JP2009120956A - Roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a durable roller bearing which is not flaked with white structural peeling, and is used for automotive electric components, engine accessories, electromagnetic clutches for gas heat pumps and compressors. <P>SOLUTION: The roller bearing for automotive electric components, engine accessories, electromagnetic clutches for gas heat pumps and compressors is obtained by beforehand applying, on at least one of an inner ring, an outer ring and a rolling body, a rustproof oil in which a basic oil selected from mineral oils and synthetic oils whose kinematic viscosity at 40°C is 10 to 400 mm<SP>2</SP>/s comprises at least one of a carboxylic acid based rustproof additive selected from alkyl succinic acid, alkyl succinic acid half ester, alkenyl succinic acid and alkenyl succinic acid half ester, a carboxylate based rustproof additive, and an ester based rust preventive, in the ratio of 0.1 to 20 mass%, and thereafter sealing a grease therein. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention can be used in places that are prone to exfoliation accompanied by white tissue change, such as automotive electrical parts, alternators and intermediate pulleys that are engine auxiliary machines, electromagnetic clutches for car air conditioners, electromagnetic clutches for gas heat pumps, and compressors. The present invention relates to a rolling bearing having a peeling life.

  Rolling bearings used in the above-mentioned automotive electrical parts, engine alternators and intermediate pulleys, car air conditioner electromagnetic clutches, compressors, etc. are often used at high temperatures, high speeds, and high loads. Due to demands for compactness and high performance, these usage conditions are becoming stricter. Therefore, as described in Patent Document 1, the enclosed grease decomposes to generate hydrogen, and this hydrogen penetrates into the bearing steel forming the inner ring, the outer ring, and the rolling element, and the white structure changes due to hydrogen embrittlement. Peeling (hereinafter referred to as “white tissue peeling”), and prevention thereof has become a new important issue.

  In addition, these rolling bearings are belt-driven auxiliary machine bearings outside the engine, so that muddy water and rainwater splashed from the road surface are likely to enter. These rolling bearings are usually configured to prevent water from entering from the outside with a contact rubber seal, but at present, they cannot be completely prevented. Furthermore, since the engine of an automobile is a machine that repeatedly operates and pauses, when the engine is paused, the temperature in the bearing housing decreases, reaches the dew point, and moisture in the air around the bearing condenses and drops of water. This water droplet may adhere to the bearing and be mixed into the grease. As a result, as described in Patent Document 2, hydrogen from the infiltrated moisture causes similar white tissue peeling, and the white tissue peeling is more likely to occur in combination with the hydrogen from the above-described grease.

  As countermeasures against white tissue peeling, there are many cases using encapsulated grease. For example, Patent Document 1 contains a grease containing a passive oxidizing agent such as sodium nitrite, Patent Document 3 shows a grease containing an organic antimony compound or an organic molybdenum compound, Patent Document 4 proposes to enclose grease containing an inorganic compound having a particle size of 2 μm or less. These prevent the penetration | invasion of the hydrogen to a bearing material by producing | generating the film derived from a compound in a rolling contact part. However, hydrogen cannot be prevented from entering until the film is formed, and if the rolling element slips due to vibration or speed fluctuation, metal peeling occurs at the rolling contact part and the generated film is destroyed. Hydrogen enters.

  For example, Patent Document 5 proposes a rolling bearing in which the bearing material is stainless steel, and Patent Document 6 proposes a rolling bearing in which the rolling elements are made of ceramics. However, these rolling bearings usually increase costs.

  Moreover, in a rolling bearing, if moisture is mixed in the lubricant, the service life is greatly reduced. For example, Furumura et al. Reported that when 6% of water is mixed in lubricating oil (# 180 turbine oil), rolling fatigue life is reduced by a factor of 1 to 20 times compared to the case of no mixing. (Non-Patent Document 1). Schatzberg et al. Have reported that the rolling strength of steel is reduced by 32 to 48% when only 100 ppm of water is mixed in the lubricating oil (Non-Patent Document 2).

  Therefore, in order to suppress the generation of rust, rust preventive oil is also applied to the inside of the bearing before the grease is sealed. This rust preventive oil is blended with a rust preventive agent to enhance the rust preventive effect, and a sulfonic acid metal salt is generally used because of its high rust preventive ability. However, as pointed out in Patent Document 1, the sulfonic acid metal salt promotes the generation of hydrogen and may cause white tissue peeling, and the sulfonic acid metal salt is adsorbable to metal. Is very high and easily forms a sulfonic acid adsorption film on the surface of the bearing member to inhibit the formation of a film derived from the above compound. Therefore, it is preferably applied to the rolling bearing used in each of the above parts. Absent.

