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 vehicle wheel relative to a suspension device. [Background Art]

[0002] Wheels of an automobile are rotatably supported relative to a suspension device by hub unit bearings. A hub unit bearing includes: an outer ring having double-row outer raceways on an inner peripheral surface thereof; a hub having double-row inner raceways on an outer peripheral surface thereof, and a rotating flange protruding radially outward at a portion positioned axially outward of the outer ring; and a plurality of rolling elements rollably disposed between the double-row outer raceways and the double-row inner raceways. The outer ring is supported and fixed to the suspension device. A vehicle wheel and a braking rotating body are coupled and fixed to the rotating flange of the hub.

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

[0004] The hub unit bearing further includes a seal ring that blocks the axially outer opening of the rolling element installation space existing 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 out of the rolling element installation space to the outside.

[0005] Figure 6 shows an installation portion of a seal ring that blocks the axially outer opening of the rolling element installation space in a conventional hub unit bearing described in Japanese Patent Application Laid-Open No. 2016-89999.

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

[0007] The core metal 105 is configured in an annular shape and is supported and fixed to the axially outer end of the outer ring 101.

[0008] The sealing material 106 is constructed in an annular shape and is bonded and fixed to the core metal 105. The sealing material 106 comprises three sealing lips 107-109, a weir section 110, a canopy lip 111, and a contact lip 112.

[0009] The three seal lips 107-109 are located on the radially inner portion of the seal material 106, and the tip of each of them slides in contact with the surface of the sliding ring 113, which is fitted and fixed to the hub 102, over its entire circumference.

[0010] The weir portion 110 is provided on the radially outer portion of the sealing material 106 and protrudes radially outward from the outer circumferential surface of the axially outer end of the outer ring 101. The weir portion 110 has a disc portion 114 located axially outward from the outer ring 101 and a cylindrical portion 115 that extends axially inward (to the right in Figure 6) from the radially inner portion of the disc portion 114 and is fitted onto the outer circumferential surface of the axially outer end of the outer ring 101. In other words, the weir portion 110 has an L-shaped cross-section.

[0011] The canopy lip 111 extends from the radially outer end of the weir section 110 in an axially and radially outward direction. The axially outer edge of the inner circumferential surface of the canopy lip 111 is in close proximity to the axially inner surface of the rotating flange 116 provided on the hub 102. Specifically, the rotating flange 116 has a flange inclined surface portion 117 in the radially intermediate portion of its axially inner surface, which is inclined in a direction that increases axially inward as it extends radially inward. The axially outer edge of the inner circumferential surface of the canopy lip 111 is in close proximity to the radially intermediate portion of the flange inclined surface portion 117 over its entire circumference.

[0012] The contact lip 112 is positioned radially inward of the canopy lip 111 and extends axially and radially outward from the portion that overlaps axially with the radially outward portion of the core metal 105. The tip of the contact lip 112 slides around the entire circumference of the portion of the axially inward surface of the rotating flange 116 that is adjacent to the radially inward side of the flange inclined surface 117.

[0013] While the vehicle is in motion, a rotating airflow is generated around the outer ring 101 due to the rotation of the wheel and the braking rotating body. Mud splashed up from the road surface is taken up by this rotating airflow and circulates around the outer ring 101 in the form of water droplets. When the vehicle stops and the rotating airflow subsides, the water droplets that were circulating around the outer ring with the rotating airflow fall onto the outer circumferential 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 weir 110 prevents water droplets that fall onto the outer circumferential surface of the outer ring 101 and flow axially outward along that outer circumferential surface from entering the space between the axially outward end face of the outer ring 101 and the axially inward surface of the rotating flange 116 by blocking them. The canopy lip 111 prevents muddy water splashed up from the road surface from directly entering the space between the axially outward end face of the outer ring 101 and the axially inward surface of the rotating flange 116. The contact lip 112 prevents water droplets that fall onto the axially inward surface of the rotating flange 116 and flow downward along that axially inward surface from passing between the axially outward end face of the outer ring 101 and the axially inward surface of the rotating flange 116. In other words, the weir 110, canopy lip 111, and 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 the axially outward opening of the rolling element installation space 103. [Prior art documents] [Patent Documents]

[0015] [Patent Document 1] Japanese Patent Publication No. 2016-89999 [Overview of the Initiative] [Problems that the invention aims to solve]

[0016] The conventional structure described in Japanese Patent Publication No. 2016-89999 has room for improvement in terms of ensuring the sealing performance and durability of the contact lip.

