JP4483220B2 - Rolling bearing unit for wheel support with seal ring - Google Patents

Description

The present invention relates to an improvement in a seal ring for closing an opening end of a wheel bearing rolling bearing unit for supporting a vehicle (automobile) wheel on a suspension device.

Rolling bearings such as ball bearings and tapered roller bearings are incorporated in a rotation support portion for supporting vehicle wheels on a suspension device . 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. 9 shows an example of a wheel bearing rolling bearing unit with a seal ring, which is a kind of such a sealing device, and a driven wheel of a vehicle (rear wheel of FF vehicle, FR vehicle, RR vehicle). A structure for rotatably supporting a front wheel on a suspension device is shown.

The wheel support rolling bearing unit with a seal ring is provided on the outside of the hub 2 constituting the inner ring equivalent member together with the inner ring element 1 described below (the outside in the axial direction is the outer side in the width direction when assembled to the vehicle. 1 to 3 and 9 to 11. On the other hand, the inner side in the axial direction refers to the side closer to the center in the width direction, and the right side of FIGS. The same applies to the whole.) An outward flange 3 for connecting and fixing the wheel is formed on the outer peripheral surface of the end portion. Further, an inner ring raceway 4 a and a stepped portion 5 are formed on the outer peripheral surface of the intermediate portion of the hub 2. An inner ring element 1 having an inner ring raceway 4b formed on the outer circumferential surface thereof is externally supported on the outer circumferential surface of the hub 2 near the inner end with the outer end surface abutted against the stepped portion 5. .

A male screw portion 6 is formed at the inner end portion of the hub 2. The inner ring element 1 is fixed to a predetermined portion of the outer peripheral surface of the hub 2 by screwing a nut 7 into the male screw portion 6 and further tightening. On the outer peripheral surface of the intermediate portion of the outer ring 8 arranged around the hub 2, there is provided an outward flange-shaped mounting portion 9 for fixing the outer ring 8 to the suspension device. Further, outer ring raceways 10a and 10b are formed on the inner peripheral surface of the outer ring 8 so as to face the inner ring raceways 4a and 4b, respectively. A plurality of rolling elements 11 and 11 are provided between the inner ring raceways 4a and 4b and the outer ring raceways 10a and 10b, respectively, so that the hub 2 can freely rotate inside the outer ring 8. Yes. Each of the rolling elements 11 and 11 is held by the cages 12 and 12 so as to roll freely for each row.

  A seal ring 13 is mounted between the inner peripheral surface of the outer end portion of the outer ring 8 and the outer peripheral surface of the hub 2. And by this seal ring 13, it exists between the inner peripheral surface of the outer ring | wheel 8, and the outer peripheral surface of the said hub 2 and the inner ring | wheel element 1, and the outer end of the internal space 14 which provided the said some rolling elements 11 and 11 The opening is blocked. In addition, by covering the inner end opening of the outer ring 8 with a cover 15, foreign matter such as dust and rainwater can be prevented from entering the inner space 14 from the inner end opening and the grease filled in the inner space 14 can be prevented. To prevent leakage to the outside.

  In order to sufficiently prevent foreign matter from entering the internal space 14 and to prevent leakage of grease filled in the internal space 14, it is necessary to ensure the sealing performance of the seal ring 13. As a seal ring of the first example of the conventional structure considered for such a purpose, Patent Document 1 describes a seal ring 13 having a shape as shown in FIG. The seal ring 13 includes a cored bar 16 and a sealing material 17 each formed in a ring shape. Of these, the core 16 is made of a metal plate and is fitted and fixed to the outer end of the outer ring 8. The sealing material 17 is made of an elastic material such as an elastomer such as rubber, and is bonded and fixed to the core metal 16 by baking or the like. The sealing material 17 includes an outer diameter side, an inner diameter side, two side seal lips 18 and 19, and a radial seal lip 20. Then, these two side seal lips 18 and 19 are inclined in a direction toward the outer side in the diameter direction toward the leading edge. Further, the radial seal lip 20 is inclined inward in the axial direction toward the tip edge. The leading edge of each of the outer diameter side and inner diameter side side seal lips 18, 19 is slidably contacted with the inner surface of the outward flange 3 provided on the hub 2, and the distal edge of the radial seal lip 20 is moved to the hub. 2 is in sliding contact with the outer peripheral surface of the intermediate portion. Also, the thicknesses of the outer side and inner side side seal lips 18 and 19 and the radial seal lip 20 are substantially the same over the entire length. Also, the outer diameter side and inner diameter side side seal lips 18 and 19 are formed in the same shape.

In the case of the wheel bearing rolling bearing unit with seal ring shown in FIG. 9, the inner end opening of the inner space 14 is closed by the cover 15, and this inner end opening is closed to an annular seal. It may be blocked by a ring.

  In the case of the seal ring 13 of the first example of the conventional structure shown in FIG. 10 described above, there are the following problems. That is, in the case of the seal ring 13 of the first example, both the outer diameter side and inner diameter side side seal lips 18, 19 are formed in the same shape, and the thickness of each side seal lip 18, 19 is They are almost the same over the entire length. In the case of such a seal ring 13, the side seal lips 18 and 19 as a whole are greatly curved and deformed to act on the contact portion between the tip edge of each side seal lip 18 and 19 and the mating surface. Subject to contact pressure.

