JP2024061144A - Hub unit bearing - Google Patents

Abstract

[Problem] To provide a hub unit bearing that can reduce the thickness of a dam portion and suppress reversal of the dam portion when the seal ring is attached. [Solution] A seal ring (5) that closes an axially outer opening of a rolling element installation space (20) is composed of a core metal (25) and a seal material (26). The seal material (26) has a dam portion (35) that protrudes radially outward beyond the axially outer end of an outer ring (2) and has at least a part of its inner circumferential surface in contact with the axially outer end outer circumferential surface of the outer ring (2). The core metal (25) is composed of an inner diameter side core metal (27) that is fitted and fixed to the axially outer end of the outer ring (2), and an outer diameter side core metal (28) that is separate from the inner diameter side core metal (27) and that reinforces the dam portion (35), with at least a part of it positioned radially outward beyond the axially outer end outer circumferential surface of the outer ring (2). [Selected Figure] Figure 2

Description

The present invention relates to a hub unit bearing.

The wheels of an automobile are supported rotatably relative to the suspension by a hub unit bearing. 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 from a portion located axially outward from the outer ring, and a number 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. The wheels of the wheels and the braking rotors are connected and fixed to the rotating flange of the hub.

Note that with regard to hub unit bearings, the axially outer side refers to the outer side in the width direction of the vehicle when it is installed on the vehicle, and the axially inner side refers to the center side in the width direction of the vehicle when it is installed on the vehicle.

The hub unit bearing further includes a seal device that closes the 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 to prevent the intrusion of muddy water and the like from the outside. A seal ring that is supported and fixed to the axially outer end of the outer ring and has multiple seal lips whose tips are in sliding contact with the axially middle outer peripheral surface of the hub or the axially inner surface of the rotating flange over the entire circumference has been widely known as such a seal device.

In addition, to prevent muddy water and other moisture adhering to the outer peripheral surface of the outer ring from entering the rolling element installation space along the outer peripheral surface of the outer ring, a dam portion that protrudes radially outward beyond the axially outer end of the outer ring is provided on the seal ring that closes the axially outer opening of the rolling element installation space. To increase the effectiveness of the dam portion in preventing the intrusion of foreign matter, it is preferable to have the inner peripheral surface of the dam portion contact the entire outer peripheral surface of the axially outer end of the outer ring.

JP 2017-48809 A (Patent Document 1) discloses a structure in which a part of the inner peripheral surface of the dam portion (annular convex portion) is in contact with the outer peripheral surface of the axially outer end of the outer ring over the entire circumference.

Figure 10 shows the conventional structure described in JP 2017-48809 A. In the illustrated example, the dam portion 100 is reinforced by placing a part of the core metal 102 inside the dam portion 100 to increase the rigidity of the dam portion 100 and prevent the dam portion 100 from inverting when the seal ring 101 is attached to the outer ring 103.

Specifically, the radially outer end of the outward flange 105, which extends radially outward from the axially outer end of the seal fitting tubular portion 104, which is fixed to the outer ring 103, of the core metal 102 constituting the seal ring 101, the substantially cylindrical tubular portion 106, and the bent connection portion 107, which has an arc-shaped cross section and connects the outward flange 105 and the tubular portion 106, are arranged inside the dam portion 100. With this configuration, the rigidity of the dam portion 100 is increased, and when the seal ring 101 is attached to the outer ring 103, the dam portion 100 is prevented from floating outward in the radial direction, and the dam portion 100 is prevented from being inverted. If the seal ring 101 is attached to the outer ring 103 with the dam portion 100 in an inverted state, the sealing effect of the dam portion 100 may be insufficient in some cases, which may lead to the intrusion of muddy water, etc.

JP 2017-48809 A JP 2022-48883 A

The dam portion provided on the seal ring protrudes radially outward beyond the axially outer end of the outer ring, so the dam portion or a portion of the core metal reinforcing the dam portion is disposed close to a connecting member such as a stud or hub bolt for connecting and fixing the wheel and the braking rotor to the rotating flange. For this reason, in a hub unit bearing in which the difference between the outside diameter of the axially outer end of the outer ring and the pitch circle diameter of the connecting member is small, it is necessary to reduce the radial thickness of the dam portion and make the dam portion thinner in order to prevent interference between the dam portion or the portion of the core metal reinforcing the dam portion and the connecting member.

However, as in the conventional structure described in JP 2017-48809 A, when the core bar 102 includes not only the tubular portion 106, which is effective in preventing the dam portion 100 from floating up, but also the bent connection portion 107 that connects the tubular portion 106 and the outward flange portion 105, and is disposed inside the dam portion 100, it is difficult to reduce the thickness of the dam portion 100.

That is, the core bar 102, which is made by bending a metal plate, needs to have a radius of curvature of the corner R of the bent connection part 107 at least larger than the plate thickness of the core bar 102 due to the constraints of press processing. Therefore, when the bent connection part 107 connecting the tube part 106 and the outward flange part 105 is arranged inside the dam part 100, the radial dimension from the outer peripheral surface of the axially outer end part of the outer ring 103 to the inner peripheral surface of the tube part 106 becomes large, making it difficult to thin the dam part 100. In addition, in order to press the tube part 106, it is necessary to form a flange part bent radially outward from the axially inner end part of the tube part 106, and after forming the tube part 106 while holding down the flange part, to remove the flange part by trimming. Therefore, the maximum diameter part (trimming part) of the core bar 102 becomes larger than the tube part 106, and is likely to interfere with the connecting member.

In response to this, it is possible to adopt a structure in which a core bar is not placed inside the dam portion and the dam portion is not reinforced by a core bar, as in the conventional structure described in, for example, JP 2022-48883 A (Patent Document 2). However, if such a structure is adopted, it is necessary to ensure that the dam portion has a sufficient radial thickness to make it less likely to deform in order to prevent the dam portion from inverting when the seal ring is installed, making it difficult to reduce the thickness of the dam portion.

The present invention was made to solve the above problems, and aims to provide a hub unit bearing that can reduce the thickness of the dam portion and prevent the dam portion from reversing when the seal ring is installed.

