Hub unit bearing and hub unit bearing with brake rotor

Abstract

To provide a hub unit bearing which can achieve improvement of workability of assembly work while securing sealability achieved by a seal ring.SOLUTION: A rotary flange 11 included in a hub 3 has a substantially circular-ring plate shape in whole and has a plurality of thin parts 19 and a plurality of thick parts 20, protruding to the axial inner side farther than the thin parts 19, alternately in a circumferential direction. A stud 6 inserted into an attachment hole 21 included in each thick part 20 includes a head part 23 having an outer peripheral surface having a circular profile shape and butted with an axial inner surface of the thick part 20. A weir part 42 forming a seal ring 5 has an outer diameter which is the same as an inscribed circle diameter of the head parts 23 or slightly smaller than the inscribed circle diameter, is disposed at the axial inner side slightly relative to an axial inner end surface 23a of the head part 23, and has a planar facing surface 44 facing an axial inner surface of the rotary flange 11.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a hub unit bearing and a hub unit bearing with a braking rotor. [Background technology]

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

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

[0004] The hub unit bearing further includes a seal ring that closes the axially outer opening of the rolling element installation space that exists between the inner surface of the outer ring and the outer surface of the hub, in order to prevent the intrusion of muddy water and the like from the outside.

[0005] FIG. 9 shows a seal ring 102 that closes the axially outer opening of a rolling element installation space 101, which is incorporated into a hub unit bearing 100 of a conventional structure described in JP 2017-198316 A (Patent Document 1).

[0006] The seal ring 102 closes an opening on the axially outer side (the right side in FIG. 9) of a rolling element installation space 101 that exists between the inner peripheral surface of the outer ring 103 and the outer peripheral surface of the hub 104 .

[0007] The seal ring 102 has a metal, annular core bar 105 fixed to the axially outer end of the outer ring 103 , and a seal member 106 made of an elastic material and bonded to the core bar 105 .

[0008] The core metal 105 is configured in an overall circular ring shape, and is supported and fixed to the axially outer end of the outer ring 103 by press-fitting.

[0009] The core metal 105 includes a seal fitting cylindrical portion 107 , an outward flange portion 108 , a reinforcing cylindrical portion 109 , and a support plate portion 110 .

[0010] The seal fitting tubular portion 107 is tightly fitted and fixed to the axially outer end of the outer ring 103. The outward flange portion 108 bends radially outward from the axially outer end of the seal fitting tubular portion 107 and extends radially outward along the axially outer end face of the outer ring 103. The reinforcing tubular portion 109 has a cylindrical shape and extends axially inward from the radially outer end of the outward flange portion 108. The support plate portion 110 has a generally crank-shaped cross section and its radially outer end is connected to the axially inner end of the seal fitting tubular portion 107.

[0011] The seal material 106 is configured in an overall circular ring shape, and is bonded to the surface of the core metal 105 by vulcanization molding.

[0012] The seal material 106 includes three seal lips 111 a to 111 c, a dam portion 112 , and an overhanging lip 113 .

[0013] The three seal lips 111a to 111c are provided on the radially inner side of the seal material 106 reinforced by the support plate portion 110. The three seal lips 111a to 111c have their respective tips in sliding contact with the axially inner side surface of a rotating flange 114 provided on the hub 104 or the outer circumferential surface of the axially intermediate portion of the hub 104 over the entire circumference.

[0014] Weir portion 112 is provided at a radially outer end portion of sealing material 106, and protrudes radially outward beyond the axially outer end portion of outer ring 103. Weir portion 112 has an annular dam portion main body 115 that is located axially outward beyond the axially outer end face of outer ring 103, and a cylindrical cover portion 116 that extends from dam portion main body 115 toward the axially inner side (to the left side in FIG. 9 ).

[0015] The dam portion main body 115 is reinforced by the radially outer end of the outward flange portion 108. The cover portion 116 is reinforced by the reinforcing tube portion 109. The cover portion 116 covers the axially outer end of the outer peripheral surface of the outer ring 103. The inner peripheral surface of the cover portion 116 is provided with a ring-shaped lip portion 117 that protrudes radially inward. The tip portion of the lip portion 117 is in contact with the outer peripheral surface of the outer ring 103 with a tightening margin.

[0016] The eaves lip 113 has a cylindrical shape. An axially inner end face of the eaves lip 113 is connected to an axially outer end face of the weir portion main body 115. An axially outer end face of the eaves lip 113 closely faces an axially inner surface of the rotating flange 114 over the entire circumference.

[0017] While the vehicle is traveling, a rotating air current is generated around the outer ring 103 due to the rotation of the wheel and the braking rotor. Muddy water splashed up from the road surface is caught in the rotating air current and circulates in the form of water droplets around the outer ring 103. When the vehicle stops and the rotating air current subsides, the water droplets that have been circulating around the outer ring 103 together with the rotating air current fall onto the outer peripheral surface of the outer ring 103 and the axially inner surface of the rotating flange 114 at the top of the hub unit bearing 100.

[0018] The dam portion 112 blocks water droplets that fall onto the outer peripheral surface of the outer ring 103 and flow axially outward along the outer peripheral surface, thereby preventing the water droplets from entering between the axially outer end face of the outer ring 103 and the axially inner surface of the rotating flange 114.

[0019] The eaves lip 113 prevents foreign matter such as muddy water splashed up from the road surface from directly entering between the axially outer end face of the outer ring 103 and the axially inner side face of the rotating flange 114. This protects the seal lips 111a to 111c and improves the durability of the seal lips 111a to 111c. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] JP 2017-198316 A Summary of the Invention [Problem to be solved by the invention]

[0021] To assemble the seal ring 102 of the conventional structure by press-fitting it onto the axially outer end of the outer ring 103, a method is adopted in which the flat pressed surface 118 provided on the axially outer surface of the portion of the seal material 106 that covers the outward flange portion 108 is pressed in the axial direction with a pressing jig.

