JP2022156566A - Wheel bearing device - Google Patents

Abstract

To provide a wheel bearing device including a seal member capable of suppressing the occurrence of a pressure difference between inside and outside a seal lip, suppressing a reduction of grease sealed therein, and suppressing an increase in the rotation torque while preventing the wear at the front end of the seal lip due to suction-adhesion onto a slide surface.SOLUTION: An outer side seal member 7 includes a core metal 71 fitted to an outer ring 2, and a seal body 72 consisting of an elastic body joined to the core metal 71, the seal body 72 having a seal lip 72b extending in an axial direction and having a front end slidably contacting a slide surface (a flat part 31a, a shaft peripheral face part 31b, and a circular-arc face part 31c) of an inner member. At the front end of the seal lip 72b, a plurality of protruding parts 74a is provided protruding toward the slide surface and arranged along a peripheral edge of the front end.SELECTED DRAWING: Figure 3

Description

The present invention relates to a wheel bearing device.

2. Description of the Related Art Conventionally, there has been known a wheel bearing device that rotatably supports a wheel in a vehicle suspension system such as an automobile.
The wheel bearing device, for example, has a structure in which a hub wheel (inner member) connected to a wheel is rotatably supported by an outer member via rolling elements.
Moreover, the wheel bearing device is often arranged in a space surrounded mainly by the suspension device, the tire hole of the wheel, the brake rotor, and the like, in a state of being exposed to the outside.
For this reason, in order to prevent foreign matter such as muddy water from entering the installation space of the rolling elements from the outside, the wheel bearing device has an annular space formed between the outer member and the inner member. , sealing members are provided at the opening ends of the inner side and the outer side.

By the way, FIG. 7 is a view showing an example of the outer side seal member 107 in the conventional wheel bearing device 101. As shown in this figure, the seal member 107 has a plurality of seal lips 172b, 172b, . The tips of 172b (outer axial lip 173, inner axial lip 174, and radial lip 175) are all sliding surfaces (flat surface portion 131a, shaft peripheral surface portion 131b, and arcuate surface portion 131c) of hub wheel 103, which is an inner member. ) is in contact with
Therefore, between the plurality of seal lips 172b, 172b, 172b and the sliding surface of the hub wheel 103, there is a sealed space separated by the inner axial lip 174, that is, the outer axial lip 173 and the inner axial lip 174. and a second lip space P2 isolated by the radial lip 175 and the inner axial lip 174 .

When a vehicle provided with such a wheel bearing device 101 is driven and the temperature in each of the sealed spaces rises, the air in these sealed spaces expands, passes through the seal member 107 and is discharged to the outside. may be
Specifically, the air in the first lip space P1 is pushed radially outward (in the direction of arrow B) as the volume increases, passes through the tip of the outer axial lip 173, and is discharged to the outside. be.
As the volume of the air in the second lip space P2 increases, it is pushed out to one side in the axial direction (direction of arrow C), passes through the tip of the radial lip 175, and is discharged to the outside.
In the first lip space P1 and the second lip space P2, after the air is discharged to the outside, the tip of the outer axial lip 173 and the tip of the radial lip 175 immediately come into contact with the sliding surface. As a result, it becomes a closed state again.

Then, when the operation of the vehicle is stopped after that and the temperature in each sealed space drops to around room temperature, the pressure in the first lip space P1 and the pressure in the second lip space P2 decrease, respectively. It becomes a negative pressure with respect to the atmospheric pressure.
As a result, a differential pressure is generated between the first lip space P1 and the second lip space P2, and the tip of the inner axial lip 174 is drawn radially inward (opposite to the direction of arrow B). As a result, the sliding surface (more specifically, the arc surface portion 131c) may be in a state of being sucked.