A hub unit bearing according to one aspect of the present invention includes an outer ring, a hub, a plurality of rolling elements, and a seal ring.
The outer ring has a double row outer ring raceway on its inner circumferential surface.
The hub has a double row inner ring raceway on its outer circumferential surface.
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.
The seal ring has a metallic, annular core bar fixed to the axially outer end of the outer ring, and an elastic sealing material bonded and fixed to the core bar, and closes the axially outer opening of the rolling element installation space existing between the inner surface of the outer ring and the outer surface of the hub.
The sealing material has a dam portion that protrudes radially outward beyond the axially outer end of the outer ring and has at least a part of its inner circumferential surface in contact with the axially outer end outer circumferential surface of the outer ring.
The core bar consists of an inner diameter side core bar that is fitted and fixed into the axially outer end part of the outer ring, and an outer diameter side core bar that is separate from the inner diameter side core bar, at least a portion of which is positioned radially outward from the outer peripheral surface of the axially outer end part of the outer ring and reinforces the dam portion.

In a hub unit bearing according to one aspect of the present invention, the inner diameter side core bar and the outer diameter side core bar can be arranged close to each other at a distance equal to or less than the thickness of at least one of the inner diameter side core bar or the outer diameter side core bar.

In one aspect of the hub unit bearing of the present invention, the inner diameter side core metal has an outward flange portion that extends radially along the axially outer end face of the outer ring, and the outer diameter side core metal is made up of a cylindrical tube portion, a circular ring portion, and a bent portion that connects the circular ring portion and the outer diameter side core metal, and has a substantially L-shaped cross section, and the radially outer end portion of the outward flange portion and the bent portion can be arranged to overlap in the axial direction.

In one aspect of the hub unit bearing of the present invention, the inner diameter side core metal has an outward flange portion that extends radially along the axially outer end face of the outer ring, and the outer diameter side core metal is made up of a cylindrical tube portion, a circular ring portion, and a bent portion that connects the circular ring portion and the outer diameter side core metal, and has a substantially L-shaped cross section, and the radially outer end of the outward flange portion and the circular ring portion can be arranged to overlap in the axial direction.

In one aspect of the hub unit bearing of the present invention, the inner diameter side core bar and the outer diameter side core bar can be arranged in close radial proximity at a distance equal to or less than the thickness of at least one of the inner diameter side core bar or the outer diameter side core bar.

The hub unit bearing according to one aspect of the present invention allows the dam portion to be made thinner and prevents the dam portion from reversing when the seal ring is installed.

FIG. 1 is a cross-sectional view showing a hub unit bearing according to a first embodiment. FIG. 2 is an enlarged view of part A in FIG. FIG. 3 is a cross-sectional view showing an example of a manufacturing process for a seal ring to be incorporated in a hub unit bearing according to the first example of the embodiment. FIG. 4 is a diagram showing a second embodiment of the present invention, and corresponds to FIG. FIG. 5 is a diagram showing a second embodiment of the present invention, and corresponds to FIG. FIG. 6 is a diagram showing a third embodiment of the present invention, and corresponds to FIG. FIG. 7 is a diagram showing a third example of the embodiment, and corresponds to FIG. FIG. 8 is a diagram showing a fourth embodiment, which corresponds to FIG. FIG. 9 is a diagram showing a fourth embodiment, which corresponds to FIG. FIG. 10 is a cross-sectional view showing a seal ring incorporated in a hub unit bearing of a conventional structure.

[First Example of the Embodiment]
A first example of the embodiment will be described with reference to FIGS. 1 to 3. FIG.

The hub unit bearing of the present invention can be applied to hub unit bearings of various structures, but in this example, we will explain its application to a hub unit bearing for a driven wheel.

The hub unit bearing 1 in this example comprises an outer ring 2, a hub 3, a number of rolling elements 4a, 4b, and a seal ring 5.

In the following description of the hub unit bearing 1, the left side of Fig. 1 and Fig. 2, which is located on the outer side in the width direction of the vehicle when assembled to the vehicle, is referred to as the outer axial side, and the right side of Fig. 1 and Fig. 2, which is located on the center side in the width direction of the vehicle when assembled to the vehicle, is referred to as the inner axial side.

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 in the axially middle portion. The stationary flange 7 has support holes 8 that penetrate in the axial direction at multiple circumferential locations in the radially middle portion.

In this example, the support hole 8 is configured as a screw hole. The outer ring 2 is supported and fixed to the suspension by inserting a support bolt through a through hole provided in the knuckle of the suspension device and screwing it into the support hole 8 of 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.

The outer ring 2 has a cylindrical surface portion 48 on the outer peripheral surface at the axially outer end, whose outer diameter does not change along the axial direction. The outer ring 2 has an inclined surface portion 49 on the outer peripheral surface adjacent to the axially inner side of the cylindrical surface portion 48, whose outer diameter decreases toward the axially outer side.

The hub 3 has double-row inner ring raceways 9a, 9b on its outer circumferential surface. Furthermore, the hub 3 has a rotating flange 10 that protrudes radially outward at a portion located axially outward from the outer ring 2. The hub 3 also 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 with the outer ring 2.

The hub 3 in this example has a groove shoulder 21 on the outer peripheral surface located between the rotating flange 10 and the axially outer inner ring raceway 9a. The groove shoulder 21 is directly connected to the radially inner end of the axially inner surface of the rotating flange 10, and is also directly connected to the axially outer inner ring raceway 9a. The axially inner half of the groove shoulder 21 is configured as a cylindrical surface, and the axially outer half of the groove shoulder 21 is configured as a curved surface having an arc-shaped cross-sectional shape.

The rotating flange 10 has mounting holes 12 that penetrate the axial direction at multiple circumferential locations in the radially middle portion. A stud 13 for connecting and fixing a braking rotor such as a disk or drum and a wheel that constitutes a wheel to the rotating flange 10 is press-fitted into each mounting hole 12 with a serration. That is, in this example, the mounting hole 12 is configured as a cylindrical hole.

