JP2015028351A - Grease-packed bearing for inverter driving motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grease-packed bearing for an inverter driving motor, whose damage caused by corrosion can be effectively suppressed, and which is excellent in an acoustic property.SOLUTION: A grease-packed bearing 1 for an inverter driving motor is a bearing which supports via a main shaft 11, a roller 13 being a rotor of the inverter driving motor driven by inverter control. The grease-packed bearing 1 includes: an inner ring 2; an outer ring 3; a plurality of rolling elements 4 interposed between the inner and outer rings; grease encapsulated into peripheries of the rolling elements; and a seal member for sealing the grease which is arranged at both-end openings of the inner ring and the outer ring. The grease is obtained by compounding an additive containing a prescribed amount of an amine acid of an alkyl aromatic sulfonic acid into base grease composed of base oil and a thickening agent.

Description

  The present invention relates to a grease-filled bearing for an inverter drive motor, and more particularly to a grease-filled bearing used for an inverter drive motor for industrial machinery or automotive electrical equipment.

  Electrical components and accessories in automobiles, motors in industrial machines, and the like are required to be downsized, high performance, and high output year by year, and usage conditions are becoming stricter. For these, sealed deep groove ball bearings (rolling bearings) are generally used, and are often used in inverter-controlled motors. Inverter motor usage is increasing due to convenience such as simplified and high-speed maintenance and variable support by controlling inverters, and this trend is expected to continue in the future. Inverter control adjusts voltage and frequency. Rolling bearings built into inverter-driven motors cause damage called "electric corrosion" that occurs when high-frequency current flows from the inverter circuit on the rolling surface. I may receive it.

  In order to prevent such a problem from occurring, conventionally, it has been proposed to avoid damage caused by electrolytic corrosion by forming and insulating the rolling elements constituting the bearing with ceramics (Patent Document 1 and Patent Document 1). 2). Further, Patent Document 3 proposes a rolling bearing that uses an ionic liquid as a base oil of grease and carbon black as a thickener, thereby reducing the volume resistivity of the grease itself and preventing electrolytic corrosion. (See Patent Document 3). In addition, it is conceivable to prevent electrolytic corrosion by adding an additive capable of forming a passive film (oxide film) or the like in the grease to be sealed.

Japanese Patent No. 2991834 Japanese Patent No. 2934697 JP 2006-250323 A

  However, when a ceramic bearing member is used as in Patent Documents 1 and 2, the product cost is very high, and it is difficult to say that this is a general measure. Moreover, in patent document 3, in order to reduce the volume resistivity of the grease to be enclosed, combinations of base oil and thickener are limited, and it may be difficult to ensure a sufficient lubrication life.

  In addition, in an inverter drive motor bearing, it is also important to prevent the occurrence of vibrations and abnormal noise, that is, to have excellent acoustic characteristics. Preventing wear due to electrolytic corrosion leads to prevention of the vibration and abnormal noise. However, when an additive that can form a passive film (oxide film) or the like is added to the grease to be sealed to prevent electrolytic corrosion, the type of additive may be used even if electrolytic corrosion itself can be prevented by the oxide film. Depending on the case, vibration or abnormal noise may occur.

  The present invention has been made to cope with such problems, and an object of the present invention is to provide a grease-filled bearing for an inverter drive motor that can effectively suppress damage due to electrolytic corrosion and has excellent acoustic characteristics.

  The grease sealed bearing for the inverter drive motor of the present invention is a bearing that supports the rotor of the inverter drive motor driven by inverter control, and includes an inner ring, an outer ring, and a plurality of rolling elements interposed between the inner and outer rings, Grease sealed around the rolling elements and a seal member for sealing the grease provided at both axial opening portions of the inner ring and the outer ring are provided. An additive is blended in a base grease composed of a funnel, and the additive contains at least an amine salt of an alkyl aromatic sulfonic acid, and the amine salt of the alkyl aromatic sulfonic acid is added to 100 parts by weight of the base grease. On the other hand, 0.05-10 weight part is contained.

  The amine constituting the amine salt of the alkyl aromatic sulfonic acid is an amine having a plurality of amino groups. In particular, the amine salt of the alkyl aromatic sulfonic acid is diethylene triamine salt or ethylenediamine salt of dinonylnaphthalene sulfonic acid.

  The base oil is at least one oil selected from ester oils and poly-α-olefin (hereinafter also referred to as “PAO”) oils, and the thickener includes a urea compound.

  The inner ring, the outer ring, and the rolling element are made of a ferrous metal.

