Hub unit bearing

Abstract

To provide a hub unit bearing having a seal ring of which two side lips can play respective roles, not only achieving lower torque.SOLUTION: When representing a first side lip 23 and a second side lip 24 in a free state on a cross section cut by a virtual plane including a center axis O of a hub 3, a seal ring 5 has a first bent point 33 located at a position beyond an inclined part 13 in the axial direction and a second bent point 37 located at a position beyond the inclined part 13 in the axial direction. A first axial distance A from the first bent point 33 to an intersection point X1 between the inclined part 13 and the inner peripheral face of a first main part 31 is shorter than a second axial distance B from the second bent point 37 to an intersection point X2 between the inclined part 13 and the inner peripheral face of a second main part 35.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a hub unit bearing. [Background technology]

[0002] Hub unit bearings support the wheels of automobiles so that they can rotate freely relative to the suspension system, and are used in environments where they are directly exposed to muddy water. For this reason, hub unit bearings require high levels of sealing performance. On the other hand, hub unit bearings are also required to keep rotational torque low in order to reduce fuel consumption.

[0003] In a hub unit bearing, a hub to which a wheel is fixed is rotatably supported via multiple rolling elements inside an outer ring supported by a suspension system. A lubricant such as grease is sealed in the annular space in which the rolling elements are installed. The opening of the annular space is sealed with a sealing member such as a seal ring. For this reason, the performance of the sealing member has a significant impact on the sealing performance and torque reduction required of the hub unit bearing.

[0004] FIG. 8 shows a hub unit bearing 100 of a conventional structure described in Japanese Patent Application Laid-Open No. 2016-223453.

[0005] The hub unit bearing 100 has an outer ring 101 and a hub 102. An annular space 103 exists between the inner peripheral surface of the outer ring 101 and the outer peripheral surface of the hub 102, and an opening on the axially outer side of the annular space 103 is closed by a seal ring 104.

[0006] The seal ring 104 is supported and fixed to the outer ring 101. The seal ring 104 has a first side lip 105 that extends in the axial direction, a second side lip 106 that is disposed radially inward of the first side lip 105 and also extends in the axial direction, and a grease lip 107 that extends in the radial direction.

[0007] The hub 102 has a seal sliding surface 108 with which the tip ends of the first side lip 105, the second side lip 106, and the grease lip 107 come into sliding contact.

[0008] The seal sliding surface 108 has a flat portion 109 formed by a circular plane perpendicular to the central axis of the hub 102, an inclined portion 110 formed by an inclined surface that curves in a direction radially outward as it moves away from the annular space 103 in the axial direction, and a cylindrical surface portion 111.

[0009] The first side lip 105 mainly serves to prevent muddy water from entering the annular space 103, and its tip portion is brought into sliding contact with the flat portion 109.

[0010] The second side lip 106 mainly plays a role in preventing the movement of the grease sealed in the space between the second side lip 106 and the first side lip 105 and the grease sealed in the space between the second side lip 106 and the grease lip 107, and its tip is brought into sliding contact with the inclined portion 110.

[0011] The grease lip 107 mainly serves to prevent grease from leaking from the annular space 103 , and its tip portion is brought into sliding contact with the cylindrical surface portion 111 .

[0012] It is generally considered that the shape of a seal lip that serves to prevent the intrusion of muddy water should preferably be one that produces a peak in contact surface pressure on the side where muddy water is entering (the radially outer side).In contrast, the shape of a seal lip that serves to prevent the migration of grease should preferably be one that has a relatively large contact width with the seal sliding surface and produces a gentle distribution of contact surface pressure (no peaks).

[0013] In the conventional structure described in JP 2016-223453 A, the first side lip 105 and the second side lip 106 are provided with a difference in thickness and in the angle of intersection with the seal sliding surface 108, so that the first side lip 105 and the second side lip 106 can obtain contact surface pressures appropriate for their respective roles. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-223453 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-349009 Summary of the Invention [Problem to be solved by the invention]

[0015] In recent years, there has been an increasing demand for lower torque in hub unit bearings, and there is a demand for a seal ring incorporated in the hub unit bearing to have a reduced seal torque.

[0016] Japanese Patent Application Laid-Open No. 2006-349009 describes a technique for reducing the contact width of the side lip with the seal sliding surface to reduce the seal torque caused by the side lip.

[0017] However, in the technology described in JP 2006-349009 A, in order to reduce the sealing torque, a bent portion is provided at the tip of the side lip that is bent radially inward relative to the base end portion, so that the contact surface pressure tends to peak even when the side lip is elastically deformed.

[0018] For this reason, when a bearing has two side lips with different functions, such as the seal ring described in JP 2016-223453 A, the technology described in JP 2006-349009 A can be applied to a side lip that serves to prevent muddy water from entering, but cannot be applied directly to a side lip that serves to prevent grease migration. Specifically, when applied to a side lip that serves to prevent grease migration, the seal torque can be reduced, but conversely, the seal sliding area becomes smaller, making it difficult to prevent grease migration.

[0019] An object of the present disclosure is to provide a hub unit bearing that not only achieves low torque but also allows the two side lips of the seal ring to fully fulfill their respective roles. [Means for solving the problem]

[0020] Each of the hub unit bearings according to one aspect of the present disclosure 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 is supported by the outer ring and closes the opening of an annular space that exists between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub.

[0021] The seal ring has a first side lip extending in the axial direction, and a second side lip located radially inward of the first side lip and extending in the axial direction.

[0022] The first side lip has a first main portion, a first bent portion located further towards the tip than the first main portion and bent radially inward relative to the first main portion, and a first bent point connecting the inner circumferential surface of the first main portion and the inner circumferential surface of the first bent portion.

[0023] The second side lip has a second main portion, a second bent portion located further toward the tip than the second main portion and bent radially inward relative to the second main portion, and a second bending point connecting the inner circumferential surface of the second main portion and the inner circumferential surface of the second bent portion.

[0024] The hub or a member fixed to the hub has a flat portion that is composed of a circular ring-shaped plane perpendicular to the central axis of the hub and against which the first bent portion slides, and an inclined portion that is composed of an inclined surface that slopes curvedly or linearly in a direction radially outward as it approaches the flat portion in the axial direction and against which the second bent portion slides.

[0025] In the hub unit bearing of the first aspect of the present disclosure, when the first side lip and the second side lip are shown in a free state in a cross section cut by an imaginary plane including the center axis of the hub, the first bending point is located at a position beyond the flat portion or the inclined portion in the axial direction, and the second bending point is located at a position beyond the inclined portion in the axial direction, The first axial distance from the first bending point to the intersection of the flat portion or the inclined portion with the inner circumferential surface of the first main portion is shorter than the second axial distance from the second bending point to the intersection of the inclined portion with the inner circumferential surface of the second main portion.

