonite, silica and the like can be mentioned.

  Examples of the metal soap include 12-hydroxy lithium stearate, lithium stearate, lithium complex and the like. Examples of the urea compound include aliphatic diurea, alicyclic diurea, aromatic diurea, triurea, tetraurea, urea urethane, and the like. Examples of the organic bentonite include montmorillonite treated with a quaternary ammonium salt. Examples of the silica include ultrafine silica powder produced by a gas phase reaction or a powder obtained by treating the surface with a lower alcohol such as methanol. Other examples include sulfonate complex and tetrafluoroethylene resin powder.

  Of the thickeners, urea compounds having excellent high temperature characteristics are preferred. More preferred is an aromatic diurea compound represented by the above formula (2).

In the aromatic diurea compound represented by the above formula (2), R ₂ and R ₄ are aromatic hydrocarbon groups having 6 to 15 carbon atoms, and may be the same group or different groups. . When the carbon number is less than the above range, the heat resistance of the thickener is inferior, and when it exceeds the above range, the thickener is inferior. Examples of R ₂ and R ₄ include a phenyl group, triyl group, xylyl group, t-butylphenyl group, and benzyl group. R ₃ is an aromatic hydrocarbon group having 6 to 15 carbon atoms. If the carbon number is less than the above range, the thickening property of the grease is poor, and if it exceeds the above range, the grease is easily cured. Examples of R ₃ include aromatic monocycles, aromatic condensed rings, groups in which these are connected by a methylene chain, cyanuric ring, isocyanuric ring, and the like. Preferred aromatic hydrocarbon groups include the following formulas ( Examples include groups represented by 5) to (7).

  Specific examples of particularly preferable groups among these groups include groups represented by the following formulas (8) to (10).

  By using an aromatic diurea compound as a thickener, the heat resistance of the grease composition is improved. The aromatic urea compound is obtained by reacting an isocyanate compound with an amino compound. In order not to leave a reactive free radical, the isocyanate group of the isocyanate compound and the amino group of the amino compound are preferably blended so as to be approximately equivalent.

  In the grease composition, an isocyanate compound and an amino compound may be reacted in a base oil, or a urea compound synthesized in advance may be mixed with the base oil. A preferable production method is the former method in which the stability of the grease composition is easily maintained.

  The blending ratio of the aromatic urea thickener is 5 to 30 wt% with respect to the total amount of base oil and thickener. If it is less than 5 wt%, it becomes a low-viscosity liquid and easily leaks, making it difficult to seal the bearing. On the other hand, if it exceeds 30 wt%, it will solidify and the consistency will be 200 or less, so that it will not be practical as a grease composition for bearings.

  The grease composition according to the present invention comprises a dibasic acid metal salt as an essential component for the above base oil and thickener, but is an extreme pressure agent, an antioxidant, a rust inhibitor, and a metal inert. Conventional additives for grease such as an agent and an oily agent can be further blended.

  By blending an extreme pressure agent, load resistance and extreme pressure properties can be improved. For example, the following compounds can be used. Examples of organometallic compounds include: organic zinc compounds such as zinc dithiocarbamate, zinc dithiophosphate, zinc phenate, organic selenium compounds such as selenium dithiocarbamate, organic bismuth compounds such as bismuth naphthenate and bismuth dithiocarbamate, iron dithiocarbamate, Organic iron compounds such as iron octylate, organic copper compounds such as copper dithiocarbamate and copper naphthenate, organic lead compounds such as lead naphthenate and lead dithiocarbamate, organic tin compounds such as tin maleate and dibutyltin sulfide, or Organic metal compounds such as alkali metal, alkaline earth metal organic sulfonates, phenates, phosphonates, gold, silver, titanium, cadmium and the like can be used if necessary. As the sulfur compounds, sulfides such as dibenzyl disulfide or polysulfide compounds, sulfurized fats and oils, ashless carbamic acid compounds, thiourea compounds, thiocarbonates, and the like can be used. As the phosphoric acid extreme pressure agent, it is possible to use phosphate compounds such as trioctyl phosphate, tricresyl phosphate, etc., phosphate esters, acidic phosphate esters, phosphite esters, acidic phosphite esters, etc. it can. In addition, halogen-based extreme pressure agents such as chlorinated paraffin, or solid lubricants such as boron compounds such as molybdenum disulfide, tungsten disulfide, graphite, ethylene tetrafluoride, antimony sulfide, and boron nitride are used. be able to. Among these extreme pressure agents, dithiocarbamic acid compounds and dithiophosphoric acid compounds can be suitably used.

  As an antioxidant, it can be used by appropriately selecting from an antioxidant, an ozone deterioration inhibitor and an antioxidant added to rubber, plastic, lubricating oil and the like. For example, the following compounds can be used. That is, phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, p, p-dioctyldiphenylamine, N, N-diisopropyl-p-phenylenediamine, N, N-di-sec- Amine compounds such as butyl-p-phenylenediamine can be used.

