Sealing device and wheel bearing device

Abstract

This sealing device makes it possible to prevent an increase in rotational torque by suppressing wear of a seal lip, and to prevent deterioration of muddy water resistance caused by a decrease in an interference of the seal lip. In the sealing device, a seal lip 42 has first and second seal lip-side slide surfaces 46, 47 that contact a slinger 20 via grease. The slinger 20 has first and second slinger-side slide surfaces 24, 25 that contact the seal lip 42 via grease G1, G2. Either the first and second seal lip-side slide surfaces 46, 47 or the first and second slinger-side slide surfaces 24, 25 have protrusions and recesses. The grease G1, G2 contains a base oil and a thickener. The thickener has a peak of particle size distribution of 10 μm or less.

Description

Sealing device and wheel bearing device

[0001] The present invention relates to a sealing device and a wheel bearing device.

[0002] Various techniques related to sealing devices for sealing the opening of the space between an outer member and an inner member of a wheel bearing device are known. Further, Patent Document 1 describes a sealing device that has a seal lip slidably in close contact with a counterpart member, provides unevenness on the sliding surface of the seal lip, and supplies grease with a low base oil viscosity to the sliding surface of the seal lip. The unevenness on the sliding surface of the seal lip in this sealing device has a size of 1.5 to 3.0 µmRa, and the low base oil viscosity grease is a grease having a base oil kinematic viscosity of 10 to 40 mm² / S at 40°C. This configuration achieves low friction accompanying sliding and suppresses lip wear.

[0003] Japanese Patent No. 5757455

[0004] However, in the sealing device described in Patent Document 1, the formation of unevenness on the sliding surface of the seal lip increases the surface pressure acting on the sliding surface, which may make the sliding surface of the seal lip more prone to wear. Such wear of the seal lip may lead to an increase in rotational torque, and a decrease in the interference of the seal lip, which may result in a decrease in muddy water resistance.

[0005] Accordingly, an object of the present invention is to provide a sealing device or a wheel bearing device including the sealing device, which can suppress wear of the seal lip, prevent an increase in rotational torque, and prevent a decrease in muddy water resistance caused by a reduction in the interference of the seal lip.

[0006] That is, a sealing device for sealing the opening of the space between an outer member and an inner member of a wheel bearing device, comprising: a slinger fitted to the inner member; a core metal fitted to the outer member; an elastic member joined to the core metal and having a seal lip extending toward the slinger; and grease filled between the seal lip and the slinger, wherein the seal lip has a seal lip side sliding surface that contacts the slinger via the grease; the slinger has a slinger side sliding surface that contacts the seal lip via the grease; irregularities are formed on either the seal lip side sliding surface or the slinger side sliding surface; the grease contains a base oil and a thickener; and the thickener has a particle size distribution peak of 10 μm or less.

[0007] Furthermore, a wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces; double rows of rolling elements rotatably housed between the raceway surfaces of the outer member and the inner member; and a sealing device that closes the open end of the annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted into the outer member; an elastic member joined to the core metal and having a seal lip extending toward the inner member; and grease filled between the seal lip and the inner member, wherein the seal lip has a seal lip side sliding surface that contacts the inner member via the grease; the inner member has an inner member side sliding surface that contacts the seal lip via the grease; and irregularities are formed on either the seal lip side sliding surface or the inner member side sliding surface; and the grease contains a base oil and a thickener. The aforementioned thickener has a particle size distribution peak of 10 μm or less.

[0008] The present invention provides the following effects. Specifically, it is possible to suppress wear of the seal lip and prevent an increase in rotational torque, and to prevent a decrease in the seal lip's interference fit and a reduction in water resistance.

[0009] A cross-sectional view showing a wheel bearing device according to one embodiment of the present invention. An enlarged cross-sectional view showing the periphery of the inner seal member of the wheel bearing device. An enlarged cross-sectional view showing the periphery of the outer seal member of the wheel bearing device. A cross-sectional view showing a wheel bearing device. An enlarged cross-sectional view showing the periphery of the inner seal member of the wheel bearing device. An enlarged cross-sectional view showing the periphery of the outer seal member of the wheel bearing device. A diagram showing the particle size distribution of the grease thickener of the wheel bearing device.

[0010] The embodiments for carrying out the present invention will be described below with reference to the attached drawings.

[0011] [Overall Configuration of Wheel Bearing Device] The wheel bearing device 1 shown in Figures 1 to 3 will be described below. The wheel bearing device 1 shown in Figure 1 is one embodiment of the wheel bearing device according to the present invention, and supports a wheel so as to be rotatable in the suspension system of a vehicle such as an automobile.

[0012] As shown in Figure 1, the wheel bearing device 1 has a configuration referred to as the third generation, and comprises an outer ring 2 which is an outer member, a hub ring 3 and an inner ring 4 which are inner members, two rows of inner ball rows 5 and outer ball rows 6 which are rolling rows, an inner sealing member 9 and an outer sealing member 10.

[0013] Here, "inner side" refers to the side of the wheel bearing device 1 that is attached to the vehicle body, and "outer side" refers to the side of the wheel bearing device 1 that is attached to the vehicle body. Furthermore, "axial direction" refers to the direction along the rotation axis X of the wheel bearing device 1. The direction perpendicular to the rotation axis of the wheel bearing device 1 is referred to as the radial direction. The direction along the arc centered on the rotation axis of the wheel bearing device 1 is referred to as the circumferential direction. In the following, "cross-section" will be described as a cross-section that passes through the rotation axis of the wheel bearing device 1 and is parallel to the rotation axis of the wheel bearing device 1.

[0014] As shown in Figures 1 to 3, the outer ring 2 has an inner outer raceway surface 2c and an outer outer raceway surface 2d. The inner outer raceway surface 2c and the outer outer raceway surface 2d are formed on the inner circumference of the outer ring 2. The inner outer raceway surface 2c is located on the inner side of the outer outer raceway surface 2d. A vehicle body mounting flange for attaching the outer ring 2 to a vehicle body side member is integrally formed on the outer circumference of the outer ring 2. The inner end 2e of the outer ring 2 is located on the inner side of the inner outer raceway surface 2c. The outer end 2f of the outer ring 2 is located on the outer side of the outer outer raceway surface 2d.

[0015] A small-diameter stepped portion 3a is formed at the inner end of the outer circumference of the hub wheel 3, which is smaller in diameter than the outer end of the hub wheel 3 and extends in the axial direction. A wheel mounting flange 3b for attaching a wheel is integrally formed at the outer end of the hub wheel 3. Multiple bolt holes 3c are formed in the wheel mounting flange 3b. Hub bolts 3d are press-fitted into the bolt holes 3c from the inner side to fasten the hub wheel 3 to a wheel or brake component. Alternatively, the structure for fastening the hub wheel 3 to a wheel or brake component may be fixed by wheel bolts.