[0026] In a hub unit bearing according to a second aspect of the present disclosure, when the first side lip and the second side lip are shown in a free state in a cross section cut by an imaginary plane including a center axis of the hub, The angle formed between the inner peripheral surface of the first main portion and the inner peripheral surface of the first bent portion is smaller than the angle formed between the inner peripheral surface of the second main portion and the inner peripheral surface of the second bent portion.

[0027] In the hub unit bearing according to one aspect of the present disclosure, the flat portion and the inclined portion can be provided directly on the hub. Alternatively, the flat portion and the inclined portion may be provided on a member fixed to the hub. In this case, the flat portion and the inclined portion may be provided on a slinger fixed to the hub. [Effects of the Invention]

[0028] According to the hub unit bearing according to one aspect of the present disclosure, not only can low torque be achieved, but the two side lips of the seal ring can also fully fulfill their respective roles. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a cross-sectional view showing a hub unit bearing according to a first example of an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged view corresponding to the portion α in FIG. 1, and shows the first side lip, the second side lip and the grease lip provided on the seal ring in a free state. [Figure 3] FIG. 3 is a partially enlarged view of FIG. [Figure 4] FIG. 4 is an enlarged view corresponding to the portion α in FIG. 1, showing the first side lip, the second side lip and the grease lip provided on the seal ring in an elastically deformed state. [Figure 5] FIG. 5 is a cross-sectional view showing a seal ring that closes an axially inner opening of the annular space according to a second embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram corresponding to FIG. 2 and showing a third example of an embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram corresponding to FIG. 2 and showing a fourth example of an embodiment of the present disclosure. [Figure 8] FIG. 8 is a partial cross-sectional view showing a hub unit bearing of a conventional structure. DETAILED DESCRIPTION OF THE INVENTION

[0030] [Example 1] A first example of an embodiment of the present disclosure will be described with reference to FIGS.

[0031] This example shows an example in which the seal ring of the hub unit bearing according to the first aspect of the present disclosure is applied to a seal ring that closes an opening on the axially outer side of the annular space.

[0032] [Overall structure of hub unit bearing] The hub unit bearing 1 includes an outer ring 2, a hub 3, a plurality of rolling elements 4a, 4b, and a seal ring 5. The hub unit bearing 1 is an inner ring rotating type hub unit bearing.

[0033] The hub unit bearing 1 of this example is a so-called third-generation hub unit bearing for a driven wheel. However, a hub unit bearing according to one embodiment of the present disclosure can also be applied to hub unit bearings for driving wheels, as well as first- and second-generation hub unit bearings.

[0034] In the following description, unless otherwise specified, the axial direction, radial direction, and circumferential direction of the hub unit bearing 1 refer to the axial direction, radial direction, and circumferential direction of the outer ring 2. The axial direction, radial direction, and circumferential direction of the outer ring 2 coincide with the axial direction, radial direction, and circumferential direction of the hub 3. Additionally, the outer axial direction refers to the outer side in the width direction of the vehicle when the hub unit bearing 1 is assembled to the vehicle, and the inner axial direction refers to the center side in the width direction of the vehicle when the hub unit bearing 1 is assembled to the vehicle.

[0035] The outer ring 2 is made of a hard metal such as medium carbon steel, and has double-row outer ring raceways 6a and 6b on its inner circumferential surface.

[0036] The outer ring 2 has a stationary flange 7 that protrudes radially outward from an axially intermediate portion. The stationary flange 7 is a portion used to connect and fix the outer ring 2 to a knuckle of a suspension system. In use, the outer ring 2 is connected and fixed to the knuckle of the suspension system and does not rotate.

[0037] The hub 3 is made of a hard metal such as medium carbon steel or bearing steel, and has double-row inner ring raceways 8a, 8b on its outer peripheral surface, and a rotating flange 9 that protrudes radially outward at a portion axially outer than the outer ring 2, and is disposed radially inside and coaxial with the outer ring 2. The rotating flange 9 is a part used to connect and fix a wheel and a rotating braking member to the hub 3.

[0038] The hub 3 has a cylindrical pilot portion 10 at its axially outer end. The pilot portion 10 is a portion onto which a wheel and a rotating braking member that are coupled and fixed to the rotating flange 9 are fitted. When in use, the hub 3 rotates integrally with the wheel and the rotating braking member that are coupled and fixed to the rotating flange 9.

[0039] The hub 3 or a member fixed to the hub 3 has a seal sliding contact surface 11 that functions as a sliding contact surface for the seal ring 5. In this example, the seal sliding contact surface 11 is provided directly on the hub 3.

[0040] However, when implementing a hub unit bearing according to one aspect of the present disclosure, the seal sliding surface may be provided on a member that is fixed to the hub and rotates in synchronization with the hub, such as a sliding ring or slinger.

[0041] The seal sliding surface 11 is configured to include a flat portion 12 and an inclined portion 13. Therefore, the flat portion 12 and the inclined portion 13 are provided directly on the hub 3.

[0042] The flat surface portion 12 is formed by a circular flat surface that is perpendicular to the central axis O (see FIG. 1) of the hub 3. In this example, the flat surface portion 12 is provided on the axially inner surface of the radially inner end portion of the rotating flange 9. A tip end portion (first bent portion 32) of a first side lip 23 (described below) that constitutes the seal ring 5 is brought into sliding contact with the flat surface portion 12.

[0043] The inclined portion 13 is configured as an inclined surface that is curved or linearly inclined in a direction radially outward as it approaches the flat portion 12 in the axial direction. In this example, the inclined portion 13 is configured as a concave curved surface that is curved and inclined in a direction radially outward as it approaches the flat portion 12 in the axial direction (as it moves axially outward). Therefore, the inclined portion 13 has an arc-shaped cross section. The axially outer end of the inclined portion 13 is connected to the radially inner end of the flat portion 12. The tip end (second bent portion 36) of the second side lip 24 (described later) that constitutes the seal ring 5 is brought into sliding contact with the inclined portion 13.

[0044] In this example, the seal sliding contact surface 11 further includes a cylindrical surface portion 14 .

[0045] The cylindrical surface portion 14 is formed by a cylindrical surface whose outer diameter does not change in the axial direction. The cylindrical surface portion 14 is provided on the outer peripheral surface of a portion of the hub 3 that is adjacent to the axially outer side of the axially outer inner ring raceway 8a. The axially outer end of the cylindrical surface portion 14 is connected to the axially inner end of the inclined portion 13. The tip end of a grease lip 39 (described below) that constitutes the seal ring 5 is brought into sliding contact with the cylindrical surface portion 14.