[0017] In other words, a sharp corner, or ridge 118, exists at the connection point between the portion of the axial inner surface of the rotating flange 116 that is radially inward from the flange inclined surface portion 117 and the flange inclined surface portion 117. Therefore, water droplets that fall onto the axial inner surface of the rotating flange 116 at the top of the hub unit bearing 100 and flow downward along this axial inner surface tend to accumulate at the radially inward end of the flange inclined surface portion 117 due to surface tension. Some of the accumulated water does not move circumferentially but forms large clumps that drip onto the sliding contact area between the tip of the contact lip 112 and the axial inner surface of the rotating flange 116. As a result, a force acts at the sliding contact area that tries to peel back the tip of the contact lip 112. Furthermore, the sliding contact area tends to remain wet, accelerating the wear of the contact lip 112.

[0018] In the conventional structure, vibrations from the engine, during boarding and alighting, and vibrations due to the shift in the vehicle's center of gravity after stopping cause the weir section 110 and the canopy lip 111 to elastically reciprocate and oscillate, tilting axially from the radially inner end of the weir section 110. As a result, if the axially outer edge of the inner circumferential surface of the canopy lip 111 intermittently contacts the water accumulated at the radially inner end of the flange inclined surface 117, the water is moved circumferentially, preventing it from forming large clumps. In other words, it is possible to prevent the water accumulated at the radially inner end of the flange inclined surface 117 from forming large clumps and dripping onto the sliding contact area 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 weir portion 110 has an L-shaped cross-sectional shape and the weir portion 110 has high rigidity, a phenomenon in which the weir portion 110 and the eaves lip 111 elastically reciprocate and swing so as to fall axially starting from the radially inner end of the weir portion 110 is unlikely to occur. Further, even if such elastic deformation occurs, the axially outer edge portion of the inner peripheral surface of the eaves lip 111 is closely opposed to the radially intermediate portion of the flange inclined surface portion 117, so that the edge portion cannot be intermittently brought into contact with 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 suppress deterioration of sealing performance and wear of a contact seal caused by water accumulated at a 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 double-row outer ring raceways on an inner peripheral surface thereof.

[0023] The hub has double-row inner ring raceways on an outer peripheral surface thereof, and has a rotating flange protruding radially outward at a portion located axially outer than the outer ring.

[0024] The plurality of rolling elements are rollably disposed 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 existing 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 side surface thereof, a flange inclined surface portion inclined in a direction toward an axially inner side as going toward a radially inner side.

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

[0028] The sealing material includes at least one seal lip, a dam portion, a shelter lip, and a contact lip.

[0029] The at least one seal lip is disposed on a radially inner portion of the sealing material. A tip end portion of the seal lip can be brought into sliding contact or closely opposed to a surface of a member that rotates relative to the outer ring, specifically, a surface of the hub or a sliding contact ring fixed to the hub.

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

[0031] The shelter lip extends axially outward and radially outward from a portion of the dam portion that is spaced radially outward from the core metal, and has an axially outer end edge of an inner peripheral surface that is positioned radially outward from a radially inner end edge of the flange inclined surface portion and closely opposed to the radially inner end edge. A gap between the radially inner end edge of the flange inclined surface portion and the axially outer end edge of the inner peripheral surface of the shelter lip can be set narrow enough to allow the axially outer end edge of the inner peripheral surface of the shelter lip to lightly contact a radially inner end portion (including the radially inner end edge) of the flange inclined surface portion when the dam portion is elastically deformed to fall axially outward due to vibration generated during use.

