JP2024013116A - hub unit bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hub unit bearing which easily avoids a plastic deformation of a slide contact ring when installing a seal device.

SOLUTION: A seal device 5 has a slide contact ring 21, at least one support bearing 22, a first seal ring 23, and a second seal ring 24. The slide contact ring 21 is arranged around a hub 3 without contact with any of an outer ring 2, the hub 3, and rolling bodies 4a. The support bearing 22 rotatably supports the slide contact ring 21 with respect to the hub 3. The first seal ring 23 has at least one first seal lip 42a, 42b, 42c fixed to an axial outer end part of the outer ring 2 and bringing a tip part into contact with a surface of the slide contact ring 21. The second seal ring 24 has at least one second seal lip 48 fixed to the slide contact ring 21 and bringing a tip part into contact with an axial inside face of a rotary flange 10.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a hub unit bearing for rotatably supporting the wheels of an automobile relative to a suspension system.

The wheels of an automobile are rotatably supported by hub unit bearings relative to a suspension system. A hub unit bearing has an outer ring having a double-row outer ring raceway on the inner peripheral surface, a double-row inner ring raceway on the outer peripheral surface, and a portion located axially outer than the outer ring that protrudes radially outward. It includes a hub having a rotating flange, and a plurality of rolling elements rotatably disposed between a double-row outer ring raceway and a double-row inner ring raceway.

Regarding the hub unit bearing, the axially outer side is the outer side in the width direction of the vehicle when it is assembled to the vehicle, and the axially inner side is the center side in the width direction of the vehicle when it is assembled to the vehicle.

The hub unit bearing further includes a sealing device that closes an opening on the outside in the axial direction of the rolling element installation space that exists between the inner circumferential surface of the outer ring and the outer circumferential surface of the hub in order to prevent muddy water and the like from entering from the outside. .

JP-A No. 2014-240679 discloses a sliding ring formed of a metal plate in an annular shape and press-fitted onto a hub, and a plurality of seal lips whose respective tips slide into contact with the surface of the sliding ring. A hub unit bearing is described that includes a sealing device having a sealing ring fixed to an axially outer end of an outer ring.

The hub unit bearing described in Japanese Unexamined Patent Publication No. 2014-240679 has a radial groove in a portion of the outer circumferential surface of the hub adjacent to the axially inner side of the fitting cylinder provided at the radially inner end of the sliding ring. It has a convex portion that protrudes outward in the direction. Therefore, even if creep occurs at the fitting part between the hub and the sliding ring, the sliding ring will move axially inward with respect to the hub based on the engagement between the fitting cylinder part and the convex part. This can be prevented. Therefore, as the sliding ring moves axially inward with respect to the hub, the axial interference of the tip of the seal lip against the surface of the sliding ring increases, causing an inconvenience such as an increase in sealing torque. This can be prevented.

Japanese Patent Application Publication No. 2014-240679

In the conventional structure described in Japanese Unexamined Patent Publication No. 2014-240679, when assembling the sliding ring, specifically, when press-fitting the sliding ring onto the hub, the diameter of the sliding ring is expanded. , it is necessary to get over the convex part. Therefore, problems such as plastic deformation of the sliding ring may occur during the assembly work of the sliding ring.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hub unit bearing in which plastic deformation of a sliding ring can be easily avoided when a sealing device 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 device.

The outer ring has a double-row outer ring raceway on its inner peripheral surface.

The hub has a double-row inner ring raceway on its outer circumferential surface, and has a rotating flange protruding radially outward at a portion located axially outer than the outer ring.

The plurality of rolling elements are rotatably arranged between the double-row outer ring raceway and the double-row inner ring raceway.

The sealing device closes an axially outer opening of a rolling element installation space that exists between an inner circumferential surface of the outer ring and an outer circumferential surface of the hub.

The sealing device has a sliding ring, at least one support bearing, a first sealing ring, and a second sealing ring.

The sliding ring is arranged around the hub so as not to contact any of the outer ring, the hub, and the rolling elements.

The support bearing rotatably supports the sliding ring with respect to the hub. In addition, when two or more support bearings are provided, these support bearings can be arranged side by side in the axial direction.

The first seal ring is fixed to the axially outer end of the outer ring, and has at least one first seal lip whose tip is brought into contact with the surface of the sliding ring.

The second seal ring is fixed to the sliding ring and has at least one second seal lip whose tip is brought into contact with the axially inner surface of the rotating flange.

