Sealing device for wheel bearings

Abstract

To provide a seal device for a wheel bearing device provided with a backup seal function to secure sealability without increasing the number of components, and having a structure in which muddy water is hard to accumulate without increasing sliding torque.SOLUTION: A backup seal portion 14d which extends in an axial direction and of which a tip is reduced in diameter toward a radial inner part and is opposed to a vertical plate portion 11b of a slinger 11 through a labyrinth clearance W in a non-contact state, is integrally disposed on a seal member 12, and a drain hole is formed on the backup seal portion 14d, so that intrusion of muddy water from a seal opening can be reduced without increasing the number of components and a flying object and the like does not directly enter the inside of the seal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sealing device for a wheel bearing that rotatably supports a wheel of an automobile or the like relative to a suspension system. [Background technology]

[0002] As shown in FIG. 14, for example, a wheel bearing device includes an outer member 52 having double-row outer raceway surfaces 52a, 52a integrally formed on its inner periphery, an inner member 51 having double-row inner raceway surfaces 54a, 55a formed on its outer periphery that face the double-row outer raceway surfaces 52a, 52a, double-row balls 53, 53 rollably accommodated between the raceway surfaces 54a, 52a and 55a, 52a of the inner member 51 and the outer member 52 via cages 58, 58, and sealing devices 59, 60 attached to openings of an annular space formed between the outer member 52 and the inner member 51.

[0003] BACKGROUND ART Patent Document 1 discloses a seal device for a wheel bearing in which the airtightness of the seal fitting portion is increased and the sealing performance of the seal is improved.

[0004] As shown in Figure 15, at least one of the seal devices 60 in this conventional wheel bearing seal device is composed of a slinger 61 and an annular seal plate 62 arranged opposite each other. The slinger 61 has a cylindrical portion 61a press-fitted into the inner member 51 and a standing portion 61b extending radially outward from the cylindrical portion 61a. The seal plate 62 is composed of a core 63 press-fitted onto the inner periphery of the end of the outer member 52, and a seal member 64 joined to the core 63 by vulcanization bonding. The seal member 64 has a pair of side lips 64a, 64b extending radially outward at an angle and in sliding contact with the standing portion 61b of the slinger 61 via a predetermined axial interference, and a grease lip 64c extending radially inward at an angle and in sliding contact with the cylindrical portion 61a of the slinger 61 via a predetermined radial interference. A backup seal 65 is attached to the bearing outer side of the seal device 60.

[0005] This backup seal 65 has a cylindrical core 65a that is pressed into the inner circumference of the end of the outer member 52, and a seal lip 65b that is joined to this core 65a by vulcanization bonding and extends at an inclination radially inward, and the seal lip 65b is in sliding contact with the upright portion 61b of the slinger 61 via a predetermined axial interference, thereby preventing rainwater, dust, etc. from directly entering the sealing device 60.

[0006] Furthermore, since the backup seal 65 is attached to the inner periphery of the end without protruding from the outer member 52, it will not be damaged by collisions with flying debris, and will not interfere with other parts during transportation or assembly, allowing the seal device to exhibit its inherent sealing properties, and further increasing the airtightness of the fitting portion of the seal device, thereby improving the sealing performance of the seal device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-69420 Summary of the Invention [Problem to be solved by the invention]

[0008] However, attaching the backup seal 65, which is a separate part from the sealing device 60, to the outer side of the bearing of the sealing device 60 increases the number of parts, which leads to an increase in costs.

[0009] Furthermore, sliding the backup seal 65 against the sealing device 60 to ensure sealing performance increases torque. In addition, heat generated during sliding increases internal pressure between the seal lip 65b of the backup seal 65 and the side lip 64a of the sealing device 60, and if internal air leaks from the sliding contact portion of the seal lip 65b of the backup seal 65, muddy water or the like may enter from the outside.