[0032] The contact lip is disposed radially inward of the shelter lip, extends axially outward and radially outward from a portion axially overlapping the core metal, and has a tip end portion that is in sliding contact with a portion of an axially inner side surface of the rotating flange positioned radially inward of the flange inclined surface portion.

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

[0034] In one embodiment of the present disclosure, the weir portion has a constricted portion in which the axial thickness is smaller than that of the radially adjacent portion, in the portion located radially between the core metal and the base end of the canopy lip.

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

[0036] In a hub unit bearing according to one aspect of the present disclosure, in a virtual plane including the central axis of the hub, the radially inner end of the flange inclined surface (including the radially inner edge of the flange inclined surface) is positioned at a location where it intersects with a virtual line formed by the movement trajectory of the axially outer edge of the inner circumferential surface of the canopy lip when the weir is elastically deformed, and its extension. 。 [Effects of the Invention]

[0037] According to one aspect of the present disclosure, a hub unit bearing is provided that makes it easier to suppress deterioration of sealing performance and wear of the contact seal due to water accumulating at the radially inner end of the flange inclined surface. [Brief explanation of the drawing]

[0038] [Figure 1] Figure 1 is a cross-sectional view showing a hub unit bearing of a first example of an embodiment of the present disclosure. [Figure 2] Figure 2 is an enlarged view of section A in Figure 1. [Figure 3] Figure 3 is an enlarged view of the upper part of Figure 2. [Figure 4] Figure 4 is a diagram corresponding to Figure 3, showing a hub unit bearing of a second example of the embodiment of the present disclosure. [Figure 5]Figure 5 is a diagram corresponding to Figure 3 for a hub unit bearing of a third example of the embodiment of this disclosure. [Figure 6] Figure 6 is a cross-sectional view showing the installation portion of the seal ring in a conventional hub unit bearing structure. [Modes for carrying out the invention]

[0039] [Example 1] A hub unit bearing of a first example of the embodiment of this disclosure will be described with reference to Figures 1 to 3.

[0040] The hub unit bearings of this disclosure are applicable to hub unit bearings of various structures, but this example will describe their application to hub unit bearings for drive wheels.

[0041] The hub unit bearing 1 in this example comprises 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 axial outer side is the left side of Figure 1, which is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axial inner side is the right side of Figure 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 rows of outer ring raceways 6a and 6b on its inner circumferential surface. Furthermore, the outer ring 2 has a stationary flange 7 projecting radially outward in its axial middle section. The stationary flange 7 has support holes 8 that penetrate axially at multiple locations in the circumferential direction in its radial middle section.

[0044] The outer ring 2 is supported and fixed to the suspension system by screwing support bolts, which are inserted through holes provided in the knuckle of the suspension system, into support holes 8 of the stationary flange 7 from the axial inside, and does not rotate even when the wheel rotates.

[0045] The hub 3 has double rows of inner ring raceways 9a and 9b on its outer circumference, and a rotating flange 10 that protrudes radially outward in a portion located axially outward from the outer ring 2. Furthermore, the hub 3 has a cylindrical pilot portion 11 at its axially outward end. The hub 3 is positioned radially inward from the outer ring 2 and coaxially with the outer ring 2.

[0046] The rotating flange 10 has a flange inclined surface portion 12 in the radially intermediate portion of its axially inner surface, which is inclined in a direction that increases inward in the axial direction as it extends 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 this disclosure, the cross-sectional shape of the flange inclined surface portion can also be linear.

[0047] In this example, the axial inner surface of the rotating flange 10 has 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 inward end of the flange inclined surface portion 12 and inclins axially inward as it extends radially inward. In the illustrated example, the cross-sectional shape of the inner inclined surface portion 13 is a concave arc, but the cross-sectional shape can also be a straight line. The flat portion 14 is composed of an annular plane extending radially inward from the radially inward end of the inner inclined surface portion 13. The curved surface portion 15 is curved inward as it extends radially inward from the radially inward end of the flat portion portion 14 and has a concave arc cross-sectional shape. The axially inward end of the curved surface portion 15 is connected to the axially outer end of the cylindrical surface portion 16, which is located adjacent to the axially outer side of the inner ring raceway 9a on the axially outer side.