Under such circumstances, when the operation of the vehicle provided with the wheel bearing device 101 is resumed and the relative rotation between the plurality of seal lips 172b, 172b, 172b and the hub wheel 103 is repeated, the inner axial The tip of the lip 174 is significantly worn, which not only lowers the sealing performance, but also increases the torque required to rotate the hub wheel connected to the wheel, which is uneconomical.
An example of technology for solving such problems is disclosed in Patent Document 1.
That is, Patent Document 1 discloses a technique related to a sealing device (corresponding to a seal member) composed of a so-called pack seal. A space surrounded by the lip and the base, which corresponds to the first lip space P1; This is an enclosed space corresponding to the second lip space P2 (hereinafter referred to as the "inner space"). A sealing device is disclosed that can prevent this and suppress wear of the axial lip.

JP 2010-190323 A

In the sealing device disclosed in Patent Document 1, the bent extension portion of the slinger (corresponding to the sliding surface of the hub wheel (inner member)) extends radially inward at the radially outer side of the distal end portion of the axial lip. It is provided so as to extend obliquely toward the axial lip and cover the tip of the axial lip.
Therefore, when the temperature in the inner space rises and the air inside expands, the tip of the axial lip temporarily floats radially outward, but comes into contact with the bent and extended portion, and is forced inward. Since the airtightness of the space is maintained, it is possible to prevent the air in the inner space from passing through the tip of the axial lip and being discharged to the outside.
Therefore, according to the sealing device in Patent Document 1, even if the temperature in the inner space drops to near room temperature after that, the pressure in the inner space becomes a negative pressure with respect to the external atmospheric pressure. can be suppressed, and the distal end portion of the axial lip can be prevented from strongly sticking to the bent extension portion of the slinger.
The outer space communicates with the outside, and air can freely flow in and out according to the atmospheric pressure in the outer space. It does not become a factor to generate differential pressure between them.

However, in the sealing device disclosed in Patent Document 1, when the tip portion of the axial lip floats radially outward, the grease in the inner space is pushed radially outward together with the internal air, causing the above bending and extension. It will be pushed near the base of the part.
As a result, after that, even if the temperature in the inner space drops to around room temperature and the tip of the axial lip returns to its normal position, the grease pushed into the vicinity of the base of the bent extension portion will be removed again. It is difficult to get back into the inner space.
Therefore, the amount of grease in the inner space gradually decreases with the passage of time, accelerating the wear of the tip of the axial lip and increasing the torque when rotating the hub wheel connected to the wheel. can be a factor.
In addition, as described above, the bent extension portion of the slinger extends radially inwardly so as to cover the tip portion of the axial lip on the radially outer side of the tip portion of the axial lip. As a result, when the slinger is assembled by moving it in the axial direction in the process of assembling the sealing device, the distal end portion of the axial lip and the bent extension portion are likely to interfere with each other, making assembly work difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the present situation as described above, and is capable of suppressing the differential pressure generated between the inside and outside of the seal lip and suppressing the reduction of the enclosed grease. It is an object of the present invention to provide a wheel bearing device equipped with a seal member capable of preventing the tip of the seal lip from being worn by being attracted to the sliding surface and suppressing an increase in rotational torque. and

The problems to be solved by the present invention are as described above, and the means for solving the problems will now be described.

That is, a wheel bearing device according to the present invention comprises an outer member having a double-row outer raceway surface on the inner circumference, a hub ring having a small diameter step portion extending axially on the outer circumference, and the small diameter step of the hub ring. an inner member comprising at least one inner ring press-fitted into a part and having on its outer periphery a double-row inner raceway surface facing the double-row outer raceway surface; and raceways of each of the outer member and the inner member A wheel bearing device comprising: a double-row rolling element that is rollably accommodated between surfaces; and a seal member that closes an open end of an annular space formed by the outer member and the inner member, The member includes a core metal fitted to the outer member, and a sealing body made of an elastic body joined to the core metal. It has a seal lip in slidable contact with a sliding surface of the member, and a plurality of seals projecting toward the sliding surface and arranged along the periphery of the tip end of the seal lip. is provided with a protrusion.

As effects of the present invention, the following effects are obtained.
That is, according to the wheel bearing device of the present invention, it is possible to suppress the differential pressure generated between the inside and the outside of the seal lip, and to suppress the reduction of the enclosed grease. It is possible to realize a seal member that can prevent the portion from being worn by being attracted to the sliding surface and can suppress an increase in rotational torque.

