JP2016194348A - Rolling bearing - Google Patents

Abstract

[Problem] By always making the bearing conductive, it is possible to ensure stable conductive performance, suppress hydrogen infiltration caused by potential decomposition of grease and moisture due to static electricity generated between the belt and pulley, and insulation breakdown caused by potential difference between the outer and inner rings, and actually suppress peeling accompanied by white structure change caused by hydrogen embrittlement. [Solution] A conductive contact-type seal 21 is provided between the outer ring 2 and the inner ring 7, and a slinger 39 is provided on the outside of the seal 21, and the seal 21 is provided with a fourth lip 35 that contacts the slinger 39. Conductive grease 45 is filled in the internal space of the bearing and contacts both the outer ring 2 and the inner ring 7, and conductive grease 45 is also sealed between the conductive seal 21 and the conductive slinger 39 and contacts both the seal 21 and the slinger 39, so that electricity is always flowing. [Selected Figure] Figure 1

Description

  The present invention relates to, for example, a rolling bearing for an electrical component of an automobile or an auxiliary machine for an automobile engine.

  For example, in a rolling bearing for an automotive auxiliary machine such as an alternator bearing, a plurality of rolling elements (balls) are incorporated between an outer ring and an inner ring, and grease is sealed through a sealing device. Ball bearings are mainly used.

  Such rolling bearings for automobile auxiliary machines are often used with high loads and high speed rotation, and in such an environment, friction is caused between the raceway surface of the outer and inner rings and the balls that are rolling elements. It is possible that When friction is generated in this way, a new surface is formed by friction, the grease is chemically decomposed and a large amount of hydrogen is generated, and this hydrogen penetrates into the outer ring or inner ring, resulting in hydrogen embrittlement (cracking). Peeling with white tissue changes may be caused.

  In addition, such rolling bearings for automotive accessories are used under severe conditions such as an environment where muddy water, rainwater, etc. are likely to be splashed, so that hydrogen is generated when water enters the bearings. In the same manner as described above, peeling accompanied by a change in white structure due to hydrogen embrittlement (cracking) may be caused.

  Note that static electricity is generated between the belt and the pulley when the pulley is driven by the belt. At this time, if strong vibrations are applied, the outer and inner rings are electrically connected and a large potential difference is generated between the outer and inner rings. The grease is mixed in the grease and water is electrolyzed to promote the generation of hydrogen ions. It is more likely to happen.

  As a prior art proposed for the purpose of suppressing peeling accompanied by a white structure change caused by hydrogen embrittlement of a rolling bearing, for example, as shown in Patent Document 1, a conductive grease is enclosed. And those using a conductive cage as disclosed in Patent Document 2 have been proposed.

  However, in Patent Document 1 and Patent Document 2, the conductivity changes depending on the grease distribution state and the contact state between the cage and the outer inner ring, so that stable conductive characteristics cannot be obtained, which is more severe. In a water environment, there is a concern that water may enter the bearing due to insufficient sealing performance, and white peeling due to hydrogen embrittlement caused by hydrogen due to electrolysis of the moisture may occur.

  In addition, the prior art according to Patent Document 3, which uses a conductive seal and conductive grease to provide conductivity, and further uses ceramic balls as rolling elements to reduce the centrifugal force of the balls and reduce the occurrence of new surfaces due to friction. Proposed.

  However, ceramic balls are extremely expensive, and are not practical for rolling bearings for automobiles that are particularly required to be low in cost.

JP 2002-195277 A JP 2002-286040 A JP 2011-231785 A

  The present invention has been made in view of the above-described problems of the prior art, and the object of the present invention is to ensure stable conductivity performance by always imparting conductivity to the bearing, and the belt and pulley. Suppresses hydrogen intrusion caused by the potential decomposition of grease and moisture due to static electricity generated between them, and dielectric breakdown (spark) due to potential difference between the outer and inner rings, and suppresses peeling with white structure change caused by hydrogen embrittlement An object of the present invention is to provide a rolling bearing that makes this possible in practice.

In order to achieve such a problem, the present invention comprises an outer ring and an inner ring that are arranged to be relatively rotatable,
An outer ring side raceway surface provided in the outer ring;
An inner ring side raceway surface provided in the inner ring;
A plurality of rolling elements incorporated between the outer ring side raceway surface and the inner ring side raceway surface;
A pair of contact-type sealing seals disposed between the outer ring and the inner ring and sealing the interior of the bearing;
A slinger fixed to the inner ring is provided on the axially outer side of one of the pair of hermetic seals,
In rolling bearings,
The hermetic seal is a conductive hermetic seal,
The slinger is a slinger having conductivity,
In the sealing seal, a lip member that contacts the slinger is protruded on the surface facing the slinger,
Conductive grease is sealed in the bearing inner space surrounded by the outer ring, the inner ring, and the pair of sealing seals,
A rolling bearing is characterized in that conductive grease is sealed in a sealed space surrounded by the hermetic seal, the slinger, and the inner ring.