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

[0050] In this example, the rotating flange 10 has mounting holes 18 that penetrate axially at multiple locations in the circumferential direction that are outside the recess 17, among the portions located radially outward from the flange inclined surface portion 12.

[0051] Brake discs and other braking rotating bodies and wheels are joined and fixed to the rotating flange 10 by inserting pilot portions 11 through central holes provided in the center of each and screwing hub bolts, which are inserted through through holes provided at multiple locations in the circumferential direction in the radial middle of each, into mounting holes 18 of the rotating flange 10. Alternatively, the braking rotating bodies and wheels can also be joined and fixed to the rotating flange 10 by pressing stud bolts into the mounting holes of the rotating flange, inserting them through the through holes of the braking rotating bodies and wheels, and then screwing hub nuts onto the tips of the studs.

[0052] In this example, the hub 3 is formed by combining a hub ring 19 and an inner ring 20. The axially outer inner ring raceway 9a is provided on the outer circumferential surface of the axially intermediate portion of the hub ring 19. The rotating flange 10 and pilot portion 11 are provided on the axially outer portion of the hub ring 19. The axially inner inner ring raceway 9b is provided on the outer circumferential surface of the inner ring 20. The inner ring 20 is externally fitted and fixed to the axially inner portion of the hub ring 19. Since the hub unit bearing 1 in this example is for a drive wheel, the hub ring 19 has a spline hole 21 in its radially central portion for spline engaging the spline shaft portion constituting the drive shaft member.

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

[0054] Multiple rolling elements 4a and 4b are arranged in each row between the double-row outer ring raceways 6a and 6b and the double-row inner ring raceways 9a and 9b, and are held in place by cages 22a and 22b located in each row so as to be able to roll. As a result, the hub 3 is rotatably supported radially inward of the outer ring 2.

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

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

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

[0058] The core metal 24 is formed into an annular shape by bending a metal plate such as mild steel. In this example, the core metal 24 includes a fitting cylinder portion 26 that is fitted and fixed to the axially outer end of the outer ring 2 by interference fit, an outward-facing flange portion 27 that bends radially outward from the axially outer end of the fitting cylinder 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 cylinder portion 26, with the axially outer end extending radially inward. The radially outer end of the outward-facing flange portion 27 protrudes radially outward more than the axially outer end of the outer ring 2.

[0059] The sealing material 25 is made of an elastic material containing an elastomer such as rubber, and is formed in an annular shape, and is bonded to the surface of the core metal 24 by vulcanization adhesion. In this example, the sealing material 25 covers the axial inner surface, outer surface, and axial outer surface of the outward-facing flange portion 27, the inner surface of the fitting cylinder portion 26, the outer surface of the radially outer part of the support plate portion 28, and the radially inner ends of the axial outer surface, inner surface, and axial inner surface of the radially inner part of the support plate portion 28. In this example, the axial inner surface of the outward-facing flange portion 27 is brought into contact with the axially outer end surface of the outer ring 2 via a portion of the sealing material 25. This seals the space between the axial inner surface of the outward-facing flange portion 27 and the axially outer end surface of the outer ring 2.

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

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

[0062] When implementing the hub unit bearing of this disclosure, the tip of the seal lip may be brought into sliding contact with the surface of the sliding ring fixed to the hub. When implementing the hub unit bearing of this disclosure, the tip of at least one of the seal lips may be brought into close proximity to the surface of the hub or sliding ring, which are members that rotate relative to the outer ring.

[0063] The weir portion 30 is positioned on the radially outer portion of the sealing material 25, extends radially outward beyond the outer circumferential surface of the axially outer end of the outer ring 2, and has a disc shape.

[0064] While the vehicle is in motion, a rotating airflow is generated around the outer ring 2 due to the rotation of the wheel and the braking rotating body. Mud splashed up from the road surface is taken up by this rotating airflow and circulates around the outer ring 2 in the form of water droplets. When the vehicle stops and the rotating airflow subsides, the water droplets that were circulating around the outer ring 2 with the rotating airflow fall onto the outer circumferential 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 weir 30 prevents the water droplets that have fallen onto the outer circumferential surface of the outer ring 2 and flowed axially outward along the outer circumferential surface from entering the space between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 10 by blocking them.

