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. A step part 2h protruding to the radial outer side is formed on the outer diameter surface 2g at the axial outer side of the exterior member 2. The auxiliary seal 7 has a slinger 71. The slinger 71 has: a fitting part 71a which is formed extending in an axial direction at a radial inner end of the slinger 71 and fitted in the outer diameter surface 2g of the exterior member 2; and an axial inner bending part 71b extending from an axial inner end of the fitting part 71a to the radial outer side. The axial inner end 7b of the auxiliary seal 7 is butted with the step part 2h, and an axial outer end 7a of the auxiliary seal 7 forms a labyrinth structure 73 with an internal 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 for closing an open end of an annular space formed by the outer member and the inner member, and an auxiliary seal fitted to an outer diameter surface on the axially outer side of the outer member, The auxiliary seal has a slinger, the slinger is formed to extend in the axial direction at the radially inner end of the slinger, and has a fitting portion that fits onto the outer diameter surface of the outer member, and an axially inner bent portion that extends radially outward from the axially inner end of the fitting portion, the axially inner end of the auxiliary seal abuts against the step portion, and the axially outer end of the auxiliary seal forms a labyrinth structure between the auxiliary seal 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 diameter surface of the outer member by fitting the slinger to the outer diameter 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. [Figure 5] 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 A of the inner member 3, and the "radial inner side" refers to the direction approaching the rotation axis A of the inner member 3. Furthermore, the "axial direction" refers to the direction along the rotation axis A of the inner member 3, the "axial outer side" refers to the direction away from the annular space S along the rotation axis A, and the "axial inner side" refers to the direction approaching the annular space S along the rotation axis A.

[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. A 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. A plurality of bolt holes 2f are formed in the vehicle body mounting flange 2e.

[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 A. 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 A, and hub bolts 33 are press-fitted into each of the bolt holes 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 fitting 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. A side lip 62a is formed on the elastic member 62, and a tip of the side lip 62a contacts the flat surface 3i or the curved surface 3j. An intermediate lip 62b is formed radially inward of the side lip 62a, and a tip of the intermediate lip 62b contacts the curved surface 3j. Furthermore, a grease lip 62c is formed on the elastic member 62, and a tip of the grease lip 62c contacts the shaft circumferential surface 3k.

[0023] The outer member 2 has a step portion 2h formed on its outer diameter surface 2g on the outer side. The step portion 2h refers to a portion that protrudes radially outward on the axially inner side of the flat surface 2i of the outer member 2. The flat surface 2i of the outer member 2 extends along the axial direction, and a curved surface 2j is formed on the axially inner side thereof, thereby smoothly connecting the flat surface 2i and the axially outer end surface 2k of the step portion 2h. The axially outer end surface 2k of the step portion 2h extends radially and is connected to the outer diameter surface 2m that extends in the axial direction.

[0024] Next, the auxiliary seal 7 according to the first embodiment will be described with reference to Fig. 2. 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 slinger 71.

[0025] The slinger 71 is fitted to the outer diameter surface 2g on the axially outer side of the outer member 2. The slinger 71 is formed, for example, by bending an annular steel plate by press working, to form a fitting portion 71a and an axially inner bent portion 71b. The slinger 71 is preferably made of a stainless steel plate (SUS) or a plated steel plate to prevent corrosion.

[0026] The fitting portion 71a is cylindrical and extends axially at the radially inner end of the slinger 71. The fitting portion 71a extends along the flat surface 2i of the outer member 2, and the inner diameter surface of the fitting portion 71a fits into the flat surface 2i of the outer member 2. The axially outer end of the fitting portion 71a is located axially outward of the axially outer end surface 2n of the outer member 2. The axially outer end of the fitting portion 71a (the axially outer end 7a of the auxiliary seal 7) forms a labyrinth structure 73 between itself and the inclined surface 3m (inner member 3) of the hub wheel 31. The axial length of the portion of the fitting portion 71a that fits into the flat surface 2i of the outer member 2 is preferably set to, for example, 1.5 mm or more in order to obtain a fitting force against the flat surface 2i of the outer member 2.

[0027] The axially inner bent portion 71b has an annular shape extending radially outward from the axially inner end portion of the fitting portion 71a. The axially inner bent portion 71b has a substantially L-shaped cross section with the fitting portion 71a, and an axially inner end face 71c (axially inner end face 7b of the auxiliary seal 7) abuts against an axially outer end face 2k of the stepped portion 2h.

[0028] With this configuration, in the wheel bearing device 1 according to the present invention, the auxiliary seal 7 is press-fitted and fixed to the outer diameter surface 2g of the outer member 2 by fitting the slinger 71 to 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.

