JP2010261598A - Sealing device and rolling bearing unit with sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently suppress a change in contact load at a sliding contact part even when the interference of an outside seal lip 22b is changed. <P>SOLUTION: A minimum wall thick part 36 having the smallest thickness is provided in the vicinity of the base end of the outside seal lip 22b. The thickness of this outside seal lip 22b increases from this minimum wall thick part 36 towards the maximum wall thick part 37 provided in the vicinity of the tip edge. The interference L<SB>1</SB>in a shaft direction on the outside face of a slinger 16 on this outside seal lip 22b is equal to or larger than 20% of a dimension in this shaft direction while this outside seal lip 22b is free. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sealing device for closing an opening end of a rolling bearing incorporated in a rotation support portion of various mechanical devices, such as a wheel bearing rolling bearing unit for supporting a vehicle (automobile) wheel on a suspension device, and the sealing device. The present invention relates to an improvement of a rolling bearing unit with a sealing device including

  Rolling bearings such as ball bearings, cylindrical roller bearings, and tapered roller bearings are incorporated in the rotation support portions of various mechanical devices. Such a rolling bearing incorporates a sealing device to prevent the grease enclosed in the inner space of the rolling bearing from leaking to the outside, and various foreign matters such as rainwater, mud, dust, etc. existing outside the rolling bearing. To prevent it from getting inside. FIG. 11 shows a structure for rotatably supporting a driving wheel of a vehicle on a suspension device as an example of a rolling bearing unit with a sealing device provided with such a sealing device.

  The rolling bearing unit with a sealing device includes an outer ring 1, a hub 2, and a plurality of rolling elements 3 and 3. Of these, the hub 2 is formed by combining a hub body 4 and an inner ring element 5. Each of the rolling elements 3, 3 includes a double row outer ring raceway 6, 6 formed on the inner peripheral surface of the outer ring 1 and a double row inner ring raceway 7, 7 formed on the outer peripheral surface of the hub 2. A plurality of them are provided so as to roll freely. In use, that is, when the wheel is rotatably supported by the vehicle suspension device, the outer ring 1 is fixed to the knuckle 8 constituting the suspension device, and the wheel is coupled to the mounting flange 9 provided on the hub body 4. Fix it. Further, a spline shaft 12 attached to the constant velocity joint 11 is engaged with a spline hole 10 provided in the central portion of the hub body 4.

  Among the rolling bearing units with a sealing device as described above, grease is sealed in the internal space 13 in which the rolling elements 3 and 3 are installed, the rolling surfaces of the rolling elements 3 and 3, The rolling contact portions between the outer ring raceways 6 and 6 and the inner ring raceways 7 and 7 are lubricated. Sealing devices 14a and 14b are provided between the inner peripheral surface of both ends of the outer ring 1 and the outer peripheral surface of the inner end of the inner ring element 5 and the outer peripheral surface of the intermediate part of the hub body 4, respectively. Both end openings of the space 13 are closed.

  Of the two sealing devices 14a and 14b, the inner end of the inner space 13 (inner with respect to the axial direction refers to the side that is in the middle in the width direction when assembled to the vehicle. The sealing device 14a that closes the opening is configured as shown in FIG. 12, for example. The sealing device 14 a is called a combination sealing device, and includes a cored bar 15, a slinger 16, and a sealing material 17. Of these, the metal core 15 corresponds to the holding member described in the claims, and is made of a metal material, and is provided with an outer diameter side cylindrical portion 18 that can be fitted and fixed to the inner peripheral surface of the end portion of the outer ring 1. The outer diameter side cylindrical portion 18 includes an outer ring portion 19 that is bent inward in the diameter direction from the outer end edge in the axial direction, and has an L-shaped cross section and has an annular shape as a whole.

  The slinger 16 includes an inner diameter side cylindrical portion 20 that can be fitted and fixed to the outer peripheral surface of the end portion of the inner ring element 5, and an inner side that is bent outward in the diameter direction from the axial inner end edge of the inner diameter side cylindrical portion 20. An annular portion 21 and an annular shape with an L-shaped cross section are provided. The sealing material 17 is made of an elastic material such as an elastomer such as rubber, and includes outer, middle and inner sealing lips 22 to 24, and the base end portion is fixedly coupled to the cored bar 15. Then, the end edge of the outer seal lip 22, which is called a side lip and is provided on the outermost diameter side so as to protrude inward in the axial direction, is entirely placed on the outer surface of the inner ring portion 21 constituting the slinger 16. The peripheral edges of the two inner and inner seal lips 23, 24 are slidably contacted with the outer peripheral surface of the inner diameter side cylindrical portion 20 constituting the slinger 16 over the entire periphery. ing. Further, grease 26 is sealed in a space 25 surrounded by the outer seal lip 22, the inner seal lip 24 and the slinger 16. In the case of such a sealing device 14a, the outer seal lip 22 corresponds to the axial seal lip described in the claims, and the intermediate and inner seal lips 23, 24 correspond to the radial seal lips described in the claims. To do.

  On the other hand, the sealing device 14b for closing the opening on the outer end side of the internal space 13 includes a cored bar 27 as a holding member and a sealing material 28 as shown in FIG. The sealing material 28 is made of an elastic material such as an elastomer such as rubber, and includes three outer, intermediate, and inner sealing lips 29 to 31, and the base end portion is coupled and fixed to the core metal 27. . Then, the tip edge of the seal lip 29, which is called the side lip and protrudes outward in the axial direction on the outermost diameter side, is slid over the entire inner surface of the base end portion of the mounting flange 9. The leading edges of the remaining two middle and inner seal lips 30 and 31 are connected to the continuous portion of the inner surface of the base end portion and the outer peripheral surface of the intermediate portion of the hub main body 4 or to the outer peripheral surface of the intermediate portion. Slid and touched. In the case of such a sealing device 14b, the outer seal lip 29 corresponds to the axial seal lip described in the claims.

