Sealing device for wheel bearing device and wheel bearing device equipped with same

Abstract

To provide a wheel bearing device capable of suppressing increase of torque due to negative pressure generated between lips.SOLUTION: In a sealing device 5 of a wheel bearing device 1, an elastic member 55 is formed with a plurality of lips including two side lips 551, 552, and a projection part 554 projecting axially inward from the opposite side of an inner plate part 542 with respect to the two side lips 551, 552. Of the two side lips 551, 552, the radially inward side lip 522 is in slide contact with the outer plate part 512, and of the two side lips 551, 552, the radially outward side lip 551 forms a labyrinth 56 between itself and the outer plate part 512 and is formed with higher rigidity than the other lip.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sealing device for a wheel bearing assembly and a wheel bearing assembly including the same. [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 double rows of 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 an outer member and an inner member. In order to prevent water or foreign matter from the road surface from entering the annular space when the vehicle enters a waterway or travels on a rough road, the wheel bearing device must be provided with sealing devices at both open ends of the annular space. The performance of sealing devices is improving year by year, but in areas with good road conditions such as Japan, it is necessary to further improve the fuel efficiency of vehicles by reducing torque while maintaining current muddy water resistance.

[0004] Currently, the so-called Hi-Pack seal, which is composed of a slinger and a seal plate, is mainly used on the inner side of the third generation wheel bearing device and on the inner and outer sides of the first and second generation wheel bearing devices. Such Hi-Pack seals have two side lips that contribute greatly to muddy water resistance, and are structured to improve muddy water resistance compared to sealing devices with a normal structure composed of a side lip, a radial lip, and a grease lip. Recently, a structure has been considered in which the slinger is bent axially outward to form a labyrinth between the slinger and an outer member, as in the sealing device described in Patent Document 1, thereby further improving muddy water resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-158226 A Summary of the Invention [Problem to be solved by the invention]

[0006] A sealing device usually has two to three lips, and when air escapes between the lips of overlapping sealing devices, negative pressure is generated inside the device. In the sealing device, the lips stick like suction cups due to the negative pressure generated inside the lips, and a torque larger than theoretically calculated may be generated. In the above-mentioned Hi-Pack seal (hereinafter simply called a sealing device), negative pressure between the lips is generated when the sealing device is overlapped during transportation of the sealing device or when the sealing device is assembled to a wheel bearing device. For example, in a sealing device having a magnetic encoder, a protrusion made of a rubber material may be formed on the axial inner side of the seal plate so that the magnetic encoder and the core metal do not stick to each other due to magnetic force (see FIG. 6). In that case, when the sealing devices are overlapped, the slinger sinks from the normal position by the length of the protrusion (see FIG. 7). After that, when the sealing device is assembled to the wheel bearing device and the slinger and the seal plate return to their normal positions, negative pressure is generated between the lips, which may cause an increase in torque.

[0007] Therefore, the present invention provides a sealing device for a wheel support bearing assembly that can suppress an increase in torque caused by the generation of negative pressure between the lips, and a wheel support bearing assembly including the same. [Means for solving the problem]

[0008] That is, the first invention is used for sealing an annular space formed between an outer member and an inner member of a wheel bearing device, and comprises a slinger, a magnetic encoder, and a seal plate, the slinger has an outer fitting portion fitted onto the inner member, and an outer plate portion extending radially outward from one axial end of the outer fitting portion, the magnetic encoder is fixed to the outer plate portion, the seal plate has a core bar fitted onto the outer member, and an elastic member fixed to the core bar, the core bar has an inner fitting portion fitted onto the outer member, and an outer plate portion extending radially outward from one axial end of the inner fitting portion, the magnetic encoder is fixed to the outer plate portion, a sealing device for a wheel bearing device, the sealing device having an inner plate portion extending radially inward from an end portion of the elastic member facing the other axial direction, the elastic member having a plurality of lips including two side lips, and a protrusion portion protruding from an opposite side of the inner plate portion to the other axial direction side relative to the two side lips, the radially inner side lip of the two side lips being in sliding contact with the outer plate portion, the radially outer side lip of the two side lips being in sliding contact with the outer plate portion, the radially outer side lip of the two side lips being in sliding contact with the outer plate portion, and the radially outer side lip of the two side lips being formed with higher rigidity than the other lips A labyrinth amount between the radially outer side lip and the outer plate portion of the slinger is equal to or less than an axial length of the protrusion. , as stated above. Effect of the Invention

[0009] The present invention has the following advantages.