[0065] In this example, the weir section 30 has a disc shape. That is, unlike the conventional weir section 110 (see Figure 6), the weir section 30 does not have a cylindrical portion on its radially inner side that is fitted onto the axially outer end of the outer ring 2. Therefore, the weir section 30 is easily elastically deformable. Also, in this example, the axial thickness of the weir section 30 is smaller than that of the conventional weir section 110 (see Figure 6). In this respect as well, the weir section 30 is easily elastically deformable.

[0066] In this example, the radially inner portion of the weir 30 covers the radially outer end of the outward flange 27; in other words, the radially inner portion of the weir 30 is reinforced by the radially outer end of the outward flange 27. When implementing the hub unit bearing of this disclosure, a configuration can also be adopted 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 weir.

[0067] In any case, in this example, the weir section 30 has a disc shape and is more flexible and elastically deformable than the conventional weir section 110. Specifically, due to vibrations from the engine, when getting on and off the vehicle, and vibrations due to the shift in the vehicle's center of gravity after stopping, the weir section 30 is prone to elastically reciprocating and tilting in the axial direction, as shown by the dashed line in Figure 3. More specifically, the weir section 30 is prone to elastically reciprocating and tilting in the axial direction, starting from the radially inner end of the portion of the weir section 30 located radially outward from the outward flange section 27.

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

[0069] The axially outer edge P1 of the inner circumferential surface of the canopy lip 31 is located radially outward from the radially inner edge P2 of the flange inclined surface 12, and is in close proximity to and facing the edge P2.

[0070] In this example, in the free state of the weir portion 30 and the canopy lip 31 shown in Figure 2, the axially outer edge P1 of the inner circumferential surface of the canopy lip 31 is located slightly axially outward (to the left in Figure 2) than the radially inner edge P2 of the flange inclined surface portion 12, and the tip of the canopy lip 31 is positioned to overlap radially with the edge P2. However, when implementing the hub unit bearing of this disclosure, the axial positional relationship between the edge P1 and the edge P2 in the free state of the weir portion and the canopy lip can be made different from that in this example.

[0071] In this example, the canopy lip 31 extends axially and radially outward from a portion of the weir 30 that is located radially outward from the outward flange portion 27 of the core metal 24. Therefore, vibrations from the engine, when getting in and out of the vehicle, and vibrations due to the shift in the center of gravity of the vehicle body after stopping can cause the canopy lip 31 to reciprocate elastically, as shown by the dashed line in Figure 3, starting from the radially inward end of the portion of the weir 30 that is located radially outward from the outward flange portion 27. In this example, in a virtual plane containing the central axis of the hub 3, i.e., the cross-section shown in Figure 3, if we define α as a virtual line consisting of the movement trajectory of the axially outward edge portion P1 of the inner circumferential surface of the canopy lip 31 when the weir 30 is elastically deformed as described above, and its extension, then the radially inward end of the flange inclined surface portion 12 (the portion including the edge portion P2) is positioned to intersect with the virtual line α.

[0072] The canopy lip 31 has the function of preventing mud and water splashed up from the road surface or water droplets falling from above from directly entering the space 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 weir section 30 and canopy lip 31 shown in Figure 2, the distance between the axially outer edge P1 of the inner circumferential surface of the canopy lip 31 and the radially inner edge P2 of the flange inclined surface 12 is narrowed to a level that allows the edge P1 to lightly contact the radially inner end of the flange inclined surface 12 when the weir section 30 elastically deforms to tilt axially outward due to vibrations from the engine, when getting in and out of the vehicle, or vibrations due to the shift in 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, preferably 0.6 mm to 0.8 mm. In this example, the thickness of the canopy lip 31 is smaller than that of the conventional canopy lip 111 (see Figure 6), making it more flexible and prone to elastic deformation.

