JP2001323293A - Oil-impregnated bearing and lubricating oil used for the bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the rotating accuracy and also endurance of a bearing by impregnating oil having a good lubricating property to the bearing to reduce the shake of the rotating shaft of a motor. SOLUTION: This lubricating agent is obtained by adding a fatty acid metal salt and further at least 1 kind among phosphoric acid esters or their amine salts and a sulfur-based ultrahigh pressure agent, and a (sintered) oil-impregnated bearing is obtained by impregnating the above agent to the bearing. Thereby, it is possible to obtain the bearing excellent in the rotating slid lubricating property of a motor shaft against the bearing, improving the endurance to make the shake of the shaft almost none, also lessening sliding resistance to get a good rotating accuracy, suitable for a driving source for a highly functional motor such as a scanner motor for an LBP or a spindle motor for an AV gear, improving the endurance and reliability of the motor and capable of aiming at high quality such as the reduction of its maintenance cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an LBP scanner motor, a DC main motor, a DC brushless motor,
Alternatively, a spindle motor for AV equipment, a spindle motor for HDD, and the like, in particular, a medium relief type (sintering) in which a large-diameter hollow portion that does not come into contact with the shaft material is formed in the middle portion of the inner diameter surface to be fitted in the housing. ) Regarding the improvement of an oil-impregnated bearing and a lubricating oil to be used by being impregnated in the bearing, the rotation shaft of the motor is reduced to improve the rotation accuracy, and the durability and the shaft loss (sliding resistance) are reduced. In particular, as a highly functional motor drive source for the above AV and various information devices, etc., it has improved durability and reliability,
Moreover, the object is to achieve high quality such as reduction of maintenance cost.

[0002]

2. Description of the Related Art In recent years, in order to improve the accuracy of a motor, a metal powder is compacted and sintered, and a lubricating oil is impregnated inside the bearing in many cases. Above all, in the case of spindle type motors used in AV equipment, etc., the frictional resistance (axis loss) between the rotating shaft and the bearing is reduced,
In order to suppress the temperature rise during continuous rotation, for example, a bearing unit having a large-diameter portion formed at the center of the inner peripheral surface (Japanese Patent Laid-Open No. 11-294457), What uses a so-called "middle relief type" bearing, such as one having a relief that does not contact (Japanese Patent Publication No. 8-6124), has become mainstream.

[0003] Further, the above-mentioned medium relief type oil-impregnated bearing includes a general-purpose base oil such as mineral oil or synthetic oil as a lubricating oil, and an extreme pressure agent such as zinc alkyldithiophosphate (Zn-DTP) or chlorinated paraffin. In many cases, oily agents such as alcohols, fatty acids and fatty acid esters are added, or only antioxidants and rust inhibitors are added.

[0004]

However, most of the spindle motors using these intermediate relief bearings are, for example, VTRs, DVD-ROMs or CD-ROMs.
Because it is used for driving high-precision and high-quality equipment such as disk drives, even a slight wear of the bearing is likely to cause shaft runout, and the rotation accuracy deteriorates quickly, so the motor itself must be replaced each time. There is a need, and improvement is desired from the viewpoint of economy and maintenance.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems in the prior art, and in particular, eliminates abrasion on the inner surface of the bearing and provides a highly functional motor drive source for AV and various information equipment. It is intended to improve the durability and reliability with high accuracy and to reduce the maintenance cost. Basically, the invention of claim 1 is characterized in that a fatty acid metal salt is added to a base oil, The present invention relates to an oil-impregnated bearing characterized by being impregnated with a lubricating oil obtained by adding at least one of a phosphate ester or an amine salt thereof and a sulfur-based extreme pressure agent thereto. In this case, a sintered type is preferably used as the oil-impregnated bearing.

According to a thirteenth aspect of the present invention, in the first aspect, a fatty acid metal salt and at least one of a phosphate ester or an amine salt thereof and a sulfur-based extreme pressure agent are added to the base oil. Claims 1 to 1 including the invention of claim 1
2. A lubricating oil used in the oil-impregnated bearing described in 2.

