JP2006125465A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a longer life wheel rolling bearing which has good sealing performance even in bad environment and to which lubricant is stably supplied. <P>SOLUTION: The rolling bearing comprises an outer ring equivalent member 2 having outer ring raceways 8, 8 on the inner peripheral face, an inner ring equivalent member 3 having inner ring raceways 9, 9 on the outer peripheral face, a plurality of rolling elements 10 rollingly provided between each of the outer ring raceways 8, 8 and each of the inner ring raceways 9, 9, and sealing devices 12a, 12b for blocking an axial opening portion between the inner peripheral face of the outer ring equivalent member 2 and the outer peripheral face of the inner ring equivalent member 3. The sealing devices 12a, 12b have seal lips 114-116, 218-220 and counter materials 106, 4 with which the seal lips have slide contact, respectively. Dynamic pressure grooves 300 are provided in slide contact portions 302 of the seal lips with the counter materials. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling bearing used, for example, to rotatably support a wheel of an automobile, and more specifically to prevent intrusion of dust, water, water vapor, muddy water, and the like from the outside into the bearing. The present invention relates to a rolling bearing provided with a sealing device.

For example, a rolling bearing for a wheel that supports a wheel of an automobile or a railway vehicle is usually used outdoors while being exposed to rainwater, wind and snow, dust, or the like. In extreme cases, it may be used while immersed in water. For this reason, as this type of bearing, a bearing provided with a sealing device having an elastic seal is known as a measure against water resistance (see, for example, Patent Document 1). In this sealing device, a seal lip of an elastic member is slidably contacted with a seal plate fitted to an outer ring to seal between the inner ring and the outer ring.
JP 2001-165179 A

  The above-described sealing device exhibits sufficient sealing performance in a relatively clean environment with little water splashing and little dust. However, as is well known, rolling bearings for wheels are used outdoors, sometimes exposed to rainwater, wind and snow, and dust, and sometimes used in situations where they are immersed in seawater. However, in the above-described sealing device in which the sliding surface of the seal lip is merely brought into sliding contact with the sealing plate, sufficient sealing performance may not be obtained in such a poor situation.

  On the other hand, rolling bearings for wheels are required to have a low torque in order to improve the fuel efficiency of automobiles, and seal lips are often used with a low tightening force in sealing devices. For this reason, in the above-mentioned poor environment, particularly when immersed in muddy water, water pressure is also applied, so that the sealing performance of the sealing device cannot be maintained, and dust or the like enters the rolling bearing together with water. May cause poor lubrication. As described above, the above-described sealing device cannot be said to have sufficient sealing performance in the above severe use environment.

  Accordingly, an object of the present invention is to provide a long-life rolling bearing that has a good sealing property even in such a poor environment, and further has a lubricant supplied stably.

  In order to achieve the above object, a rolling bearing according to the present invention is freely rollable between an outer ring having an outer ring raceway on an inner peripheral surface, an inner ring having an inner ring raceway on an outer peripheral surface, and the outer ring raceway and the inner ring raceway. A plurality of rolling elements provided on the outer ring, and a seal device that closes an axial opening between the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring, and the seal device includes a seal lip and the seal It has a mating material with which the lip is slidably contacted, and a dynamic pressure groove is provided on a sliding surface of the seal lip with the mating material.

  And it is preferable that the said dynamic-pressure groove | channel consists of a several groove part arranged along the sliding direction of the said seal lip with respect to the said counterpart material.

  According to the rolling bearing of the present invention, by providing a dynamic pressure groove on the sliding contact surface with the mating member of the seal lip constituting the seal device, it is excellent even when used in a harsh environment such as being immersed in muddy water. Sealing performance, and desired performance can be maintained over a long period of time.

Hereinafter, the rolling bearing for wheels concerning the embodiment of the present invention is explained with reference to drawings.
FIG. 1 is a sectional view showing the structure of a rolling bearing for a wheel which is an embodiment according to the present invention. FIG. 2 is an enlarged view of a portion surrounded by a dotted circle II in FIG. 3 is an enlarged view of a portion surrounded by a dotted circle III in FIG. 1, a cross-sectional view of the sealing device, and FIG. 4 is a plan view showing a dynamic pressure groove formed on the sliding surface of the seal lip.

  In the present invention, the structure of the wheel rolling bearing itself is not limited. For example, a rolling bearing including seal devices 12a and 12b as shown in FIG. 1 can be exemplified. The structures of the sealing devices 12a and 12b are not limited, and examples thereof include an elastic member provided with a sealing lip as shown in FIGS.