[0022] However, because the seal ring 102 of the conventional structure is provided with the eaves lip 113 extending axially from the axially outer end face of the dam portion 112, the radial width of the pressed surface 118 is reduced by the amount of the eaves lip 113, and it may become impossible to position the pressed surface 118 in an appropriate radial position. This may reduce the ease of assembly of the seal ring 102, and may reduce the ease of assembly of the hub unit bearing.

[0023] In particular, since the seal ring 102 of the conventional structure has the lip portion 117 on the inner peripheral surface of the dam portion 112, when the seal ring 102 is pressed in by a pressing jig, it is necessary to take into consideration the curling of the lip portion 117, making the assembly work difficult. Therefore, the presence of the eaves lip 113 may further reduce the workability of the assembly work of the seal ring 102.

[0024] In the hub unit bearing assembly factory, the seal rings are wound in a roll and stacked in the axial direction before being set in a positioning device. The seal rings are then separated and picked out one by one using an extracting tool and attached to the axially outer end of the outer ring.

[0025] However, when the seal rings 102 of the conventional structure are stacked in the axial direction, the axial end face of the cover portion 116 and the axial end face of the eaves lip 113 abut against each other between two adjacent seal rings 102 (see FIG. 3 of Patent Document 1), making it difficult to insert an excision jig from the radial outside between two adjacent seal rings 102. This makes it difficult to separate and remove the seal rings 102 one by one from the positioning device, which may reduce the ease of assembly of the hub unit bearing.

[0026] The present invention has been made to solve the above-mentioned problems, and has an object to provide a hub unit bearing and a hub unit bearing with a braking rotor that can improve the workability of assembly work while ensuring the sealing performance provided by a seal ring. [Means for solving the problem]

[0027] A hub unit bearing according to one aspect of the present invention includes an outer ring, a hub, a plurality of rolling elements, a seal ring, and a plurality of connecting members. 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, and has a rotating flange that protrudes radially outward at a portion located axially outward from the outer ring. The plurality of rolling elements are disposed so as to roll freely between the double row outer ring raceways and the double row inner ring raceways. The seal ring has a dam portion that protrudes radially outward beyond the axially outer end of the outer ring, and closes the axially outer opening of the rolling element installation space that exists between the inner surface of the outer ring and the outer peripheral surface of the hub. The multiple connecting members are used to fix the wheel and the braking rotor to the rotating flange. The rotating flange has a generally circular disk shape overall, and has a plurality of thin portions and a plurality of thick portions that protrude axially inward beyond the thin portions, alternately arranged in the circumferential direction. Each of the thick portions has a mounting hole through which the connecting member is inserted. Each of the plurality of connecting members has an outer circumferential surface having a circular contour and a head that abuts against an axially inner surface of the thick-walled portion. The dam portion has an outer diameter that is the same as or slightly smaller than the inscribed circle diameter passing through the radially inner ends of each of the multiple heads, is positioned slightly axially inward from the axially inner end faces of the heads, and has a planar opposing surface that faces the axially inner surface of the rotating flange.

[0028] A hub unit bearing with a braking rotor according to one aspect of the present invention comprises an outer ring, a hub, a plurality of rolling elements, a seal ring, a plurality of connecting members, and a braking rotor. 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, and has a rotating flange that protrudes radially outward at a portion located axially outward from the outer ring. The plurality of rolling elements are disposed so as to roll freely between the double row outer ring raceways and the double row inner ring raceways. The seal ring has a dam portion that protrudes radially outward beyond the axially outer end of the outer peripheral surface of the outer ring, and closes the axially outer opening of the rolling element installation space that exists between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub. The multiple connecting members are used to fix the wheel and the braking rotor to the rotating flange. The braking rotor has a planar mating surface on its axially inner side, and is fixed to the rotating flange by the multiple connecting members with the mating surface overlapping the axially outer side of the rotating flange. The rotating flange has a plurality of flange pieces each extending in a radial direction and each having a mounting hole formed therein through which the connecting member is inserted. Each of the plurality of connecting members has an outer circumferential surface with a circular contour and has a head that abuts against the axially inner surface of the flange piece. The dam portion has an outer diameter that is the same as or slightly smaller than the inscribed circle diameter passing through the radially inner ends of each of the multiple heads, is positioned slightly axially inward from the axially inner end faces of the heads, and has planar opposing surfaces that face each of the axially inner surface of the rotating flange and the overlapping surface. Effect of the Invention

[0029] According to the hub unit bearing and the hub unit with braking rotor according to one aspect of the present invention, the efficiency of the assembly work can be improved while ensuring the sealing performance provided by the seal ring. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a cross-sectional view showing a hub unit bearing according to a first example of the embodiment. [Diagram 2] FIG. 2 is a partially enlarged view of FIG. [Diagram 3] FIG. 3 is an end view seen from the right side of FIG. [Figure 4] FIG. 4 is a schematic diagram corresponding to a cross section taken along line AA in FIG. 1, showing a hub unit bearing according to a first example of an embodiment with the outer ring and rolling elements omitted. [Diagram 5] 5(A) and 5(B) are partially enlarged views of FIG. 4 shown to explain the principle of generation of Karman vortices and the rotating airflow generated with the rotation of the rotating flange. [Figure 6] FIG. 6 is a cross-sectional view showing a state in which seal rings to be incorporated into a hub unit bearing according to a first example of the embodiment are stacked in the axial direction. [Figure 7] FIG. 7 is a diagram showing a second example of the embodiment, and corresponds to FIG. [Figure 8] FIG. 8 is a diagram showing a second example of the embodiment, and corresponds to FIG. [Figure 9] FIG. 9 is a cross-sectional view showing a seal ring incorporated into a hub unit bearing of a conventional structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] [First Example of Implementation] A first example of the embodiment will be described with reference to FIGS. 1 to 6. FIG.