  By closing the both end openings of the internal space 13 with the sealing devices 14a and 14b as described above, foreign matter such as muddy water is prevented from entering the internal space 13 and enclosed in the internal space 13. Prevents leaked grease from leaking to the outside. In the case of the conventional structure shown in FIGS. 11 to 13 described above, among the three seal lips 22 to 24 and 29 to 31 constituting the sealing devices 14a and 14b, respectively, the outermost diameter side. The outer seal lips 22 and 29 that are positioned have a substantially uniform thickness from the base end portion to the tip end portion (in the case of the sealing device 14a shown in FIG. 12), or from the base end portion toward the tip end portion. The thickness gradually decreases (in the case of the sealing device 14b shown in FIG. 13). In the case of the sealing device 14a for closing the inner end side opening of the internal space 13 shown in FIG. 12, the grease 26 is put in the space 25 surrounded by the outer seal lip 22, the inner seal lip 24 and the slinger 16. Although sealed, the grease 26 may not be sealed in the space 25 in some cases.

  In order to improve the sealing performance by the sealing devices 14a and 14b as described above, the sliding contact between the tip edges of the sealing lips 22 to 24 and 29 to 31 constituting the sealing devices 14a and 14b and the mating surface is performed. It is necessary that the state is appropriate. On the other hand, among the seal lips 22 to 24 and 29 to 31 constituting the respective sealing devices 14a and 14b, the outer seal lips 22 and 29 present on the outermost diameter side are in sliding contact with the mating surface. Based on the contact pressure of the part, the contact pressure is set to a predetermined value by bending and deforming the portion near the tip and the whole. However, such a sliding contact state between the outer seal lips 22 and 29 and the mating surface tends to be inappropriate due to a dimensional error of each part, an assembly error, and elastic deformation of each part during traveling of the vehicle.

  With respect to this point, the sealing device 14a shown in FIG. 12 that closes the inner end opening side of the internal space 13 will be described as an example. The outer seal is caused by the axial position shift between the metal core 15 and the slinger 16. There is a possibility that the sliding contact state between the tip edge of the lip 22 and the outer surface of the inner ring portion 21 of the slinger 16 may be poor. That is, when the sealing device 14a is assembled into the inner end opening of the internal space 13, the axial relative position between the cored bar 15 and the slinger 16 may be shifted to some extent due to assembly errors. In this case, the distance between the outer ring portion 19 of the core 15 and the inner ring portion 21 of the slinger 16 deviates from the design value. For example, when this distance becomes smaller than the design value, the tightening margin (elastic deformation amount) of the outer seal lip 22 is increased, and the outer edge of the outer seal lip 22 and the outer ring portion 21 are removed. The contact pressure at the sliding contact portion with the side surface increases. Since the outer seal lip 22 receives this contact pressure by curving the portion near the tip and the entire portion, when the contact pressure increases, the portion near the tip of the outer seal lip is greatly bent (becomes), The contact area of the sliding contact portion is increased. When the contact area is increased, the contact load becomes excessive, the sliding resistance (seal torque) at the sliding contact portion is increased, and the outer seal lip 22 is easily worn or loosened. It becomes difficult to ensure the durability of the sealing device 14a.

  On the other hand, when the distance is larger than the design value, the tightening margin of the outer seal lip 22 is reduced, and the sliding edge between the tip edge of the outer seal lip 22 and the outer surface of the inner ring portion 21 is reduced. The contact pressure at the contact portion is lowered. As a result, the sliding resistance is not increased due to the decrease in the contact load, but the sealing performance by the outer seal lip 22 is lowered, and it is difficult to sufficiently prevent foreign matter from entering the inner space 13. .

  Further, the improper sliding contact state between the leading edge of the outer seal lips 22 and 29 and the mating surface is also caused by elastic deformation of each part during traveling of the vehicle. That is, the central axis of the hub 2 is brought into a neutral state by elastic deformation of each component of the rolling bearing unit based on the moment applied to the hub 2 from the ground contact surface of the tire constituting the wheel through the mounting flange 9 when the vehicle turns. On the other hand, it may incline suddenly. In such a case, the sliding contact state between the leading edge of the outer seal lips 22 and 29 and the mating surface becomes non-uniform in the circumferential direction, which also reduces the durability of the outer seal lips 22 and 29 and the sealing performance. Cause the problem. This point will be described with reference to FIGS. 14 to 15 by taking the sealing device 14a on the inner end opening side of the internal space 13 as an example.

  As shown by an arrow in FIG. 14, a description will be given of a case where the moment M accompanying the turning travel is applied to the hub 2 in the clockwise direction of FIG. 14. In this case, the central axis of the hub 2 is displaced by an angle θ from the α position representing the neutral state to the β position due to elastic deformation of each part. As a result, the inner ring portion 21 of the slinger 16 that is externally fitted and fixed to the inner end portion of the inner ring element 5 constituting the hub 2 is also inclined substantially by the angle θ. In the state shown in FIG. 14, the inner ring portion 21 is displaced in the direction away from the core metal 15 as shown in FIG. As a result, the margin for tightening the outer seal lip 22 is reduced in the upper portion. Conversely, in the lower part of FIG. 14, the inner ring portion 21 is displaced in a direction approaching the core metal 15 as shown in FIG. As a result, the tightening margin of the outer seal lip 22 increases in the lower portion. On the other hand, the sealing device 14b that closes the outer end opening of the internal space 13 moves in the opposite direction to the sealing device 14a on the inner end opening side. In any case, in the portions of the sealing devices 14a and 14b where the tightening allowance of the outer seal lips 22 and 29 is reduced, the foreign matter intrusion preventing function by the outer seal lips 22 and 29 is impaired.

  In view of such circumstances, Patent Document 1 describes a structure that takes into account that changes in the tightening allowance of the seal lip are less likely to be associated with changes in the contact load of the sliding contact portion (fluctuation in sliding resistance). Yes. That is, as shown in FIG. 16, in the case of the second example of the conventional structure described in Patent Document 1, a constricted portion 32 having a reduced thickness is provided at the proximal end portion of the outer seal lip 22a. The base portion of the outer seal lip 22a has a shape in which the thickness gradually increases from the constricted portion 32 toward the tip portion. Further, an R portion 33 having an arcuate cross section is provided on the outer peripheral surface of the constricted portion 32. Further, the inner peripheral surface of the base portion of the outer seal lip 22a is provided in a portion near the base end (portion near the left end in FIG. 16), and the cylindrical portion 34 whose diameter does not change and the front half (the right half in FIG. 16). ) And a tapered surface 35 having a diameter that increases toward the tip.

