JP4814513B2 - Grease-filled rolling bearing - Google Patents

Description

  The present invention relates to a grease composition enclosed in a rolling bearing incorporated in various industrial machines and vehicles, and is particularly suitable for a bearing used at a high speed rotation in a wide temperature range from a very low temperature to a high temperature where abnormal noise is generated during cold. The present invention relates to a grease composition.

  A rolling bearing incorporated in various industrial machines, vehicles and the like is filled with a grease composition in order to impart lubricity. This grease composition is obtained by kneading a base oil and a thickener. Examples of the base oil include mineral oils, ester oils, silicone oils, ether oils, fluorine oils and other synthetic lubricating oils. Metal soaps such as lithium soap, urea compounds, and fluororesins are generally used. In recent years, rolling bearings tend to be used at high speed rotation, and accordingly, grease compositions are required to have high temperature resistance. However, when metal soap is used as a thickener, the oxidation of the base oil is promoted at a high temperature to lower the lubricating action. Regarding the base oil, a grease composition using a mineral oil as a base oil is more likely to be oxidized than a grease composition using a synthetic lubricating oil as a base oil, and the lubricating life at a high temperature tends to be shortened. In recent years, therefore, grease compositions using synthetic lubricants as base oils and urea compounds or fluororesins as thickeners are becoming mainstream in rolling bearings used at high temperatures and high speeds.

With the miniaturization and high performance of various industrial machine members, the usage conditions tend to become stricter. Accordingly, further lubrication performance and lubrication life are required for the grease composition.
The requirements for longer life at high temperatures are being studied for the addition of antioxidants and rust inhibitors to grease compositions based on synthetic lubricants with high viscosity and urea compounds as thickeners. As a result, the viscosity of the grease composition increases during cold weather, and noise during cold tends to occur.
On the other hand, when a pulley or the like of a device driven by an automobile engine is operated in cold weather, a singular sound (whispering noise) in cold weather, that is, a so-called cold noise may be generated depending on the pulley specifications and operating conditions. The cause of the generation of this cold abnormal noise has not yet been clearly clarified, but it is presumed to be due to the self-excited vibration of the rolling elements due to the oil film unevenness of the grease. In other words, when the oil is cold, unevenness of the oil film on the raceway surface is likely to occur due to an increase in the base oil viscosity of the grease, but if there is oil film unevenness, the friction coefficient between the rolling elements and the raceway surface will cause minute periodic changes. Causes self-excited vibration in the rolling element. It is considered that the pulley system resonates due to this self-excited vibration, and the outer ring vibrates in the axial direction (translational movement), resulting in generation of cold noise.

As a grease that has excellent high-temperature durability and suppresses abnormal noise during cold, 8 or more ester groups are arranged in a comb-teeth shape on one side of 8 or more carbon atoms that constitute the chain molecule of synthetic hydrocarbon oil and oil. A grease is known in which a urea compound is blended as a thickener and a dithiophosphate is added as an extreme pressure agent to a base oil composed of a mixed oil with an ester synthetic oil (Patent Document 1).
In addition, a base oil composed of a mixed oil of poly-α-olefin (hereinafter referred to as PAO) oil and ester oil is blended with an alicyclic diurea compound as a thickener, and zinc dithiocarbamate is added as an additive. A bearing encapsulating a composition, wherein a plurality of balls interposed between an inner ring constituting the bearing and an outer ring are brought into contact with the ball and at least the outer ring of the inner ring or the outer ring at two points. There is known a bearing for an automobile pulley to which is given (Patent Document 2).
Japanese Patent Laid-Open No. 9-208982 JP-A-11-270566

These attempts aimed at improving the stability of the oil film at low temperatures and prolonging the service life at high temperatures as a countermeasure against abnormal noise during cold, but it is sufficient to simply mix synthetic hydrocarbon oil and ester oil. There is a problem that the result of preventing abnormal cold noise is not obtained.
In addition, the usage conditions tend to become more severe with the miniaturization and higher performance of the various mechanical members listed above, and accordingly, further lubrication performance and lubrication life are required for the grease composition. . The demand for longer life at high temperatures is being investigated for additive formulations such as antioxidants and rust inhibitors in grease compositions based on high-viscosity synthetic hydrocarbon oils and urea compounds as thickeners. However, there is a problem that cold noise is easily generated during cold weather.

  An object of the present invention is to provide a grease composition and a grease-filled rolling bearing capable of reliably preventing the occurrence of cold abnormal noise during cold weather.