[0032] The hub unit bearing of the present invention can be applied to hub unit bearings of various structures, but in this example, a case where it is applied to a hub unit bearing for a driven wheel will be described.

[0033] The hub unit bearing 1 of this example includes an outer ring 2, a hub 3, a plurality of rolling elements 4a, 4b, a seal ring 5, and a plurality of studs 6. In this example, the studs 6 correspond to the connecting member described in the claims.

[0034] In the following description of the hub unit bearing 1, the left side in Figures 1 and 2, which is located on the outer side in the width direction of the vehicle when assembled to the vehicle, is referred to as the outer axial side, and the right side in Figures 1 and 2, which is located on the central side in the width direction of the vehicle when assembled to the vehicle, is referred to as the inner axial side.

[0035] The outer ring 2 is made of a hard metal such as medium carbon steel. The outer ring 2 has double-row outer ring raceways 7a, 7b on its inner circumferential surface. Furthermore, the outer ring 2 has a stationary flange 8 that protrudes radially outward at an axially intermediate portion. The stationary flange 8 has support holes 9 that penetrate in the axial direction at multiple circumferential positions at the radially intermediate portion.

[0036] In this example, the support hole 9 is configured as a screw hole. The outer ring 2 is supported and fixed to the suspension by threading a support bolt, which is inserted through a through hole provided in the knuckle of the suspension, into the support hole 9 of the stationary flange 8 from the inside in the axial direction, so that the outer ring 2 does not rotate even when the wheel rotates.

[0037] The hub 3 is disposed radially inside the outer ring 2 and coaxially with the outer ring 2. The hub 3 has double row inner ring raceways 10a, 10b on its outer peripheral surface. Furthermore, the hub 3 has a rotation flange 11 that protrudes radially outward at a portion located axially outward from the outer ring 2. The hub 3 also has a cylindrical pilot portion 12 at its axially outer end.

[0038] The hub 3 has a groove shoulder 13 on its outer peripheral surface in a portion that is located between the axially outer inner ring raceway 10a and the rotating flange 11. The groove shoulder 13 is connected to the radially inner end of the axially inner surface of the rotating flange 11 and is also connected to the axially outer inner ring raceway 10a. The groove shoulder 13 is configured in the shape of a cylindrical surface.

[0039] The rotating flange 11 of this embodiment is a so-called scallop flange, which has a generally circular disk shape as a whole and has a plurality of thin portions 19 and a plurality of thick portions 20 arranged alternately in the circumferential direction.

[0040] The rotating flange 11 has a root portion 14 and a thickness-changing portion 15 .

[0041] The base portion 14 is provided on the radially inner side of the rotating flange 11, and its axial thickness does not change in the circumferential direction. The thickness varying portion 15 is provided on the radially outer side of the rotating flange 11, and its axial thickness changes in the circumferential direction.

[0042] The axially inner surface of root portion 14 and the axially inner surface of thickness changing portion 15 are connected by a radially outwardly facing step portion 16 provided on root portion 14. In this example, the axially outer surface of rotating flange 11 including thickness changing portion 15 is configured by a circular ring-shaped flat surface perpendicular to the central axis of hub 3.

[0043] The root portion 14 has, on its axially inner surface, a curved portion 17, a flat portion 18, and a step portion 16, in that order from the radially inner side.

[0044] The curved surface portion 17 is provided at the radially inner end of the axially inner surface of the base portion 14 and has a concave arc-shaped cross section. The curved surface portion 17 is connected to the groove shoulder portion 13 provided on the outer peripheral surface of the hub 3. The flat surface portion 18 is provided at the radially middle portion of the axially inner surface of the base portion 14 and is constituted by a circular flat surface perpendicular to the central axis of the hub 3. The step portion 16 is provided at the radially outer end of the axially inner surface of the base portion 14. The step portion 16 is constituted by a substantially conical cylindrical surface facing radially outward, which extends from the radially outer end of the flat surface portion 18 toward the axially outer side. In the illustrated example, the outer diameter of the boundary portion between the step portion 16 and the flat surface portion 18 is approximately the same as the outer diameter of the axially outer end of the outer ring 2.

[0045] The thickness changing portion 15 has a plurality of thin portions 19 and a plurality of thick portions 20 alternately arranged in the circumferential direction. The number of thin portions 19 and thick portions 20 is arbitrary, but in this example, the thickness changing portion 15 has five thin portions 19 and five thick portions 20. The thin portions 19 and thick portions 20 are arranged alternately and at equal pitches in the circumferential direction. Therefore, the thin portions 19 and thick portions 20 are arranged with a phase shift of 72 degrees in the circumferential direction.

[0046] Each of the thick-walled portions 20 extends radially from the root portion 14. Each of the thick-walled portions 20 has an axial thickness greater than that of the thin-walled portions 19, and protrudes axially inward more than the thin-walled portions 19. The axially inner surface of each of the thick-walled portions 20 is formed by a plane perpendicular to the central axis of the hub 3. Each of the thick-walled portions 20 has a generally trapezoidal shape, as viewed from the axially inner side, with the circumferential width gradually decreasing radially outward.

[0047] Each of the thick-walled portions 20 has a mounting hole 21 through which the stud 6 is inserted. The mounting hole 21 is a through-hole that passes axially through a radially intermediate portion of each of the thick-walled portions 20. In this example, the mounting hole 21 is configured as a cylindrical hole.