  Also preferably, sulfur-containing antioxidants and phenolic antioxidants can be used. Sulfur-containing antioxidants include, for example, alkyl dithiophosphates, dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate, ditridecyl thiodipropionate, phenothiazine, N-methylphenothiazine , N-ethylphenothiazine, 3,7-dioctylphenothiazine and the like.

  Examples of phenolic antioxidants include 2,6-di-tert-dibutylphenol, n-octadecyl-3- (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate, tetrakis- ( Methylene-3- (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate) methane, 2,2′-methylenebis- (4-methyl-6-tert-butylphenol), 4,4′- And butylidenebis- (3-methyl-6-tert-butylphenol).

  As a rust inhibitor, for example, the following compounds can be used. That is, ammonium salts of organic sulfonic acids, alkali metals such as barium, zinc, calcium and magnesium, organic sulfonates of alkaline earth metals, phenates, phosphonates, alkyls such as alkyl or alkenyl succinic acid esters, alkenyl succinic acid derivatives, sorbitan Partial esters of polyhydric alcohols such as monooleate, hydroxy fatty acids such as oleoylsarcosine, mercapto fatty acids such as 1-mercaptostearic acid or metal salts thereof, higher fatty acids such as stearic acid, isostearyl alcohol, etc. Higher alcohols, esters of higher alcohols and higher fatty acids, thiazoles such as 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptothiadiazole, 2- (decyldithio) -benzimidazole, Imidazole compounds such as emission zone imidazole, or phosphoric acid esters such as tris nonylphenyl phosphite, may be used thiocarboxylic acid ester compounds such as dilauryl thiodipropionate and the like.

  As the metal deactivator, for example, a triazole compound such as benzotriazole or tolyltriazole can be used.

  As the oily agent, for example, the following compounds can be used. That is, fatty acids such as oleic acid and stearic acid, fatty acid alcohols such as oleic alcohol, fatty acid esters such as polyoxyethylene stearic acid ester and polyglyceryl oleic acid ester, phosphoric acid, tricresyl phosphate, lauric acid ester or polyoxyethylene oleyl Phosphoric esters such as ether phosphoric acid can be used.

  Since the grease composition having the above configuration uses an additive not containing nitrite, the deep groove ball bearing 21 having excellent environmental resistance is obtained. Moreover, since it is excellent in rust prevention, it is suitable for an alternator bearing that supports the rotating shaft 13 of the automotive alternator 11.

  Next, in order to confirm the effect of the present invention, the grease composition shown in Table 1 was subjected to a high-temperature high-speed test, a rapid acceleration / deceleration test, and a rust prevention test. Test methods and test conditions are shown below. The results are shown in Table 1.

  A base oil composed of a hybrid oil of poly-α-olefin oil (trade name, Shinflud 601 manufactured by Nippon Steel Chemical Co., Ltd.) and alkyl diphenyl ether oil (trade name, manufactured by Matsumura Oil Co., Ltd., LB100) was prepared at a blending ratio shown in Table 1. This base oil is divided into two liquids, and 4,4'-diphenylmethane diisocyanate is dissolved in half of the base oil, and the remaining half of the base oil has a double equivalent of 4,4'-diphenylmethane diisocyanate. Toluidine was dissolved. In addition, 4,4'-diphenylmethane diisocyanate was dissolved so as to have a blending ratio shown in Table 1 as an aromatic diurea compound. The p-toluidine solution was added while stirring the solution in which 4,4′-diphenylmethane diisocyanate was dissolved, and then the reaction was continued with stirring at 100 to 120 ° C. for 30 minutes to mix the aromatic diurea compound with the base oil. . To this, sorbitan trioleate, sodium sebacate and antioxidant were added at the blending ratio shown in Table 1, and the mixture was further stirred at 100 to 120 ° C. for 10 minutes. Thereafter, the mixture was cooled and homogenized with three rolls to obtain a grease composition.

  As a high-temperature high-speed test, 0.7 g of a test grease composition is sealed in a rolling bearing (6204) and rotated at a rotation speed of 10,000 rpm under a bearing outer ring outer diameter temperature of 150 ° C., a radial load of 67 N, and an axial load of 67 N. The time until seizure was measured.

  As a rapid acceleration / deceleration test, a rapid acceleration / deceleration test was conducted on a rolling bearing that supports a rotating shaft that supports a pulley around which a rotating belt of an alternator as an example of an electrical accessory is wound. The rapid acceleration / deceleration test conditions were set such that the load applied to the pulley was 3234N and the rotation speed was 0 to 18000 rpm. Then, abnormal peeling occurred in the bearing, and the time when the generator stopped when the vibration of the vibration detector exceeded the set value was measured.