The axially inner surface of the rotating flange 10 has an inner flat surface 22 adjacent to the radially outer side of the groove shoulder 21, and an outer flat surface 23 located axially outward from the inner flat surface 22 in a portion located radially outward from the inner flat surface 22. Furthermore, the axially inner surface of the rotating flange 10 has a step 24 that is approximately a conical cylindrical surface facing radially outward at the connection between the inner flat surface 22 and the outer flat surface 23. In the illustrated example, the outer diameter of the boundary between the inner flat surface 22 and the step 24 is approximately the same as the outer diameter of the axially outer end of the outer ring 2.

The rotating body for braking, such as a brake disc, and the wheel of a wheel are fixed to the rotating flange 10 by inserting the pilot part 11 into the central hole provided in the center of each, and inserting the studs 13 into the through holes provided at multiple points in the circumferential direction of each radial middle part, and then screwing a hub nut (not shown) onto the tip of the stud 13.

The mounting holes of the rotating flange can also be configured as threaded holes. In this case, the braking rotor and the wheel are fixed to the rotating flange by threading a hub bolt, which is inserted through a through hole in the braking rotor and a through hole in the wheel, into the mounting hole from the outside in the axial direction.

In this example, the hub 3 is made up of an inner ring 14 and a hub wheel 15.

The inner ring 14 is made of a hard metal such as bearing steel. The inner ring 14 has an inner ring raceway 9b on the axially inner side on its outer circumferential surface.

The hub ring 15 is made of a hard metal such as medium carbon steel. The hub ring 15 has an inner ring raceway 9a on the axially outer side, a rotating flange 10, and a pilot portion 11.

The hub ring 15 has a small diameter step 16, located axially inward of the axially outer inner ring raceway 9a, which has a smaller outer diameter than the adjacent axially outer portion and onto which the inner ring 14 is fitted. Furthermore, the hub ring 15 has a step surface 17 facing axially inward at the axially outer end of the small diameter step 16, and a crimped portion 18 bent radially outward from the axially inner end of the small diameter step 16.

The hub 3 is constructed by fitting the inner ring 14 onto the small diameter step 16 of the hub wheel 15, and clamping the inner ring 14 between the step surface 17 and the crimped portion 18 of the hub wheel 15 from both axial sides, thereby connecting and fixing the inner ring 14 to the hub wheel 15. The hub wheel and the inner ring can also be connected by screwing a nut onto the axially inner end of the hub wheel that protrudes from the axially inner end of the inner ring.

The hub unit bearing 1 in this example is a hub unit bearing for a driven wheel, so the hub 3 is solid. However, one aspect of the hub unit bearing of the present invention can also be used as a hub unit bearing for a driving wheel. In this case, the hub has a spline hole that penetrates in the axial direction at the center. The tip of the drive shaft, which is rotated and driven by an engine or electric motor as a drive source, is spline-engaged with the spline hole. When the vehicle is traveling, the hub is rotated by the drive shaft, which rotates and drives the wheel and braking rotor that are connected and fixed to the rotating flange of the hub.

The rolling elements 4a, 4b are made of iron alloys such as bearing steel or ceramics, and are arranged between the double row outer ring raceways 6a, 6b and the double row inner ring raceways 9a, 9b, with multiple rolling elements held by retainers 19a, 19b. As a result, the hub 3 is supported rotatably on the radial inside of the outer ring 2.

The hub unit bearing 1 of this example has an equal diameter PCD type structure in which the pitch circle diameter of the rolling elements 4a in the axially outer row is equal to the pitch circle diameter of the rolling elements 4b in the axially inner row. However, the hub unit bearing of one aspect of the present invention can also be applied to a unequal diameter PCD type hub unit bearing in which the pitch circle diameter of the rolling elements in the axially outer row is larger or smaller than the pitch circle diameter of the rolling elements in the axially inner row. Also, although balls are used as the rolling elements 4a and 4b in the hub unit bearing 1 of this example, tapered rollers can be used instead of balls.

The seal ring 5 closes the axially outer opening of the rolling element installation space 20 that exists between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3.

The seal ring 5 has a metal, annular core 25 fixed to the axially outer end of the outer ring 2, and an elastic seal member 26 bonded and fixed to the core 25.

The core bar 25 has a two-piece structure consisting of an inner core bar 27 and an outer core bar 28.

The inner diameter side core metal 27 and the outer diameter side core metal 28 are constructed separately from each other. However, the inner diameter side core metal 27 and the outer diameter side core metal 28 are joined by the sealing material 26 and constitute one seal ring 5.

The inner diameter core metal 27 is formed into an annular shape by pressing a metal plate such as a mild steel plate into a bent shape.

The inner diameter side core metal 27 is provided with a seal fitting tubular portion 29 that is tightly fitted into the axially outer end of the outer ring 2, an outward flange portion 30 that bends radially outward from the axially outer end of the seal fitting tubular portion 29 and extends radially outward along the axially outer end face of the outer ring 2, and a support plate portion 31 that is folded back radially inward in a U-shape from the axially inner end of the seal fitting tubular portion 29 and whose axially outer end extends radially inward.

In this example, the radially outer end of the outward flange portion 30 is a free end that protrudes slightly radially outward from the axially outer end of the outer ring 2. In the illustrated example, the radially outer end of the outward flange portion 30 protrudes radially outward from the axially outer end of the outer ring 2 by an amount approximately equal to the plate thickness _t27 of the inner diameter side core metal 27.

The outer diameter side core bar 28, like the inner diameter side core bar 27, is formed into an annular shape by pressing and bending a rust-resistant metal plate, such as a rust-resistant mild steel plate or stainless steel plate.

In this example, the thickness _t28 of the outer diameter side core metal 28 is the same as the thickness _t27 of the inner diameter side core metal 27 ( _t28 = _t27 ). However, the thickness _t28 of the outer diameter side core metal 28 may be thicker or thinner than the thickness _t27 of the inner diameter side core metal 27.

The outer diameter side core metal 28 is disposed at the radially outer end of the seal ring 5, and reinforces the dam portion 35 (described below) that constitutes the seal material 26. The outer diameter side core metal 28 is disposed radially outward of the inner diameter side core metal 27. The outer diameter side core metal 28 and the inner diameter side core metal 27 are disposed overlapping each other in the radial direction.