  According to the sealing device of the second example of the conventional structure described in Patent Document 1 as described above, the tightening allowance of the outer seal lip 22a is caused by an assembly error or the like, or the inclination of the central axis of the hub that occurs during turning. Even when the outer surface lip 22a changes, it is possible to prevent the portion near the tip of the outer seal lip 22a from being greatly curved, and to suppress the change in the contact area at the sliding contact portion to some extent, the contact load at the sliding contact portion is reduced. There is a possibility that the change can be suppressed to some extent. For this reason, even when the tightening margin changes, the sliding resistance of the outer seal lip 22a can be suppressed to a certain extent, and the wear of the tip edge of the outer seal lip 22a can be suppressed to a certain extent. .

  However, in the case of the second example of the conventional structure described in Patent Document 1, only the restriction of the shape of the base portion of the outer seal lip 22a is considered. Regulating the shape of other parts is not considered. For this reason, when the tightening allowance of the outer seal lip 22a changes, the change in the contact area at the sliding contact portion between the tip edge and the mating surface cannot be sufficiently suppressed, and the contact load at this sliding contact portion. There is a possibility that it is not possible to sufficiently suppress changes in Then, there is a possibility that the effect of sufficiently reducing the sliding resistance of the outer seal lip 22a and sufficiently suppressing the wear of the front end edge of the outer seal lip 22a may not be obtained.

  Further, in the case of the second example of the conventional structure described in Patent Document 1, it is not considered to regulate the tightening margin between the outer seal lip 22a and the mating surface. For this reason, it is difficult to achieve a balance between reducing the contact load at the sliding contact portion and ensuring the sealing performance. That is, when the contact load at the sliding contact portion is simply reduced, it becomes difficult to ensure sufficient sealing performance. On the other hand, when this contact load is increased, it becomes easy to ensure the sealing performance. However, in this case, the sliding torque increases or the tip edge of the outer seal lip 22a is worn early. , Durability decreases.

  In the case of the second example of the conventional structure described in Patent Document 1, the outer seal lip 22a includes a continuous portion of a cylindrical portion 34 and a tapered surface 35 provided on the inner peripheral surface of the outer seal lip 22a. The distortion which arises in the vicinity of the inner peripheral surface of the base part of this becomes large. For this reason, excessive tensile stress is concentrated in the vicinity of this portion, so that the elastic material such as rubber constituting the outer seal lip 22a is liable to occur (permanent deformation) or stress relaxation. Moreover, such sag increases as the applied stress increases, that is, as the applied load increases. On the other hand, in the outer seal lip 22a, the contact load at the slidable contact portion is applied to the seal lip other than the outer seal lip 22a from the surface that needs to ensure sufficient sealing performance at the slidable contact portion. It is larger than the case of the sliding contact portion. For this reason, in the case of the outer seal lip 22a, sag and stress relaxation are more likely to occur in the elastic material than other seal lips. When the elastic material of the outer seal lip 22a is sag or stress relaxation occurs, the contact pressure at the slidable contact portion is likely to be lowered at an early stage, and it is difficult to ensure good sealing performance over a long period of time. . As a result, in the case of the structure described in Patent Document 1, there is a possibility that the initial sealing performance cannot be maintained relatively early. In particular, if the base portion of the outer seal lip 22a is bent, the followability of the outer edge of the outer seal lip 22a with respect to the mating surface decreases, so that when the mating surface is displaced away from the outer seal lip 22a, this The surface pressure of the sliding contact portion between the tip edge of the outer seal lip 22a and the mating surface is extremely likely to be lowered, and the effect of preventing foreign matter from entering by the outer seal lip 22a is extremely deteriorated.

Japanese Utility Model Publication No. 5-73364

  In the present invention, in view of the above-described circumstances, even when the tightening allowance between the axial seal lip and the mating surface changes based on an assembly error, turning of the vehicle, or the like, the contact load at the sliding contact portion is reduced. Invented to realize a structure that can sufficiently suppress changes, achieve low torque, ensure sufficient durability, and make it less likely to cause sag and stress relaxation in the axial seal lip. It is.

Among the sealing device and the rolling bearing unit with the sealing device of the present invention, the sealing device according to claim 1 is similar to the above-described conventionally known sealing device, and the outer peripheral surface of the inner ring and the outer ring rotating relative to each other. In order to close the space between the inner peripheral surface, a holding member that can be fitted and fixed to one of the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, and an elastic material, And a sealing material in which a part thereof is coupled and fixed. In addition, this sealing material is provided with an axial seal lip whose tip edge is slidably contacted with a mating surface on the side.
In particular, in the sealing device of the present invention, the axial seal lip has a minimum thickness portion having the smallest thickness in the vicinity of the proximal end portion, and the thickness increases from the minimum thickness portion toward the distal end edge. Is gradually increased, and has a shape in which the maximum thickness portion having the largest thickness exists in the vicinity of the leading edge.

  Preferably, as described in claim 2, a curved surface portion having an arcuate cross section is provided in a portion including the tip edge of the axial seal lip that is in sliding contact with the mating surface.

  More preferably, as described in claim 3, the axial seal lip and the mating surface are tightened with respect to the axial direction of the mating surface in the axial direction in the free state of the axial seal lip. 20% or more of the dimension regarding.

  More preferably, as described in claim 4, the thickness of the maximum thickness portion is set to be twice or more the thickness of the minimum thickness portion.

  More preferably, as described in claim 5, the outer peripheral surface of the base end portion of the axial seal lip has a concave shape recessed toward the inner diameter side, and the inner peripheral surface of the base end portion protrudes toward the inner diameter side. This convex shape is made to be smoothly continuous with the portion of the inner peripheral surface of the axial seal lip that is off the base end.