In the hub unit bearing according to one aspect of the present invention, the support bearing includes an outer support ring, an inner support ring, a support outer ring raceway provided on the inner peripheral surface of the support outer ring, and a support inner ring provided on the outer peripheral surface of the support inner ring. It has a plurality of support rolling elements arranged between the raceway and the raceway. The support outer ring is fitted inside the sliding ring, and the support inner ring is fitted outside the hub.

In the hub unit bearing according to one aspect of the present invention, the support bearing includes a support outer raceway provided on the inner peripheral surface of the sliding ring, a support inner raceway provided on the outer peripheral surface of the hub, and the support outer raceway provided on the outer peripheral surface of the hub. It has a plurality of supporting rolling elements arranged between the raceway and the supporting inner ring raceway.

In the hub unit bearing according to one aspect of the present invention, the support bearing is constituted by a sliding bearing fixed to the inner circumferential surface of the sliding ring.

According to the hub unit bearing of one aspect of the present invention, it is easy to avoid plastic deformation of the sliding ring when installing the seal device.

FIG. 1 is a sectional view of a hub unit bearing according to a first example of an embodiment of the present invention. FIG. 2 is an enlarged view of section A in FIG. FIG. 3 is a partial sectional view of a pair of support bearings constituting the sealing device for the hub unit bearing of the first example. FIG. 4 is a diagram corresponding to FIG. 2 regarding a second example of the hub unit bearing according to the embodiment of the present invention. FIG. 5 is a diagram corresponding to FIG. 2 regarding a hub unit bearing of a third example of the embodiment of the present invention. FIG. 6 is a diagram corresponding to FIG. 2 regarding a hub unit bearing according to a fourth example of the embodiment of the present invention.

[First example]
A first example of a hub unit bearing according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

Although the hub unit bearing of the present invention is applicable to hub unit bearings of various structures, in this example, a case where the present invention is applied to a hub unit bearing for a driven wheel will be described.

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

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

The outer ring 2 is made of hard metal such as medium carbon steel. The outer ring 2 has double row outer ring raceways 6a and 6b on its inner peripheral surface. Further, the outer ring 2 has a stationary flange 7 in the axially intermediate portion thereof that projects radially outward. The stationary flange 7 has support holes 8 that penetrate in the axial direction at a plurality of locations in the circumferential direction of the radially intermediate portion.

In this example, the support hole 8 is constituted by a screw hole. The outer ring 2 is supported and fixed to the suspension system by screwing support bolts inserted through holes provided in the knuckles of the suspension system into the support holes 8 of the stationary flange 7 from the inside in the axial direction, and the wheel rotates. It doesn't rotate when you do it.

The hub 3 has double-row inner raceways 9a and 9b on its outer circumferential surface, and has a rotating flange 10 projecting radially outward at a portion located axially outer than the outer ring 2. Furthermore, the hub 3 has a cylindrical pilot portion 11 at its axially outer end. The hub 3 is arranged radially inside the outer ring 2 and coaxially with the outer ring 2.

The rotating flange 10 has mounting holes 12 that penetrate in the axial direction at a plurality of locations in the circumferential direction of the radially intermediate portion. A stud 13 is press-fitted into each of the mounting holes 12 with serrations for connecting and fixing a braking rotating body such as a disk or a drum, and a wheel constituting a wheel to the rotating flange 10. That is, in this example, the attachment hole 12 is configured by a cylindrical hole.

The braking rotating body such as a brake disc and the wheel have a pilot part 11 inserted through a center hole provided at the center of each, and a pilot part 11 is provided at a plurality of locations in the circumferential direction of each radially intermediate part. The stud 13 is inserted into the through hole, and a hub nut is screwed onto the tip of the stud 13, thereby being coupled and fixed to the rotating flange 10.

Note that the mounting hole of the rotating flange can also be configured with a screw hole. In this case, a hub bolt inserted through a through hole provided in the braking rotor and a through hole provided in the wheel is screwed into the mounting hole from the outside in the axial direction. is fixed to the rotating flange.

In this example, the hub 3 is formed by combining an inner ring 14 and a hub ring 15.

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

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

The hub ring 15 has a small-diameter stepped portion 16, which has a smaller outer diameter than an adjacent portion on the axial outside, and into which the inner ring 14 is externally fitted, in a portion located axially inward of the inner ring raceway 9a on the axially outer side. . 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 radially outward from the axially inner end of the small diameter step 16. It has a caulked portion 18 bent toward.