In this example, the outer diameter side core bar 28 has an inner diameter larger than the outer diameter of the inner diameter side core bar 27.

The outer core metal 28 has a substantially L-shaped cross section to increase rigidity. The outer core metal 28 is made up of a cylindrical tube portion 32, a ring portion 33, and a bent portion 34 with a substantially arc-shaped cross section that connects the ring portion 33 and the tube portion 32.

In this example, the ring portion 33 is configured as an outward flange extending radially outward. The radial dimension of the ring portion 33 is sufficiently shorter than the axial dimension of the tubular portion 32. The ring portion 33 extends in a direction perpendicular to the central axis of the tubular portion 32.

In this example, the bent portion 34 connects the axially outer end of the tubular portion 32 and the radially inner end of the annular portion 33, and is curved in a radially outward direction as it moves axially outward.

At least a portion of the outer diameter side core metal 28 is positioned radially outward from the cylindrical surface portion 48, which is the outer peripheral surface of the axially outer end portion of the outer ring 2. In this example, the entire outer diameter side core metal 28 is positioned radially outward from the cylindrical surface portion 48.

The tube portion 32 of the outer diameter side core metal 28 is arranged approximately parallel to the cylindrical surface portion 48 of the outer ring 2 and overlaps radially with the axially outer end portion of the outer ring 2. In contrast, the circular ring portion 33 and the bent portion 34 of the outer diameter side core metal 28 are arranged axially outward from the axially outer end face of the outer ring 2.

The tube portion 32 has a cylindrical inner peripheral surface and a cylindrical outer peripheral surface. The outer peripheral surface and the axially inner end face of the tube portion 32 are exposed to the outside without being covered by the sealing material 26. The tube portion 32 reinforces the dam portion 35 (dam portion protrusion 37) described below that constitutes the sealing material 26 from the radial outside, and prevents the dam portion 35 from floating up radially outward.

The outer peripheral surface, axial inner surface, and radial outer portion of the axial outer surface of the ring portion 33 are exposed to the outside without being covered by the seal material 26. In addition, of the bent portion 34, the corner R portion 50 connecting the outer peripheral surface of the tube portion 32 and the axial inner surface of the ring portion 33 is exposed to the outside without being covered by the seal material 26. The ring portion 33 and the bent portion 34 are positioned so as to radially overlap the outward flange portion 30 of the inner diameter side core metal 27.

The inner diameter side core metal 27 and the outer diameter side core metal 28 are arranged close to each other while being spaced apart from each other. In this example, the inner diameter side core metal 27 and the outer diameter side core metal 28 are arranged close to each other at a distance equal to or less than the plate thicknesses _t27 , t28 of the inner diameter side core metal ₂₇ and the outer diameter side core metal ₂₈ , respectively. Specifically, the inner diameter side core metal 27 and the outer diameter side core metal 28 are arranged close to each other in the radial direction at a distance equal to or less than the plate thicknesses t27, _t28 of the inner diameter side core metal 27 and the outer diameter side core metal 28, respectively. In other words, the inner diameter side core metal 27 and the outer diameter side core metal 28 are separated from each other via a gap (radial gap) G equal to or less than the plate thicknesses _t27, t28 of the inner diameter side core metal 27 and the outer diameter side core metal ₂₈ , respectively (0<G≦ _t27 = _t28 ).

The size of the gap G between the inner diameter side core metal 27 and the outer diameter side core metal 28 can be determined as appropriate, but is preferably set in the range of 0.2 to 0.8 times, and more preferably 0.4 to 0.6 times, the plate thicknesses t ₂₇ and t _28. If the size of the gap G is made smaller than 0.2 times the plate thicknesses t ₂₇ and t ₂₈ , the molten rubber may not flow well around the dam portion projection 37, resulting in underfill. In contrast, if the size of the gap G is made larger than 0.8 times the plate thicknesses t ₂₇ and t ₂₈ , the effect of reducing the diameter of the annular portion 33 is likely to be lost.

In addition, when the plate thickness _t27 of the inner diameter side core bar 27 and the plate thickness _t28 of the outer diameter side core bar 28 are made different, the inner diameter side core bar 27 and the outer diameter side core bar 28 are made closer to each other than the plate thickness of the core bar having the larger plate thickness between the inner diameter side core bar 27 and the outer diameter side core bar 28.

In this example, the inner diameter side core bar 27 and the outer diameter side core bar 28 are closest to each other in the portion between the outer peripheral surface of the outward flange portion 30 of the inner diameter side core bar 27 and the inner peripheral surfaces of the tubular portion 32 and the bent portion 34 of the outer diameter side core bar 28, and a gap G in this portion is equal to or smaller than the plate thicknesses t ₂₇ , t ₂₈ of the inner diameter side core bar 27 and the outer diameter side core bar 28, respectively. In this example, assuming that the outward flange portion 30 of the inner diameter side core bar 27 and the tubular portion 32 of the outer diameter side core bar 28 are connected by a bent connection portion having an arc-shaped cross section, the gap G between the inner diameter side core bar 27 and the outer diameter side core bar 28 is restricted to equal to or smaller than the plate thicknesses t ₂₇ , t ₂₈ that are smaller than the radius of curvature of the corner R portion of the bent connection portion. This allows the tubular portion 32 of the outer diameter side core bar 28 to be brought closer to the cylindrical surface portion 48 of the outer ring 2.

The sealing material 26 is made of an elastic material containing an elastomer such as rubber, and is bonded and fixed to the surfaces of the inner diameter side core metal 27 and the outer diameter side core metal 28 that constitute the core metal 25 by vulcanization adhesion. The sealing material 26 joins the inner diameter side core metal 27 and the outer diameter side core metal 28. Note that Figure 2 shows the shape of each part of the sealing material 26 in a free state.

The seal material 26 has a dam portion 35 that protrudes radially outward beyond the axially outer end of the outer ring 2 and has at least a portion of its inner peripheral surface in contact with the axially outer end outer peripheral surface of the outer ring 2. The dam portion 35 blocks muddy water that has flowed along the inclined surface portion 49 of the outer ring 2 to the cylindrical surface portion 48, thereby preventing the muddy water from entering between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 10.