When a fatty acid metal salt and at least one of a phosphate ester or an amine salt thereof and a sulfur-based extreme pressure agent are added to the base oil of the lubricating oil impregnated in the bearing, the lubricating oil It dissolves or disperses uniformly in the base oil to exhibit lubrication characteristics with excellent extreme pressure properties, and also significantly improves abrasion resistance to the rotating shaft.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents of the present invention will be described below with reference to an embodiment in which the present invention is applied to a middle relief type motor bearing shown in FIG. The bearing is press-fitted into the inner surface 2 of the cylinder. Further, the bearing 3 has a shaft hole 4 which is large enough to receive metal powder such as copper into the housing holder 1 and which can support a motor shaft (not shown). After being compacted so as to have a large-diameter middle relief portion 5 in the middle of 4, it is formed by sintering, and the sintered body is impregnated with oil to form a bearing.

The lubricating oil impregnated in the bearing 3 sintered as described above will be described below. First of all, the base oil of the lubricating oil is not particularly limited as long as it is widely used as the base oil of general-purpose equipment oil.
Either mineral oil or synthetic oil can be used.

[0010] As the mineral oil, for example, a distillate obtained by subjecting a paraffin-based crude oil, an intermediate-based crude oil or a naphthenic-based crude oil to atmospheric distillation, or a residual oil obtained by atmospheric distillation under reduced pressure, or Refined oil obtained by refining according to a conventional method, for example, solvent refined oil, hydrogenated refined oil,
Dewaxing treatment oil, terra alba treatment oil, and the like. Among them, the above-mentioned highly refined mineral oil is excellent in terms of antioxidant life, thermal stability (anti-sludge deposition property), and temperature / viscosity characteristics.

Examples of synthetic oils include poly-α-olefin (PAO), α-olefin copolymer, polybutene, polyisobutylene, alkylbenzene, polyol ester, dibasic acid ester, polyoxyalkylene glycol, polyoxyalkylene glycol ester,
Examples thereof include polyoxyalkylene glycol ether, aromatic ester, hindered ester, silicone oil, polycarbonate, and polyvinyl ether. Among them, poly-α-olefin (PAO) is more preferred in terms of thermal stability, antioxidant life, temperature / viscosity characteristics, water resistance, and low irritation to resins.

The above-mentioned various base oils can be used alone or in combination of two or more, and a combination of a mineral oil type and a synthetic oil type is also possible.

Furthermore the viscosity of the base oil to be used, in order to maintain good lubricating properties, preferably kinematic viscosity 2~4,600mm ² / S at 40 ° C., more preferably from 2 to 100 mm ² / S, Particularly preferably, 2-68
mm ² / S.

Further, the fatty acid metal salt to be added to the base oil includes those represented by the following general formula (1). (R ₁ -coo) n Mx (1) (Mx is Na, Mg, Al, K, Ca, Li, Ti,
Elements such as Mn, Fe, Co, Ni, Cu, Zn and the like. n is an integer of 1 to 3. Further, R ₁ has 4 to 30 carbon atoms.
Represents an alkyl group, an alkylaryl group, an alkenyl group, and an arylalkyl group. )

Of these, the use of Mg, Al and Zn is preferred. If the amount of the fatty acid metal salt added exceeds 10% (by weight), the apparent viscosity becomes too high, which may lead to a loss in stirring.
If it is less than 01 (weight)%, the friction characteristics tend to be insufficiently improved. Therefore, 0.01 to 10.0 (weight)
%, And particularly preferably in the range of 0.05 to 5.0 (weight)%.

Further, phosphate esters blended in the base oil together with the above-mentioned fatty acid metal salts can be used to improve the wear resistance, friction coefficient and sludge resistance of the bearings by the following general formulas (2) to (2). The phosphoric acid ester, acidic phosphoric acid ester, phosphite and acidic phosphite represented by 6) are included.

[0017]

[0018]

[0019]

[0020]

[0021]

In the above general formulas (2) to (6),
R ^{1 to} R ³ represent an alkyl group, an alkenyl group, an alkylaryl group and an arylalkyl group having 4 to 30 carbon atoms, and R ^{1 to} R ³ may be the same or different.