  The grease-enclosed bearing for an inverter drive motor of the present invention is formed by encapsulating a base grease composed of a base oil and a thickener with a grease blended with an amine salt of an alkyl aromatic sulfonic acid at a predetermined ratio as an additive. Damage (electric corrosion) on the rolling surface caused by high-frequency current flowing from the inverter circuit is suppressed, and long-term use is possible. In addition, it has excellent acoustic characteristics and can prevent vibration and abnormal noise. Furthermore, iron-based metal materials can be used for the inner ring, outer ring, and rolling elements that are bearing members, and it is not necessary to use ceramics or the like.

It is the schematic sectional drawing and the partially expanded view of the motor which used the grease-filled bearing for inverter drive motors of this invention for the bearing for output motors. It is sectional drawing of a deep groove ball bearing.

  An embodiment of the present invention will be described with reference to FIG. An example of a grease-filled bearing for an inverter drive motor that supports the rotor of the motor is shown in FIG. FIG. 1A is a schematic cross-sectional view of a motor using the bearing as a bearing for an output motor, and FIG. 1B is an enlarged view of a portion A in FIG. As shown in FIGS. 1A and 1B, the motor 10 rotates a load object by attaching a belt 18 to a pulley 17 interlocked with the main shaft 11. A rotor 13 is attached to the main shaft 11, a pulley 17 is attached to one end thereof, and a belt 18 for rotating an air conditioning fan or the like is attached. The main shaft 11 is rotatably supported on the flange 14 by a first radial ball bearing 15 and a second radial ball bearing 16 attached to both ends of the rotor 13. A stator 12 is fixed to the flange 14 so as to face the rotor 13. Further, a wave spring washer 19 is located between the flange 14 and the second radial ball bearing 16 to apply a preload. The first radial ball bearing 15 and the second radial ball bearing 16 are grease sealed bearings for an inverter drive motor according to the present invention, and support the rotor 13 that is a rotor via the main shaft 11.

  1 (a) and 1 (b), a method of preloading using a spring is employed, and a spring, a wave spring washer 19 and the like are positioned between the flange 14 and the second radial ball bearing 16 to apply preload. It shows the state. As shown in FIG. 1B, the second radial ball bearing 16 holds an inner ring 2 as an inner member, an outer ring 3 as an outer member, a plurality of balls 4 as rolling elements, and a plurality of balls 4. The cage 5 is provided. Further, seal members (not shown) are provided at both axial opening portions of the inner ring 2 and the outer ring 3, and predetermined grease (described later) is sealed around the balls 4. The first radial ball bearing 15 has the same structure as the second radial ball bearing 16. In this embodiment, deep groove ball bearings are used as the first radial ball bearing 15 and the second radial ball bearing 16. In addition to deep groove ball bearings, for example, angular ball bearings, cylindrical roller bearings, tapered roller bearings, self-aligning roller bearings, needle roller bearings, thrust cylindrical roller bearings, thrust tapered roller bearings, thrust needles A tapered roller bearing, a thrust self-aligning roller bearing, or the like can also be employed.

  The details of the above grease-filled bearing for the inverter drive motor (deep groove ball bearing) will be described with reference to FIG. FIG. 2 is a sectional view of the bearing. The grease-filled bearing 1 for an inverter drive motor is a deep groove ball bearing, and an inner ring 2 having an inner ring rolling surface 2a on an outer circumferential surface and an outer ring 3 having an outer ring rolling surface 3a on an inner circumferential surface are disposed concentrically. A plurality of balls 4 that are rolling elements are arranged between the rolling surface 2a and the outer ring rolling surface 3a. Moreover, the holder | retainer 5 which hold | maintains the ball | bowl 4 which is these several rolling elements is provided. Further, a seal member 6 fixed to the outer ring 3 or the like is provided in the axially opposite end openings 8 a and 8 b of the inner ring 2 and the outer ring 3. A predetermined grease 7 to be described later is enclosed at least around the balls 4.

  Bearing members such as an inner ring, an outer ring, a rolling element, and a cage can be formed of a ferrous metal material. In the present invention, it is not necessary to use a ceramic material for these bearing members in order to prevent electrolytic corrosion by the action of grease described later. The ferrous metal material is an arbitrary material generally used in the bearing field. For example, high-carbon chromium bearing steel (SUJ1, SUJ2, SUJ3, SUJ4, SUJ5, etc .; JIS G 4805), carburized steel (SCr420, SCM420 etc .; JIS G 4053), stainless steel (SUS440C etc .; JIS G 4303), high speed steel (M50 etc.), cold rolled steel, etc. are mentioned.