  More preferably, as described in claim 6, the sealing material is provided with two radial seal lips positioned axially inward of the axial seal lip. The leading edge of the radial seal lip is slidably contacted with the mating surface existing in the radial direction over the entire circumference.

Further, the rolling bearing unit with a sealing device according to claim 7 is an outer ring having an outer ring raceway on the inner peripheral surface, and an inner ring on the outer peripheral surface, similarly to the conventionally known rolling bearing unit with a sealing device. An inner ring having a track, a plurality of rolling elements provided between the outer ring track and the inner ring track, and a space existing between the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring. And a sealing device for closing the end opening.
In particular, in the rolling bearing unit with a sealing device according to the seventh aspect, the sealing device is the sealing device according to any one of the first to sixth aspects described above.
In the rolling bearing unit with a sealing device, the bearing ring that rotates when used in one of the outer ring and the inner ring is a hub for coupling and fixing the wheel during use. The other raceway ring that does not rotate during use includes a so-called hub unit that is supported by a suspension device.

According to the sealing device of the present invention configured as described above and the rolling bearing unit with a sealing device incorporating the same, even when the tightening margin between the axial seal lip and the mating surface changes, the contact at the sliding contact portion The change in load can be sufficiently suppressed, and it is easy to achieve both a reduction in torque and securing of sealing performance.
That is, the axial seal lip constituting the sealing device of the present invention has a shape in which the thickness gradually increases from the minimum thickness portion provided in the vicinity of the base end portion to the maximum thickness portion existing in the vicinity of the distal end edge. . For this reason, when the tip end edge of the axial seal lip is brought into contact with the mating surface, the above-mentioned shaft is caused by the dimensional error of each part, the assembly error, the inclination of the central axis of the hub that occurs during turning, etc. Even if the tightening allowance of the direction seal lip changes, it is possible to prevent the portion near the tip of the axial seal lip from being greatly curved, and to suppress the change in the contact area at the sliding contact portion, Changes in contact load can be sufficiently suppressed. Further, since the maximum thickness portion is provided in the vicinity of the tip edge of the axial seal lip, even if the tip edge is worn, the portion near the tip of the axial seal lip is not greatly deformed. As a result, in the case of the present invention, it is possible to easily achieve both reduction in torque and securing of sealing performance.

  The sealing device and the rolling bearing unit with the sealing device of the present invention configured and operated as described above are capable of changing the contact load at the sliding contact portion even when the tightening allowance between the axial seal lip and the mating surface changes. Can be suppressed sufficiently. In particular, even when used under severe conditions where relative inclination and eccentricity are likely to occur between two members incorporating a sealing device, such as when applied to a rolling bearing unit with a sealing device for supporting wheels of a vehicle. This is effective from the viewpoint of easily achieving low torque and ensuring durability of the rotary machine.

  Further, in the case of the sealing device according to claim 2, the change in the contact area of the sliding contact portion (torque fluctuation) with respect to the change in the contact load at the sliding contact portion between the tip edge of the axial seal lip and the mating surface. ) Can be reduced. For this reason, even when this contact load becomes large, it can suppress that a sliding torque increases or abrasion is accelerated | stimulated.

Further, in the case of the sealing device according to claim 3, the tightening margin of the axial seal lip and the mating surface in the axial direction of the mating surface is set in the axial direction in the free state of the axial seal lip. 20% or more of the dimension. For this reason, sufficient sealing performance can be secured while keeping the contact load small. Therefore, the sliding resistance of the axial seal lip can be kept small, the torque can be reduced, and sufficient durability can be ensured.
As a result, even when the tightening allowance between the axial seal lip and the mating surface changes, it is possible to suppress a change in the contact load at the sliding contact portion, and to achieve a low torque and sufficient durability. It can be secured.

  Further, according to the sealing device of the fourth aspect, even when the tightening margin between the axial seal lip and the mating surface changes, the change in the contact area at the sliding contact portion is further suppressed, and the sliding contact portion is suppressed. It is possible to further suppress the change in contact load at. For this reason, the sliding resistance of the axial seal lip can be further reduced, and the durability of the axial seal lip can be improved. Further, even when the tip end edge of the axial seal lip is worn, the tip end portion of the axial seal lip can be sufficiently secured to make it difficult to deform.

  Further, according to the sealing device of the fifth aspect, the entire base end portion of the axial seal lip can be easily elastically deformed, and excessive tensile stress is concentrated in the vicinity of the inner peripheral surface of the base end portion. Can be prevented. For this reason, it is difficult to cause sag and stress relaxation at the base end portion, and it is possible to suppress a decrease in contact surface pressure at the sliding contact portion. Therefore, good sealing performance can be maintained over a long period of time, and by reducing this contact surface pressure during assembly, sliding torque can be further reduced and durability can be improved.

The figure similar to FIG. 12 which shows the 1st example of embodiment of this invention. The figure which takes out and shows only a metal core and a sealing material from FIG. The figure similar to FIG. 12 which shows the 2nd example of embodiment of this invention. The figure which takes out and shows only a metal core and a sealing material from FIG. The result of the first experiment conducted to confirm the effect of this example is that the ratio of the axial margin of the outer seal lip to the axial dimension of the outer seal lip in the free state and the seal life of the sealing device. Diagram shown in relation. The graph which similarly shows a 2nd experimental result by the relationship between the contact load in the sliding contact part of an outer side seal lip, and a slinger, and a seal life. The diagram which similarly shows the result of a 1st simulation by the relationship between the interference of the outer seal lip, and the contact load in the said sliding contact part. The diagram which similarly shows the result of a 2nd simulation by the relationship between the fastening margin of an outer side seal lip, and the contact angle in the said sliding contact part. The diagram which similarly shows the result of a 3rd simulation by the relationship between the interference of the outside seal lip, and the contact width (dimension regarding a radial direction) in the said sliding contact part. The diagram which similarly shows a 3rd experiment result by the relationship between elapsed time and the amount of sag of an outer seal lip. Sectional drawing which shows an example of the rolling bearing unit with a sealing device used as the object of this invention. The fragmentary expanded sectional view which shows the sealing apparatus of the 1st example of the conventional structure assembled | attached to the A section of FIG. The fragmentary expanded sectional view which shows an example of the conventional structure of the sealing device assembled | attached to the B section of FIG. Sectional drawing of the rolling bearing unit with a sealing device which shows the state which a hub inclines with the moment load added at the time of driving | running | working of a vehicle. The fragmentary expanded sectional view which shows the displacement state of the slinger of the sealing device assembled | attached to the rolling bearing unit with a sealing device shown in FIG. The fragmentary expanded sectional view which shows the base of the outer side seal lip of the sealing device of the 2nd example of the conventional structure assembled | attached to the A section of FIG.