Further, if it is intended to ensure sufficient sealing performance by the seal ring 13, the torque (sliding torque) required to rotate the hub 2 increases. And based on this torque increase, the fuel consumption performance and motion performance of the motor vehicle incorporating the wheel bearing rolling bearing unit with seal ring deteriorate. That is, in order to ensure the sealing performance, the rigidity of the side seal lips 18 and 19, particularly the rigidity of the outer diameter side seal lip 18 that is directly exposed to foreign matter, is improved. It is necessary to increase the contact pressure (contact load) between the tip edge of the lip 18 and the side surface of the outward flange 3 or to increase the tightening margin of the outer diameter side seal lip 18 . On the other hand, in the case of the seal ring 13 of the first example of the conventional structure shown in FIG. 10, the outer diameter side and inner diameter side side seal lips 18 and 19 are formed in the same shape. When the contact pressure between the tip edge of the outer diameter side side seal lip 18 and the side surface of the outward flange 3 is increased, the contact pressure between the side surface and the inner diameter side side seal lip 19 also increases, and the torque increases. Becomes excessive.

  Further, when the tightening allowance of the outer diameter side seal lip 18 is increased in order to ensure the sealing performance, the outer diameter side seal lip 18 as a whole becomes larger. The shape of the contact portion of the tip edge of 18 greatly changes. For this reason, the contact area between the tip edge and the side surface of the outward flange 3 increases, and the sliding torque increases. On the other hand, when the tightening margin is reduced, the contact area is reduced and the sliding torque is reduced. However, it is difficult to ensure sufficient sealing performance, and the life is shortened. Thus, in the case of the first example of the conventional structure, it is difficult to reduce the torque while ensuring sufficient sealing performance.

  In view of such circumstances, Patent Document 2 describes a seal ring 13a that has been considered for the purpose of reducing torque while ensuring sufficient sealing performance, as shown in FIG. In the case of the seal ring 13a of the second example of the conventional structure described in Patent Document 2, the thickness of the inner diameter side side seal lip 19a is made smaller than the thickness of the outer diameter side seal lip 18. . Therefore, in the case of the seal ring 13a of the second example of the conventional structure, the sliding torque can be made smaller than that of the seal ring 13 of the first example of the conventional structure shown in FIG. However, in the case of the second example of the conventional structure, as in the case of the first example of the conventional structure described above, the thicknesses of the side seal lips 18 and 19a are substantially the same over the entire length. For this reason, when the tightening margin of each of the side seal lips 18 and 19a is increased in order to further improve the sealing performance, the shape of the contact portion of the tip edge of each of the side seal lips 18 and 19a changes greatly. As a result, the contact area between the leading edge and the side surface of the outward flange increases, and the sliding torque may increase. For this reason, in the case of the second example of the conventional structure, there is still room for improvement in achieving low torque while ensuring sufficient sealing performance.

In particular, in the case of a rolling bearing unit for supporting a wheel of an automobile incorporating the seal rings 13 and 13a as described above, the sliding between the outer side and inner side side seal lips 18, 19, and 19a and the mating surface. The contact state tends to be inappropriate due to elastic deformation of each part during traveling of the vehicle. That is, in the case of a rolling bearing unit with a seal ring for supporting a wheel of an automobile, the rolling bearing unit is based on the moment applied to the hub 2 from the ground contact surface of the tire constituting the wheel through the outward flange 3 when the vehicle is turning. Due to the elastic deformation of the constituent members, the central axis of the hub 2 may be rapidly inclined with respect to the neutral state, or the central axis may be deviated (eccentric) from the neutral state. In such a case, the sliding contact state between the leading edge of each of the side seal lips 18, 19, 19a and the mating surface may be non-uniform in the circumferential direction. For example, when the central axis of the hub 2 is abruptly inclined with respect to the neutral state, each of the side seals is provided at a part of the circumferential direction of the sliding contact portion between the side seal lips 18, 19, 19a and the mating surface. The tightening allowance of the lips 18, 19, 19a is reduced, and the tightening allowance is increased at a portion radially opposite to this part. In addition, when the central axis is eccentric, only a part in the circumferential direction of the tip edge of each side seal lip 18, 19, 19a is a cylindrical surface provided on the side surface of the outward flange 3 and the outer peripheral surface of the hub 2. There is a possibility that the tightening margin increases in part in the circumferential direction in sliding contact with the curved surface portion which is a continuous portion. As described above, the sliding contact state becomes non-uniform in the circumferential direction, so that problems such as an increase in sliding torque and a decrease in sealing performance of the side seal lips 18, 19, 19a are likely to occur.

Japanese Utility Model Publication No. 7-34224 JP-A-9-287619

In consideration of the above-described circumstances, the rolling bearing unit with a wheel support with a seal ring according to the present invention is based on an assembly error, turning of a vehicle, etc. Even if the cost changes, the change in contact load at the sliding contact portion can be sufficiently suppressed, and a structure that can achieve both high sealing performance and low torque can be achieved. Invented accordingly.

