JP2007255493A - Roll bearing for automobile equipment/accessories - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roll bearing for an automobile equipment/accessories capable of effectively preventing detachment on a rolling surface owing to hydrogen brittleness. <P>SOLUTION: A rotary shaft driven by the engine output is supported freely rotatably by a static member and the roll bearing 1 comprises an inner ring 2 and an outer ring 3, a plurality of roll elements 4 standing between the inner ring 2 and the outer ring 3, an axial direction both ends opening part 8a of the inner ring 2 and the outer ring 3 for sealing a grease composition 7 around the roll elements 4 and a sealing member 6 provided in the 8b. The grease composition 7 is completed by blending additives to the base grease which is made of a base oil and a thickener. The additive includes aluminum series additives and the blending ratio of the aluminum series additive is 0.05 to 10 pts.wt. against the base grease 100 pts.wt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a rolling bearing for automobile electrical equipment / auxiliary machinery, and more particularly, to a motor electrical component such as a fan coupling device, an alternator, an idler pulley, an electromagnetic clutch for a car air conditioner, an electric fan motor, and a rolling bearing for auxiliary machinery.

In recent years, along with demands for miniaturization, weight reduction and quietness improvement of automobiles, miniaturization, weight reduction and sealing of engine compartments have been attempted for the electrical parts and auxiliary parts. The demand for high output and high efficiency is increasing in the performance of the engine itself, and in the electrical equipment and auxiliary equipment in the engine room, a method of compensating for the decrease in output caused by downsizing by rotating at high speed is adopted. Yes.
Hereinafter, outlines of a rolling bearing for a fan coupling device, a rolling bearing for an alternator for an automobile, and a rolling bearing for an idler pulley will be described as examples of the rolling bearing for an electric vehicle / auxiliary machine.

A fan coupling device for automobiles has a housing in which viscous fluid is sealed inside and a fan for blowing air on the outer peripheral surface is connected to a rotor directly connected to the engine via a bearing, and increases or decreases in response to the ambient temperature. It is a device that performs optimum ventilation corresponding to the engine temperature by controlling the amount of drive torque transmitted from the engine and the rotational speed of the fan using the shearing resistance of the viscous fluid.
For this reason, the rolling bearings for fan coupling devices have a rotational speed of 10000 10000 at high temperatures of 150 ° C or higher during high-speed operation in summer, in addition to uneven rotation where the rotational speed varies from 1000 rpm to 10000 rpm as the engine temperature varies. Heat resistance, grease sealability, and durability that are able to withstand extremely harsh environments such as high-speed rotation above rpm are required.

  The alternator for automobiles has a function of generating electric power by receiving rotation of an engine with a belt, supplying electric power to an electric load of the vehicle, and charging a battery. For this reason, rolling bearings for alternators are required to have heat resistance, grease sealability, and durability that can withstand extremely harsh environments such as high-speed rotations of 10,000 rpm or higher at high temperatures of 150 ° C or higher.

The idler pulley for automobiles is used as a belt tensioner for a drive belt that transmits engine rotation to the auxiliary equipment of the automobile, and is used to apply tension as a tensioner to the belt when the center distance is fixed. It functions in combination with a pulley function and an idler function that reduces the engine compartment volume by changing the running direction of the belt or avoiding obstacles.
For this reason, idler pulley rolling bearings are required to have heat resistance, grease sealability, and durability that can withstand extremely harsh environments such as high-speed rotation of 10,000 rpm or higher at a high temperature of 150 ° C or higher.