The dam portion 35 is provided at the radially outer end of the seal ring 5. The dam portion 35 has an annular dam portion main body 36 that is located axially outward of the axially outer end face of the outer ring 2, and a substantially cylindrical dam portion protrusion 37 that is located radially outward of the axially outer end of the outer ring 2.

The dam body 36 is fixedly connected to the radially outer end of the outward flange 30 of the inner core 27, and to the annular portion 33 and bent portion 34 of the outer core 28. As a result, the dam body 36 covers the radially outer end and outer peripheral surface of both axial sides of the outward flange 30 of the inner core 27, the axially outer side surface of the annular portion 33 of the outer core 28, and the inner peripheral surface (corner R portion 51) of the bent portion 34 of the outer core 28. In other words, the dam body 36 is reinforced by the radially outer end of the outward flange 30 of the inner core 27, and the annular portion 33 and bent portion 34 of the outer core 28.

The dam portion projection 37 is fixedly connected to the tubular portion 32 of the outer diameter side core metal 28. As a result, the dam portion projection 37 covers the inner peripheral surface of the tubular portion 32 of the outer diameter side core metal 28. In other words, the dam portion projection 37 is reinforced by the tubular portion 32 of the outer diameter side core metal 28.

The dam section projection 37 has a lip section 38 on the axially inner side. The tip of the lip section 38 is in contact with the cylindrical surface section 48 of the outer ring 2 with a tightening margin. The tip of the lip section 38 has an arc-shaped cross-sectional shape in the free state.

The dam portion 35 is provided at the radially outer end of the seal base 39 that constitutes the seal material 26.

The seal base 39 covers the radially outer portion of the axially outer side, outer surface, and axially inner side of the inner core metal 27, the inner surface of the seal fitting tube 29, the outer surface of the radially outer part of the support plate 31, and the axially outer side, inner surface, and radially inner part of the axially inner side of the support plate 31. The seal base 39 also covers the inner surface of the tube 32, the axially outer side of the ring 33, and the inner surface of the bent portion 34 of the outer core metal 28. In short, the dam portion 32 is composed of the seal base 39, which covers the radially outer end and outer surface of both axial sides of the outward flange 30, the inner surface of the tube 32, the axially outer surface of the ring 33, and the inner surface of the bent portion 34.

A concave knurled portion 42 is provided in the radial middle of the portion of the seal base 39 that covers the axially outer surface of the outward flange 30. The knurled portions 42 are provided intermittently in the circumferential direction in the portion of the seal base 39 that covers the axially outer surface of the outward flange 30. The knurled portions 42 are formed when the seal ring 5 is manufactured by pressing the axially outer surface of the outward flange 30 of the inner diameter core metal 27 with a part of the molding die 43 (upper die 45) described later.

The seal material 26 includes a seal base 39 including a dam portion 35, at least one seal lip 40a, 40b, 40c, the tip of which is in sliding contact with the axial inner surface of the rotating flange 10 or the axial middle outer peripheral surface of the hub 3, and an auxiliary lip 41. In this example, the seal material 26 has three seal lips 40a, 40b, 40c. However, when implementing a hub unit bearing according to one aspect of the present invention, the number of seal lips can be less than or more than three.

Of the three seal lips 40a, 40b, and 40c, the seal lip 40a on the outermost radial side extends from the portion of the seal base 39 that covers the axially outer side surface of the radially inner portion of the support plate portion 31 toward the axially outer side and has its tip in sliding contact with the inner flat surface portion 22 of the rotating flange 10. The seal lip 40b second from the radially outer side extends from the portion of the seal base 39 that covers the axially outer side surface of the radially inner portion of the support plate portion 31 toward the axially outer side and has its tip in sliding contact with the axially outer portion of the outer peripheral surface of the groove shoulder portion 21. The seal lip 40c on the innermost radial side extends from the portion of the seal base 39 that covers the inner peripheral surface of the support plate portion 31 toward the axially inner side and has its tip in sliding contact with the axially inner portion of the outer peripheral surface of the groove shoulder portion 21.

The auxiliary lip 41 extends from the axially outer surface of the dam body 36 of the dam 35 in a direction toward the axially and radially outward, and its tip is closely opposed to the step 24 provided on the axially inner surface of the rotating flange 10. The axially outer half of the auxiliary lip 41 overlaps the step 24 in the radial direction. A labyrinth seal is formed between the inner peripheral surface of the axially outer half of the auxiliary lip 41 and the step 24.

In this example, by installing the seal ring 5 as described above, it is possible to prevent foreign matter such as muddy water from entering the rolling element installation space 20 from the external space through the gap between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 10, and to prevent the grease sealed in the rolling element installation space 20 from leaking into the external space.

The seal ring 5 of this embodiment can be manufactured by the following manufacturing method.
That is, in this example, as shown in Figure 3, an inner diameter side core bar 27 and an outer diameter side core bar 28 are placed in a cavity 44 of a metal molding die 43, and the product can be manufactured by vulcanizing and molding an elastic material containing an elastomer such as rubber.

Specifically, the molding die 43 is composed of an upper die 45 and a lower die 46 that can move toward and away from each other. A cavity 44 is formed between the machined surface (lower surface) of the upper die 45 and the machined surface (upper surface) of the lower die 46. The machined surface of the upper die 45 has a shape that matches the contour shape of the axial outer surface of the seal ring 5. The machined surface of the lower die 46 has a shape that matches the contour shape of the axial inner surface of the seal ring 5.

In this example, in order to position the inner diameter side core bar 27 relative to the molding die 43, the inner diameter side core bar 27 is placed on the machined surface of the lower die 46, and a part of the upper die 45 presses downward at multiple circumferential points (parts where the knurled portion 42 is formed) on the axially outer side surface (upper side surface in FIG. 3) of the outward flange portion 30 of the inner diameter side core bar 27. Also, in order to position the outer diameter side core bar 28 relative to the molding die 43, the outer peripheral surface of the tube portion 32 is restrained by the inner peripheral side surface (surface facing radially inward) of the machined surface of the lower die 46, and the annular portion 33 is sandwiched from both sides between the upper die 45 and the lower die 46. At this time, the axially inner end surface (lower end surface in FIG. 3) of the tube portion 32 abuts against the machined surface of the lower die 46.