Sealing ring with wheel support rolling bearing unit of the present invention, like the seal ring with the wheel supporting rolling bearing unit known in the prior art described above, has outer ring raceway of the double row inner circumferential surface, in use Equivalent to an inner ring having a non-rotating outer ring, a double-row inner ring raceway at a portion of the outer peripheral surface facing each outer ring raceway, and an outer flange at the portion protruding from the one end opening of the outer ring at the remaining outer peripheral surface A member, a plurality of rolling elements provided between each of the outer ring raceways and the inner ring raceways, and a seal for closing an annular gap between one end opening of the outer ring and the inner ring equivalent member With a ring.
Also, this seal ring is made of a sealing material made entirely of an annular shape by an elastic material in order to close the space between the outer peripheral surface of the inner ring equivalent member rotating on the inner diameter side of the outer ring and the inner peripheral surface of the outer ring. This seal material has an outer-diameter-side side seal lip that slidably contacts with the side surface that is present on the side at the side, and a cylindrical surface that exists radially inward with the side surface. An inner diameter side seal lip that is slidably contacted with the curved surface existing in the continuous portion and a radial seal lip that is slidably contacted with the cylindrical surface that is radially inward at the tip edge thereof. It is provided.
In particular, in the rolling bearing unit for supporting a wheel with a seal ring according to the present invention, both the outer diameter side and inner diameter side side seal lips have the smallest thickness and the outer peripheral surface is on the inner diameter side. A minimum thickness portion that is a concave shape that is concave and has a convex shape that the inner peripheral surface protrudes toward the inner diameter side, and a maximum thickness portion that has the largest thickness in the vicinity of the tip edge, respectively, The thickness gradually increases from the minimum thickness portion toward the maximum thickness portion, and the thickness of the maximum thickness portion is more than twice the thickness of the minimum thickness portion .

In the case of the wheel bearing rolling bearing unit with seal ring of the present invention configured as described above, the outer diameter side and the inner diameter side side seal lips are provided near the base end, and the outer peripheral surface is recessed toward the inner diameter side. The concave shape is such that the inner circumferential surface gradually increases from the minimum thickness portion, which is a convex shape protruding toward the inner diameter side, toward the maximum thickness portion existing in the vicinity of the tip edge. Therefore, without bending largely the tip-sided portion of each side seal lip secured by deforming the proximal end portion near the respective side seal lip, to increase the interference, the sealing property (sealing property) it can. In addition, since the maximum thickness portion is provided in the vicinity of the leading edge of each side seal lip , even when the leading edge is worn, it is possible to prevent the portions near the leading edge of each side seal lip from being greatly deformed. Accordingly, an increase in contact load at the sliding contact portion can be suppressed, and ensuring of sealing performance and reduction in torque can be achieved at a high level.

Furthermore, even when the tightening allowance of each side seal lip changes, the change of the contact load at the sliding contact portion can be sufficiently suppressed. That is, each side seal lip has a concave shape with an outer peripheral surface recessed toward the inner diameter side provided in the vicinity of the proximal end portion, and a distal end from a minimum thickness portion having a convex shape with the inner peripheral surface protruding toward the inner diameter side. The thickness gradually increases toward the maximum thickness portion existing in the vicinity of the edge. Therefore, the distal edge of each side seal lip when brought into contact with the mating surface, each section or dimensional errors, errors or assembly, due to the inclination or the like of the center axis of the hub occurs during cornering, each Even when the tightening allowance of the side seal lip is changed, it is possible to prevent the end portion of each side seal lip from being greatly curved. Therefore, the change in the contact area at the sliding contact portion can be suppressed, and the change in the contact load at the sliding contact portion can be sufficiently suppressed, and the torque can be easily reduced.
In particular, since the thickness of the maximum thickness portion is set to be twice or more the thickness of the minimum thickness portion, even when the tightening margin of each side seal lip changes, the contact area of the sliding contact portion is reduced. The change can be further suppressed, and the change in the contact load at the sliding contact portion can be further suppressed. For this reason, the sliding resistance of each side seal lip can be further reduced, and the durability of each side seal lip can be improved. Further, even when the leading edge of each side seal lip is worn, it is possible to sufficiently secure the rigidity of the leading end portion of each side seal lip, and to make the leading end portion more difficult to deform.

Because the present invention acts is constructed as mentioned above, the sealing of security and low torque can be compatible at a high level, moreover, the outer diameter side, the interference of the inner diameter side each side seal lip Even when it changes, the change of the contact load in the said sliding contact part can fully be suppressed.

Preferably, as described in claim 3 , the radial seal lip has a minimum thickness portion having the smallest thickness in the vicinity of the base end portion, and the thickness increases from the minimum thickness portion toward the tip edge. It has a shape in which the maximum thickness portion having the largest thickness is present in the vicinity of the leading edge.

  If comprised in this way, the change of the contact load in the said sliding contact part with respect to the change of the fastening margin of the front-end edge of a radial seal lip can also be suppressed. For this reason, it is possible to achieve both high sealing performance and low torque.

1 and 2 show a first embodiment of the present invention corresponding to claims 1 and 2 . The feature of this example is that the shape of each of the outer-diameter-side and inner-diameter-side side seal lips 18a, 19b constituting the seal ring 13b that closes the outer end opening of the inner space 14 provided with the plurality of rolling elements 11 is devised. As a result, while ensuring both sealing performance and torque reduction at a high level, even when the tightening allowance of each of the side seal lips 18a and 19b changes, the change in the contact load at the sliding contact portion is sufficient. It is in the point to suppress. Since the structure of the other rolling bearing portions is almost the same as that of the conventional structure shown in FIG. 9, the same reference numerals are given to the same portions, and redundant description is omitted, and the characteristic portions of the present invention are hereinafter described. The explanation is centered.