[0046] In this example, the hub 3 is configured by combining a hub ring 15 and an inner ring 16. However, when implementing the hub unit bearing of the present disclosure, the hub may be configured by a combination of parts different from those in this example.

[0047] The hub ring 15 comprises an inner ring raceway 8 a on the axially outer side, a rotation flange 9 , a pilot portion 10 , a flat portion 12 , an inclined portion 13 , and a cylindrical surface portion 14 that constitute the hub 3 .

[0048] The hub ring 15 has a small diameter step 17 at a portion axially more inward than the axially outer inner ring raceway 8a, the small diameter step 17 having an outer diameter smaller than the portion adjacent to it on the axially outer side, onto which the inner ring 16 is fitted. Furthermore, the hub ring 15 has a step surface 18 facing axially inward at the axially outer end of the small diameter step 17, and a crimped portion 19 bent radially outward from the axially inner end of the small diameter step 17.

[0049] The inner ring 16 has an inner ring raceway 8b on the axially inner side, which constitutes the hub 3, on its outer peripheral surface.

[0050] In this example, the hub 3 is constructed by fitting an inner ring 16 onto the axially inner portion of the hub wheel 15. More specifically, in this example, the hub 3 is constructed by fitting the inner ring 16 onto the small diameter step 17 of the hub wheel 15, and then clamping the inner ring 16 from both axial sides between the step surface 18 of the hub wheel 15 and a crimped portion 19, thereby joining and fixing the hub wheel 15 and the inner ring 16 together. Note that the crimped portion 19 is formed by plastically deforming a cylindrical portion provided at the axially inner end of the hub wheel 15 radially outward after the inner ring 16 has been fitted onto the small diameter step 17.

[0051] Alternatively, the hub wheel and the inner ring can be joined by threading a nut onto the axially inner end of the hub wheel that protrudes from the axially inner end of the inner ring.

[0052] Since the hub unit bearing 1 of this example is a hub unit bearing for a driven wheel, the hub 3 is constructed to be solid.

[0053] However, the hub unit bearing of the present disclosure can also be applied to a hub unit bearing for a drive wheel. In this case, the hub has a spline hole that penetrates axially in the center. The tip of a drive shaft that is driven to rotate by an engine or electric motor as a drive source is spline-engaged with the spline hole. When the vehicle is running, the hub is driven to rotate by the drive shaft, which in turn drives to rotate the wheel and braking rotating member that are coupled and fixed to the rotating flange of the hub.

[0054] The rolling elements 4a, 4b are made of an 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 8a, 8b, with a plurality of rolling elements on each side held by cages 20a, 20b, so that the hub 3 is rotatably supported radially inside the outer ring 2.

[0055] The hub unit bearing 1 of this example has a so-called equal diameter PCD type structure, in which the pitch diameter of the rolling elements 4a in the axially outer row is equal to the pitch diameter of the rolling elements 4b in the axially inner row. However, the hub unit bearing of the present disclosure can also be applied to a so-called different diameter PCD type hub unit bearing, in which the pitch diameter of the rolling elements in the axially outer row is different from the pitch diameter of the rolling elements 4b in the axially inner row. Also, while the hub unit bearing 1 of this example uses balls as the rolling elements 4a, 4b, tapered rollers can also be used instead of balls.

[0056] The seal ring 5 is supported by the outer ring 2 and closes the opening of an annular space 21 that exists between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3. In this example, the seal ring 5 closes the opening on the axial outer side of the annular space 21. This prevents foreign matter from the external space from entering the annular space 21 through the opening on the axial outer side of the annular space 21 and prevents lubricant such as grease sealed in the annular space 21 from leaking into the external space.

[0057] However, when implementing the hub unit bearing according to the first aspect of the present disclosure, the seal ring can also block the axially inner opening of the annular space in addition to or instead of the axially outer opening of the annular space.

[0058] The hub unit bearing 1 of this example further includes a bearing cap 22 that closes the axially inner opening of the annular space 21. This prevents foreign matter from the external space from entering the annular space 21 through the axially inner opening of the annular space 21 and prevents the lubricant sealed in the annular space 21 from leaking into the external space. When implementing a hub unit bearing according to one aspect of the present disclosure, openings other than the opening closed by the seal ring according to one aspect of the present disclosure can be closed not only by bearing caps but also by sealing devices such as combination seal rings.

[0059] [Seal ring structure] The structure of the seal ring 5 will be described with reference to FIGS.

[0060] Figure 2 is a diagram showing the first side lip 23, second side lip 24 and grease lip 39 provided on the seal ring 5 in a free state in a cross section cut on an imaginary plane including the center axis O of the hub 3, Figure 3 is a partially enlarged view of Figure 2, and Figure 4 is a diagram showing the first side lip 23, second side lip 24 and grease lip 39 in an elastically deformed state in a cross section cut on an imaginary plane including the center axis O of the hub 3.

[0061] The seal ring 5 has a first side lip 23 that extends in the axial direction and a second side lip 24 that is located radially inward of the first side lip 23 and also extends in the axial direction. That is, the seal ring 5 has two side lips 23, 24. When implementing a hub unit bearing according to one aspect of the present disclosure, the seal ring may have two or more side lips.

[0062] In this example, the seal ring 5 is made up of a core metal 25 and a seal member 26 having a first side lip 23 and a second side lip 24.

[0063] The core metal 25 is made of a metal plate such as a cold-rolled steel plate, and is configured in an annular shape as a whole.

[0064] The core wire 25 has a cylindrical fitting tube portion 27, a circular ring-shaped outward flange portion 28 that is bent radially outward from the axially outer end of the fitting tube portion 27, and an inward flange portion 29 whose radially outer end is connected to the axially inner end of the fitting tube portion 27 and has an approximately crank-shaped cross-sectional shape.

[0065] The core metal 25 is supported and fixed to the outer ring 2 by fitting the fitting tubular portion 27 tightly into the axially outer end portion of the outer ring 2. The axially inner surface of the outward flange portion 28 abuts against the axially outer end face of the outer ring 2.

[0066] The seal member 26 is made of an elastic material such as an elastomer containing rubber, and is configured in an annular shape as a whole. The seal member 26 is bonded and fixed to the core metal 25.

[0067] The seal member 26 has a seal base 30 in addition to the first side lip 23 and the second side lip 24 .

[0068] The seal base 30 covers the surface of the core metal 25. Specifically, the seal base 30 covers the inner peripheral surface of the fitting cylindrical portion 27, the axially outer side surface of the outward flange portion 28, the radially outer end of the axially inner side surface, and the outer peripheral surface, and also covers the axially outer side surface of the inward flange portion 29, the radially inner portion of the axially inner side surface, and the inner peripheral surface.