Japanese Patent No. 2878749 JP-A-11-72120 Japanese Patent Publication No. 6-803565 Japanese Patent Laid-Open No. 9-169989 JP-A-3-173747 JP-A-4-244624 Furumura Shinzaburo, Shirota Shinichi, Hirakawa Kiyoshi: NSK Bearing Journal, No636, pp.1-10, 1977 P. Schatzberg, I.M.Felsen: Effects of water and oxygen during rolling contact lubrication, wear, 12, pp.331-342, 1968

  As described above, in each of the component bearings, white structure peeling is likely to occur due to moisture entering from the outside in addition to the use conditions, and the combined use with a rust preventive is difficult. Therefore, the present invention is used for automobile electrical parts, engine auxiliary equipment, electromagnetic clutches for gas heat pumps and compressors, which are used in an environment with high temperature, high speed, high load, and easy to receive water from the outside. An object of the present invention is to provide a long-life rolling bearing without causing tissue peeling.

In order to achieve the above object, the present invention is used in automobile electrical parts, engine accessories, electromagnetic clutches and compressors for gas heat pumps, and holds an inner ring, an outer ring, a plurality of rolling elements, and the rolling elements. A rolling bearing in which grease is enclosed, wherein at least one of the inner ring, the outer ring, and the rolling element is made of mineral oil and synthetic oil having a kinematic viscosity at 40 ° C. of 10 to 400 mm ² / s. Carboxylic acid anticorrosive additive, carboxylate anticorrosive additive and ester anticorrosive selected from alkyl succinic acid, alkyl succinic acid half ester, alkenyl succinic acid, alkenyl succinic acid half ester A rust-preventing oil containing at least one of the above in a proportion of 0.1 to 20% by mass is previously applied, and then grease is sealed. To provide a rolling bearing.

  According to the present invention, it has a very long life with excellent rust prevention performance and anti-peeling effect, and is used in automotive electrical parts, alternators and intermediate pulleys as engine accessories, car air conditioner electromagnetic clutches, gas heat pump electromagnetic clutches, and compressors. A rolling bearing to be used is provided.

  Hereinafter, the rolling bearing of the present invention will be described in more detail.

  The configuration itself of the rolling bearing of the present invention is not limited. For example, a ball bearing 1 shown as a sectional view in FIG. 1 can be exemplified. The ball bearing 1 is configured to hold a plurality of rolling elements balls 13 between an inner ring 10 and an outer ring 11 via a retainer 12 so as to be rotatable at substantially equal intervals. The bearing space S formed by the balls 13 is filled with a predetermined amount of grease and sealed with a seal 14.

  However, in the present invention, the antirust oil shown below is applied to at least one of the inner ring 10, the outer ring 11 and the ball 13 of the ball bearing 1.

  The rust preventive oil is based on mineral oil or synthetic oil, and it contains at least one carboxylic acid rust preventive additive, carboxylate rust preventive additive and ester rust preventive agent described later as a rust preventive agent. It is a thing.

[Base oil]
Mineral oil can be used that is purified by appropriately combining vacuum distillation, oil removal, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, white clay purification, hydrorefining, and the like.

  Synthetic oils include hydrocarbon oils, aromatic oils, ester oils, ether oils, and the like. Examples of the hydrocarbon oil include normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, poly-α-olefin such as 1-decene and ethylene co-oligomer, and hydrides thereof. Examples of the aromatic oil include alkylbenzenes such as monoalkylbenzene and dialkylbenzene, and alkylnaphthalenes such as monoalkylnaphthalene, dialkylnaphthalene and polyalkylnaphthalene. Examples of ester oils include dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, and methyl acetyl cinolate, or trioctyl trimellitate. Aromatic ester oils such as tridecyl trimellitate and tetraoctyl pyromellitate, as well as polyols such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol belargonate Further, ester oils, and complex ester oils that are oligoesters of polyhydric alcohols and mixed fatty acids of dibasic acids and monobasic acids are exemplified. Examples of ether oils include polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether, or monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, monoalkyl tetra And phenyl ether oils such as phenyl ether and dialkyl tetraphenyl ether. These synthetic oils can be used alone or as a mixture.