  In the case of this example, the seal ring 13 b is composed of a core metal 16 and a seal material 17. Of these, the metal core 16 is formed in an annular shape as a whole by subjecting a metal plate such as a steel plate to punching processing such as press processing and plastic processing. That is, the cored bar 16 includes a fitting cylinder part 21 and a support plate part 22 that is bent inward in the diameter direction from the axial outer end edge of the fitting cylinder part 21. Of these, the fitting tube portion 21 is freely fitted and fixed to the inner peripheral surface of the outer end portion of the outer ring 8 by an interference fit. For this reason, the outer diameter of the fitting tube portion 21 in a free state is slightly larger than the inner diameter of the outer end opening of the outer ring 8. The support plate 22 has a substantially S-shaped cross-sectional shape, and an outer diameter side inclined cylinder portion 23 that is inclined in a direction toward the axially outer side as it goes radially inward, and the outer diameter side inclined cylinder. An inner diameter side inclined cylindrical portion 24 that is continuously inclined from the inner peripheral edge of the portion 23 toward the inner side in the axial direction as it goes radially inward, and radially inward from the inner peripheral edge of the inner diameter side inclined cylindrical portion 24. And an annular portion 25 that is continuous in the direction in which it faces.

  The sealing material 17 is made of an elastic material such as an elastomer such as rubber, and is insert-molded into the core metal 16 by injection molding, compression molding or the like. The sealing material 17 is bonded and fixed to the metal core 16 by adhesion or the like at the time of molding. The outer peripheral edge portion of such a sealing material 17 covers the outer peripheral surface of the outer diameter side inclined cylindrical portion 23 that constitutes the support plate portion 22 of the core metal 16. Then, the outer diameter in a free state of the portion of the sealing material 17 covering the outer peripheral surface of the outer diameter side inclined cylindrical portion 23 is made slightly larger than the inner diameter of the outer end opening of the outer ring 8. ing. Therefore, in a state where the fitting cylinder portion 21 is fitted and fixed to the outer end opening of the outer ring 8, the outer peripheral edge portion of the sealing material 17 covers the outer peripheral surface of the outer diameter side inclined cylinder portion 23. However, it is elastically pressed between the outer peripheral surface of the outer diameter side inclined cylindrical portion 23 and the inner peripheral surface of the outer end opening of the outer ring 8 to ensure the sealing performance of the portion.

  Further, the base portion 26 of the sealing material 17 completely covers the outer surface of the support plate portion 22 over the entire circumference. Then, an outer diameter side, an inner diameter side, two side seal lips 18 a and 19 b, and one radial seal lip 20 are formed on the outer surface and inner peripheral edge of the base portion 26. The inner surface of the outward flange 3 provided on the outer peripheral surface of the hub 2 in a state where such a seal ring 13b is fitted and fixed to the inner peripheral surface of the outer end opening of the outer ring 8 by an interference fit. The tip edge of the outer diameter side side seal lip 18a is arranged on the entire circumference at a portion that is a continuous portion with the cylindrical surface 34 provided on the outer peripheral surface of the hub 2 and that is outside the curved surface portion 27. It is in contact with slid. Further, the tip edge of the inner diameter side side seal lip 19b is in sliding contact with the curved surface portion 27 over the entire circumference. Further, the leading edge of the radial seal lip 20 is brought into sliding contact with the entire circumference of the cylindrical surface 34 provided on the outer peripheral surface of the hub 2. Then, grease is sealed in a space formed by the outer diameter side, the inner diameter side, the two side seal lips 18 a and 19 b, the one radial seal lip 20, and the hub 2.

  The outer diameter side and inner diameter side side seal lips 18a and 19b are inclined outward in the diameter direction toward the tip edge. The radial seal lip 20 is inclined inward in the axial direction toward the tip edge.

  In particular, in the case of this example, the base end portions of the outer side and inner side side seal lips 18a and 19b are constricted from the outer peripheral surface side toward the central portion in the thickness direction. Minimum thickness portions 28 and 29 are provided. That is, the outer peripheral surface of these minimum thickness parts 28 and 29 is made into the concave shape dented in the inner diameter side. Further, the inner peripheral surfaces of the minimum thickness portions 28 and 29 are formed in a convex shape protruding toward the inner diameter side. The side seal lips 18a and 19b are formed in a shape in which the thickness gradually increases from the minimum thickness portions 28 and 29 toward the front edge, and the front edges of the side seal lips 28 and 29 are formed. In the vicinity, the maximum thickness portions 30 and 31 having the maximum thickness are provided.

Further, a portion of the side seal lip 18a, 19b near the tip, which is located closer to the tip than each of the maximum thickness portions 30, 31, has a tapered shape in which the portion near the outer diameter is removed over the entire circumference. Yes. In the case of this example, the thicknesses t ₃₀ and t ₃₁ (FIG. 2) of the maximum thickness portions 30 and 31 are set to the minimum thickness portions corresponding to the maximum thickness portions 30 and 31, respectively. The thicknesses t ₂₈ and t ₂₉ (FIG. 2) of the portions ₂₈ and ₂₉ are set to be twice or more (t ₃₀ ≧ 2t ₂₈ and t ₃₁ ≧ 2t ₂₉ ). Further, in the case of this example, a minute radius of curvature is formed on a portion including the front edge of each of the outer-diameter-side and inner-diameter-side side seal lips 18a, 19b that is in sliding contact with the inner surface of the outward flange 3 and the curved surface portion 27. A curved surface portion having an arc shape in section is provided over the entire circumference. In the case of this example, the radial seal lip 20 has substantially the same thickness over the entire length.