  As shown in FIG. 1, in the rolling bearing 1, the outer ring equivalent member 2 that is a fixed ring is supported and fixed to a suspension device (not shown) by an attachment portion 14 formed on the outer peripheral surface thereof. Therefore, the outer ring equivalent member 2 does not rotate during use.

  Inside the outer ring equivalent member 2, an inner ring equivalent member 3 which is a rotating wheel is provided concentrically with the outer ring equivalent member 2, and the inner ring equivalent member 3 rotates during use. The inner ring equivalent member 3 includes a hub 4 and an inner ring 5. Of these, the hub 4 has a spline groove 6 formed on the inner peripheral surface thereof, and the outer peripheral surface of the outer end portion (the left end in FIG. 1) on the outer side in the axial direction (the outer side in the vehicle width direction when assembled to the vehicle). The mounting flange 7 is formed in the. When assembled to the vehicle, a drive shaft that is rotationally driven through a constant velocity joint is inserted into the spline groove 6, and a wheel is fixed to the mounting flange 7.

  Double row outer ring raceways 8, 8 are formed on the inner peripheral surface of the outer ring equivalent member 2, and the inner ring raceways 9, 9 are respectively formed on the outer circumferential surface of the hub 4 in the axial intermediate portion and the outer circumferential surface of the inner ring 5. Is formed. Further, rolling elements 10 and 10 are provided between the outer ring raceways 8 and 8 and the inner ring raceways 9 and 9 so that the inner ring equivalent member 3 is rotatable with respect to the outer ring equivalent member 2. Moreover, in order to hold | maintain the rolling elements 10 and 10 so that rolling is possible, the holder | retainers 11 and 11 are provided. In the illustrated example, balls are used as the rolling elements 10 and 10, but in the case of a heavy vehicle hub unit, tapered rollers may be used as the rolling elements.

  Further, a seal device 12a is provided between the inner end 5 (the right end in FIG. 1) on the inner side in the axial direction of the outer ring equivalent member 2 (the inner side in the vehicle width when assembled to the vehicle) and the inner ring 5, and the outer ring equivalent. A seal device 12b is provided between the outer end portion of the member 2 and the outer peripheral surface of the intermediate portion in the axial direction of the hub 4, and the inner peripheral surface and the inner ring equivalent member of the outer ring equivalent member 2 are provided by these seal devices 12a and 12b. 3, the openings on both sides in the axial direction of the space 13 in which the rolling elements 10, 10 between the outer peripheral surfaces are installed are closed.

  As shown in FIG. 2, the sealing device 12 a includes a cored bar 105, a slinger 106, and an elastic member 107. Of these, the cored bar 105 is integrally formed by subjecting a metal plate such as a low carbon steel plate to punching processing such as press processing and plastic processing. Such a metal core 105 includes an outer diameter side cylindrical portion 109 fitted and fixed to the inner peripheral surface of the inner end portion of the outer ring corresponding member 2 constituting the rolling bearing 1, and the axial direction of the outer diameter side cylindrical portion 109 The inner ring portion 110 is bent inward in the diametrical direction from the outer end green (the left end edge in FIG. 2), and is formed in an annular shape with a substantially L-shaped cross section.

  In addition, the slinger 106 is integrally formed by subjecting a metal plate having excellent corrosion resistance, such as a stainless steel plate, to punching processing such as press processing and plastic processing. This type of slinger 106 includes an inner diameter side cylindrical portion 112 fitted and fixed to the outer peripheral surface of the inner ring 5 constituting the rolling bearing 1, and an axially inner end edge of the inner diameter side cylindrical portion 112 (the right end edge in FIG. 2). ) And an outer ring portion 113 bent outward in the diameter direction, and formed in an annular shape with an L-shaped cross section.

  The elastic member 107 is formed of an elastic material in an annular shape, and includes three seal lips 114, 115, and 116 on the outer side, the middle, and the inner side in the diametrical direction. Has been. Then, the distal end edge of the outer seal lip 114 positioned on the outermost side in the diametrical direction is brought into sliding contact with the axially outer side surface (left side surface in FIG. 2) of the outer ring portion 113 constituting the slinger 106, and the remaining two The leading edges of the intermediate seal lip 115 and the inner seal lip 116 that are the seal lips are slidably contacted with the outer peripheral surface of the inner diameter side cylindrical portion 112 constituting the slinger 106. As a result, leakage of the encapsulated grease is prevented and intrusion of dust, water, muddy water, and the like from the outside into the bearing is prevented.

