JP2005121102A - Seal structure for bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce frictional resistance of a contact part without problems and to achieve a long service life in a seal structure of a bearing presenting a contact-type seal structure having high sealability. <P>SOLUTION: In this seal structure for the bearing where a part between a pair of relatively-rotated members 22, 20 is sealed by the contact of ring-shaped seal lips 23a-23c of a seal member 23 fixed to one member 22 and a peripheral face of the other member 20, spherical fine particles 30 are added to the grease G acting on the contact part S of the seal lips 23a-23c and the peripheral face of the other member 20, and the seal member 23 is made out of a rubber material including the spherical fine particles 30. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a bearing seal structure, and more specifically, a pair of relatively rotating members is sealed by contact between a ring-shaped seal lip of a seal member fixed to one member and a peripheral surface of the other member. The present invention relates to a bearing seal structure.

  In a ball bearing which is an example of a bearing, lubricating oil such as grease is provided for lubricating a rolling portion between the ball and the inner ring and the outer ring. And many of them are provided with a seal member for sealing between the outer ring and the inner ring in order to prevent the leakage of the lubricating oil and obtain good durability (bearing with seal).

  The structure in which the seal member is provided on the bearing is roughly classified into a non-contact type labyrinth seal structure and a contact type lip seal structure. In the former seal structure, one ring (outer ring) on the fixed side is fixedly equipped with a ring-shaped plate (steel plate, synthetic resin plate, etc.), and the other ring (inner ring) on the inner periphery and the rotation side ) To form a labyrinth. In the latter seal structure, a seal member is fixedly mounted on one ring (outer ring) on the fixed side, and a ring-shaped seal lip (generally made of rubber) formed on the inner peripheral side is on the rotating side. The other ring (inner ring) is pressed against the outer periphery.

  Comparing these two seal structures, the former is inferior in sealing performance but has no rotational resistance, whereas in the latter, the rotational resistance is somewhat generated but excellent in sealing performance. Has characteristics. Therefore, when the sealing performance is important, the latter sealing structure is adopted. As an example of such a contact-type seal structure, the one shown in Patent Document 1 is known, and a seal member is fixed to a front housing which is a stationary member, and a plurality of ring-shaped seal lips of the seal member The inner peripheral portion of the rotating shaft and the outer peripheral surface of the rotating shaft are brought into contact with each other for sealing.

In the contact-type seal structure, it is a problem to improve the durability of the seal member. In the seal structure shown in the above-mentioned Patent Document 1, in order to improve the durability against the wear of the seal contact portion and extend the life of the seal device, the seal lip tip and the outer peripheral surface of the rotary shaft are provided. A diamond-like carbon film (diamond-like hard carbon film) capable of greatly reducing the friction coefficient is formed.
JP 2000-122242 A

  In other words, by forming a diamond-like carbon film at the contact portion between the lip and the rotating shaft, while maintaining good sealing performance, the friction coefficient is greatly reduced to reduce rotational resistance due to friction and increase the length. Although it was intended to extend the service life, it has been found that the effect is not shown as expected.

  That is, as shown in FIG. 8, if the surface of the seal lip or the rotating shaft 50 has undulations or irregularities 51, the diamond-like carbon film 40 is coated following the undulations or irregularities 51. The diamond-like carbon film 40 is not in contact with a smooth surface. As a result, the surface pressure of the contact portion hardly decreases, and thereby the effect of reducing frictional resistance and improving durability is not so much exhibited.

  Accordingly, an object of the present invention is to provide a bearing seal structure having the above-described contact-type seal structure having a good sealing property, which can reduce the frictional resistance of the contact portion without inconvenience so as to extend the service life. is there.

The structure of claim 1 is a bearing seal structure in which a pair of relatively rotating members is sealed by contact between a ring-shaped seal lip of a seal member fixed to one member and a peripheral surface of the other member.
Lubricating oil acting on a contact portion between the seal lip and the peripheral surface of the other member is provided, and spherical oil is added to the lubricating oil.

