Wheel bearing device

Abstract

To provide a bearing device for a wheel which can obtain sufficient fitting force of an auxiliary seal fitted in an exterior member.SOLUTION: A bearing device 1 for a wheel includes an auxiliary seal 7 which fits in an outer diameter surface 2g at the axial outer side of an external member 2. The auxiliary seal 7 has: a core grid 61; and a dam part 72 covering the core grid 61 and formed by an elastic member. The core grid 61 has a fitting part 71a which is formed extending in an axial direction and fitted in an outer diameter surface 2g of the exterior member 2. The dam part 72 is formed in a clump having a thickness from the fitting part 71a to the radial outer side and the axial outer side. A labyrinth structure 73 is formed between the dam part 72 and the interior member 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a wheel bearing device. [Background technology]

[0002] Conventionally, a wheel bearing device that rotatably supports a wheel has been known (see Patent Document 1). In such a wheel bearing device, an outer member is fixed to the vehicle body. An inner member is disposed inside the outer member, and multiple rolling elements are interposed between the raceway surfaces of the outer member and the inner member. In this way, the wheel bearing device forms a rolling bearing structure, allowing a wheel attached to the inner member to rotate freely.

[0003] In such a wheel bearing device, an annular space is formed between the outer member and the inner member. Foreign matter (such as muddy water or dust) may enter the annular space, or the grease sealed in the annular space may leak. For this reason, the wheel bearing device is provided with an inner seal member and an outer seal member to seal both open ends of the annular space. In addition, the hub bearing (wheel bearing device) described in Patent Document 1 is provided with an auxiliary seal fitted to the outer ring (outer member) to more effectively prevent the intrusion of foreign matter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-101750 Summary of the Invention [Problem to be solved by the invention]

[0005] In the hub bearing described in Patent Document 1, the auxiliary seal has a structure that includes a dam portion and a labyrinth seal (labyrinth gap), but does not include a core metal or the like to make it easy to attach and detach. However, the auxiliary seal is not detached in the market, and if the auxiliary seal moves axially toward the hub wheel (outer side) through handling, the auxiliary seal will come into contact with the hub wheel, which is a rotating body, and this will lead to abnormal noise from the bearing and increased rotational friction torque.

[0006] Therefore, the present invention provides a wheel bearing device that can obtain a sufficient fitting force of the auxiliary seal to the outer member. [Means for solving the problem]

[0007] That is, a first invention is a wheel bearing device comprising an outer member having a double-row outer raceway surface formed on its inner circumference, an inner member having a double-row inner raceway surface formed opposite to the double-row outer raceway surface, double-row rolling elements interposed between the raceway surfaces of the outer member and the inner member so as to be rollable, a seal member that closes an open end of an annular space formed by the outer member and the inner member, and an auxiliary seal that fits onto the outer diameter surface of the outer member in the axial direction, wherein the auxiliary seal has a core and a dam portion made of an elastic member that covers the core, and the core has a fitting portion formed to extend in the axial direction and that fits onto the outer diameter surface of the outer member. an inner diameter portion extending radially inward from an axially outer end portion of the fitting portion; and an outer diameter portion extending radially outward from the axially inner end portion of the fitting portion, the dam portion is formed in a block shape having a thickness extending radially outward and axially outward from the fitting portion, the dam portion is formed into a thick-walled shape having a radial thickness greater than a radial length of the outer diameter portion at an outer side in the axial direction, and an axial thickness greater than an axial length of the fitting portion at an outer side in the radial direction, A labyrinth structure is formed between the dam portion and the inner member. [Effects of the Invention]

[0008] The present invention has the following effects.

[0009] That is, according to the first aspect of the present invention, the auxiliary seal is press-fitted and fixed to the outer circumferential surface of the outer member by fitting the core metal to the outer circumferential surface of the outer member, thereby obtaining a sufficient fitting force of the auxiliary seal to the outer member. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. [Figure 2] 3 is a diagram showing an auxiliary seal of the wheel bearing device and its surrounding structure. FIG. [Figure 3] 3 is a diagram showing an auxiliary seal of the wheel bearing device and its surrounding structure. FIG. [Figure 4] 3 is a diagram showing an auxiliary seal of the wheel bearing device and its surrounding structure. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] A wheel bearing device 1 according to the present invention will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view showing the overall structure of the wheel bearing device 1. Figure 2 is a cross-sectional view showing a partial structure of the wheel bearing device 1 according to the first embodiment.