  The grease used for the grease-sealed bearing for the inverter drive motor of the present invention is obtained by blending an amine salt of an alkyl aromatic sulfonic acid as an essential additive with a base grease composed of a base oil and a thickener. By blending an amine salt of an alkyl aromatic sulfonic acid, it is adsorbed on the bearing rolling surface and a stable film is formed. This coating can reduce wear during energization and prevent electrolytic corrosion. When rolling elements and bearing rings made of iron-based metal and rolling members and cages, etc., are in rolling contact / sliding while in contact with grease, there is almost no oil film on the contact surface between the members, and partial In some cases, the boundary lubrication conditions are such that the surfaces of the metals directly touch each other. Thus, even when the oil film becomes thin under severe conditions (boundary lubrication conditions) on the sliding surface, the above-mentioned film can be formed in which the amine salt of alkylaromatic sulfonic acid easily enters the portion.

As the sulfonic acid constituting the amine salt of alkyl aromatic sulfonic acid that can be used in the present invention, the aromatic group may be either a monocyclic or polycyclic condensed ring, and examples thereof include benzene, naphthalene, anthracene, phenanthrene and the like. It is done. Among these, since it is excellent in thermal stability, an alkylbenzene sulfonic acid represented by the following formula (1) in which the aromatic group is benzene, and an alkyl naphthalene sulfonic acid represented by the following formula (2) in which the aromatic group is naphthalene. Is preferred. Alkyl naphthalene sulfonic acids such as dinonyl naphthalene sulfonic acid are preferred because they have particularly high thermal stability.

  In the formulas (1) and (2), R and R ′ are each an alkyl group (aliphatic hydrocarbon group), and n is an integer of 1 to 3. 1-30 are preferable, as for carbon number in R and R ', 6-18 are more preferable, and 8-10 are especially preferable.

  Examples of the amine constituting the amine salt of the alkyl aromatic sulfonic acid include ethylamine, trimethylamine, ethylenediamine, diethylenetriamine and the like. Among these, it is preferable to use ethylenediamine or diethylenetriamine having a plurality of amino groups. When ethylenediamine or diethylenetriamine is used as the amine, iron ions can be sandwiched by chelating action to prevent exposure of the new surface of the iron-based metal, and it can easily form a coating that has high adsorption power to the metal surface and can reduce wear due to electrolytic corrosion. Cheap.

The amine salt of alkyl aromatic sulfonic acid may be used alone or in combination of two or more. The amine salt of alkyl aromatic sulfonic acid is preferably liquid at room temperature and operating temperature. Further, it may be dispersed in an aliphatic solvent, mineral oil or the like. By using a liquid material, there is no adverse effect on the acoustic characteristics, and even when the oil film of the sliding portion becomes thin under severe conditions, it is easy to enter the sliding portion and form a film. The kinematic viscosity of the amine salts of alkyl aromatic sulfonic acid, preferably 10 to 100 mm ² / s at 100 ° C., more preferably 20~85mm ² / s at 100 ° C..

  Examples of commercially available amine salts of alkyl aromatic sulfonic acids include, for example, King's NA-SUL DTA (diethylenetriamine salt of dinonylnaphthalenesulfonic acid), NA-SUL EDS (ethylenediamine salt of dinonylnaphthalenesulfonic acid), etc. Is mentioned.

  In addition, when an alkali metal salt or alkaline earth metal salt of the sulfonic acid is used in place of the amine salt of the alkyl aromatic sulfonic acid, wear due to electrolytic corrosion may not be prevented, as shown in Comparative Examples described later. . For this reason, it is preferable not to contain the alkali metal salt or alkaline-earth metal salt of alkyl aromatic sulfonic acid.

  The mixing ratio of the amine salt of the alkyl aromatic sulfonic acid is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease (base oil and thickener). When the compounding ratio of the amine salt of the alkyl aromatic sulfonic acid is less than 0.05 parts by weight, there is a possibility that abrasion due to electrolytic corrosion cannot be sufficiently prevented. Moreover, when the compounding ratio of the amine salt of alkyl aromatic sulfonic acid exceeds 10 parts by weight, the reactivity with iron becomes too high, and abnormal wear such as corrosion wear may occur. Preferably it is 0.1-10 weight part, More preferably, it is 0.5-5 weight part, More preferably, it is 1-3 weight part.