  1 and 2 show a first example of an embodiment of the present invention. The feature of this example is that the shape of the outer seal lip 22b constituting the sealing device 14a that closes the inner end opening of the inner space 13 provided with a plurality of rolling elements 3 (see FIG. 13) is devised, and the tightening margin Even if the tightening allowance between the outer seal lip 22b and the mating surface changes, the change in the contact load at the sliding contact portion is suppressed, and the torque is reduced and the durability is maintained. It is in the point of securing sufficient sex. Since the configuration and operation of the other parts are almost the same as those of the first example of the conventional structure shown in FIGS. 11 to 13 described above, the same parts are denoted by the same reference numerals, and redundant description is omitted. The characteristic part of the present invention and parts different from the above-described conventional structure will be mainly described.

By making the base end portion of the outer seal lip 22b, called a side lip, corresponding to the axial seal lip, bend from the outer peripheral surface side toward the central portion in the thickness direction, the minimum thickness portion is formed at the base end portion. 36 is provided. That is, the outer peripheral surface of the minimum thickness portion 36 has a concave shape that is recessed toward the inner diameter side. Further, the inner peripheral surface of the minimum thickness portion 36 has a convex shape protruding toward the inner diameter side. The outer seal lip 22b is formed in a shape in which the thickness gradually increases from the minimum thickness portion 36 toward the tip portion, and the thickness is maximized near the tip portion of the outer seal lip 22b. The maximum thickness portion 37 is provided. Further, in the case of this example, a taper shape in which the portion closer to the tip of the outer seal lip 22b is located on the tip side than the maximum thickness portion 37, and the portion closer to the outer diameter is removed over the entire circumference. It is said. In the present example, the thickness t ₁ of the maximum thickness portion 37 is set to be twice or more the thickness t ₂ of the minimum thickness portion 36. In the case of the illustrated example, a mountain-shaped protrusion 40 is formed over the entire circumference at a portion near the outer diameter of the distal end surface of the outer seal lip 22b. Further, the outer seal lip 22b is inclined in the direction toward the axially outer side of the rolling bearing as it goes toward the tip edge.

  The metal core 15, which is a holding member to which the sealing material 17 including the outer seal lip 22 b is coupled, has an L-shaped cross section as a whole by performing punching processing such as press processing and plastic processing on a metal plate. Is formed. The slinger 16 is also formed in an annular shape with an L-shaped cross section by punching and plastic processing such as press working on the metal plate, like the core metal 15.

  Further, in the case of this example, among the seal lips 22b, 23a, 24a constituting the seal material 17, the minimum wall thickness is minimized at the base end of the intermediate seal lip 23a located in the middle. A thick portion 38 is provided. Further, the thickness of the intermediate seal lip 23a is gradually increased from the minimum thickness portion 38 toward the maximum thickness portion 39 provided at the tip portion, and from the maximum thickness portion 39 toward the tip edge. It is small. On the other hand, among the seal lips 22b, 23a, and 24a, the inner seal lip 24a located on the innermost side gradually decreases in thickness toward the tip. The intermediate and inner seal lips 23a and 24a are also inclined in the direction toward the outer side in the axial direction of the rolling bearing as they approach the tip edge, similarly to the outer seal lip 22b.

Further, in the case of this example, the metal core 15 to which the sealing material 17 having the outer, middle and inner sealing lips 22b, 23a, 24a having the above-described shape is coupled is attached to the inner end portion of the outer ring 1. While the inner fitting is fixed by interference fitting, the slinger 16 is fixed to the inner end portion of the inner ring element 5 by outer fitting. In this state, the outer edge of the outer seal lip 22b is in sliding contact with the outer surface of the inner ring portion 21 of the slinger 16 over the entire circumference with a tightening margin. Further, in the present case, between the outer seal lip 22b and the slinger 16, the axis of the interference L ₁ in the axial direction of the axially outer side surface of the slinger 16, a free state of the outside seal lip 22b more than 20% of the dimension L ₂ with respect to the direction (preferably 25% or more) is set to. Further, the leading edges of the intermediate and inner seal lips 23a, 24a are brought into sliding contact with the outer peripheral surface of the inner diameter side cylindrical portion 20 of the slinger 16 over the entire circumference. Further, in the case of this example, a curved surface having an arc-shaped cross section having a small radius of curvature at a portion including the tip edge of the outer seal lip 22b that is in sliding contact with the outer surface of the inner ring portion 21 of the slinger 16. The part is provided over the entire circumference.

In the case of the sealing device of the present invention configured as described above and the rolling bearing unit with a sealing device incorporating the same, since the minimum thickness portion 36 is provided at the base end portion of the outer seal lip 22b, the outer seal is provided. The tip edge of the lip 22b can be efficiently copied to the outer surface of the inner ring portion 21. In the case of the present invention, even when the tightening allowance of the outer seal lip 22b changes, the change in the contact load at the sliding contact portion can be sufficiently suppressed, and the reduction in torque and the securing of sealing performance can be achieved. It is easy to achieve both.
That is, the outer seal lip 22b has a shape in which the thickness gradually increases from the minimum thickness portion 36 provided in the vicinity of the base end portion to the maximum thickness portion 37 existing in the vicinity of the distal end edge. For this reason, when the front end edge of the outer seal lip 22b is brought into contact with the mating surface, dimensional errors of each part, assembly errors, inclination of the central axis of the hub 2 (see FIG. 11) generated during turning, etc. As a result, even when the tightening margin of the outer seal lip 22b changes, it is possible to prevent the portion near the tip of the outer seal lip 22b from being greatly curved. Therefore, the contact angle α (FIG. 1) between the tip edge of the outer seal lip 22b and the outer surface of the slinger 16 can be sufficiently secured, and the change in the contact area at the sliding contact portion is suppressed, so Changes in contact load can be sufficiently suppressed. Further, since the maximum thickness portion 37 is provided in the vicinity of the tip edge of the outer seal lip 22b, even when the tip edge is worn, the rigidity of the portion near the tip of the outer seal lip 22b can be ensured. Will not be greatly deformed. As a result, it is possible to easily achieve both reduction in torque and securing of sealing performance.

