JP2010156392A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing which hardly causes the leakage of a lubricant even if used under the condition of high-speed rotation, and which is rolled at low torque. <P>SOLUTION: The deep-groove ball bearing comprises: an inner ring 1; an outer ring 2; a plurality of rolling bodies 3 which are rollingly arranged between both raceway surfaces 1a, 2a; and non-contact sealing devices 5, 5 with external peripheral ends 5a attached to the outer ring 2, and internal peripheral ends 5b opposed to the external peripheral surface of the inner ring 1 with a clearance. The lubricant G which is obtained by forming base oil into a gel by using an amino-acid system compound or a benzylidene sorbitol dielectric is arranged in an internal space of the bearing which is surrounded by the inner ring 1, the outer ring 2, and the sealing devices 5, 5. Furthermore, fluorine grease containing fluorine oil and fluorine resin is arranged at the clearance which is formed between the internal peripheral ends 5b of the sealing devices 5 and the external peripheral surface of the inner ring 1, and in the vicinity of the clearance. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rolling bearing.

In recent years, the usage conditions of rolling bearings have become more severe, and for example, the rotational speed has been increased more and more. In order to increase the rotational speed, it is necessary to reduce the rotational torque of the rolling bearing. In addition, when the rolling bearing is rotated at a high speed, the lubricant disposed in the bearing inner space of the rolling bearing is likely to leak to the outside, and this needs to be prevented.
For example, Patent Document 1 discloses a rolling bearing in which a shield which is a non-contact type sealing device is attached to an outer ring, and an inner peripheral side end of the shield is opposed to a seal surface of the inner ring with a gap. Yes. And since the oil repellent is adhered to the seal surface of the inner ring and the inner peripheral side end of the shield facing the seal surface, the lubricant put in the bearing internal space is repelled by the oil repellent and the outside of the bearing Leakage is suppressed.

In Patent Document 2, soft grease (grease having a JIS consistency of No. 000 to No. 1) is disposed near the center portion (lubricated part) of the bearing internal space, and hard grease (JIS consistency) is disposed on the outside thereof. No. 2 to No. 5 grease) is disclosed. With the above-described configuration, the lubrication performance is improved and the grease is prevented from leaking.
JP-A-11-62972 JP 59-11398

  However, although the rolling bearing disclosed in Patent Document 1 has an excellent effect of preventing lubricant leakage under low-speed rotation conditions, the oil repellent easily peels off under high-speed rotation conditions. It was difficult to maintain. Further, the rolling bearing disclosed in Patent Document 2 has a risk of grease leakage because the outer grease is softened due to shearing by the seal lip and mixing with the inner grease under high-speed rotation conditions.

  Therefore, the present invention solves the above-described problems of the prior art, and provides a rolling bearing that is less likely to leak lubricant from the bearing internal space and has a low torque even when used under high-speed rotation conditions. And

  In order to solve the above problems, the present invention has the following configuration. That is, the rolling bearing according to the present invention includes an inner ring, an outer ring, a plurality of rolling elements arranged to freely roll between a raceway surface of the inner ring and a raceway surface of the outer ring, the inner ring, and the outer ring. A non-contact type sealing device that is attached to one of the bearing rings and faces the other bearing ring with a gap therebetween, wherein the inside of the bearing is surrounded by the inner ring, the outer ring, and the sealing device In the space, a lubricant obtained by gelling a base oil with an amino acid compound or a benzylidene sorbitol derivative is disposed, and in the gap formed between the sealing device and the other race ring and in the vicinity thereof, Fluorine grease containing fluorine oil and fluororesin is arranged.

  Even if the rolling bearing of the present invention is used under high-speed rotation conditions, the lubricant hardly leaks from the bearing inner space and has a low torque.