1 is a cross-sectional view showing the overall configuration of a wheel bearing device according to the present invention; 2A is a cross-sectional side view of the outer seal member according to the first embodiment of the present invention, and FIG. 1 is a front view looking in a direction; FIG. In the first embodiment of the present invention, it is an enlarged view of the portion indicated by the area A1 in FIG. 1, (a) is an enlarged cross-sectional view seen in the direction of the arrow Y1 in FIG. ) is an enlarged sectional view seen in the direction of arrow Y2 in FIG. FIG. 3(a) is an enlarged cross-sectional view of the portion indicated by area A2 in FIG. FIG. 9 is an enlarged cross-sectional view showing the shape of the tip of an inner axial lip in another embodiment; FIG. 10 is a diagram for explaining the wheel bearing device according to the second embodiment of the present invention, and is a front view showing the overall configuration of the outer side seal member. FIG. 10 is a diagram for explaining wheel bearing devices according to third to fifth embodiments of the present invention, where (a) is an enlarged cross section of a portion indicated by area A1 in FIG. 1 in the third embodiment; It is a figure, (b) is an enlarged cross-sectional view of the portion indicated by the area A3 in FIG. 1 in the fourth embodiment, (c) is indicated by the area A3 in FIG. 1 in the fifth embodiment It is an enlarged cross-sectional view of a part. FIG. 2 is an enlarged cross-sectional view of a portion indicated by area A1 in FIG. 1 in a conventional wheel bearing device;

Next, one embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG.
For the sake of convenience, the present specification will be described based on the inner side and the outer side defined by the directions of the arrows in FIG.
Here, the "inner side" means the direction toward the inner side of the vehicle body with respect to the wheel bearing device 1 attached to the vehicle body of an automobile or the like.
Further, the "outer side" means the side opposite to the inner side of the wheel bearing device 1 in a state of being attached to the vehicle body of an automobile, that is, the wheel bearing device 1 rotatably supports the bearing device. means the direction of the wheel side that is set.

Further, in this specification, the direction parallel to the rotation axis G (see FIG. 1) of the wheel bearing device 1 is referred to as the "axial direction," and the direction perpendicular to the rotation axis G of the wheel bearing device 1 is referred to as the "diameter direction." "direction", and the direction along an arc centered on the rotation axis G of the wheel bearing device 1 is defined as "circumferential direction".

[Overall Configuration of Wheel Bearing Device 1 (First Embodiment)]
First, the overall configuration of a wheel bearing device 1 according to a first embodiment of the present invention will be described with reference to FIG.

A wheel bearing device 1 rotatably supports a wheel in a suspension device of a vehicle such as an automobile.
The wheel bearing device 1 mainly includes an outer ring 2 which is an example of an outer member, a hub ring 3 and an inner ring 4, and double-row (two-row in this embodiment) ball rows 5 and 5 which are rolling elements. and an inner side seal member 6 and an outer side seal member 7 which are examples of seal members.

The outer ring 2 supports the hub ring 3 and the inner ring 4 .
The outer ring 2 is formed of a substantially hollow cylindrical member, and is provided with an inner opening 2a at its inner end, into which the inner seal member 6 can be fitted, and at its outer end. , an outer-side opening 2b into which the outer-side seal member 7 can be fitted.

Further, on the inner circumference of the outer ring 2, outer raceway surfaces 2c, 2c are provided in circumferentially annular double rows (two rows in this embodiment) coaxially and spaced apart in the axial direction. A flange (not shown) that can be attached to the knuckle of the suspension is integrally provided on the outer periphery of the suspension.

The hub wheel 3 is a member that constitutes an inner member together with the inner ring 4, and rotatably supports a vehicle wheel (not shown).
The hub wheel 3 is made of a substantially solid columnar member, and has a small-diameter stepped portion 3a extending in the axial direction on the outer periphery on the inner side thereof.
A wheel mounting flange 3b to which the wheel can be mounted is integrally provided at the outer end of the hub wheel 3 so as to expand in a circular arc shape when viewed in a radial cross section.