[0010] That is, according to the first aspect of the present invention, the generation of negative pressure between the lips due to the deformation of the lips is suppressed, and therefore the increase in torque due to the generation of negative pressure between the lips can be suppressed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view showing the structure of the wheel bearing device. [Diagram 2] FIG. 2 is an enlarged view showing the sealing device according to the first embodiment. [Diagram 3] FIG. 6 is an enlarged view showing a sealing device according to a second embodiment. [Figure 4] FIG. 6 is an enlarged view showing a sealing device according to a second embodiment. [Diagram 5] FIG. 11 is an enlarged view showing a sealing device according to a third embodiment. [Figure 6]FIG. [Figure 7] FIG. 1 shows a conventional sealing device superimposed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] First, a description will be given of a wheel support bearing device 1 according to the present invention. Fig. 1 is a cross-sectional view showing the overall structure of the wheel support bearing device 1.

[0013] The wheel bearing device 1 supports a wheel so as to be freely rotatable. The wheel bearing device 1 includes an outer member 2, an inner member 3, and a rolling member 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. The direction perpendicular to the rotation axis A is referred to as the "radial inner side," and the direction away from the rotation axis A is referred to as the "radial outer side." Furthermore, the "axial direction" refers to the direction along the rotation axis A of the inner member 3.

[0014] The outer member 2 constitutes the outer ring portion of the rolling bearing structure. A fitting surface 2a is formed on the inner circumference at the inner end of the outer member 2. A fitting surface 2b is formed on the outer circumference at the outer end of the outer member 2. Furthermore, two outer raceway surfaces 2c and 2d are formed on the inner circumference 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.

[0015] The inner member 3 constitutes the inner ring portion of the rolling bearing structure. The inner member 3 is composed of a hub ring 31 and an inner ring 32.

[0016] The hub wheel 31 is provided inside the outer member 2. A small diameter step 3a is formed on the outer circumference of the inner end of the hub wheel 31 up to the axial center. The small diameter step 3a refers to the portion where the outer diameter of the hub wheel 31 is reduced, and its outer circumference is cylindrical with the rotation axis A as the center. The hub wheel 31 is also formed with 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 circumference of the hub wheel 31 at the axial center. In addition, the hub wheel 31 is formed with a wheel mounting flange 3e that spreads outward in the radial direction. The wheel mounting flange 3e is provided with a plurality of bolt holes 3f centered on the rotation axis A, and a hub bolt 33 is press-fitted into each bolt hole 3f.

[0017] 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.

[0018] The rolling members 4 constitute the rolling portion 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.

[0019] The rolling elements 41 are arranged in a circle at equal intervals, each in a cage 42. The rolling elements 41 constituting the inner 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 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 wheel 31).

[0020] The cage 42 is a ring-shaped body with equally spaced pockets for accommodating the rolling elements 41. The cage 42 has spherical walls extending between adjacent rolling elements 41, and holds one rolling element 41 by sandwiching it between the two spherical walls.

[0021] In addition, the wheel bearing device 1 includes an inner side sealing device 5 and an outer side sealing device 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 sealing device 5 includes a slinger 51, a magnetic encoder 52, and a seal plate 53. The sealing device 6 includes a core metal 61 and an elastic member 62. Note that there are various specifications for the sealing device 6, and it is not limited to the specifications disclosed in this specification.