[0010] Furthermore, since the sealing device 60 does not have a drainage function, if muddy water enters the sealing device 60, the muddy water will continue to accumulate inside the seal, causing the lip rubber to deteriorate and leading to malfunction.

[0011] Therefore, this invention aims to provide a sealing device for wheel bearings that has a backup seal function to ensure sealing performance without increasing the number of parts, does not increase sliding torque, and is designed so that muddy water does not easily accumulate inside. [Means for solving the problem]

[0012] The wheel bearing device of the present invention that solves the above-mentioned problems is provided with an outer member having a double-row outer raceway surface integrally formed on its inner periphery, an inner member having a double-row inner raceway surface formed on its outer periphery that faces the double-row outer raceway surface, and double-row rolling elements housed between the raceway surfaces of the inner member and the outer member via a cage so as to be able to roll freely, and in this wheel bearing seal device that is mounted on both ends of an annular space formed between the outer member and the inner member, at least one of the seal devices is composed of a slinger and an annular seal plate that are arranged opposite each other, and the slinger has a cylindrical portion that is press-fitted into the inner member. and a standing plate portion extending radially outward from the cylindrical portion, the sealing plate consisting of a core bar pressed into the inner periphery of the end of the outer member and a sealing member integrally joined to the core bar by vulcanization bonding, the sealing member having a pair of side lips extending at an incline radially outward, a grease lip on the inner diameter side thereof extending at an incline toward the inside of the bearing, and a backup seal portion extending axially from the end of the cylindrical portion of the core bar and having a tip which tapers radially inward, the tip of the backup seal portion facing the standing plate portion of the slinger or an encoder provided on the standing plate portion of the slinger via a labyrinth gap.

[0013] The backup seal portion is preferably provided with drainage holes on the circumference.

[0014] Furthermore, before the backup seal portion is pressed into a predetermined position in the opening of the annular space formed between the outer member and the inner member 1, it spreads outward in the radial direction, extends axially while curving through a large-diameter bend point, and its tip is located on the larger-diameter side of the axial extension line of the outer diameter of the cylindrical portion of the core bar.When the core bar is pressed into the inner circumference of the end of the outer member, the large-diameter bend point is pushed toward the inner diameter by the inner circumference of the end of the outer member, causing the backup seal portion to reduce in diameter, and the tip of the backup seal portion can be arranged to face the upright portion of the slinger or an encoder provided on the upright portion of the slinger through a labyrinth gap.

[0015] Furthermore, it is desirable to provide a recessed groove on the inner peripheral surface of the end portion of the outer member into which the large-diameter bending point of the backup seal portion fits when the core metal is pressed into the inner peripheral surface of the end portion of the outer member.

[0016] It is desirable that the backup seal portion be provided with axial cuts at several locations in the circumferential direction.

[0017] The axial cut is preferably in the shape of a V-shape that widens towards the tip. [Effects of the Invention]

[0018] As described above, in the wheel bearing sealing device of the present invention, the backup seal portion formed integrally with the seal member extends in the axial direction, with its tip tapering radially inward, and its tip facing the encoder on the upright portion of the slinger or the side surface of the upright portion without contact via the labyrinth gap W, thereby reducing the intrusion of muddy water through the seal opening and preventing flying objects and the like from directly entering the interior of the seal.

[0019] Furthermore, since the backup seal portion is formed integrally with the side lip and grease lip of the seal member, there is no increase in the number of parts as in the conventional case.

[0020] Furthermore, since the backup seal portion faces the upright portion of the slinger or the encoder on the side of the upright portion without contacting it, there is no increase in torque and no increase in internal pressure due to heat.