The hub 3 is constructed by fitting the inner ring 14 onto the small-diameter stepped portion 16 of the hub ring 15 and sandwiching the inner ring 14 from both sides in the axial direction between the step surface 17 of the hub ring 15 and the caulking portion 18. 14 and a hub ring 15 are coupled and fixed.

Note that the hub ring and the inner ring can also be coupled by screwing a nut to the axially inner end of the hub ring that protrudes from the axially inner end of the inner ring.

In addition, since the hub unit bearing 1 of this example is a hub unit bearing for a driven wheel, the hub 3 is constructed solidly.

However, the hub unit bearing of the present invention can also be applied to a hub unit bearing for a drive wheel. In this case, the hub has a spline hole in the center that extends through the hub in the axial direction. A distal end portion of a drive shaft, which is rotationally driven by an engine or an electric motor as a drive source, is engaged with the spline hole by a spline. When the automobile is running, the hub is rotationally driven by the drive shaft, thereby rotationally driving the wheels and the braking rotary body that are fixedly connected to the rotating flange of the hub.

The rolling elements 4a, 4b are made of iron alloy 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. It is arranged so that it can freely roll while being held by 19b. Thereby, the hub 3 is rotatably supported inside the outer ring 2 in the radial direction.

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 the present invention is a different diameter PCD type hub unit 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. It can also be applied to bearings. Furthermore, although balls are used as the rolling elements 4a and 4b in the hub unit bearing 1 of this example, tapered rollers may be used instead of the balls.

The sealing device 5 is present between the inner circumferential surface of the outer ring 2 and the outer circumferential surface of the hub 3, and closes an axially outer opening of a rolling element installation space 20 in which the rolling elements 4a and 4b are arranged. As shown in FIG. 2, the seal device 5 includes a sliding ring 21, at least one support bearing 22, a first seal ring 23, and a second seal ring 24.

The sliding ring 21 is arranged around the hub 3 so as not to contact any of the outer ring 2, the hub 3, and the rolling elements 4a and 4b. The sliding ring 21 has an annular shape as a whole, for example, by bending and forming a metal plate such as a stainless steel plate.

In the present invention, although the specific shape of the sliding ring is arbitrary, the sliding ring has at least a radially extending portion, an axially extending portion, and the at least one support bearing on the radially inner side. 22 is arranged. In this example, the sliding ring 21 extends in the axial direction and extends in the radial direction with a curved plate portion 27, a side plate portion 28, an inclined plate portion 29, and an outer collar portion 30, which correspond to portions extending in the radial direction. and a cylindrical portion 25 corresponding to a portion where the at least one support bearing 22 is arranged. In this example, the sliding ring 21 further includes an inner collar portion 26 .

Specifically, the cylindrical portion 25 has a cylindrical shape. The curved plate portion 27 is formed in an annular shape, and is curved in a radially outward direction from the axially outer end of the cylindrical portion 25 toward the axially outer side. The side plate portion 28 is configured in a circular ring shape and extends radially outward from the radially outer end of the curved plate portion 27 . The inclined plate part 29 is configured in a conical tube shape, and is linearly inclined in a direction radially outward as it goes axially inward from the radially outer end of the side plate part 28. The outer flange portion 30 has a circular ring shape and extends from the axially inner end of the inclined plate portion 29 toward the radially outer side. The inward flange 26 has a circular ring shape and extends radially inward from the axially inner end of the cylindrical portion 25 .

The support bearing 22 rotatably supports the sliding ring 21 with respect to the hub 3. In this example, one pair of support bearings 22 is provided. The pair of support bearings 22 are arranged side by side in the axial direction. However, when implementing the present invention, the number of support bearings 22 may be one or three or more.