[0029] 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. The fitting portion 71a has a simple shape extending in the axial direction, and a labyrinth structure 73 can be formed between the fitting portion 71a and the hub wheel 31. Furthermore, the auxiliary seal 7 can be press-fitted into the outer member 2 until the axially inner bent portion 71b abuts against the axially outer end surface 2k of the stepped portion 2h, ensuring reliable positioning of the auxiliary seal 7. This facilitates management of the labyrinth gap L between the slinger 71 and the hub wheel 31. Additionally, the axially inner bent portion 71b increases the radial rigidity of the slinger 71, thereby increasing the fitting force of the slinger 71 to the outer member 2. Furthermore, the axially inner bent portion 71b can block foreign matter that flows down from the outer diameter surface 2m of the stepped portion 2h at its axially inner end surface 71c. As a result, the axially inner bent portion 71b can reduce the intrusion of foreign matter from the outer diameter surface 2m of the stepped portion 2h.

[0030] The slinger 71 faces the inclined surface 3m of the hub wheel 31 via a labyrinth gap L. In other words, the slinger 71 forms a labyrinth structure 73 with the inclined surface 3m of the hub wheel 31. For example, the labyrinth gap L between the slinger 71 (auxiliary seal 7) and the hub wheel 31 (inner member 3) is 0.5 to 1.0 mm. Specifically, the labyrinth gap L between the axially outer end of the fitting portion 71a and the inclined surface 3m of the hub wheel 31 is 0.5 to 1.0 mm.

[0031] 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 slinger 71 and the hub wheel 31, while reducing the intrusion of foreign matter from the outer diameter surface 2m of the step portion 2h and the flat surface 3n of the hub wheel 31, etc.

[0032] Next, the features and effects of the wheel support bearing device 1 according to the second embodiment will be described with reference to Fig. 3. Here, the description will focus mainly on the differences from the wheel support bearing device 1 according to the first embodiment. Fig. 3 is a cross-sectional view showing a partial structure of the wheel support bearing device 1 according to the second embodiment.

[0033] The dam portion 72 is made of an elastic member that covers the slinger 71. As shown in FIG. 3 , the dam portion 72 is formed in a block shape that has a thickness extending radially outward 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 axially outer side of the axially inner bent portion 71b and the axial thickness is greater than the axial length of the radially outer side of the fitting portion 71a. Therefore, the dam portion 72 is formed radially outward from the fitting portion 71a beyond the radially outer end 71h of the axially inner bent portion 71b. 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 using a lip, 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 the area from the axially outer end of the fitting portion 71a to the radially outer end of the axially inner bent portion 71b. The dam portion 72 faces the inclined surface 3m of the hub wheel 31 across the labyrinth gap L. This allows the dam portion 72 to reduce the intrusion of foreign matter from the outer diameter surface 2m of the stepped portion 2h and the flat surface 3n of the hub wheel 31.

[0034] The dam portion 72 has an axially outer end surface 72a that extends radially. The dam portion 72 also has an outer diameter surface 72b that extends axially, and the axially outer end surface 72a and the outer diameter surface 72b are connected. The dam portion 72 has a cross-sectional shape that, when combined with the slinger 71, is substantially rectangular. This forms a labyrinth structure 73 between the dam portion 72 and the hub wheel 31. Furthermore, the dam portion 72 is configured so that the dam height B of the dam portion 72 is higher than the dam height C of the axially inner bent portion 71b, making it difficult for foreign matter to flow from the outer diameter surface 2m of the step portion 2h toward the inside in the axial direction.

[0035] With this configuration, the wheel bearing device 1 according to the present invention has enhanced functions of the dam and labyrinth, thereby improving the function of blocking foreign matter flowing down from the outer diameter surface 2m of the step portion 2h and further reducing the intrusion of foreign matter through the labyrinth gap L.

[0036] Next, the features and effects of the wheel support bearing device 1 according to the third embodiment will be described with reference to Fig. 4. Here again, the description will focus mainly on the differences from the wheel support bearing device 1 according to the first embodiment. Fig. 4 is a cross-sectional view showing a partial structure of the wheel support bearing device 1 according to the third embodiment.

[0037] 4, the dam portion 72 has a flat surface 72d extending along the axial direction formed on the axially outer side of the outer diameter surface 72c. The dam portion 72 has an inclined surface 72e that slopes radially inward from the axially inner end of the flat surface 72d toward the axially inner side. The dam portion 72 is formed so that the inclined surface 72e covers the axially outer end of the radially outer end surface 71d of the axially inner bent portion 71b.