  In the case of this example, the outer peripheral surface of the base end portion of each of the side seal lips 18a and 19b has a concave shape that is recessed toward the inner diameter side, and the inner peripheral surface of the base end portion protrudes toward the inner diameter side. In addition, this convex shape is made to be smoothly continuous with the part of the inner peripheral surface of each of the side seal lips 18a, 19b that is off the base end.

In the case of the rolling bearing unit for supporting a wheel with a seal ring of the present invention configured as described above, the minimum thickness portion 28 provided with the outer side and inner side side seal lips 18a and 19b in the vicinity of the base end portion. , 29, the thickness gradually increases from the thickest portion 30, 31 in the vicinity of the tip edge. For this reason, it is possible to increase the tightening margin by deforming the vicinity of the base end portion of each side seal lip 18a, 19b without greatly curving the tip portion of each side seal lip 18a, 19b. (Sealability) can be secured. Further, since the maximum thickness portions 30 and 31 are provided in the vicinity of the front end edges of the side seal lips 18a and 19b, even when the front end edges are worn, the portions closer to the front ends of the side seal lips 18a and 19b. Can be prevented from being greatly deformed. Accordingly, an increase in contact load at the sliding contact portion can be suppressed, and ensuring of sealing performance and reduction in torque can be achieved at a high level.

Further, even when the tightening allowance of the side seal lips 18a and 19b changes, the change in the contact load at the sliding contact portion can be sufficiently suppressed. That is, each of the side seal lips 18a and 19b has a shape in which the thickness gradually increases from the minimum thickness portions 28 and 29 provided in the vicinity of the base end portion to the maximum thickness portions 30 and 31 existing in the vicinity of the distal end edge. It is said. For this reason, when the leading edge of each side seal lip 18a, 19b is brought into contact with the mating surface, it is caused by the dimensional error of each part, the assembly error, the inclination of the central axis of the hub 2 that occurs during turning, etc. Thus, even when the tightening margins of the side seal lips 18a and 19b are changed, it is possible to prevent the end seal portions of the side seal lips 18a and 19b from being greatly curved. Accordingly, the contact angles α ₁ and α ₂ between the tip edges of the side seal lips 18a and 19b, the inner surface of the outward flange 3 and the curved surface portion 27 can be sufficiently secured, and the change in the contact area at the sliding contact portion can be ensured. Therefore, the change in the contact load at the sliding contact portion can be sufficiently suppressed, and the torque can be easily reduced.

  Further, in the case of this example, a minute curvature is formed on the portion including the front end edge of each of the outer diameter side and inner diameter side side seal lips 18a and 19b, which is brought into sliding contact with the inner side surface of the outward flange 3 and the curved surface portion 27. A curved surface portion having an arcuate cross section having a radius is provided over the entire circumference. For this reason, in the case of this example, the change (torque fluctuation) of the contact area at the sliding contact portion with respect to the change of the contact load at the sliding contact portion can be further reduced. For example, when the tightening margin between the leading edge of each side seal lip 18a, 19b, the inner surface of the outward flange 3 and the curved surface portion 27 becomes large, the curved surface portion provided at the leading edge portion is elastically deformed. And receiving the contact pressure. Further, the elastic deformation of the curved surface portion can prevent the shape of the tip end edge of each of the side seal lips 18a and 19b slidingly contacting the inner surface of the outward flange 3 and the curved surface portion 27 from being changed greatly. 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 inner side surface of the outward flange 3 and the curved surface portion 27, thereby increasing the sliding torque and promoting wear. Can be further suppressed.

  In addition, it is preferable that the curvature radius of the curved-surface part provided in the part including the front-end | tip edge of each said side seal lip 18a, 19b shall be 0.02-0.1 mm. On the other hand, when the radius of curvature is smaller than 0.02 mm, it is based on the contact load applied to the leading edge of each side seal lip 18a, 19b, the inner surface of the outward flange 3 and the curved surface portion 27. The amount of elastic deformation in the vicinity of the leading edge of each side seal lip 18a, 19b becomes excessive. For this reason, the effect that the change of the contact width (contact area) at the sliding contact portion can be reduced cannot be obtained regardless of the variation of the contact load. On the contrary, when the curvature radius of the curved surface portion provided in the portion including the front edge of each side seal lip 18a, 19b is larger than 0.1 mm, the contact width (contact area) becomes excessive, In addition to an increase in the sliding torque, it becomes easy to bite foreign matter such as dust at the sliding contact portion, and wear is promoted. Furthermore, 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 curvature radius of the curved surface portion provided on each side seal lip is 0.03 to 0.08 mm.

In the present example, the thicknesses t ₃₀ and t ₃₁ of the maximum thickness portion are set to be twice or more the thicknesses t ₂₈ and t ₂₉ of the minimum thickness portions ₂₈ and ₂₉ . For this reason, even when the tightening allowance of each of the side seal lips 18a and 19b changes, the change in the contact area at the sliding contact portion can be further suppressed, and the change in the contact load at the sliding contact portion can be further suppressed. it can. Therefore, the sliding resistance of the side seal lips 18a and 19b can be further reduced, and the durability of the side seal lips 18a and 19b can be improved. Further, even when the leading edge of each of the side seal lips 18a, 19b is worn, the rigidity of the tip of each of the side seal lips 18a, 19b is sufficiently secured, and the tip can be made more difficult to deform.

  In the case of this example, the outer peripheral surface of the base end portion of each of the side seal lips 18a and 19b has a concave shape that is recessed toward the inner diameter side, and the inner peripheral surface of the base end portion protrudes toward the inner diameter side. In addition, this convex shape is made to be smoothly continuous with the part of the inner peripheral surface of each of the side seal lips 18a, 19b that is off the base end. Therefore, the entire base end portions of the side seal lips 18a and 19b 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.