In the present invention, the type of support bearing is arbitrary, and specifically, whether a rolling bearing or a sliding bearing is adopted, and if a rolling bearing is adopted, whether a bearing ring or a seal ring is provided, and What kind of rolling elements to use is arbitrary. In this example, each of the support bearings 22 constituting the pair of support bearings 22 includes an outer support ring 31, an inner support ring 32, a support outer ring raceway 33 provided on the inner peripheral surface of the support outer ring 31, and an outer periphery of the support inner ring 32. It has a plurality of support rolling elements 35 disposed between a support inner ring raceway 34 provided on the surface. Balls are used as the supporting rolling elements 35. Each of the support outer ring raceway 33 and the support inner ring raceway 34 is constituted by a groove having an arcuate cross-sectional shape. Each of the support bearings 22 constituting the pair of support bearings 22 is connected to an adjacent support of the openings on both sides in the axial direction of the internal space that exists between the inner peripheral surface of the support outer ring 31 and the outer peripheral surface of the support inner ring 32. It has a sliding seal ring 36 that closes the opening on the opposite side of the bearing 22. A radially outer end of the seal ring 36 is locked to an inner circumferential surface of an axial end of the supporting outer ring 31 . The tip of the lip provided at the radially inner end of the seal ring 36 is in sliding contact with the surface of the axial end of the support inner ring 32 .

The support outer rings 31 of the pair of support bearings 22 are fitted inside the sliding ring 21 . Specifically, the support outer rings 31 of the pair of support bearings 22 are fitted into the cylindrical portion of the sliding ring 21 without wobbling in the radial direction. Further, in this state, the support outer ring 31 of the pair of support bearings 22 is held by the inner collar portion 26 and the retaining ring 37 that is locked to the inner peripheral surface of the connection portion between the cylindrical portion 25 and the curved plate portion 27. , are held from both sides in the axial direction. This prevents relative displacement in the axial direction between the support outer ring 31 of the pair of support bearings 22 and the sliding ring 21.

The support inner rings 32 of the pair of support bearings 22 are fitted onto the hub 3 . Specifically, the support inner rings 32 of the pair of support bearings 22 are press-fitted into cylindrical groove shoulders 38 adjacent to the axially outer side of the axially outer inner ring raceway 9a on the outer peripheral surface of the hub 3. It is fitted externally. Further, in this state, the support inner ring 32 of the pair of support bearings 22 is connected to a stepped surface 39 facing axially inward, which is provided at the axially outer end of the groove shoulder 38 of the hub 3. It is held from both sides in the axial direction by a retaining ring 40 that is locked to the axially inner end of the groove shoulder portion 38 . This prevents relative displacement in the axial direction between the support inner ring 32 of the pair of support bearings 22 and the hub 3.

In this example, in this state, the sliding ring 21 is supported by the pair of support bearings 22 such that it can rotate relative to the hub 3 and cannot be displaced relative to the hub 3 in the axial direction. Further, the sliding ring 21 is not in contact with any of the outer ring 2, the hub 3, and the rolling elements 4a. The inner circumferential surface of the axially inner portion of the inclined plate portion 29 of the sliding ring 21 is provided on the outer circumferential surface of the axially outer end of the outer ring 2 and is inclined in a direction in which the diameter becomes smaller toward the axially outer side. It faces the sloped surface portion 41 .

The first seal ring 23 is fixed to the axially outer end of the outer ring 2 and has at least one first seal lip 42 a , 42 b , 42 c whose tip end contacts the surface of the sliding ring 21 . . In this example, the first seal ring 23 has three first seal lips 42a, 42b, and 42c. However, when implementing the present invention, the number of first seal lips may be set to a number other than three.

In this example, the first seal ring 23 includes a core metal 43 and a sealing material 44.

The core metal 43 is formed into an annular shape by bending and forming a metal plate such as a mild steel plate. The core metal 43 is fitted into a seal fitting cylindrical portion 45 that is internally fitted and fixed to the axially outer end of the outer ring 2 by interference fit, and extends radially inward from the axially outer end of the seal fitting cylindrical portion 45. It has a support plate portion 46 that is bent.

The sealing material 44 is made of an elastic material containing an elastomer such as rubber, and is bonded and fixed to the surface of the support plate portion 46 of the core bar 43 by vulcanization adhesive. The sealing material 44 is provided with three first seal lips 42a, 42b, and 42c. The sealing material 44 includes a base 47 in addition to three first sealing lips 42a, 42b, and 42c. Note that, in FIG. 2, each of the first seal lips 42a, 42b, and 42c is shown in a free state.

The base portion 47 covers the surface of the support plate portion 46, specifically, the axially outer surface, the inner circumferential surface, and the radially inner end of the axially inner surface of the support plate portion 46.