In this example, after the inner diameter side core metal 27 and the outer diameter side core metal 28 are positioned, an elastic material containing an elastomer such as rubber is vulcanized and molded in the cavity 44. This produces the seal ring 5. Note that the preformed material such as rubber (unvulcanized rubber) is placed on the upper mold 45 side, and a part of it moves through the gap G between the inner diameter side core metal 27 and the outer diameter side core metal 28 to the part of the cavity 44 that is located radially inside the outer diameter side core metal 28.

The hub unit bearing 1 of this example further includes a cylindrical bearing cap 47 (see FIG. 1) with a bottom that closes the axially inner opening of the rolling element installation space 20. This prevents foreign matter from the external space from entering the rolling element installation space 20 through the opening, and prevents grease sealed in the rolling element installation space 20 from leaking into the external space. Note that instead of the bearing cap 47, the axially inner opening of the rolling element installation space 20 can also be closed with a combination seal ring.

According to the hub unit bearing 1 of this embodiment, the dam portion 35 can be made thinner, and reversal of the dam portion 35 when the seal ring 5 is attached can be suppressed.
That is, in this example, the core bar 25 constituting the seal ring 5 is composed of an inner diameter side core bar 27 and an outer diameter side core bar 28 which are constructed separately from each other, and the outer diameter side core bar 28 which can suppress the lifting of the dam portion 35 is not connected to the inner diameter side core bar 27 via a bent connection portion, so that it is not necessary to arrange the bent connection portion inside the dam portion 35. Therefore, in this example, the tubular portion 32 of the outer diameter side core bar 28 can be arranged closer to the cylindrical surface portion 48 of the outer ring 2 than in the case where the radially outer end of the outward flange portion 30 of the inner diameter side core bar 27 and the outer diameter side core bar 28 are connected by a bent connection portion.

Furthermore, in this example, the inner diameter side core bar 27 and the outer diameter side core bar 28 are disposed close to each other at a distance equal to or less than the plate thicknesses _t27 , _t28 of the inner diameter side core bar 27 and the outer diameter side core bar 28, respectively. Specifically, a gap (radial gap) G between the outer peripheral surface of the outward flange portion 30 of the inner diameter side core bar 27 and the inner peripheral surfaces of the tubular portion 32 and the bent portion 34 of the outer diameter side core bar 28 is set to be equal to or less than the plate thicknesses _t27 , _t28 . Therefore, the tubular portion 32 of the outer diameter side core bar 28 can be disposed effectively close to the cylindrical surface portion 48 of the outer ring 2.

As a result, it is possible to reduce the radial thickness (cross-sectional height) of the dam portion 35, and the dam portion 35 can be made thinner. In particular, in this example, the radial thickness of the dam portion projection 37 can be effectively reduced. Therefore, according to the hub unit bearing 1 of this example, even when a configuration is adopted in which the difference between the outer diameter of the axially outer end of the outer ring 2 and the pitch circle diameter of the stud 13 is small, interference between the stud 13 and the dam portion 35 (dam portion main body 36), or the tube portion 32 and ring portion 33 of the outer diameter side core metal 28, can be prevented.

In addition, since the dam portion 35 is reinforced by the outer diameter side core metal 28, the inner peripheral surface of the dam portion 35 can be prevented from inverting when the seal ring 5 is attached (pressed in). Specifically, since the dam portion projection 37 is reinforced by the cylindrical portion 32 of the outer diameter side core metal 28, the dam portion projection 37 can be prevented from floating up radially outward when the seal ring 5 is attached. Therefore, the lip portion 38 constituting the inner peripheral surface of the dam portion projection 37 can be prevented from inverting due to contact with the cylindrical surface portion 48 of the outer ring 2.

In addition, in this example, since the outer diameter side core metal 28 has a substantially L-shaped cross section, it is possible to sufficiently ensure the rigidity of the outer diameter side core metal 28. Therefore, even if the outer diameter side core metal 28 is formed separately from the inner diameter side core metal 27, it is possible to sufficiently ensure the reinforcing effect of the outer diameter side core metal 28 and to sufficiently reduce the plate thickness _t28 .

[Second Example of the Embodiment]
A second embodiment will be described with reference to FIGS.

This example is a modified version of the first embodiment, and only the structure of the seal ring 5a has been changed from the structure of the first embodiment.

In the seal ring 5a of this example, the bent portion 34 of the outer core metal 28a and the radially outer end of the outward flange portion 30 of the inner core metal 27 are overlapped in the axial direction. Specifically, within the bent portion 34, the corner R portion 51 that connects the inner peripheral surface of the tube portion 32a and the axially outer surface of the ring portion 33 and the radially outer end of the outward flange portion 30 are overlapped in the axial direction. In addition, the axially outer surface of the ring portion 33 of the outer core metal 28a is positioned axially inward of the axially outer surface of the outward flange portion 30 of the inner core metal 27.

In addition, in this example, the axial dimension of the tubular portion 32a of the outer diameter side core metal 28a is shorter than the axial dimension of the tubular portion 32 of the seal ring 5 in the first example of the embodiment. The dam portion protrusion 37a of the dam portion 35a covers not only the inner peripheral surface of the tubular portion 32a, but also the axially inner end face of the tubular portion 32a and the axially inner end of the outer peripheral surface.

The inner diameter side core bar 27 and the outer diameter side core bar 28a are disposed close to each other at a distance equal to or less than the plate thicknesses _t27 , _t28 (see FIG. 2) of the inner diameter side core bar 27 and the outer diameter side core bar 28a, respectively. In this example, the inner diameter side core bar 27 and the outer diameter side core bar 28a are closest to each other at a portion between a corner connecting the outer peripheral surface and the axially inner surface of the outward flange portion 30 of the inner diameter side core bar 27 and the inner peripheral surface (corner R portion 51) of the bent portion 34 of the outer diameter side core bar 28b, and a gap G in this portion is equal to or less than the plate thicknesses _t27 , _t28 .