[0048] The thin-walled portions 19 connect the circumferentially adjacent thick-walled portions 20. When viewed from the axially inner side, each of the thin-walled portions 19 has a generally sector shape whose circumferential width gradually increases radially outward.

[0049] The ratio of the axial thickness of the thin-walled portion 19 to the axial thickness of the thick-walled portion 20 is not particularly limited, but can be greater than or equal to 1 / 3 and less than or equal to 2 / 3, preferably greater than or equal to 1 / 2 and less than or equal to 3 / 5, in the portion whose radial position coincides with the radially outer end of the dam portion 42 described later.

[0050] The axially inner surface of the thin-walled portion 19 is configured with an inclined surface that is inclined in the axially outward direction as it approaches the radially outer side. In this example, the axially inner surface of the thin-walled portion 19 has a cross-sectional shape that is concave at the radially inner end, and the other portions, i.e., a radially intermediate portion and a radially outer end, have a linear cross-sectional shape.

[0051] The thick-walled portion 20 has a mounting hole 21 into which the stud 6 is press-fitted with serrations.

[0052] The multiple studs 6 are used to connect the wheels that make up the wheel and rotating braking bodies such as discs and drums to the rotating flange 11. The studs 6 are supported and fixed to the rotating flange 11 by being press-fitted one by one into each of the mounting holes 21.

[0053] Each of the studs 6 has a shank 22 and a head 23 .

[0054] The shaft portion 22 has a male thread portion 24 at the axially outer end portion to the middle portion of the outer peripheral surface, and has a serration portion 25 at the axially inner end portion of the outer peripheral surface.

[0055] The head 23 is provided integrally with the shaft portion 22 and is provided axially inside the shaft portion 22. The head 23 has an outer diameter dimension larger than that of the shaft portion 22. In this example, the head 23 has a head body 26 and a chamfered portion 27.

[0056] Head body 26 has a columnar shape and has a cylindrical outer peripheral surface. Therefore, the contour shape of the outer peripheral surface of head body 26 is circular. Chamfered portion 27 has a truncated cone shape and has a conical cylindrical outer peripheral surface. Therefore, the contour shape of the outer peripheral surface of chamfered portion 27 is also circular. Note that, as long as the contour shape of the outer peripheral surface of the head is circular, the head can be entirely cylindrical or entirely truncated cone. The axial dimension of head 23 is not particularly limited, but is, for example, 3 mm or more and 7 mm or less.

[0057] Each of the studs 6 is supported and fixed to the rotatable flange 11 by inserting the shaft portion 22 into the mounting hole 21 from the axially inner side and press-fitting the serration portion 25 into the mounting hole 21 from the axially inner side. In this state, the male thread portion 24 protrudes axially outward beyond the axially outer surface of the rotatable flange 11. In addition, the axially outer end face of the head 23 abuts against the axially inner surface of the thick-walled portion 20 that constitutes the rotatable flange 11. This regulates the axial position of the stud 6 relative to the rotatable flange 11.

[0058] A braking rotating body such as a brake disc and a wheel of a vehicle are connected and fixed to the rotating flange 11 by inserting a pilot portion 12 into a central hole provided in the center of each of them and inserting a stud 6 into through holes provided at multiple locations in the circumferential direction of each of them in the radial middle portion, and then screwing a hub nut (not shown) onto the tip of the stud 6.

[0059] In this example, the hub 3 is formed by combining an inner ring 28 and a hub ring 29 .

[0060] The inner ring 28 is made of a hard metal such as bearing steel, etc. The inner ring 28 has an inner ring raceway 10b on the axially inner side on its outer circumferential surface.

[0061] The hub ring 29 is made of a hard metal such as medium carbon steel, and includes an inner ring raceway 10a on the axially outer side, a rotating flange 11, and a pilot portion 12.

[0062] The hub ring 29 has a small diameter step 30, located axially inward of the axially outer inner ring raceway 10a, which has an outer diameter smaller than that of an adjacent axially outward portion and onto which the inner ring 28 is fitted. Furthermore, the hub ring 29 has a step surface 31 facing axially inward at the axially outer end of the small diameter step 30, and a crimped portion 32 bent radially outward from the axially inner end of the small diameter step 30.

[0063] The hub 3 is constructed by fitting the inner ring 28 onto the small diameter step 30 of the hub ring 29 and clamping the inner ring 28 from both axial sides between the step surface 31 and the crimping portion 32 of the hub ring 29, thereby joining and fixing the inner ring 28 to the hub ring 29. The hub ring and the inner ring can also be joined by screwing a nut onto the axially inner end of the hub ring that protrudes from the axially inner end of the inner ring.

[0064] Since the hub unit bearing 1 of this example is a hub unit bearing for a driven wheel, the hub 3 is solid. However, the hub unit bearing of one aspect of the present invention can also be applied to a hub unit bearing for a driving wheel. In this case, the hub has a spline hole penetrating in the axial direction at the center. The tip of a drive shaft that is rotated and driven by an engine or an electric motor as a drive source is spline-engaged with the spline hole. When the automobile is traveling, the hub is rotated by the drive shaft, thereby rotating and driving the wheel and braking rotor that are joined and fixed to the rotating flange of the hub.

[0065] 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 7a, 7b and the double row inner ring raceways 10a, 10b in a rollable manner while being held by cages 33a, 33b. As a result, the hub 3 is supported on the radial inside of the outer ring 2 in a rotatable manner.