[0012] The wheel bearing device 1 supports a wheel so as to be able to rotate freely. As shown in FIG. 1 , the wheel bearing device 1 includes an outer member 2, an inner member 3, and rolling members 4. In this specification, the "inner side" refers to the vehicle body side of the wheel bearing device 1 when it is attached to the vehicle body, and the "outer side" refers to the wheel side of the wheel bearing device 1 when it is attached to the vehicle body. Furthermore, the "radial outer side" refers to the direction away from the rotation axis R of the inner member 3, and the "radial inner side" refers to the direction approaching the rotation axis R of the inner member 3. Furthermore, the "axial direction" refers to the direction along the rotation axis R of the inner member 3, the "axial outer side" refers to the direction away from the annular space S along the rotation axis R, and the "axial inner side" refers to the direction approaching the annular space S along the rotation axis R.

[0013] The outer member 2 constitutes the outer ring portion of the rolling bearing structure. A fitting surface 2a is formed on the inner periphery at the inner end of the outer member 2. An inner diameter surface (fitting surface) 2b is formed on the outer periphery at the outer end of the outer member 2. Furthermore, two outer raceway surfaces 2c and 2d are formed on the inner periphery at the axial center of the outer member 2. In addition, the outer member 2 is formed with a vehicle body mounting flange 2e that extends radially outward. The vehicle body mounting flange 2e is provided with a plurality of bolt holes 2f.

[0014] The inner member 3 constitutes the inner ring portion of the rolling bearing structure. The inner member 3 is made up of a hub ring 31 and an inner ring 32.

[0015] The hub ring 31 is mounted inside the outer member 2. A small-diameter step 3a is formed on the outer periphery of the inner end of the hub ring 31, extending to the axial center. The small-diameter step 3a refers to the portion of the hub ring 31 where the outer diameter is reduced, and its outer periphery is cylindrical, centered on the rotation axis R. The hub ring 31 also has a spline hole 3b that penetrates from the inner end to the outer end. Furthermore, an inner raceway surface 3d that faces the outer raceway surface 2d is formed on the outer periphery of the hub ring 31 at the axial center. In addition, the hub ring 31 is formed with a wheel mounting flange 3e that extends radially outward. The wheel mounting flange 3e has a plurality of bolt holes 3f formed around the rotation axis R, and hub bolts 33 are press-fitted into each bolt hole 3f.

[0016] The inner ring 32 is fitted onto the small diameter step 3a of the hub ring 31. A fitting surface 3g is formed on the outer circumference of the inner end of the inner ring 32. An inner raceway surface 3c is formed on the outer circumference adjacent to the fitting surface 3g. By fitting the inner ring 32 onto the small diameter step 3a of the hub ring 31, the inner raceway surface 3c is formed on the outer circumference of the hub ring 31, facing the outer raceway surface 2c.

[0017] The rolling members 4 constitute the rolling parts of the rolling bearing structure. The inner rolling member 4 is composed of double-row rolling elements 41 and one cage 42. Similarly, the outer rolling member 4 is also composed of double-row rolling elements 41 and one cage 42.

[0018] The rolling elements 41 are arranged in a circle at equal intervals, each held in a cage 42. The rolling elements 41 constituting the inner-side rolling member 4 are rollably interposed between the outer raceway surface 2c of the outer member 2 and the inner raceway surface 3c of the inner member 3 (inner ring 32). The rolling elements 41 constituting the outer-side rolling member 4 are rollably interposed between the outer raceway surface 2d of the outer member 2 and the inner raceway surface 3d of the inner member 3 (hub ring 31).

[0019] The cage 42 is a ring-shaped body with equally spaced pockets formed therein for accommodating the rolling elements 41. The cage 42 has spherical walls extending between adjacent rolling elements 41, and each rolling element 41 is held between the two spherical walls.

