JP2009209991A - Grease filled bearing for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease filled bearing for a motor capable of being used for a long time even under the environment in which faster operating speed is required at a relatively low temperature, having excellent feeding performance of oil into a rolling surface. <P>SOLUTION: The grease filled bearing 1 for the motor, which is used for the motor of industrial machinery or information equipment, comprises inner ring 2 and outer ring 3, a plurality of rolling elements 4, and a seal member 6 installed in axial both-end openings 8a, 8b of the inner ring 2 and the outer ring 3. A grease composition 7 is one comprising a base oil and a urea thickener, in which the base oil has a kinetic viscosity of 15 to 30 mm<SP>2</SP>/sec at 40°C, and in which the urea thickener is obtained by reaction between a polyisocyanate component and a monoamine component, the monoamine component containing 50 mol% or more of at least one monoamine selected from among aliphatic monoamines and alicyclic monoamines based on all the monoamines, and is contained in an amount of 3 wt.% to less than 9 wt.% on the total amount of the grease. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a grease-filled bearing for motors, and more particularly, to a grease-filled bearing for motors for industrial machines and information devices such as motors for ventilation fans, blower motors for fuel cells, cleaner motors, fan motors and stepping motors.

  In recent years, in general-purpose motors such as AC motors and DC motors, miniaturization of motors has progressed, and bearings tend to be operated at higher speeds and higher surface pressures. Sufficient durability cannot be obtained by using a metal soap grease such as lithium soap such as Multemp SRL (manufactured by Kyodo Yushi Co., Ltd.). For this reason, urea grease having higher durability tends to be used. For example, a urea grease is known in which a carbonate compound having a predetermined structure used for a base oil and a urea compound used for a thickener are defined in a predetermined amount (see Patent Document 1). This is intended to improve durability by lowering the coefficient of friction.

  In addition, the operating temperature of motors used in automotive engine-related electrical accessories is 150 ° C or higher, while ventilation fan motors, fuel cell blower motors, cleaner motors, fan motors, servo motors, stepping motors, etc. Motors for electrical equipment such as motors for industrial machinery or information equipment, automobile starter motors, electric power steering motors, steering adjustment tilt motors, wiper motors, power window motors, etc. are used at a relatively low temperature of less than 150 ° C. In many cases.

Under such a relatively low temperature use environment, the conventional urea grease shown in Patent Document 1 or the like has poor fluidity of the base oil, and when higher speed is required, supply of the base oil to the rolling surface However, there is a problem that it is difficult to catch up and is liable to cause poor lubrication.
Japanese Patent No. 3910953

  The present invention has been made to cope with such problems, and is used for a motor that is excellent in oil supply to a rolling surface and can be used for a long time even in an environment where high speed is required at a relatively low temperature. The purpose is to provide a grease-filled bearing.

The grease-filled bearing for a motor of the present invention is a grease-filled bearing for a motor that supports a rotor of the motor, and the grease-filled bearing includes an inner ring and an outer ring, and a plurality of rolling elements interposed between the inner ring and the outer ring. In addition, seal members for sealing the grease composition around the rolling elements are provided at both axial openings of the inner ring and the outer ring, and the grease composition contains a base oil and a urea-based thickener. The base oil has a kinematic viscosity at 40 ° C. of 15 to 30 mm ² / sec, and the urea-based thickener is obtained by reacting a polyisocyanate component with a monoamine component. A monoamine component containing 50 mol% or more of at least one monoamine selected from an aliphatic monoamine and an alicyclic monoamine based on the total monoamine, , Characterized in that it contains the urea thickener less than 3 wt% to 9 wt%.

The base oil has a surface tension of 25 mN / m or more and a density of 0.95 g / cm ³ or less.

  The base oil is at least one oil selected from a synthetic hydrocarbon oil, an ester oil, and an alkyl diphenyl ether oil.

  The grease-filled bearing for a motor is a deep groove ball bearing.

  The grease bearing for motors is used in a temperature environment of less than 150 ° C. In particular, it is used for motors of industrial machines or information equipment.

The grease-enclosed bearing for a motor of the present invention comprises a grease composition encapsulated in the bearing and a base oil having a kinematic viscosity of 15 to 30 mm ² / sec at 40 ° C. and 3 weights of a predetermined urea thickener. % To less than 9% by weight, so even when using a small amount of grease, it is excellent in the ability to supply oil to the raceway surface under high-speed rotation while maintaining load resistance when used at relatively low temperatures.