Examples of the phosphoric acid ester include triaryl phosphate, trialkyl phosphate, trialkylaryl phosphate, triarylalkyl phosphate, trialkenyl phosphate and the like. Specifically, for example, triphenyl phosphate, tricresyl phosphate, benzyl Diphenyl phosphate, ethyl diphenyl phosphate, tributyl phosphate, ethyl dibutyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, ethyl phenyl diphenyl phosphate, diethyl phenyl phenyl phosphate, propyl phenyl diphenyl phosphate, dipropyl phenyl phenyl phosphate, triethyl phenyl phosphate, Tripropyl phenyl phosphate, spot Phenyl diphenyl phosphate,
Dibutyl phenyl phenyl phosphate, tributyl phenyl phosphate, trihexyl phosphate, tri (2-ethylhexyl) phosphate, tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tripalmityl phosphate, tristearyl phosphate, trioleyl phosphate and the like can be mentioned. it can.

Examples of the acidic phosphate include, for example, 2-ethylhexyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate, and the like. Tridecyl acid phosphate, stearyl acid phosphate,
Isostearyl acid phosphate and the like can be mentioned.

Further, as the phosphite, specifically, for example, triethyl phosphite, tributyl phosphite, triphenyl phosphite, tricresyl phosphite, tri (nonylphenyl) phosphite, tri (2-ethylhexyl) Examples include phosphite, tridecyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphenylisodecyl phosphite, tristearyl phosphite, and trioleyl phosphite.

Specific examples of the acidic phosphite include dibutyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, distearyl hydrogen phosphite, and diphenyl hydrogen phosphite. it can. Among the general formula (6), those represented by the following general formula (7) are more preferably used.

(R ¹ O) ₂ POH (7) (wherein, R ¹ represents an alkyl group or an alkenyl group each having 12 to 30 carbon atoms.)

In the general formula (7), R ¹ is preferably an alkyl group or an alkenyl group having 12 to 30 carbon atoms. The number of carbon atoms of R ¹ in the acidic phosphite ester is of less than 12 poor stability, it tends to occur a sludge. Those having more than 30 carbon atoms have little effect on lubricating properties and the like, and are difficult to obtain. From such a point, R ¹
Is preferably 12 to 22 carbon atoms.

Examples of the acidic phosphite used in the present invention include dilauryl hydrogen phosphite, dipalmityl hydrogen phosphite, distearyl hydrogen phosphite, and dioleyl hydrogen phosphite. Particularly preferred is dioleyl hydrogen phosphite.

Among the various phosphoric esters described above,
Above all, tricresyl phosphate, oleyl acid phosphate, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite are wear resistant,
Excellent in low coefficient of friction, sludge deposition resistance, etc.

Further, examples of the amines forming an amine salt with these include a mono-substituted amine, a di-substituted amine and a tri-substituted amine represented by the following general formula (8).

R ⁴ _n NH _3-n (8) (wherein, R ⁴ is an alkyl group or alkenyl group having 3 to 30 carbon atoms, an aryl group or arylalkyl group having 6 to 30 carbon atoms, or carbon number) And represents 2 to 30 hydroxyalkyl groups, and n represents 1, 2 or 3. R ⁴
When there are two or more, several R < ⁴ > may be the same or different. The alkyl group or alkenyl group having 3 to 30 carbon atoms in R ^{4 in} the formula may be linear, branched, or cyclic. )

Here, examples of the monosubstituted amine include:
Butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, laurylamine,
Examples include stearylamine, oleylamine, and benzylamine.Examples of disubstituted amines include dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, distearylamine, dioleylamine, Examples thereof include benzylamine, stearyl monoethanolamine, decyl monoethanolamine, hexyl monopropanolamine, benzyl monoethanolamine, phenyl monoethanolamine, and tolyl monopropanol.

Examples of the tri-substituted amine include tributylamine, tripentylamine, trihexylamine, tricyclohexylamine, trioctylamine,
Trilaurylamine, tristearylamine, trioleylamine, tribenzylamine, dioleyl monoethanolamine, dilauryl monopropanolamine, dioctyl monoethanolamine, dihexyl
Monopropanolamine, dibutyl monopropanolamine, oleyl diethanolamine, stearyl
Examples thereof include dipropanolamine, lauryl diethanolamine, octyl dipropanolamine, butyl diethanolamine, benzyl diethanolamine, phenyl diethanolamine, tolyl dipropanolamine, xylyl diethanolamine, triethanolamine, and tripropanolamine.