The mineral oil and synthetic oil have a kinematic viscosity at 40 ° C. of 10 to 400 mm ² / sec, preferably 20 to 250 mm ² / sec in order to prevent generation of abnormal noise at low temperature startup due to insufficient low temperature fluidity. It is desirable to use

[anti-rust]
Examples of the carboxylic acid-based rust preventive include alkyl succinic acid, alkyl succinic acid half ester, alkenyl succinic acid, and alkenyl succinic acid half ester.

  Examples of the carboxylate-based rust preventive include metal salts such as fatty acid, naphthenic acid, abietic acid, lanolin fatty acid, alkenyl succinic acid, and amino acid derivatives. Examples of the metal element include cobalt, manganese, zinc, aluminum, calcium, barium, lithium, magnesium, copper and the like.

  Examples of ester-based rust inhibitors include partial esters of polyhydric alcohols such as sorbitol, pentaerythritol, sucrose, and glycerin and carboxylic acids such as oleic acid and lauric acid, and higher fatty acid alcohols such as oleyl alcohol, stearyl alcohol, and lauryl alcohol. Is mentioned.

  The carboxylic acid rust inhibitor, carboxylate rust inhibitor, and ester rust inhibitor may be used alone or in combination of two or more.

[concentration]
The compounding quantity of a rust preventive agent is 0.1-20 mass% with respect to rust preventive oil whole quantity. If the amount of the rust inhibitor is less than 0.1% by mass, sufficient rust prevention performance cannot be imparted. On the other hand, when the amount exceeds 20% by mass, the amount of the rust inhibitor adsorbed on the bearing member surface becomes too large, and the formation of an oxide film or the like derived from the encapsulated grease may be hindered to cause white tissue peeling. Come. When the antirust performance is ensured and white structure peeling is taken into consideration, the blending amount of the antirust agent is preferably 0.25 to 15% by mass with respect to the total amount of the antirust oil.

[Organic metal salt]
In order to suppress the occurrence of white tissue peeling, it becomes more effective if it becomes easier to form an oxide film at the rolling contact portion in addition to the action of the rust inhibitor. Therefore, it is preferable to add an organic metal salt to the rust preventive oil.

  In combination with the above rust preventive agent, as an organic metal salt that can more effectively suppress the occurrence of white tissue peeling, a dialkyldithiocarbamic acid (DTC) compound represented by the following general formula (1), and the following general metal salt The dialkyl dithiophosphoric acid (DTP) type compound represented by Formula (2) can be mentioned.

In the general formulas (1) and (2), M represents a metal species, and specifically can be selected from Sb, Bi, Sn, Ni, Te, Se, Fe, Cu, Mo, and Zn. R ₁ and R ₂ may be the same group or different groups, and are selected from an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkylaryl group, and an arylalkyl group. Particularly preferable groups as R ₁ and R ₂ include 1,1,3,3-tetramethylbutyl group, 1,1,3,3-tetramethylhexyl group, 1,1,3-trimethylhexyl group, 1, 3-dimethylbutyl group, 1-methylundecane group, 1-methylhexyl group, 1-methylpentyl group, 2-ethylbutyl group, 2-ethylhexyl group, 2-methylcyclohexyl group, 3-heptyl group, 4-methylcyclohexyl group N-butyl group, isobutyl group, isopropyl group, isoheptyl group, isopentyl group, undecyl group, eicosyl group, ethyl group, octadecyl group, octyl group, cyclooctyl group, cyclododecyl group, cyclopentyl group, dimethylcyclohexyl group, decyl group Tetradecyl group, docosyl group, dodecyl group, tridecyl group, trimethylcyclohexane Group, nonyl group, propyl group, hexadecyl group, hexyl group, henicosyl group, heptadecyl group, heptyl group, pentadecyl group, pentyl group, methyl group, tert-butylcyclohexyl group, tert-butyl group, 2-hexenyl group, 2 -Methallyl group, allyl group, undecenyl group, oleyl group, decenyl group, vinyl group, butenyl group, hexenyl group, heptadecenyl group, tolyl group, ethylphenyl group, isopropylphenyl group, tert-butylphenyl group, second pentylphenyl group N-hexylphenyl group, tertiary octylphenyl group, isononylphenyl group, n-dodecylphenyl group, phenyl group, benzyl group, 1-phenylmethyl group, 2-phenylethyl group, 3-phenylpropyl group, 1, 1-dimethylbenzyl group, 2-phenylisopropyl group, 3-pheny There are a ruhexyl group, a benzhydryl group, a biphenyl group, and the like, and these groups may have an ether group.