[0020] In addition, the wheel bearing device 1 is provided with an inner seal member 5 and an outer seal member 6 to seal both open ends of the annular space S formed between the outer member 2 and the inner member 3 (hub wheel 31 and inner ring 32). The inner seal member 5 is made up of a slinger 51 and a seal ring 52. The outer seal member 6 is made up of a core metal 61 and an elastic member 62. There are various specifications for the inner seal member 5 and the outer seal member 6, and they are not limited to the specifications disclosed in this specification.

[0021] Here, we will explain the stepped portion 3h formed on the hub wheel 31. The stepped portion 3h refers to the portion that protrudes toward the inner side at the base end of the wheel mounting flange 3e formed on the hub wheel 31. As shown in Figure 2, the flat surface 3i of the stepped portion 3h extends along the radial direction, and a curved surface 3j is formed on the radially inner side thereof, smoothly connecting the flat surface 3i and the axial circumferential surface 3k. The inclined surface 3m of the stepped portion 3h is inclined relative to the radial direction, and extends smoothly from the flat surface 3i to the flat surface 3n of the hub wheel 31.

[0022] The outer seal member 6 is formed by, for example, vulcanization bonding an elastic member 62 to a core metal 61. The core metal 61 has a fitting portion 61a that fits into the inner diameter surface 2b of the outer member 2 and a side plate portion 61b that extends radially inward from the outer end of the fitting portion 61a. The elastic member 62 is formed with a side lip 62a, and the tip of the side lip 62a contacts the flat surface 3i or the curved surface 3j. Furthermore, an intermediate lip 62b is formed radially inward of the side lip 62a, and the tip of the intermediate lip 62b contacts the curved surface 3j. Furthermore, the elastic member 62 is formed with a grease lip 62c, and the tip of the grease lip 62c contacts the shaft circumferential surface 3k.

[0023] Next, the auxiliary seal 7 according to the first embodiment will be described with reference to Figures 2 and 3. The auxiliary seal 7 reduces the intrusion of foreign matter such as muddy water into the outer seal member 6. The auxiliary seal 7 has a core metal 71 and a dam portion 72. Figure 3 is a cross-sectional view showing a partial structure of the wheel bearing device 1 according to the first embodiment.

[0024] The core metal 71 is fitted to an outer diameter surface 2g on the axially outer side of the outer member 2. The core metal 71 is formed, for example, by bending an annular steel plate by press working, to form a fitting portion 71a, an inner diameter portion 71b, and an outer diameter portion 71c. The core metal 71 is preferably made of a stainless steel plate (SUS) or a plated steel plate to prevent corrosion.

[0025] The fitting portion 71a has a cylindrical shape extending in the axial direction. The fitting portion 71a extends along the outer diameter surface 2g of the outer member 2, and the inner diameter surface of the fitting portion 71a fits into the outer diameter surface 2g of the outer member 2. The axial length of the portion of the fitting portion 71a that fits into the outer diameter surface 2g of the outer member 2 is preferably set to, for example, 1.5 mm or more in order to obtain a sufficient fitting force with the outer diameter surface 2g of the outer member 2.

[0026] The inner diameter portion 71b has an annular shape extending radially inward from the axially outer end portion of the fitting portion 71a. The inner diameter portion 71b extends along the axially outer end surface 2h of the outer member 2, and the axially inner end surface of the inner diameter portion 71b abuts against the axially outer end surface 2h of the outer member 2. The cross section of the inner diameter portion 71b and the fitting portion 71a is formed into a substantially L-shape.

[0027] The outer diameter portion 71c has an annular shape extending radially outward from the axially inner end of the fitting portion 71a. The outer diameter portion 71c has a radially outer end face 71e and an axially inner end face 71f. The cross section of the outer diameter portion 71c and the fitting portion 71a is formed into a substantially L-shape.

