Hub unit bearing

Abstract

To provide a hub unit bearing in which deterioration of sealing performance and abrasion of a contact seal due to water stored at a radially inner end part of a flange inclined plane part can be easily suppressed.SOLUTION: A seal material 25 has at least one of seal clips 29a to 29c, a weir part 30, a canopy lip 31, and a contact lip 32. The weir part 30 extends so as to radially-outwardly project from an outer peripheral surface at an axially outward end part of an outer ring 2, and has a disk-like shape. The canopy lip 31 axially-outwardly and radially-outwardly extends from a part of the weir part 30 positioned radially-outwardly away from a core metal 24, and has an end edge part P1 positioned radially-outwardly from an end edge part P2 of a flange inclined plane part 12 and proximally facing the end edge part P2. The contact lip 32 axially-outwardly and radially-outwardly extends from a part axially overlapped with the core metal 24, and has a tip part in a slide contact with a part positioned radially inward from the flange inclined plane part 12.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a hub unit bearing for rotatably supporting a wheel of an automobile relative to a suspension system. [Background technology]

[0002] An automobile wheel is rotatably supported by a hub unit bearing relative to a suspension. The hub unit bearing comprises an outer ring having a double row outer ring raceway on its inner circumferential surface, a hub having a double row inner ring raceway on its outer circumferential surface and a rotating flange protruding radially outward at a portion axially outer than the outer ring, and a plurality of rolling elements arranged to roll freely between the double row outer ring raceway and the double row inner ring raceway. The outer ring is supported and fixed to the suspension. A wheel of the wheel and a braking rotor are joined and fixed to the rotating flange of the hub.

[0003] With respect to the hub unit bearing, the axially outer side is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axially inner side is the center side in the width direction of the vehicle when assembled to the vehicle.

[0004] The hub unit bearing further includes a seal ring that closes an axially outer opening of the rolling element installation space that exists between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub. The seal ring prevents foreign matter such as muddy water from entering the rolling element installation space from the outside through the opening, and prevents lubricating grease from leaking from the rolling element installation space to the outside.

[0005] FIG. 6 shows an installation portion of a seal ring that closes the axially outer opening of the rolling element installation space in a conventional hub unit bearing described in JP 2016-89999 A.

[0006] In the hub unit bearing 100 shown in Figure 6, the seal ring 104 that closes the opening on the axially outer side (left side in Figure 6) of the rolling element installation space 103 that exists between the inner surface of the outer ring 101 and the outer surface of the hub 102 is provided with a core metal 105 and a sealing material 106.

[0007] The core metal 105 is configured in an overall circular ring shape, and is supported and fixed to the end portion on the outer side in the axial direction of the outer ring 101 .

[0008] The seal member 106 is configured in an overall circular ring shape, and is joined and fixed to the core metal 105. The seal member 106 includes three seal lips 107 to 109, a dam portion 110, an overhanging lip 111, and a contact lip 112.

[0009] The three seal lips 107 to 109 are provided on the radially inner portion of the seal material 106, and the tip portion of each is in sliding contact with the surface of a sliding contact ring 113 that is fixedly fitted onto the outside of the hub 102 over the entire circumference.

[0010] Weir portion 110 is provided on a radially outer portion of sealing material 106, and protrudes radially outward beyond the outer circumferential surface of the axially outer end portion of outer ring 101. Weir portion 110 has a disk portion 114 located axially outer than outer ring 101, and a cylindrical portion 115 that extends from a radially inner portion of disk portion 114 toward the axially inner side (the right side in FIG. 6) and is fitted onto the outer circumferential surface of the axially outer end portion of outer ring 101. That is, dam portion 110 has an L-shaped cross section.

[0011] The eaves lip 111 extends axially outward and radially outward from the radially outer end of the dam portion 110. The axially outer edge portion of the inner circumferential surface of the eaves lip 111 closely faces the axially inner surface of a rotating flange 116 provided on the hub 102. Specifically, the rotating flange 116 has a flange inclined surface portion 117 in the radially middle portion of the axially inner surface, which is inclined in the axially inward direction as it approaches the radially inner side. The axially outer edge portion of the inner circumferential surface of the eaves lip 111 closely faces the radially middle portion of the flange inclined surface portion 117 over the entire circumference.

[0012] The contact lip 112 is disposed radially inward of the eaves lip 111, and extends axially and radially outward from a portion that axially overlaps with a radially outer portion of the core metal 105. The tip of the contact lip 112 is in sliding contact with a portion of the axially inner surface of the rotating flange 116 adjacent to the radially inner side of the flange inclined surface portion 117 over the entire circumference.

[0013] While the vehicle is traveling, a rotating air current is generated around the outer ring 101 due to the rotation of the wheel and the braking rotor. Muddy water splashed up from the road surface is caught in the rotating air current and circulates in the form of water droplets around the outer ring 101. When the vehicle stops and the rotating air current subsides, the water droplets that have been circulating around the outer ring together with the rotating air current fall onto the outer peripheral surface of the outer ring 101 and the axially inner surface of the rotating flange 116 at the top of the hub unit bearing 100.