  The three seal lips 114, 115, 116 slide relative to the slinger 106 rotating together with the inner ring equivalent member 3 in the direction opposite to the rotation direction of the slinger 106.

  As shown in FIG. 3, the sealing device 12 b includes a cored bar 216 and an elastic member 217 each formed in an annular shape. Of these, the cored bar 216 is integrally formed by subjecting a metal plate such as a low carbon steel plate to punching processing such as press processing and plastic processing, and is fitted and fixed to the inner peripheral surface of the outer end portion of the outer ring equivalent member 2. ing. The elastic member 217 is made of an elastic material, is insert-molded on the cored bar 216, and is joined by bonding or the like.

  The metal core 216 includes an outer diameter side cylindrical portion 222 that is fitted and fixed to the inner peripheral surface of the outer end portion of the outer ring equivalent member 2 that constitutes the rolling bearing 1, and an inclined portion 227 that is continuous from the outer diameter side cylindrical portion 222. And a support plate portion 223 that is bent inward in the diametrical direction from an axially outer end edge (left end edge in FIG. 3) of the outer diameter side cylindrical portion 222.

  The outer diameter of the outer diameter side cylindrical portion 222 in the free state is set slightly larger than the inner diameter of the outer end portion of the outer ring equivalent member 2 into which the outer diameter side cylindrical portion 222 is fitted. The cylindrical portion 222 can be fitted and fixed to the outer end portion of the outer ring equivalent member 2 by an interference fit. Moreover, the support plate part 223 has a substantially S-shaped cross-sectional shape, and is inclined in a direction approaching the rolling element 10 installed in the space 13 (rightward in FIG. 3) as it goes inward in the diameter direction. .

  The elastic member 217 is insert-molded on the cored bar 216 and joined by bonding or the like. The outer diameter in the free state of the outer peripheral edge of the elastic member 217 covering the outer peripheral surface of the inclined portion 227 is set slightly larger than the inner diameter of the outer end portion of the outer ring equivalent member 2, and the outer diameter side cylindrical portion 222. Is fitted and fixed to the outer end portion of the outer ring equivalent member 2, and is elastically pressed between the outer peripheral surface of the inclined portion 227 and the inner peripheral surface of the outer end portion of the outer ring equivalent member 2, and Ensure sealing performance.

  The elastic member 217 includes two outer-diameter side and inner-diameter side seal lips 218 and 219, and one radial seal lip 220. Then, the two side seal lips 218 and 219 are slidably contacted with the axially inner side surface (the right side surface in FIG. 3) of the mounting flange 7 of the hub 4, and the radial seal lip 220 is axially intermediate outer peripheral surface of the hub 4 In sliding contact. The two side seal lips 218 and 219 are inclined toward the outer side in the diametrical direction toward the tip edge, thereby ensuring the function of preventing entry of foreign matter into the space 13. In addition, the radial seal lip 220 is inclined in the direction toward the inner side of the space 13 (right side in FIG. 3) toward the leading edge, thereby ensuring the grease leakage prevention function.

  The three seal lips 218, 219, and 220 constitute the inner ring equivalent member 3 and slide relative to the hub 4 in a direction opposite to the rotation direction of the hub 4. It becomes.

  In the wheel rolling bearing having the above-described structure, in this embodiment, the mating member of the seal lips 114 to 116 and 218 to 220 constituting the seal devices 12a and 12b (that is, the seal lips 114 to 116 is the slinger 106, The seal lips 218 to 220 are the hub 4), and a dynamic pressure groove is provided on the sliding contact surface.

  The sliding surface of the seal lip provided with the dynamic pressure groove is a sliding surface indicated by reference signs A to F in FIGS. 2 and 3. If these sliding surfaces A to F are used, the dynamic pressure groove is arbitrarily set. can do. And it is preferable to apply | coat grease or lubricating oil to the sliding contact surface of a seal lip.

  An example of the dynamic pressure groove is a shape shown in FIG. The dynamic pressure groove 300 is formed by arranging a plurality of groove portions 301 recessed in a triangular shape in plan view along a sliding direction of the seal lip with respect to the mating member. Each groove portion 301 has one corner portion disposed in the center in the width direction of the slidable contact surface 302 (that is, the direction perpendicular to the circumferential direction of the slidable contact surface 302, and the circumferential direction coincides with the sliding direction). The opposite side facing the corner is arranged in parallel to the width direction of the sliding contact surface 302 (that is, so as to be orthogonal to the circumferential direction of the sliding contact surface 302). It is formed in an isosceles triangle shape that is line-symmetric with respect to a circumference passing through the center in the width direction of the surface 302.