The structure of claim 2 is a bearing seal structure in which a pair of relatively rotating members is sealed by contact between a ring-shaped seal lip of a seal member fixed to one member and a peripheral surface of the other member.
The seal member is formed of a rubber material to which true spherical fine particles are added.

The structure of claim 3 is the structure of claim 1,
The seal member is formed of a rubber material to which true spherical fine particles are added.

The configuration of claim 4 is a bearing seal structure in which a pair of relatively rotating members is sealed by contact between a ring-shaped seal lip of a seal member fixed to one member and a peripheral surface of the other member.
A film layer made of a diamond-like hard carbon film is formed at the contact portion of the seal lip with the other member, and a fine crack-like part is formed at a portion where the film layer is formed. It is characterized by that.

The structure of claim 5 is the structure of claim 4,
Lubricating oil acting on a contact portion between the seal lip and the peripheral surface of the other member is provided, and spherical oil is added to the lubricating oil.

The configuration of claim 6 is any one of claims 1 to 5,
A film layer made of a diamond-like hard carbon film is formed at a contact portion of the other member with the seal lip.

  In the bearing seal structure according to claim 1, although described in detail in the examples, the action of filling the fine undulations and irregularities generated in the other member with spherical fine particles in addition to the lubricating oil occurs, These undulations and irregularities can be virtually eliminated to make a smooth surface. As a result, the frictional resistance due to the contact between the seal lip and the other member is greatly reduced, and it is possible to prolong the service life by drastically reducing the friction coefficient while providing a contact-type seal structure with excellent sealing performance.

  In the bearing seal structure according to claim 2, since spherical particles are added to the rubber material of the seal member, even when the lubricating oil is lost in the contact portion with the other member (oil film breakage), The spherical particles having a low friction coefficient come into contact with the other member, so that an increase in friction is suppressed, and a light relative rotation state between one member and the other member can be maintained.

  In the bearing seal structure according to the third aspect, both of the effect by the structure of the first aspect and the effect by the structure of the second aspect can be obtained.

  The bearing seal structure according to claim 4 will be described in detail in the embodiment. However, a fine crack-like portion in the centripetal direction is formed in advance on the portion of the seal lip where the diamond-like hard carbon film is formed. Therefore, the lubricating oil can be introduced into the cracked portions only by assembling one member and the other member, and the contact portion can be smoothed. As a result, the effect of reducing the friction coefficient by the film layer can be exhibited immediately after assembly, and a bearing seal structure that can achieve both good sealing performance and long life at a high level can be realized.

  In the bearing seal structure according to claim 5, since spherical fine particles are added to the lubricating oil, not only the lubricating oil but also the spherical fine particles enter the cracked portion so that the smoothing of the surface is further promoted. Become. As a result, there is an advantage that the friction coefficient can be further reduced, and the effect of reducing the friction (rotational resistance) of the bearing and the effect of improving the sealing performance can be further enhanced.

  In the bearing seal structure according to claim 6, in the case where a film layer made of a diamond-like hard carbon film is formed on the other member in contact with the seal lip, the friction coefficient becomes extremely small, and the sliding is performed at a low surface pressure. Since it can be moved, the friction (rotational resistance) of the bearing can be greatly reduced and the sealing performance is also improved. Since the surface of the other member is in a smooth state, there is also an advantage that the action of scraping off the seal lip does not occur.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an angular type bearing (bearing) 9 that rotatably supports a drive wheel such as a tire of an automobile, and a structure around it. FIG. 2 is an enlarged cross-sectional view of the bearing 9 and the built-in inner and outer seal rings 16 and 17.

  As shown in FIG. 1, the bearing 9 is for constituting a wheel and rotates an inner ring 5 in which a hub (not shown) on the rotation side is fitted with respect to a hub carrier 8 on the non-rotation side. The outer ring 13 that is a part of the hub carrier 8, the inner ring 5, and the balls (rotating balls) 15 that are rolling elements arranged in two rows on the left and right sides are provided between the outer ring 13 and the inner ring 5. And retainers 1 and 2 for arranging these balls 15 at equal intervals in the circumferential direction.