[0014] The dam portion 110 blocks water droplets that fall onto the outer peripheral surface of the outer ring 101 and flow axially outward along the outer peripheral surface, thereby preventing the water droplets from entering between the axially outer end face of the outer ring 101 and the axially inner surface of the rotating flange 116. The eaves lip 111 prevents muddy water splashed up from the road surface from directly entering between the axially outer end face of the outer ring 101 and the axially inner surface of the rotating flange 116. The contact lip 112 prevents water droplets that fall onto the axially inner surface of the rotating flange 116 and flow downward along the axially inner surface from passing between the axially outer end face of the outer ring 101 and the axially inner surface of the rotating flange 116. In other words, the dam portion 110, the eaves lip 111, and the contact lip 112 each improve the function of preventing foreign matter such as muddy water from entering the rolling element installation space 103 from the outside through an opening on the axially outer side of the rolling element installation space 103. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] JP 2016-89999 A Summary of the Invention [Problem to be solved by the invention]

[0016] The conventional structure described in JP 2016-89999 A leaves room for improvement in terms of ensuring the sealing performance and durability of the contact lip.

[0017] That is, at the connection between the flange inclined surface portion 117 and a portion of the axially inner surface of the rotating flange 116 located radially inside the flange inclined surface portion 117, there is a ridge portion 118, which is a sharp corner. For this reason, water droplets that fall onto the axially inner surface of the rotating flange 116 at the top of the hub unit bearing 100 and flow downward along the axially inner surface tend to accumulate at the radially inner end of the flange inclined surface portion 117 due to the influence of surface tension. Some of the accumulated water does not move in the circumferential direction, but forms large lumps and drips onto the sliding contact portion between the tip of the contact lip 112 and the axially inner surface of the rotating flange 116, and as a result, a force acts at the sliding contact portion to turn over the tip of the contact lip 112. In addition, the sliding contact portion tends to remain wet, accelerating wear of the contact lip 112.

[0018] In the conventional structure, due to vibrations caused by the engine or when getting on and off the vehicle, or vibrations caused by the movement of the center of gravity of the vehicle body after stopping, the weir portion 110 and the eaves lip 111 elastically swing back and forth so as to fall in the axial direction starting from the radially inner end of the weir portion 110, and as a result, if the axially outer edge portion of the inner peripheral surface of the eaves lip 111 intermittently comes into contact with the water accumulated at the radially inner end of the flange inclined surface portion 117, the water can be moved in the circumferential direction and the water can be prevented from forming a large mass. In other words, the water accumulated at the radially inner end of the flange inclined surface portion 117 can be prevented from forming a large mass and dripping onto the sliding contact portion between the tip of the contact lip 112 and the axially inner surface of the rotating flange 116.

[0019] However, in the conventional structure, since the dam portion 110 has an L-shaped cross section and is highly rigid, the phenomenon in which the dam portion 110 and the eaves lip 111 elastically swing back and forth so as to fall in the axial direction starting from the radially inner end of the dam portion 110 is unlikely to occur. Even if such elastic deformation occurs, the axially outer end edge of the inner circumferential surface of the eaves lip 111 is closely opposed to the radially middle portion of the flange inclined surface portion 117, and therefore the end edge cannot be brought into intermittent contact with the water accumulated at the radially inner end of the flange inclined surface portion 117.

[0020] An object of the present disclosure is to provide a hub unit bearing that can easily prevent deterioration of sealing performance and wear of contact seals caused by water accumulating at the radially inner end of a flange inclined surface portion. [Means for solving the problem]

[0021] A hub unit bearing according to one aspect of the present disclosure includes an outer ring, a hub, a plurality of rolling elements, and a seal ring.

[0022] The outer ring has a double row outer ring raceway on its inner circumferential surface.

[0023] The hub has a double row inner ring raceway on its outer circumferential surface, and has a rotating flange that protrudes radially outward at a portion located axially outward from the outer ring.

[0024] The plurality of rolling elements are disposed so as to roll freely between the double row outer ring raceways and the double row inner ring raceways.

[0025] The seal ring closes an axially outer opening of a rolling element installation space that exists between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub.

[0026] The rotating flange has, at a radially intermediate portion of an axially inner surface, a flange inclined surface portion that is inclined inwardly in the axial direction as it extends radially inward.

[0027] The seal ring includes a core metal supported on an axially outer end of the outer ring, and a seal material coupled to the core metal.

[0028] The seal member has at least one seal lip, a dam portion, an overhang lip, and a contact lip.

[0029] The at least one seal lip is disposed at a radially inner portion of the seal material, and a tip end of the seal lip can be in sliding contact with or closely facing a surface of a member that rotates relative to the outer ring, specifically, a surface of the hub or a sliding ring fixed to the hub.

[0030] The dam portion is disposed at a radially outer portion of the sealing material and protrudes radially outward beyond an outer peripheral surface of an axially outer end portion of the outer ring.

[0031] The eaves lip extends axially and radially outward from a portion of the dam portion located radially outward from the core metal, and has an axially outer edge portion of an inner circumferential surface located radially outward of and closely facing a radially inner edge portion of the flange inclined surface portion. The distance between the radially inner edge portion of the flange inclined surface portion and the axially outer edge portion of the inner circumferential surface of the eaves lip can be set narrow enough to allow the axially outer edge portion of the inner circumferential surface of the eaves lip to lightly contact the radially inner end portion of the flange inclined surface portion (a portion including the radially inner edge portion of the flange inclined surface portion) when the dam portion is elastically deformed so as to fall axially outward due to vibrations generated during use.