[0021] Furthermore, by providing a drainage hole in the backup seal, it becomes difficult for muddy water to accumulate inside the seal, which also helps prevent deterioration of the lip rubber. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a longitudinal sectional view showing an embodiment of a seal device for a wheel bearing of the present invention. [Figure 2] 3 is a partially enlarged view showing an inner sealing portion of the wheel bearing seal device of the present invention; FIG. [Figure 3] 4 is a longitudinal sectional view showing a state in which an inner seal in the wheel bearing seal device of the present invention is press-fitted using a seal press-fitting jig; FIG. [Figure 4] 3 is a longitudinal sectional view of an inner seal in the wheel bearing seal device of the present invention. FIG. [Figure 5] FIG. 5 is an enlarged view of the rectangular portion X in FIG. 4. [Figure 6] 1 is a longitudinal sectional view showing an initial state in which an inner seal in a seal device for a wheel bearing of the present invention is press-fitted using a seal press-fitting jig; [Figure 7] 1 is a longitudinal sectional view showing a state in which an inner seal in a seal device for a wheel bearing of the present invention is being press-fitted using a seal press-fitting jig; [Figure 8] 3 is a right side view of an inner seal in the wheel bearing seal device of the present invention. FIG. [Figure 9] 4 is a bottom view of an inner seal in the wheel bearing seal device of the present invention. FIG. [Figure 10] 4 is an enlarged view showing a cut portion of a backup seal portion in the wheel bearing seal device of the present invention. FIG. [Figure 11] FIG. 5 is a cross-sectional view taken along line ZZ in FIG. [Figure 12]4 is a partial enlarged view of a backup seal portion on the road surface side before an inner seal in the wheel bearing seal device of the present invention is press-fitted into a predetermined position. FIG. [Figure 13] 4 is a partial enlarged view of a backup seal portion on the road surface side after an inner seal in the wheel bearing seal device of the present invention has been press-fitted into a predetermined position; FIG. [Figure 14] FIG. 10 is a longitudinal sectional view showing a conventional seal device for a wheel bearing. [Figure 15] 15 is a partially enlarged view showing an inner sealing portion of the wheel bearing seal device of FIG. 14. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the side that is closer to the outside of the vehicle when assembled to the vehicle will be referred to as the outer side (left side in FIG. 1), and the side that is closer to the center will be referred to as the inner side (right side in FIG. 1).

[0024] The wheel bearing device shown in Figure 1 is for a driving wheel known as the third generation, and comprises an inner member 1, an outer member 2, and double rows of balls 3, 3 housed between the two members 1, 2 so that they can roll freely.

[0025] The inner member 1 is made up of a hub ring 4 and an inner ring 5 press-fitted and fixed to the hub ring 4.

[0026] The hub wheel 4 has a wheel mounting flange 6 integrally formed at one end for mounting the wheel, an inner raceway surface 4a on the outer periphery, and a cylindrical small diameter step 4b extending axially from this inner raceway surface 4a, and serrations (or splines) 4c for transmitting torque formed on the inner periphery.

[0027] Hub bolts 7 are also installed at equally spaced positions around the wheel mounting flange 6. The inner ring 5 has an inner side rolling surface 5a formed on its outer circumference, and is press-fitted into the small diameter stepped portion 4b of the hub ring 4 via a specified interference.

[0028] The outer member 2 has integrally formed on its outer periphery a vehicle body mounting flange 2b for attachment to a knuckle (not shown) that constitutes the suspension system, and has integrally formed on its inner periphery double row outer raceway surfaces 2a, 2a that face the inner raceway surfaces 4a, 5a of the inner member 1. Double row balls 3, 3 are housed between these two raceway surfaces 4a, 2a and 5a, 2a via a cage 8 so that they can roll freely.

[0029] Seal devices 9, 10 are attached to both ends of the outer member 2, sealing the opening of the annular space formed between the outer member 2 and the inner member 1. These seal devices 9, 10 prevent the lubricating grease sealed inside the bearing from leaking out and prevent rainwater, dust, etc. from entering the inside of the bearing from the outside.