As a grease composition suitable for rolling bearings used at high temperatures and high speeds such as rolling bearings for automobile electrical equipment and auxiliary machinery, an amide wax having a melting point of 80 ° C. or higher that has an antioxidant ability for base oil is used as a grease. 0.5% to 10% by weight of the composition is mixed with a base oil having a kinematic viscosity of 20 mm to 150 mm ² / sec at 40 ° C., and the thickener of the grease composition is a urea-based thickener. A grease composition containing 5 wt% to 30 wt% of the entire grease composition is known (see Patent Document 1).
However, due to severe usage conditions, specific peeling accompanied with white structure change occurs early on the rolling surface of the rolling bearing, which is a problem. This specific exfoliation is different from the exfoliation from the inside of the rolling contact surface caused by normal metal fatigue, and is a fracture phenomenon that occurs from a relatively shallow portion of the surface of the rolling contact surface and is considered to be hydrogen embrittlement caused by hydrogen.

As a method for preventing such an unusual peeling phenomenon accompanied by a white texture change that occurs at an early stage, for example, a method of adding a passivating agent to a grease composition (see Patent Document 2), or a method of adding bismuth dithiocarbamate (See Patent Document 3).
However, due to the severe use conditions of rolling bearings used in automobile electrical equipment and accessories in recent years, sufficient measures cannot be taken with the method of adding a passivating agent or the method of adding bismuth dithiocarbamate.
JP 2003-105366 A JP-A-3-210394 JP-A-2005-42102

  The present invention has been made to cope with such a problem, and an automobile capable of effectively preventing separation on a rolling surface due to hydrogen embrittlement under the use conditions of a rolling bearing used in automobile electrical equipment and auxiliary equipment. The purpose is to provide rolling bearings for electrical equipment and auxiliary equipment.

  An automotive electrical equipment / auxiliary rolling bearing according to the present invention is an automotive electrical equipment / auxiliary rolling bearing that rotatably supports a rotating shaft driven by engine output on a stationary member, the rolling bearing comprising an inner ring and An outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a seal member provided at both axial openings of the inner ring and the outer ring for sealing the grease composition around the rolling element. The grease composition is a grease composition obtained by adding an additive to a base grease comprising a base oil and a thickener, and the additive is at least one selected from aluminum powder and an aluminum compound. One aluminum-based additive is contained, and the mixing ratio of the aluminum-based additive is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease. That.

The aluminum compound is at least one compound selected from aluminum carbonate and aluminum nitrate.
The thickener is a urea-based thickener.
The base oil is at least one oil selected from alkyl diphenyl ether oil and poly-α-olefin oil.

  The grease composition to be enclosed in rolling bearings for automobile electrical equipment and auxiliary equipment is formed by blending at least one aluminum-based additive selected from aluminum powder and aluminum compound with base grease consisting of base oil and thickener. Thus, the occurrence of peculiar delamination due to hydrogen embrittlement seen in bearings used in automobiles and industrial machines can be suppressed, and the life of rolling bearings for automobile electrical equipment and auxiliary equipment can be extended.

FIG. 1 shows an example of a rolling bearing for automobile electrical equipment and auxiliary equipment that rotatably supports a rotating shaft that is driven to rotate by engine output on a stationary member. FIG. 1 is a cross-sectional view of a deep groove ball bearing in which a grease composition is enclosed.
In the deep groove ball 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 3a. A plurality of rolling elements 4 are arranged between the two. 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 cross-sectional view of the structure 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 below a set temperature, for example, 60 ° C., the piston 17 presses the spring 15, and the spring 15 closes the port 14. When the air temperature exceeds the set temperature, the bimetal 16 is bent outward as shown in FIG. 2B, 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 as shown in FIG. Therefore, the viscous fluid in the oil chamber 11 does not flow into the stirring chamber 12, and the viscous fluid in the stirring chamber 12 enters the oil chamber 11 from the circulation hole 19 provided in the partition plate 13 by the rotation of the drive disk 18. Sent. 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. 2B, 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.
As described above, since the fan coupling device changes the rotational speed of the fan 9 in accordance with the temperature change, the warming-up can be accelerated, the cooling water can be prevented from being overcooled, and the engine can be cooled effectively. . The fan 9 is equivalent to being disconnected from the drive shaft 20 when the engine temperature is low, and is equivalent to being connected to the drive shaft 20 when the engine temperature is high. 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 structure of the alternator. In the alternator, a rotor rotating shaft 23 having a rotor 22 mounted on a pair of frames 21 a and 21 b forming a housing which is a stationary member is rotatably supported by a pair of ball bearings 1 and 1. A rotor coil 24 is attached to the rotor 22, and a three-winding stator coil 26 is attached to the stator 25 disposed on the outer periphery of the rotor 22 at 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. .