[0066] The hub unit bearing 1 of this example has an equal diameter PCD type structure in which the pitch circle diameter of the rolling elements 4a in the axially outer row is equal to the pitch circle diameter of the rolling elements 4b in the axially inner row. However, the hub unit bearing of one aspect of the present invention can also be applied to a different diameter PCD type hub unit bearing in which the pitch circle diameter of the rolling elements in the axially outer row is larger or smaller than the pitch circle diameter of the rolling elements in the axially inner row. Also, although balls are used as the rolling elements 4a and 4b in the hub unit bearing 1 of this example, tapered rollers can be used instead of balls.

[0067] The seal ring 5 is attached to the axially outer end of the outer ring 2 and closes the axially outer opening of the rolling element installation space 34 that exists between the inner surface of the outer ring 2 and the outer surface of the hub 3.

[0068] The seal ring 5 has a metal, annular core 35 fixed to the axially outer end of the outer ring 2, and a seal member 36 made of an elastic material and bonded to the core 35.

[0069] The core metal 35 is formed into an annular shape by pressing a metal plate such as a mild steel plate. The core metal 35 includes a seal fitting tubular portion 37 that is tightly fitted into the axially outer end of the outer ring 2, an outward flange portion 38 that is bent radially outward from the axially outer end of the seal fitting tubular portion 37 and extends radially outward along the axially outer end face of the outer ring 2, and a support plate portion 39 that is folded back radially inward from the axially inner end of the seal fitting tubular portion 37 in a substantially U-shape and has an axially outer end that extends radially inward. The axial position of the core metal 35 relative to the outer ring 2 is regulated by abutting the axially inner side surface of the outward flange portion 38 against the axially outer end face of the outer ring 2 via a part of the seal material 36 (a gasket portion 43 described later).

[0070] In this example, the radially outer end of the outward flange 38 protrudes slightly radially outward from the axially outer end of the outer ring 2, and is a free end. In the illustrated example, the radially outer end of the outward flange 38 protrudes radially outward from the axially outer end of the outer ring 2 by an amount approximately equal to the plate thickness of the core metal 35. This ensures a wide radial width of the pressed surface 48 described below, making it easier to assemble the seal ring 5 by press-fitting it into the axially outer end of the outer ring 2. However, the radially outer end of the outward flange can also be positioned radially inward from the axially outer end of the outer ring, as long as it does not interfere with ensuring the pressed surface 48.

[0071] The seal material 36 is made of an elastic material such as an elastomer like rubber (for example, vulcanization molding), and is bonded and fixed to the core metal 35. The seal material 36 includes a seal base 40, seal lips 41a, 41b, 41c, and a dam portion 42. The seal ring 5 of this example does not include an overhanging lip. Note that Figs. 1 and 2 show the shapes of each part of the seal material 36 in a free state.

[0072] The seal base 40 is joined and fixed to the core metal 35 so as to cover, among the surfaces of the core metal 35, the radially outer portion of the axially inner surface of the outward flange portion 38 and the axially outer side surface, the inner peripheral surface of the seal fitting cylindrical portion 37, and the axially outer side surface, inner peripheral surface, and radially inner portion of the axially inner surface of the support plate portion 39. A gasket portion 43 is provided on a portion of the seal base 40 covering the radially outer portion of the axially inner surface of the outward flange portion 38. The gasket portion 43 elastically abuts on the axially outer end face of the outer ring 2, thereby preventing foreign matter such as muddy water from entering the rolling element installation space 34 from the external space through the portion between the outer ring 2 and the core metal 35, and preventing grease sealed in the rolling element installation space 34 from leaking into the external space.

[0073] The tip end of each of the seal lips 41a, 41b, 41c is in sliding contact with the axially inner surface of the rotating flange 11 or the axially middle portion of the outer circumferential surface of the hub 3. In this example, the seal material 36 has three seal lips 41a, 41b, 41c. However, the number of seal lips may be less or more than three.

[0074] Of the three seal lips 41a, 41b, 41c, the radially outermost seal lip 41a extends axially and radially outward from a portion of the seal base 40 that covers the axially outer surface of the radially inner portion of the support plate portion 39, and has its tip in sliding contact with the flat portion 18 of the root portion 14 that constitutes the rotating flange 11. The second radially outward seal lip 41b extends axially outward from a portion of the seal base 40 that covers the axially outer surface of the radially inner portion of the support plate portion 39, and has its tip in sliding contact with the curved portion 17 of the root portion 14 that constitutes the rotating flange 11. The radially innermost seal lip 41c extends axially and radially inward from a portion of the seal base 40 that covers the inner peripheral surface of the support plate portion 39, and has its tip in sliding contact with the outer peripheral surface of the groove shoulder portion 13.

[0075] The dam portion 42 protrudes radially outward from a portion of the seal base 40 that covers the radially outer portion of the outward flange portion 38, and is provided at the radially outer end of the seal ring 5. The dam portion 42 protrudes radially outward beyond the axially outer end of the outer ring 2. The dam portion 42 blocks muddy water that has flowed axially outward along the outer peripheral surface of the outer ring 2, thereby preventing the muddy water from entering between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 11.

[0076] The dam portion 42 covers the radially outer end portion of the outward flange portion 38. In this example, only the radially inner end portion of the dam portion 42 covers the radially outer end portion of the outward flange portion 38. Therefore, only the radially inner end portion of the dam portion 42 is reinforced by the radially outer end portion of the outward flange portion 38.

[0077] The dam portion 42 has an axial dimension that is substantially constant over the entire radial length, and is configured in a circular plate shape. 42 is the plate thickness t of the core bar 35 (the radially outer portion of the outward flange portion 38 covered by the dam portion 42). 35 It is about twice as large as (T 42 ≒2t 35 ).

