JPH10121083A - Grease-prelubricated bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bearing which produces little bearing noise and can attain a stable bearing torque and has excellent resistance to abnormal peeling by using a bearing prelubricated with a specified grease composition. SOLUTION: This bearing is prepared by prelubricating a bearing with a grease containing 0.05-20wt.% organocopper compound. The organocopper compound is desirably copper stearate, copper naphthenate or copper dimethyldithiocarbamate. Although not particularly limited, the grease is desirably a synthetic oil selected among poly-α-olefin oils, alkyldiphenyl ethers and ester oils or a base oil prepared by mixing them and is more desirably one containing a thickening agent comprising a urea compound. Because the grease contains an organocopper compound, it can form an inert film on the transfer surface of a bearing in the initial stage of use to prevent the occurrence of abnormal peeling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease-enclosed bearing, and more particularly, to a grease-enclosed bearing for automotive electrical parts such as an alternator, an electromagnetic clutch, an idler pulley, and other auxiliary parts.

[0002]

2. Description of the Related Art In recent years, electronic components for automobiles have been developed for the purpose of saving resources and energy, and reducing the size of components.
There is a demand for a reduction in size and weight, as well as an increase in performance and output, and the reduction in output due to miniaturization is compensated for by increasing the speed.

For example, in the case of the alternator and the electromagnetic clutch, in order to reduce the size of the pulley as much as possible and to prevent a reduction in transmission efficiency, a large number of engagement grooves of the conductive belt are connected to the pulley and the tension of the belt is increased. Means are taken. For this reason, both high-speed rotation and high load are applied to the bearing supporting the pulley.

However, when conventional grease is used for a bearing to which both high-speed rotation and high load are applied as described above, unlike a peeling that occurs from the surface of a rolling surface or a surface layer, a peculiar peeling that occurs from a considerably deep portion (hereinafter, referred to as a special peeling). , "Abnormal peeling") is likely to occur.

Regarding the cause of the above-mentioned abnormal peeling, the inventors of the present application have reported that the vibration caused by the high-speed rotation of the pulley causes the mirror surface wear of the raceway surface, and the formation of a new surface thereby acts as a catalyst to decompose the grease. In order to elucidate the phenomenon that hydrogen generated at this time penetrates into steel and becomes brittle (hereinafter referred to as “hydrogen embrittlement phenomenon”), in order to prevent this, a so-called blackening treatment or the like is applied to the steel surface. A technique for performing the inactivation process described above was developed and disclosed (JP-A-2-190615).

As another solution, metal powders such as Cu and Zn and oxide powders such as FeO, Fe ₂ O ₃ , CuO and Cu ₂ O are used as powders for forming an inert film on the bearing rolling surface. , FeSO ₄ , Fe ₂ (SO ₄ ) ₃ , ZnSO
A technique for mixing a sulfide powder such as No. ₄ was developed and disclosed (JP-A-5-59384).

[0007]

According to the above method,
By preventing abnormal peeling, the service life of the bearing could be prolonged.However, the inclusion of inorganic substances such as metal powders, oxides, and sulfides increased bearing noise and unstable bearing torque. Has become a bad effect.

[0008] Further, as another solution, an aromatic diurea compound or an aromatic urea-urethane compound is blended with a base oil in which an alkyl diphenyl ether oil and a poly-α-olefin oil are blended at a predetermined ratio. A grease to which a oxidizing agent and an organic sulfonic acid are added has been disclosed (JP-A-5-263091).

According to this method, abnormal peeling can be prevented,
Longer life of the bearing can be achieved. However, the use conditions of recent electrical and auxiliary bearings have become increasingly severe, and there has been a demand for bearings that are more resistant to abnormal peeling.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bearing which has low bearing noise, provides stable bearing torque, and has excellent abnormal peeling resistance.

[0011]

In order to solve the above-mentioned problems, the present invention relates to a grease-filled bearing in which a grease composition is sealed in a bearing, wherein the grease composition contains 0.1 g of an organic copper-based compound in grease. It was added in an amount of 0.5 to 20% by weight.

Further, the organic copper compound can be selected from copper stearate, copper naphthene, and copper dimethyldithiocarbamate. Further, as the grease, poly-α-olefin oil, alkyl diphenyl ether oil,
Alternatively, a synthetic oil selected from ester oils alone or a mixture thereof may be used, and a base oil containing a thickening agent composed of a urea compound may be used.