[0069] The first side lip 23 and the second side lip 24 are contact lips whose tip portions are brought into contact with the seal sliding contact surface 11. The first side lip 23 and the second side lip 24 are arranged to overlap in the radial direction.

[0070] In the free state of the first side lip 23 and the second side lip 24, the tip end of the first side lip 23 is located axially outward of the tip end of the second side lip 24. In this example, the base end of the first side lip 23 and the base end of the second side lip 24 are located at approximately the same axial position, so that the axial dimension of the first side lip 23 is larger than the axial dimension of the second side lip 24 in the free state.

[0071] The first side lip 23 is the contact lip provided on the seal ring 5 closest to the external space, and its main role is to prevent muddy water from entering the annular space 21.

[0072] The first side lip 23 has a generally partial conical cylindrical shape in a free state. The base end of the first side lip 23 is connected to the axially outer surface of the radially inner portion of the seal base 30, and extends radially outward as it moves axially outward. The tip of the first side lip 23 slides against the flat surface 12 provided on the hub 3. As shown in FIG. 4 , with the tip of the first side lip 23 in sliding contact with the flat surface 12, the first side lip 23 elastically deforms so that its middle portion convex radially inward.

[0073] The first side lip 23 has a first main portion 31, a first bent portion 32 located further towards the tip than the first main portion 31 and bent radially inward relative to the first main portion 31, and a first bent point 33 connecting the inner circumferential surface of the first main portion 31 and the inner circumferential surface of the first bent portion 32.

[0074] The first main portion 31 constitutes the range from the base end to the middle portion of the first side lip 23. Therefore, the axially inner end of the first main portion 31 is connected to the axially outer surface of the radially inner portion of the seal base 30. In the free state of the first side lip 23, the first main portion 31 has a partially conical cylindrical shape, with inner and outer circumferential surfaces each shaped like a truncated cone (tapered surface). The thickness of the first main portion 31 gradually increases from the axially inner side toward the axially outer side, or is constant throughout its entire length.

[0075] The first bent portion 32 forms the tip end of the first side lip 23. When the first side lip 23 is in a free state, the first bent portion 32 has a partially conical cylindrical shape, each having a truncated cone-shaped inner circumferential surface, an outer circumferential surface, and an axially outer end face. The thickness of the first bent portion 32 is substantially constant over its entire length.

[0076] When the first side lip 23 is in a free state, the inclination angle of the first bent portion 32 relative to the central axis O of the hub 3 is smaller than the inclination angle of the first main portion 31 relative to the central axis O of the hub 3. The inclination direction of the first bent portion 32 relative to the central axis O of the hub 3 and the inclination direction of the first main portion 31 relative to the central axis O of the hub 3 are the same.

[0077] In the free state of the first side lip 23, the axial dimension L of the inner circumferential surface of the first bent portion 32 32 is the axial dimension L of the inner circumferential surface of the first main portion 31 31 is much shorter than (L 32 <L 31 Specifically, the axial dimension L of the inner peripheral surface of the first bent portion 32 32In order to suppress the elastic deformation of the first bent portion 32 and maintain the shape, the axial dimension L of the inner circumferential surface of the first main portion 31 is 31 In this example, the thickness of the first bent portion 32 is approximately the same as the thickness of the first main portion 31.

[0078] The first bent portion 32 has a first ridge portion 34 connecting the inner peripheral surface and the axially outer end face. The angle formed by the inner peripheral surface of the first bent portion 32 and the axially outer end face is preferably an acute angle or a right angle, and is preferably between 70 degrees and 80 degrees, from the viewpoint of preventing the first bent portion 32 from falling while suppressing the contact width between the first ridge portion 34 and the seal contact surface 11 (flat portion 12).

[0079] In the free state of the first side lip 23, the first bending point 33 is located at a position beyond (passing through) the flat portion 12 or the inclined portion 13 in the axial direction. In this example, the first bending point 33 is located at a position beyond the inclined portion 13 in the axial direction, i.e., axially outward of the inclined portion 13. Therefore, the inner circumferential surface of the first main portion 31 intersects with the inclined portion 13 at an intersection point X1. However, when implementing a hub unit bearing according to one aspect of the present disclosure, the first bending point may be located at a position beyond the flat portion in the axial direction. In this case, the inner circumferential surface of the first main portion intersects with the flat portion.

[0080] The second side lip 24 is a contact lip disposed radially inward of the first side lip 23, which is the radially outermost contact lip among the contact lips provided on the seal ring 5, and its main role is to prevent the movement of grease. Specifically, the second side lip 24 mainly plays a role in preventing the movement of grease sealed in the space between the second side lip 24 and the first side lip 23 and the space between the second side lip 24 and a grease lip 39 (described later).

[0081] The second side lip 24 has a generally partial conical cylindrical shape in a free state. The base end of the second side lip 24 is connected to the inner peripheral surface of the seal base 30, and extends radially outward as it moves axially outward. The tip of the second side lip 24 slides against the inclined portion 13 provided on the hub 3. As shown in FIG. 4 , with the tip of the second side lip 24 in sliding contact with the inclined portion 13, the second side lip 24 elastically deforms so that its middle portion convex radially inward.

[0082] The second side lip 24 has a second main portion 35, a second bent portion 36 located further towards the tip than the second main portion 35 and bent radially inward relative to the second main portion 35, and a second bend point 37 connecting the inner circumferential surface of the second main portion 35 and the inner circumferential surface of the second bent portion 36.

[0083] The second main portion 35 constitutes the range from the base end to the middle portion of the second side lip 24. Therefore, the axially inner end of the second main portion 35 is connected to the inner circumferential surface of the seal base 30. In the free state of the second side lip 24, the second main portion 35 has a partially conical cylindrical shape, with inner and outer circumferential surfaces each shaped like a truncated cone. The thickness of the second main portion 35 gradually increases from the axially inner side to the axially outer side, or is constant throughout its entire length.

[0084] The second bent portion 36 forms the tip end of the second side lip 24. When the second side lip 24 is in a free state, the second bent portion 36 has a partially conical cylindrical shape, each having a truncated cone-shaped inner circumferential surface, an outer circumferential surface, and an axially outer end face. The thickness of the second bent portion 36 is substantially constant over its entire length.

[0085] When the second side lip 24 is in a free state, the inclination angle of the second bent portion 36 relative to the central axis O of the hub 3 is smaller than the inclination angle of the second main portion 35 relative to the central axis O of the hub 3. The inclination direction of the second bent portion 36 relative to the central axis O of the hub 3 and the inclination direction of the second main portion 35 relative to the central axis O of the hub 3 are the same. Furthermore, when the two side lips 23, 24 are in a free state, the inclination angle of the second main portion 35 relative to the central axis O of the hub 3 is smaller than the inclination angle of the first main portion 31 relative to the central axis O of the hub 3.