  According to the present invention, by providing a slinger having conductivity, the water penetration resistance and dust penetration resistance into the bearing are improved, and both the slinger and the sealing seal have conductivity, and the outer ring and By encapsulating conductive grease in the bearing inner space surrounded by the inner ring and a pair of hermetic seals, and in the sealed space surrounded by the seal seal, slinger and inner ring, respectively, by always giving the bearing conductivity, Because stable conductive performance is ensured, the hydrogen penetration caused by the potential decomposition of grease and moisture due to static electricity generated between the belt and pulley and the dielectric breakdown (spark) caused by the potential difference between the outer and inner rings are suppressed, resulting in hydrogen embrittlement. It was possible to suppress the peeling accompanied with the white texture change.

It is a schematic longitudinal cross-sectional view of this invention rolling bearing.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, this embodiment is only one embodiment of the present invention, and is not construed as being limited thereto, and can be appropriately modified within the scope of the present invention. In the present embodiment, the rolling ball bearing illustrated as an embodiment of the present invention will be described. However, the present invention is not limited to the rolling ball bearing, and other bearing types may be employed.

  The rolling ball bearing 1 is disposed so as to be relatively rotatable, and includes an outer ring 2 having an outer ring side raceway surface 3 continuously provided on an inner periphery, an inner ring 7 having an inner ring side raceway surface 9 continuously provided on an outer periphery, Between the outer ring side raceway surface 3 and the inner ring side raceway surface 9, a plurality of rolling elements 17 incorporated via a cage 19 and the outer ring 2 and the inner ring 7 are arranged to seal the inside of the bearing. It includes at least a pair of seal seals 21 and 21 and grease 45 sealed inside the bearing, and is configured to include a slinger 39 on the outer side in the axial direction of at least one seal seal 21 (see FIG. 1).

  The hermetic seal 21 is formed of a core metal 37 formed in a substantially annular shape and an elastic portion 22 that covers the core metal 37 and is integrally formed in a substantially annular shape, and the outer ring 23 side is sealed on the outer ring 1 side. The groove 5 is fixedly disposed.

The hermetic seal 21 has a disc portion 25 that is continuously formed from the outer peripheral portion 23 and a lip portion 27 that is continuously formed from an inner diameter end portion of the disc portion 25. The first lip 29 having the smallest diameter, the second lip 31 having a larger diameter than the first lip 29, and the third lip 33 having a larger diameter than the second lip 31 are integrally formed.
In the present embodiment, a fourth lip 35 having a larger diameter than that of the third lip 33 is integrally formed on the outer surface of the disc portion 25 near the outer peripheral portion 23.

The first lip 29 is directed inward in the axial direction so that the first lip 29 is in sliding contact with the radial annular surface portion 15 of the step portion 11 provided at the end portion of the outer peripheral surface of the inner ring 7 from the outside in the axial direction with a predetermined allowance. It is formed to project in an annular shape.
The second lip 31 is arranged on the radially outer side of the first lip 29, and protrudes in an annular shape toward the inner side in the axial direction so as to be in sliding contact with the radial annular surface portion 15 from the outer side in the axial direction with a predetermined tightening allowance. An annular region 49 surrounded by the first lip 29, the second lip 31, and the radial direction annular surface portion 15 is formed.
The third lip 33 is formed so as to project in an annular shape inward in the axial direction from the inner diameter end of the disc portion 25, and is a non-contact seal region between the outer peripheral surface of the inner ring 7 and the step portion 11. (Labyrinth gap) 47 is formed.

The fourth lip 35 is formed to project from the outer surface of the disk portion 25 in an annular shape outward in the axial direction, and is in sliding contact with the inner surface in the axial direction of the annular portion 43 of the slinger 39 with a predetermined allowance. Yes.
The shape of the sealing seal 21, the number of lips, the sliding portion of each lip, and the like are not limited to the illustrated shapes.

  The elastic portion 22 of the hermetic seal 21 including the first lip 29, the second lip 31, the third lip 33, and the fourth lip 35 is configured by adding a conductive substance to a soft elastic material such as rubber. It functions as a sexual seal.