Since a grease containing an organic copper compound added to grease is used as a grease composition to be sealed in a bearing,
An inert film is formed on the rolling surface of the bearing at the beginning of use. For this reason, occurrence of abnormal peeling can be prevented. In addition, since the inert film is smooth, bearing noise can be reduced and a stable bearing torque can be obtained.

[0014]

Embodiments of the present invention will be described below. The bearing according to the present invention is a grease-enclosed bearing in which a grease composition is encapsulated in a bearing. This bearing is not particularly limited as long as it is a grease-sealed bearing, but it is a high-speed rotating and high-load bearing, such as alternators, electromagnetic clutches, idler pulleys, and other automotive electrical components and other auxiliary components. Rolling bearings, sliding bearings, etc. used for applications.

The grease composition is obtained by adding 0.05 to 20% by weight of an organic copper compound to grease.
The grease is not particularly limited, for example, poly-α-olefin oil, alkyl diphenyl ether oil, or a synthetic oil selected from ester oil alone or a base oil obtained by mixing these, and a urea compound Those containing a thickener consisting of

The poly-α-olefin oil is a synthetic oil having a structure in which an α-olefin is low-polymerized and hydrogen is added to a terminal double bond, and is represented by the following formulas (1) to (4). Can be exemplified.

[0017]

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(Wherein R ₁ , R ₂ and R ₃ are C _n H _{2n + 1}
(N is an integer of 6 to 14). )

[0019]

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(Wherein m represents an integer of 1 to 6, and R is
C _n H _{2n +} 1 _(n is 6 to 14 integer) representing the. )

[0021]

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(In the formula, p represents an integer of 1 to 6.)

[0023]

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(Where x and y are integers from 1 to 6;
Represents an integer of 3 to 30, and R ′ is C _n H _{2n + 1} (n is 1
-8). The above-mentioned alkyl diphenyl ether oil comprises 1 mol of diphenyl ether and an α-olefin having 10 to 22 carbon atoms.
It is a synthetic oil obtained by a molar addition reaction. Examples of the alkyl diphenyl ether oil include those represented by the following formula (5).

[0025]

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(In the formula, R ₄ is a linear alkyl group, and is bonded to an aromatic group as follows.)

[0027]

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Q + r of the alkyl group represents an integer of 9 to 15. The above-mentioned ester oil is a synthetic oil having an ester group in the molecule, such as a diester oil or an ester oil having 3 to 6 ester groups in the molecule.
And polyol ester oils. The terminal of this polyol ester oil has the following structure:

[0029]

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(Wherein R ₅ , R ₆ and R ₇ are C _n H _{2n + 1}
(N is an integer of 1 to 8). Examples of such polyol ester oils include trimethylolpropane ester and pentaerythritol ester.

These synthetic oils selected from poly-α-olefin oils, alkyl diphenyl ether oils and ester oils can be used alone as base oils. Further, these can be mixed at an arbitrary ratio, and the mixed oil can be used as a base oil. As the combination of the mixed oil, a combination of a poly-α-olefin oil and an alkyl diphenyl ether, a poly-α-olefin oil is desirable,
When the base oil is a mixed oil of a poly-α-olefin oil and an alkyl diphenyl ether oil, these are used in a ratio of 80:20.
To 20:80. Within this range, the performance at low temperatures is good and the heat resistance is maintained. When the base oil is a mixed oil of a poly-α-olefin oil and an ester oil, these are mixed in a ratio of 50:50 to 9:50.
It is preferable to mix them in a ratio of 0:10. Within this range, both performance at low temperatures and heat resistance are maintained.

The kinematic viscosity of the base oil is not particularly limited, but is preferably 30 to 100 mm ² / s at 40 ° C., more preferably 50 to 80 mm ² / s. Within this range, the agitation resistance of the grease becomes extremely small even under the conditions of high-speed and high-load bearings accompanying the further miniaturization of the alternator, etc. Grease that can prevent damage due to seizure, and can contribute to prolonging the durability life of the bearing under high speed and high load.

The urea compound used for the thickener comprising the urea compound has a urea bond (—NHCO)
A compound represented by the following formula 8 having two NH-) or a compound represented by the following formula 9 having both a urea bond (-NHCONH-) and a urethane bond (-NHCOO-) in the molecule. is there.