[0074] In the structure of this example, on the axial inner surface of the rotating flange 10, there is a sharp corner, or ridge 33, at the connection point between the flange inclined surface portion 12 and the inner inclined surface portion 13, that is, at the radially inner edge portion P2 of the flange inclined surface portion 12. Therefore, at the upper part of the hub unit bearing 1, water Wa that falls onto the axial inner surface of the rotating flange 10 and flows downward along this axial inner surface tends 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 does not move in the circumferential direction, but forms a large mass and drips onto the sliding contact area between the tip of the contact lip 32 and the axial inner surface of the rotating flange 10.

[0075] In contrast, in this example, as described above, vibrations from the engine, during boarding and alighting, and vibrations due to the shift in the vehicle's center of gravity after stopping can cause the canopy lip 31, together with the weir portion 30, to reciprocate elastically, tilting axially, as shown by the dashed line in Figure 3, starting from the radially inner end of the portion of the weir portion 30 located radially outward from the outward flange portion 27. Furthermore, in this example, the gap between the edge portion P1 and the edge portion P2 is narrowed to a level that allows the edge portion P1 to lightly contact the radially inner end of the flange inclined surface portion 12 when such elastic deformation occurs. Therefore, in this example, when the above-mentioned elastic deformation occurs, the axially outer edge portion P1 of the inner circumferential surface of the canopy lip 31 can intermittently contact the water Wa accumulated at the radially inner end of the flange inclined surface portion 12. This allows the water Wa to move circumferentially, preventing it from forming large clumps. As a result, it is possible to suppress the dripping of large clumps of water Wa onto the sliding contact area between the tip of the contact lip 32 and the axial inner surface of the rotating flange 10.

[0076] In this example, the relative positions of the edges P1 and P2 are regulated so that, throughout the entire range in which the weir section 30 and the canopy lip 31 can elastically reciprocate and tilt in the axial direction as shown by the dashed line in Figure 3, the axially outer edge P1 of the inner circumferential surface of the canopy lip 31 is located axially outward (to the left in Figure 3) than the radially inner edge P2 of the flange inclined surface section 12. In other words, in this example, regardless of the occurrence of vibration, the state in which the edge P1 is always located axially outward than the edge P2 and the tip of the canopy lip 31 is radially superimposed on the edge P2 is maintained. By adopting this configuration in this example, the function of the canopy lip 31 is always performed well.

[0077] The contact lip 32 is positioned radially inward of the canopy lip 31 and extends axially outward and radially outward from the portion that axially overlaps with the outward flange portion 27 of the core metal 24. The tip of the contact lip 32 slides around the entire circumference of the inner inclined surface portion 13, which is located radially inward of the flange inclined surface portion 12 on the axial inner surface of the rotating flange 10.

[0078] The contact lip 32 falls onto the axially inner surface of the rotating flange 10 at the top of the hub unit bearing 1, and prevents water droplets flowing 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 water Wa (see Figure 3) accumulates at the radially inner end of the flange inclined surface portion 12 and drips onto the sliding contact area 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 area that tends to lift the tip of the contact lip 32. Furthermore, the sliding contact area tends to remain wet, accelerating the wear of the contact lip 32. In contrast, the structure of this example, as described above, can prevent water Wa (see Figure 3) accumulated at the radially inner end of the flange inclined surface portion 12 from accumulating as a large mass and dripping onto the sliding contact area between the tip of the contact lip 32 and the axially inner surface of the rotating flange 10, thus making it easier to ensure the sealing performance and durability of the contact lip 32. In other words, the hub unit bearing 1 of this example makes it easier to suppress deterioration of sealing performance and wear of the contact lip 32 caused by water Wa accumulating at the radially inner end of the flange inclined surface portion 12.

[0080] In the structure of this example, within a virtual plane containing the central axis of the hub 3, the axially outer edge P3 of the outer circumferential surface of the contact lip 32 is positioned radially at a location where the tangent L of the radially inner edge P2 of the flange inclined surface 12 passes, or at a radial location further inward than the tangent L. Therefore, when water Wa, which has flowed rapidly down along the flange inclined surface 12, is ejected from the radially inner edge P2 (ridge 33) of the flange inclined surface 12 in the direction of the tangent L, the ejected 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. Thus, the sealing performance and durability of the contact lip 32 can be easily ensured by this action.