In addition, in the case of this example, the tightening margin L _{1 of} the outer seal lip 22b in the axial direction of the outer surface of the slinger 16 is set to 20 of the dimension L _{2 in} the axial direction in the free state of the outer seal lip 22b. % Or more (preferably 25% or more). For this reason, sufficient sealing performance can be secured while keeping the contact load small. Accordingly, the sliding resistance of the outer seal lip 22b can be kept small, the torque can be reduced, and sufficient durability can be ensured.
As a result, even when the tightening allowance of the outer seal lip 22b changes, the change in the contact load at the sliding contact portion can be suppressed, the torque can be reduced, and the durability can be sufficiently secured.
Incidentally, with respect to the axial dimension L ₂ in the free state of the outside seal lip 22b, the upper limit of the proportion of the interference L ₁ relates to this axis direction is the from the outer peripheral edge of the outer surface of the inner circular ring portion 21 of the slinger 16 The value is in a range where the tip edge of the outer seal lip 22b does not protrude.

  In the case of this example, the portion including the tip edge of the outer seal lip 22b that is in sliding contact with the outer surface of the inner ring portion 21 of the slinger 16 has a circular arc shape with a small radius of curvature. A curved surface portion is provided over the entire circumference. For this reason, in the case of this example, the change (torque fluctuation) of the contact area of the sliding contact portion relative to the change of the contact load at the sliding contact portion can be further reduced. For example, when the tightening margin between the distal end edge of the outer seal lip 22b and the outer surface of the slinger 16 is increased, the curved surface portion of the distal end edge is elastically deformed to receive the contact pressure. Further, the elastic deformation of the curved surface portion does not greatly change the shape of the leading edge of the outer seal lip 22b that is in sliding contact with the outer surface of the slinger 16. For this reason, it is possible to further suppress an increase in the contact area of the sliding contact portion between the tip edge and the outer surface of the slinger 16, and further suppress an increase in sliding torque and acceleration of wear. I can do things.

  In addition, it is preferable that the curvature radius of the curved-surface part provided in the front-end edge of the said outer side seal lip 22b shall be 0.02-0.1 mm. On the other hand, when the radius of curvature is smaller than 0.02 mm, the outer side of the outer seal lip 22b and the outer surface of the slinger 16 are brought into contact with each other by applying a contact load. The amount of elastic deformation near the tip edge of the seal lip 22b becomes excessive. For this reason, the effect that the change of the contact width (contact area) at the sliding contact portion with respect to the variation of the contact load can be reduced cannot be obtained. Conversely, when the radius of curvature of the curved surface portion is greater than 0.1 mm, the contact width (contact area) becomes excessive, and not only the sliding torque increases, but also the sliding contact portion. , It becomes easy to bite foreign matter such as dust, and wear is promoted. Further, although the relationship between the contact load and the amount of elastic deformation slightly changes depending on the hardness of an elastic material such as rubber constituting the seal material 17, more preferably, the radius of curvature of the curved surface portion is set to 0.03 to 0. Set to 08 mm.

In the case of this example, since the thickness t ₁ of the maximum thickness portion is more than twice the thickness t ₂ of the minimum thickness portion 36, the tightening margin of the outer seal lip 22b changes. Even in this case, a change in the contact area at the sliding contact portion can be further suppressed, and a change in the contact load at the sliding contact portion can be further suppressed. For this reason, the sliding resistance of the outer seal lip 22b can be further reduced, and the durability of the outer seal lip 22b can be improved. Further, even when the tip end edge of the outer seal lip 22b is worn, the tip end portion of the outer seal lip 22b can be sufficiently secured to make it difficult to deform.

  In the case of this example, the outer peripheral surface of the base end portion of the outer seal lip 22b has a concave shape recessed toward the inner diameter side, and the inner peripheral surface of the base end portion has a convex shape protruding toward the inner diameter side. The convex shape is made to be smoothly continuous with the portion of the inner peripheral surface of the outer seal lip 22b that is off the base end. For this reason, the entire base end portion of the outer seal lip 22b can be easily elastically deformed, and excessive tensile stress can be prevented from being concentrated in the vicinity of the inner peripheral surface of the base end portion. For this reason, it is difficult to cause sag and stress relaxation at the base end portion, and it is possible to suppress a decrease in contact surface pressure at the sliding contact portion. Therefore, good sealing performance can be maintained over a long period of time, and by reducing this contact surface pressure during assembly, sliding torque can be further reduced and durability can be improved.

Next, FIGS. 3 to 4 show a second example of the embodiment of the present invention. In the case of this example, unlike the case of the first example described above, the front end surface of the outer seal lip 22c is not formed with a mountain-shaped protrusion 40 (see FIGS. 1 and 2) near the outer diameter. The cross section including the central axis of the cored bar 15 is simply linear.
Since other configurations and operations are the same as in the case of the first example described above, the same parts are denoted by the same reference numerals, and redundant description is omitted.
Note that the present invention is not limited to the shape and configuration of the outer seal lips 22b and 22c and the sealing device 14a of the above-described examples, and can be applied to, for example, the sealing device 14b shown in FIG. Of course.

  Further, the basic structure of the rolling bearing unit with a sealing device can be applied not only to the inner ring rotating structure as shown in FIG. 11 but also to the outer ring rotating structure. Furthermore, the present invention is not limited to the so-called third generation hub unit in which the inner ring raceway 7 is formed directly on the hub body 4 as shown in FIG. Furthermore, the present invention is not limited to a structure using balls as rolling elements, and can be applied to a hub unit using a roller other than balls, such as a tapered roller.