  For this reason, the grease-filled bearing for a motor of the present invention maintains a good lubrication state and requires a long life, such as a motor for a ventilation fan, a blower motor for a fuel cell, a cleaner motor, a fan motor, a servo motor, a stepping motor, etc. It can be suitably used for motors for electrical equipment such as motors for industrial machines or information equipment, starter motors for automobiles, electric power steering motors, tilt motors for steering adjustment, wiper motors, and power window motors.

An example of a grease-filled bearing for a motor that supports the rotor of the motor is shown in FIG. 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. A cage 5 that holds the plurality of rolling elements 4 is provided. In addition, seal members 6 fixed to the outer ring 3 and the like are provided in the axially opposite end openings 8a and 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. This grease composition 7 comprises a base oil having a kinematic viscosity of 15 to 30 mm ² / sec at 40 ° C., which will be described later, and a predetermined urea-based thickener added at 3 wt% or more and less than 9 wt%. Composition 7.

  An example of the motor is shown in FIG. FIG. 2 is a sectional view of the structure of the motor. The motor includes a stator 10 made of a magnet for a motor disposed on the inner peripheral wall of the jacket 9, a rotor 13 around which a winding 12 fixed to the rotating shaft 11 is wound, and a commutator fixed to the rotating shaft 11. 14, a brush holder 15 disposed on an end frame 17 supported by the jacket 9, and a brush 16 accommodated in the brush holder 15. The rotating shaft 11 is rotatably supported by the jacket 9 by the deep groove ball bearing 1 and a support structure for the bearing 1. The bearing 1 is a grease-filled bearing for a motor of the present invention.

The grease-filled bearing for a motor in the present invention prevents lubrication failure during high-speed rotation and can be used for a long time even when used in a relatively low temperature environment of less than 150 ° C. Here, the temperature environment of less than 150 ° C. means a condition in which the temperature of the fixed ring of the bearing in use is less than 150 ° C.
Specific applications under such a temperature environment include motors for industrial machines or information devices such as motors for ventilation fans, blower motors for fuel cells, cleaner motors, fan motors, servo motors, stepping motors, starter motors for automobiles, Examples include motors for electrical equipment such as an electric power steering motor, a steering adjustment tilt motor, a wiper motor, and a power window motor. These are usually used in a temperature environment of about 70 to 120 ° C.

  The grease-enclosed bearing for motors of the present invention preferably encloses grease of 1 volume% or more and less than 10 volume% of the volume of the bearing gap. If the amount is less than 1% by volume, the amount of grease necessary for lubrication is insufficient, and it is easy to be depleted. If the amount is 10% by volume or more, the torque due to stirring increases and heat generation increases, the lubrication life is not improved, and the cost increases. It is not preferable from an environmental point of view.

  In addition to the deep groove ball bearing shown in FIG. 1, the grease-filled bearing for the motor of the present invention includes an angular ball bearing, a cylindrical roller bearing, a tapered roller bearing, a self-aligning roller bearing, a needle roller bearing, a thrust cylindrical roller bearing, a thrust Tapered roller bearings, thrust needle roller bearings, thrust self-aligning roller bearings and the like can also be used. Among these, it is preferable to use a deep groove ball bearing having both rotational accuracy at high speed rotation, load resistance and low cost.

As the base oil that can be used in the present invention, a lubricating oil having a kinematic viscosity at 40 ° C. (hereinafter simply referred to as kinematic viscosity) of 15 to 30 mm ² / sec can be used. In particular, a lubricating oil having a kinematic viscosity of 15 to 25 mm ² / sec is preferable. When the kinematic viscosity is less than 15 mm ² / sec, the viscosity is too low to obtain sufficient load resistance. Also, if the kinematic viscosity exceeds 25 mm ² / sec, the oil supply to the raceway surface becomes insufficient with high-speed rotation, and the bearing life will be reached early.

As a kind of the lubricating oil, a synthetic hydrocarbon oil, an ester oil, an alkyl diphenyl ether oil, or a mixed oil thereof is preferable.
Further, it is preferable that the kinematic viscosities of synthetic hydrocarbon oil, ester oil, and alkyl diphenyl ether oil are 15 to 30 mm ² / sec. Even if it is a mixed oil as it is this range, the range of kinematic viscosity can be 15-30 mm < ² > / sec.
When using mixed oil, it is preferable to use a mixed oil of synthetic hydrocarbon oil and ester oil. The mixing ratio is preferably synthetic hydrocarbon oil / ester oil (weight ratio) = 8/2 to 2/8. In particular, the synthetic hydrocarbon oil is preferably equal to or more in weight than the ester oil.
Alkyl diphenyl ether oil can be used alone.