[0034]

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Wherein R ₈ is an aromatic hydrocarbon group having 7 to 13 carbon atoms, R ₉ and R ₁₀ are an aromatic hydrocarbon group or an alkyl group having 8 to 20 carbon atoms, and R ₉ or R ₁₀ At least one is an aromatic hydrocarbon group.)

[0036]

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(Wherein, R ₁₁ represents an aromatic hydrocarbon group having 7 to 13 carbon atoms, R ₁₂ and R ₁₃ represent an aromatic hydrocarbon group or an alkyl group having 8 to 20 carbon atoms, and R ₁₂ or R ₁₃ At least one is an aromatic hydrocarbon group.).

The urea compound represented by Chemical formula 8 can be obtained by blending a monoamine and an aromatic diisocyanate with the above-mentioned base oil as a solvent in the grease production step, and finely precipitating the same in the base oil. The urea compound represented by Chemical formula 9 can be obtained by reacting an isocyanate with an alcohol or an amine using toluene or a base oil as a solvent and precipitating the same in the base oil or toluene. The amount of such a urea compound to be added to the base oil is 5 to 40% by weight. If it is less than 5% by weight, the viscosity becomes poor, and
If the content is more than 10% by weight, it becomes solid and becomes unsuitable.

Examples of the organic copper-based compound include copper stearate (see the following chemical formula 10), naphthenic copper, copper dimethyldithiocarbamate (see the following chemical formula 11), and the like.

[0040]

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[0041]

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In addition, the same effect can be expected with an organic acid salt, alkoxide or chelate compound of copper.
Further, a plurality of compounds may be added as long as they are not reactive with each other.

The addition amount of the organic copper compound is 0.05 to 2
0% by weight is preferred. If the content is less than 0.05% by weight, an inert film is not easily formed on the rolling surface of the bearing, and it is difficult to prevent the occurrence of peeling. On the other hand, if the content exceeds 20% by weight, the oil content in the grease is reduced, so that the grease is hardened and lubricity is impaired.

[0044]

EXAMPLES Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. First, the materials used in the examples are shown below. (1) Base oil 1: Polyol ester oil (Ciba Geigy: Leolube LPE602) 2: Poly-α-olefin oil (Nippon Steel Chemical: Synfluid 801) 3: Alkyl diphenyl ether oil (Matsumura Chemical: Mole) (Scohylube LB-100) (2) Thickener 1: Mix alicyclic diurea mylionate MT (manufactured by Nippon Polyurethane Co., Ltd.) and cyclohexylamine (manufactured by Wako Pure Chemical Industries, Ltd.).
React at 130 ° C. for 30 minutes. 2: Aromatic diurea mylionate MT (manufactured by Nippon Polyurethane Co., Ltd.) and aniline (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed and reacted at 120 to 130 ° C. for 30 minutes. (3) Organic copper compounds 1: Copper stearate (Kanto Chemical Co .: Copper (II) stearate) 2: Copper naphthenate (Kanto Chemical Co .: Copper naphthenate) 3: Copper dimethyldithiocarbamate (Ouchi Emerging (4) Antioxidant 1: α-phenylnaphthylamine [hereinafter referred to as “PAN”. (Ouchi Shinko Chemical Co., Ltd .: Nocrack P
A).

Examples 1 to 5 A grease comprising 84% by weight of a polyol ester as a base oil and 14% by weight of an alicyclic diurea as a thickener (base oil viscosity at 40 ° C .: 32
mm ² / s) and ² % by weight of PAN as an antioxidant, copper stearate powder (average particle size: 10 μm
The following grease was added in an amount of 0.05 to 10% by weight based on the entire grease. 1.4 g of the obtained grease composition was sealed in a deep groove ball bearing (with a resin retainer) having an inner diameter of 17 mm, an outer diameter of 47 mm and a width of 14 mm with a contact rubber seal. Using this bearing, a life test was performed according to the following method. Table 1 shows the results. In Table 1, the content (%) of the base oil and the thickener is 100% of the entire grease.
Represents the content (% by weight) of each of the base oil and the thickener contained in this grease, and the addition amount (%) of the organic copper-based compound is expressed by the amount of the organic copper based on the grease amount of 100% by weight. Indicates the amount (% by weight) of the system compound added.