[0086] When the second side lip 24 is in a free state, the axial dimension L of the inner circumferential surface of the second bent portion 36 36 is the axial dimension L of the inner circumferential surface of the second main portion 35 35 is much shorter than (L 36 <L 35 Specifically, the axial dimension L of the inner peripheral surface of the second bent portion 36 36 For the same reason as the first side lip 23, the axial dimension L of the inner peripheral surface of the second main portion 35 is 35 In this example, the thickness of the second bent portion is approximately the same as the thickness of the second main portion .

[0087] In this example, the axial dimension L of the inner circumferential surface of the second main portion 35 35 is the axial dimension L of the inner circumferential surface of the first main portion 31 31 shorter than (L 35 <L 31 The axial dimension L of the inner peripheral surface of the second bent portion 36 36 is the axial dimension L of the inner circumferential surface of the first bent portion 32 32 shorter than (L 36 <L 32 The thickness of the second main portion 35 is approximately the same as or smaller than the thickness of the first main portion 31. The thickness of the second bent portion 36 is approximately the same as or smaller than the thickness of the first bent portion 32.

[0088] The second bent portion 36 has a second ridge portion 38 connecting the inner circumferential surface and the axially outer end face. The angle formed by the inner circumferential surface of the second bent portion 36 and the axially outer end face is preferably an acute angle, and is preferably between 65 degrees and 75 degrees, in order to absorb changes in the contact angle of the second ridge portion 38 due to variations in the contact position between the second ridge portion 38 and the inclined portion 13 caused by variations in the length of the second side lip 24.

[0089] In the free state of the second side lip 24, the second bending point 37 is located beyond (passes through) the inclined portion 13 in the axial direction, i.e., is located axially outward of the inclined portion 13. The inner circumferential surface of the second main portion 35 intersects with the inclined portion 13 at an intersection X2.

[0090] As described above, in the free state of the first side lip 23 and the second side lip 24, the first bending point 33 is located beyond the inclined portion 13 in the axial direction, and the second bending point 37 is located beyond the inclined portion 13 in the axial direction. The first axial distance A from the first bending point 33 to the intersection X1 between the inclined portion 13 and the inner circumferential surface of the first main portion 31 is shorter than the second axial distance B from the second bending point 37 to the intersection X2 between the inclined portion 13 and the inner circumferential surface of the second main portion 35 (first axial distance A<second axial distance B). Note that when the first bending point is located beyond the flat portion in the axial direction, the first axial distance is the distance from the first bending point to the intersection between the flat portion and the inner circumferential surface of the first main portion, and this distance (first axial distance) is shorter than the second axial distance.

[0091] The first axial distance A is preferably 10% to 30% of the second axial distance B. In this example, the first axial distance A is the axial dimension L of the inner circumferential surface of the first bent portion 32. 32 The second axial distance B is sufficiently smaller than the axial dimension L of the inner circumferential surface of the second bent portion 36. 36 It is about the same as

[0092] In this example, the seal material 26 of the seal ring 5 further has a grease lip 39, a dam portion 40, and an eaves lip 41. When implementing a hub unit bearing according to one aspect of the present disclosure, it is optional for the seal ring to have a grease lip, a dam portion, and an eaves lip.

[0093] The grease lip 39 is the contact lip provided on the seal ring 5 closest to the annular space 21, and its main role is to prevent grease from leaking from the annular space 21.

[0094] The grease lip 39 has a generally partial conical cylindrical shape in a free state. The base end of the grease lip 39 is connected to the inner circumferential surface of the seal base 30, and extends radially inward as it moves axially inward. The tip of the grease lip 39 is in sliding contact with the cylindrical surface portion 14 provided on the hub 3.

[0095] The dam portion 40 has a disk shape, and its radially inner end is connected to the radially outer end of the seal base 30. The dam portion 40 has an outer diameter larger than the outer peripheral surface of the axially outer end of the outer ring 2. The dam portion 40 serves to prevent foreign matter, such as muddy water, that flows along the outer peripheral surface of the outer ring 2 from reaching the first side lip 23.

[0096] The eaves lip 41 is a non-contact lip (labyrinth lip). The eaves lip 41 has a partially conical cylindrical shape, and its base end is connected to the axially outer surface of the radially outer end of the seal base 30. The eaves lip 41 has its tip end closely facing a portion of the axially inner surface of the rotating flange 9 that is located radially outward of the flat portion 12, forming a labyrinth seal between itself and the axially inner surface of the rotating flange 9. The eaves lip 41 serves to prevent foreign matter such as muddy water from splashing directly onto the first side lip 23.

[0097] According to the hub unit bearing 1 of this embodiment, not only can low torque be achieved, but the two side lips 23, 24 of the seal ring 5 can also fully fulfill their respective roles.

[0098] That is, as shown in Figure 3, when the seal ring 5 of this example is shown in a cross section cut by an imaginary plane including the center axis O of the hub 3, with the first side lip 23 and the second side lip 24 in a free state, the first bending point 33 is located at a position beyond the flat portion 12 or the inclined portion 13 in the axial direction, and the second bending point 37 is located at a position beyond the inclined portion 13 in the axial direction, and the first axial distance A from the first bending point 33 to the intersection X1 between the flat portion 12 or the inclined portion 13 and the inner surface of the first main portion 31 is shorter than the second axial distance B from the second bending point 37 to the intersection X2 between the inclined portion 13 and the inner surface of the second main portion 35 (first axial distance A < second axial distance B).

[0099] The first side lip 23 has its tip, the first bent portion 32, in sliding contact with the flat portion 12, which is formed by a circular flat surface. Therefore, the first axial distance A is set shorter than the second axial distance B. Therefore, in an elastically deformed state, the intersection angle between the inner circumferential surface of the first bent portion 32 and the flat portion 12 is large. Therefore, a peak in contact pressure is likely to occur at the sliding contact portion between the first bent portion 32 and the flat portion 12, on the side from which muddy water penetrates. Specifically, the first ridge portion 34 of the first bent portion 32 and a portion of the inner circumferential surface near the first ridge portion 34 are in sliding contact with the flat portion 12, so a peak in contact pressure is likely to occur at the contact portion between the first ridge portion 34 and the flat portion 12. Therefore, the first side lip 23 can adequately perform its role of preventing muddy water from penetrating. Furthermore, the contact width between the first bent portion 32 and the flat portion 12 is sufficiently small, thereby suppressing the sealing torque of the first side lip 23.