  Moreover, the organozinc compounds represented by the following general formulas (3) to (5) are also suitable as the organometallic salt.

In the general formulas (3) to (5), R ₃ and R ₄ may be the same group or different groups, and are selected from a hydrocarbon group having 1 to 18 carbon atoms and a hydrogen atom. . In particular, mercaptobenzothiazole zinc (general formula (3)), benzamidothiophenol zinc (general formula (4)), mercaptobenzimidazole zinc (general formula (5)), wherein R ₃ and R ₄ are both hydrogen atoms. Can be preferably used.

  Furthermore, zinc alkylxanthate represented by the following general formula (6) is also suitable as the organic metal salt.

In the general formula (6), R ₅ is a hydrocarbon group having 1 to 18 carbon atoms.

  The organometallic salts listed above may be used alone or in admixture of two or more. In addition, the combination at the time of mixing and using is not restrict | limited. Moreover, the addition amount of organometallic salt is 0.1-0.5 mass% with respect to rust preventive oil whole quantity with single use and mixed use. If the amount of the organic metal salt added is less than 0.1% by mass, there is no effect in promoting the formation of an oxide film. There is a risk of abnormally accelerating the oxidation reaction and causing corrosion and abnormal wear.

[Rust prevention oil application method]
The method of applying the anti-rust oil to the rolling bearing is not particularly limited, but after the rolling bearing is immersed in the anti-rust oil and taken out, excess air is blown or a centrifuge is used. A method of removing rust preventive oil is simple and preferable. Further, the coating amount is appropriately adjusted according to the type and size of the bearing.

[Encapsulated grease]
In the present invention, the grease to be sealed for lubrication is not particularly limited, but it is preferable to use a grease that has been sealed for the purpose of preventing white tissue peeling. For example, grease containing a passive oxidant such as sodium nitrite as described in Patent Document 1, grease containing organic antimony compound or organic molybdenum compound as described in Patent Document 3, patent It is preferable to use a grease containing an inorganic compound having a particle size of 2 μm or less as described in Document 4. In particular, it is preferable to use grease containing a component capable of forming an oxide film. In the present invention, even if these greases are used, the use of the above specific anticorrosive agent eliminates the conventional adsorption of the anticorrosive agent to the bearing member and inhibits the formation of an oxide film or the like. Absent.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Production of test bearing-1)
A single-row deep groove ball bearing (inner diameter φ17 mm, outer diameter φ47 mm, width 14 mm) is immersed in each rust-preventing oil prepared with the composition shown in Table 1. Excess rust preventive oil was removed by a separator, and the amount of rust preventive oil in the bearing was adjusted to 100 mg. Next, 2.36 g of grease shown in Table 2 was sealed to produce a test bearing.

(Peel test)
The test bearing was built into the engine alternator and evaluated by rapid acceleration and deceleration. The test conditions were repeated at an engine rotation speed of 1000 to 6000 min ⁻¹ (bearing rotation speed 2400 to 13300 min ⁻¹ ), continuously rotated at a pulley load of 1560 N in a room temperature atmosphere, and a test was conducted with a target of 500 hours. The rotation was stopped when the bearing outer ring raceway was separated and vibrations occurred. Ten tests were performed for each test, and the occurrence probability of peeling was calculated according to the following formula. The results are shown in FIG.
Peeling occurrence probability = (number of peeling occurrence / number of tests) × 100

(Rust prevention test)
A single row deep groove ball bearing (inner diameter φ17 mm, outer diameter φ47 mm, width 14 mm) coated with rust preventive oil in the same manner as described above is maintained in a humid environment of 90% HR at 20 ° C. for 3 hours, and 90% HR at 50 ° C. In this wet environment, holding for 3 hours was repeated alternately and left for 7 days, after which the bearing was disassembled and the state of rust formation on the inner and outer ring raceways was confirmed. The evaluation is as shown below, and the stain rust or less was regarded as acceptable. The results are shown in FIG.
Rust evaluation point 1 2 3 4
Rust situation No rust Blot rust Spot rust Small rust

  From the results of the peeling test and the rust prevention test, carboxylic acid rust preventive additive, carboxylate rust preventive additive or ester rust preventive agent is used as the rust preventive agent, and the total amount of rust preventive oil is 0 It turns out that generation | occurrence | production of white structure | tissue peeling can be reduced significantly by using the antirust oil mix | blended in the ratio of 0.1-20 mass% with the outstanding antirust performance.