FIG. 4 shows an example of an idler pulley used as a belt tensioner for an accessory driving belt of an automobile. FIG. 4 is a sectional view of the structure 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 an inner diameter cylindrical portion 28a. This is an annulus composed of a flange portion 28d extending from the other end 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 this pulley peripheral surface 28e into contact with the belt, the pulley serves as an idler.

  The ball bearing 1 includes an outer ring 3 fitted to the inner diameter of the inner cylindrical portion 28 a of the pulley body 28, an inner ring 2 fitted to a fixed shaft (not shown), and transfer surfaces 2 a and 3 a of the inner and outer rings 2 and 3. A plurality of rolling elements 4 incorporated between them, a cage 5 that holds the rolling elements 4 at equal intervals around the circumference, and a pair of seal members 6 that seal the grease composition. Each is integrally formed.

By adding at least one aluminum-based additive selected from aluminum powder and an aluminum compound to the grease composition used for the above-mentioned automotive electrical equipment / auxiliaries, the aluminum powder is formed on the friction wear surface or the newly formed metal surface exposed by wear. Adhesion or an aluminum compound reacts, and an aluminum film is formed on the bearing rolling surface together with iron oxide.
The iron oxide and aluminum film formed on the rolling surface of the bearing can suppress generation of hydrogen due to decomposition of the grease composition, and can prevent unique peeling due to hydrogen embrittlement.

Aluminum additives to be added to the grease composition used in the rolling bearings for automobile electrical equipment and auxiliary equipment of the present invention include aluminum powder, aluminum carbonate, aluminum sulfide, aluminum chloride, aluminum nitrate and hydrates thereof, aluminum sulfate, and fluoride. Aluminum bromide, aluminum bromide, aluminum iodide, aluminum oxide and its hydrate, aluminum hydroxide, aluminum selenide, aluminum telluride, aluminum phosphate, aluminum phosphide, lithium aluminate, magnesium aluminate, aluminum selenate , Aluminum titanate, aluminum zirconate, aluminum benzoate, aluminum citrate and the like. These aluminum-based additives may be added to the base grease by mixing one type or two types.
Particularly preferable in the present invention is an aluminum powder having a high extreme pressure effect because it is excellent in heat resistance and hardly decomposes thermally.

The compounding ratio of the aluminum-based additive is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease. That is, (1) When the aluminum-based additive is only aluminum powder, 0.05 to 10 parts by weight of aluminum powder with respect to 100 parts by weight of the base grease, and (2) When the aluminum-based additive is only aluminum compound , 0.05 parts by weight to 10 parts by weight of the aluminum compound with respect to 100 parts by weight of the base grease. (3) When the aluminum additive is aluminum powder and an aluminum compound, Combine 0.05 parts by weight to 10 parts by weight with the aluminum compound.
If the blending ratio of the aluminum additive is less than this blending range, peeling on the rolling surface due to hydrogen embrittlement cannot be effectively prevented. Moreover, even if it exceeds the said range, the peeling prevention effect does not improve any more.

Base oils that can be used in the present invention include mineral oils such as spindle oil, refrigerating machine oil, turbine oil, machine oil, dynamo oil, highly refined mineral oil, liquid paraffin, GTL oil synthesized by the Fischer-Tropsch process, polybutene, poly- Hydrocarbon synthetic oil such as α-olefin oil, alkylnaphthalene, alicyclic compound, or natural oil, polyol ester oil, phosphate ester oil, polymer ester oil, aromatic ester oil, carbonate ester oil, diester oil, Non-hydrocarbon synthetic oils such as polyglycol oil, silicone oil, polyphenyl ether oil, alkyldiphenyl ether oil, alkylbenzene oil, and fluorinated oil can be used.
Among these, it is preferable to use alkyl diphenyl ether oil and poly-α-olefin oil which are excellent in heat resistance and lubricity.