Preferably, the thickness t ₂₉ of the minimum thickness portion 29 of the inner diameter side seal lip 19b of the outer diameter side and inner diameter side seal lips 18a, 19b is set to the minimum thickness of the outer diameter side seal lip 18. thickness portion 28 is made smaller than the thickness t ₂₈ of the (t ₂₉ <t _28), the contact in the case of the inner diameter side side seal the outer contact pressure acting on the leading edge of the lip 19b radially side seal lip 18a Lower than pressure. When such a configuration is adopted, it is possible to easily reduce the torque while ensuring sufficient sealing performance. That is, most of the effect of preventing foreign matter from entering the internal space 14 is performed by the outer diameter side seal lip 18a directly facing the external space where the foreign matter is present. The inner diameter side side seal lip 19b only prevents entry of foreign matter leaked from the sliding contact portion between the outer diameter side side seal lip 18a and the inner side surface of the outward flange 3. For this reason, as described above, even if the contact pressure of the inner diameter side seal lip 19b is lower than the contact pressure of the outer diameter side seal lip 18a, the sealing performance of the entire sealing device is sufficiently obtained. It can be secured. Therefore, by reducing the contact pressure of the inner diameter side side seal lip 19b, it is possible to easily reduce the torque while ensuring sufficient sealing performance.

Next, FIG. 3 shows Embodiment 2 of the present invention corresponding to claims 1 to 3 . In the case of the seal ring 13c incorporated in the wheel support rolling bearing unit with seal ring of this example, unlike the case of the above-described first embodiment, not only the outer side and inner side side seal lips 18a and 19b, but also the radial The seal lip 20a also has a minimum thickness portion 32 having the smallest thickness in the vicinity of the proximal end portion, and the thickness gradually increases from the minimum thickness portion 32 toward the distal end edge. The maximum thickness portion 33 having the largest thickness is assumed to be present. Further, the thickness of the maximum thickness portion 33 is set to be twice or more the thickness of the minimum thickness portion 32. Further, a curved surface portion having an arc-shaped cross section having a minute radius of curvature is provided over the entire circumference at a portion including the tip edge of the radial seal lip 20a that is in sliding contact with the cylindrical surface 34 provided on the hub 2.

In the case of this example configured as described above, it is possible to suppress a change in the contact load at the sliding contact portion with respect to a change in the fastening margin of the tip edge of the radial seal lip 20a. For this reason, it is possible to achieve both lower torque and higher sealing performance at a higher level.
Since other configurations and operations are the same as those in the first embodiment described above, the same reference numerals are given to the equivalent parts, and duplicate descriptions are omitted.

Further, the basic structure of the wheel bearing rolling bearing unit with the seal ring is not limited to the inner ring rotating structure as shown in FIG. 9, but can be applied 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 4a is directly formed on the hub 2 as shown in FIG. Furthermore, the present invention can be applied not only to a structure using balls as rolling elements, but also to a hub unit using other than balls such as tapered rollers.

Next, the results of experiments conducted to confirm the effects of the first embodiment shown in FIGS. First, in the first experiment, the rotational torque of the rolling bearing unit for supporting a wheel with a seal ring was obtained under the condition that the seal life could be achieved for 200 hours, which is the required reference time. In this first experiment, three types of seal rings were used: an example belonging to the technical scope of the present invention, and comparative examples 1 and 2 outside the technical scope. Further, as an embodiment of these, a seal ring having the same structure as that of the first embodiment shown in FIGS. 1 and 2 described above, and the thickness t ₂₉ of the minimum thickness portion 29 of the inner diameter side side seal lip 19b (see FIG. 2) was made smaller than the thickness t ₂₈ (FIG. 2) of the minimum thickness portion 28 of the outer diameter side seal lip 18a. Further, as Comparative Example 1, the same structure as the seal ring of the first example of the conventional structure shown in FIG. 10 is used, and as the Comparative Example 2, the structure of the conventional structure shown in FIG. Those having the same structure as the two seal rings were used. Then, the three types of seal rings of the example and the comparative examples 1 and 2 are sequentially incorporated into the wheel support rolling bearing unit as shown in FIG. 9 to obtain a wheel support rolling bearing unit with a seal ring. The cycle of supplying and discharging muddy water in which Kanto loam powder and salt were dissolved was repeated at regular intervals up to the central axis position. Further, the relative rotational speed between the hub 2 and the outer ring 8 was set to 1000 min ^−1, and the hub (shaft) was set to 0.4 mm TIR (total indicator reading) with respect to the outer ring 8. “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 rotational torque was obtained under the conditions when the seal life reached 200 hours with the three types of wheel bearing rolling bearing units with seal rings under such conditions. It is assumed that the seal life has been reached when the muddy water has entered the inside of the radial seal lip 20 (the muddy water has passed through the three seal lips 18a, 19b, 20). Further, in order to eliminate the influence of the tightening allowance of each seal lip 18a, 19b, 20 in the first experiment, each of these three types of seal lips 18a, 19b, 20 between the wheel bearing rolling bearing units with seal rings is used. The same allowance was used. Then, for each of these three types of wheel bearing rolling bearing units with seal rings , the thicknesses of the side seal lips 18a and 19b on the outer diameter side and the inner diameter side are changed variously, so that each of the side seal lips 18a and 19b is changed. The contact pressure between the tip edge and the mating surface was changed in various ways so that the seal life reached 200 hours. Then, the rotational torque of each wheel support rolling bearing unit with a seal ring was obtained under the conditions (the thickness of each side seal lip 18a, 19b) when this seal life reached 200 hours.