[0022] Next, the sealing device 5 will be described in detail with reference to Fig. 2. In the following description, the direction away from the annular space S along the rotation axis A is referred to as the "axially outer side", and the direction approaching the annular space S along the rotation axis A is referred to as the "axially inner side". The "axially outer side end" is an example of the "axially one side end". The "axially inner side end" is an example of the "axially other side end".

[0023] 2 is an enlarged view showing the sealing device 5. The slinger 51 is made of, for example, a steel plate and is a ring having a predetermined cross section. The slinger 51 is formed with an outer fitting portion 511 that is fitted onto the fitting surface 3g of the inner member 3. The slinger 51 is also formed with an outer plate portion 512 that extends radially outward from the axially outer end of the outer fitting portion 511.

[0024] The magnetic encoder 52 is fixed to the axially outer side of the outer plate portion 512 so as to cover the tip of the outer plate portion 512. The magnetic encoder 52 is an elastic member having magnetic poles (north and south poles) arranged in the circumferential direction.

[0025] The seal plate 53 has a core metal 54 and an elastic member 55. The core metal 54 is made of, for example, a steel plate, and is a ring having a predetermined cross section. The core metal 54 is formed with an inner fitting portion 541 that is fitted into the fitting surface 2a of the outer member 2. The core metal 54 is also formed with an inner plate portion 542 that extends radially inward from an axially inner end of the inner fitting portion 541. The elastic member 55 is made of, for example, synthetic rubber, and is fixed to the inner fitting portion 541 and the inner plate portion 542.

[0026] The elastic member 55 is formed with a plurality of lips including two side lips 551 and 552. Of the two side lips 551 and 552, the side lip 551 is disposed on the radially outer side, and the side lip 522 (hereinafter referred to as the intermediate lip 552) is disposed on the radially inner side. The side lip 551 faces the outer plate portion 512 with a gap therebetween. The intermediate lip 552 has a tip that is in sliding contact with the opposing outer plate portion 512. Furthermore, the elastic member 55 is formed with one grease lip 553, and a tip of the grease lip 553 is in sliding contact with or close to the opposing outer fitting portion 511.

[0027] The elastic member 55 is formed with a protrusion 554 that protrudes axially inward from the opposite side of the inner plate portion 542 relative to the side lip 551 and the intermediate lip 552. The elastic member 55 covers a surface opposite the inner plate portion 542 relative to the side lip 551 and the intermediate lip 552, and is formed with the protrusion 554 at its radially outer end. The elastic member 55 is configured such that, when the sealing devices 5 are overlapped, the protrusion 554 of the upper sealing device 5 comes into contact with the magnetic encoder 52 of the lower sealing device 5 in the adjacent upper and lower sealing devices 5.

[0028] Next, the features and effects of the sealing device 5 of the first embodiment will be described with reference to FIG.

[0029] As shown in FIG. 2, the side lip 551 is formed to be thicker than the intermediate lip 552 and the grease lip 553, and is formed to be more rigid than the intermediate lip 552 and the grease lip 553. For example, the thickness of the side lip 551 is set to be twice or more the thickness of the intermediate lip 552. In addition, the side lip 551 is formed such that its tip surface 551a is substantially parallel to the outer plate portion 512, and the tip surface 551a and the outer plate portion 512 are in surface contact with each other. In addition, the side lip 551 is preferably formed to extend substantially parallel to the axial direction in order to suppress deformation of the side lip 551 when it comes into contact with the outer plate portion 512. In addition, in order to form the side lip 551 with high rigidity, an elastic member made of a material having higher rigidity than that of a conventional sealing device may be used.