Examples of the synthetic hydrocarbon oil include poly-α-olefins such as normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, and co-oligomer of 1-decene and ethylene.
Examples of ester oils include dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl tartrate, methyl acetyl cinnolate, and the like, trioctyl trimellitate, trioctyl Aromatic ester oils such as decyl trimellitate and tetraoctyl pyromellitate, polyol ester oils such as trimethylolpropane caprylate, trimethylolpropane verargonate, pentaerythritol-2-ethylhexanoate, and pentaerythritol verargonate And carbonate ester oil.
Examples of the alkyl diphenyl ether oil include monoalkyl diphenyl ether, dialkyl diphenyl ether, and polyalkyl diphenyl ether.

The base oil that can be used in the present invention has a surface tension of 25 mN / m or more, preferably 27 to 40 mN / m, and a density of 0.95 g / cm ³ or less, preferably 0.8 to 0.93 g / cm ³ . If the surface tension is less than 25 mN / m, it will be difficult to move to the rolling section due to capillary action, and it will not be possible to stably supply the required amount of oil at high speed, and if the density exceeds 0.95 g / cm ³ Due to the phenomenon, it is difficult to move to the rolling section, and the required amount of oil cannot be stably supplied at high speed.

The urea-based thickener that can be used in the present invention is obtained by reacting a polyisocyanate component and a monoamine component.
Examples of the polyisocyanate component include phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate. Of these, aromatic diisocyanates are preferred.
Moreover, the polyisocyanate obtained by reaction with excess diisocyanate by molar ratio with respect to diamine and this diamine can be used. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, and diaminodiphenylmethane.

The monoamine component is a monoamine component containing at least one monoamine selected from an aliphatic monoamine and an alicyclic monoamine in an amount of 50 mol% or more, preferably 80 mol% or more based on the total monoamine. By containing 50 mol% or more, it is not easily broken by the shearing force of the thickener under high speed, and the oil content in the grease can be stably supplied to the rolling surface by the capillary action of the thickener fiber. .
Examples of monoamines other than aliphatic monoamines and alicyclic monoamines include aromatic monoamines.
Examples of the aliphatic monoamine include hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, stearylamine, and oleylamine. Among these, octylamine is preferable.
Examples of the alicyclic monoamine include cyclohexylamine.
Examples of the aromatic monoamine include aniline and p-toluidine, and among these, p-toluidine is preferable.

  In the present invention, the urea-based thickener is contained in an amount of 3 to 9% by weight, preferably 5 to 9% by weight, based on the entire grease. If the blending amount is less than 3% by weight, the base oil retention capacity is not sufficient, and especially at the beginning of rotation, a large amount of oil is separated at one time and grease leakage occurs, resulting in a shortened bearing durability life. On the other hand, if the blending amount is 9% by weight or more, the amount of the base oil is relatively small, the oil supply ability is insufficient, the lubrication is insufficient early, and the bearing durability life is similarly shortened.

  In addition, the grease may contain known grease additives 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 include solid lubricants, metal sulfonates, rust inhibitors such as polyhydric alcohol esters, friction reducers such as organic molybdenum, oil 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. The content of these additives is preferably individually 0.05% by weight or more of the total amount of grease, and the total amount is preferably in the range of 0.15 to 10% by weight of the total amount of grease. In particular, when the total amount exceeds 10% by weight, not only an effect commensurate with the increase in content can be expected, but also the content of other components becomes relatively small, and these additives aggregate in the grease, Undesirable phenomena such as an increase in torque may be caused.

  The present invention will be further described below with reference to test examples, but the present invention is not limited thereby. Table 1 shows data on the density (15 ° C.) and kinematic viscosity (40 ° C.) of the base oil used in each example and each comparative example. Further, the consistency shown in Table 1 represents the 60-degree penetration penetration measured according to JISK2220 5.3, and the surface tension of the base oil at 25 ° C. is a value measured with a Dunui simple surface tension meter.

Examples 1 to 5, Comparative Example 1, Comparative Example 2 and Comparative Example 5
4,4'-diphenylmethane diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Millionate MT, hereinafter referred to as MDI) is dissolved in half of the base oil shown in Table 1 at 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.
While stirring the solution in which the MDI is dissolved, the solution in which the monoamine is dissolved is added thereto, and then the reaction is continued by stirring at 100 ° C. to 120 ° C. for 30 minutes to form a diurea compound in the base oil, and a grease sample is obtained. Obtained. The density, kinematic viscosity, and surface tension measurement results of the base oil used are shown in Table 1. In addition, the consistency and centrifugal oil separation of the obtained grease samples were measured, and they were subjected to the centrifugal oil separation test and the normal temperature high speed grease test shown below to measure the centrifugal oil separation and the normal temperature high speed grease life time. The measurement results are also shown in Table 1.