[0032] The contact lip is positioned radially inward of the eaves lip, extends axially and radially outward from the portion axially overlapping with the core bar, and has a tip portion that is in sliding contact with a portion of the axial inner surface of the rotating flange that is positioned radially inward of the flange inclined surface portion.

[0033] In a hub unit bearing according to one aspect of the present disclosure, the dam portion extends so as to protrude radially outward beyond an outer circumferential surface of an axially outer end of the outer ring, and has a disk shape.

[0034] In one embodiment of the hub unit bearing of the present disclosure, the dam portion has a constricted portion located radially between the core bar and the base end of the eaves lip, the constricted portion having a smaller axial thickness than the radially adjacent portion.

[0035] In this case, the dam portion can include a cylindrical portion that extends axially inward from a portion located radially inward from the constricted portion and is fitted onto the outer peripheral surface of the axially outer end portion of the outer ring.

[0036] In a hub unit bearing according to one aspect of the present disclosure, in an imaginary plane including the central axis of the hub, a radially inner end portion of the flange inclined surface portion (a portion including a radially inner edge portion of the flange inclined surface portion) is disposed at a position intersecting an imaginary line consisting of a moving trajectory of an axially outer edge portion of an inner peripheral surface of the eaves lip when the dam portion is elastically deformed and an extension line of the moving trajectory. Effect of the Invention

[0037] According to the hub unit bearing of one aspect of the present disclosure, a structure is provided that can easily prevent deterioration of sealing performance and wear of the contact seal due to water accumulating at the radially inner end of the flange inclined surface portion. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a cross-sectional view showing a hub unit bearing according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is an enlarged view of part A in FIG. [Diagram 3] FIG. 3 is an enlarged view of the upper part of FIG. [Figure 4] FIG. 4 is a view corresponding to FIG. 3 and illustrating a hub unit bearing according to a second embodiment of the present disclosure. [Diagram 5]FIG. 5 is a view corresponding to FIG. 3 and illustrating a hub unit bearing according to a third embodiment of the present disclosure. [Figure 6] FIG. 6 is a cross-sectional view showing a portion where a seal ring is installed in a conventional structure of a hub unit bearing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] [Example 1] A hub unit bearing according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 to 3. FIG.

[0040] The hub unit bearing of the present disclosure can be applied to hub unit bearings of various structures, but in this example, a case where it is applied to a hub unit bearing for a driving wheel will be described.

[0041] The hub unit bearing 1 of this example includes an outer ring 2, a hub 3, a plurality of rolling elements 4a, 4b, and a seal ring 5.

[0042] In the following description of the hub unit bearing 1, the axially outer side is the left side in FIG. 1, which is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axially inner side is the right side in FIG. 1, which is the center side in the width direction of the vehicle when assembled to the vehicle.

[0043] The outer ring 2 is made of a hard metal such as medium carbon steel. The outer ring 2 has double-row outer ring raceways 6a, 6b on its inner circumferential surface. Furthermore, the outer ring 2 has a stationary flange 7 that protrudes radially outward at an axially intermediate portion. The stationary flange 7 has support holes 8 that penetrate in the axial direction at multiple circumferential positions at the radially intermediate portion.

[0044] The outer ring 2 is supported and fixed to the suspension by a support bolt that is inserted through a through hole provided in the knuckle of the suspension and screwed into a support hole 8 in the stationary flange 7 from the inside in the axial direction, so that the outer ring 2 does not rotate even when the wheel rotates.

[0045] The hub 3 has double row inner ring raceways 9a, 9b on its outer circumferential surface, and has a rotating flange 10 that protrudes radially outward at a portion located axially outward from the outer ring 2. Furthermore, the hub 3 has a cylindrical pilot portion 11 at its axially outer end. The hub 3 is disposed radially inward from the outer ring 2 and coaxially therewith.

[0046] The rotating flange 10 has a flange inclined surface portion 12 at the radially middle portion of its axially inner surface, which is inclined axially inward as it moves radially inward. In this example, the flange inclined surface portion 12 has a concave arc-shaped cross section. However, when implementing the hub unit bearing of the present disclosure, the cross section of the flange inclined surface portion can also be linear.

[0047] In this example, the axially inner surface of the rotating flange 10 has, in a portion located radially inside the flange inclined surface portion 12, an inner inclined surface portion 13, a flat portion 14, and a curved surface portion 15, in that order from the radially outer side.

[0048] The inner inclined surface portion 13 bends radially inward from the axially inner end of the flange inclined surface portion 12, and is inclined in the axially inner direction as it moves radially inward. In the illustrated example, the cross-sectional shape of the inner inclined surface portion 13 is a concave arc shape, but the cross-sectional shape can also be a straight line. The flat surface portion 14 is formed of an annular flat surface extending radially inward from the radially inner end of the inner inclined surface portion 13. The curved surface portion 15 is inclined in a curved manner in the axially inner direction as it moves radially inward from the radially inner end of the flat surface portion 14, and has a concave arc cross-sectional shape. The axially inner end of the curved surface portion 15 is connected to the axially outer end of the cylindrical surface portion 16 arranged adjacent to the axially outer side of the axially outer inner ring raceway 9a.