[0030] The side lip 551 forms a labyrinth 56 between its tip and the outer plate portion 512. The side lip 551 functions as a labyrinth slip and prevents the intrusion of foreign matter such as muddy water before the intermediate lip 552. If the intermediate lip 552 is made a labyrinth slip instead of the side lip 551, the labyrinth slip will prevent the intrusion of foreign matter after the side lip 551. However, it is considered that the effect of the labyrinth slip in preventing the intrusion of foreign matter that has intruded between the lips is small. Therefore, it is considered that the labyrinth slip for the side lip 551 provides a greater muddy water resistance due to the labyrinth 56 than the intermediate lip 552 is made a labyrinth slip.

[0031] The side lip 551 is formed so that the gap dimension between the side lip 551 and the outer plate portion 512 is shorter than the axial length of the protrusion 554 (the length by which the protrusion 554 protrudes). As a result, when the sealing devices 5 are overlapped, the tip of the side lip 551 comes into contact with the outer plate portion 512, and supports the slinger 51 which is about to sink. As a result, in the adjacent upper and lower sealing devices 5 and 5, the sinking of the slinger 51 is stopped before the core metal 54 of the upper sealing device 5 and the elastic member 55 of the lower sealing device 5 come into contact with each other, so that the amount of sinking of the slinger 51 can be made smaller than that of the conventional sealing devices.

[0032] In this way, in the sealing device 5 of the first embodiment, when the sealing devices 5 are stacked and the slinger 51 sinks, the tip of the side lip 551 comes into contact with the outer plate portion 512. The side lip 551 functions to prevent the slinger 51 from sinking any further, thereby suppressing deformation of the lip. Therefore, it is possible to suppress an increase in torque due to the generation of negative pressure between the lips. In addition, by making the side lip 551 a labyrinth lip, a specification is achieved in which torque is suppressed.

[0033] Next, features and effects of the sealing device 5 according to the second embodiment will be described. Figures 3 and 4 are enlarged views showing the sealing device 5 according to the second embodiment. Here, only the parts that are different from the sealing device 5 according to the first embodiment will be described.

[0034] As shown in FIG. 3, the outer plate portion 512 is bent inward in the axial direction to form a complicated labyrinth 56 between the elastic member 55 and the outer plate portion 512. The outer plate portion 512 forms a first bent portion 512a in which the outer plate portion 512 extending radially outward from the axially outer end of the outer fitting portion 511 is bent inward in the axial direction. The outer plate portion 512 also forms a second bent portion 512b in which the outer plate portion 512 is bent radially outward from the axially inner end of the first bent portion 512a. The outer plate portion 512 has a magnetic encoder 52 fixed to the first bent portion 512a and the second bent portion 512b so as to cover the tip of the second bent portion 512b. The labyrinth 56 is formed between the tip of the side lip 551 and the second bent portion 512b, and between the inner periphery of the elastic member 55 fixed to the inner fitting portion 541 and the outer periphery of the magnetic encoder 52.

[0035] 4, the outer plate portion 512 has a third bent portion 512c formed by bending a radially outer end portion thereof axially inward. The magnetic encoder 52 is fixed to the outer plate portion 512 so as to cover the outer periphery of the third bent portion 512c. The labyrinth 56 is formed between the tip of the side lip 551 and the outer plate portion 512, and between the inner periphery of the elastic member 55 fixed to the inner fitting portion 541 and the outer periphery of the magnetic encoder 52.

[0036] In this way, in the sealing device 5 according to the second embodiment, the labyrinth 56 is made complex. Therefore, it is possible to suppress an increase in torque while ensuring the same muddy water resistance as the conventional sealing device.

[0037] Next, features and effects of the sealing device 5 according to the third embodiment will be described. Fig. 5 is a diagram showing the sealing device 5 according to the third embodiment. Again, only the parts that are different from the sealing device 5 according to the first embodiment will be described.