[0016] The hub ring 3 has an inner raceway surface 3e on the outer side. The inner raceway surface 3e on the outer side is formed on the outer circumference of the hub ring 3 so as to face the outer raceway surface 2d on the outer side of the outer ring 2. In other words, the inner raceway surface 3e on the outer side is formed by the hub ring 3 on the outer side of the inner member. An annular space, the outer side opening 2b, is formed between the outer ring 2 and the hub ring 3. The outer side sealing member 10 is fitted into the outer side opening 2b to seal the outer side opening 2b and prevent foreign matter such as muddy water from entering through the outer side opening 2b. The outer side sealing member 10 is an example of a sealing device.

[0017] The wheel mounting flange 3b of the hub wheel 3 is located on the outer side of the inner raceway surface 3e on the outer side. The flange 3b has a flange side surface 3f facing the inner side. The flange side surface 3f is composed of a flat surface parallel to the radial direction. The vicinity of the bolt hole 3c on the flange side surface 3f is configured as a seating surface when the hub bolt 3d is fastened. A predetermined space is formed between the flange side surface 3f and the outer end 2f of the outer ring 2.

[0018] The hub wheel 3 has a base portion 3g of the wheel mounting flange 3b between the wheel mounting flange 3b (flange side surface 3f) and the inner raceway surface 3e on the outer side. The base portion 3g has a radial surface 3h, an axial surface 3i, an arc-shaped surface 3j, and an outer diameter side surface 3k.

[0019] The radial surface 3h of the hub ring 3 is composed of a straight surface parallel to the radial direction. The radial surface 3h is located on the inner diameter side of the flange side surface 3f. A predetermined space is formed between the radial surface 3h and the outer end 2f of the outer ring 2. The axial surface 3i is composed of a straight surface parallel to the axial direction. The axial surface 3i is located on the outer diameter side and outer side of the outer inner raceway surface 3e, and on the inner diameter side and inner side of the radial surface 3h. The inner end of the axial surface 3i is connected to the outer end of the inner raceway surface 3e. A predetermined space is formed between the axial surface 3i and the outer end 2f of the outer ring 2. The arc-shaped surface 3j is composed of a surface that is concave toward the inner diameter side. The arc-shaped surface 3j is located on the inner diameter side of the radial surface 3h and on the outer side of the axial surface 3i. The inner end of the arc-shaped surface 3j is connected to the outer end of the axial surface 3i. The outer diameter end of the arc-shaped surface 3j is connected to the inner diameter end of the radial surface 3h. A predetermined space is formed between the arc-shaped surface 3j and the outer end 2f of the outer ring 2. The outer diameter side surface 3k is composed of a straight surface that is generally parallel to the axial direction. The outer diameter side surface 3k is located on the outer diameter side and outer side of the radial surface 3h, and on the inner diameter side and inner side of the flange side surface 3f. The inner end of the outer diameter side surface 3k is connected to the outer diameter end of the radial surface 3h. The outer end of the outer diameter side surface 3k is connected to the inner diameter end of the flange side surface 3f.

[0020] The inner ring 4 is press-fitted into the small-diameter stepped portion 3a of the hub ring 3 and is provided on the hub ring 3. The inner ring 4 is integrated with the hub ring 3 by a crimped portion that is plastically deformed by crimping the inner end of the small-diameter stepped portion 3a on the hub ring 3.

[0021] The inner ring 4 has an inner raceway surface 4a on the inner side. The inner raceway surface 4a on the inner side is formed on the outer circumference of the inner ring 4 so as to face the outer raceway surface 2c on the inner side of the outer ring 2. In other words, the inner raceway surface 4a is formed on the inner side of the inner member by the inner ring 4. The inner end 4b of the inner ring 4 is located on the inner side of the inner raceway surface 4a on the inner side. A predetermined space is formed between the inner end 4b of the inner ring 4 and the inner end 2e of the outer ring 2. An annular space, the inner side opening 2a, is formed between the outer ring 2 and the inner ring 4. The inner side sealing member 9 is fitted into the inner side opening 2a to seal the inner side opening 2a and prevent foreign matter such as muddy water from entering through the inner side opening 2a. The inner side sealing member 9 is an example of a sealing device.

[0022] The inner ball row 5 is composed of multiple balls 7, which are rolling elements, held by a cage 8. The outer ball row 6 is composed of multiple balls 7, which are rolling elements, held by a cage 8. The cage 8 is formed in a substantially annular shape, and the axis of rotation of the cage 8 coincides with the axis of rotation X. The inner ball row 5 is rotatably sandwiched between the inner raceway surface 4a on the inner side of the inner ring 4 and the outer raceway surface 2c on the inner side of the outer ring 2. The outer ball row 6 is rotatably sandwiched between the inner raceway surface 3e on the outer side of the hub ring 3 and the outer raceway surface 2d on the outer side of the outer ring 2. In other words, the inner ball row 5 and the outer ball row 6 are rotatably housed between the respective raceway surfaces of the outer and inner members. In the wheel bearing device 1, a double-row angular contact ball bearing is composed of the outer ring 2, the hub ring 3 and the inner ring 4, the inner ball row 5 and the outer ball row 6.

[0023] [Specific configuration of the inner sealing member] As shown in Figure 2, the inner sealing member 9 comprises a slinger 20, a core metal 30, and a core metal side elastic member 40.

[0024] The slinger 20 is configured in a substantially annular shape and is fitted onto the inner ring 4. The slinger 20 is formed from a metal member, for example, stainless steel, and has a substantially U-shaped cross-section. The slinger 20 has an outer fitting portion 21, an annular portion 22, and an outer diameter portion 23.

[0025] The outer fitting portion 21 of the slinger 20 is cylindrical and fits onto the outer circumference of the inner end portion 4b of the inner ring 4. The outer fitting portion 21 is configured parallel to the axial direction. The annular portion 22 is annular and is located on the outer diameter side of the outer fitting portion 21. The annular portion 22 is configured parallel to the radial direction. The annular portion 22 extends from the outer fitting portion 21 toward the outer diameter side. The inner diameter side end of the annular portion 22 is connected to the inner side end of the outer fitting portion 21. The annular portion 22 may also be configured to have a magnetic encoder, made of synthetic rubber or the like with arranged magnetic poles (N pole and S pole), on its inner side surface. The outer diameter portion 23 is cylindrical and is located on the outer diameter side of the outer fitting portion 21 and the annular portion 22. The outer diameter portion 23 is configured parallel to the axial direction. The outer diameter portion 23 extends from the annular portion 22 toward the outer side. The inner end of the outer diameter portion 23 is connected to the outer diameter end of the annular portion 22.