Next, the results of experiments conducted to confirm the effect of this example will be described. First, in the first experiment conducted to confirm the influence of the axial margin of the outer seal lip in this axial direction on the axial dimension of the outer seal lip in the free state on the seal life of the sealing device. I will explain. The first experiment, in the embodiment having a structure similar to that of the first example shown in FIGS. 1-2 above, the outer seal lip 22b with respect to the axial dimension L ₂ in the free state of the outside seal lip 22b A sealing device in which the ratio of the axial tightening margin L ₁ was variously used was used. And the cycle which supplies and discharges the muddy water which melt | dissolved Kanto loam powder 15% was repeated to the center axis position of this ball bearing in the state which incorporated the sealing device in the axial direction edge part of the ball bearing for every fixed time. Further, the relative rotational speed between the inner ring and the outer ring constituting the ball bearing was set to 1000 min ^−1, and the inner ring (shaft) was set to 0.3 mm TIR (total indicator reading) with respect to the outer ring. “TIR” refers to the total amount of deflection including the amount of eccentricity, the degree of inclination, and the like. In the first experiment, the seal life of each sealing device was determined under such conditions. Note that the seal life was reached when the muddy water entered the inner side of the inner seal lip 24a (the muddy water passed through the three seal lips 22b, 23a, and 24a). FIG. 5 shows the results of this first experiment. It should be noted that the seal life is practically required to be not less than the reference value (200 hours) indicated by the solid line a in FIG. As is apparent from the results of the first experiment shown in FIG. 5, according to the present invention in which the ratio of the tightening margin is 20% or more, the seal life of the sealing device can be sufficiently secured. Further, it was found that when the ratio of the tightening margin is 25% or more, the seal life can be further improved.

  Next, a description will be given of a second experiment conducted to confirm that the structure of the first example can obtain an effect that the seal life of the sealing device can be secured while keeping the contact load small. To do. In the second experiment, an embodiment in which the tightening margin between the outer seal lip 22b and the slinger 16 is the same as that in the first embodiment, and the tightening margin is the same as that of the present embodiment. The three types of sealing devices of Comparative Examples 1 and 2 deviating from the above range were used in which the contact load at the sliding contact portion between the tip edge of the outer seal lip 22b and the slinger 16 was variously changed. Of the comparative examples 1 and 2, the comparative example 1 has the same shape as the first example of the conventional structure shown in FIG. 12, and the comparative example 2 is shown in FIG. It has the same shape as the second example of the conventional structure. Further, the ratio of the maximum thickness portion 37 of the outer seal lip 22b of the embodiment to the minimum thickness portion 36 is set to 2 which is 2 or more. Further, the thickness of the outer seal lip of Comparative Example 1 is the same over the entire length (the ratio of the maximum thickness portion to the minimum thickness portion is 1), and the minimum thickness of the maximum thickness portion of the outer seal lip of Comparative Example 2 is set. The ratio to the thick part was 1.5. And in each such sealing device, the seal life was calculated | required on the same conditions as said 1st experiment. FIG. 6 shows the result of the second experiment performed in this way. It should be noted that this seal life is also required in practice to be not less than the reference value (200 hours) indicated by the solid line a in FIG.

  As is apparent from the results of the second experiment shown in FIG. 6, in the case of the above example, a sufficient seal life could be secured while keeping the contact load small. That is, in the case of the sealing device of the embodiment in which the ratio of the maximum thickness portion 37 of the outer seal lip 22b to the minimum thickness portion 36 is 2 or more, the sealing device of Comparative Example 1 in which this ratio is less than 2 is used. Even when the contact load at the sliding contact portion between the tip edge of the outer seal lip 22b and the slinger is about 40%, the required seal life can be secured. Further, in the case of the sealing device of the above example, the required seal life could be secured even when the contact load at the sliding contact portion was about 50% with respect to the sealing device of Comparative Example 2.

  Next, a simulation performed to confirm the effect obtained by setting the ratio of the maximum thickness portion and the minimum thickness portion 36 of the outer seal lip 22b to 2 or more will be described. First, in the first simulation, the outer seal lip 22b and the slinger 16 are structured using the same structure as the three types of sealing devices of the example and the comparative examples 1 and 2 used in the second experiment described above. The change in the contact load at the sliding contact portion with respect to the change in the fastening allowance was obtained. Further, there are three types of tightening allowances of the minimum, maximum, and intermediate values of the tightening allowance that varies based on the dimensional error of each part such as the seal material 17 and the assembly error. FIG. 7 shows the result of the first simulation performed in this way. Note that “min” shown on the horizontal axis in FIG. 7 represents the minimum value of the above tightening allowance, “mid” represents the intermediate value of this tightening allowance, and “max” represents the maximum value of this allowance. . In addition, the contact load indicated by the vertical axis in FIG. 7 is expressed as a relative value when the contact load at “max” of the allowance of Comparative Example 1 is 10. As is clear from the results of the first simulation shown in FIG. 7, in the case of the example, the change in the contact load at the sliding contact portion could be suppressed regardless of the change in the tightening allowance. On the other hand, in Comparative Examples 1 and 2, when the tightening allowance changed, the contact load at the sliding contact portion changed greatly.