[0030] Here, the inner seal 10 of the sealing devices 9, 10 is configured as a so-called pack seal, consisting of a slinger 11 and an annular seal plate 12 arranged opposite each other, as shown enlarged in Figure 2. The slinger 11 is formed into an overall annular shape with a roughly L-shaped cross section by pressing from a ferritic stainless steel plate (JIS standard SUS430 series, etc.), an austenitic stainless steel plate (JIS standard SUS304 series, etc.), or a rust-proofed cold-rolled steel plate (JIS standard SPCC series, etc.), and is composed of a cylindrical portion 11a that is press-fitted into the inner ring 5, and an upright portion 11b that extends radially outward from the cylindrical portion 11a.

[0031] On the other hand, the seal plate 12 is formed in a generally annular shape with a generally L-shaped cross section, and is attached to the outer member 2. This seal plate 12 comprises a core 13 and a seal member 14 vulcanization-bonded to this core 13. The core 13 is formed by pressing an austenitic stainless steel plate (JIS standard SUS304, etc.) or a rust-proofed cold-rolled steel plate (JIS standard SPCC, etc.), and comprises a cylindrical portion 13a fitted into the end of the outer member 2, and a standing portion 13b extending radially inward from this cylindrical portion 13a.

[0032] The sealing member 14 is made of synthetic rubber such as NBR (acrylonitrile-butadiene rubber), and has a pair of side lips 14a, 14b that extend radially outward at an incline, a grease lip 14c on the inner diameter side of these that extends at an incline toward the inside of the bearing, and a backup seal portion 14d that extends axially from the end of the cylindrical portion 13a of the core metal 13 and has a tip that tapers radially inward.

[0033] The side lips 14a, 14b are in sliding contact with the outer side surface of the upright portion 11b of the slinger 11 via a predetermined axial interference, and the grease lip 14c is in sliding contact with the cylindrical portion 11a via a radial interference.

[0034] Additionally, the tip of backup seal portion 14d faces, without contact, upright portion 11b of slinger 11 via labyrinth gap W. In the embodiment shown in Figures 1 and 2, encoder 15 is provided on the inner side surface of upright portion 11b of slinger 11, so the tip of backup seal portion 14d faces, without contact, the side surface of encoder 15 via labyrinth gap W.

[0035] The end of the cylindrical portion 13a of the core metal 13 is formed thinner and has a reduced diameter than the other portions. A backup seal portion 14d is secured to the outer surface of the end of the cylindrical portion 13a, thereby strengthening the securing force of the seal member 14 and enabling the airtightness of the fitting portion with the outer member 2 to be maintained for a long period of time.

[0036] The backup seal portion 14d extends in the axial direction, with its tip tapering radially inward, and its tip facing the upright portion 11b of the slinger 11 or the encoder 15 on the side of the upright portion 11b without contact through the labyrinth gap W, thereby reducing the intrusion of muddy water through the seal opening and preventing flying objects and the like from directly entering the inside of the seal.

[0037] Furthermore, since the backup seal portion 14d is formed integrally with the side lips 14a, 14b and the grease lip 14c, the number of parts does not increase as in the conventional case.

[0038] Furthermore, since the backup seal portion 14d faces the upright portion 11b of the slinger 11 or the encoder 15 on the side of the upright portion 11b without contacting it, there is no increase in torque and no increase in internal pressure due to heat.

[0039] As shown in Figure 3, the sealing device 10 is pressed into the opening of the annular space formed between the outer member 2 and the inner member 1 from the inner side toward the outer side using a seal pressing jig 16, and the backup seal portion 14d formed by this pressing and expanding radially outward is pressed against the inner surface of the end of the outer member 2, reducing its diameter and being designed to face the standing plate portion 11b of the slinger 11 or the encoder 15 on the side of the standing plate portion 11b without contacting it.

[0040] The seal press-fitting jig 16 consists of an outer cylindrical portion 16a fixed to the end of the outer member 2 and an inner cylindrical portion 16b located inside the outer cylindrical portion 16a and movable in the axial direction. The seal 10 is pushed axially by the inner cylindrical portion 16b and press-fit into the opening of the annular space formed between the outer member 2 and the inner member 1.