[0028] The dam portion 72 is made of an elastic member that covers the core metal 71. The dam portion 72 is formed in a block shape that has a thickness extending radially and axially outward from the fitting portion 71a. Specifically, the dam portion 72 is formed in a thick-walled shape such that the radial thickness is greater than the radial length of the outer diameter portion 71c on the axially outer side, and the axial thickness is greater than the axial length of the fitting portion 71a on the radially outer side. Therefore, the dam portion 72 is formed radially outward from the radially outer end 71g of the outer diameter portion 71c on the radially outer side of the fitting portion 71a. Because the dam portion 72 has a block structure rather than a lip structure, it has high robustness against wear and the like. Specifically, the dam portion 72 has a block shape, which provides higher resistance to flying objects than a labyrinth structure formed with a lip shape (thin wall thickness). Furthermore, if a labyrinth structure is formed in a lip shape, the lip will be worn away by muddy water, making it difficult to maintain the labyrinth structure. However, by forming the dam portion 72 in a block shape, the labyrinth structure 73 is maintained even when worn. Therefore, the dam portion 72 is particularly advantageous in maintaining performance over a long period of time. The dam portion 72 is made of synthetic rubber, such as NBR (acrylonitrile-butadiene rubber), and is formed to cover from the radially inner end of the inner diameter portion 71b to the axially outer end of the radially outer end face 71e of the outer diameter portion 71c.

[0029] The dam portion 72 has a protruding portion 72a formed on its radially outer side that protrudes axially outward, and faces the inclined surface 3m and flat surface 3n of the hub wheel 31 across a labyrinth gap L. In other words, the dam portion 72 forms a labyrinth structure 73 between itself and the inner member 3. This allows the dam portion 72 to reduce the intrusion of foreign matter from the outer diameter surface 2g of the outer member 2, the flat surface 3n of the hub wheel 31, etc.

[0030] With this configuration, in the wheel bearing device 1 according to the present invention, the core metal 71 is fitted onto the outer diameter surface 2g of the outer member 2, whereby the auxiliary seal 7 is press-fitted and fixed onto the outer diameter surface 2g of the outer member 2. Therefore, a sufficient fitting force of the auxiliary seal 7 to the outer member 2 can be obtained.

[0031] Furthermore, in the wheel bearing device 1 according to the present invention, the auxiliary seal 7 can be press-fitted and fixed to the outer member 2 by fitting the fitting portion 71a into the outer diameter surface 2g of the outer member 2. Furthermore, the auxiliary seal 7 can be press-fitted into the outer member 2 until the inner diameter portion 71b abuts against the axially outer end surface 2h of the outer member 2, making it easy to control the press-fit position of the auxiliary seal 7. That is, it is easy to control the labyrinth gap L between the dam portion 72 and the inner member 3. Furthermore, the outer diameter portion 71c increases the radial rigidity of the core metal 71, thereby increasing the fitting force of the auxiliary seal 7 with respect to the outer member 2. Additionally, the outer diameter portion 71c blocks muddy water flowing down from the outer diameter surface 2g of the outer member 2 at the axially inner end surface 71f, thereby reducing the intrusion of foreign matter from the outer diameter surface 2g of the outer member 2.

[0032] The dam portion 72 has an axially outer end surface 72b on its radially inner side that extends along the radial direction. The dam portion 72 protrudes axially outward, forming an inner diameter surface 72c at the same radial position as the fitting portion 71a. The axially outer end surface 72d on the radially outer side of the dam portion 72 extends along the radial direction, and a curved surface 72e is formed on the radially inner side, thereby smoothly connecting the inner diameter surface 72c and the axially outer end surface 72d.

[0033] The dam portion 72 has a labyrinth gap L of 0.5 to 1.5 mm between it and the inner member 3. For example, the labyrinth gap L between the axially outer end face 72d of the dam portion 72 and the flat surface 3n of the hub wheel 31, the labyrinth gap L between the curved surface 72e of the dam portion 72 and the inclined surface 3m of the hub wheel 31, and the labyrinth gap L between the axially outer end face 72b of the dam portion 72 and the flat surface 3i of the hub wheel 31 are each 0.5 to 1.5 mm.