  Thickeners that can be used in the present invention include benton, silica gel, fluorine compounds, lithium soap, lithium complex soap, strong lucium soap, calcium complex soap, aluminum soap, aluminum complex soap, and other soaps, diurea compounds, polyurea compounds, etc. These urea compounds are mentioned. In consideration of heat resistance, cost, and the like, a urea compound is desirable.

  The urea compound is obtained by reacting an isocyanate compound with an amine compound. In order not to leave a reactive free radical, the isocyanate group of the isocyanate compound and the amino group of the amine compound are preferably blended so as to be approximately equivalent.

A diurea compound is obtained by reaction of a diisocyanate and a monoamine, for example. Examples of the diisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, etc., and monoamines include octylamine, dodecylamine, hexadecylamine, stearylamine, Examples include oleylamine, aniline, p-toluidine, cyclohexylamine and the like.
The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those similar to those used for the production of the diurea compound. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, And diaminodiphenylmethane.

By adding a thickener such as a urea compound to the base oil, a base grease for blending the aluminum additive and the like can be obtained. A base grease using a urea compound as a thickener is prepared by reacting an isocyanate compound and an amine compound in a base oil.
The blending ratio of the thickener in 100 parts by weight of the base grease is 1 part by weight to 40 parts by weight, preferably 3 parts by weight to 25 parts by weight. If the content of the thickener is less than 1 part by weight, the thickening effect will be reduced, making it difficult to make grease, and if it exceeds 40 parts by weight, the resulting base grease will be too hard and the desired effect will not be obtained. Become.

  In addition to the aluminum-based additive, a known grease additive may be included as necessary. Examples of the additives include antioxidants such as organic zinc compounds, amines, and phenolic compounds, metal deactivators such as benzotriazole, viscosity index improvers such as polymethacrylate and polystyrene, molybdenum disulfide, and graphite. Examples thereof include solid lubricants, metal sulfonates, antirust agents such as polyhydric alcohol esters, friction reducing agents such as organic molybdenum, oily agents such as esters and alcohols, and antiwear agents such as phosphorus compounds. These can be added alone or in combination of two or more.

Examples 1 to 8
In half of the base oil shown in Table 1, 4,4-diphenylmethane diisocyanate (Millionate MT manufactured by Nippon Polyurethane Industry Co., Ltd., hereinafter referred to as MDI) is dissolved in the ratio shown in Table 1, and the remaining half of the base oil is dissolved. A monoamine having a double equivalent of MDI was dissolved in the solution. The respective blending ratios and types are shown in Table 1.
A solution in which monoamine was dissolved was added while stirring the solution in which MDI was dissolved, and then the reaction was continued for 30 minutes at 100 ° C. to 120 ° C. to produce a diurea compound in the base oil.
To this, an aluminum-based additive and an antioxidant were added in the proportions shown in Table 1, and the mixture was further stirred at 100 to 120 ° C. for 10 minutes. Thereafter, the mixture was cooled and homogenized with three rolls to obtain a grease composition.

In Table 1, the synthetic hydrocarbon oil used as the base oil is Shinflud 601 manufactured by Nippon Steel Chemical Co., Ltd. with a kinematic viscosity of 30 mm ² / sec at 40 ° C, and the alkyldiphenyl ether oil is Matsumura with a kinematic viscosity of 97 mm ² / sec at 40 ° C. Moresco High Lube LB100 manufactured by Petroleum Corporation was used. Moreover, alkylated diphenylamine was used as the antioxidant.