FIG. 4 shows the result of the first experiment conducted in this way. The vertical axis in FIG. 4 represents the rotational torque of each wheel support rolling bearing unit with a seal ring as a relative value when the rotational torque in Comparative Example 1 is 10. As is apparent from the results of the first experiment shown in FIG. 4, in the case of the rolling bearing unit for supporting a wheel with a seal ring according to the present invention, when sufficient sealing performance can be secured, the rotational torque is compared with the comparative example. It was reduced to about 50% for 1 and about 35% for Comparative Example 2.

Next, according to the embodiment used in the first experiment, even when the tightening margin of the outer diameter side seal lip 18a changes, the sliding contact portion between the tip edge of the outer diameter side seal lip 18a and the mating surface The result of the first simulation performed to confirm that the effect that it can suppress the change in contact load at 1 is obtained will be described. This first simulation was carried out with the structure of a wheel bearing rolling bearing unit with a seal ring incorporating two types of seal rings, the above example and the comparative example 1 used in the first experiment. Since the tip edge of the inner diameter side side seal lip 19b is brought into sliding contact with the curved surface portion 27 existing on the outer peripheral surface of the hub 2, it is possible to measure a tightening margin, a contact load, and the like between the tip edge and the curved surface portion 27. Difficult and measurement errors can be large. For this reason, in the simulation and experiment described below including the first simulation, only the outer-diameter side side seal lip 18a of the outer-diameter side and inner-diameter side seal lips 18a and 19b was performed. Further, the shape and thickness of the outer diameter side seal lip 18a in the case where the seal life of 200 hours was ensured in the first experiment were substantially the same in the comparative example 1 and the comparative example 2. For this reason, only the comparative example 1 was compared with the Example in the simulation and experiment demonstrated below including a 1st simulation.

The first simulation is a wheel bearing rolling bearing unit with a seal ring that incorporates two types of seal rings, the example and the comparative example 1, with respect to changes in the tightening allowance of the outer side seal lip 18a. The change in contact load at the sliding contact portion was determined. 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. 5 shows the result of the first simulation performed in this way. In FIG. 5, “min” shown on the horizontal axis represents the minimum value of the above-described tightening allowance, “mid” represents the intermediate value of this allowance, and “max” represents the maximum value of this allowance. . Further, the contact load indicated by the vertical axis in FIG. 5 is expressed as a relative value when the contact load is 10 when the tightening margin of Comparative Example 1 is “max”. As is clear from the result of the first simulation shown in FIG. 5, in the case of the embodiment, the minimum thickness portion 28 having the minimum thickness is provided in the vicinity of the base end portion of the outer diameter side seal lip 18a. Therefore, even when the tightening allowance is changed, the change in the contact load at the sliding contact portion can be suppressed. On the other hand, in the case of Comparative Example 1, when the tightening allowance changed, the contact load at the sliding contact portion changed greatly.

Next, as a second simulation, a wheel bearing rolling bearing unit with a seal ring in which two types of seal rings of the embodiment used in the first simulation and the comparative example 1 are incorporated, an outer diameter side seal lip The change in the contact angle between the tip edge of the outer diameter side side seal lip 18a and the inner surface of the outward flange 3 with respect to the change in the tightening allowance of 18a was determined. In addition, the above-described tightening allowance includes three types, ie, the minimum, maximum and intermediate values 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. Four types including a free state of the outer diameter side side seal lip 18a). The contact angle when the tightening margin is 0 is such that the seal ring 13b and the outward flange 3 are coaxially arranged, the free end of the outer diameter side seal lip 18a, and the outward flange. The angle formed by the inner surface of 3 was used. FIG. 6 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. 6 are the same as those in FIG. Further, the contact angle indicated by the vertical axis in FIG. 6 is expressed as a relative value when the contact angle when the tightening margin of the outer diameter side side seal lip 18a is 0 is 10. As is clear from the results of the second simulation shown in FIG. 6, in the case of the above embodiment, even when the tightening allowance is changed, the leading edge of the outer diameter side side seal lip 18a and the inner flange 3 A good contact angle with the side surface was secured.

Next, as a third simulation, a wheel bearing rolling bearing unit with a seal ring incorporating the two types of seal rings of the example and the comparative example 1 used in the first and second simulations described above, the outer diameter side The change in the dimension (contact width) in the radial direction of the sliding contact portion with respect to the change in the tightening allowance of the side seal lip 18a was obtained. 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. 7 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. 7 are the same as those in FIGS. Further, the contact width indicated by the vertical axis in FIG. 7 is expressed as a relative value when the contact width is 10 when the tightening margin of the outer diameter side seal lip 18a of Comparative Example 1 is “max”. As is apparent from the result of the third simulation shown in FIG. 7, in the case of the above embodiment, even if the tightening allowance is changed, the leading edge of the outer diameter side side seal lip 18a and the inner flange 3 The increase in the area of the contact portion with the side surface could be suppressed.