  The angle a of the corner portion disposed at the center in the width direction of the sliding contact surface 302 in each groove portion 301 is preferably 10 ° to 170 °, more preferably 30 ° to 100 °. Within this range, an oil film is likely to be formed on the sliding contact surface 302, and the oil film is likely to be retained. As a result, the bearing life provided with the sealing devices 12a and 12b can be improved.

  As the length dimension b of the opposite side of each groove portion 301, the ratio of the sliding contact surface 302 to the width is 1% to 90%, more preferably 10% to 70%. Within this range, an oil film is likely to be formed on the sliding contact surface 302, and the oil film is likely to be retained. As a result, the bearing life provided with the sealing devices 12a and 12b can be improved.

  The depth c of each groove 301 is 1 μm or more, more preferably 1 μm or more and 500 μm or less. Within this range, an oil film is likely to be formed on the sliding contact surface 302, and the oil film is likely to be retained. As a result, the bearing life provided with the sealing devices 12a and 12b can be improved.

  Then, as in the embodiment, by providing the dynamic pressure groove 300 on the sliding contact surface 302 with the mating member of the seal lip, an oil film is formed between the tip of the seal lip and the mating material. In addition to preventing intrusion, the seal lip can be prevented from being worn, and a stable low torque can be provided.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples. In addition, this invention is not restrict | limited at all by these Examples.
The dynamic pressure grooves used in the HUB seal unit used in the examples are as follows.
[Dynamic pressure groove shape]
Angle a: 80 °
Length b: 70% (ratio to the width of the sliding contact surface)
Depth c: 80 μm
[Use lip tip]
Dynamic pressure grooves are formed on the sliding surfaces A, B, D, E, and F of the seal lip with the mating material (see FIGS. 2 and 3).

  The bearing provided with the sealing device having the dynamic pressure groove was used as an example, the bearing provided with the sealing device without the dynamic pressure groove was used as a comparative example, and immersed in muddy water using a rotation tester manufactured by NSK Ltd. Assuming the case, a sealing test was conducted.

In the test, the sealability was evaluated after rotating continuously for 100 hours. The test condition criteria are as follows.
Rotation speed: 1000rpm
Rotation time: 100 hours Shaft eccentricity: 0.5mm TIR
Mud composition: 20% JIS class 8 dust (immersion to the shaft center)
Grease: Urea soap, mineral oil

  As a criterion for determining the sealing performance, the evaluation was made based on the amount of water contained in the grease applied to the hub unit bearing. A case where the water content was 1% or less was marked as “good”, a case where the water content was 2-5% was marked as “good” and a “△” was marked, and the water content exceeded 5%. Cases were marked as "x" for failure.

The above results are as follows.
Example: ○
Comparative example: ×

  From the above, the examples showed better results than the comparative examples. That is, it has been found that a rolling bearing characterized in that a dynamic pressure groove is provided on a sliding contact surface with a mating member of a seal lip constituting the seal device has an excellent sealing performance.

It is sectional drawing which shows the structure of the rolling bearing for wheels which is one Embodiment which concerns on this invention. FIG. 2 is an enlarged view of a portion surrounded by a dotted circle II in FIG. 1 and a cross-sectional view of the sealing device. FIG. 3 is an enlarged view of a portion surrounded by a dotted circle III in FIG. 1 and a cross-sectional view of the sealing device. It is a top view which shows the dynamic pressure groove formed in the sliding contact surface of a seal lip.

Explanation of symbols

1 Rolling bearing for wheel 2 Outer ring equivalent member (outer ring)
3 Inner ring equivalent member (inner ring)
4 Hub 5 Inner ring 8 Outer ring raceway 9 Inner ring raceway 10 Rolling elements 12a, 12b Sealing device 13 Space 114, 115, 116 Seal lip 218, 219 Side seal lip (seal lip)
220 Radial seal lip (seal lip)
300 Dynamic pressure groove 301 Groove part 302 Sliding surface

Claims (2)

An outer ring having an outer ring raceway on the inner peripheral surface;
An inner ring having an inner ring raceway on the outer peripheral surface;
A plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to be freely rollable;
A sealing device for closing an axial opening between an inner peripheral surface of the outer ring and an outer peripheral surface of the inner ring;
With
The seal device has a seal lip and a mating material with which the seal lip is in sliding contact,
A rolling bearing characterized in that a dynamic pressure groove is provided on a sliding contact surface of the seal lip with the mating member.   The rolling bearing according to claim 1, wherein the dynamic pressure groove includes a plurality of groove portions arranged along a sliding direction of the seal lip with respect to the counterpart material.

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