In the present embodiment, the elastic portion 22 having conductivity is assumed to be formed by mixing a desired amount of carbon black and conductive fibers as conductive particles in an arbitrary rubber material, for example.
As the rubber material, nitrile rubber, acrylic rubber, fluorine rubber, silicon rubber or the like generally used as a sealing material can be appropriately selected.

  As the conductive particles, conductive metal oxides such as graphite, indium / tin oxide, and antimony / tin oxide can be used instead of the carbon black, and these materials can be appropriately selected. As the conductive fiber, stainless fiber, carbon fiber (carbon fiber, carbon tube), or conductive fiber plated on potassium titanate (for example, manufactured by Otsuka Chemical Co., Ltd.) can be used. Further, any thickness and length of the conductive fiber can be selected.

  The total amount of conductive particles and conductive fibers mixed in the rubber material is preferably 20 to 120% by mass with respect to the rubber material. When the total amount of the conductive particles and the conductive fibers is less than 20% by mass, sufficient conductivity cannot be obtained, and when 120% by mass or more is contained, sufficient elasticity cannot be obtained.

  As described above, the conductive metal seal 37 is formed by covering the cored bar 37 with the conductive elastic portion 22 in which carbon black which is conductive particles and conductive fibers are mixed in a desired amount. The connection is reinforced with conductive fibers, and as a result, the volume resistivity representing the magnitude of the electrical insulation resistance can be reduced to about 0.1 to 1 Ω · cm.

The slinger 39 is a cylindrical portion 41 that is press-fitted into the axial annular surface portion 13 that constitutes the step portion 11 of the inner ring 7, and a circle that is formed continuously from the axially outer end of the cylindrical portion 41 radially outward. It is comprised with the ring part 43. FIG.
The slinger 39 is made of a conductive metal and functions as a conductive slinger.
The shape of the slinger 39 is not particularly limited to the illustrated shape, and can be changed in design within the scope of the present invention.

  The grease 47 is conductive grease and is enclosed in a bearing internal space surrounded by the outer ring 2, the inner ring 7, and the pair of sealing seals 21, 21, and the annular region 49, the sealing seal 21, the slinger 39, and the inner ring. 7 is also enclosed in a sealed space surrounded by 7.

  The base oil used for the conductive grease 47 is not particularly limited, and any oil that is normally used as a base oil for lubricating oil can be used. However, no abnormal noise is generated at low temperature startup due to insufficient low temperature fluidity, and particularly considering durability against high temperatures exceeding 200 ° C., the kinematic viscosity at 40 ° C. is preferably 30 to 250 mm 2 / sec, more preferably A synthetic lubricating oil of 50 to 200 mm2 / sec is desirable. When the kinematic viscosity at 40 ° C. is less than 30 mm 2 / sec, it is difficult to form a sufficient oil film at a high temperature exceeding 200 ° C., and metal contact is likely to occur and early seizure is likely to occur. On the other hand, when the kinematic viscosity at 40 ° C. exceeds 250 mm 2 / sec, the agitation resistance of the grease increases and the amount of heat generation increases, so that each element of the rolling bearing (inner ring, outer ring, rolling element) expands and the internal gap Decreases, and abnormal wear and seizure are likely to occur. Moreover, it is inferior in the fluidity | liquidity at the time of low temperature, and it becomes difficult to fully satisfy | fill the low temperature starting property as a rolling bearing for motor vehicle electrical components or engine auxiliary machines.

Examples of the synthetic lubricating oil include hydrocarbon oils, aromatic oils, ester oils, ether oils, and the like. Examples of the hydrocarbon oil include normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, poly-α-olefin such as 1-decene and ethylene co-oligomer, and hydrides thereof. Examples of the aromatic oil include alkylbenzenes such as monoalkylbenzene and dialkylbenzene, and alkylnaphthalenes such as monoalkylnaphthalene, dialkylnaphthalene and polyalkylnaphthalene. Examples of the ester oil include dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, and methyl acetyl cinnolate, or trioctyl trimellitate. , Aromatic ester oils such as tridecyl trimellitate, tetraoctyl pyromellitate, trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol belargonate, etc. Examples thereof include polyol ester oils, and complex ester oils that are oligoesters of polyhydric alcohols and mixed fatty acids of dibasic acids and monobasic acids. Examples of the ether oil include polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether, or monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, and monoalkyl. Examples thereof include phenyl ether oils such as tetraphenyl ether and dialkyl tetraphenyl ether.
Other synthetic lubricating base oils include tricresyl phosphate, silicone oil, perfluoroalkyl ether and the like. These synthetic lubricating oils can be used alone or as a mixture, and are adjusted to the above-mentioned preferable kinematic viscosity.