[0049] In this example, the portion of the axially inner surface of the rotating flange 10 that is located radially outward from the flange inclined surface portion 12 has recesses 17 that are recessed axially outward at multiple locations that are equally spaced circumferentially.

[0050] In this example, the rotating flange 10 has mounting holes 18 penetrating in the axial direction at a portion located radially outward from the flange inclined surface portion 12 and at a plurality of locations spaced apart from the recessed portion 17 in the circumferential direction.

[0051] The braking rotor, such as a brake disc, and the wheel of the vehicle are joined and fixed to the rotating flange 10 by inserting the pilot portion 11 into a central hole provided in the center of each of them, and by screwing a hub bolt, which has passed through holes provided at multiple locations in the circumferential direction of each of the radially middle portions, into the mounting hole 18 of the rotating flange 10. The braking rotor and wheel can also be joined and fixed to the rotating flange 10 by screwing a hub nut onto the tip of a stud bolt that is press-fitted into the mounting hole of the rotating flange and passed through the through holes of the braking rotor and the wheel.

[0052] In this example, the hub 3 is formed by combining a hub ring 19 and an inner ring 20. An inner ring raceway 9a on the axially outer side is provided on the outer peripheral surface of the axially middle part of the hub ring 19. A rotating flange 10 and a pilot portion 11 are provided on the axially outer part of the hub ring 19. An inner ring raceway 9b on the axially inner side is provided on the outer peripheral surface of the inner ring 20. The inner ring 20 is fitted and fixed to the outside of the axially inner part of the hub ring 19. As the hub unit bearing 1 in this example is for a drive wheel, the hub ring 19 has a spline hole 21 in the radial center for spline engagement with a spline shaft part constituting a drive shaft member.

[0053] The hub unit bearing of the present disclosure can also be applied to a hub unit bearing provided with a crimping portion at the axially inner end of the hub wheel that presses against the axially inner surface of the inner ring, a hub unit bearing in which the axially outer inner ring raceway is provided on the outer peripheral surface of another inner ring fitted onto the hub wheel, and a hub unit bearing for a driven wheel that does not have a spline hole in the radial center.

[0054] The rolling elements 4a, 4b are arranged between the double row outer ring raceways 6a, 6b and the double row inner ring raceways 9a, 9b, with multiple rolling elements for each row, and are rollably held by cages 22a, 22b arranged in each row. As a result, the hub 3 is supported rotatably on the radial inside of the outer ring 2.

[0055] In this example, tapered rollers are used as the rolling elements 4a, 4b, but balls can also be used as the rolling elements. In this example, the pitch circle diameter of the rolling elements 4a in the axially outer row and the pitch circle diameter of the rolling elements 4b in the axially inner row are set to be the same. However, the hub unit bearing of the present disclosure can also be applied to a different diameter PCD type hub unit bearing in which the pitch circle diameter of the rolling elements in the axially inner row and the pitch circle diameter of the rolling elements in the axially outer row are different from each other.

[0056] The seal ring 5 closes the opening on the axial outside of the rolling element installation space 23 that exists between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3. This prevents foreign matter such as muddy water from entering the rolling element installation space 23 from the outside through the opening, and prevents the lubricating grease sealed in the rolling element installation space 23 from leaking to the outside.

[0057] The seal ring 5 comprises a core metal 24 supported on the axially outer end of the outer ring 2 and a seal material 25 joined to the core metal 24 .

[0058] The core metal 24 is formed into an annular shape by bending a metal plate such as a mild steel plate. In this example, the core metal 24 includes a fitting tubular portion 26 that is tightly fitted into the axially outer end of the outer ring 2, an outward flange portion 27 that is bent radially outward from the axially outer end of the fitting tubular portion 26 and extends radially outward along the axially outer end face of the outer ring 2, and a support plate portion 28 that is folded back radially inward in a U-shape from the axially inner end of the fitting tubular portion 26 and has an axially outer end that extends radially inward. The radially outer end of the outward flange portion 27 protrudes radially outward beyond the axially outer end of the outer ring 2.

[0059] The seal material 25 is made of an elastic material containing an elastomer such as rubber, and is generally annular, and is bonded to the surface of the core metal 24 by vulcanization adhesion. In this example, the seal material 25 covers, among the surfaces of the core metal 24, the axial inner side, outer side, and axial outer side of the outward flange portion 27, the inner circumferential surface of the fitting tubular portion 26, the outer circumferential surface of the radial outer part of the support plate portion 28, and the axial outer side, inner circumferential surface, and radial inner end of the axial inner side of the radial inner part of the support plate portion 28. In this example, the axial inner side of the outward flange portion 27 is abutted against the axial outer end face of the outer ring 2 via a part of the seal material 25. This provides a seal between the axial inner side of the outward flange portion 27 and the axial outer end face of the outer ring 2.