[0026] The core metal 30 is configured in a substantially annular shape and is fitted inside the outer ring 2. The core metal 30 is positioned such that a predetermined gap is formed between it and the slinger 20, and the core metal 30 and the slinger 20 are configured to be non-contact. The core metal 30 is made of a metal member, for example, stainless steel. The core metal 30 has an inner fitting portion 31 and a vertical plate portion 32.

[0027] The inner fitting portion 31 of the core metal 30 is cylindrical in shape and fits onto the inner circumference of the inner end 2e of the outer ring 2. The inner fitting portion 31 is configured parallel to the axial direction. The vertical plate portion 32 is located on the inner diameter side of the inner fitting portion 31 and extends inward from the inner fitting portion 31. The outer diameter side end of the vertical plate portion 32 is connected to the outer side end of the inner fitting portion 31.

[0028] The core-side elastic member 40 is made of, for example, synthetic rubber and is configured to be elastically deformable. The core-side elastic member 40 is joined to the core 30 by vulcanization bonding or the like. The core-side elastic member 40 is an example of an elastic member. The core-side elastic member 40 has a base portion 41 and a seal lip 42.

[0029] The base 41 of the core metal side elastic member 40 is provided on the core metal 30 so as to cover a part of the core metal 30. The seal lip 42 is configured to be elastically deformable. The seal lip 42 prevents foreign matter such as muddy water from entering between the slinger 20 and the core metal 30. The seal lip 42 is provided on the base 41 and extends toward the slinger 20. The seal lip 42 comprises a first seal lip 43, a second seal lip 44, and a third seal lip 45.

[0030] The first seal lip 43 of the seal lip 42 is configured to be elastically deformable. The first seal lip 43 prevents foreign matter such as muddy water from entering between the slinger 20 and the core metal 30. The first seal lip 43 extends from the vertical plate portion 32 of the core metal 30 toward the outer fitting portion 21 of the slinger 20. The first seal lip 43 extends toward the inner diameter side and the outer side, and contacts the outer diameter side surface of the outer fitting portion 21 of the slinger 20.

[0031] The second seal lip 44 of the seal lip 42 is configured to be elastically deformable. The second seal lip 44 prevents foreign matter such as muddy water from entering between the slinger 20 and the core metal 30. The second seal lip 44 extends from the vertical plate portion 32 of the core metal 30 toward the annular portion 22 of the slinger 20. The second seal lip 44 extends toward the outer diameter side and the inner side, and contacts the outer side surface of the annular portion 22 of the slinger 20.

[0032] The third seal lip 45 of the seal lip 42 is configured to be elastically deformable. The third seal lip 45 prevents foreign matter such as muddy water from entering between the slinger 20 and the core metal 30. The third seal lip 45 extends from the vertical plate portion 32 of the core metal 30 toward the annular portion 22 and the outer diameter portion 23 of the slinger 20. The third seal lip 45 is located on the inner diameter side of the outer diameter portion 23 of the slinger 20. The third seal lip 45 extends toward the outer diameter side and the inner side, and is configured to be non-contact with the annular portion 22 and the outer diameter portion 23 of the slinger 20. Note that either the first seal lip 43 or the second seal lip 44 of the seal lip 42 may be configured to be non-contact with the slinger 20. Also, the seal lip 42 may be configured without one or two of the first seal lip 43, the second seal lip 44, and the third seal lip 45.

[0033] The gap between the base 41 of the core metal side elastic member 40 and the outer diameter portion 23 of the slinger 20, and the gap between the third seal lip 45 of the core metal side elastic member 40 and the outer diameter portion 23 of the slinger 20 are configured as a labyrinth. By configuring the labyrinth in this way, foreign matter such as muddy water is prevented from entering between the slinger 20 and the core metal 30.

[0034] The inner side seal member 9 is equipped with grease G1 and G2. Grease G1 and G2 are filled between the seal lip 42 of the core metal side elastic member 40 and the slinger 20. Grease G1 and G2 are bearing greases and contain a base oil and a thickener. The base oil kinematic viscosity of grease G1 and G2 at 40°C is 65 mm² / S. The thickener of grease G1 and G2 is, for example, a urea-based thickener. The particle size distribution peak of the thickener of grease G1 and G2 is 10 μm or less (see Figure 7), and the particle size is relatively small. The particle size distribution of the thickener of grease G1 and G2 is measured by, for example, laser diffraction scattering, dynamic light scattering, or dynamic image analysis.

[0035] The first seal lip 43 of the seal lip 42 of the core metal side elastic member 40 has a first seal lip side sliding surface 46. The first seal lip side sliding surface 46 contacts the outer fitting portion 21 of the slinger 20 via grease G1. The first seal lip side sliding surface 46 is an example of a seal lip side sliding surface. The outer fitting portion 21 of the slinger 20 has a first slinger side sliding surface 24. The first slinger side sliding surface 24 contacts the first seal lip 43 of the seal lip 42 of the core metal side elastic member 40 via grease G1. The first slinger side sliding surface 24 is an example of a slinger side sliding surface. Irregularities are formed on either the first seal lip side sliding surface 46 of the seal lip 42 of the core metal side elastic member 40 or the first slinger side sliding surface 24 of the slinger 20. On either the first seal lip side sliding surface 46 of the seal lip 42 of the core metal side elastic member 40 or the first slinger side sliding surface 24 of the slinger 20, no irregularities are formed on the other, and a smooth surface with a typical surface roughness is formed.

[0036] The second seal lip 44 of the seal lip 42 of the core metal side elastic member 40 has a second seal lip side sliding surface 47. The second seal lip side sliding surface 47 contacts the annular portion 22 of the slinger 20 via grease G2. The second seal lip side sliding surface 47 is an example of a seal lip side sliding surface. The annular portion 22 of the slinger 20 has a second slinger side sliding surface 25. The second slinger side sliding surface 25 contacts the second seal lip 44 of the seal lip 42 of the core metal side elastic member 40 via grease G2. The second slinger side sliding surface 25 is an example of a slinger side sliding surface. Irregularities are formed on either the second seal lip side sliding surface 47 of the seal lip 42 of the core metal side elastic member 40 or the second slinger side sliding surface 25 of the slinger 20. On either the second seal lip side sliding surface 47 of the seal lip 42 of the core metal side elastic member 40 or the second slinger side sliding surface 25 of the slinger 20, no irregularities are formed on the other, and a smooth surface with a typical surface roughness is formed.