The seal ring 5a of this example can also be manufactured using a molding die 43 consisting of an upper die 45 and a lower die 46, as shown in Figure 5. In this example, with the inner diameter side core bar 27 and the outer diameter side core bar 28a positioned relative to the molding die 43, the axially inner end face of the tubular portion 32a (the lower end face in Figure 5) is separated from the machining surface of the lower die 46.

In the present example as described above, the outer diameter side core bar 28a is positioned so that the rounded corner portion 51 of the bent portion 34 and the radially outer end portion of the outward flange portion 30 of the inner diameter side core bar 27 overlap in the axial direction, thereby shifting the position of the outer diameter side core bar 28a, i.e., its relative position with respect to the inner diameter side core bar 27, radially inward compared to the seal ring 5 of the first example of the embodiment. Furthermore, the inner diameter of the outer diameter side core bar 28a is made smaller than the outer diameter of the inner diameter side core bar 27. For this reason, the tubular portion 32a of the outer diameter side core bar 28a can be positioned closer to the cylindrical surface portion 48 of the outer ring 2.
The other configurations and effects are the same as those of the first embodiment.

[Third Example of the Embodiment]
A third embodiment will be described with reference to FIGS. 6 and 7. FIG.

This example is a modified version of the first embodiment, and only the structure of the seal ring 5b has been changed from the structure of the first embodiment.

In this example, the outer diameter side core metal 28b that reinforces the dam portion 35 has a substantially L-shaped cross section and is composed of a cylindrical tube portion 32b, a ring portion 33a, and a bent portion 34a that connects the ring portion 33a and the tube portion 32b.

However, in this example, the ring portion 33a is configured as an inward flange extending radially inward. The bent portion 34a connects the axially outer end of the tube portion 32b and the radially outer end of the ring portion 33a, and is curved radially inward as it moves axially outward.

In addition, in this example, the axial dimension of the cylindrical portion 32b is longer than the axial dimension of the cylindrical portion 32 of the seal ring 5 in the first example of the embodiment. Specifically, the entire length of the cylindrical portion 32b is extended axially outward, and the cylindrical portion 32b and the outward flange portion 30 of the inner diameter side core metal 27 are overlapped in the radial direction.

As a result, the bent portion 34a of the outer diameter side core bar 28b and the radially outer end of the outward flange portion 30 of the inner diameter side core bar 27 are overlapped in the axial direction. Specifically, within the bent portion 34a, the corner R portion 50 that connects the inner peripheral surface of the tube portion 32b and the axially inner surface of the ring portion 33a and the radially outer end of the outward flange portion 30 are overlapped in the axial direction. In this example, the ring portion 33a and the radially outer end of the outward flange portion 30 are also overlapped in the axial direction.

The inner diameter side core bar 27 and the outer diameter side core bar 28b are disposed close to each other in the radial direction at a distance equal to or less than the plate thicknesses _t27 , _t28 (see FIG. 2) of the inner diameter side core bar 27 and the outer diameter side core bar 28b, respectively. In this example, the inner diameter side core bar 27 and the outer diameter side core bar 28b are closest to each other in the portion between the outer peripheral surface of the outward flange portion 30 of the inner diameter side core bar 27 and the inner peripheral surface of the tubular portion 32b of the outer diameter side core bar 28b, and the gap (radial gap) G in this portion is equal to or less than the plate thicknesses _t27 , _t28 .

In the case of the seal ring 5b of this example, it can also be manufactured using a molding die 43 consisting of an upper die 45 and a lower die 46, as shown in Figure 7. In this example, in order to position the outer diameter side core metal 28b with respect to the molding die 43, the outer peripheral surface of the tubular portion 32b is restrained by the inner peripheral side surface of the machined surface of the lower die 46, and the radial outer portion of the axial outer side surface (upper side surface in Figure 7) of the annular portion 33a is pressed downward by the upper die 45 with the axial inner end surface (lower end surface in Figure 7) of the tubular portion 32b abutting against the machined surface of the lower die 46. The preformed material (unvulcanized rubber) is placed on the upper mold 45 side, and moves to the portion of the cavity 44 that is located radially inside the outer core bar 28b through the gap between the axially outer surface (upper surface in FIG. 7) of the outward flange portion 30 of the inner core bar 27 and the axially inner surface (lower surface in FIG. 7) of the circular ring portion 33a of the outer core bar 28b, and the gap G between the outer peripheral surface of the outward flange portion 30 of the inner core bar 27 and the inner peripheral surface of the tubular portion 32b of the outer core bar 28b.

In the present embodiment as described above, the gap G between the outer peripheral surface of the outward flange portion 30 of the inner core metal 27 and the inner peripheral surface of the tube portion 32b of the outer core metal 28b is set to be equal to or less than the plate thicknesses _t27 , _t28 , and the circular ring portion 33a of the outer core metal 28b is configured in an inward flange shape, so that not only the radial thickness of the dam portion 35b (dam portion main body 36) can be reduced, but also the outer diameter of the seal ring 5b can be effectively reduced. In addition, the radially outer end of the outward flange portion 30 of the inner core metal 27 and the circular ring portion 33a of the outer core metal 28 are arranged inside the dam portion main body 36 so as to overlap in the axial direction, so that the rigidity of the dam portion main body 36 can be improved.
The other configurations and effects are the same as those of the first embodiment.

[Fourth Example of the Embodiment]
A fourth embodiment will be described with reference to FIGS. 8 and 9. FIG.

This example is a modified version of the first embodiment, and only the structure of the seal ring 5c has been changed from the structure of the first embodiment.

In the seal ring 5c of this example, the radially inner portion of the circular ring portion 33 of the outer diameter side core metal 28c, and the corner R portion 51 of the bent portion 34 that connects the inner peripheral surface of the tube portion 32c and the axially outer surface of the circular ring portion 33 are overlapped in the axial direction with the radially outer end portion of the outward flange portion 30a of the inner diameter side core metal 27a. In addition, the axially outer surface of the circular ring portion 33 of the outer diameter side core metal 28c is positioned axially inward of the axially inner surface of the outward flange portion 30a of the inner diameter side core metal 27a.