[0038] With this configuration, the wheel bearing device 1 according to the present invention allows foreign matter such as muddy water adhering to the inclined surface 72e of the weir portion 72 to easily flow inward in the axial direction. This further reduces the intrusion of foreign matter from the outer diameter surface 2m of the stepped portion 2h and the flat surface 3n of the hub wheel 31.

[0039] The dam portion 72 has an axially outer end face 72f on its radially outer side that extends along the radial direction. An inclined surface 72g is formed at the radially inner end of the axially outer end face 72f. The inclined surface 72g is inclined relative to the radial direction and smoothly connects from the axially outer end face 72f to the radially inner end of the axially outer end face 71e of the fitting portion 71a. For example, the labyrinth gap L between the axially outer end face 72f of the dam portion 72 and the flat surface 3n of the hub wheel 31, and the labyrinth gap L between the inclined surface 72g of the dam portion 72 and the inclined surface 3m of the hub wheel 31 are both 0.5 to 1.0 mm, which are the above-mentioned dimensions.

[0040] By being configured in this manner, the wheel bearing device 1 according to the present invention has a labyrinth structure 73 formed therein, which has a labyrinth gap L of the above-mentioned dimension from the radially outer side to the radially inner side of the dam portion 72. This strengthens the labyrinth function of the dam portion 72, and can further reduce the intrusion of foreign matter through the labyrinth gap L.

[0041] Next, the features and effects of the wheel support bearing device 1 according to the fourth embodiment will be described with reference to Fig. 5. Here again, the description will mainly focus on the differences from the wheel support bearing device 1 according to the first embodiment. Fig. 5 is a cross-sectional view showing a partial structure of the wheel support bearing device 1 according to the fourth embodiment.

[0042] 5, the slinger 71 has an axially outer bent portion 71f, which can block foreign matter that flows down from the outer diameter surface of the fitting portion 71a at its axially inner end surface 71g.

[0043] The axially outer bent portion 71f has an annular shape extending radially outward from the axially outer end portion of the fitting portion 71a. The axially outer bent portion 71f has a substantially L-shaped cross section when combined with the fitting portion 71a, and is located axially outward from the axially outer end face 2n of the outer member 2, forming a labyrinth structure 73 between itself and the hub wheel 31. Note that the axially outer bent portion 71f is formed so that its weir height D is higher than the weir height E of the axially inner bent portion 71b, but this is not particularly limited, and the weir height D may be lower than the weir height E of the axially inner bent portion 71b.

[0044] With this configuration, the wheel bearing device 1 according to the present invention has enhanced functions of the dam and labyrinth, thereby improving the function of blocking foreign matter flowing down from the outer diameter surface 2m of the step portion 2h and reducing the intrusion of foreign matter through the labyrinth gap L.

[0045] 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.

[0046] 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]

[0047] 1 Wheel bearing device 2 Outer member 2c Outer raceway surface 2d outer raceway 2g outer diameter surface 2h step part 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 7a Axial outer end 7b Axial inner end 71 Slinger 71a Fitting part 71b Axial inner bend 71f Axial outer bend 71h Radial outer end 72 Weir 72c Outer diameter surface 72e Slope L Labyrinth gap 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; A wheel bearing device including an auxiliary seal fitted to an outer diameter surface on the axially outer side of the outer member, a stepped portion protruding radially outward is formed on an outer diameter surface of the outer member in the axial direction, The auxiliary seal has a slinger, and the slinger has a fitting portion formed at a radially inner end portion of the slinger to extend in the axial direction and fitted to an outer diameter surface of the outer member, and an axially inner bent portion extending radially outward from the axially inner end portion of the fitting portion, an axially inner end portion of the auxiliary seal abuts against the stepped portion, an axially outer end portion of the auxiliary seal forms a labyrinth structure between the auxiliary seal and the inner member; The auxiliary seal is The slinger further includes a dam portion made of an elastic member that covers the slinger. the dam portion is formed in a block shape having a thickness extending radially outward and axially outward from the fitting portion, and is formed radially outward at the radially outer side of the fitting portion so as to protrude radially outward beyond the radially outer end of the axially inner bent portion.

2. 2. The wheel bearing device according to claim 1, wherein a labyrinth gap between the auxiliary seal and the inner member is 0.5 to 1.0 mm.

3. 3. 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.

4. 4. The wheel bearing device according to claim 1, wherein the slinger has an axially outer bent portion that extends radially outward from an axially outer end of the fitting portion.

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