Among the three first seal lips 42a, 42b, and 42c, the first seal lip 42a that is the outermost in the radial direction extends from the portion of the base 47 that covers the radially intermediate portion of the axially outer surface of the support plate portion 46. It extends in the direction toward the axially outer side and the radially outer side, and has its tip portion in contact with the axially inner surface of the side plate portion 28 . The second first seal lip 42b from the radially outer side extends in a direction axially outward and radially outward from a portion of the base portion 47 that covers the radially inner end of the support plate portion 46, and The tip portion is brought into contact with the axially inner surface of the curved plate portion 27. The radially innermost first seal lip 42c extends axially inwardly and radially inwardly from the portion of the base portion 47 that covers the radially inner end portion of the support plate portion 46, and has a distal end portion. is brought into contact with the outer peripheral surface of the cylindrical portion 25.

This prevents foreign matter such as muddy water from entering the rolling element installation space 20 from the external space through the space between the sliding ring 21 and the first seal ring 23, and grease sealed in the rolling element installation space 20 from entering the external space. This prevents leakage.

The second seal ring 24 is fixed to the sliding ring 21 and has at least one second seal lip 48 whose tip portion contacts the axially inner surface of the rotating flange 10 . In this example, the second seal ring 24 has one second seal lip 48 . However, when implementing the present invention, the number of second seal lips can also be two or more.

In this example, the second seal ring 24 is made of an elastic material including an elastomer such as rubber, and has an annular shape as a whole. The second seal ring 24 is bonded and fixed to the axially outer surface of the side plate portion 28 of the sliding ring 21 by vulcanization adhesive. The second seal ring 24 includes, in addition to one second seal lip 48 , a base 49 and one auxiliary lip 50 . Note that in FIG. 2, the second seal lip 48 and the auxiliary lip 50 are shown in a free state.

The base portion 49 covers the outer surface of the side plate portion 28 in the axial direction.

The second seal lip 48 extends from the radially inner side of the base portion 49 toward the axially outer side and the radially outer side, and has a tip portion attached to the radially inner end portion of the axially inner side surface of the rotating flange 10. It is brought into contact with the existing flat portion 51. The auxiliary lip 50 extends from the radially outer side of the base portion 49 in the axially outer and radially outward direction, and has its tip end in the radial direction of the flat portion 51 of the axially inner surface of the rotary flange 10. The step portion 52 facing outward in the radial direction, which is present in a portion adjacent to the outside, is closely opposed to the step portion 52 .

This prevents foreign matter such as mud from entering the rolling element installation space 20 from the external space through the space between the sliding ring 21 and the hub 3, and prevents grease sealed in the rolling element installation space 20 from leaking into the external space. It prevents you from doing so. Note that when implementing the present invention, the auxiliary lip can also be omitted.

The hub unit bearing 1 of this example further includes a bottomed cylindrical bearing cap 53 (see FIG. 1) 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 and prevents grease sealed in the rolling element installation space 20 from leaking into the external space through the opening. Note that instead of the bearing cap 53, the opening on the inner side in the axial direction of the rolling element installation space 20 can be closed with a combination seal ring.

In the hub unit bearing 1 of this example, the sliding ring 21 constituting the sealing device 5 is not press-fitted onto the outer peripheral surface of the hub 3, but is rotatable with respect to the hub 3 by a pair of support bearings 22. is supported by In this example, when installing the seal device 5, the sliding ring 21 can be assembled in the following manner, for example. First, the support outer ring 31 of the pair of support bearings 22 is fitted into the cylindrical portion 25 of the sliding ring 21 without radial play, and after fitting, the retaining ring 37 is attached, and the support outer ring 31 is It is clamped from both sides in the axial direction by the inner flange 26 and the retaining ring 37. Next, the support inner rings 32 of the pair of support bearings 22 are press-fitted into the groove shoulders 38 of the hub 3, and the support inner rings 32 are fitted from both sides in the axial direction by the stepped surfaces 39 and the retaining rings 40. to hold.

In this way, unlike the conventional structure, in this example, when installing the sealing device 5, there is no need to expand the diameter of the sliding ring 21 to overcome the convex portion, and a strong force is applied to the sliding ring 21. is not added. Therefore, when installing the seal device 5, it is easy to avoid plastic deformation of the sliding ring 21.