[0034] By being configured in this manner, the wheel bearing device 1 of the present invention can prevent the outer member 2 and the hub wheel 31 from coming into close proximity due to the load applied to the wheel bearing device 1, thereby preventing contact between the dam portion 72 and the hub wheel 31, while reducing the intrusion of foreign matter from the outer diameter surface 2g of the outer member 2 and the flat surface 3n of the hub wheel 31, etc.

[0035] The dam portion 72 has a flat surface 72g formed along the axial direction on the outer diameter surface 72f on the outer side in the axial direction. The dam portion 72 has an inclined surface 72h that slopes radially inward from the inner end in the axial direction of the flat surface 72g toward the inner side in the axial direction. The dam portion 72 is formed so that the inclined surface 72h covers up to the outer end in the axial direction of the radially outer end surface 71e of the outer diameter portion 71c.

[0036] With such a configuration, in the wheel bearing device 1 according to the present invention, foreign matter such as muddy water adhering to the inclined surface 72h of the dam portion 72 easily flows inward in the axial direction. Therefore, the intrusion of foreign matter from the outer diameter surface 2g of the outer member 2, the flat surface 3n of the hub ring 31, etc. can be further reduced.

[0037] The dam portion 72 has a protruding portion 72a having an inner diameter surface 72c formed on the outer side in the axial direction of the dam portion 72. The inner diameter surface 72c of the protruding portion 72a is formed to be located radially outside the outer diameter surface 2g on the outer side in the axial direction of the outer member 2. As shown in FIG. 3, when the outer diameter of the outer diameter surface 2g where the auxiliary seal 7 is fitted in the outer member 2 is A, and the inner diameter of the inner diameter surface 72c of the protruding portion 72a is B, A < B. Therefore, a part (in this embodiment, the radially outer end) of the outer end surface 72b in the axial direction of the dam portion 72 is configured to be located on the outer side in the axial direction of the fitting portion 71a.

[0038] With such a configuration, in the wheel bearing device 1 according to the present invention, when the auxiliary seal 7 is press-fitted into the outer member 2, the area of the outer end surface 72b which is the surface to be pressed can be sufficiently ensured. Also, it is possible to apply an external force from the outer side in the axial direction of the fitting portion 71a toward the inner side in the axial direction to the fitting portion 71a. Therefore, it becomes easier to press-fit the auxiliary seal 7 into the outer member 2.

[0039] The inner diameter surface 2b of the outer member 2 is formed so as to be located radially inside the radially inner end portion 72i of the auxiliary seal 7. When the inner diameter of the inner diameter surface 2b of the outer member 2 where the outer side seal member 6 is fitted is C, and the inner diameter of the radially inner end portion 72i of the auxiliary seal 7 is D, C < D. Therefore, the weir portion 72 is configured such that the radially inner end portion 72i does not block the space between the inner diameter surface 2b of the outer member 2 and the flat surface 3i of the hub ring 31.

[0040] With such a configuration, the wheel bearing device 1 according to the present invention can prevent foreign matters such as muddy water from accumulating on the inner diameter surface 2b of the outer member 2 by being blocked by the weir portion 72.

[0041] Next, with reference to FIG. 4, the characteristic points and effects of the wheel bearing device 1 according to the second embodiment will be described. Here, the description will focus mainly on the differences from the wheel bearing device 1 according to the first embodiment. FIG. 4 is a cross-sectional view showing a partial structure of the wheel bearing device 1 according to the second embodiment.

[0042] As shown in FIG. 4, on the outer diameter surface 72f on the outer side in the axial direction of the weir portion 72, a flat surface 72j extending along the axial direction from the axially inner end portion of the inclined surface 72h is formed. The weir portion 72 is formed with a flat surface 72k extending in the radial direction from the axially inner end portion of the flat surface 72j. The weir portion 72 is formed such that the flat surface 72j and the flat surface 72k entirely cover the surface of the outer diameter portion 71c.

[0043] With such a configuration, in the wheel bearing device 1 according to the present invention, since the weir portion 72 covers the surface of the mandrel 71, foreign matters do not come into contact with the mandrel 71. Therefore, a less expensive cold-rolled steel sheet (such as SPCC series according to JIS standards) that does not have rust prevention performance can be used for the mandrel 71.