The grease composition of the present invention is a grease composition containing a base oil, a thickener and an additive, and the base oil contains at least one oil selected from ether oils, ester oils and synthetic hydrocarbon oils. The base oil has a kinematic viscosity at 40 ° C. of 15 mm ² / s to 200 mm ² / s, and the additive contains poly (meth) acrylate.
The poly (meth) acrylate is blended in an amount of 3 to 10% by weight based on the total amount of the base oil and the thickener.
The thickener is a urea compound.
The additive is obtained by adding zinc dithiophosphate to the poly (meth) acrylate.
Poly (meth) acrylate refers to polymethacrylate, polyacrylate, or a mixture of polymethacrylate and polyacrylate.

The grease-enclosed rolling bearing of the present invention is a rolling bearing comprising an inner ring and an outer ring, and a rolling element interposed between the inner ring and the outer ring, and the grease composition is enclosed around the rolling element. And
The grease-filled rolling bearing is used in an electrical accessory for automobiles that rotatably supports a rotating shaft that is driven to rotate by engine output on a stationary member, and is a heat and cold resistant noise bearing.
The automotive electrical accessory is a fan coupling device, an alternator, an idler pulley, a tension pulley, an electromagnetic clutch, or a compressor.

The grease composition of the present invention is a grease composition containing a base oil, a thickener and an additive, and the base oil contains at least one oil selected from ether oils, ester oils and synthetic hydrocarbon oils. The base oil has a kinematic viscosity at 40 ° C. of 15 mm ² / s to 200 mm ² / s, and the additive contains poly (meth) acrylate, so that a decrease in viscosity at low temperatures can be suppressed. As a result, it exhibits good lubricity in a wide temperature range from low temperature to high temperature, can prevent the occurrence of cold noise immediately after starting at low temperature, and can maintain high temperature durability for a long time It becomes a grease composition and becomes a grease composition for encapsulating a bearing that can extend the life of the bearing as much as possible.

The grease-enclosed bearing of the present invention is a bearing comprising an inner ring and an outer ring and rolling elements interposed between the inner ring and the outer ring, and the grease composition is enclosed around the rolling elements. Rolling bearings that exhibit good lubricity in a wide temperature range, can prevent cold noise immediately after starting at low temperatures, and can maintain high temperature durability for a long time. It is possible to extend the lifetime of the as much as possible.
Since the grease-enclosed rolling bearing is a rolling bearing used in an automotive electrical accessory, it is possible to reliably prevent the generation of cold noise during cold weather while maintaining lubrication performance at high temperature.

As a result of intensive studies aimed at providing a grease composition and a grease-filled rolling bearing that can surely prevent the occurrence of cold noise during cold weather, the base oil constituting the grease composition is an ether oil. comprises at least one oil selected from the ester oils and synthetic hydrocarbon oils, containing the kinematic viscosity at 40 ° C. of the base oil is ^{15 mm 2 / s~200 mm 2 /} s, poly (meth) acrylate It has been found that a rolling bearing enclosing a grease composition capable of preventing cold noise can be prevented. By blending poly (meth) acrylate with the above base oil, the increase in viscosity of the grease composition during cold weather is prevented, and the effect of preventing abnormal noise during cold is increased by suppressing the occurrence of oil film unevenness on the bearing raceway surface. It is considered a thing. The present invention is based on such knowledge.

  Specific examples of the poly (meth) acrylate that can be used in the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth). Acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, Polymer or copolymer of icosyl (meth) acrylate, docosyl (meth) acrylate, tetracosyl (meth) acrylate, octacosyl (meth) acrylate and triacontyl (meth) acrylate Body and the like. These compounds may be used alone or as a mixture of any two or more of them. Among these, poly (meth) acrylates having a weight average molecular weight of 20,000 to 1,500,000 are preferable.

The base oil that can be used in the present invention includes at least one oil selected from ether oils, ester oils and synthetic hydrocarbon oils, and has a kinematic viscosity at 40 ° C. of 15 mm ² / s to 200 mm ² / s. It is. If it is less than 15 mm ² / s, the heat resistance is low and the high temperature durability is poor. Also, if it exceeds 200 mm ² / s, the torque becomes large, so the heat generation becomes large and it becomes easy to burn.