In this example, the friction torque T1 acts on the contact portion between the tips of the first seal lips 42a, 42b, 42c of the first seal ring 23 fixed to the outer ring 2 and the surface of the sliding ring 21, and the sliding ring Friction torque T2 acts on the contact area between the tip of the second seal lip 48 of the second seal ring 24 fixed to the rotary flange 21 and the flat surface 51 of the rotating flange 10, and the seal ring 36 of the pair of support bearings 22 Friction torque T3 acts on the contact portion between the tip of the lip and the surface of the support inner ring 32. The magnitudes of the frictional torques T1, T2, and T3 of the respective contact portions may vary individually based on the occurrence of lip sticking due to temperature changes and pressure changes during operation. In this example, depending on the driving situation, sliding occurs at the contact portion where the magnitude of friction torque T1 and the sum of friction torques T2 and T3 (T2+T3) is smaller; Sliding stops at the contact area where the is larger. Therefore, the sealing torque of the sealing device 5 is the smaller of the friction torque T1 and the sum of the friction torques T2 and T3 (T2+T3). Therefore, it is possible to prevent the sealing torque of the sealing device 5 from increasing.

Furthermore, in this example, relative displacement in the axial direction between the support outer ring 31 and the sliding ring 21 of the pair of support bearings 22 is prevented, and the axial displacement between the support inner ring 32 of the pair of support bearings 22 and the hub 3 is prevented. Relative displacement in the axial direction between the supporting outer ring 31 and the supporting inner ring 32 is prevented based on the engagement between the supporting outer ring raceway 33 and the supporting inner ring raceway 34 and the plurality of supporting rolling elements 35. Displacement is prevented. That is, relative displacement in the axial direction between the sliding ring 21 and the hub 3 is prevented. Therefore, it is possible to prevent the sliding ring 21 from moving excessively inward in the axial direction with respect to the hub 3, thereby preventing the sliding ring 21 from coming into contact with the rolling elements 4a in the axially outer row.

[Second example]
A second example of the embodiment of the present invention will be described using FIG. 4.

In the structure of this example, each of the support bearings 22a constituting the pair of support bearings 22a has a support outer ring raceway 33a provided on the inner peripheral surface of the cylindrical portion 25 of the sliding ring 21a, and a groove shoulder of the hub 3a. 38, and a plurality of supporting rolling elements 35 disposed between the supporting outer ring raceway 33a and the supporting inner ring raceway 34a. Balls are used as the supporting rolling elements 35. Each of the support outer ring raceway 33 and the support inner ring raceway 34 is constituted by a groove having an arcuate cross-sectional shape. Relative displacement in the axial direction between the hub 3a and the sliding ring 21a is prevented based on the engagement of each of the support outer raceway 33 and the support inner raceway 34 with the plurality of support rolling elements 35. In addition, when implementing the present invention, a retainer for retaining the supporting rolling elements 35 may also be provided.

In the structure of this example, the support bearing 22a does not include an outer support ring and an inner support ring as independent components. The sliding ring 21a does not include an inner flange for positioning the supporting outer ring in the axial direction. The hub 3a does not have a stepped surface for positioning the supporting inner ring in the axial direction. In this example, there is no retaining ring for positioning the supporting outer ring and the supporting inner ring in the axial direction. Therefore, production costs can be reduced by reducing the number of parts and the number of processing steps. The other configurations and effects of the second example are the same as those of the first example.

[Third example]
A third example of the embodiment of the present invention will be described using FIG. 5.

In the structure of this example, the support bearing 22b disposed between the groove shoulder portion 38 of the hub 3b and the inner circumferential surface of the cylindrical portion 25 of the sliding ring 21b is a sliding member fixed to the inner circumferential surface of the cylindrical portion 25. Consists of bearings. Specifically, the support bearing 22b is made of a low-friction material such as a slippery synthetic resin and has a cylindrical shape. The outer circumferential surface of the support bearing 22b is bonded and fixed to the inner circumferential surface of the cylindrical portion 25 by adhesive or the like. The inner circumferential surface of the support bearing 22b is fitted onto the groove shoulder portion 38 without any play in the radial direction.

In this example, the retaining ring 40 that is locked to the axially inner end of the groove shoulder 38 is brought into contact with the axially inner end surface of the cylindrical portion 25 of the sliding ring 21b. This prevents the sliding ring 21b from moving axially inward with respect to the hub 3b and causing the axially inner end surface of the cylindrical portion 25 to come into contact with the rolling elements 4a in the axially outer row. ing. Note that when carrying out the present invention, a flange projecting radially outward is provided at the axially inner end of the support bearing 22b, and the axially inner end surface of the cylindrical portion 25 is covered by the flange. You can also do that. The retaining ring 40 can be brought into contact with the axially inner surface of the support bearing 22b provided with the flange.