  The base oil that can be used in the present invention is not particularly limited, and those commonly used in the field of ordinary grease can be used. For example, mineral oil such as spindle oil, refrigeration oil, turbine oil, machine oil, dynamo oil, highly refined mineral oil, liquid paraffin oil, polybutene oil, GTL oil synthesized by Fischer-Tropsch method, PAO oil, alkylnaphthalene oil, fat Hydrocarbon synthetic oils such as cyclic compounds, or natural oils, polyol ester oils, phosphate ester oils, polymer ester oils, aromatic ester oils, carbonate ester oils, diester oils, polyglycol oils and other ester oils, silicones Non-hydrocarbon synthetic oils such as oil, polyphenyl ether oil, alkyldiphenyl ether oil, alkylbenzene oil, and fluorinated oil. These may be used alone or in combination of two or more.

  Among these, it is preferable to use at least one oil selected from PAO oil and ester oil because of excellent heat resistance, lubricity, and low noise.

The kinematic viscosity of the base oil (in the case of a mixed oil, the kinematic viscosity of the mixed oil) is preferably 10 to ²⁰⁰ mm ² / s at 40 ° C. More preferably, it is 10-120 mm < ² > / s.

  The thickener that can be used in the present invention is not particularly limited, and those commonly used in the field of grease can be used. For example, soap-type thickeners such as metal soaps and composite metal soaps, and non-soap-type thickeners such as benton, silica gel, urea compounds and urea / urethane compounds can be used. Examples of metal soaps include lithium soap, sodium soap, calcium soap, and aluminum soap. Examples of metal composite soaps include lithium complex soap, calcium complex soap, and aluminum complex soap. Urea compounds and urea / urethane compounds include diurea. Examples thereof include compounds, triurea compounds, tetraurea compounds, other polyurea compounds, and diurethane compounds. Among these, it is preferable to use a urea compound or lithium soap because of its low noise and heat resistance and low cost.

  A urea compound 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. Moreover, an aliphatic monoamine, an alicyclic monoamine, and an aromatic monoamine can be used for a monoamine component. Aliphatic monoamines include hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, stearylamine, oleylamine and the like. Examples of the alicyclic monoamine include cyclohexylamine. Aromatic monoamines include aniline, p-toluidine and the like.

  Among these urea compounds, it is preferable to use an aliphatic diurea compound using an aromatic diisocyanate as a polyisocyanate component and an aliphatic monoamine as a monoamine component because it has heat resistance, lubricity and low noise.

  Base grease can be obtained by blending thickener with base oil. A base grease using a urea compound as a thickener is prepared by reacting the polyisocyanate component and the monoamine component in a base oil. The blending ratio of the thickener in 100 parts by weight of the base grease is 1 to 40 parts by weight, preferably 3 to 25 parts by weight. If the content of the thickener is less than 1 part by weight, the thickening effect is reduced, making it difficult to form a grease. If the content exceeds 40 parts by weight, the obtained base grease becomes too hard and the desired effect is difficult to obtain. Become.

  As a method for preparing the grease, first, an amine salt of an alkyl aromatic sulfonic acid is blended with the base oil, and a thickener is prepared using the base oil. After preparing the grease, a dispersion is added thereto. Any of the methods may be used. Since the amine salt of the alkyl aromatic sulfonic acid contains an amino group, the base salt is prepared by reacting the polyisocyanate component and the monoamine component in the base oil, and then the amine salt of the alkyl aromatic sulfonic acid is added. Is a preferred method.

  The grease penetration (JIS K 2220) is preferably in the range of 200 to 350. When the consistency is less than 200, oil separation is small and there is a risk of poor lubrication. On the other hand, if the consistency exceeds 350, the grease is soft and easily flows out of the bearing, which is not preferable.

  In the above grease, as long as the object of the present invention (especially acoustic properties) is not impaired, a known antioxidant other than an alkyl aromatic sulfonic acid amine salt, a metal deactivator, a viscosity index improver, You may contain additives, such as a rust preventive agent, an oiliness agent, and a friction reducing agent. Among these, it is preferable that the additive contains at least one antioxidant selected from a phenol-based antioxidant, an amine-based antioxidant, and zinc dithiophosphate. In particular, zinc dithiophosphate (zinc dialkyldithiophosphate) is essential, and it is preferable to use either a phenol-based antioxidant or an amine-based antioxidant in combination. Moreover, it is preferable that the mixture ratio of these antioxidants is 0.5-5 weight part in total with respect to 100 weight part of total amounts of a base oil and a thickener.