[0041] FIG. 4 shows the seal 10 in a state before it is press-fitted into the opening of the annular space formed between the outer member 2 and the inner member 1, and FIG. 5 is an enlarged view of the X portion of FIG.

[0042] As shown in Figure 5, before the backup seal portion 14d is pressed into a predetermined position in the opening of the annular space formed between the outer member 2 and the inner member 1, it spreads outward in the radial direction and extends in the axial direction while curving through a bending point 14e, with its tip 14f located on the larger diameter side than the axial extension line of the outer diameter d of the cylindrical portion 13a of the core bar 13, leaving a gap s between the axial extension line of the core bar 13 and the tip 14f of the backup seal portion 14d.

[0043] As shown in Figure 6, the outer diameter of the inner cylindrical portion 16b of the seal press-fitting jig 16 and the outer diameter d of the cylindrical portion 13a of the core wire 13 are the same diameter, and when the inner cylindrical portion 16b of the seal press-fitting jig 16 is pressed against the side of the seal 10, the tip 14f of the backup seal portion 14d is located on the outer diameter side of the inner cylindrical portion 16b, creating a gap s between the outer diameter of the inner cylindrical portion 16b and the inner diameter of the tip 14f of the backup seal portion 14d, so that the seal device 10 can be pressed in axially by the inner cylindrical portion 16b of the seal press-fitting jig 16 without being obstructed by the backup seal portion 14d.

[0044] Then, as the seal 10 is pressed in axially by the inner cylindrical portion 16b of the seal press-fitting jig 16, the bending point 14e located on the largest diameter side of the backup seal portion 14d comes into contact with the inner peripheral surface of the end portion of the outer member 2, as shown in Figure 7, and as the seal is pressed in, the tip portion from the bending point 14e contracts inward and bends until it is pressed in to a predetermined position, as shown in Figure 2, the tip 14f of the backup seal portion 14d faces the side of the encoder 15 if there is one, or faces the upright portion 11b of the slinger 11 via a labyrinth gap w if there is no encoder 15.

[0045] Labyrinth gap w is 0 <w<1[mm]としている。

[0046] As described above, the backup seal portion 14d reduces in diameter toward the inner diameter as the seal device 10 is pressed axially by the inner cylindrical portion 16b of the seal press-fitting jig 16, so a recess 16c is provided on the outer periphery of the tip of the inner cylindrical portion 16b to accommodate the bending backup seal portion 14d.

[0047] Further, the inner peripheral surface of the end portion of the outer member 2 is provided with a recessed groove 2c into which a bending point 14e of the maximum diameter portion of the backup seal portion 14d fits.

[0048] The thickness of the rubber of the backup seal portion 14d is 0.3 to 1.5 mm.

[0049] The backup seal portion 14d, which is expanded radially outward before press-fitting, shrinks inward as the seal is pressed in. Therefore, to facilitate this shrinkage, it is desirable to make axial cuts 14g in several locations around the circumference, as shown in Figures 8 and 9.

[0050] In the example of FIGS. 8 and 9, eight cuts 14g are provided in the circumferential direction.

[0051] The notch 14g also has the effect of making it easier for the backup seal portion 14d to narrow into a circular shape, and preventing deformation of the backup seal portion 14d after press-fitting.

[0052] The notch 14g is preferably formed in a figure eight shape with an open tip as shown in FIG. 10 so that it closes when the backup seal portion 14d is narrowed into a circular shape.

[0053] The backup seal portion 14d extends toward the inner diameter so as to close the seal opening when the seal 10 is pressed into the opening of the annular space formed between the outer member 2 and the inner member 1, thereby reducing the intrusion of muddy water and preventing flying objects and the like from directly entering the inside of the seal.

[0054] This backup seal portion 14d faces the upright portion 11b of the slinger 11 or the encoder 15 on the side of the upright portion 11b without contact through a labyrinth gap w, so there is a possibility that muddy water may enter the inside of the backup seal portion 14d through the labyrinth gap w.