[0037] As described above, irregularities are formed on either the first seal lip side sliding surface 46 of the seal lip 42 of the core metal side elastic member 40 or the first slinger side sliding surface 24 of the slinger 20. Also, irregularities are formed on either the second seal lip side sliding surface 47 of the seal lip 42 of the core metal side elastic member 40 or the second slinger side sliding surface 25 of the slinger 20. This configuration improves the interposition of grease G1 and G2 on the sliding surfaces (first seal lip side sliding surface 46, first slinger side sliding surface 24, second seal lip side sliding surface 47, and second slinger side sliding surface 25).

[0038] Furthermore, as described above, the particle size distribution peak of the thickeners G1 and G2 in the inner side seal member 9 is 10 μm or less. By configuring the particle size of the thickeners in the grease G1 and G2 to be relatively small in this way, the interposition of the grease G1 and G2 to the sliding surfaces (first seal lip side sliding surface 46, first slinger side sliding surface 24, second seal lip side sliding surface 47, and second slinger side sliding surface 25) can be improved, and an increase in surface pressure on the sliding surfaces can be suppressed. For this reason, even if the sliding surfaces are configured to have irregularities, wear of the seal lip 42 of the core metal side elastic member 40 that contacts the slinger 20 can be suppressed. Consequently, an increase in rotational torque due to wear of the seal lip 42 of the core metal side elastic member 40 can be prevented. In addition, a decrease in the tightening allowance of the seal lip 42 of the core metal side elastic member 40 and a decrease in mud-water resistance can be prevented due to wear of the seal lip 42 of the core metal side elastic member 40.

[0039] The surface roughness of the irregularities formed on either the first seal lip side sliding surface 46 of the seal lip 42 of the core metal side elastic member 40 or the first slinger side sliding surface 24 of the slinger 20 is 0.5 μmRa to 5.0 μmRa. Also, the surface roughness of the irregularities formed on either the second seal lip side sliding surface 47 of the seal lip 42 of the core metal side elastic member 40 or the second slinger side sliding surface 25 of the slinger 20 is 0.5 μmRa to 5.0 μmRa. By configuring it in this way, the interposition of grease G1 and G2 on the sliding surfaces (first seal lip side sliding surface 46, first slinger side sliding surface 24, second seal lip side sliding surface 47, and second slinger side sliding surface 25) can be further improved. Therefore, even if the sliding surface is configured to have irregularities, wear of the seal lip 42 of the core metal side elastic member 40 that contacts the slinger 20 can be suppressed. Consequently, it is possible to prevent an increase in rotational torque due to wear of the seal lip 42 of the core metal side elastic member 40. Furthermore, it is possible to prevent a decrease in the tightening allowance of the seal lip 42 of the core metal side elastic member 40 and a reduction in mud-water resistance due to wear of the seal lip 42 of the core metal side elastic member 40.

[0040] Furthermore, in order to further improve the interposition of grease G1 and G2, it is preferable that the surface roughness of the irregularities formed on either the first seal lip side sliding surface 46 of the seal lip 42 of the core metal side elastic member 40 or the first slinger side sliding surface 24 of the slinger 20 is greater than 3.0 μmRa and 5.0 μmRa or less. Furthermore, in order to further improve the interposition of grease G1 and G2, it is preferable that the surface roughness of the irregularities formed on either the second seal lip side sliding surface 47 of the seal lip 42 of the core metal side elastic member 40 or the second slinger side sliding surface 25 of the slinger 20 is greater than 3.0 μmRa and 5.0 μmRa or less.

[0041] [Specific configuration of the outer sealing member] As shown in Figure 3, the outer sealing member 10 comprises a slinger 50, a slinger-side elastic member 60, a core metal 70, and a core metal-side elastic member 80.

[0042] The slinger 50 is formed in a substantially annular shape and is externally fitted onto the hub wheel 3. The slinger 50 is formed of a metal member made of, for example, a stainless steel material, and has a substantially U-shaped cross-section. The slinger 50 includes an externally fitted portion 51, an annular portion 52, a connecting portion 53, and a protruding portion 54.

[0043] The externally fitted portion 51 of the slinger 50 is formed in a cylindrical shape and fitted onto the axial surface 3i of the hub wheel 3. The externally fitted portion 51 is configured parallel to the axial direction. The annular portion 52 is formed in an annular shape, and is located on the outer diameter side and the outer side relative to the externally fitted portion 51. The annular portion 52 is configured parallel to the radial direction. The annular portion 52 is located on the inner side of the radial surface 3h of the hub wheel 3. The connecting portion 53 is disposed between the externally fitted portion 51 and the annular portion 52. The connecting portion 53 connects the externally fitted portion 51 and the annular portion 52, and is inclined with respect to the axial direction. The inner end of the connecting portion 53 is connected to the outer end of the externally fitted portion 51, and the outer diameter end of the connecting portion 53 is connected to the inner diameter end of the annular portion 52. The protruding portion 54 is formed in a cylindrical shape, and is located on the outer diameter side relative to the externally fitted portion 51, the annular portion 52, and the connecting portion 53. The protruding portion 54 is configured parallel to the axial direction. The protruding portion 54 extends toward the inner side from the annular portion 52. The outer end of the protruding portion 54 is connected to the outer diameter end of the annular portion 52.

[0044] The slinger-side elastic member 60 is made of, for example, synthetic rubber, and is configured to be elastically deformable. The slinger-side elastic member 60 is joined to the slinger 50 by vulcanization adhesion or the like. The slinger-side elastic member 60 protrudes toward the outer diameter side from the protruding portion 54 of the slinger 50.

[0045] The core metal 70 is formed in a substantially annular shape and is internally fitted onto the outer ring 2. The core metal 70 is disposed such that a predetermined gap is formed between the core metal 70 and the slinger 50, and the core metal 70 and the slinger 50 are configured to be non-contact with each other. The core metal 70 is formed of a metal member made of, for example, a stainless steel material, and has a crank-shaped cross-section. The core metal 70 includes a fitting portion 71, an inner diameter portion 72, an annular portion 73, and a protruding portion 74. It should be noted that the core metal 70 may be configured to be externally fitted onto the outer ring 2.