  According to the rust test method specified in ASTM D 1743, the test conditions were performed under conditions more severe with respect to rust generation. After 1.9 to 2.1 g of the test grease composition was sealed in a tapered roller bearing 30204 that had been degreased and dried in advance with an organic solvent, an axial load was applied to 98 N, and the test was run for 1 minute at 1800 rpm. Next, after immersing in 1 wt% saline, the bearing was placed in a sealed high-humidity container that reached a saturated water vapor pressure at 40 ° C. and left at 40 ° C. for 48 hours, and then the rusting state was examined. As for the rusting situation, the outer race was divided into 32 equal parts in the circumferential direction, the rusted sections were counted, and the rust occurrence rate was measured. The average of the number of tests n = 4 was taken as the rust score.

  A base grease was prepared by selecting a thickener and a base oil in the blending ratio shown in Table 1 by the method according to Example 1, and further blended with additives to obtain a grease composition. In Example 3, Example 4, Example 6, and Example 8, alkyl diphenyl ether oil was used alone as a base oil. The obtained grease was evaluated by conducting the same test as in Example 1. The results are shown in Table 1.

  A base grease was prepared by selecting a thickener and a base oil at the blending ratio shown in Table 2 by the method according to Example 1, and further blended with additives to obtain a grease composition. The obtained grease composition was evaluated by performing the same test as in Example 1. The results are shown in Table 2.

  As shown in each example, the grease composition according to the present invention satisfied all of the high-temperature high-speed test, rapid acceleration / deceleration test, and rust prevention test.

In the grease composition according to the present invention, the base oil has a kinematic viscosity at 40 ° C. of 20 to 150 mm ² / s, and a dibasic acid metal salt represented by the formula (1) is used as an essential component of the additive. And 0.05 to 10 parts by weight with respect to 100 parts by weight of the total amount of the thickener, all of the results of the high-temperature high-speed test, rapid acceleration / deceleration test and rust prevention test are not adversely affected by human body and environment A grease composition satisfying the above can be obtained.
In addition, since the base oil contains alkyl diphenyl ether oil and the thickener is a urea-based thickener, especially an aromatic diurea compound represented by the formula (2), the results of high-temperature high-speed test, rapid acceleration / deceleration test, and rust prevention test Is better.

  Moreover, since the said additive contains 0.05-5 weight part with respect to 100 weight part of total amounts of base oil and a thickener, respectively, the antioxidant containing sulfur and a phenolic antioxidant, A high temperature high speed test The rapid acceleration / deceleration test and rust prevention test results are more excellent.

  Further, in the deep groove ball bearing 21 having the above-described configuration, the inner ring 22 and / or the outer ring 23 are subjected to a dimensional stabilization process, and the grease of the above composition is sealed inside the bearing, whereby the rotation of the ball 24 is stabilized. As a result, a long-life and highly reliable alternator bearing 21 can be obtained.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The present invention is advantageously used for alternator bearings.

It is sectional drawing of the alternator for motor vehicles based on one Embodiment of this invention. It is sectional drawing of the deep groove ball bearing used for the alternator for motor vehicles shown in FIG.

Explanation of symbols

  11 Automotive Alternator, 12 Casing, 12a Front Bracket, 12b Rear Bracket, 13 Rotating Shaft, 14 Pulley, 15 Stator, 16 Rotor, 15a, 16a Coil, 17 Slip Ring, 18 Brush, 19 Spring, 21 Deep Groove Ball Bearing, 22 Inner ring, 23 Outer ring, 24 balls, 25 Cage, 26 Seal seal.

Claims (5)

A casing,
A rotating shaft housed in the casing;
A stator fixed inside the casing;
An alternator bearing for rotatably supporting the rotating shaft of the automotive alternator, which is disposed at a position facing the stator and having a rotor that rotates integrally with the rotating shaft, on the casing,
An inner member that has been subjected to dimensional stabilization treatment;
An outer member;
A plurality of rolling elements disposed between the inner member and the outer member;
A base oil having a kinematic viscosity at 40 ° C. of 20 to 150 mm ² / s, a thickener, and a dibasic acid metal salt represented by the formula (1) is added to 0.1 parts by weight with respect to 100 parts by weight of the base oil and the thickener. A bearing for an alternator having a grease composition containing an additive containing 05 to 10 parts by weight.

(M ₁ and M ₂ represent the same or different alkali metals, and R ₁ represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group, respectively)   The alternator bearing according to claim 1, wherein the base oil contains an alkyl diphenyl ether oil. The thickener is a urea thickener,
The alternator bearing according to claim 1 or 2, wherein the urea-based thickener is blended in an amount of 5 to 15 wt% with respect to the total amount of the base oil and the thickener. 4. The alternator bearing according to claim 3, wherein the urea-based thickener is an aromatic diurea compound represented by the formula (2).

(R ₂ and R ₄ are the same or different aromatic hydrocarbon groups having 6 to 15 carbon atoms, and R ₃ represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, respectively)   The alternator bearing according to any one of claims 1 to 4, wherein the additive contains 0.05 to 5 parts by weight of an antioxidant containing sulfur with respect to 100 parts by weight of the base oil and the thickener. .

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