Embodiments of a rolling bearing according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial longitudinal sectional view showing a structure of a deep groove ball bearing which is an embodiment of a rolling bearing according to the present invention.
The deep groove ball bearing shown in FIG. 1 is rotatable between an inner ring 1 having a raceway surface 1a on an outer peripheral surface, an outer ring 2 having a raceway surface 2a facing the raceway surface 1a on an inner peripheral surface, and both raceway surfaces 1a and 2a. A plurality of rolling elements (balls) 3 disposed on the inner ring 1, a cage 4 that holds the plurality of rolling elements 3 between the inner ring 1 and the outer ring 2, and a non-cover that substantially covers the opening of the gap between the inner ring 1 and the outer ring 2. Contact-type sealing devices 5 and 5 (for example, steel shields or rubber seals). In addition, the holder | retainer 4 does not need to be provided.

  The sealing device 5 is a substantially annular member, and an outer peripheral end portion 5 a is attached to both axial end portions of the inner peripheral surface of the outer ring 2. In FIG. 1, the outer peripheral end 5 a of the sealing device 5 is caulked and fitted into grooves formed at both axial end portions of the inner peripheral surface of the outer ring 2. The inner peripheral end 5 b of the sealing device 5 faces the outer peripheral surface of the inner ring 1 with a gap. The outer ring 2 corresponds to “one race ring (a race ring to which a sealing device is attached)” which is a constituent requirement of the present invention, and the inner ring 1 corresponds to “the other race ring (sealing device) which is a constituent requirement of the present invention. Corresponds to an orbital ring facing with a gap). The inner peripheral end 5b of the sealing device 5 may be attached to the inner ring 1 and the outer peripheral end 5a may be opposed to the inner peripheral surface of the outer ring 2 with a gap.

  In the bearing inner space surrounded by the inner ring 1, the outer ring 2, and the sealing devices 5, 5, a lubricant G that lubricates between the raceway surfaces 1 a and 2 a and the rolling surface 3 a of the rolling element 3. Is arranged. This lubricant G is a gel lubricant formed by gelling a base oil with a gelling agent. The type of base oil is not particularly limited, but the type of gelling agent is an amino acid compound or a benzylidene sorbitol derivative.

  On the other hand, a gap formed between the inner peripheral end 5b of the sealing device 5 and the outer peripheral surface of the inner ring 1 and its vicinity (in FIG. 1, this gap and its vicinity are circled and denoted by reference symbol A). Hereinafter, a combination of the gap and the vicinity thereof may be referred to as a seal lip vicinity portion), and fluorine grease (not shown) is disposed. This fluorine grease is a grease that uses fluorine oil as a base oil and fluorine resin as a thickener.

  Lubricant G using an amino acid compound or a benzylidene sorbitol derivative as a gelling agent has a very small amount of gelling agent. Therefore, when shearing force is applied, it is easy to change from gel to oily (concentration 380 or more). There is a tendency to change and flow. Therefore, when a shearing force is applied by the rotation of the deep groove ball bearing, the lubricant G located in the vicinity of the raceway surfaces 1a and 2a and the rolling surface 3a of the rolling element 3 quickly changes to oil, and the deep groove It is used for ball bearing lubrication. As a result, the deep groove ball bearing has a low torque even when it rotates under a high-speed rotation condition (for example, a rotation speed of 80% or more of the allowable rotation speed of the rolling bearing during grease lubrication), and the rotation torque stabilizes early. .

  On the other hand, fluorine grease is disposed in the gap formed between the inner peripheral end 5 b of the sealing device 5 and the outer peripheral surface of the inner ring 1 and in the vicinity thereof. Therefore, even if the deep groove ball bearing rotates under high-speed rotation conditions and a shearing force is applied from the inner peripheral end 5b of the sealing device 5, there is almost no possibility that the fluorine grease leaks to the outside of the deep groove ball bearing. Further, even if the lubricant G changed to oily due to the application of shear force flows in the vicinity of the seal lip, the lubricant G is repelled so as not to be mixed with the fluorine grease. There is almost no risk of leakage.