[0046] The fitting portion 71 of the core metal 70 is formed in a cylindrical shape and is fitted onto the inner circumference of the outer side end portion 2f of the outer ring 2. The fitting portion 71 is configured to be parallel to the axial direction. The inner diameter portion 72 is located closer to the inner diameter side than the fitting portion 71, and extends from the fitting portion 71 toward the inner diameter side. The outer diameter side end of the inner diameter portion 72 is connected to the inner side end of the fitting portion 71. The annular portion 73 is located closer to the outer diameter side than the fitting portion 71, and extends from the fitting portion 71 toward the outer diameter side. The inner diameter side end of the annular portion 73 is connected to the outer side end of the fitting portion 71. The annular portion 73 is located on the outer side of the outer side end portion 2f of the outer ring 2, and the inner side surface of the annular portion 73 is in contact with the outer side surface of the outer side end portion 2f of the outer ring 2. The protruding portion 74 is located closer to the inner side than the annular portion 73, and extends from the annular portion 73 toward the inner side. The inner end of the annular portion 73 is connected to the outer diameter side end of the fitting portion 71. The protruding portion 74 is located on the outer diameter side of the outer side end portion 2f.

[0047] The core metal-side elastic member 80 is made of, for example, synthetic rubber, and is configured to be elastically deformable. The core metal-side elastic member 80 is joined to the core metal 70 by vulcanization adhesion or the like. The core metal-side elastic member 80 is an example of an elastic member. The core metal-side elastic member 80 includes a base portion 81, a seal lip 82, and a weir portion 86.

[0048] The base portion 81 of the core metal-side elastic member 80 is provided on the core metal 70 so as to cover a part of the core metal 70. The seal lip 82 is configured to be elastically deformable. The seal lip 82 prevents foreign matter such as muddy water from entering from between the slinger 50 and the core metal 70. The seal lip 82 is provided on the base portion 81 and extends toward the slinger 50. The seal lip 82 includes a first seal lip 83, a second seal lip 84, and a third seal lip 85.

[0049] The first seal lip 83 of the seal lip 82 is configured to be elastically deformable. The first seal lip 83 prevents foreign matter such as muddy water from entering from between the slinger 50 and the core metal 70. The first seal lip 83 extends from the inner diameter portion 72 of the core metal 70 toward the outer fitting portion 51 of the slinger 50. The first seal lip 83 extends toward the inner diameter side and the inner side, and is in contact with the outer diameter side surface of the outer fitting portion 51 of the slinger 50.

[0050] The second seal lip 84 of the seal lip 82 is configured to be elastically deformable. The second seal lip 84 prevents foreign matter such as muddy water from entering between the slinger 50 and the core metal 70. The second seal lip 84 extends from the inner diameter portion 72 of the core metal 70 toward the connection portion 53 of the slinger 50. The second seal lip 84 extends toward the outer side and contacts the inner side surface of the connection portion 53 of the slinger 50.

[0051] The third seal lip 85 of the seal lip 82 is configured to be elastically deformable. The third seal lip 85 prevents foreign matter such as muddy water from entering between the slinger 50 and the core metal 70. The third seal lip 85 extends from the inner diameter portion 72 of the core metal 70 toward the annular portion 52 and the protruding portion 54 of the slinger 50. The third seal lip 85 is located on the inner diameter side of the protruding portion 54 of the slinger 50. The third seal lip 85 extends toward the outer side and is configured not to contact the annular portion 52 and the protruding portion 54 of the slinger 50. Note that either the first seal lip 83 or the second seal lip 84 of the seal lip 82 may be configured not to contact the slinger 50. Also, the seal lip 82 may be configured without one or two of the first seal lip 83, the second seal lip 84, and the third seal lip 85.

[0052] The weir portion 86 of the core metal side elastic member 80 is configured to be elastically deformable. The weir portion 86 prevents foreign matter such as muddy water from entering between the slinger 50 and the hub wheel 3 and between the slinger 50 and the core metal 70. The weir portion 86 extends from the protruding portion 74 of the core metal 70 toward the outer diameter side and the outer side. The weir portion 86 is configured to be non-contact with the radial surface 3g of the hub wheel 3, the annular portion 52 of the slinger 50, the protruding portion 54 of the slinger 50, and the slinger side elastic member 60. A predetermined space is formed between the weir portion 86 and the radial surface 3g of the hub wheel 3, and between the weir portion 86 and the slinger side elastic member 60.

[0053] The gaps between the weir portion 86 of the core metal side elastic member 80 and the radial surface 3g of the hub wheel 3, the gap between the base portion 61 of the core metal side elastic member 80 and the slinger side elastic member 60, the gap between the protruding portion 54 of the slinger 50 and the third seal lip 85 of the core metal side elastic member 80, and the gap between the annular portion 52 of the slinger 50 and the third seal lip 85 of the core metal side elastic member 80 are configured as labyrinths. By configuring the labyrinths in this way, foreign matter such as muddy water is prevented from entering between the slinger 50 and the hub wheel 3 and between the slinger 50 and the core metal 70.

[0054] The outer sealing member 10 is equipped with grease G3 and G4. Grease G3 and G4 are filled between the seal lip 82 of the core metal side elastic member 80 and the slinger 50. Grease G3 and G4 are bearing greases and contain a base oil and a thickener. The base oil kinematic viscosity of grease G3 and G4 at 40°C is 65 mm² / S. The thickener of grease G3 and G4 is, for example, a urea-based thickener. The particle size distribution peak of the thickener of grease G3 and G4 is 10 μm or less (see Figure 7), and the particle size is relatively small. The particle size distribution of the thickener of grease G3 and G4 is measured by, for example, laser diffraction scattering, dynamic light scattering, or dynamic image analysis.

[0055] The first seal lip 83 of the seal lip 82 of the core metal side elastic member 80 has a first seal lip side sliding surface 87. The first seal lip side sliding surface 87 contacts the outer fitting portion 51 of the slinger 50 via grease G3. The first seal lip side sliding surface 87 is an example of a seal lip side sliding surface. The outer fitting portion 51 of the slinger 50 has a first slinger side sliding surface 55. The first slinger side sliding surface 55 contacts the first seal lip 83 of the seal lip 82 of the core metal side elastic member 80 via grease G3. The first slinger side sliding surface 55 is an example of a slinger side sliding surface. Irregularities are formed on either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first slinger side sliding surface 55 of the slinger 50. On either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first slinger side sliding surface 55 of the slinger 50, no irregularities are formed on the other, and a smooth surface with a typical surface roughness is formed.

[0056] The second seal lip 84 of the seal lip 82 of the core metal side elastic member 80 has a second seal lip side sliding surface 88. The second seal lip side sliding surface 88 contacts the connection portion 53 of the slinger 50 via grease G4. The second seal lip side sliding surface 88 is an example of a seal lip side sliding surface. The connection portion 53 of the slinger 20 has a second slinger side sliding surface 56. The second slinger side sliding surface 56 contacts the second seal lip 84 of the seal lip 82 of the core metal side elastic member 80 via grease G4. The second slinger side sliding surface 56 is an example of a slinger side sliding surface. Irregularities are formed on either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second slinger side sliding surface 56 of the slinger 50. On either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second slinger side sliding surface 56 of the slinger 50, no irregularities are formed on the other, and a smooth surface with a typical surface roughness is formed.