The above-mentioned various phosphoric esters or amine salts thereof may be used alone or in combination of two or more. In addition, about those compounding quantity,
If the amount is less than 0.01% by weight based on the total amount of the composition, the improvement in frictional characteristics due to the synergistic effect with other components such as fatty acid metal salts tends to be insufficient, and the amount exceeds 10% by weight. There is no sufficient effect corresponding to the above. Therefore, the content is preferably in the range of 0.01 to 10.0 (weight)%, and more preferably in the range of 0.05 to 5.0.

Next, the sulfur type extreme pressure agent will be described.
Sulfur-based extreme pressure agents have sulfur atoms in their molecules, dissolve or disperse uniformly in lubricating base oils, and exhibit extreme pressure properties and excellent friction properties due to the synergistic effect with the fatty acid metal salts described above. Things are used. Examples of such a substance include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfide, thiadiazole compounds, alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, and dialkylthiodipropionate compounds. it can.

Here, the sulfurized oil and fat is obtained by reacting sulfur or a sulfur-containing compound with an oil or fat (lard oil, whale oil, vegetable oil, fish oil, etc.), and the sulfur content is not particularly limited. Generally, the use of 5 to 30% by weight is preferred. Specific examples thereof include sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, sulfurized soybean oil, and sulfurized rice bran oil. Examples of the sulfurized fatty acid include sulfurized oleic acid and the like, and examples of the sulfurized ester include methyl sulfated oleate and sulfide of rice bran fatty acid octyl.

Further, as the sulfurized olefin, for example, the following general formula (9): R ⁵ -S ^a -R ⁶ (9) (wherein, R ⁵ is an alkenyl group having 2 to 15 carbon atoms, R ⁶ Represents an alkyl group or an alkenyl group having 2 to 15 carbon atoms, and a represents an integer of 1 to 8).

This compound is obtained by reacting an olefin having 2 to 15 carbon atoms or a di- to tetramer thereof with a sulfurizing agent such as sulfur or sulfur chloride. Examples of the olefin include propylene, isobutene, diisobutene and the like. Is preferred.

Further, the dihydrocarbyl polysulfide is a compound represented by the following general formula _{^{(10) R 7 -S b -R}} 8 ............ (10) ( wherein, ^{R 7} and ^{R 8,} C 1-20 carbon respectively An alkyl group or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms, which may be the same or different from each other , B represents an integer of 1 to 8). Here, when R ⁷ and R ⁸ are alkyl groups, they are referred to as “alkyl sulfide”.

Specific examples of R ⁷ and R ⁸ in the general formula (10) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert group. -Butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups,
Examples thereof include a cyclohexyl group, a cyclooctyl group, a phenyl group, a naphthyl group, a tolyl group, a xylyl group, a benzyl group, and a phenethyl group.

Preferred examples of the above-mentioned dihydrocarbyl polysulfide include dibenzyl polysulfide, various dinonyl polysulfides, various didodecyl polysulfides, various dibutyl polysulfides,
Various dioctyl polysulfides, diphenyl polysulfides, dicyclohexyl polysulfides and the like can be mentioned.

As the thiadiazole compound, for example, the following general formula (11)

[0044]

(Wherein R ⁹ and R ¹⁰ each represent a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, and c and d each represent an integer of 0 to 8). , 3,4-thiadiazole, 1,2,4-thiadiazole compounds, 1,4,5-thiadiazole and the like are preferably used.

Preferred specific examples of such a thiadiazole compound include 2,5-bis (n-hexyldithio) -1,3,4-thiadiazole and 2,5-bis (n
-Octyldithio) -1,3,4-thiadiazole,
2,5-bis (n-nonyldithio) -1,3,4-thiadiazole, 2,5-bis (1,1,3,3-tetramethylbutyldithio) -1,3,4-thiadiazole,
3,5-bis (n-hexyldithio) -1,2,4-thiadiazole, 3,5-bis (n-octyldithio)-
1,2,4-thiadiazole, 3,5-bis (n-nonyldithio) -1,2,4-thiadiazole, 3,5-bis (1,1,3,3-tetramethylbutyldi)-
1,2,4-thiadiazole, 4,5-bis (n-hexyldithio) -1,2,3-thiadiazole, 4,5-
Bis (n-octyldithio) -1,2,3-thiadiazole, 4,5-bis (n-nonyldithio) -1,2,3
-Thiadiazole, 4,5-bis (1,1,3,3,-
(Tetramethylbutyldi) -1,2,3-thiadiazole and the like.