If fluorine grease is not disposed in the vicinity of the seal lip, the lubricant G that flows to the vicinity of the seal lip by high speed rotation and adheres to the inner peripheral end 5b of the sealing device 5 There is a risk of softening due to the shearing force applied from the portion 5b and leakage from the inside space of the bearing to the outside of the deep groove ball bearing.
In addition, general greases using metal soaps and urea compounds as thickeners are easily mixed with the lubricant G. If these general greases are arranged in the vicinity of the seal lip, the shearing force is applied. There is a risk that the oil changes into oil and is mixed with the lubricant G flowing in the vicinity of the seal lip. Therefore, when the deep groove ball bearing is rotated for a long time, general grease arranged in the vicinity of the seal lip is softened and may leak to the outside of the deep groove ball bearing together with the lubricant G.

  Furthermore, when only fluorine grease is sealed in the bearing internal space, there is almost no risk of fluorine grease leaking out of the deep groove ball bearing even if the deep groove ball bearing is used under high speed rotation conditions. Since the fluidity is poor and the lubrication performance is inferior as compared with greases based on olefin oil, there is a problem that wear is likely to occur in deep groove ball bearings. When wear powder generated by wear is mixed into the fluorine grease, the rotational torque of the deep groove ball bearing may increase.

  Furthermore, since fluorine grease is more expensive than general greases containing metal soap or urea compounds as a thickener, deep groove ball bearings become expensive when only fluorine grease is sealed in the bearing internal space. There is also a problem of end.

Here, the lubricant G will be described in detail.
[About gelling agent]
The amino acid compound and the benzylidene sorbitol derivative have a high ability to gel oil, and can easily form a gel-like substance in a small amount (by blending several mass%) as compared with a general gelling agent.

  For example, NLGI No. The amount of the gelling agent necessary for obtaining a hardness of 2 (concentration 265 to 295) is 10 to 30% by mass of a general gelling agent (for example, a soap-based gelling agent or a urea-based gelling agent). On the other hand, in the case of an amino acid compound or a benzylidene sorbitol derivative, the content is 2 to 5% by mass. Since the amount of the gelling agent is as small as 5% by mass or less, the lubricant G easily becomes oily and flows when a shearing force is applied.

The type of amino acid compound is not particularly limited as long as it is dispersed in a base oil to form a gel, but N-2-ethylhexanoyl-L-glutamic acid dibutylamide or N-lauroyl -L-glutamic acid-α, γ-n-dibutylamide is preferred.
Similarly, the type of benzylidene sorbitol derivative is not particularly limited as long as it is dispersed in a base oil to form a gel, but dibenzylidene sorbitol, ditrilidene sorbitol, as well as asymmetric dialkyl benzylidene sorbitol Is preferred. These gelling agents may be used alone or in combination of two or more.

  The content of the gelling agent is preferably 1% by mass or more and 10% by mass or less of the lubricant G. If the content of the gelling agent is less than 1% by mass, the lubricant G in a state where no shearing force is applied is too soft, and there is a possibility that a problem may occur in the sealing operation in the bearing internal space. On the other hand, if the content of the gelling agent is more than 10% by mass, the lubricant G in a state where no shear force is applied is too hard, which may cause a problem in the sealing operation in the bearing internal space. Further, even when a shearing force is applied, the oil does not change to an oil having sufficient fluidity, and the rotational torque when rotating under high-speed rotation conditions may not be sufficiently low. In order to make such inconvenience more difficult to occur, the content of the gelling agent is more preferably 2% by mass or more and 5% by mass or less.

[About base oil]
The type of base oil is not particularly limited as long as it is gelled by a gelling agent, and oils generally used as lubricating oils can be used without any problem. For example, mineral oil-based lubricating oil, synthetic oil-based lubricating oil, and natural oil-based lubricating oil can be used.
As the mineral oil-based lubricating oil, preferred is a mineral oil purified by appropriately combining vacuum distillation, solvent removal, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, white clay purification, hydrorefining, and the like. Synthetic oil-based lubricating oils include aliphatic hydrocarbon oils (for example, poly α-olefin oil), aromatic hydrocarbon oils, ether oils, ester oils, and glycol oils. Furthermore, examples of the natural oil-based lubricating oil include beef fat, pork fat, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil, and other oils and hydrides thereof. These may be used alone or in combination of two or more.