[0100] The second side lip 24 has its tip, the second bent portion 36, in sliding contact with the inclined portion 13, which is formed by an inclined surface. Therefore, by setting the second axial distance B longer than the first axial distance A, the amount of elastic deformation of the second side lip 24 increases, and the intersection angle between the inner circumferential surface of the second bent portion 36 and the inclined portion 13 decreases. This increases the contact width between the second bent portion 36 and the inclined portion 13 to a certain extent. Specifically, a relatively wide area of ​​the second bent portion 36, including the second ridge portion 38 and the inner circumferential surface near the second ridge portion 38, is in sliding contact with the inclined portion 13 due to elastic deformation. Therefore, the contact pressure distribution at the sliding contact portion between the second bent portion 36 and the inclined portion 13 is gentle (trapezoidal, plateau-like). Therefore, the second side lip 24 can adequately prevent grease migration. Furthermore, the second side lip 24 has a smaller contact width with the inclined portion 13 than when the second bent portion 36 is not provided at the tip thereof, so the sealing torque of the second side lip 24 is kept low.

[0101] As a result, according to the hub unit bearing 1 of this embodiment, not only can low torque be achieved, but the two side lips 23, 24 of the seal ring 5 can also fully fulfill their respective roles.

[0102] Furthermore, in this example, the seal ring 5 is provided with the weir portion 40, which prevents foreign matter such as muddy water flowing along the outer peripheral surface of the outer ring 2 from reaching the first side lip 23. In addition, the seal ring 5 is provided with the eaves lip 41, which prevents foreign matter such as muddy water from directly splashing onto the first side lip 23. Therefore, the sealing performance of the seal ring 5 is sufficiently improved.

[0103] [Example 2] A second example of the embodiment of the present disclosure will be described with reference to FIG.

[0104] This example shows an example in which the seal ring of the hub unit bearing according to the first aspect of the present disclosure is applied to a seal ring that closes an axially inner opening of an annular space.

[0105] FIG. 5 is a cross-sectional view taken along an imaginary plane including the central axis O of the hub 3 (see FIG. 1), showing the first side lip 23 and the second side lip 24 provided on the seal ring 5a in a free state.

[0106] The seal ring 5a of this example is combined with a slinger 42 to form a combined seal ring 43, which closes the opening of the annular space 21 on the axially inner side.

[0107] The slinger 42 is a member fixed to the hub 3. In this example, the slinger 42 is externally fitted and fixed to the inner ring 16 that constitutes the hub 3 by an interference fit, and rotates in synchronization with the hub 3.

[0108] In this example, the slinger 42 is configured solely from a core made of a rust-resistant metal plate such as ferritic stainless steel plate (SUS430) or austenitic stainless steel plate (SUS304), and is configured in an annular shape as a whole. However, when implementing a hub unit bearing according to one aspect of the present disclosure, the slinger that forms a combined seal ring together with the seal ring can also be configured from a core and an encoder.

[0109] The slinger 42 has a seal sliding surface 11a. The seal sliding surface 11a is configured with a flat portion 12a that is formed of a circular flat surface perpendicular to the central axis O of the hub 3 and with which the first bent portion 32 slides, and an inclined portion 13a that is formed of an inclined surface that is curved or linearly inclined in a direction radially outward as it approaches the flat portion 12a in the axial direction and with which the second bent portion 36 slides.

[0110] In this example, the inclined portion 13a is configured by a tapered surface that is an inclined surface that is linearly inclined in a direction that goes radially outward as it approaches the flat portion 12a in the axial direction.

[0111] In this example, the seal sliding contact surface 11a further includes a cylindrical surface portion 14a. The cylindrical surface portion 14a is configured by a cylindrical surface whose outer diameter does not change in the axial direction.

[0112] The radially inner end of the flat portion 12a is connected to the axially inner (radially outer) end of the inclined portion 13a, and the axially outer (radially inner) end of the inclined portion 13a is connected to the axially inner end of the cylindrical surface portion 14a.

[0113] The structure and role of the first side lip 23 and second side lip 24 provided on the seal ring 5a are the same as the structure and role of the first side lip 23 and second side lip 24 provided on the seal ring 5 of the first example.

[0114] In this example, the first side lip 23 has its tip, the first bent portion 32, in sliding contact with the flat portion 12a of the slinger 42. The second side lip 24 has its tip, the second bent portion 36, in sliding contact with the inclined portion 13a of the slinger 42.

[0115] In the free state of the first side lip 23, the first bending point 33 is located beyond the flat portion 12a in the axial direction, and in the free state of the second side lip 24, the second bending point 37 is located beyond the inclined portion 13a in the axial direction. A first axial distance A from the first bending point 33 to an intersection X1 between the flat portion 12a and the inner circumferential surface of the first main portion 31 is shorter than a second axial distance B from the second bending point 37 to an intersection X2 between the inclined portion 13a and the inner circumferential surface of the second main portion 35 (first axial distance A<second axial distance B). Note that the first bending point may be located beyond the inclined portion in the axial direction. In this case, the first axial distance is the distance from the first bending point to the intersection between the inclined portion and the inner circumferential surface of the first main portion, and this distance (first axial distance) is shorter than the second axial distance.

[0116] The seal ring 5a is composed of a core metal 25a and a seal member 26a having a first side lip 23 and a second side lip 24.

[0117] The core wire 25a has an approximately L-shaped cross section and is composed of a cylindrical fitting tube portion 27a and an inward flange portion 29a that is bent at approximately a right angle from the axially outer end of the fitting tube portion 27a toward the radially inner side.

[0118] The core metal 25a is supported and fixed to the outer ring 2 by fitting the fitting cylindrical portion 27a into the axially inner end of the outer ring 2 by interference fit.

[0119] The seal member 26 a has a seal base 30 a and a grease lip 39 in addition to the first side lip 23 and the second side lip 24 .

[0120] The seal base 30a covers the surface of the core metal 25a. Specifically, the seal base 30a covers the inner peripheral surface, the axially inner end portion and the axially inner end face of the outer peripheral surface of the fitting cylindrical portion 27a, and also covers the axially inner side surface, the radially inner portion of the axially outer surface and the inner peripheral surface of the inward flange portion 29a.

[0121] The base end of the grease lip 39 is connected to the inner circumferential surface of the seal base 30a, and extends radially inward and axially outward. The tip of the grease lip 39 is in sliding contact with the cylindrical surface portion 14a provided on the slinger 42.

[0122] In the case of the hub unit bearing 1 of this example equipped with the seal ring 5a as described above, not only can torque be reduced, but the two side lips 23, 24 equipped on the seal ring 5a can also fully fulfill their respective roles.

[0123] Other configurations and effects of the second example are the same as those of the first example.

[0124] [Example 3] A third example of the embodiment of the present disclosure will be described with reference to FIG.