  As shown in FIG. 2, an inner seal ring 16 composed of a pair of a fixed side seal ring 18 and a rotation side seal ring 19 is provided between the outer ends of the outer ring 13 and the inner ring 5 in the left-right direction. An outer seal ring 17 consisting of a pair of a fixed seal ring 25 and a rotary seal ring 26 is provided between the end portions of the two.

  Reference numeral 3 denotes mounting bolts for mounting and fixing the hub carrier 8 also serving as the outer ring 13 to, for example, a support member 14 on the vehicle body side, and a plurality of mounting bolts are provided at equal intervals in the circumferential direction. A mounting hole 4 is formed at the center of the inner ring 5 for inserting and mounting the hub or the shaft portion of the constant velocity joint. The inner and outer seal rings 16 and 17 prevent the lubricating oil such as grease filled in the ball 15 portion from flowing out to the outside and prevent dust such as dust and foreign matter from flowing into the ball 15 portion from the outside.

  A magnetic sensor 24 fixed to the hub carrier 8 via the mounting stay 6 is provided at a position near the side of the inner seal ring 16, and the tone provided to the magnetic sensor 24 and the inner seal ring 16. The wheel 21 constitutes a rotational speed detecting encoder 10 that can detect the rotational speed of the wheel, that is, the inner ring 5 per unit time. Reference numeral 7 denotes a lead wire connected to the magnetic sensor 24.

  As shown in FIGS. 2 and 3, the inner seal ring 16 is provided between the inner end portion of the outer ring 13 and the inner end portion of the inner ring 5, and is fitted and supported by the inner end portion of the outer ring 13. It is configured as a combined seal ring with a tone wheel, which includes a fixed side seal ring 18 and a rotary side seal ring 19 that is fitted and supported on the inner end of the inner ring 5.

  The rotary side seal ring 19 is made of a metal plate such as a rolled steel plate or a stainless steel plate, and has an L-shaped cross section that is externally supported by the end portion of the inner ring 5 and an annular inner core (also referred to as a slinger) 20. And a tone wheel 21 fitted and supported on the inner cored bar 20. The inner cored bar 20 is fitted to the inner ring 5 from the fitting cylinder part 20a and from one end (right end in FIG. 2) of the fitting cylinder part 20a toward the fixed seal ring 18 (toward the outer ring 13 side). And a first standing wall portion 20b that protrudes.

  The tone wheel 21 detects the relative rotational speeds of the seal rings 18 and 19 on the fixed side and the rotary side. The tone wheel 21 is a first wheel to be mounted on the outer side surface (the right side surface in FIG. 2) of the first standing wall portion 20b. It is formed in a shape that wraps around the back side of the upright wall portion 20b and is attached using an adhesive. In other words, the outermost diameter portion 21a located outside the first standing wall portion 20b and the stop portion 21b slightly turned around to the back side (the left side in FIG. 2) of the first standing wall portion 20b have a substantially cross section. It is formed in a bowl-shaped ring.

  The stationary-side seal ring 18 includes an outer cored bar 22 having an L-shaped cross section and a ring shape as a whole, and a rubber seal member 23. The outer metal core 22 includes a cylindrical fitting cylinder portion 22a that is fitted and supported on the inner peripheral surface of the outer ring 13 by press-fitting, and an inner ring 5 from an axial end (left end in FIG. 2) of the fitting cylinder portion 22a. And a ring-shaped second standing wall portion 22b bent inward in the diameter direction toward the outer peripheral surface. The inner diameter side end portion of the second standing wall portion 22b is bent so as to slightly approach the inner side (right side in FIG. 2).

  The seal member 23 is attached over the entire inner surface of the outer core bar 22 and has one or more (three in the illustrated example) lip pieces that are in pressure contact with the first core bar 20. 23a, 23b, and 23c. The first seal lip (side lip) 23a is pressed into contact with the first standing wall portion 20b, and the second seal lip (main lip) 23b and the third seal lip (grease lip) 23c are pressed against the fitting cylinder portion 20a. Will be touched. Generally, the seal member 23 is often integrated with the outer core metal 22 by baking adhesion. The seal member 23 is provided with a tip side proximity portion 27 and a root side proximity portion 28 so as to form a labyrinth r1 with the tone wheel 21.