[Additives]
Furthermore, in order to further improve various performances of the lubricant G, additives generally used for lubricants such as grease may be added. For example, antioxidants, rust inhibitors, antiwear agents, extreme pressure agents, oiliness improvers, metal deactivators and the like can be mentioned.
Examples of the antioxidant include amine-based antioxidants, phenol-based antioxidants, sulfur-based antioxidants, zinc dithiophosphate, and zinc dithiocarbamate. Examples of the rust preventive include sulfonic acid metal salts, ester-based rust preventives, amine-based rust preventives, naphthenic acid metal salts, and succinic acid derivatives. Examples of extreme pressure agents include phosphorus extreme pressure agents, zinc dithiophosphate, and organic molybdenum. Examples of oiliness improvers include fatty acids and animal and vegetable oils. Examples of the metal deactivator include benzotriazole.

  These additives may be used independently and may be used in combination of 2 or more types as appropriate. The total content of additives in the lubricant G is not particularly limited as long as it does not impair the object of the present invention.

  Next, the fluorine grease will be described in detail. Although the kind of fluorine oil which is a base oil of fluorine grease is not particularly limited, fluoropolyether oil such as perfluoropolyether oil (PFPE) is preferable. Fluoropolyether oil includes linear and branched ones, either one of which may be used, or a mixture of both. Further, the kinematic viscosity of the fluorine oil is not particularly limited, and those having a general kinematic viscosity as the base oil of the grease can be used without any problem.

  In addition, the type of fluororesin that is a thickener for the fluorine grease is not particularly limited, but polytetrafluoroethylene (PTFE) or other ethylene-based non-polymers that are fluorinated in whole or in part with tetrafluoroethylene. Copolymers with saturated hydrocarbon monomers are preferred. One kind of fluororesin may be used alone, but a plurality of kinds of fluororesins may be used in combination.

A powdery fluororesin is mixed with a base oil to form a fluorine grease, but the particle shape of the powder is not particularly limited, and examples thereof include a spherical shape, a polyhedral shape (for example, a cube, a rectangular parallelepiped), and a needle shape.
In order to further improve various performances of the fluorine grease, additives generally used for lubricants such as grease may be added. The blending degree of such fluorine grease is NLGI No. It is preferable that it is 1-3.

  In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in the present embodiment, a deep groove ball bearing has been described as an example of a rolling bearing, but the present invention can be applied to various types of rolling bearings. For example, radial rolling bearings such as angular contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing.

〔Example〕
The present invention will be described more specifically with reference to the following examples. A grease leakage test and a torque test were performed using a bearing (inner diameter: 25 mm, outer diameter: 62 mm, width: 17 mm) having substantially the same configuration as the deep groove ball bearing shown in FIG.
The following four types of lubricants are prepared, and the clearance formed in the bearing inner space and between the inner peripheral end of the shield and the outer peripheral surface of the inner ring and the vicinity thereof (the aforementioned seal lip vicinity) Any one of the four types of lubricants was disposed (see Tables 1 and 2).

Gel lubricant A: ester oil as the base oil (kinematic viscosity at 40 ° C. is 31 cSt) and N-2-ethylhexanoyl-L-glutamic acid dibutylamide as the gelling agent. The content of the gelling agent is 5% by mass of the lubricant.
Gel-like lubricant B: Monool-type glycol oil (kinematic viscosity at 40 ° C. is 31 cSt) as the base oil, and dibenzylidene sorbitol as the gelling agent. The content of the gelling agent is 4% by mass of the lubricant.

Fluorine grease: Perfluoropolyether oil as the base oil (kinematic viscosity at 40 ° C. is 60 cSt) and PTFE as the thickener.
Urea grease: A base oil using an ester oil (kinematic viscosity at 40 ° C. is 31 cSt) and a urea compound having an alicyclic hydrocarbon group as a thickener.