[0057] As described above, irregularities are formed on either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first slinger side sliding surface 55 of the slinger 50. Also, irregularities are formed on either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second slinger side sliding surface 56 of the slinger 50. This configuration improves the interposition of grease G3 and G4 on the sliding surfaces (first seal lip side sliding surface 87, first slinger side sliding surface 55, second seal lip side sliding surface 88, and second slinger side sliding surface 56).

[0058] Furthermore, as described above, the thickeners of the outer seal member 10 grease G3 and G4 have a particle size distribution peak of 10 μm or less. By configuring the particle size of the thickeners of grease G3 and G4 to be relatively small in this way, the interception of grease G3 and G4 to the sliding surfaces (first seal lip side sliding surface 87, first slinger side sliding surface 55, second seal lip side sliding surface 88, and second slinger side sliding surface 56) can be improved, and an increase in surface pressure on the sliding surfaces can be suppressed. Therefore, even if the sliding surfaces are configured to have irregularities, wear of the seal lip 82 of the core metal side elastic member 80 that contacts the slinger 50 can be suppressed. Consequently, an increase in rotational torque due to wear of the seal lip 82 of the core metal side elastic member 80 can be prevented. In addition, a decrease in the tightening allowance of the seal lip 82 of the core metal side elastic member 80 and a decrease in mud-water resistance can be prevented due to wear of the seal lip 82 of the core metal side elastic member 80.

[0059] The surface roughness of the irregularities formed on either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first slinger side sliding surface 55 of the slinger 50 is 0.5 μmRa to 5.0 μmRa. Also, the surface roughness of the irregularities formed on either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second slinger side sliding surface 56 of the slinger 50 is 0.5 μmRa to 5.0 μmRa. By configuring it in this way, the interposition of grease G3 and G4 on the sliding surfaces (first seal lip side sliding surface 87, first slinger side sliding surface 55, second seal lip side sliding surface 88, and second slinger side sliding surface 56) can be further improved. Therefore, even if the sliding surface is configured to have irregularities, wear of the seal lip 82 of the core metal side elastic member 80 that contacts the slinger 50 can be suppressed. Consequently, it is possible to prevent an increase in rotational torque due to wear of the seal lip 82 of the core metal side elastic member 80. Furthermore, it is possible to prevent a decrease in mud-water resistance due to a reduction in the tightening allowance of the seal lip 82 of the core metal side elastic member 80 as a result of wear of the seal lip 82.

[0060] Furthermore, in order to further improve the interposition of grease G3 and G4, it is preferable that the surface roughness of the irregularities formed on either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first slinger side sliding surface 55 of the slinger 50 is greater than 3.0 μmRa and 5.0 μmRa or less. Furthermore, in order to further improve the interposition of grease G3 and G4, it is preferable that the surface roughness of the irregularities formed on either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second slinger side sliding surface 56 of the slinger 50 is greater than 3.0 μmRa and 5.0 μmRa or less.

[0061] Next, the wheel bearing device 1 shown in Figures 4 to 6 will be described. In describing the wheel bearing device 1 shown in Figures 4 to 6, the description of parts that are the same as those described in the wheel bearing device 1 shown in Figures 1 to 3 will be omitted as appropriate, and the description will focus on the parts that differ from the wheel bearing device 1 shown in Figures 1 to 3.

[0062] As shown in Figure 4, the wheel bearing device 1 has a configuration referred to as the third generation, and comprises an outer ring 2 which is an outer member, a hub ring 3 and an inner ring 4 which are inner members, two rows of inner ball rows 5 and outer ball rows 6 which are rolling rows, an inner sealing member 9 and an outer sealing member 10.

[0063] [Specific configuration of the inner sealing member] As shown in Figure 5, the inner sealing member 9 comprises a slinger 20, a core metal 30, and a core metal side elastic member 40.

[0064] The slinger 20 has an outer fitting portion 21, an annular portion 22, and an outer diameter portion 23. The annular portion 22 is equipped with a magnetic encoder 26. The magnetic encoder 26 is made of synthetic rubber or the like with magnetic poles (N pole and S pole) arranged in an annular shape. The magnetic encoder 26 is provided so as to cover the inner side surface of the annular portion 22 of the slinger 20, the outer diameter side surface of the outer fitting portion 21, and the outer end of the outer fitting portion 21. A predetermined space is formed between the magnetic encoder 26 and the base portion 41 of the core metal side elastic member 40. Note that the annular portion 22 may also be configured without the magnetic encoder 26.

[0065] The gap between the base 41 of the core metal elastic member 40 and the magnetic encoder 26 is configured as a labyrinth. By configuring the labyrinth in this way, foreign matter such as muddy water is prevented from entering between the slinger 20 and the core metal 30.

[0066] [Specific configuration of the outer sealing member] As shown in Figure 6, the outer sealing member 10 comprises a core metal 70 and a core metal side elastic member 80, but does not include a slinger 50 and a slinger side elastic member 60.

[0067] The core metal 70 is configured in a substantially annular shape and is fitted inside the outer ring 2. The core metal 70 is positioned such that a predetermined gap is formed between it and the hub ring 3 (base portion 3g of the hub ring), and the core metal 70 and the hub ring 3 are configured to be non-contact. The core metal 70 has a fitting portion 71 and an inner diameter portion 72.

[0068] The fitting portion 71 of the core metal 70 is cylindrical and fits onto the inner circumference of the outer end 2f of the outer ring 2. The fitting portion 71 is configured parallel to the axial direction. The inner diameter portion 72 is located on the inner diameter side of the fitting portion 71 and extends inward from the fitting portion 71. The outer diameter side end of the inner diameter portion 72 is connected to the inner side end of the fitting portion 71.

[0069] The core metal side elastic member 80 has a base portion 81 and a seal lip 82. The seal lip 82 prevents foreign matter such as muddy water from entering between the base portion 3g of the hub wheel 3 and the core metal 70. The seal lip 82 is provided on the base portion 81 and extends toward the base portion 3g of the hub wheel 3. The seal lip 82 comprises a first seal lip 83, a second seal lip 84, and a third seal lip 85.