  As shown in FIG. 2, the outer seal ring 17 is basically composed of the same components as the inner seal ring 16 except that the tone wheel 21 is not provided. In other words, the rotary side seal ring 26 composed only of the inner metal core 20 and the fixed side seal ring 25 which is exactly the same as the fixed side seal ring 18 of the inner seal ring 16 are configured.

  In the present invention, various measures for reducing the frictional resistance between the seal member 23 and the inner core metal 20 are made in the inner and outer seal rings 16 and 17. This will be described below.

  As shown in FIG. 3, the inner seal ring 16 is provided with grease (an example of lubricating oil) G that acts on a contact portion between the first to third seal lips 23 a to 23 c and the peripheral surface of the inner core metal 20. The grease G is added with spherical particles 30 (see FIG. 4). A necessary amount of these greases G is applied in advance before assembly.

  For example, at the contact portion S between the second seal lip 23b and the fitting cylinder portion 20a, as shown in the partially enlarged view of FIG. In addition to this, the action of the spherical fine particles 30 entering and filling occurs, so that the undulations and irregularities can be virtually eliminated to make a smooth surface. As a result, the frictional resistance due to the contact between the second seal lip 23b and the inner metal core 20 is greatly reduced, and while the contact type seal structure is excellent in sealing performance, the friction coefficient can be drastically reduced and the life can be extended. .

  Here, the material of the spherical fine particles 30 is preferably a material that does not dissolve in grease and is excellent in heat resistance. In addition to alumina and silica particles, CdS, CdSe, TiO2, BaTiO3, ZnO, Ag, Au, Pt, Ru, CoFe3O4, etc. are possible. That is, the true spherical fine particles 30 can be made of particles made of metal or other materials in addition to the ceramic porous true spherical fine particles.

  As the manufacturing method of the spherical fine particles 30, a method of combusting and synthesizing a metal powder such as alumina in an oxidizing gas stream (yield 30% or less), a liquid as a raw material is cooled under vacuum, and condensed under pressure. There is a method (yield 95% or more). The latter method is preferable to the former method in that the particle size distribution is small and mass productivity is excellent, and 95% of the produced particles can be accommodated in the target particle size. .

  Further, the diameter of the true spherical fine particles 30 is formed to be 100 nm to 30 μm. The surface of the spherical fine particles 30 is porous, and the polymer in the grease adheres to the particle surface with an oil-absorbing and geometrical surface roughness, which makes it feel like a marimo.

  That is, the spherical fine particles 30 added in the grease G enter between the particles on the metal surface in the fitting cylindrical portion 20a of the inner core metal 20 to make the metal surface smooth. Since the fine particles are spherical and the surface thereof has a marimo shape, there is also a preferable advantage that the action of scraping off the mating surfaces (in this case, the tip portions of the seal lips 23a to 23c) does not occur.

  As shown in FIG. 5, the seal structure of Example 2 is obtained by applying grease G to which true spherical fine particles 30 are added to contact portions S between the seal lips 23 a to 23 c and the peripheral surface of the inner core metal 20. The seal member 23 is made of a rubber material to which the spherical fine particles 30 are added. That is, in the seal structure shown in FIG. 3, the spherical particles 30 are added to the rubber material forming the seal member 23.

  If the spherical fine particles 30 are added to the rubber material of the seal member 23, the spherical fine particles 30 having a low friction coefficient are formed on the inner side even when the grease disappears at the contact portion S with the inner core 20 (oil film breakage). The contact with the metal core 20 has the advantage that the increase in friction is suppressed and the stationary seal ring 18 and the rotary seal ring 19 can smoothly rotate relative to each other. Of course, the above-described operation and effect by the structure of FIG. 3 can also be obtained.

  The rubber material for the seal member 23 includes NBR, ACM, FKM and the like.