Base oils that can be used in the present invention are ether oils, ester oils or synthetic hydrocarbon oils. Moreover, you may mix these arbitrarily.
Specifically, as the ether oil, dialkyl phenyl ether oil, alkyl triphenyl ether oil, alkyl tetraphenyl ether oil, etc.
Examples of ester oils include diester oils, polyol ester oils, complex ester oils thereof, and aromatic ester oils.
Moreover, PAO oil etc. can be mentioned as a synthetic hydrocarbon oil.
Among these, considering the lubrication performance at high temperature and high speed and the lubrication life, it is preferable to contain synthetic hydrocarbon (PAO) oil, alkyldiphenyl ether oil, and ester oil synthetic lubricant.
In order not to lower the lubrication performance and lubrication life at high temperature and high speed, the kinematic viscosity of the base oil at 40 ° C. is preferably 15 mm ² / s to 200 mm ² / s. In the present invention, it is preferable to mix any two oils.

  The PAO oil is usually an α-olefin or an isomerized α-olefin oligomer or polymer mixture. Specific examples of the α-olefin include 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1 -Nonadecene, 1-eicocene, 1-docosene, 1-tetracocene and the like can be mentioned, and usually a mixture thereof is used.

Ｒ₁ 、Ｒ₃ は、炭素数 6〜12 の芳香族系炭化水素基、炭素数 6〜20 の脂肪族系炭化水素基、炭素数 6〜20 の脂環族系炭化水素基を表わし、Ｒ₁ 、Ｒ₃ は同一であっても異なっていてもよい。Ｒ₂ は、炭素数 6〜12 の芳香族系炭化水素基を表わす。
なお、ウレア化合物の製造方法の一例としては、ジイソシアネート化合物にイソシアネート基当量のアミン化合物を反応させて得られる。また、ジウレア以外にポリウレア等も使用できる。 The urea compound that can be used in the present invention is preferably a diurea having two urea bonds in the molecule, and is represented by the following chemical formula 1.

R ₁ and R ₃ represent an aromatic hydrocarbon group having 6 to 12 carbon atoms, an aliphatic hydrocarbon group having 6 to 20 carbon atoms, and an alicyclic hydrocarbon group having 6 to 20 carbon atoms; ₁ and R ₃ may be the same or different. R ₂ represents an aromatic hydrocarbon group having 6 to 12 carbon atoms.
In addition, as an example of the manufacturing method of a urea compound, it is obtained by making the amine compound of an isocyanate group equivalent react with a diisocyanate compound. In addition to diurea, polyurea and the like can also be used.

  The blending degree of the grease composition that can be used in the present invention is preferably in the range of 150 to 400. If it is less than 150, the lubrication performance at low temperatures deteriorates, and if it exceeds 400, the grease composition tends to leak, which is not preferable.

The grease composition of the present invention comprises the above base oil and thickener as essential components, and further contains poly (meth) acrylate, and further includes an extreme pressure agent, an antioxidant, a rust inhibitor, and a metal deactivator. Conventional additives for grease such as an agent and an oily agent can be further blended.
Extreme pressure agent:
By blending an extreme pressure agent, load resistance and extreme pressure properties can be improved. For example, the following compounds can be used. As organometallic compounds, organic molybdenum compounds such as molybdenum dithiocarbamate and molybdenum dithiophosphate, organic zinc compounds such as zinc dithiocarbamate, zinc dithiophosphate and zinc phenate, organic antimony compounds such as antimony dithiocarbamate and antimony dithiophosphate, Organic selenium compounds such as selenium dithiocarbamate, organic bismuth compounds such as bismuth naphthenate and bismuth dithiocarbamate, organic iron compounds such as iron dithiocarbamate and iron octylate, organic copper compounds such as copper dithiocarbamate and copper naphthenate, naphthenic acid Organic lead compounds such as lead and lead dithiocarbamate, organic tin compounds such as tin maleate and dibutyltin sulfide, or organic sulfonates, phenates and phosphates of alkali metals and alkaline earth metals Sulfonates, gold, silver, titanium, an organometallic compound such as cadmium can also 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, polytetrafluoroethylene, 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. In addition, when poly (meth) acrylate is added to the grease composition, it is particularly preferable to use zinc dithiophosphate.

Antioxidant:
As the antioxidant, an antioxidant, an ozone deterioration inhibitor, and an antioxidant that are added to rubber, plastic, lubricating oil, and the like can be appropriately selected and used. For example, the following compounds can be used. That is, phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine, p, p'-dioctyldiphenylamine An amine compound such as N, N′-diisopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, or the like can be used.