[0060] The seal material 25 has at least one seal lip 29a, 29b, 29c, a dam portion 30, an eaves lip 31, and a contact lip 32. In this example, the seal material 25 has three seal lips 29a, 29b, 29c. However, when implementing the hub unit bearing of the present disclosure, the number of seal lips can be less than or more than three.

[0061] The three seal lips 29a, 29b, and 29c are disposed on the radially inner side of the seal material 25. The three seal lips 29a, 29b, and 29c have their respective tip portions in sliding contact with a member that rotates relative to the outer ring 2, specifically, the surface of the hub 3 in this example. The three seal lips 29a, 29b, and 29c are disposed in the order of the first seal lip 29a, the second seal lip 29b, and the third seal lip 29c from the side closer to the rolling element installation space 23. The first seal lip 29a extends radially inward and axially inward, and its tip portion is in sliding contact with the cylindrical surface portion 16 over the entire circumference. The second seal lip 29b extends axially outward and radially outward, and its tip portion is in sliding contact with the curved surface portion 15 over the entire circumference. The third seal lip 29c extends axially outward and radially outward, and has a tip portion in sliding contact with the flat portion 14 over the entire circumference.

[0062] When implementing the hub unit bearing of the present disclosure, the tip of the seal lip can be brought into sliding contact with the surface of a sliding ring fixed to the hub. When implementing the hub unit bearing of the present disclosure, the tip of at least one of the seal lips can be brought close to and opposite the surface of the hub or sliding ring, which are members that rotate relatively to the outer ring.

[0063] The dam portion 30 is disposed at a radially outer portion of the seal material 25, extends so as to protrude radially outward beyond the outer circumferential surface of the axially outer end portion of the outer ring 2, and has a disk shape.

[0064] While the vehicle is traveling, a rotating air current is generated around the outer ring 2 due to the rotation of the wheel and the braking rotor. Muddy water splashed up from the road surface is caught up in the rotating air current and circulates around the outer ring 2 in the form of water droplets. When the vehicle stops and the rotating air current subsides, the water droplets that have been circulating around the outer ring 2 with the rotating air current fall onto the outer peripheral surface of the outer ring 2 and the axially inner surface of the rotating flange 10 at the top of the hub unit bearing 1. The dam portion 30 blocks water droplets that fall onto the outer peripheral surface of the outer ring 2 and flow axially outward along the outer peripheral surface, thereby preventing the water droplets from entering between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 10.

[0065] In this example, the dam portion 30 has a disk shape. That is, unlike the dam portion 110 of the conventional structure (see FIG. 6), the dam portion 30 does not have a cylindrical portion at its radially inner portion that is fitted onto the axially outer end of the outer ring 2. For this reason, the dam portion 30 is easily flexibly and elastically deformed. Also, in this example, the axial thickness of the dam portion 30 is smaller than that of the dam portion 110 of the conventional structure (see FIG. 6). In this respect as well, the dam portion 30 is easily flexibly and elastically deformed.

[0066] In this example, the radially outer end of the outward flange 27 is covered by the radially inner portion of the dam portion 30, in other words, the radially inner portion of the dam portion 30 is reinforced by the radially outer end of the outward flange 27. When implementing the hub unit bearing of the present disclosure, a configuration can also be employed in which the radially outer end of the outward flange does not protrude radially outward beyond the outer peripheral surface of the axially outer end of the outer ring, and is not covered by the radially inner portion of the dam portion.

[0067] In any case, in this example, the dam portion 30 has a disk shape and is more flexible and elastically deformable than the dam portion 110 of the conventional structure. Specifically, the dam portion 30 is more likely to elastically swing back and forth so as to fall in the axial direction as shown by the two-dot chain line in Fig. 3 due to vibrations from the engine or when getting on and off the vehicle, and vibrations caused by the movement of the center of gravity of the vehicle body after stopping. More specifically, the dam portion 30 is more likely to elastically swing back and forth so as to fall in the axial direction, starting from the radially inner end of the portion of the dam portion 30 located radially outward from the outward flange portion 27.

[0068] The eaves lip 31 extends axially and radially outward from a portion of the dam portion 30 that is located radially outwardly relative to the outward flange portion 27 of the core metal 24. In this example, the base end of the eaves lip 31 is connected to a radially intermediate portion of the dam portion 30. When implementing the hub unit bearing of the present disclosure, the base end of the eaves lip can also be connected to a radially outer end of the dam portion.

[0069] An axially outer edge portion P1 of the inner peripheral surface of the eaves lip 31 is located radially outward of a radially inner edge portion P2 of the flange inclined surface portion 12 and closely faces said edge portion P2.

[0070] In this example, in the free state of the dam portion 30 and eaves lip 31 shown in Fig. 2, the axially outer edge P1 of the inner peripheral surface of the eaves lip 31 is located slightly axially outward (to the left in Fig. 2) than the radially inner edge P2 of the flange inclined surface portion 12, and the tip of the eaves lip 31 is disposed overlapping edge P2 in the radial direction. However, when implementing the hub unit bearing of the present disclosure, the axial positional relationship between edge P1 and edge P2 in the free state of the dam portion and eaves lip can be made different from this example.