Examples of the alkylthiocarbamoyl compound include those represented by the following general formula (12).

[0048]

(In the formula, R ^{11 to} R ¹⁴ each represent an alkyl group having 1 to 20 carbon atoms, and e represents an integer of 1 to 8.) Preferred specific examples of such an alkylthiocarbamoyl compound include: Bis (dimethylthiocarbamoyl) monosulfide, bis (dibutylthiocarbamoyl) monosulfide, bis (dimethylthiocarbamoyl) disulfide, bis (dibutylthiocarbamoyl) disulfide, bis (diamylthiocarbamoyl) disulfide,
Bis (dioctylthiocarbamoyl) disulfide and the like can be mentioned.

Preferred examples of the thioterpene compound include a reaction product of phosphorus pentasulfide and pinene, and examples of the dialkylthiodipropionate compound include dilauryl thiodipropionate and distearyl thiodipropionate. And the like. Among the various substances described above, sulfur oils, thiadiazole compounds, and benzyl sulfide are particularly excellent in terms of extreme pressure properties, friction characteristics, thermal oxidative stability, and the like.

In the present invention, the various sulfur-based extreme pressure agents described above may be used alone or in combination of two or more. In addition, their blending amounts are also 0.01 (weight) based on the total amount of the composition.
If the content is less than 10% by weight, the improvement of the coefficient of friction due to the synergistic effect with other components such as fatty acid metal salts tends to be insufficient, and even if the content exceeds 10% by weight,
The effect corresponding to the content may not be improved.
Therefore, the amount of the sulfur-based extreme pressure agent in this case is 0.01 to 10.0 based on the total amount of the composition.
(% By weight) is preferable, and more preferably 0.05 to 5.0.
It is concluded that the (weight)% range is even more preferred.

The lubricating oil impregnated in the sintered oil-impregnated bearing of the present invention may optionally contain an antioxidant. As the antioxidant used herein, among the components of the antioxidant, as the amine antioxidant, for example, monooctyldiphenylamine; monoalkyldiphenylamine such as monononyldiphenylamine;
4,4'-dibutyldiphenylamine;4,4'-dibenzyldiphenylamine;4,4'-dihexyldiphenylamine;4,4'-diheptyldiphenylamine;
4,4'-dioctyldiphenylamine; dialkyldiphenylamines such as 4,4'-dinonyldiphenylamine;tetrabutyldiphenylamine;tetrahexyldiphenylamine;tetraoctyldiphenylamine; polyalkyldiphenylamines such as tetranonyldiphenylamine; α-naphthylamine; phenyl-
α-naphthylamine; butylphenyl-α-naphthylamine; benzylphenyl-α-naphthylamine; hexylphenyl-α-naphthylamine; heptylphenyl α
Naphthylamine; octylphenyl-α-naphthylamine; and naphthylamine-based ones such as nonylphenyl-α-naphthylamine.

Of the above-mentioned antioxidants, dialkyldiphenylamine-based and naphthylamine-based ones are more preferable in view of antioxidative life. The above-mentioned amine antioxidants may be used alone or in combination of two or more.

Among the above antioxidants, phenolic antioxidants include, for example, 2,6-di-ter
t-butyl-4-methylphenol; 2,6-di-te
rt-butyl-4-ethylphenol, 2,6-di-t
tert-butyl-4- {4,6-bis (octylthio)
Monophenols such as -1,3,5-triazin-2-ylamino} phenol, 4,4′-methylenebis (2,6-di-tert-butylphenol); 2,2
Examples thereof include diphenol-based compounds such as' -methylenebis (4-ethyl-6-tert-butylphenol), each of which may be used alone or in combination of two or more. They may be used in combination.

The preferred amounts of the amine-based antioxidant and the phenol-based antioxidant of the above-mentioned antioxidant components are 0.01 to 5.0 based on the total amount of each composition.
0% by weight, and more preferably 0.03% by weight.
~ 3.0 (weight)%.