[0078] In this example, the outer diameter dimension D of the dam portion 42 42 is sufficiently larger than the outer diameter of the outer ring 2 at the axially outer end thereof and is an inscribed circle diameter d 23 or the inscribed circle diameter d 23 (D 42 ≦d 23 Specifically, the inscribed circle diameter d 23 and outer diameter D 42 Difference from (d 23 -D 42 ) is set to 0 mm or more and 4 mm or less, preferably 1 mm or more and 3 mm or less.

[0079] The dam portion 42 in this example does not have an overhang lip on its axially outer surface, but instead has a planar opposing surface 44 that is positioned slightly axially inward of the axially inner end surfaces 23a of the heads 23 of each of the multiple studs 6 and faces the axially inner surface of the rotating flange 11. The opposing surface 44 is a plane perpendicular to the central axis of the hub 3. The opposing surface 44 also faces the step 16 of the root portion 14, the radially inner portion of the axially inner surface of the thick-walled portion 20, and the radially inner portion of the axially inner surface of the thin-walled portion 19, all of which are part of the axially inner surface of the rotating flange 11.

[0080] In this embodiment, the axial distance between the opposing surface 44 and the axially inner end surface 23a of the head 23 is set to the axial thickness T 42 The axial distance between the opposing surface 44 and the end surface 23a of the head 23 is not particularly limited, but may be, for example, 2 mm or less, and preferably 0.5 mm or more and 1.5 mm or less.

[0081] In this example, the outer diameter dimension D of the dam portion 42 42 The inscribed circle diameter d of head 23 23 or the inscribed circle diameter d 23 and an opposing surface 44 provided on the axially outer surface of the dam portion 42 is positioned slightly axially inward relative to the axially inner end surface 23a of the head portion 23. This brings the outer peripheral edge of the dam portion 42 close to each of the multiple heads 23, and forms an annular partition space 45 between the opposing surface 44 and the axially inner surface of the rotating flange 11, with both axial sides partitioned.

[0082] In this example, by installing the seal ring 5 as described above, it is possible to prevent foreign matter such as muddy water from entering the rolling element installation space 34 from the external space through the gap between the axially outer end face of the outer ring 2 and the axially inner surface of the rotating flange 11, and to prevent grease sealed in the rolling element installation space 34 from leaking into the external space.

[0083] The hub unit bearing 1 of this example further includes a cylindrical bearing cap 46 with a bottom that closes the axially inner opening of the rolling element installation space 34. This prevents foreign matter from the external space from entering the rolling element installation space 34 through the opening and prevents grease sealed in the rolling element installation space 34 from leaking to the external space. Note that instead of the bearing cap 46, the axially inner opening of the rolling element installation space 34 can also be closed with a combination seal ring.

[0084] According to the hub unit bearing 1 of this embodiment, the sealing performance provided by the seal ring 5 can be ensured, while the workability of the assembly work can be improved. In other words, in the hub unit bearing 1 of this example, instead of omitting the eave lip, the outer diameter dimensions and axial position of the dam portion 42 that constitutes the seal ring 5 are devised so that the Karman vortex that is generated on the rear side of the head 23 of the stud 6 in relation to the rotational direction of the rotating flange 11 can be used to expel foreign matter such as muddy water that has adhered to the axial inner surface of the rotating flange 11 to the outside, thereby ensuring the sealing performance of the seal ring 5.

[0085] The reason why the hub unit bearing 1 of this embodiment can ensure the sealing performance of the seal ring 5 will be specifically described below. In this example, the head 23 of the stud 6 has an outer circumferential surface with a circular contour shape, and is disposed so as to protrude axially inward from the axially inner surface of the thick-walled portion 20. For this reason, as shown in Figure 5(A) , when the hub 3 rotates, Karman vortices are generated on the rear side of the head 23 in relation to the rotation direction of the rotating flange 11. Specifically, of the tangents passing through the intersection O between the pitch circle diameter of the stud 6 and the center line of the stud 6, two rows of Karman vortices are generated on the radially outer side and radially inner side, sandwiching a tangent TL that faces rearward in relation to the rotation direction of the rotating flange 11.

[0086] It is known that Karman vortices are likely to occur under conditions where the wind speed is several m / s to several tens of m / s, and the wind speed at which Karman vortices are likely to occur coincides with the moving speed of head 23 on the pitch circle diameter of stud 6 when the vehicle is traveling. For this reason, when rotatable flange 11 rotates, Karman vortices are likely to occur rearward of head 23 in the rotational direction of rotatable flange 11.

[0087] 5(A), the Kármán vortex that occurs radially inward of the tangent TL rotates clockwise as the airflow flows toward the center of the vortex, and the vortex as a whole tries to move radially outward away from the center of the hub 3. However, the Kármán vortex itself hardly moves in the radial or tangential directions, and tends to spread and decay in the axial direction.

[0088] Meanwhile, in this example, the rotating flange 11 is a scallop flange having thin portions 19 and thick portions 20 alternately in the circumferential direction, so that an intermediate space 47 is formed between a pair of circumferentially adjacent thick portions 20, the axially outer side of which is closed by the axially inner side surfaces of the thin portions 19. Then, in the intermediate space 47, a rotating airflow is generated as the rotating flange 11 rotates, as shown by the arrow X in FIG. 5(A). That is, when the rotating flange 11 rotates, of the pair of circumferentially adjacent thick portions 20, the thick portion 20 on the rear side in the rotation direction of the rotating flange 11 pushes the air present in the intermediate space 47 radially outward by the side surface of the thick portion 20 facing the front side in the rotation direction. Also, when the thick portion 20 on the front side in the rotation direction of the rotating flange 11 passes, air is taken into the intermediate space 47 from the radially outer side along the side surface of the thick portion 20 facing the rear side in the rotation direction. As a result, a substantially U-shaped rotating air current is generated in the intermediate space 47, as indicated by the arrow X in FIG. 5(A).