[0081] In this example, the contact lip 32 extends axially and radially outward from the portion that overlaps axially with the radially outer portion of the outward flange portion 27 of the core metal 24. Therefore, it is possible to suppress elastic deformation that causes the contact lip 32 to tilt due to vibrations from the engine, when getting in and out of the vehicle, and vibrations caused by the shift in the center of gravity of the vehicle body after it has stopped. Consequently, the interference fit of the sliding contact portion of the tip of the contact lip 32 with the axially inner surface of the rotating flange 10 can be stabilized, that is, the sealing performance of the contact lip 32 can be stabilized.

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

[0083] [Example 2] A second example of a hub unit bearing according to the embodiments of this disclosure will be described with reference to Figure 4.

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

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

[0086] In this example, a constricted portion 35 is provided at the radially inward end of the portion of the weir 30a located radially outward from the outward flange portion 27, thereby reducing the rigidity of the end. This makes it easier for the weir 30 and the canopy lip 31 to elastically reciprocate and oscillate axially, starting from the constricted portion 35, due to vibrations from the engine, when getting in and out of the vehicle, and vibrations due to the shift in the center of gravity of the vehicle body after stopping. This makes it easier for the axially outward edge P1 of the inner circumferential surface of the canopy lip 31 to intermittently contact the water Wa accumulated at the radially inward end of the flange inclined surface portion 12. The other configurations and effects of the second example are the same as those of the first example.

[0087] [Example 3] A third example of a hub unit bearing according to the embodiments of this disclosure will be described with reference to Figure 5.

[0088] In the seal ring 5b constituting the hub unit bearing of this example, the weir portion 30b extends axially inward from a portion located radially inward of the constricted portion 35 and further comprises a cylindrical portion 37 fitted onto the outer circumferential surface of the axially outer end of the outer ring 2. That is, the weir portion 30b of this example has an L-shaped cross-section. The cylindrical portion 37 can be fitted onto the outer circumferential surface of the axially outer end of the outer ring 2 with an overlap.

[0089] In this example, since the weir portion 30b includes a cylindrical portion 37 fitted onto the outer circumferential surface of the axially outer end of the outer ring 2, it is possible to more effectively prevent water droplets that have flowed axially outward along the outer circumferential surface of the outer ring 2 from entering the space between the axially outer end 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 the same as those of the second example. [Explanation of Symbols]

[0090] 1 Hub unit bearing 2 Outer ring 3 Hubs 4a, 4b Rolling elements 5, 5a, 5b sealing rings 6a, 6b Outer ring track 7. Stationary flange 8 Support hole 9a, 9b Inner ring track 10 Rotating flanges 11. Pilot Section 12 Flange inclined surface 13 Inner slope section 14 Plane part 15 Curved section 16 Cylindrical surface part 17 Recess 18 mounting holes 19 Hub Wheel 20 Inner circle 21 Spline holes 22a, 22b retainer 23 Rolling element installation space 24 Mandrel 25 sealant 26 Fitting cylinder 27 Outward-facing flange 28 Support plate part 29a, 29b, 29c Seal Lip 30, 30a, 30b Weir 31. Canopy Lip 32 Contact Lip 33 Ridge 34 Combination sealing rings 35. Constricted area 36 Circumferential groove 37 Cylindrical section 100 Hub Unit Bearings 101 Outer ring 102 Hub 103 Rolling element installation space 104 Seal ring 105 Mandrel 106 Sealant 107 Seal Lip 108 Seal Lip 109 Seal Lip 110 Weir 111 Visor Lip 112 Contact Lip 113 Sliding ring 114 Disc section 115 Cylindrical section 116 Rotating flange 117 Flange inclined surface 118 Ridge