  A phenolic antioxidant can also be used. Examples of the phenolic antioxidant include 2,6-di-t-dibutylphenol, n-octadecyl-3- (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate, tetrakis- ( Methylene-3- (3 ′, 5′-di-t-butyl-4-hydroxyphenyl) propionate) methane, 2,2′-methylenebis- (4-methyl-6-tert-butylphenol), 4,4′- Butylidenebis- (3-methyl-6-tert-butylphenol) and the like.

anti-rust:
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, organic carboxylates, phenates, phosphonates, alkyls such as alkyl or alkenyl succinates, alkenyls Succinic acid derivatives, partial esters of polyhydric alcohols such as sorbitan 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, Higher alcohols such as isostearyl alcohol, esters of higher alcohols and higher fatty acids, thiazoles such as 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptothiadiazole, 2- (decyldithio) -be Imidazole compounds such as diimidazole and benzimidazole, disulfide compounds such as 2,5-bis (dodecyldithio) -benzimidazole, phosphate esters such as trisnonylphenyl phosphite, dilaurylthiopropio Thiocarboxylic acid ester compounds such as nates can be used. Corrosion inhibitors such as nitrites, nitrates, chromates, phosphates, molybdates, tungstates that passivate the metal surface can also be used.
Metal deactivator:
As the metal deactivator, for example, a triazole compound such as benzotriazole or tolyltriazole can be used.

Oiliness agent:
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 oleyl 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.

In the grease composition of the present invention, the blending ratio of the additive is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. If the blending ratio of the additive is less than 0.1 parts by weight, the effect of adding the additive is poor, and if it exceeds 20 parts by weight, the grease is softened and leaks easily.
The blending ratio of the base oil is preferably 50 to 95 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. If the blending ratio of the base oil is less than 50 parts by weight, the grease is hard and the lubricity at low temperatures is poor. If it exceeds 95 parts by weight, it will be soft and leaky.
The blending ratio of the thickener is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. If it is less than 5 parts by weight, it becomes a liquid with a low viscosity and easily leaks, making it difficult to seal the bearing. Also, if it exceeds 50 parts by weight, it will solidify to a consistency of 100 or less, making it impractical as a grease for enclosing a bearing.

An example of a grease-filled rolling bearing according to the present invention is shown in FIG. FIG. 1 is a cross-sectional view of a deep groove ball bearing.
In the grease-filled rolling bearing 1, an inner ring 2 having an inner ring rolling surface 2a on the outer peripheral surface and an outer ring 3 having an outer ring rolling surface 3a on the inner peripheral surface are arranged concentrically, and the inner ring rolling surface 2a and the outer ring rolling surface are arranged. Several rolling elements 4 are arrange | positioned between 3a. Sealers 6 that are fixed to the cage 5, the outer ring 3, and the like that hold the plurality of rolling elements 4 are provided in the axially opposite end openings 8a, 8b of the inner ring 2 and the outer ring 3, respectively. A grease composition 7 is enclosed at least around the rolling element 4.

An example of an automobile electrical equipment / auxiliary machine is shown in FIG. FIG. 2 is a sectional view of the fan coupling device. The fan coupling device includes an oil chamber 11 in which a viscous fluid such as silicone oil is filled in a case 10 that supports a cooling fan 9 and a stirring chamber 12 in which a drive disk 18 is incorporated. A port 14 is formed in the partition plate 13 provided therebetween, and an end of a spring 15 that opens and closes the port 14 is fixed to the partition plate 13.
A bimetal 16 is attached to the front surface of the case 10, and a piston 17 of a spring 15 is provided on the bimetal 16. The bimetal 16 becomes flat when the temperature of the air that has passed through the radiator is lower than a set temperature, for example, 60 ° C., the piston 17 presses the spring 15, and the spring 15 closes the port 14. When the temperature of the air exceeds the set temperature, the bimetal 16 bends outward as shown in FIG. 3B, the piston 17 releases the pressure of the spring 15, and the spring 15 is elastically deformed. Port 14 is opened.
When the temperature of the air that has passed through the radiator is lower than the set temperature of the bimetal 16 in the operating state of the fan coupling device having the above configuration, the port 14 is closed by the spring 15, so that the viscous fluid in the oil chamber 3 is Does not flow into the stirring chamber 12, and the viscous fluid in the stirring chamber 12 is sent into the oil chamber 11 from the circulation hole 19 provided in the partition plate 5 by the rotation of the drive disk 18.
For this reason, the amount of viscous fluid in the stirring chamber 12 becomes small, and the shear resistance due to the rotation of the drive disk 18 becomes small. Therefore, the transmission torque to the case 10 decreases, and the fan 9 rotates at a low speed.
When the temperature of the air that has passed through the radiator exceeds the set temperature of the bimetal 16, the bimetal 16 is bent outward as shown in FIG. 3B, and the piston 17 releases the pressure of the spring 15. At this time, since the spring 15 is elastically deformed in a direction away from the partition plate 13, the port 14 is opened, and the viscous fluid in the oil chamber 11 flows from the port 14 into the stirring chamber 12.
For this reason, the shear resistance of the viscous fluid due to the rotation of the drive disk 18 increases, the rotational torque to the case 10 increases, and the fan 9 supported by the rolling bearing rotates at high speed.
In the fan coupling device, the rotation speed of the fan 9 changes according to the temperature change, so that the warm-up can be accelerated and the cooling water can be prevented from being overcooled, thereby effectively cooling the engine. When the engine temperature is low, the fan 9 is equivalent to being disconnected from the drive shaft 20, and when the engine temperature is high, it is equivalent to being connected. Thus, the rolling bearing 1 is used in a wide temperature range and a wide rotation range from a low temperature to a high temperature.