In this example, a sliding bearing made of a single part is used as the support bearing 22b instead of a rolling bearing made of a plurality of parts, which reduces production costs by reducing the number of parts and making assembly work easier. It is possible to reduce the The other configurations and effects of the third example are the same as those of the first example.

[Fourth example]
A fourth example of the embodiment of the present invention will be described using FIG. 6.

In the structure of this example, compared to the structure of the third example, the retaining ring 40 (see FIG. 5) is omitted to further reduce production costs. In this example, the axial position of the sliding ring 21b is determined by the tension force on the sliding ring 21b of the first seal lips 42a, 42b, 42c forming the first seal ring 23 fixed to the outer ring 2, and the sliding ring 21b. The second seal lip 48 constituting the second seal ring 24 fixed to the second seal ring 21b is automatically adjusted to a position where the tension force against the rotating flange 10 is balanced. Other configurations and effects of the fourth example are the same as those of the third example.

The present invention can be implemented by appropriately combining the structures of the embodiments of the present invention described above to the extent that no contradiction occurs.

1 Hub unit bearing 2 Outer ring 3, 3a, 3b Hub 4a, 4b Rolling element 5 Seal device 6a, 6b Outer ring raceway 7 Stationary flange 8 Support hole 9a, 9b Inner ring raceway 10 Rotating flange 11 Pilot part 12 Mounting hole 13 Stud 14 Inner ring 15 Hub ring 16 Small diameter stepped portion 17 Stepped surface 18 Caulked portion 19a, 19b Cage 20 Rolling element installation space 21, 21a, 21b Sliding ring 22, 22a, 22b Support bearing 23 First seal ring 24 Second seal ring 25 Cylindrical portion 26 Inner collar part 27 Curved plate part 28 Side plate part 29 Inclined plate part 30 Outer collar part 31 Support outer ring 32 Support inner ring 33, 33a Support outer ring raceway 34, 34a Support inner ring raceway 35 Support rolling element 36 Seal ring 37 Retaining ring 38 Groove shoulder Part 39 Step surface 40 Retaining ring 41 Inclined surface portion 42a, 42b, 42c First seal lip 43 Core metal 44 Seal material 45 Seal fitting cylinder portion 46 Support plate portion 47 Base portion 48 Second seal lip 49 Base portion 50 Auxiliary lip 51 Plane portion 52 Stepped portion 53 Bearing cap

Claims (4)

an outer ring having a double-row outer ring raceway on the inner peripheral surface;
a hub having a double-row inner ring raceway on an outer circumferential surface, and a rotating flange protruding radially outward at a portion located axially outer than the outer ring;
a plurality of rolling elements rotatably disposed between the double-row outer ring raceway and the double-row inner ring raceway;
a sealing device that closes an axially outer opening of a rolling element installation space that exists between the inner circumferential surface of the outer ring and the outer circumferential surface of the hub;
The sealing device includes a sliding ring, at least one support bearing, a first sealing ring, and a second sealing ring,
The sliding ring is arranged around the hub so as not to contact any of the outer ring, the hub, and the rolling elements,
The support bearing rotatably supports the sliding ring with respect to the hub,
The first seal ring is fixed to an axially outer end of the outer ring, and has at least one first seal lip whose tip comes into contact with the surface of the sliding ring,
The second seal ring is fixed to the sliding ring and has at least one second seal lip whose tip portion contacts the axially inner surface of the rotating flange.
hub unit bearing. The support bearing includes a support outer ring, a support inner ring, and a support outer ring raceway provided on the inner peripheral surface of the support outer ring and a support inner ring raceway provided on the outer peripheral surface of the support inner ring. It has a supporting rolling element,
The supporting outer ring is fitted into the sliding ring,
the support inner ring is fitted onto the hub;
The hub unit bearing according to claim 1. The support bearing is arranged between a support outer ring raceway provided on the inner peripheral surface of the sliding ring, a support inner ring raceway provided on the outer peripheral surface of the hub, and the support outer ring raceway and the support inner ring raceway. having a plurality of supporting rolling elements,
The hub unit bearing according to claim 1. The hub unit bearing according to claim 1, wherein the support bearing is a sliding bearing fixed to an inner circumferential surface of the sliding ring.

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