[0038] The outer plate portion 512 forms a labyrinth 56 between itself and the outer member 2 by bending its radially outer end outward in the axial direction. The outer plate portion 512 forms a fourth bent portion 512d by bending its radially outer end outward in the axial direction. The magnetic encoder 52 is fixed to the outer plate portion 512 so as to cover the tip of the fourth bent portion 512d. The labyrinth 56 is formed between the tip of the side lip 551 and the outer plate portion 512, between the outer periphery of the fourth bent portion 512d and the inner periphery of the outer member 2, and between the radially outer end of the magnetic encoder 52 and the inner periphery of the outer member 2. The position where the labyrinth 56 is formed is not limited to between itself and the outer member 2, and may be between itself and other peripheral parts.

[0039] In this way, in the sealing device 5 according to the third embodiment, the labyrinth 56 is made complex. Therefore, it is possible to suppress an increase in torque while ensuring the same muddy water resistance as the conventional sealing device.

[0040] Further, it is also conceivable that the subject of the invention may change from the sealing device 5 to the wheel bearing device 1 including the sealing device 5.

[0041] That is, the generation of negative pressure between the lips due to the deformation of the lips is suppressed in the wheel bearing device 1. Therefore, it is possible to suppress an increase in torque due to the generation of negative pressure between the lips.

[0042] The wheel bearing device 1 in the present application is configured as a wheel bearing device 1 of a third generation structure in which the inner raceway surface 3d is formed directly on the outer periphery of the hub wheel 31, but is not limited to this and may be a second generation structure in which a pair of inner rings are press-fitted and fixed to the hub wheel, or a first generation structure in which a wheel bearing consisting of a double row angular contact ball bearing or a double row tapered roller bearing is fitted between the hub wheel and a knuckle that constitutes a suspension. In the case of a wheel bearing device of the first or second generation structure, the sealing device 5 according to the above embodiment may be adopted not only on the inner side but also on the outer side.

[0043] Finally, the invention in this application is not limited in any way to the respective embodiments, which are merely illustrative, and it goes without saying that the invention can be embodied in various forms without departing from the gist of the 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]

[0044] 1 Wheel bearing device 2 Outer member 3 Inner members 5 Sealing device 51 Slinger 52 Magnetic Encoder 53 Seal plate 54 Core wire 55 Elastic member 56 Labyrinth 511 External fitting part 512 Outer panel part 541 Inner fitting part 542 Inner plate part 554 Protrusion 551 Side Lip 552 Middle lip (side lip) 553 Grease Lip S Annular space

Claims

1. The present invention is used to seal an annular space formed between an outer member and an inner member of a wheel bearing device, A slinger, a magnetic encoder, and a seal plate are provided. The slinger has an outer fitting portion that is fitted onto the inner member, and an outer plate portion that extends radially outward from one axial end of the outer fitting portion, The magnetic encoder is fixed to the outer plate portion, the sealing plate has a core metal fitted to the outer member and an elastic member fixed to the core metal, the core metal has an inner fitting portion that is fitted into the outer member, and an inner plate portion that extends radially inward from another axial end portion of the inner fitting portion, The elastic member is provided with a plurality of lips including two side lips, and a protrusion protruding from an opposite side of the inner plate portion relative to the two side lips toward the other axial direction, The radially inner side lip of the two side lips is in sliding contact with the outer plate portion, a sealing device for a wheel bearing assembly, characterized in that the radially outer side lip of the two side lips forms a labyrinth between itself and the outer plate portion and is formed with higher rigidity than the other lip, and a labyrinth amount between the radially outer side lip and the outer plate portion of the slinger is equal to or less than the axial length of the protrusion portion.

2. 2. The sealing device according to claim 1, wherein the radially outer side lip of the two side lips is formed to have a greater wall thickness than the other lip.

3. 3. The sealing device according to claim 1, wherein the outer plate portion is bent in the other axial direction to form a labyrinth between the outer plate portion, the magnetic encoder, and the elastic member.

4. 3. The sealing device according to claim 1, wherein a labyrinth is formed between the outer plate portion and the magnetic encoder and the outer member by bending a radially outer end portion of the outer plate portion to one side in the axial direction.

5. A wheel bearing assembly comprising the sealing device according to any one of claims 1 to 4.

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