[0055] For this reason, it is desirable to provide a drain hole 14h at a bending point 14e of the maximum diameter portion of the backup seal portion 14d, as shown in FIGS.

[0056] FIG. 11 shows an example in which three drainage holes 14h are provided on the road surface side of the backup seal portion 14d, and the opening angle θ of the drainage holes 14h in the circumferential direction is set to 0<θ<180°.

[0057] 12 shows the drain hole 14h portion of the backup seal portion 14d before the seal device 10 is press-fitted, and FIG. 13 shows the drain hole 14h portion of the backup seal portion 14d after the seal device 10 is press-fitted.

[0058] The present invention is not limited to the above-described embodiments, and can of course be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims. [Industrial Applicability]

[0059] The seal device for a wheel bearing according to the present invention can be applied to first to fourth generation wheel bearing devices. [Explanation of symbols]

[0060] 1: Inner member 2: Outer member 2a: Outside raceway 2c: Groove 3: Ball 4: Hub wheel 4a: Inner rolling surface 5: Inner circle 5a: Inner rolling surface 6: Wheel mounting flange 8: Retainer 9, 10: Sealing device 11: Slinger 11a: Cylindrical part 11b: Standing board section 12: Seal plate 13: Core 14a, 14b: Side lip 14c: Grease Lip 14d: Backup seal part 14e: Bend point 14f: Tip 14g: cut 14h: Drain hole 15: Encoder

Claims

1. In a wheel bearing comprising an outer member having double-row outer raceway surfaces integrally formed on its inner periphery, an inner member having double-row inner raceway surfaces formed on its outer periphery opposite the double-row outer raceway surfaces, and double-row rolling elements housed between the raceway surfaces of the inner member and the outer member via a cage so as to be able to roll freely, a seal device for a wheel bearing is attached to both ends of an annular space formed between the outer member and the inner member, wherein at least one of the seal devices is comprised of a slinger and an annular seal plate arranged opposite each other, the slinger having a cylindrical portion press-fitted into the inner member and a standing plate portion extending radially outward from the cylindrical portion, the seal plate comprising a core metal press-fitted into the inner periphery at the end of the outer member and a seal member integrally joined to the core metal by vulcanization adhesion, the seal member having a pair of side walls extending radially outward at an angle a drip, a grease slip on the inner diameter side thereof extending at an angle towards the inside of the bearing, and a backup seal portion extending axially from the end of the cylindrical portion of the core bar with its tip tapering radially inward, wherein before the backup seal portion is press-fitted into a predetermined position in an opening of an annular space formed between the outer member and the inner member, the backup seal portion expands radially outward and extends axially while curving past a bend point at a large diameter, with its tip located on the larger diameter side of an axial extension of the outer diameter of the cylindrical portion of the core bar, and when the core bar is press-fitted into the inner periphery of the end of the outer member, the bend point at the large diameter is pushed inward by the inner periphery of the end of the outer member, causing the backup seal portion to be tapered, and the tip of the backup seal portion faces the upright portion of the slinger or an encoder provided on the upright portion of the slinger via a labyrinth gap.

2. 2. A seal device for a wheel bearing according to claim 1, wherein drain holes are provided on the circumference of said backup seal portion.

3. 3. A sealing device for a wheel bearing according to claim 1, wherein a recessed groove is provided on the inner peripheral surface of the end portion of the outer member into which a large-diameter bending point of the backup seal portion fits when the core metal is press-fitted into the inner peripheral surface of the end portion of the outer member.

4. 4. The seal device for a wheel bearing according to claim 3, wherein the backup seal portion is provided with axial cuts at several positions in the circumferential direction.

5. 5. A seal device for a wheel bearing according to claim 4, wherein the axial cut is in a V-shape that widens toward the tip end.

6. A wheel bearing equipped with the seal device for a wheel bearing according to any one of claims 1 to 5.

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