In addition, in this example, the axial dimension of the tubular portion 32c of the outer diameter side core metal 28c is shorter than the axial dimension of the tubular portion 32 of the seal ring 5 in the first example of the embodiment.

The outer diameter of the outward flange portion 30a of the inner core metal 27a is made larger than that of the structure of the first embodiment. Specifically, in the illustrated example, the radially outer end of the outward flange portion 30a protrudes radially outward beyond the axially outer end of the outer ring 2 by more than twice the plate thickness t27 of the inner core metal ₂₇ .

The inner diameter side core bar 27a and the outer diameter side core bar 28c are disposed close to each other in the axial direction and are equal to or less than the plate thicknesses _t27 , _t28 (see FIG. 2) of the inner diameter side core bar 27a and the outer diameter side core bar 28c, respectively. In this example, the inner diameter side core bar 27a and the outer diameter side core bar 28c are closest to each other in the portion between the axially inner surface of the outward flange portion 30a of the inner diameter side core bar 27a and the axially outer surface of the circular ring portion 33 of the outer diameter side core bar 28c, and the gap (axial gap) G in this portion is equal to or less than the plate thicknesses _t27 , _t28 .

In the case of the seal ring 5c of this example, as shown in Figure 9, it can be manufactured using a molding die 43 consisting of an upper die 45 and a lower die 46. The preformed material (unvulcanized rubber) is placed on the upper die 45 side and moves to the part of the cavity 44 that is located radially inside the outer core metal 28c through the gap G between the axial inner surface (lower surface in Figure 9) of the outward flange portion 30a of the inner core metal 27a and the axial outer surface (upper surface in Figure 9) of the circular ring portion 33 of the outer core metal 28c.

In the present embodiment as described above, the outer diameter side core bar 28c is disposed so that the radially inner portion of the circular ring portion 33 and the corner R portion 51 of the bent portion 34 overlap with the radially outer end portion of the outward flange portion 30a of the inner diameter side core bar 27a in the axial direction, and the inner diameter of the outer diameter side core bar 28c is made smaller than the outer diameter of the inner diameter side core bar 27a. Therefore, the tube portion 32c of the outer diameter side core bar 28c can be disposed close to the cylindrical surface portion 48 of the outer ring 2.
The other configurations and effects are the same as those of the first embodiment.

The above describes the embodiments of the present invention, but the structures of the examples of the embodiments can be combined as appropriate as long as no contradictions arise.

The technical concept of the present invention is not limited to the structure described in the embodiment. For example, the structure and arrangement of the inner diameter side core bar and the outer diameter side core bar that make up the core bar of the seal ring can be changed as appropriate. In addition, the shape of the dam portion and the number of seal lips that make up the sealing material of the seal ring can also be changed as appropriate.

REFERENCE SIGNS LIST 1 hub unit bearing 2 outer ring 3 hub 4a, 4b rolling elements 5, 5a, 5b, 5c seal ring 6a, 6b outer ring raceway 7 stationary flange 8 support hole 9a, 9b inner ring raceway 10 rotating flange 11 pilot portion 12 mounting hole 13 stud 14 inner ring 15 hub ring 16 small diameter step portion 17 step surface 18 crimping portion 19a, 19b cage 20 rolling element installation space 21 groove shoulder portion 22 inner flat portion 23 outer flat portion 24 step portion 25 core metal 26 seal material 27, 27a inner diameter side core metal 28, 28a, 28b, 28c outer diameter side core metal 29 seal fitting cylinder portion 30, 30a outward flange portion 31 support plate portion [0033] 32, 32a, 32b Cylinder portion 33, 33a Circular ring portion 34, 34a Bent portion 35, 35a Dam portion 36 Dam portion main body 37, 37a Dam portion protrusion 38 Lip portion 39 Seal base 40a, 40b, 40c Seal lip 41 Auxiliary lip 42 Knurled portion 43 Forming die 44 Cavity 45 Upper die 46 Lower die 47 Bearing cap 48 Cylindrical surface portion 49 Inclined surface portion 50 Corner R portion 51 Corner R portion 100 Dam portion 101 Seal ring 102 Core metal 103 Outer ring 104 Seal fitting cylindrical portion 105 Outward flange portion 106 Cylinder portion 107 Bent connection portion

Claims (4)

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 its outer circumferential surface;
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 having a metal annular core fixed to an axially outer end of the outer ring and a sealing material made of an elastic material bonded and fixed to the core, the seal ring closing an axially outer opening of a rolling element installation space existing between an inner peripheral surface of the outer ring and an outer peripheral surface of the hub,
the sealing material has a dam portion that protrudes radially outward beyond an axially outer end portion of the outer ring and has at least a part of an inner circumferential surface in contact with an axially outer end outer circumferential surface of the outer ring,
the core bar comprises an inner diameter side core bar that is fitted and fixed into an axially outer end portion of the outer ring, and an outer diameter side core bar that is separate from the inner diameter side core bar and at least a portion of which is disposed radially outward from an outer peripheral surface of the axially outer end portion of the outer ring and reinforces the dam portion.
Hub unit bearing. The hub unit bearing according to claim 1, wherein the inner diameter side core bar and the outer diameter side core bar are arranged in close proximity to each other at a distance equal to or less than the thickness of at least one of the inner diameter side core bar or the outer diameter side core bar. the inner diameter side core metal has an outward flange portion extending radially along an axially outer end face of the outer ring,
the outer diameter side core metal includes a tube portion having a cylindrical shape, a ring portion having a ring shape, and a bent portion connecting the ring portion and the tube portion, and has a substantially L-shaped cross section;
The radially outer end of the outward flange portion and the bent portion are arranged to overlap in the axial direction.
2. A hub unit bearing according to claim 1. the inner diameter side core metal has an outward flange portion extending radially along an axially outer end face of the outer ring,
the outer diameter side core metal includes a tube portion having a cylindrical shape, a ring portion having a ring shape, and a bent portion connecting the ring portion and the tube portion, and has a substantially L-shaped cross section;
The radially outer end of the outward flange portion and the circular ring portion are arranged to overlap in the axial direction.
2. A hub unit bearing according to claim 1.

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