Claims

1. An outer ring having a double row of outer ring raceways on its inner circumference, A hub having double rows of inner ring raceways on its outer circumferential surface, and a rotating flange protruding radially outward in the portion located axially outward from the outer ring, A plurality of rolling elements are arranged to roll freely between the double-row outer ring raceway and the double-row inner ring raceway, A seal ring that closes the axially outer opening of the rolling element installation space located between the inner circumferential surface of the outer ring and the outer circumferential surface of the hub, Equipped with, The rotating flange has a flange inclined surface portion in the radial middle of its axial inner surface, which is inclined in a direction toward the axial inner as it moves toward the radial inner surface. The seal ring comprises a core metal supported at the axially outer end of the outer ring, and a sealing material coupled to the core metal. The sealing material has at least one sealing lip, a weir, a canopy lip, and a contact lip. The at least one seal lip is positioned on the radially inner portion of the sealing material, The weir portion is positioned on the radially outer portion of the sealing material, extends radially outward beyond the outer circumferential surface of the axially outer end of the outer ring, and has a disc shape. The canopy lip extends axially and radially outward from a portion of the weir that is located radially outward from the core metal, and has an axially outward edge of the inner circumferential surface that is located radially outward from the radially inward edge of the flange inclined surface and is in close proximity to the edge, and is able to contact the radially inward end of the flange inclined surface when the weir is elastically deformed so as to tilt axially outward. The contact lip is positioned radially inward of the canopy lip, extends axially outward and radially outward from the portion that axially overlaps with the core metal, and has a tip that slides against a portion of the axially inward surface of the rotating flange that is located radially inward of the flange inclined surface portion. Hub unit bearing.

2. The hub unit bearing according to claim 1, wherein, in the free state of the weir and the canopy lip, the distance between the axially outer edge of the inner circumferential surface of the canopy lip and the radially inner edge of the flange inclined surface is restricted to 0.4 mm to 1.0 mm.

3. The hub unit bearing according to claim 1, wherein the base end of the canopy lip is connected to the radially intermediate portion of the weir.

4. An outer ring having a double row of outer ring raceways on its inner circumference, A hub having double rows of inner ring raceways on its outer circumferential surface, and a rotating flange protruding radially outward in the portion located axially outward from the outer ring, A plurality of rolling elements are arranged to roll freely between the double-row outer ring raceway and the double-row inner ring raceway, A seal ring that closes the axially outer opening of the rolling element installation space located between the inner circumferential surface of the outer ring and the outer circumferential surface of the hub, Equipped with, The rotating flange has a flange inclined surface portion in the radial middle of its axial inner surface, which is inclined in a direction toward the axial inner as it moves toward the radial inner surface. The seal ring comprises a core metal supported at the axially outer end of the outer ring, and a sealing material coupled to the core metal. The sealing material has at least one sealing lip, a weir, a canopy lip, and a contact lip. The at least one seal lip is positioned on the radially inner portion of the sealing material, The weir portion is positioned on the radially outer portion of the sealing material and protrudes radially outward from the outer circumferential surface of the axially outer end of the outer ring. The canopy lip extends axially and radially outward from a portion of the weir that is located radially outward from the core metal, and has an axially outward edge of the inner circumferential surface that is located radially outward from the radially inward edge of the flange inclined surface and is in close proximity to and facing the said edge. The contact lip is positioned radially inward of the canopy lip, extends axially outward and radially outward from the portion that overlaps axially with the core metal, and has a tip that slides against a portion of the axially inward surface of the rotating flange that is located radially inward of the flange inclined surface portion. Of the weir portion, the portion located radially between the core metal and the base end of the canopy lip has a constricted portion with a smaller axial thickness compared to the radially adjacent portion. Hub unit bearing.

5. The hub unit bearing according to claim 4, wherein the weir portion extends axially inward from a portion located radially inward from the constricted portion and comprises a cylindrical portion that is fitted onto the outer circumferential surface of the axially outer end of the outer ring.

6. The hub unit bearing according to any one of claims 1 to 5, wherein in a virtual plane including the central axis of the hub, the radially inner end of the flange inclined surface portion is positioned at a location that intersects with a virtual line formed by the movement trajectory of the axially outer edge of the inner circumferential surface of the canopy lip when the weir portion is elastically deformed and its extension.

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