(Production of test bearing-2)
A single-row deep groove ball bearing (inner diameter φ17 mm, outer diameter φ47 mm, width 14 mm) is immersed in rust-preventing oil prepared with the composition shown in Table 3, and after taking out, air is blown to drain the liquid, followed by centrifugation. Excess rust preventive oil was removed by a machine, and the amount of rust preventive oil in the bearing was adjusted to 100 mg. Next, 2.36 g of grease shown in Table 4 was sealed to produce a test bearing.

(Peel test)
The test bearing was built into the engine alternator and evaluated by rapid acceleration and deceleration. The test conditions were repeated at an engine speed of 1000 to 6000 min ⁻¹ (bearing rotational speed 2400 to 13300 min ⁻¹ ), continuously rotated at a pulley load of 1560 N in a room temperature atmosphere, and the test was performed with a target of 1000 hours. The rotation was stopped when the bearing outer ring raceway was separated and vibrations occurred. Ten tests were performed for each test, and the occurrence probability of peeling was calculated according to the following formula. The results are shown in FIG.
Peeling occurrence probability = (number of peeling occurrence / number of tests) × 100

(High-speed four-ball wear test)
The test was conducted according to ASTM D 2266 using the high-speed four-ball tester shown in FIG. In the illustrated high-speed four-ball tester, three steel balls 22 are arranged at the apexes of an equilateral triangle so that they are in contact with each other in a recess 21 provided in the center of the pole pot 20, and fixed by a fixture 23. Is done. A steel ball 24 is placed on the center of gravity of an equilateral triangle composed of three steel balls 22 and is rotated at high speed by a chuck 25. A lock nut 26 is screwed onto the ball pot 26 so that a predetermined load can be applied when the steel ball 24 rotates.

For the test, a 1/2 inch steel ball (SUJ2) was used, immersed in the rust-preventing oil shown in Table 3, and after taking out, the air was blown off to drain the liquid. The oil was removed and the coating amount of rust preventive oil was adjusted to 100 mg. Then, the grease shown in Table 4 was applied, and continuously rotated for 60 minutes under the conditions of an atmospheric temperature of 75 ° C., a rotational speed of 1200 min ⁻¹ , and a load of 196 N. The results are shown in FIG. In the evaluation, a wear trace of 1.5 mm or less is acceptable.

  From the results of the peel test and the high-speed four-ball wear test, the addition of 0.1 to 0.5% by mass of a dialkyldithiocarbamic acid compound to the rust preventive agent can further suppress the occurrence of white tissue peeling, and at the same time, It can be seen that the wearability can also be improved.

It is sectional drawing which shows one Embodiment of the rolling bearing of this invention. It is a graph which shows the result of the peeling test in Examples 1-3 and the comparative example 1. FIG. It is a graph which shows the result of the rust prevention test in Examples 1-3 and the comparative example 1. FIG. It is a graph which shows the result of the peeling test in Example 4, and a high-speed four-ball type abrasion resistance test. It is sectional drawing which shows the high-speed four-ball tester used for the high-speed four-ball type abrasion resistance test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball bearing 10 Inner ring 11 Outer ring 12 Cage 13 Ball (rolling element)
14 Seal

Claims (4)

Rolling bearings used in automobile electrical parts, engine accessories, electromagnetic heat clutches and compressors for gas heat pumps, comprising an inner ring, an outer ring, a plurality of rolling elements, and a cage for holding the rolling elements, and enclosing grease And at least one of the inner ring, the outer ring and the rolling element, a base oil selected from a mineral oil and a synthetic oil having a kinematic viscosity at 40 ° C. of 10 to 400 mm ² / s, an alkyl succinic acid, an alkyl succinic acid 0.1-20 mass% of at least 1 sort (s) of the carboxylic acid type rust preventive additive chosen from a half ester, an alkenyl succinic acid, and an alkenyl succinic acid half ester, a carboxylate type | system | group rust preventive additive, and an ester rust preventive agent. A rolling bearing characterized in that a rust preventive oil contained in a proportion is applied in advance and then grease is sealed.   The rolling bearing according to claim 1, wherein the rust preventive oil contains a dialkyldithiocarbamic acid compound in a proportion of 0.1 to 0.5 mass%.   The rolling bearing according to claim 2, wherein the rust preventive oil contains zinc naphthenate and zinc dialkyldithiocarbamate.   The rolling bearing according to claim 1, wherein the grease contains a urea compound as a thickener.

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