<Centrifuge oil separation test>
Using a centrifuge, a 50 g grease sample was placed in a centrifuge tube, and the oil separation by centrifugation was calculated using the following formula when acceleration of 23000 G was applied for 7 hours at 40 ° C.
(Centrifugal oil separation,%) = (1−thickener concentration before test / thickener concentration after test) × 100

<Normal temperature high speed grease test>
A test sample was prepared in a deep groove ball bearing (6204) by enclosing 0.14 g (about 3% by volume of the total bearing space) of the grease sample with the aim of the rolling surface and sealing it without contact. The test bearing was loaded with an axial load of 670 N and a radial load of 67 N, and the inner ring was rotated at a rotational speed of 15000 rpm in a normal temperature environment. The time until seizure was measured as the grease life time. The dmN value, which is the product of the pitch circle diameter (mm) and the rotational speed (rpm), of the bearing in this durability test is 520,000. The temperature of the bearing outer ring, which is a fixed ring, during the tests of the examples and comparative examples was about 70 ° C.

Comparative Example 3 and Comparative Example 4
A base oil and lithium stearate were blended in the proportions shown in Table 1 to obtain a grease sample. The same items as in Example 1 were measured for the base oil and grease samples used. The results are also shown in Table 1.

As shown in Table 1, in the grease-filled motor bearing used in the present invention, the above-mentioned grease composition is (1) a base oil having a kinematic viscosity at 40 ° C. of 15 to 30 mm ² / sec. (2) The monoamine component of the urea-based thickener is at least one monoamine selected from aliphatic monoamines and alicyclic monoamines, and is based on the total monoamine (3) The base oil has a surface tension of 25 mN / m or more and a density of 0.95 g / cm ³ or less, and the base oil is a synthetic hydrocarbon oil, ester oil or alkyl. It turns out that it is preferable that they are diphenyl ether oil and these mixed oil.

The grease-enclosed bearing for a motor of the present invention comprises a grease composition encapsulated in the bearing and a base oil having a kinematic viscosity of 15 to 30 mm ² / sec at 40 ° C. and 3 weights of a predetermined urea thickener. % To less than 9% by weight, so even when using a small amount of grease, it is excellent in the ability to supply oil to the raceway surface under high-speed rotation while maintaining load resistance when used at relatively low temperatures. Therefore, motors for industrial machines or information devices such as motors for ventilation fans, blower motors for fuel cells, cleaner motors, fan motors, servo motors, stepping motors, starter motors for automobiles, electric power steering motors, tilt motors for steering adjustment It can be suitably used as a grease sealed bearing for motors of motors for electrical equipment such as wiper motors and power window motors.

It is sectional drawing of a deep groove ball bearing. It is sectional drawing of the structure of a motor.

Explanation of symbols

1 Deep groove ball bearing (grease bearing for motor)
DESCRIPTION OF SYMBOLS 2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Seal member 7 Grease composition 8a Both-end opening 8b Both-end opening 9 Jacket 10 Stator 11 Rotating shaft 12 Winding 13 Rotor 14 Commutator 15 Brush holder 16 Brush 17 End frame

Claims (6)

A grease-filled bearing for a motor that supports a rotor of a motor, the grease-filled 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 grease composition around the rolling elements A seal member for sealing the inner ring and the outer ring at both ends in the axial direction,
The grease composition comprises a base oil and a urea-based thickener,
The base oil has a kinematic viscosity at 40 ° C. of 15 to 30 mm ² / sec,
The urea-based thickener is obtained by reacting a polyisocyanate component and a monoamine component, and the monoamine component contains at least one monoamine selected from an aliphatic monoamine and an alicyclic monoamine in an amount of 50 mol relative to the total monoamine. A grease-enclosed bearing for motors, wherein the urea-based thickener is blended in an amount of 3 wt% to less than 9 wt% with respect to the entire grease. The grease-enclosed bearing for a motor according to claim 1, wherein the base oil has a surface tension of 25 mN / m or more and a density of 0.95 g / cm ³ or less.   3. The grease-filled bearing for a motor according to claim 1, wherein the base oil is at least one oil selected from a synthetic hydrocarbon oil, an ester oil, and an alkyl diphenyl ether oil.   4. The grease-filled bearing for motors according to claim 3, wherein the grease-filled bearing for motors is a deep groove ball bearing.   The grease-filled bearing for a motor according to any one of claims 1 to 4, wherein the grease-filled bearing for a motor is used in a temperature environment of less than 150 ° C.   The grease-filled bearing for a motor according to any one of claims 1 to 5, wherein the grease-filled bearing for a motor is used for a motor of an industrial machine or an information device.

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