In addition, mineral oil and natural oil-based lubricating oil can be used in combination as long as high temperature durability is not impaired. In addition, as mineral oil-based lubricating oil, use one obtained by appropriately combining mineral oil with vacuum distillation, degreasing, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, clay refining, hydrorefining, etc. Can do.
Examples of natural oil-based lubricating oils include beef tallow, lard, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil, and other oils and hydrides thereof.

Then, in order to remove the potential difference between the inner and outer rings of the bearing and prevent the peeling phenomenon, conductive powder is added. The conductive powder is not particularly limited, but carbon powder such as carbon black or carbon nanotube can be suitably used in consideration of maintaining conductivity up to a high temperature and not deteriorating the lubricity of grease.
Carbon black preferably has an average particle size of 5 μm or less, and more preferably 2 μm or less. Most preferably, an average particle diameter of 10 to 300 nm is used. Such carbon black is also available from the market, and examples thereof include Ketjen Black EC and Ketjen Black EC600JD manufactured by Lion Akzo. Carbon nanotubes having a diameter of 15 nm or less and a length of 5 μm or less, including C60 and C70 fullerenes, can be suitably used. Preferably, those having a diameter of 10 nm or less and a length of 2 μm or less are used.
Such carbon nanotubes can also be obtained from the market, and examples thereof include carbon nanofiber VGCF manufactured by Showa Denko KK.

  The amount of the conductive powder added is preferably 0.5 to 5% by mass of the total amount of the grease composition. If the addition amount is 0.5% by mass or less, the effect of addition cannot be obtained, and if it exceeds 5% by mass, the fluidity of the grease deteriorates and the seizure life may be reduced, which is not preferable. Further, if the average particle diameter or length exceeds 2 μm, the acoustic performance of the bearing may be affected.

  In addition, in order to further improve the lubrication performance, an antiwear agent, an antioxidant, a rust inhibitor, an extreme pressure agent, an oiliness agent, a metal deactivator, a viscosity index improver, a cleaning dispersant, etc. are used alone as necessary. In addition, or by appropriately adding to the grease in combination, bearing damage can be suppressed, a stable conductive life can be imparted to the grease, and the peeling life can be extended. And in order to suppress the fall over time of conductivity over a longer period, it is preferable to use an antiwear agent and an oily agent in combination. In particular, when a phosphite ester is used as an antiwear agent and a carboxylic acid anhydride is used as an oiliness agent, the effect of suppressing a decrease in conductivity over time is particularly excellent.

Therefore, according to this embodiment, the conductive grease 45 is in contact with both the outer ring 2 and the inner ring 7, and the conductive sealing seal 21 is in contact with both the outer ring 2 and the inner ring 7. The sealing seal 21 and the conductive slinger 39 are also in contact with each other by the fourth lip 35, and the conductive grease sealed between the conductive sealing seal 21 and the conductive slinger 39 is sealed. Both the seal 21 and the slinger 39 are in contact with each other and are always electrically energized to ensure the conductivity of the bearing.
Further, since the seal seal 21 is provided with the fourth lip 35 that comes into contact with the slinger 39, the conductive grease 45 filled between the seal seal 21 and the slinger 39 is prevented from being scattered, and the inside of the bearing is prevented. It has the effect of improving water / foreign substance penetration.

  INDUSTRIAL APPLICABILITY The present invention can be used for rolling bearings used in automobile electrical components, car air conditioner electromagnetic clutches, and the like.

DESCRIPTION OF SYMBOLS 1 Rolling bearing 2 Outer ring 3 Outer ring side raceway surface 5 Seal groove 7 Inner ring 9 Inner ring side raceway surface 17 Rolling element 19 Cage 21 Seal seal 37 Core metal 39 Slinger 45 Grease

Claims (1)

An outer ring and an inner ring disposed so as to be relatively rotatable;
An outer ring side raceway surface provided in the outer ring;
An inner ring side raceway surface provided in the inner ring;
A plurality of rolling elements incorporated between the outer ring side raceway surface and the inner ring side raceway surface;
A pair of contact-type sealing seals disposed between the outer ring and the inner ring and sealing the interior of the bearing;
A slinger fixed to the inner ring is provided on the axially outer side of one of the pair of hermetic seals,
In rolling bearings,
The hermetic seal is a conductive hermetic seal,
The slinger is a slinger having conductivity,
In the sealing seal, a lip member that contacts the slinger is protruded on the surface facing the slinger,
Conductive grease is sealed in the bearing inner space surrounded by the outer ring, the inner ring, and the pair of sealing seals,
A rolling bearing characterized in that conductive grease is sealed in a sealed space surrounded by the hermetic seal, the slinger, and the inner ring.

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