[0125] This example shows an example in which the seal ring of the hub unit bearing according to the second aspect of the present disclosure is applied to a seal ring that blocks the axially outer opening of the annular space. However, when implementing the hub unit bearing according to the second aspect of the present disclosure, the seal ring can also block the axially outer opening of the annular space in addition to or instead of the axially inner and outer openings of the annular space.

[0126] The hub unit bearing 1a of this example has the same structure as the hub unit bearing 1 of the first example, except for the first side lip 23a and second side lip 24a that make up the seal ring 5b. For this reason, explanation of the parts of the hub unit bearing 1a other than the first side lip 23a and second side lip 24a will be omitted. Furthermore, the basic structure and role of the first side lip 23a and second side lip 24a are the same as the basic structure and role of the first side lip 23 and second side lip 24 of the first example, so redundant explanations will be omitted and the explanation will focus on the parts that differ from the first side lip 23 and second side lip 24 of the first example.

[0127] In this example, when the seal ring 5b is shown in a cross section cut by a virtual plane including the center axis O of the hub 3 (see Figure 1), with the first side lip 23a and the second side lip 24a in a free state, the angle θ1 between the inner surface of the first main portion 31a and the inner surface of the first bent portion 32a is smaller than the angle θ2 between the inner surface of the second main portion 35a and the inner surface of the second bent portion 36a (θ1 < θ2).

[0128] The difference between angle θ2 and angle θ1 is preferably 5 degrees or more and 20 degrees or less, taking into consideration the difference between the tangent angle of inclined surface 13 at the position where first edge 34a contacts and the tangent angle of inclined surface 13 at the position where second edge 38a contacts. Angle θ1 is preferably 150 degrees or more and 170 degrees or less. Angle θ2 is preferably 160 degrees or more and 180 degrees or less.

[0129] In this example, when the first side lip 23a and the second side lip 24a are in a free state, the first bending point 33a is located at a position beyond the inclined portion 13 (or the flat portion 12) in the axial direction, and the second bending point 37a is located at a position beyond the inclined portion 13 in the axial direction. However, in the seal ring 5b of this example, it is optional for the first bending point 33a to be located at a position beyond the inclined portion 13 (or the flat portion 12) in the axial direction, and for the second bending point 37a to be located at a position beyond the inclined portion 13 in the axial direction.

[0130] In this example, a first axial distance A (not shown) from the first bending point 33a to an intersection X1 between the inclined portion 13 (or the flat portion 12) and the inner circumferential surface of the first main portion 31a is shorter than a second axial distance B (not shown) from the second bending point 37a to an intersection X2 between the inclined portion 13 and the inner circumferential surface of the second main portion 35a. However, in the seal ring 5b of this example, it is optional for the first axial distance A to be shorter than the second axial distance B.

[0131] According to the hub unit bearing 1a of this embodiment, not only can low torque be achieved, but the two side lips 23a, 24a of the seal ring 5b can also fully fulfill their respective roles.

[0132] That is, in the seal ring 5b of this example, when the first side lip 23a and the second side lip 24a are shown in a free state in a cross section cut by an imaginary plane including the center axis O of the hub 3, the angle θ1 formed between the inner surface of the first main portion 31a and the inner surface of the first bent portion 32a is smaller than the angle θ2 formed between the inner surface of the second main portion 35a and the inner surface of the second bent portion 36a (θ1<θ2).

[0133] In the first side lip 23a, the angle θ1 between the inner circumferential surface of the first main portion 31a and the inner circumferential surface of the first bent portion 32a is set to be smaller than the angle θ2 between the inner circumferential surface of the second main portion 35a and the inner circumferential surface of the second bent portion 36a of the second side lip 24a. Therefore, in an elastically deformed state, the intersection angle between the inner circumferential surface of the first bent portion 32a and the flat portion 12 is large. This reduces adhesion of the first bent portion 32a to the flat portion 12, thereby keeping the sealing torque of the first side lip 23a low. Furthermore, the contact pressure is likely to peak on the side of the sliding contact portion between the first bent portion 32a and the flat portion 12 where muddy water enters. Specifically, the first ridge portion 34a of the first bent portion 32a and a portion of the inner peripheral surface near the first ridge portion 34a are in sliding contact with the flat portion 12, which makes it easier for a peak in contact pressure to occur at the contact portion between the first ridge portion 34a and the flat portion 12. Therefore, the first side lip 23a can adequately perform its role of preventing the intrusion of muddy water. Furthermore, the reduced contact width between the first bent portion 32a and the flat portion 12 also reduces the sealing torque of the first side lip 23a.

[0134] The second side lip 24a has a second bent portion 36a, which is its tip, in sliding contact with the inclined portion 13, which is formed by an inclined surface, and therefore the angle change from the free state to the elastically deformed state (sliding contact state) is large. Furthermore, the angle θ2 between the inner peripheral surface of the second main portion 35a and the inner peripheral surface of the second bent portion 36a of the second side lip 24a is set to be larger than the angle θ1 between the inner peripheral surface of the first main portion 31a of the first side lip 23a and the inner peripheral surface of the first bent portion 32a. Therefore, the contact width with the inclined portion 13 is smaller than when the second bent portion 36a is not provided at the tip, but is larger than the contact width between the first bent portion 32a and the flat portion 12. Specifically, the second bent portion 36a is in sliding contact with the inclined portion 13 over a relatively wide area of ​​the second ridge portion 38a and the inner peripheral surface of the second bent portion 36a. As a result, the distribution of the contact pressure between the second bent portion 36a and the inclined portion 13 becomes gentle. Therefore, the second side lip 24a can adequately prevent the movement of grease. Furthermore, the contact width of the second side lip 24a with the inclined portion 13 is smaller than in a case where the second bent portion 36a is not provided, thereby reducing the sealing torque of the second side lip 24a. Furthermore, since the sliding contact state of the second side lip 24a is closer to that of the first side lip 23a, adhesion between the first side lip 23a and the second side lip 24a, which is caused by fluctuations in the internal pressure in the space between the first side lip 23a and the second side lip 24a, is reduced. This also reduces the sealing torque of the first side lip 23a and the second side lip 24a.

[0135] Furthermore, in the illustrated example, the first bent point 33a is located beyond the inclined portion 13 (or the flat portion 12) in the axial direction, and the second bent point 37a is located beyond the inclined portion 13 in the axial direction. The first axial distance A from the first bent point 33a to the intersection X1 between the inclined portion 13 (or the flat portion 12) and the inner circumferential surface of the first main portion 31a is shorter than the second axial distance B from the second bent point 37a to the intersection X2 between the inclined portion 13 and the inner circumferential surface of the second main portion 35a. This also contributes to reducing the sealing torque of the first side lip 23a and the second side lip 24a. Furthermore, the contact pressure between the first bent portion 32a and the flat portion 12 tends to peak on the side where muddy water penetrates. Furthermore, the contact width of the second bent portion 36a with the inclined portion 13 becomes larger to some extent, resulting in a smoother distribution of the contact pressure.