Next, it is confirmed that the structure of the first embodiment shown in FIGS. 1 and 2 can obtain the effect that the sag of the outer diameter side side seal lip 18a can be suppressed even after a long period of time. I will explain the second experiment. This second experiment used a wheel bearing rolling bearing unit with a seal ring in which two types of seal rings of the example used in the first experiment and the comparative example 1 were incorporated. In addition, the axial tightening margin between the distal end edge of the outer diameter side seal lip 18a and the outward flange 3 in these examples and the comparative example 1 is based on the dimensional error of each part such as the seal material and the assembly error. The intermediate value (mid) of the variable tightening allowance was used. And after leaving such an Example and the comparative example 1 in the thermostat of 60 degreeC temperature, it takes out for every fixed time passage, and the axial direction in the free state of the outer diameter side side seal lip 18a The change in dimension (height) was determined as the amount of sag. The experiment was terminated when the sag of the outer-diameter side seal lip 18a of the above embodiment was almost settled. FIG. 8 shows the result of the second experiment performed in this way. In addition, the amount of sag shown by the vertical axis in FIG. 8 is expressed as a relative value when the amount of sag of Comparative Example 1 at the end of the experiment is 10.

  As is apparent from the results of the second experiment shown in FIG. 8, in the case of the above-described embodiment, it is possible to suppress excessive stress from being concentrated on a part of the outer-diameter side seal lip 18a. Even after the lapse, the amount of sag of the outer diameter side side seal lip 18a can be reduced.

The figure similar to FIG. 10 which shows Example 1 of this invention. The partial expanded sectional view of FIG. The figure similar to FIG. 1 which shows Example 2 of this invention. The graph which shows the 1st experimental result performed in order to confirm the effect of Example 1, comparing the rotational torque on the conditions when the seal life reaches 200 hours. The diagram which similarly shows the result of a 1st simulation by the relationship between the interference of the outer diameter side 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 interference of the outer diameter 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 fastening allowance of an outer diameter side seal lip, and the contact width (dimension regarding a radial direction) in the said sliding contact part. The diagram which similarly shows a 2nd experimental result by the relationship between elapsed time and the amount of sag of an outer diameter side side seal lip. Sectional drawing which shows an example of the rolling bearing unit for wheel support with a seal ring used as the object of this invention. FIG. 10 is an enlarged view of a portion A in FIG. 9 showing a seal ring of a first example having a conventional structure. The figure similar to FIG. 10 which shows the seal ring of the 2nd example.

DESCRIPTION OF SYMBOLS 1 Inner ring element 2 Hub 3 Outward flange 4a, 4b Inner ring raceway 5 Step part 6 Male thread part 7 Nut 8 Outer ring 9 Mounting part 10a, 10b Outer ring raceway 11 Rolling body 12 Cage 13, 13a-13c Seal ring 14 Internal space 15 Cover 16 Core 17 Seal material 18, 18a Outer diameter side seal lip 19, 19a, 19b Inner diameter side seal lip 20, 20a Radial seal lip 21 Fitting cylinder part 22 Support plate part 23 Outer diameter side inclined cylinder part 24 Inner diameter side inclination Cylindrical portion 25 Annular portion 26 Base portion 27 Curved portion 28 Minimum thickness portion 29 Minimum thickness portion 30 Maximum thickness portion 31 Maximum thickness portion 32 Minimum thickness portion 33 Maximum thickness portion 34 Cylindrical surface

Claims (3)

The outer ring has a double row outer ring raceway on the inner peripheral surface, the outer ring does not rotate when in use , the double row inner ring raceway on the part of the outer peripheral surface facing each outer ring raceway, and the outer ring on the remaining part of the outer peripheral surface. Each part has an outward flange at a part protruding from the opening at one end, and a plurality of rolling members provided in a freely rotatable manner between the inner ring member and the inner ring equivalent member that rotates together with the wheel during use. and body, and a sealing ring which closes the annular gap between the end opening and the inner ring member of the outer ring, the seal ring, the outer peripheral surface of the inner ring member rotating in the inner diameter side of the outer ring and the for closing the space between the inner circumferential surface of the outer ring, provided with a sealing material made annularly the whole of an elastic material, the whole periphery the sealing material, during use, on the side there respective distal edge laterally The outer diameter side seal lip , And a radially inner, side seal lip sliding contact over the entire circumference the curved surface portions existing continuous portion of a cylindrical surface which is present in the side surface and radially inwardly, there its leading edge in the radially inward In the wheel bearing rolling bearing unit with a seal ring, which is provided with a radial seal lip that is slidably contacted with the entire circumference of the cylindrical surface, each of the outer diameter side and inner diameter side seal lips has a base end portion. In the vicinity, the smallest thickness part having the smallest thickness and the outer peripheral surface recessed toward the inner diameter side and the inner peripheral surface projecting toward the inner diameter side has a minimum thickness portion near the tip edge. The largest maximum thickness portion exists, and the thickness gradually increases from the minimum thickness portion toward the maximum thickness portion. The thickness of the maximum thickness portion is the minimum thickness portion. the thickness of more than twice that for the seal ring with the wheel support, characterized in that the Galli bearing unit. 2. The wheel with seal ring according to claim 1 , wherein a curved surface portion having a cross-sectional arc shape having a radius of curvature of 0.02 to 0.1 mm is provided on a portion including a tip edge of the side seal lip over the entire circumference. Rolling bearing unit for support. The radial seal lip has the smallest thickness part in the vicinity of the base end, and the thickness gradually increases from the minimum thickness part toward the tip edge. The rolling bearing unit for supporting a wheel with a seal ring according to any one of claims 1 to 2 , wherein the rolling bearing unit has a shape in which the largest thickness portion is present.

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