[0071] In this example, the eaves lip 31 extends axially and radially outward from a portion of the dam portion 30 located radially outward from the outward flange portion 27 of the core metal 24, so that the eaves lip 31 can be elastically reciprocated together with the dam portion 30 so as to fall in the axial direction from a radially inner end of a portion of the dam portion 30 located radially outward from the outward flange portion 27 as a starting point due to vibrations of the engine or when getting on and off, and vibrations caused by the movement of the center of gravity of the vehicle body after stopping, as shown by a two-dot chain line in Fig. 3. In this example, in a virtual plane including the central axis of the hub 3, i.e., in the cross section shown in Fig. 3, when a virtual line consisting of a moving path of the axially outer edge portion P1 of the inner circumferential surface of the eaves lip 31 when the dam portion 30 is elastically deformed as described above and its extension line is defined as α, the radially inner end portion (the portion including the edge portion P2) of the flange inclined surface portion 12 is located at a position intersecting with the virtual line α.

[0072] The eaves lip 31 has the function of preventing muddy water splashed up from the road surface or water droplets falling from above from directly penetrating between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 10.

[0073] In this example, in the free state of the dam portion 30 and the eaves lip 31 shown in Fig. 2, the distance between the axially outer edge P1 of the inner peripheral surface of the eaves lip 31 and the radially inner edge P2 of the flange inclined surface portion 12 is narrowed to a level that allows the edge P1 to lightly contact the radially inner end of the flange inclined surface portion 12 when the dam portion 30 is elastically deformed so as to fall axially outward due to vibrations of the engine or when getting on and off, or vibrations due to the movement of the center of gravity of the vehicle body after stopping. Specifically, the distance between the edge P1 and the edge P2 can be, for example, 0.4 mm to 1.0 mm, and preferably 0.6 mm to 0.8 mm. In this example, the thickness of the eaves lip 31 is smaller than that of the eaves lip 111 of the conventional structure (see Fig. 6), and is easily elastically deformed flexibly.

[0074] In the structure of this example, a ridge portion 33, which is a pointed corner, is present at the connection portion between the flange inclined surface portion 12 and the inner inclined surface portion 13 on the axially inner surface of the rotating flange 10, i.e., at the radially inner edge portion P2 of the flange inclined surface portion 12. For this reason, water Wa that falls onto the axially inner surface of the rotating flange 10 at the top of the hub unit bearing 1 and flows downward along the axially inner surface is likely to accumulate at the radially inner end of the flange inclined surface portion 12 due to the influence of surface tension, as shown in Figure 3. Here, as in the conventional structure described above, if no external force is applied to the accumulated water Wa, some of the accumulated water Wa will not move in the circumferential direction, but will form a large lump and drip down onto the sliding contact portion between the tip of the contact lip 32 and the axially inner surface of the rotating flange 10.

[0075] In contrast, in this example, as described above, the eaves lip 31 can be elastically reciprocated together with the dam portion 30 so as to fall in the axial direction, starting from the radially inner end of the portion of the dam portion 30 located radially outward from the outward flange portion 27, as shown by the two-dot chain line in FIG. 3, due to vibrations caused by the engine or when getting on and off the vehicle, or vibrations caused by the movement of the center of gravity of the vehicle body after stopping. In addition, in this example, when such elastic deformation occurs, the distance between the end edge portion P1 and the end edge portion P2 is narrowed to a level that allows the end edge portion P1 to lightly contact the radially inner end of the flange inclined surface portion 12. Therefore, in this example, when the above-mentioned elastic deformation occurs, the axially outer end edge portion P1 of the inner peripheral surface of the eaves lip 31 can be intermittently brought into contact with the water Wa accumulated at the radially inner end of the flange inclined surface portion 12. This allows the water Wa to move in the circumferential direction, and prevents the water Wa from becoming a large mass. As a result, large lumps of water Wa can be prevented from dripping onto the sliding contact portion between the tip end of the contact lip 32 and the axially inner surface of the rotating flange 10.

[0076] In this example, the relative positions of the edge portions P1 and P2 are regulated so that the axially outer edge portion P1 of the inner peripheral surface of the eaves lip 31 is positioned axially outer (left side in FIG. 3) than the radially inner edge portion P2 of the flange inclined surface portion 12 in the entire range in which the dam portion 30 and the eaves lip 31 may elastically swing back and forth so as to fall in the axial direction, as shown by the two-dot chain line in FIG. 3. In other words, in the structure of this example, regardless of the occurrence of vibration, the edge portion P1 is always positioned axially outer than the edge portion P2, and the tip portion of the eaves lip 31 is maintained in a state in which it is radially overlapped with the edge portion P2. In this example, by adopting such a configuration, the function of the eaves lip 31 can always be performed well.

[0077] The contact lip 32 is disposed radially inward of the eaves lip 31, and extends axially and radially outward from a portion that axially overlaps with the outward flange portion 27 of the core bar 24. The tip of the contact lip 32 is in sliding contact with a portion of the axially inner surface of the rotating flange 10 that is located radially inward of the flange inclined surface portion 12, specifically the inner inclined surface portion 13, over the entire circumference.

[0078] The contact lip 32 prevents water droplets that fall onto the axially inner surface of the rotating flange 10 at the upper part of the hub unit bearing 1 and flow downward along the axially inner surface from passing between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 10.