Further, the lubricating oil composition impregnated in the sintered oil-impregnated bearing of the present invention may contain, if necessary, a known demulsifier, a rust preventive, a metal deactivator, a cleaning dispersant, a defoamer and the like. The various additives described above can be appropriately compounded within a range that does not hinder each purpose. Incidentally, examples of the demulsifier include polyalkylene glycols and metal sulfonates. Among them, use of an EO / PO block copolymer having both ends OH is preferable.

Examples of the rust preventive include metal sulfonates, carboxylic acids, alkanolamines, amides, acid amides, and metal salts of phosphoric acid esters.
Of these, the use of carboxylic acids is preferred. Further, as the metal deactivator, benzotriazole and the like, and as the detergent and dispersant, metal sulfonates, metal phenates, metal salicylates, metal phosphonates, succinimides, acid amides, and the like. Examples thereof include methyl silicone, fluorosilicone, and polyacrylate, and among them, methyl silicone is particularly preferable.

As to the method of impregnating the bearing with the lubricating oil, the sintered metal body may be immersed in the oil for a certain period of time or impregnated by applying pressure.

[Test Example] The results of a test conducted on the friction characteristics of the oil-impregnated lubricating oil containing an aliphatic metal salt during poor lubrication are shown below. The test method was based on a Falex friction / wear test, and the seizure resistance was evaluated during poor lubrication. A bearing impregnated with lubricating oil is a mechanical element that performs lubrication between the rotating shaft and the bearing with a very small amount of impregnating oil. Therefore, unlike a general machine element, the oil agent used in such a case tends to be poorly lubricated because the amount is very small.

Therefore, in order to reproduce such poor lubrication conditions, the test lubricant is applied to the pin by observing the pin as the rotating shaft and the V block as the bearing material in accordance with the Falex friction and wear test method. Therefore, it was decided to evaluate the friction characteristics during poor lubrication.

The details of the test conditions are as follows. That is, a Falex friction and abrasion tester: ASTM D 3233-93 (evaluation of extreme pressure properties) Test piece: pin AISI / SAE 3135 STEEL V block AISI 1137 STEEL Number of revolutions: 1800 rpm Load: 440N (100 lbs) Time to reach (seconds) Method of applying test lubricating oil to pins: After the pins have been completely immersed in the lubricating oil, pull up the pins and suspend the pins in a thermostat at 60 ° C for 30 minutes. The test was left in a state where a uniform oil film of the lubricating oil was formed on the surface. The test results are as shown in Table 1.

[Table 1]

[0063]

Table 2 shows the test results when dilauryl hydrogen phosphite was used instead of dioleyl hydrogen phosphite in [Table 1].

[Table 2]

As is evident from the results of Tables 1 and 2, lubricating oils (Examples 1 to 9) in which a phosphoric acid ester or a sulfur-based extreme pressure agent was added to a fatty acid metal salt and mixed were used. It can be seen that the lubricating properties (time to seizure-seizure resistance) are far superior to the lubricating oils used alone. This also means that a thick oil film is present on the surface even in poor lubrication, proving that anti-seizure, abrasion resistance, low friction, and the effect of suppressing the shaft runout due to the thick oil film can be expected.

In the above-described configuration, the motor shaft (not shown) is supported at both ends in the longitudinal direction of the shaft hole 4 in the bearing 3, and when the motor is used with time, the oil on the inner peripheral surface of the shaft hole 4 becomes insufficient. Then, the oil oozes from the inside of the porous bearing 3 to the inner peripheral surface of the shaft hole 4 and is successively supplied. A disk drive turntable (not shown) for mounting a rotating medium such as a CD-ROM disk or a fan is mounted on the front end of the motor shaft.

[0068]

As described above, the present invention comprises adding a fatty acid metal salt to a base oil and further adding at least one of a phosphate ester or an amine salt thereof and a sulfur-based extreme pressure agent to the base oil (sintering). ) Since it is a lubricating oil for an oil-impregnated bearing, and a (sintered) oil-impregnated bearing of a medium relief type impregnated with the lubricating oil, at least one of a phosphoric acid ester or an amine salt thereof and a sulfur-based extreme pressure agent is lubricating oil. Synergy with the fatty acid metal salt contained therein provides excellent rotational sliding lubrication of the motor shaft with respect to the bearing, and due to improved durability, there is almost no shaft runout and good rotational accuracy, especially for LBP Scanner motor, DC main motor, DC brushless motor,
Alternatively, it is suitable as a highly functional motor drive source such as a spindle motor for AV equipment and a spindle motor for HDD, and also as a drive source for various fan motors, thereby improving the durability and reliability of the motor and reducing maintenance costs. Quality can be improved.