An example of an alternator for automobile electrical equipment and auxiliary equipment is shown in FIG. FIG. 3 is a sectional view of the alternator. The alternator includes a pair of frames 21 a and 21 b that form a stationary member housing, and a rotor rotating shaft 23 having a rotor 22 mounted thereon is rotatably supported by a pair of ball bearings 1. A rotor coil 24 is attached to the rotor 22, and a three-turn stator coil 26 is attached to a stator 25 disposed on the outer periphery of the rotor 22 with a phase of 120 °.
The rotor rotating shaft 23 is rotationally driven with a rotational torque transmitted by a belt (not shown) to a pulley 27 attached to the tip thereof. Since the pulley 27 is attached to the rotor rotating shaft 23 in a cantilever state and vibration is also generated as the rotor rotating shaft 23 rotates at high speed, the ball bearing 1 that supports the pulley 27 side in particular receives a severe load. .

An example of an idler pulley used as a belt tensioner for an automobile accessory drive belt is shown in FIG. FIG. 4 is a sectional view of the idler pulley.
The pulley includes a pulley body 28 made of a steel plate press and a single row deep groove ball bearing 1 fitted to the inner diameter of the pulley body 28. The pulley main body 28 includes an inner diameter cylindrical portion 28a, a flange portion 28b extending from one end of the inner diameter cylindrical portion 28a to the outer diameter side, an outer diameter cylindrical portion 28c extending in the axial direction from the flange portion 28b, and the other end of the inner diameter cylindrical portion 28a. This is an annulus composed of a flange portion 28d extending to the inner diameter side. The outer ring 3 of the ball bearing 1 is fitted to the inner diameter of the inner cylindrical portion 28a, and a pulley peripheral surface 28e that contacts the belt driven by the engine is provided on the outer diameter of the outer cylindrical portion 28c. By bringing the pulley peripheral surface 28e into contact with the belt, the pulley functions as an idler.
The ball bearing 1 includes an outer ring 3 fitted to the inner diameter of the inner cylindrical portion 28a of the pulley body 28, an inner ring 2 fitted to a fixed shaft (not shown), and the transfer surfaces 2a, 3a of the inner / outer rings 2, 3. A plurality of incorporated rolling elements 4, a cage 5 that holds the rolling elements 4 at equal intervals around the circumference, and a pair of seal members 6 that seal grease are formed. The inner ring 2 and the outer ring 3 are integrally formed. .

An electromagnetic clutch and a compressor using the rolling bearing for an automotive electrical accessory according to the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of the electromagnetic clutch and the scroll compressor.
The operation of the electromagnetic clutch 29 will be described below. The rolling bearing 1 incorporated in the pulley 31 is attached to the nose portion 37 of the compressor 30 and its outer ring is always rotated by belt driving. When the coil 34 a of the stator 34 is energized, the clutch plate 36 fixed to the compressor rotating shaft 35 is attracted to the pulley 31 by the magnetic flux generated by the coil current and connected to drive the compressor rotating shaft 35.
The electromagnetic clutch has functions such as transmission and interruption of torque between the engine and the compressor by the above operation, procurement of the compressor rotation speed by selection of the pulley diameter, shock reduction during compressor operation, and absorption of torque fluctuation during steady rotation.
The scroll-type compressor 30 includes a movable scroll 32 and a fixed scroll 33 that are a pair of spiral parts, and a structure in which a space formed between both scrolls is reduced in volume while moving from the outside to the center to compress the refrigerant. It has become.
The rotation speed of the compressor rotating shaft 35 is 10000 rpm or more, the maximum is about 12000 rpm, and the ambient temperature may rise to about 180 ° C. Therefore, the rolling bearing 1 of the electromagnetic clutch 29 and other rolling bearings (not shown) in the compressor shown in FIG. 5 need to have sufficient durability even under the use conditions.