[0089] 5(B), in this example, the Karman vortex generated on the rear side of the head portion 23 in the rotational direction of the rotatable flange 11 rides on the rotating airflow generated by the rotation of the rotatable flange 11, and moves in a roughly U-shape as indicated by arrow X. In other words, it moves radially inward along the circumferential side surface of the thick-walled portion 20 on the front side in the rotational direction of the rotatable flange 11, then moves circumferentially along the step portion 16 of the base portion 14, and then moves radially outward along the thick-walled portion 20 on the rear side in the rotational direction of the rotatable flange 11.

[0090] In particular, in this example, the outer diameter dimension and axial position of the weir portion 42 are devised to bring the outer peripheral edge of the weir portion 42 close to each of the multiple heads 23, and an annular partition space 45 with both axial sides partitioned is formed between the opposing surface 44 of the weir portion 42 and the axial inner surface of the rotating flange 11. This makes it possible to prevent the Karman vortex that has traveled to the partition space 45 on the rotating airflow from spreading in the axial direction and attenuating. This makes it possible to maintain the strength of the Karman vortex, so that foreign matter such as muddy water that has adhered to the axial inner surface of the rotating flange 11 can be collected at the vortex center of the Karman vortex, and can be carried by the rotating airflow together with the Karman vortex and discharged to the radial outside of the rotating flange 11. Therefore, in this example, the sealing performance of the seal ring 5 can be ensured even when the cylindrical eaves lip with its tip portion close to and facing the axial inner surface of the rotating flange 11 is omitted from the seal ring 5.

[0091] In addition, since the seal ring 5 of this embodiment does not have an overhanging lip, the radial width H of the pressed surface 48 that can be pressed by the pressing tool is set to the axially outer surface of the dam portion 42. 48 It is possible to ensure a sufficiently wide area. Also, the pressed surface 48 can be disposed at an appropriate radial position. Therefore, the workability of the installation work of the seal ring 5 can be improved, and the workability of the assembly work of the hub unit bearing 1 can be improved.

[0092] In addition, as shown in Fig. 6, when the seal rings 5 ​​of this example are stacked in the axial direction, a gap can be formed between the dam portions 42 of two adjacent seal rings 5. This allows the cutting tool 49 of the positioning device to be easily inserted between two adjacent seal rings 5 ​​from the outside in the radial direction. This makes it easy to separate and remove the seal rings 5 ​​one by one from the positioning device. As a result, this also improves the workability of the assembly work of the hub unit bearing 1.

[0093] Furthermore, the outer diameter dimension D of the dam portion 42 42 The inscribed circle diameter d of the head 23 23 or the inscribed circle diameter d 23Since the size of the stud 6 is slightly smaller than the above, it is possible to avoid any hindrance to the installation and replacement of the stud 6.

[0094] [Second Example of the Implementation Form] The second embodiment will be described with reference to FIGS.

[0095] The hub unit bearing with braking rotor of this example includes a hub unit bearing 1a and a braking rotor 50. Note that a brake drum may also be used as the braking rotor other than the brake rotor.

[0096] The hub unit bearing 1a includes an outer ring 2, a hub 3a, a plurality of rolling elements 4a, 4b, a seal ring 5, and a plurality of studs 6. In this example, of the hub unit bearing 1a, only the structure of the rotating flange 11a constituting the hub 3a is changed from the structure in the first example of the embodiment.

[0097] The rotating flange 11 a has a root portion 14 and a radial flange portion 51 .

[0098] The radial flange portion 51 is composed of a plurality of flange pieces 52. In this example, the radial flange portion 51 has five flange pieces 52. The plurality of flange pieces 52 are disposed at equal intervals in the circumferential direction.

[0099] Each of the flange pieces 52 extends radially from the root portion 14. The axially inner surface of each of the flange pieces 52 is formed by a plane perpendicular to the central axis of the hub 3a. Each of the flange pieces 52 has a generally trapezoidal shape with a circumferential width that gradually decreases radially outward when viewed from the axially inner side.

[0100] Each of the flange pieces 52 has a mounting hole 21 through which the stud 6 is inserted. The mounting hole 21 is a through hole that passes through a radially intermediate portion of each of the flange pieces 52 in the axial direction.

[0101] The brake rotor 50 is made of a metal material such as cast iron and has a crank-shaped cross section. The brake rotor 50 has a mounting portion 53 on the radially inner side and a disk portion on the radially outer side.

[0102] The mounting portion 53 is a portion that is supported and fixed to the rotating flange 11a, and has a planar mating surface 54 on its axially inner surface that is mated with the axially outer surface of the rotating flange 11a. The mounting portion 53 also has through holes 55 at multiple locations (five locations in the illustrated example) that are equally spaced in the circumferential direction.

[0103] The brake rotor 50 is fixed to the rotating flange 11a by inserting the pilot portion 12 through a central hole 56 provided in the center of each rotor and inserting the shaft portion 22 of the stud 6 through through holes 55 provided at multiple circumferential positions in each radially intermediate portion, and then screwing a hub nut (not shown) onto the tip of the stud 6. With the brake rotor 50 fixed to the rotating flange 11a in this manner, the mating surface 54 of the mounting portion 53 is mated with the axially outer surfaces of each flange piece 52. Furthermore, the portion of the mating surface 54 that is out of phase with the flange piece 52 in the circumferential direction is exposed axially inward and is located axially outward of the axially inner surfaces of the flange pieces 52.