[0079] When the water Wa (see FIG. 3) collected at the radially inner end of the flange inclined surface portion 12 becomes a large lump and drips onto the sliding contact portion between the tip of the contact lip 32 and the axially inner surface of the rotating flange 10, a force acts at the sliding contact portion to turn over the tip of the contact lip 32. In addition, the sliding contact portion is likely to remain wet, accelerating wear of the contact lip 32. In contrast, in the structure of this embodiment, as described above, the water Wa (see FIG. 3) collected at the radially inner end of the flange inclined surface portion 12 can be prevented from becoming a large lump and dripping onto the sliding contact portion between the tip of the contact lip 32 and the axially inner surface of the rotating flange 10, so that the sealing performance and durability of the contact lip 32 can be easily ensured. In other words, the hub unit bearing 1 of this embodiment makes it easy to prevent deterioration of the sealing performance and wear of the contact lip 32 caused by the water Wa collected at the radially inner end of the flange inclined surface portion 12.

[0080] In the structure of this example, within an imaginary plane including the central axis of the hub 3, the axially outer edge P3 of the outer circumferential surface of the contact lip 32 is disposed at a radial position where the tangent L of the radially inner edge P2 of the flange inclined surface portion 12 passes, or at a radial position inside the tangent L. Therefore, when water Wa that has flowed down vigorously along the flange inclined surface portion 12 at the upper part of the hub unit bearing 1 splashes out in the direction of the tangent L from the radially inner edge P2 (ridge portion 33) of the flange inclined surface portion 12, the splashed water Wa can be transferred to the outer circumferential surface of the contact lip 32 without hitting the tip surface of the contact lip 32. Therefore, this action also makes it easy to ensure the sealing performance and durability of the contact lip 32.

[0081] In the structure of this example, the contact lip 32 extends axially and radially outward from a portion that axially overlaps with a radially outer portion of the outward flange portion 27 of the core metal 24. This makes it possible to prevent the contact lip 32 from elastically deforming in a direction in which it falls due to vibrations from the engine or when getting on and off the vehicle, or vibrations caused by a shift in the center of gravity of the vehicle body after it has stopped. This makes it possible to stabilize the interference of the sliding portion of the tip of the contact lip 32 against the axially inner surface of the rotating flange 10, i.e., to stabilize the sealing performance of the contact lip 32.

[0082] The hub unit bearing 1 of this example further includes a combination seal ring 34 (see FIG. 1) that closes the axially inner opening of the rolling element installation space 23. This prevents external foreign matter from entering the rolling element installation space 23 through the opening and prevents grease from leaking from the rolling element installation space 23 to the outside.

[0083] [Example 2] A hub unit bearing according to a second embodiment of the present disclosure will be described with reference to FIG.

[0084] In the seal ring 5a that constitutes the hub unit bearing of this example, the dam portion 30a has a constricted portion 35 that is smaller in axial thickness than the radially adjacent portion at a portion located radially between the outward flange portion 27 of the core metal 24 and the base end of the eaves lip 31.

[0085] Specifically, in this example, the constricted portion 35 is provided at a radially inner end of a portion of the dam portion 30a that is located radially outward from the outward flange portion 27. A circumferential groove 36 is provided in each of the portions of the dam portion 30a that are located on both axial sides of the constricted portion 35. However, one of the circumferential grooves 36 may be omitted.

[0086] In this example, a constricted portion 35 is provided at the radially inner end of the dam portion 30a located radially outward of the outward flange portion 27, thereby reducing the rigidity of the end. This makes it easier for the dam portion 30 and the eaves lip 31 to elastically swing back and forth so as to fall in the axial direction starting from the constricted portion 35 due to vibrations caused by the engine or when getting on and off the vehicle, or vibrations caused by the movement of the center of gravity of the vehicle body after stopping, and makes it easier for the axially outer edge portion P1 of the inner peripheral surface of the eaves lip 31 to intermittently come into contact with the water Wa accumulated at the radially inner end of the flange inclined surface portion 12. The other configurations and effects of the second example are similar to those of the first example.

[0087] [Example 3] A hub unit bearing according to a third embodiment of the present disclosure will be described with reference to FIG.

[0088] In the seal ring 5b constituting the hub unit bearing of this example, the dam portion 30b extends axially inward from a portion located radially inward from the constricted portion 35, and further includes a cylindrical portion 37 fitted onto the outer peripheral surface of the axially outer end portion of the outer ring 2. That is, the dam portion 30b of this example has an L-shaped cross section. The cylindrical portion 37 can be fitted onto the outer peripheral surface of the axially outer end portion of the outer ring 2 so as to have an interference fit.