Examples 1 to 6
Base oils, thickeners and additives were blended in the proportions shown in Table 1 for each example to obtain grease compositions. For the additive, the blending amount with respect to 100 parts by weight of the total of the thickener and the base oil was expressed in parts by weight. The obtained grease composition was subjected to cold noise measurement and high temperature grease life test, and the results are also shown in Table 1. Test methods and test conditions are as follows.

Comparative Examples 1 to 3
For each comparative example, a base oil and a thickener were blended in the proportions shown in Table 1 to obtain a grease composition. The obtained grease composition was subjected to cold abnormal noise measurement and high temperature grease life test in the same manner as in the Examples, and the results are also shown in Table 1. Test methods and test conditions are as follows.

Cold noise measurement:
0.9 g of the grease composition obtained in each of the examples and comparative examples is sealed in a rolling bearing (6203) having a radial clearance of 0 to 8 μm when incorporated in a test pulley, and is kept in a low temperature bath at −60 ° C. for a certain period of time. After being put in, it is taken out and attached to a bearing rotating device installed at room temperature. When the bearing temperature reaches −20 ° C., it is rotated at a rotational speed of 2700 rpm under a radial load of 127 N. The presence or absence of occurrence was confirmed by hearing. When the ratio of the number of cold noise generations to the total number of tests (n = 10) was less than 30%, it was evaluated that the cold noise resistance was excellent.

High temperature grease life test:
The grease composition obtained in each example and each comparative example (1.8 g) was sealed in a rolling bearing (6204), under an axial load of 670 N and a radial load of 67 N, at a bearing temperature of 150 ° C. and a rotational speed of 10,000 rpm. The time until rotating and baking was measured. When the time until baking was 500 hours or more, it was evaluated as having excellent heat resistance.

  As shown in Table 1, the grease using poly (meth) acrylate is unlikely to generate abnormal noise when cold and has a high temperature and long life. This is considered to be due to the increase in the viscosity of the grease composition during cold and the occurrence of oil film unevenness on the bearing raceway surface by the blending of the above base oil, thereby increasing the effect of preventing abnormal noise during cold. . Therefore, it can be suitably used for a rolling bearing used in cold weather, especially a rolling bearing for electrical equipment.

  The grease composition of the present invention exhibits good lubricity in a wide temperature range from low temperature to high temperature, and can prevent the occurrence of cold abnormal noise immediately after starting at low temperature, so the grease composition of the present invention is enclosed. Such a bearing can be suitably used for a bearing for a vehicle such as an automobile during cold weather.

It is sectional drawing of a rolling bearing. It is sectional drawing of a fan coupling apparatus. It is sectional drawing of an alternator. It is sectional drawing of an idler pulley. It is sectional drawing of an electromagnetic clutch and a compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Deep groove ball bearing 2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Seal member 7 Grease composition

Claims (5)

A rolling bearing comprising an inner ring and an outer ring, and a rolling element interposed between the inner ring and the outer ring, wherein a grease composition is sealed around the rolling element,
The rolling bearing is used in an automotive electrical accessory that rotatably supports a rotating shaft that is driven to rotate by engine output on a stationary member, and is a heat and cold resistant noise bearing.
The grease composition includes a base oil, a thickener, and an additive, wherein the base oil includes at least one oil selected from ether oil, ester oil, and synthetic hydrocarbon oil, A grease-enclosed rolling bearing, wherein the base oil has a kinematic viscosity at 40 ° C. of 15 mm ² / s to 200 mm ² / s, and the additive contains poly (meth) acrylate.   The grease-filled rolling bearing according to claim 1, wherein 3 to 10% by weight of the poly (meth) acrylate is blended with respect to the total amount of the base oil and the thickener.   The grease-enclosed rolling bearing according to claim 1, wherein the thickener is a urea compound.   The grease-enclosed rolling bearing according to claim 1, wherein the additive is obtained by adding zinc dithiophosphate to the poly (meth) acrylate. The grease-filled rolling bearing according to any one of claims 1 to 4, wherein the automotive electrical accessory is a fan coupling device, an alternator, an idler pulley, a tension pulley, an electromagnetic clutch, or a compressor. .

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