[0070] The first seal lip 83 of the seal lip 82 prevents foreign matter such as muddy water from entering between the base 3g (axial surface 3i) of the hub wheel 3 and the mandrel 70. The first seal lip 83 extends from the inner diameter portion 72 of the mandrel 70 toward the axial surface 3i of the hub wheel 3. The first seal lip 83 extends toward the inner diameter and inner side and contacts the axial surface 3i of the hub wheel 3.

[0071] The second seal lip 84 of the seal lip 82 prevents foreign matter such as muddy water from entering between the base 3g (arc-shaped surface 3j) of the hub wheel 3 and the core metal 70. The second seal lip 84 extends from the inner diameter portion 72 of the core metal 70 toward the arc-shaped surface 3j of the hub wheel 3. The second seal lip 84 extends toward the outer side and contacts the inner side surface of the arc-shaped surface 3j of the hub wheel 3.

[0072] The third seal lip 85 of the seal lip 82 prevents foreign matter such as muddy water from entering between the base 3g (radial surface 3h) of the hub wheel 3 and the mandrel 70. The third seal lip 85 extends from the inner diameter portion 72 of the mandrel 70 toward the radial surface 3h of the hub wheel 3. The third seal lip 85 extends toward the outer side and contacts the radial surface 3h of the hub wheel 3.

[0073] The outer side seal member 10 is equipped with greases G3, G4, and G5. Greases G3, G4, and G5 are filled between the seal lip 82 of the core metal side elastic member 80 and the base portion 3g of the hub ring 3. Greases G3, G4, and G5 are bearing greases and contain a base oil and a thickener. The base oil kinematic viscosity of greases G3, G4, and G5 at 40°C is 65 mm² / S. The thickener of greases G3, G4, and G5 is, for example, a urea-based thickener. The thickener of greases G3, G4, and G5 has a particle size distribution peak of 10 μm or less (see Figure 7), and is composed of relatively small particles.

[0074] The first seal lip 83 of the seal lip 82 of the core metal side elastic member 80 has a first seal lip side sliding surface 87. The first seal lip side sliding surface 87 contacts the axial surface 3i of the hub wheel 3 via grease G3. The axial surface 3i of the hub wheel 3 has a first inner member side sliding surface 3l. The first inner member side sliding surface 3l contacts the first seal lip 83 of the seal lip 82 of the core metal side elastic member 80 via grease G3. The first inner member side sliding surface 3l is an example of an inner member side sliding surface. Irregularities are formed on either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first inner member side sliding surface 3l of the hub wheel 3. On either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first inner member side sliding surface 3l of the hub wheel 3, no irregularities are formed, and a smooth surface with a typical surface roughness is formed.

[0075] The second seal lip 84 of the seal lip 82 of the core metal side elastic member 80 has a second seal lip side sliding surface 88. The second seal lip side sliding surface 88 contacts the arc-shaped surface 3j of the hub wheel 3 via grease G4. The arc-shaped surface 3j of the hub wheel 3 has a second inner member side sliding surface 3m. The second inner member side sliding surface 3m contacts the second seal lip 84 of the seal lip 82 of the core metal side elastic member 80 via grease G4. The second inner member side sliding surface 3m is an example of an inner member side sliding surface. Irregularities are formed on either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second inner member side sliding surface 3m of the hub wheel 3. On either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second inner member side sliding surface 3m of the hub wheel 3, no irregularities are formed on the other, and a smooth surface with a typical surface roughness is formed.

[0076] The third seal lip 85 of the seal lip 82 of the core metal side elastic member 80 has a third seal lip side sliding surface 89. The third seal lip side sliding surface 89 contacts the radial surface 3h of the hub wheel 3 via grease G5. The third seal lip side sliding surface 89 is an example of a seal lip side sliding surface. The radial surface 3h of the hub wheel 3 has a third inner member side sliding surface 3n. The third inner member side sliding surface 3n contacts the third seal lip 85 of the seal lip 82 of the core metal side elastic member 80 via grease G5. The third inner member side sliding surface 3n is an example of an inner member side sliding surface. Irregularities are formed on either the third seal lip side sliding surface 89 of the seal lip 82 of the core metal side elastic member 80 or the third inner member side sliding surface 3n of the hub wheel 3. On either the third seal lip side sliding surface 89 of the seal lip 82 of the core metal side elastic member 80 or the third inner member side sliding surface 3n of the hub wheel 3, no irregularities are formed, and a smooth surface with a typical surface roughness is formed.

[0077] As described above, irregularities are formed on either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first inner member side sliding surface 3l of the hub wheel 3. Also, irregularities are formed on either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second inner member side sliding surface 3m of the hub wheel 3. Furthermore, irregularities are formed on either the third seal lip side sliding surface 89 of the seal lip 82 of the core metal side elastic member 80 or the third inner member side sliding surface 3n of the hub wheel 3. This configuration improves the interposition of greases G3, G4, and G5 on the sliding surfaces (first seal lip side sliding surface 87, first inner member side sliding surface 3l, second seal lip side sliding surface 88, second inner member side sliding surface 3m, third seal lip side sliding surface 89, and third inner member side sliding surface 3n).

[0078] Furthermore, as described above, the particle size distribution peaks of the thickeners in greases G3, G4, and G5 are 10 μm or less. By configuring the particle size of the thickeners in greases G3, G4, and G5 to be relatively small in this way, the interposition of greases G3, G4, and G5 to the sliding surfaces (first seal lip side sliding surface 87, first inner member side sliding surface 3l, second seal lip side sliding surface 88, second inner member side sliding surface 3m, third seal lip side sliding surface 89, and third inner member side sliding surface 3n) can be improved, thereby suppressing an increase in surface pressure on the sliding surfaces. For this reason, even if the sliding surfaces are configured to have irregularities, wear of the seal lip 82 of the core metal side elastic member 80 that contacts the hub wheel 3 can be suppressed. Consequently, an increase in rotational torque due to wear of the seal lip 82 of the core metal side elastic member 80 can be prevented. Furthermore, wear on the seal lip 82 of the core metal side elastic member 80 can reduce the tightening allowance of the seal lip 82 of the core metal side elastic member 80, thereby preventing a decrease in mud-water resistance.