  A rapid acceleration / deceleration test was performed on the test bearing in which the obtained grease composition was sealed. Test methods and test conditions are shown below. The results are shown in Table 1.

<Rapid acceleration / deceleration test>
The grease composition was enclosed in a rolling bearing that supports a rotating shaft that supports a pulley around which a rotating belt of an alternator, which is an example of an electrical accessory, is wound, and used as a test bearing. A rapid acceleration / deceleration test was performed on this test bearing. The rapid acceleration / deceleration test conditions are such that the operating load is set to 1960 N for the test bearing attached to the end of the rotating shaft, the rotation speed is 0 rpm to 18000 rpm, and a current of 0.1 A flows in the test bearing. The test was conducted at Then, abnormal peeling occurred in the test bearing, and the time when the vibration of the vibration detector exceeded the set value and the generator stopped (peeling life time, h) was measured. The test was terminated after 500 hours.

Comparative Examples 1 to 3
In accordance with the method according to Example 1, the base grease was prepared by selecting the thickener and the base oil at the blending ratio shown in Table 1, and the additive was further blended to obtain a grease composition. The test bearing encapsulating the obtained grease composition was evaluated by conducting the same test as in Example 1. The results are shown in Table 1.

  As shown in Table 1, in each example, all the rapid acceleration / deceleration tests showed excellent results of 400 hours or more (peeling life time). This is considered to be because the specific exfoliation accompanied by the white texture change that occurs on the rolling surface can be effectively prevented by adding the aluminum-based additive at a predetermined ratio.

  In the rolling bearing for automotive electrical equipment and auxiliary equipment according to the present invention, the aluminum-based additive in the enclosed grease composition effectively prevents specific delamination accompanied by a white structure change occurring on the rolling surface of the rolling bearing. Therefore, it shows excellent bearing life. For this reason, it can be suitably used for automobile electric parts such as car clutch air-conditioning electromagnetic clutches and electric fan motors, rolling bearings such as auxiliary machines, and motor bearings.

It is sectional drawing of a deep groove ball bearing. It is sectional drawing of the structure of a fan coupling apparatus. It is sectional drawing of the structure of an alternator. It is sectional drawing of the structure of an idler pulley.

Explanation of symbols

1 Grease-filled bearing (rolling bearing)
2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Seal member 7 Grease composition 8a, 8b Opening 9 Cooling fan 10 Case 11 Oil chamber 12 Stirring chamber 13 Partition plate 14 Port 15 Spring 16 Bimetal 17 Piston 18 Drive disk 19 Distribution Hole 20 Drive shaft 21a, 21b Frame 22 Rotor 23 Rotor rotation shaft 24 Rotor coil 25 Stator 26 Stator coil 27 Pulley 28 Pulley body

Claims (4)

A rolling bearing for automobile electrical equipment and auxiliary equipment that rotatably supports a rotating shaft that is driven to rotate by engine output on a stationary member,
The rolling bearing is provided at both ends of the inner ring and the outer ring in the axial direction in order to seal a grease composition around the inner ring and the outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and the periphery of the rolling element. And a sealed member,
The grease composition is a grease composition in which an additive is blended with a base grease comprising a base oil and a thickener, and the additive is at least one aluminum system selected from aluminum powder and an aluminum compound A rolling bearing for automobile electrical equipment / auxiliary machinery, which contains an additive, and the mixing ratio of the aluminum-based additive is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease.   2. The rolling bearing for automobile electrical equipment / auxiliary machinery according to claim 1, wherein the aluminum compound is at least one compound selected from aluminum carbonate and aluminum nitrate.   3. The rolling bearing for automobile electrical equipment / auxiliary equipment according to claim 1, wherein the thickener is a urea thickener.   4. The rolling for automobile electrical equipment / auxiliary machinery according to claim 1, wherein the base oil is at least one oil selected from alkyl diphenyl ether oil and poly-α-olefin oil. 5. bearing.

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