  As shown in FIGS. 6 and 7, the seal structure of the third embodiment includes a contact portion S with the inner core metal 20 that is the tip of the first to third seal lips 23 a to 23 c, and each of the inner core metal 20. A film layer 40 made of a diamond-like hard carbon film is formed in the contact portion S with the seal lips 23a to 23c, and the tip portions of the seal lips 23a to 23c on which the film layer 40 is formed have fine particles. A crack (an example of a crack-like portion) 41 is formed. In addition, the grease G to which the spherical particles 30 are added is applied to each contact portion S.

  FIG. 7 is an enlarged view of portion A in FIG. A large number of cracks 41 are formed at the tip of the second seal lip 23 b, particularly the inner peripheral portion that comes into contact with the inner core metal 20. In use, the grease G containing the true spherical fine particles 30 in the cracks 41. Is in a state of entering. Many cracks 41 occur not only in the axial direction (left-right direction toward the paper surface of FIG. 7) but also in the radial direction (front-back direction toward the paper surface of FIG. 7).

  Here, the diamond-like hard carbon film that is the material of the film layer 5 will be described. A diamond-like hard carbon film (DLC film: diamond-like carbon film) is durable, has a smooth surface and excellent adhesion to a base material. The film quality is rich in denseness, and even a solution that can be permeated by a material having a structure such as graphite or polymer carbon cannot permeate and pass through the dense DLC film. Since DLC is amorphous, it does not have long-range regulation like the crystal structure of diamond. From the point of hardness, it is classified into a group of super hard materials such as diamond and sapphire. Visible light and infrared light are transmitted, it has high electrical resistance, excellent low friction and wear resistance, and is chemically inert.

  And there exists an advantage that film-forming of DLC is possible at room temperature. As a film formation method, plasma booster sputtering method (metal DLC: mixing titanium or chromium with DLC) that forms a DLC film in an inclined manner by combining sputtering and plasma CVD method is used. PBS method).

  By the way, since the film layer 40 is formed, the surface hardness of the seal lips 23a to 23c is increased and the coefficient of friction is reduced and the durability is improved. However, the seal on which the film layer 40 is formed is provided. The tips of the lips 23a to 23c become brittle. Therefore, if the inner core 20 is fitted with the film layer 40 formed, the elastic deformation of the seal lips 23a to 23c cannot be followed and a crack 41 occurs in the film layer 40 of the seal member 23. . The crack 41 may extend not only to the film layer 40 but also to the inside of the seal member 20.

  Accordingly, when the crack 41 is generated in the seal lips 23a to 23c for the first time when the fixed seal ring 18 and the rotary seal ring 19 are assembled, the viscous grease G is difficult to enter the crack 41, and as a result. The contact portion S between the seal lips 23a to 23c and the inner core metal 20 is in a rough contact state and the surface pressure increases, and the friction reduction effect of the bent film layer 40 may not be effective.

  Therefore, prior to assembly, by forming a crack 41 in the portion (contact portion S) where the film layer 40 is formed in the seal member 20, the grease G applied thereafter enters the crack 41. Since the opportunity greatly increases, when the fixed side seal ring 18 and the rotary side seal ring 19 are assembled, it is possible to make the grease G enter most of the cracks 41. As a result, the fixed-side seal ring 18 and the rotary-side seal ring 19 that have been assembled are temporarily removed, grease G is applied to the contact portion S, and then reassembled. Thus, there is an advantage that the number of assembling steps can be substantially reduced.

  That is, since the surface hardness is increased by the film layer 40 of the diamond-like hard carbon film coated on the tips of the seal lips 23a to 23c, when the inner core metal 20 is fitted and pressed, a fine crack 41 is formed. A large number of seal lip contact portions S are formed. In this case, in the state where the seal lip is cracked for the first time by fitting the seal member 23 to the inner core metal 20, the applied grease G is difficult to reach the inside of the crack 41. It takes a long time to go down.

  On the other hand, if the part in which the film layer 40 of the seal lips 23a to 23c is formed in a state in which the fine crack 41 is formed in advance as in the third embodiment of the present invention, At the time of fitting, the grease G has already entered the cracks 41 and has been smoothed. Therefore, the advantage that the surface pressure state is lowered from the time when the seal member 23 is fitted to the inner core metal 20 and assembled is obtained. Further, the membrane layer 40 also has an effect of preventing rubber swelling.