[0079] The surface roughness of the irregularities formed on either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first inner member side sliding surface 3l of the hub wheel 3 is 0.5 μmRa to 5.0 μmRa. Also, the surface roughness of the irregularities formed on either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second inner member side sliding surface 3m of the hub wheel 3 is 0.5 μmRa to 5.0 μmRa. The surface roughness of the irregularities formed on either the third seal lip side sliding surface 89 of the seal lip 82 of the core metal side elastic member 80 or the third inner member side sliding surface 3n of the hub wheel 3 is 0.5 μmRa to 5.0 μmRa. This configuration improves the interposition of greases G3, G4, and G5 on the sliding surfaces (first seal lip side sliding surface 87, first inner member side sliding surface 3l, second seal lip side sliding surface 88, second inner member side sliding surface 3m, third seal lip side sliding surface 89, and third inner member side sliding surface 3n). Therefore, even with a configuration in which irregularities are formed on the sliding surfaces, wear of the seal lip 82 of the core metal side elastic member 80 that contacts the slinger 50 can be suppressed. Consequently, it is possible to prevent an increase in rotational torque due to wear of the seal lip 82 of the core metal side elastic member 80. Furthermore, it is possible to prevent a decrease in mud-water resistance due to a reduction in the tightening allowance of the seal lip 82 of the core metal side elastic member 80 as a result of wear of the seal lip 82 of the core metal side elastic member 80.

[0080] Furthermore, in order to further improve the interposition of greases G3, G4, and G5, it is preferable that the surface roughness of the irregularities formed on either the first seal lip side sliding surface 87 of the seal lip 82 of the core metal side elastic member 80 or the first inner member side sliding surface 3l of the hub wheel 3 is greater than 3.0 μmRa and 5.0 μmRa or less. Furthermore, in order to further improve the interposition of greases G3, G4, and G5, it is preferable that the surface roughness of the irregularities formed on either the second seal lip side sliding surface 88 of the seal lip 82 of the core metal side elastic member 80 or the second inner member side sliding surface 3m of the hub wheel 3 is greater than 3.0 μmRa and 5.0 μmRa or less. In order to further improve the interposition of greases G3, G4, and G5, it is preferable that the surface roughness of the irregularities formed on either the third seal lip side sliding surface 89 of the seal lip 82 of the core metal side elastic member 80 or the third inner member side sliding surface 3n of the hub wheel 3 is greater than 3.0 μmRa and less than or equal to 5.0 μmRa.

[0081] Although a wheel bearing device referred to as the third generation has been given as an example, the wheel bearing device according to the present invention is not limited to such a structure. For example, it may be a first-generation or second-generation structure in which a pair of inner rings are press-fitted into the small-diameter stepped portion of the hub ring, or a fourth-generation structure in which inner raceway surfaces are formed on the outer circumferential surfaces of the hub ring and the constant velocity universal joint, respectively, and these are used as inner members. Furthermore, although a double-row angular contact ball bearing with a row of balls as the rolling elements has been given as an example, it is not limited to this, and a double-row tapered roller bearing with tapered rollers as the rolling elements is also acceptable.

[0082] Although embodiments of the present invention have been described above, the present invention is not limited in any way to these embodiments, but is merely illustrative. It can be implemented in various other forms without departing from the spirit of the invention, and the scope of the present invention is indicated by the claims, and further includes all modifications within the meaning and scope of equivalents as described in the claims.

[0083] The present invention can be used in sealing devices and wheel bearing devices.

[0084] 1 Wheel bearing device 2 Outer ring 2a Inner side opening 2b Outer side opening 2c Outer raceway surface 2d Outer raceway surface 2e Inner side end 2d Outer side end 3 Hub ring 3a Small diameter step 3b Wheel mounting flange 3c Inner raceway surface 3e Bolt hole 3d Hub bolt 3e Inner raceway surface on the outer side 3f Flange side surface 3g Base 3h Radial surface 3i Axial surface 3j Arc-shaped surface 3k Outer diameter side surface 3l Sliding surface on the first inner member side 3m Sliding surface on the second inner member side 3n Sliding surface on the third inner member side 4 Inner ring 4a Inner side inner raceway surface 4b Inner side end 5 Inner side ball row 6 Outer side ball row 7 Ball 8 Cage 9 Inner side seal member 10 Outer side seal member 20 Slinger 21 51 Slinger 51 Fitting part 52 Ring part 53 Connecting part 54 Projection part 55 First slinger side sliding surface 56 Second slinger side sliding surface 60 Slinger side elastic member 70 Core metal 31 Fitting part 72 Inner diameter part 73 Ring part 74 Projection part 80 Core metal side elastic member 81 Base part 42 Seal lip 43 First seal lip 44 Second seal lip 45 Third seal lip 46 First seal lip side sliding surface 47 Second seal lip side sliding surface 50 Slinger 51 Fitting part 52 Ring part 53 Connecting part 54 Projection part 55 First slinger side sliding surface 56 Second slinger side sliding surface 60 Slinger side elastic member 70 Core metal 71 Fitting part 72 Inner diameter part 73 Ring part 74 Projection part 80 Core metal side elastic member 81 Base part 82 Seal lip 83 First seal lip 84 Second seal lip 85 Third seal lip 86 Weir section 87 Sliding surface on the first seal lip side 88 Sliding surface on the second seal lip side 89 Sliding surface on the third seal lip side

Claims

1. A sealing device for sealing an opening in the space between an outer member and an inner member of a wheel bearing device, comprising: a slinger fitted to the inner member; a core metal fitted to the outer member; an elastic member joined to the core metal and having a seal lip extending toward the slinger; and grease filled between the seal lip and the slinger, wherein the seal lip has a seal lip side sliding surface that contacts the slinger via the grease; the slinger has a slinger side sliding surface that contacts the seal lip via the grease; irregularities are formed on either the seal lip side sliding surface or the slinger side sliding surface; the grease contains a base oil and a thickener; and the thickener has a particle size distribution peak of 10 μm or less.

2. The sealing device according to claim 1, wherein the surface roughness of the irregularities formed on either the seal lip side sliding surface or the slinger side sliding surface is 0.5 μmRa to 5.0 μmRa.

3. A wheel bearing device comprising the sealing device described in claim 1, the wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces; and double rows of rolling elements rotatably housed between the raceway surfaces of the outer member and the inner member.

4. A wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces; double rows of rolling elements rotatably housed between the raceway surfaces of the outer member and the inner member; and a sealing device that closes the open end of an annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted into the outer member; an elastic member joined to the core metal and having a seal lip extending toward the inner member; and grease filled between the seal lip and the inner member, wherein the seal lip has a seal lip side sliding surface that contacts the inner member via the grease; the inner member has an inner member side sliding surface that contacts the seal lip via the grease; and irregularities are formed on either the seal lip side sliding surface or the inner member side sliding surface. The grease contains a base oil and a thickener, and the thickener has a particle size distribution peak of 10 μm or less, in a wheel bearing device.

5. The wheel bearing device according to claim 4, wherein the surface roughness of the irregularities formed on either the seal lip side sliding surface or the inner member side sliding surface is 0.5 μmRa to 5.0 μmRa.

Images