[0044] The wheel bearing device 1 according to the present invention has a third-generation structure with an inner member rotating specification, which is composed of an outer member 2 having a vehicle body mounting flange 2e and an inner member 3 in which one inner ring 32 is fitted onto a hub ring 31, but is not limited to this. For example, it may also have a third-generation structure with an outer member rotating specification, which is composed of an outer member formed as a hub ring and an inner member in which one inner ring is fitted onto a support shaft having a vehicle body mounting flange. Also, while the example shows a structure in which balls are used for the rolling elements 41, the structure is not limited to this and may also be composed of tapered rollers.

[0045] Finally, the invention in this application is not limited in any way to the embodiments, but is merely illustrative, and can of course be embodied in various forms within the scope that does not deviate from the gist of the present invention. The scope of the invention is indicated by the description of the claims, and further includes all modifications within the meaning and scope of the equivalents described in the claims. [Explanation of symbols]

[0046] 1 Wheel bearing device 2 Outer member 2b Inner surface 2c Outer raceway surface 2d outer raceway 2g outer diameter surface 3 Inner member 3c Inner raceway surface 3d inner raceway surface 31 Hub wheel 32 Inner circle 41 rolling elements 5 Inner seal member (seal member) 6 Outer seal member (seal member) 7 Auxiliary seal 71 Core 71a Fitting part 71b Inner diameter part 71c Outer diameter part 71g radially outer end 72 Weir 72a Protruding part 72c Inner diameter surface 72h slope 72i radially inner end 73 Labyrinth Structure L Labyrinth gap A: Outer diameter of outer surface of outer member B Inner diameter of the inner surface of the protrusion C Inner diameter of inner surface of outer member D Inside diameter of inner radial end of auxiliary seal S Annular Space

Claims

1. an outer member having a double-row outer raceway surface formed on an inner periphery thereof; an inner member having a double-row inner raceway surface formed thereon opposite to the double-row outer raceway surface; double-row rolling elements rollably interposed between the raceway surfaces of the outer member and the inner member; a seal member that closes an open end of an annular space formed by the outer member and the inner member; an auxiliary seal fitted to an outer diameter surface of the outer member in the axial direction, the auxiliary seal has a core metal and a dam portion made of an elastic member covering the core metal, the core metal is formed to extend in the axial direction and has a fitting portion that fits into an outer diameter surface of the outer member, an inner diameter portion that extends radially inward from an axial outer end portion of the fitting portion, and an outer diameter portion that extends radially outward from the axial inner end portion of the fitting portion, the dam portion is formed in a block shape having a thickness extending radially outward and axially outward from the fitting portion, the dam portion is formed into a thick-walled shape having a radial thickness greater than a radial length of the outer diameter portion at an outer side in the axial direction, and an axial thickness greater than an axial length of the fitting portion at an outer side in the radial direction, A wheel bearing device, characterized in that a labyrinth structure is formed between the dam portion and the inner member.

2. A wheel bearing device as described in Claim 1, characterized in that the dam portion is formed radially outward of the fitting portion and protrudes radially outward beyond the radially outer end of the outer diameter portion.

3. 3. The wheel bearing device according to claim 1, wherein a labyrinth gap between the dam portion and the inner member is 0.5 to 1.5 mm.

4. 4. The wheel bearing device according to claim 1, wherein an inclined surface is formed on an outer diameter surface of the dam portion, the inclined surface inclining radially inward from the axially outer side toward the axially inner side.

5. the dam portion has a protruding portion on an axially outward side of the dam portion, the protruding portion having an inner diameter surface formed by the protruding portion protruding axially outward, 5. The wheel bearing device according to claim 1, wherein the outer diameter of the outer diameter surface of the outer member into which the auxiliary seal is fitted is defined as A, and the inner diameter of the inner diameter surface of the protrusion portion is defined as B, and A is less than B.

6. 6. A wheel bearing device according to claim 1, wherein the inner diameter of the inner diameter surface of the outer member into which the seal member is fitted is defined as C, and the inner diameter of the radially inner end of the auxiliary seal is defined as D, and C<D.

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