As fatty acid metal salts added to the base oil, aluminum, cobalt, zinc, lithium, sodium,
When any one of calcium, potassium and titanium is used, it is particularly excellent in shaft runout prevention, lubrication (wear resistance, low friction coefficient), anti-oxidation life, etc., and therefore, in terms of durability and low power consumption. It is even more beneficial in

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a state in which a sintered oil-impregnated bearing according to an embodiment of the present invention is pressed into a housing holder of a brushless motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing holder 2 Cylindrical inner surface 3 Bearing 4 Shaft hole 5 Escape part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 135/06 C10M 135/06 135/18 135/18 135/20 135/20 135/36 135/36 137 / 02 137/02 137/04 137/04 137/08 137/08 F16C 33/10 F16C 33/10 A // C10N 10:02 C10N 10:02 10:04 10:04 10:06 10:06 10: 08 10:08 10:14 10:14 10:16 10:16 20:02 20:02 30:06 30:06 30:10 30:10 40:02 40:02 F-term (reference) 3J011 AA07 AA20 BA02 KA02 LA01 MA12 MA22 PA01 RA03 SB19 4H104 BB16C BC07C BG04C BG10C BG11C BG19C BH02C BH03C BH05C CA01A DA02A EA02A FA01 FA02 FA03 FA04 FA07 FA08 LA03 LA05 PA01

Claims (13)

[Claims] 1. A base oil impregnated with a metal salt of a fatty acid and a lubricating oil obtained by adding at least one of a phosphoric acid ester or an amine salt thereof and a sulfur-based extreme pressure agent to the base oil. Features oil-impregnated bearings. 2. A highly refined base oil obtained by distilling an intermediate base crude oil or a naphthenic base crude oil under normal pressure, or distillate obtained by vacuum distillation of a residual oil of normal pressure distillation according to a conventional method. The oil-impregnated bearing according to claim 1, wherein the oil-bearing is mineral oil. 3. The oil-impregnated bearing according to claim 1, wherein the base oil is a poly-α-olefin (synthetic oil). 4. A highly refined base oil obtained by distilling an intermediate base crude oil or a naphthenic base crude oil under normal pressure, or distillate obtained by distilling the residual oil of normal pressure distillation under reduced pressure according to a conventional method. The oil-impregnated bearing according to claim 1, wherein the poly-α-olefin (synthetic oil) is added to mineral oil. 5. The base oil viscosity of the impregnated lubricating oil is 2-4,
600 mm ² / S claim 1 which is where a (40 ° C.)
5. The oil-impregnated bearing according to 4. 6. The impregnated lubricating oil has a base oil viscosity of 2-68.
oil retaining bearing according to mm ² / S claims 1 to 4 where a (40 ° C.). 7. The oil-impregnated bearing according to claim 1, wherein the fatty acid metal salt added to the impregnated lubricating oil is Mg, Al, or Zn. 8. The oil-impregnated bearing according to claim 1, wherein the phosphates added to the impregnated lubricating oil are tricresyl phosphate, oleyl acid phosphate or acidic phosphite. 9. The compounding amount of one or more phosphate esters added to the impregnated lubricating oil is 0.01 to 10.3.
The oil-impregnated bearing according to any one of claims 1 to 8, wherein the content is 0 (weight)%. 10. The oil-impregnated bearing according to claim 1, wherein the sulfur-based extreme pressure agent added to the impregnated lubricating oil is a sulfurized oil or fat, a thiadiazole compound, or benzyl sulfide. 11. The compounding amount of one or more sulfur-based extreme pressure agents added to the impregnated lubricating oil is 0.01 to 10.0.
The oil-impregnated bearing according to any one of claims 1 to 10, wherein the weight is (% by weight). 12. The oil-impregnated bearing according to claim 1, wherein the bearing is a middle relief type having a large-diameter hollow portion that does not come into contact with the shaft material at an intermediate portion of the inner diameter surface. 13. A lubricating oil for an oil-impregnated bearing according to claim 1.