Life test The above deep groove ball bearing (with a resin cage) in which the grease composition was sealed was subjected to a bearing outer ring temperature of 60 to 80 ° C. and a radial load of 32.
The test was performed under the conditions of 30 N and a rotation speed of 18,000 rpm, and the operation time until the bearing was seized was measured. Experiments show the average value of the five above bearings. Those which did not cause seizure in 500 hours were cut off in 500 hours. After completion of the test, the state of the bearing was observed, and the presence or absence of peeling and the presence or absence of structural change were confirmed. Further, after the test was completed, the load area of the fixed wheel was cut in the circumferential direction, and changes in the metal structure were observed with an optical microscope.

[Examples 6 to 10] Copper naphthenate powder (average particle size: 10) based on the grease used in Example 1
0.05 μm or less) was added. 1.4 g of the obtained grease composition was sealed in the bearing described in Example 1. Using this bearing, a life test was performed in accordance with the above method. Table 1 shows the results.

Examples 11 to 15 Based on the grease used in Example 1, 0.05 to 10% by weight of copper dimethyldithiocarbamate powder (average particle size: 10 μm or less)
Was added. 1.4 g of the obtained grease composition was sealed in the bearing described in Example 1. Using this bearing, a life test was performed in accordance with the above method. Table 1 shows the results.

Examples 16-18 Poly-α as base oil
A grease (base oil viscosity at 40 ° C .: 72 mm ² / s) comprising 20% by weight of an olefin oil and 80% by weight of an alkyl diphenyl ether oil and 20% by weight of an aromatic diurea as a thickener; Copper stearate powder (average particle size: 10 μm or less)
10% by weight was added. 1.4 g of the obtained grease composition
Was sealed in the bearing described in Example 1. Using this bearing, a life test was performed in accordance with the above method. Table 2 shows the results. In Table 2, the content (%) of each base oil and thickener is the content (% by weight) of each base oil and thickener contained in this grease, assuming that the entire grease is 100%. And the addition amount (%) of the organic copper-based compound represents the addition amount (% by weight) of the organic copper-based compound when the amount of grease is 100% by weight.

[Examples 19 to 21] Copper naphthenate powder (average particle size: based on the grease used in Example 16)
(Less than 10 μm). 1.4 g of the obtained grease composition was sealed in the bearing described in Example 1. Using this bearing, a life test was performed in accordance with the above method. Table 2 shows the results.

[Examples 22 to 24] Based on the grease used in Example 16, 0.05 to 10% by weight of copper dimethyldithiocarbamate powder (average particle size: 10 µm or less) was added. 1.4 g of the obtained grease composition was sealed in the bearing described in Example 1. Using this bearing, a life test was performed in accordance with the above method. Table 2 shows the results.
Shown in

Comparative Example 1 A grease having a base oil composed of a polyol ester and a thickener composed of an alicyclic diurea shown in Table 2 (base oil viscosity at 40 ° C .: 32 mm ²
/ S) 1.4 g were sealed in the bearing described in Example 1.
Using this bearing, a life test was performed in accordance with the above method. Table 2 shows the results.

Comparative Example 2 A grease having a base oil composed of a poly-α-olefin oil and an alkyl diphenyl ether oil and a thickener composed of an aromatic diurea shown in Table 2 (base oil viscosity at 40 ° C .: 72 mm ² / s) 1.4 g
Was sealed in the bearing described in Example 1. Using this bearing, a life test was performed in accordance with the above method. Table 2 shows the results.

[0054]

[Table 1]

[0055]

[Table 2]

Results As is clear from Table 1, it was revealed that the use of the organocopper-based compound of the present invention endured a life test of 500 hours, did not cause peeling, and did not cause structural change.

[0057]

According to the present invention, since an organocopper-based compound is added to grease, an inert film is formed on the rolling surface of the bearing in the early stage of use, and abnormal peeling is prevented.

Further, since the inert coating is smooth, bearing noise can be reduced and a stable bearing torque can be obtained.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 115: 08 129: 38 135: 18) C10N 10:02 40:02 50:10

Claims (3)

[Claims] 1. A grease-filled bearing in which a grease composition is sealed in a bearing, wherein the grease composition is obtained by adding 0.05 to 20% by weight of an organic copper compound to grease. 2. The grease-enclosed bearing according to claim 1, wherein the organic copper-based compound is selected from copper stearate, copper naphthene, and copper dimethyldithiocarbamate. 3. The grease contains a synthetic oil selected from poly-α-olefin oils, alkyl diphenyl ether oils, or ester oils, alone or in combination, and a thickener comprising a urea compound. The grease-enclosed bearing according to claim 1 or 2, wherein