  By the way, as a method of creating the fine crack 41 in advance, the following a. ~ D. Etc. are considered. a. Passing the shaft on which the convex part having a larger diameter than the inner diameter is passed through the seal lips 23b, 23c, b. A shaft provided with a step larger than the inner diameter is passed through the seal lips 23b, 23c; c. A shaft having a taper larger than the inner diameter is passed through the seal lips 23b, 23c, d. The seal lips 23b and 23c are swirled through a shaft. In the case of the first seal lip 23a, a ring-shaped disk may be pressed.

  As described above, since a number of fine cracks 41 in the centripetal direction are formed in advance at the tip of the seal lips 23a to 23c where the film layer 40 of the diamond-like hard carbon film is formed, the fixed-side seal ring 18 And the rotation-side seal ring 19 are assembled, smoothing is possible by inserting the grease G into the cracks 41. As a result, the effect of reducing the friction coefficient by the film layer 40 can be exhibited immediately after assembly, and a bearing seal structure that can achieve both good sealing performance and long life at a high level can be realized.

  In addition, when the true spherical fine particles 30 are added to the grease G, not only the grease G but also the true spherical fine particles 30 enter the crack 41, and the smoothing of the surface is further promoted. Therefore, there is an advantage that the friction coefficient can be further reduced, and the effect of reducing the friction (rotation resistance) of the bearing and the effect of improving the sealing performance are further improved.

  In the above, the outer metal core 22 corresponds to “one member” and the inner metal core 20 corresponds to “the other member”, but in the case of a structure in which the seal member 23 is directly fitted to the outer ring 13, The outer ring 13 corresponds to “one member”. Further, in the structure in which the seal lips 23b and 23c are directly fitted to the inner ring 5, the inner ring 5 corresponds to “the other member”.

Sectional view showing wheel bearing and surrounding structure Enlarged sectional view of bearing and seal ring Enlarged sectional view of the inner seal part (Example 1) An enlarged cross-sectional view of the main part showing the state of the contact portion with the seal lip of the inner metal core Enlarged sectional view of the inner seal part (Example 2) Expanded sectional view of the inner seal part (Example 3) FIG. 6 is an enlarged sectional view showing part A of FIG. Sectional drawing of the principal part which shows the coating state of the conventional diamond-like hard carbon film

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Other member 22 One member 23 Seal member 23a-23c Seal lip 30 Spherical fine particle 40 Film layer by diamond-like hard carbon film 41 Crack-like part G Lubricating oil S Contact part

Claims (6)

A bearing seal structure in which a pair of relatively rotating members is sealed by contact between a ring-shaped seal lip of a seal member fixed to one member and a peripheral surface of the other member,
A bearing seal structure in which lubricating oil acting on a contact portion between the seal lip and the peripheral surface of the other member is provided, and the spherical oil is added to the lubricating oil. A bearing seal structure in which a pair of relatively rotating members is sealed by contact between a ring-shaped seal lip of a seal member fixed to one member and a peripheral surface of the other member,
The seal member is a bearing seal structure formed of a rubber material to which spherical fine particles are added. In claim 1,
The seal member is a bearing seal structure formed of a rubber material to which spherical fine particles are added. A bearing seal structure in which a pair of relatively rotating members is sealed by contact between a ring-shaped seal lip of a seal member fixed to one member and a peripheral surface of the other member,

A film layer made of a diamond-like hard carbon film is formed at the contact portion of the seal lip with the other member, and a fine crack-like part is formed at a portion where the film layer is formed. Seal structure for bearings. In claim 4,
A bearing seal structure in which lubricating oil acting on a contact portion between the seal lip and the peripheral surface of the other member is provided, and the spherical oil is added to the lubricating oil. In any one of Claims 1-5,
A bearing seal structure in which a film layer of a diamond-like hard carbon film is formed at a contact portion of the other member with the seal lip.

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