  Additives preferably not included include alkali metal salts of inorganic acids and alkaline earth metal salts of inorganic acids. Here, examples of the inorganic acid include phosphoric acid (orthophosphoric acid), hydrochloric acid, nitric acid, sulfuric acid, boric acid and the like. Examples of the alkali metal and alkaline earth metal include lithium, sodium, potassium, calcium, strontium, barium and the like. Is mentioned. Specific examples include tricalcium phosphate (calcium salt of orthophosphoric acid). Moreover, it is preferable not to contain the metal salt of molybdate.

  The present invention will be specifically described with reference to examples and comparative examples, but is not limited to these examples.

Examples 1 to 7, Comparative Examples 1 to 7
A monoamine that dissolves 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI) in half of the base oil shown in Table 1 in the proportions shown in each table, and that is twice the equivalent of MDI in the remaining half of the base oil. Was dissolved. 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 with stirring at 100 to 120 ° C. for 30 minutes to produce a diurea compound in the base oil to obtain a base grease. Each additive such as an amine salt of an alkyl aromatic sulfonic acid was added to the mixture at a blending ratio shown in each table, 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.

  The obtained grease was subjected to the following acoustic measurement and electrical wear test. Test methods and test conditions are shown below. The results are shown in Table 1.

<Acoustic measurement>
A deep groove ball bearing (bearing dimensions: φ8 × φ22 × 7 (mm)) filled with 0.1 g of the grease shown in Table 1 was prepared, and an axial load of 7.8 N was applied to the bearing and operated at 1800 rpm for 30 seconds. Vibration value G (RMS value) was measured. Three-stage evaluation was performed as follows.
◎: Vibration value is less than 25 mG ○: Vibration value is less than 50 mG ×: Vibration value is 50 mG or more

<Electrical wear test>
1 g of the grease obtained in each example was sealed in the rolling bearing (51106), and the rotation speed was 2600 rpm with a current of 2 A applied between the outer ring and the inner ring at room temperature (25 ° C.) and an axial load of 1450 N. After 24 hours, the amount of wear of the inner and outer rings due to electrolytic corrosion was measured in terms of weight loss. Three-stage evaluation was performed as follows.
A: Wear amount is less than 1 mg ○: Wear amount is less than 2 mg X: Wear amount is 2 mg or more

  As shown in Table 1, it can be seen that each example in which an amine salt of an alkyl aromatic sulfonic acid is blended has a small amount of wear in the current wear test and can effectively prevent electrolytic corrosion and has excellent acoustic characteristics. .

  The grease-filled bearing for the inverter drive motor of the present invention suppresses damage (electric corrosion) caused by high-frequency current flowing from the inverter circuit, can be used for a long time, and has excellent acoustic characteristics. It can be suitably used as a bearing used in an inverter-controlled motor.

1 Grease-sealed bearing for inverter drive motor 2 Inner ring 3 Outer ring 4 Ball (rolling element)
DESCRIPTION OF SYMBOLS 5 Cage 6 Seal member 7 Grease 8a Opening part 8b Opening part 10 Motor 11 Motor spindle 12 Stator 13 Rotor (rotor)
14 Flange 15 First ball bearing 16 Second ball bearing 17 Pulley 18 Belt 19 Wave spring washer

Claims (5)

A grease sealed bearing for an inverter drive motor that supports a rotor of an inverter drive motor driven by inverter control,
The grease-sealed bearing is provided in the inner ring, the outer ring, a plurality of rolling elements interposed between the inner and outer rings, grease sealed around the rolling element, and openings in both axial ends of the inner ring and the outer ring. And a sealing member for sealing the grease,
The grease comprises an additive added to a base grease comprising a base oil and a thickener, and the additive contains at least an amine salt of an alkyl aromatic sulfonic acid, and the amine salt of the alkyl aromatic sulfonic acid Is contained in an amount of 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease.   The grease-enclosed bearing for an inverter drive motor according to claim 1, wherein the amine constituting the amine salt of the alkyl aromatic sulfonic acid is an amine having a plurality of amino groups.   The grease-sealed bearing for an inverter drive motor according to claim 2, wherein the amine salt of the alkyl aromatic sulfonic acid is diethylenetriamine salt or ethylenediamine salt of dinonylnaphthalenesulfonic acid.   The said base oil is at least 1 oil chosen from ester oil and poly-alpha-olefin oil, The said thickener contains a urea compound, The claim | claim of Claim 1, Claim 2 or Claim 3 characterized by the above-mentioned. Grease-filled bearing for inverter drive motor.   5. The grease-filled bearing for an inverter drive motor according to claim 1, wherein the inner ring, the outer ring, and the rolling element are made of an iron-based metal.

Images