  Next, in the second simulation, the sliding contact with respect to the change in the tightening margin of the outer seal lip 22b is performed by the structure of the three types of sealing devices of the embodiment used in the first simulation and the comparative examples 1 and 2. The change in the contact angle α between the tip edge of the outer seal lip 22b and the outer side surface of the inner ring portion 21 of the slinger 16 was determined. In addition, there are three types of tightening allowances, ie, a minimum value, a maximum value, and an intermediate value of a tightening allowance that varies based on a dimensional error of each part of the sealing material 17 and the like and an assembly error. Four types including the free state of the outer seal lip 22b). The contact angle when the tightening margin is 0 is such that the core 15 and the slinger 16 are coaxially arranged, the free end of the outer seal lip 22b, and the inner ring portion of the slinger 16 The angle formed with the outer side surface of 21. FIG. 8 shows the result of the second simulation performed in this way. The meanings represented by “min”, “mid”, and “max” indicated by the horizontal axis in FIG. 8 are the same as those in FIG. Further, the contact angle indicated by the vertical axis in FIG. 8 is expressed as a relative value when the contact angle when the tightening margin of the outer seal lip 22b is 0 is 10. As is apparent from the result of the second simulation shown in FIG. 8, in the case of the above-described embodiment, the contact between the tip edge of the outer seal lip 22b and the outer surface of the slinger 16 regardless of the change in the tightening allowance. The angle α can be secured satisfactorily.

  Next, the third simulation uses the structure of the three types of sealing devices of the embodiment used in the first and second simulations and Comparative Examples 1 and 2 to change the tightening allowance of the outer seal lip 22b. The change in the radial dimension (contact width) of the sliding contact portion was determined. In addition, as in the case of the first simulation described above, the tightening allowance is the difference between the minimum value, maximum value, and intermediate value of the tightening allowance that varies based on the dimensional error of each part of the sealing material 17 and the like and the assembly error. There were three types. FIG. 9 shows the result of the third simulation performed in this way. The meanings represented by “min”, “mid”, and “max” indicated by the horizontal axis in FIG. 9 are the same as those in FIGS. Further, the contact width indicated by the vertical axis in FIG. 9 is expressed as a relative value when the contact width is 10 when the tightening margin of the outer seal lip 22b of Comparative Example 1 is “max”. As is apparent from the result of the third simulation shown in FIG. 9, in the case of the above-described embodiment, the contact between the leading edge of the outer seal lip 22b and the outer surface of the slinger 16 regardless of the change in the tightening allowance. The increase in the area of the part could be suppressed.

  Next, in order to confirm that the structure of the first example shown in FIGS. 1 and 2 described above can obtain the effect that the outer seal lip 22b can be prevented from sagging even after a long period of time. The third experiment will be explained. In the third experiment, three types, the example used in the first experiment and the first and second comparative examples, were used. Further, in these examples and comparative examples 1 and 2, the axial tightening margin between the leading edge of the outer seal lip 22b and the slinger 16 varies based on the dimensional error of each part such as the seal material 17 and the assembly error. The intermediate value (mid) of the tightening allowance. And after leaving such an Example and Comparative Examples 1 and 2 in a thermostat bath at a temperature of 60 ° C., they are taken out every certain time, and the axial dimension in the free state of the outer seal lip 22b. The change in (height) was determined as a sag amount. FIG. 10 shows the result of the third experiment performed in this manner. The amount of sag shown by the vertical axis in FIG. 10 is expressed as a relative value when the amount of sag in Comparative Example 2 at the end of the experiment is 10.

  As is apparent from the results of the third experiment shown in FIG. 10, in the case of the above embodiment, it is possible to suppress excessive stress from being concentrated on a part of the outer seal lip 22b, and even after a long period of time has elapsed. The amount of sag of the outer seal lip 22b can be reduced.

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Hub 3 Rolling element 4 Hub body 5 Inner ring element 6 Outer ring raceway 7 Inner ring raceway 8 Knuckle 9 Mounting flange 10 Spline hole 11 Constant velocity joint 12 Spline shaft 13 Internal space 14a, 14b Sealing device 15 Core metal 16 Slinger 17 Sealing material 18 Outer diameter side cylindrical portion 19 Outer ring portion 20 Inner diameter side cylindrical portion 21 Inner ring portion 22, 22a, 22b, 22c Outer seal lip 23, 23a Intermediate seal lip 24, 24a Inner seal lip 25 Space 26 Grease 27 Core 28 Seal material 29 Outer seal lip 30 Intermediate seal lip 31 Inner seal lip 32 Constricted part 33 R part 34 Cylindrical part 35 Tapered surface 36 Minimum wall thickness 37 Maximum wall thickness 38 Minimum wall thickness 39 Maximum wall thickness 40 Projection

Claims (7)

  In order to close the space between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring that rotate relative to each other, a holding member that can be fitted and fixed to one peripheral surface of the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, A shaft that is made of an elastic material and includes a sealing material in which a part of the holding member is fixedly coupled to the holding member. In the sealing device provided with the directional seal lip, the axial seal lip has a minimum thickness portion having the smallest thickness in the vicinity of the proximal end portion, and is directed from the minimum thickness portion toward the distal end edge. The sealing device is characterized by having a shape in which the thickness gradually increases and the maximum thickness portion having the largest thickness exists in the vicinity of the leading edge.   The sealing device according to claim 1, wherein a curved surface portion having an arcuate cross section is provided at a portion including a tip edge of the axial seal lip that is in sliding contact with the mating surface.   The margin of tightening between the axial seal lip and the mating surface in the axial direction of the mating surface is 20% or more of the dimension in the axial direction of the axial seal lip in the free state. The sealing device described in 1.   The sealing device according to any one of claims 1 to 3, wherein the maximum thickness portion is twice or more the thickness of the minimum thickness portion.   The outer peripheral surface of the base end portion of the axial seal lip has a concave shape that is recessed toward the inner diameter side, the inner peripheral surface of the base end portion has a convex shape that protrudes toward the inner diameter side, and this convex shape is the axial seal lip. The sealing device according to any one of claims 1 to 4, wherein the sealing device is smoothly continuous with a portion of the inner peripheral surface of the inner surface that is off the base end.   The sealing material is provided with two radial seal lips positioned axially inward of the axial seal lip, and the distal end edge of each radial seal lip is entirely placed on the mating surface existing in the radial direction. The sealing device according to any one of claims 1 to 5, wherein the sealing device is in sliding contact with the periphery.   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, and an inner circumference of the outer ring. In a rolling bearing unit with a sealing device provided with a sealing device for closing an end opening of a space existing between a surface and the outer peripheral surface of the inner ring, the sealing device is any one of claims 1 to 6. A rolling bearing unit with a sealing device, characterized in that the sealing device is described.

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