  The standard amount of lubricant used in the deep groove ball bearing used for the test is 35% by volume of the volume of the bearing internal space. When this amount is expressed by mass, due to the difference in the density of the lubricant, it becomes 3.4 g for the above-mentioned gel lubricants A and B and urea grease, and 7 g for the fluorine grease. In this test, 80% of the standard amount of lubricant used is disposed in the bearing internal space, and 20% is disposed in the vicinity of the seal lip.

  For example, when gel lubricant A or B is used in the bearing inner space and fluorine grease is used in the vicinity of the seal lip, 2.72 g of gel lubricant A or B is sealed in the bearing inner space. 1.4 g of fluorine grease is disposed in the vicinity of the lip. When fluorine grease is used for both, 5.6 g is disposed in the bearing internal space and 1.4 g is disposed in the vicinity of the seal lip. Further, when gel lubricant A, B or urea grease is used for both, 2.72 g is disposed in the bearing internal space and 0.68 g is disposed in the vicinity of the seal lip.

Next, the grease leakage test will be described. The test bearing was rotated for 20 hours under the following conditions, the amount of leaked lubricant was measured, and the grease leakage rate was calculated. The results are shown in Tables 1 and 2. The grease leakage rates shown in Tables 1 and 2 are shown as relative values when the grease leakage rate of Comparative Example 1 is 1.
Rotational speed: 10000 min ⁻¹ (90% of the allowable rotational speed of deep groove ball bearing during grease lubrication)
Radial load: 98N
Axial load: 98N
Test temperature: 80 ° C

  Next, the torque test will be described. The test bearing was rotated under the following conditions, and an average value of torque for 10 seconds between 295 and 305 seconds after the start of rotation was calculated as a torque value. The results are shown in Tables 1 and 2. The torque values shown in Tables 1 and 2 are shown as relative values when the torque value of Comparative Example 1 is 1.

Rotational speed: 3000 min ^-1
Radial load: 29.4N
Axial load: 294N
Test temperature: Room temperature Explains the results of grease leakage test and torque test. As can be seen from Tables 1 and 2, Examples 1 and 2 are provided with a gel-like lubricant that easily changes to oil when a shearing force is applied, in the bearing internal space, and fluorine that is difficult to mix with the gel-like lubricant. Since grease is provided in the vicinity of the seal lip, the grease leakage rate is as low as 0.2 or less and the torque value is as low as 1.2 or less even when used under high-speed rotation conditions.

In Comparative Example 2, the gel-like lubricant is provided in the inner space of the bearing, so that the torque value is as low as 1.2 or less, but urea grease that may be mixed with the gel-like lubricant is used as a seal lip. Since it was provided in the vicinity, the grease leakage rate was higher than in Examples 1 and 2, exceeding 0.2.
In Comparative Example 3, fluorine grease was used both in the bearing internal space and in the vicinity of the seal lip, so the grease leakage rate was low but the torque value was high. Comparative Example 4 is the same as Comparative Example 3.

It is a fragmentary longitudinal cross-section which shows the structure of the deep groove ball bearing which is one Embodiment of the rolling bearing which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 1a Raceway surface 2 Outer ring 2a Raceway surface 3 Rolling element 5 Sealing device 5b Inner peripheral edge G Lubricant

Claims (1)

An inner ring, an outer ring, a plurality of rolling elements arranged in a freely rolling manner between the raceway surface of the inner ring and the raceway surface of the outer ring, and the other attached to one raceway ring of the inner ring and the outer ring In a rolling bearing provided with a non-contact type sealing device that faces the raceway ring with a gap therebetween,
A lubricant formed by gelling a base oil with an amino acid compound or a benzylidene sorbitol derivative is disposed in a bearing inner space surrounded by the inner ring, the outer ring, and the sealing device, and the sealing device and the other raceway. A rolling bearing characterized in that fluorine grease containing fluorine oil and fluorine resin is disposed in the gap formed between the ring and the vicinity thereof.

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