[0104] In addition, in this example, an annular partition space 45a, partitioned on both axial sides, is formed between the opposing surface 44 of the dam portion 42 that constitutes the seal ring 5 and the axial inner surface and overlapping surface 54 of the rotating flange 11a.

[0105] In the case of this example as described above, similarly to the structure of the first example of the embodiment, an intermediate space 47a can be formed between a pair of circumferentially adjacent flange pieces 52, the axially outer side of which is closed by the mating surfaces 54 of the brake rotor 50. Then, a substantially U-shaped rotating airflow can be generated in the intermediate space 47a as the rotating flange 11a rotates.

[0106] As a result, the Karman vortex that is generated on the rear side of the head 23 in the rotation direction of the rotatable flange 11a can be carried by the rotating airflow that is generated with the rotation of the rotatable flange 11a and moved to the partition space 45a. Since the Karman vortex can be prevented from spreading in the axial direction and attenuating, foreign matter such as muddy water can be collected at the center of the Karman vortex, and can be carried by the Karman vortex and discharged radially outward from the rotatable flange 11a. The other configurations and effects are the same as those of the first embodiment.

[0107] Although the embodiments of the present invention have been described above, the technical concept of the present invention is not limited to the structures described in the embodiments. For example, the shape of the dam portion and the number of seal lips constituting the seal ring can be changed as appropriate. Specifically, the dam portion can be composed of a dam portion main body having an annular shape and a cylindrical cover portion that covers the outer peripheral surface of the outer ring, as in the conventional structure described in Patent Document 1. Also, a lip portion that comes into contact with the outer peripheral surface of the outer ring with a tightening margin can be provided on the inner peripheral surface of the cover portion. [Explanation of symbols]

[0108] 1, 1a Hub unit bearing 2 Outer ring 3, 3a hub 4a, 4b Rolling elements 5 Seal ring 6 Studs 7a, 7b Outer raceway 8 Stationary Flange 9 Support hole 10a, 10b Inner raceway 11, 11a Rotating flange 12 Pilot Division 13 Groove shoulder 14 Base 15 Thickness change area 16 Step section 17 Curved section 18 Plane section 19 Thin section 20 Thick wall part 21 Mounting hole 22 Shaft 23 Head 23a End face 24 Male thread 25 Serration section 26 Head body 27 Chamfer 28 Inner Circle 29 Hub wheel 30 Small diameter stepped section 31 Step surface 32 Crimping part 33a, 33b retainer 34 Rolling element installation space 35 Core wire 36 Sealing material 37 Seal fitting cylinder 38 Outward flange 39 Support plate part 40 Seal base 41a~41c Seal lip 42 Weir 43 Gasket part 44 Opposite Surface 45 Partitioned Space 46 Bearing cap 47 Intermediate Space 48 Pressed surface 49 Cutting jig 50 Brake rotor 51 Radial flange part 52 Flange piece 53 Mounting part 54 Overlapping Surface 55 Through hole 56 Center hole 100 Hub unit bearing 101 Rolling element installation space 102 Seal ring 103 Outer Ring 104 Hub 105 Core 106 Sealing material 107 Seal fitting cylinder 108 Outward flange 109 Reinforcement tube 110 Support plate part 111a, 111b, 111c Seal lip 112 Weir 113 Eaves lip 114 Rotating flange 115 Weir body 116 Cover 117 Lip 118 Pressed surface

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 peripheral surface and a rotary flange protruding radially outward at a portion located axially outward of the outer ring; a plurality of rolling elements disposed between the double row outer ring raceways and the double row inner ring raceways so as to be freely rollable; a seal ring having a dam portion that protrudes radially outward beyond the axially outer end portion of the outer ring, and that closes an axially outer opening of a rolling element installation space that exists between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub; a plurality of connecting members for fixing the wheel and the braking rotor to the rotating flange, the rotating flange has a generally circular disk shape as a whole, and has a plurality of thin-walled portions and a plurality of thick-walled portions that protrude axially inward from the thin-walled portions, alternately arranged in a circumferential direction, Each of the plurality of thick-walled portions has an attachment hole through which the connecting member is inserted, Each of the plurality of connecting members has a head portion having a circular contour shape on an outer circumferential surface and abutting against an axially inner surface of the thick-walled portion, the dam portion has an outer diameter that is the same as or slightly smaller than an inscribed circle diameter passing through radially inner ends of each of the plurality of heads, is positioned slightly axially inward of axially inner end faces of the heads, and has a planar opposing surface that faces an axially inner surface of the rotating flange. 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 peripheral surface and a rotary flange protruding radially outward at a portion located axially outward of the outer ring; a plurality of rolling elements disposed between the double row outer ring raceways and the double row inner ring raceways so as to be freely rollable; a seal ring having a dam portion that protrudes radially outward beyond the axially outer end portion of the outer ring, and that closes an axially outer opening of a rolling element installation space that exists between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub; a plurality of connecting members for fixing the wheels and the braking rotors to the rotating flange; a braking rotor having a planar mating surface on an axially inner side surface thereof, the braking rotor being fixed to the rotating flange by the plurality of connecting members with the mating surface overlapping the axially outer side surface of the rotating flange, the rotating flange has a plurality of flange pieces each extending in a radial direction and each having a mounting hole formed therein through which the connecting member is inserted, the connecting member has an outer peripheral surface with a circular contour and a head abutting against an axially inner surface of the flange piece, the dam portion has an outer diameter that is the same as or slightly smaller than an inscribed circle diameter passing through radially inner ends of each of the plurality of heads, is positioned slightly axially inward of axially inner end faces of the heads, and has planar opposing surfaces that face each of the axially inner side surface of the rotating flange and the overlapping surface. Hub unit bearing with braking rotor.

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