[0089] In this example, the dam portion 30b includes a cylindrical portion 37 fitted onto the outer peripheral surface of the axially outer end portion of the outer ring 2, and therefore can more effectively prevent water droplets that have flowed axially outward along the outer peripheral surface of the outer ring 2 from entering between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 10. The other configurations and effects of the third example are similar to those of the second example. [Explanation of symbols]

[0090] 1 Hub unit bearing 2 Outer ring 3. Hub 4a, 4b Rolling elements 5, 5a, 5b Seal ring 6a, 6b Outer raceway 7 Stationary Flange 8 Support hole 9a, 9b Inner raceway 10 Rotating flange 11 Pilot Division 12 Flange inclined surface 13 Inner slope section 14 Plane part 15 Curved section 16 Cylindrical surface part 17 Recess 18 Mounting hole 19 Hub wheel 20. Inner Circle 21 Spline hole 22a, 22b retainer 23 Rolling element installation space 24 Core wire 25 Sealing material 26 Fitting cylinder part 27 Outward flange 28 Support plate part 29a, 29b, 29c Seal lip 30, 30a, 30b Weir 31 Eaves lip 32 Contact Lip 33 Ridge 34 Combination Seal Ring 35 Neck 36 Circumferential groove 37 Cylindrical section 100 Hub unit bearing 101 Outer ring 102 Hub 103 Rolling element installation space 104 Seal ring 105 Core 106 Sealing material 107 Seal lip 108 Seal Lip 109 Seal Lip 110 Weir 111 Eaves lip 112 Contact Lip 113 Sliding ring 114 Disc section 115 Cylindrical part 116 Rotating flange 117 Flange inclined surface 118 Ridge

Claims

1. an outer ring having a double row outer ring raceway on an inner circumferential surface; a hub having a double row inner ring raceway on an outer peripheral surface thereof and a rotating flange protruding radially outward at a portion located axially outwardly of the outer ring; a plurality of rolling elements disposed between the double row outer ring raceways and the double row inner ring raceways so as to be freely rollable; a seal ring that closes an axially outer opening of a rolling element installation space that exists between an inner peripheral surface of the outer ring and an outer peripheral surface of the hub; Equipped with the rotating flange has a flange inclined surface portion at a radially intermediate portion of an axially inner surface thereof, the flange inclined surface portion being inclined in a direction toward the axially inner side as it extends radially inward, the seal ring includes a core metal supported on an axially outer end portion of the outer ring, and a seal material coupled to the core metal, The sealing material has at least one seal lip, a dam portion, an overhanging lip, and a contact lip, The at least one seal lip is disposed on a radially inner portion of the seal material, the dam portion is disposed in a radially outer portion of the sealing material, extends so as to protrude radially outward beyond an outer circumferential surface of an axially outer end portion of the outer ring, and has a disk shape, the eaves lip extends axially outward and radially outward from a portion of the dam portion that is located radially outwardly with respect to the core metal, and has an axially outer edge portion of an inner circumferential surface that is located radially outwardly of a radially inner edge portion of the flange inclined surface portion and closely faces the radially inner edge portion, the contact lip is disposed radially inward of the eaves lip, extends axially and radially outward from a portion overlapping with the core bar in the axial direction, and has a tip portion that is in sliding contact with a portion of the axially inner surface of the rotating flange that is positioned radially inward relative to the flange inclined surface portion, Hub unit bearing.

2. an outer ring having a double row outer ring raceway on an inner circumferential surface; a hub having a double row inner ring raceway on an outer peripheral surface thereof and a rotating flange protruding radially outward at a portion located axially outwardly of the outer ring; a plurality of rolling elements disposed between the double row outer ring raceways and the double row inner ring raceways so as to be freely rollable; a seal ring that closes an axially outer opening of a rolling element installation space that exists between an inner peripheral surface of the outer ring and an outer peripheral surface of the hub; Equipped with the rotating flange has a flange inclined surface portion at a radially intermediate portion of an axially inner surface thereof, the flange inclined surface portion being inclined in a direction toward the axially inner side as it extends radially inward, the seal ring includes a core metal supported on an axially outer end portion of the outer ring, and a seal material coupled to the core metal, The sealing material has at least one seal lip, a dam portion, an overhanging lip, and a contact lip, The at least one seal lip is disposed on a radially inner portion of the seal material, the dam portion is disposed in a radially outer portion of the sealing material and protrudes radially outward beyond an outer circumferential surface of an axially outer end portion of the outer ring, the eaves lip extends axially outward and radially outward from a portion of the dam portion that is located radially outwardly with respect to the core metal, and has an axially outer edge portion of an inner circumferential surface that is located radially outwardly of a radially inner edge portion of the flange inclined surface portion and closely faces the radially inner edge portion, the contact lip is disposed radially inward of the eaves lip, extends axially and radially outward from a portion that axially overlaps with the core bar, and has a tip portion that is in sliding contact with a portion of the axially inner surface of the rotating flange that is positioned radially inward relative to the flange inclined surface portion, The dam portion has a constricted portion at a portion located between the core metal and the base end portion of the eaves lip in the radial direction, the constricted portion having an axial thickness smaller than that of a portion adjacent thereto in the radial direction. Hub unit bearing.

3. 3. The hub unit bearing according to claim 2, wherein the dam portion extends axially inward from a portion located radially inward from the constricted portion and includes a cylindrical portion fitted onto an outer peripheral surface of an axially outer end portion of the outer ring.

4. A hub unit bearing according to any one of claims 1 to 3, wherein, in an imaginary plane including a central axis of the hub, a radially inner end portion of the flange inclined surface portion is positioned at a position intersecting an imaginary line consisting of a movement trajectory of an axially outer end edge portion of the inner surface of the eaves lip when the dam portion is elastically deformed and an extension line of the movement trajectory.

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