[0136] The other configurations and effects of the third example are the same as those of the first example.

[0137] [Example 4] A fourth example of the embodiment of the present disclosure will be described with reference to FIG.

[0138] This example is a modification of Example 3, in which a portion of the structure of the seal ring 5c ​​is changed from the structure of the seal ring 5b of Example 3. The structures of the first side lip 23a, the second side lip 24a, and the grease lip 39 provided on the seal ring 5c ​​are the same as the structures of the first side lip 23a, the second side lip 24a, and the grease lip 39 provided on the seal ring 5b of Example 3, and therefore redundant explanations will be omitted.

[0139] The seal ring 5c ​​of this example does not have the dam portion 40 and the eaves lip 41 (see FIG. 6) that are provided in the seal ring 5b of the third example. Therefore, the structures of the core metal 25b and the seal base 30b that constitute the seal ring 5c ​​are different from the structures of the core metal 25 and the seal base 30 that constitute the seal ring 5b of the third example.

[0140] Specifically, the core metal 25b has a substantially L-shaped cross section, and includes a cylindrical fitting tube portion 27 and an inward flange portion 29b that is bent radially inward from the axially outer end of the fitting tube portion 27.

[0141] The seal base 30b covers the axially outer surface of the inward flange 29b, the radially inner portion of the axially inner surface, and the inner circumferential surface. The outer circumferential surface of the seal base 30b contacts the inner circumferential surface of the outer ring 2 with an interference fit when the fitting tubular portion 27 of the core 25b is tightly fitted into the axially outer end of the outer ring 2.

[0142] In this example as well, not only can the torque be reduced, but the two side lips 23a, 24a of the seal ring 5c ​​can also fully fulfill their respective roles.

[0143] Other configurations and effects of the fourth example are the same as those of the first and third examples.

[0144] The first to fourth embodiments can be combined as appropriate as long as no contradiction occurs. [Explanation of symbols]

[0145] 1, 1a Hub unit bearing 2 outer ring 3. Hub 4a, 4b rolling elements 5, 5a, 5b, 5c Seal rings 6a, 6b Outer ring raceway 7 Stationary Flange 8a, 8b Inner raceway 9 Rotating flange 10 Pilot Division 11, 11a Seal sliding surface 12, 12a flat part 13, 13a Slope section 14, 14a Cylindrical surface part 15 Hub wheel 16 Inner Circle 17 Small diameter stepped section 18 Step surface 19 Crimping part 20a, 20b retainer 21 Annular Space 22 Bearing cap 23 First side lip 24 Second side lip 25, 25a, 25b core metal 26, 26a Sealing material 27, 27a Fitting cylinder part 28 Outward flange 29, 29a, 29b Inward flange 30, 30a, 30b Seal base 31, 31a First main part 32, 32a 1st bending part 33, 33a 1st bending point 34, 34a First ridge 35, 35a Second main part 36, 36a 2nd bending part 37, 37a 2nd bending point 38, 38a Second ridge 39 Grease Lip 40 Weir 41 Eaves lip 42 Slinger 43 Combination Seal Ring 100 Hub unit bearing 101 outer ring 102 Hub 103 Annular Space 104 Seal ring 105 First side lip 106 Second side lip 107 Grease Lip 108 Seal sliding surface 109 Plane section 110 Inclined section 111 Cylindrical surface part

Claims

1. 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; 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 supported by the outer ring and closing an opening of an annular space between an inner peripheral surface of the outer ring and an outer peripheral surface of the hub, The seal ring has a first side lip extending in an axial direction and a second side lip located radially inward of the first side lip and extending in the axial direction, the first side lip has a first main portion, a first bent portion located on a tip side of the first main portion and bent radially inward relative to the first main portion, and a first bent point connecting an inner circumferential surface of the first main portion and an inner circumferential surface of the first bent portion, the second side lip has a second main portion, a second bent portion located on a tip side of the second main portion and bent radially inward relative to the second main portion, and a second bent point connecting an inner circumferential surface of the second main portion and an inner circumferential surface of the second bent portion, The hub or a member fixed to the hub has a flat portion that is formed of an annular flat surface perpendicular to the central axis of the hub and with which the first bent portion slides, and an inclined portion that is formed of an inclined surface that is curved or linearly inclined in a direction radially outward as it approaches the flat surface in the axial direction, and with which the second bent portion slides, When the first side lip and the second side lip are shown in a free state in a cross section cut by an imaginary plane including the center axis of the hub, the first bending point is located at a position beyond the flat portion or the inclined portion in the axial direction, and the second bending point is located at a position beyond the inclined portion in the axial direction, a first axial distance from the first bending point to an intersection point between the flat portion or the inclined portion and the inner circumferential surface of the first main portion is shorter than a second axial distance from the second bending point to an intersection point between the inclined portion and the inner circumferential surface of the second main portion; Hub unit bearing.

2. 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; 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 supported by the outer ring and closing an opening of an annular space between an inner peripheral surface of the outer ring and an outer peripheral surface of the hub, The seal ring has a first side lip extending in an axial direction and a second side lip located radially inward of the first side lip and extending in the axial direction, the first side lip has a first main portion, a first bent portion located on a tip side of the first main portion and bent radially inward relative to the first main portion, and a first bent point connecting an inner circumferential surface of the first main portion and an inner circumferential surface of the first bent portion, the second side lip has a second main portion, a second bent portion located on a tip side of the second main portion and bent radially inward relative to the second main portion, and a second bent point connecting an inner circumferential surface of the second main portion and an inner circumferential surface of the second bent portion, The hub or a member fixed to the hub has a flat portion that is formed of an annular flat surface perpendicular to the central axis of the hub and with which the first bent portion slides, and an inclined portion that is formed of an inclined surface that is curved or linearly inclined in a direction radially outward as it approaches the flat surface in the axial direction, and with which the second bent portion slides, When the first side lip and the second side lip are shown in a free state in a cross section cut by an imaginary plane including the center axis of the hub, an angle formed between an inner peripheral surface of the first main portion and an inner peripheral surface of the first bent portion is smaller than an angle formed between an inner peripheral surface of the second main portion and an inner peripheral surface of the second bent portion; Hub unit bearing.

3. 3. The method according to claim 1, wherein the flat portion and the inclined portion are provided directly on the hub. The hub unit bearing according to claim 1.

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