A plurality of hub bolts 3c, 3c, .
An inner raceway surface 3d annular in the circumferential direction is provided on the outer circumference of the hub wheel 3 so as to face the outer raceway surface 2c.

An inner ring 4 is press-fitted into the small-diameter stepped portion 3 a of the hub wheel 3 .
The inner ring 4 is a member that constitutes an inner member together with the hub wheel 3, and is made of a substantially hollow cylindrical member. It is provided so as to face the raceway surface 2c.

The inner ring 4 is fixed to the hub wheel 3 by plastically deforming (caulking) the inner side end portion of the hub wheel 3 radially outward.
The method of fixing the inner ring 4 to the hub wheel 3 is not limited to this embodiment. may be

In this way, in the inner member composed of the hub wheel 3 and the inner ring 4, the inner raceway surface 4a provided on the inner ring 4 is arranged at the inner end thereof, and the inner raceway surface 4a is arranged at the outer end thereof. , the inner raceway surface 3d provided on the hub wheel 3 is arranged, and these double-row (two-row in this embodiment) inner raceway surfaces 3d and 4a are arranged on the two-row outer raceway surface provided on the outer ring 2 described above. The surfaces 2c, 2c are arranged so as to face each other.

The two rows of ball rows 5 and 5 rotatably support an inner member composed of the hub wheel 3 and the inner ring 4 relative to the outer ring 2 .
The ball row 5 in each row is composed of a plurality of balls 5a, 5a .

These two rows of ball rows 5, 5 are composed of two rows of outer raceway surfaces 2c, 2c provided at the inner-side and outer-side ends of the outer ring 2, respectively, and inner members (hub ring 3 and inner ring 4). are rotatably accommodated in two rows of installation spaces Q1 and Q1 formed between the two rows of inner raceway surfaces 3d and 4a respectively provided at the ends of the inner side and the outer side of the .

Thus, the wheel bearing device 1 in this embodiment is configured as a double-row angular contact ball bearing including the outer ring 2, hub ring 3, inner ring 4, and two rows of ball rows 5.5.
The configuration of the wheel bearing device 1 is not limited to that of the present embodiment. good.

The inner side seal member 6 closes the inner side open end of the annular space Q2 formed by the outer ring 2 and the inner members (the hub wheel 3 and the inner ring 4).
The inner side seal member 6 includes a substantially cylindrical seal plate 6a, a substantially cylindrical slinger 6b, and the like.

The seal plate 6a is made of, for example, a ferritic stainless steel plate (JIS SUS430 series, etc.), an austenitic stainless steel plate (JIS SUS304 series, etc.), or a dustproof cold-rolled steel plate (JIS SPCC series, etc.). It is formed by pressing an annular steel plate made of, for example.
The seal plate 6a is formed to be bent in an L-shape when viewed in the circumferential direction, and a plurality of seal lips 6a1, 6a1, 6a1 made of synthetic rubber, for example, are vulcanized and bonded to the inner side of the seal plate 6a. .

The seal lip 6a1 is made of, for example, NBR (acrylonitrile-butadiene rubber), HNBR (hydrogenated acrylonitrile-butadiene rubber) excellent in heat resistance, EPDM (ethylene propylene rubber), ACM ( polyacrylic rubber), FKM (fluororubber), or an elastic body made of synthetic rubber such as silicone rubber.

On the other hand, similarly to the seal plate 6a, the slinger 6b is also made of, for example, a ferritic stainless steel plate (JIS SUS430 series, etc.), an austenitic stainless steel plate (JIS SUS304 series, etc.), or a cold-rolled steel plate dust-proofed. It is formed by pressing an annular steel plate made of (JIS standard SPCC, etc.) or the like.
The slinger 6b is made of a steel plate or the like that is annular and bent into an L-shape when viewed in the circumferential direction.

The magnetic encoder 6b1 is made of an elastomer such as rubber mixed with magnetic powder such as ferrite, so that the magnetic poles N and S are magnetized alternately and at equal intervals in the circumferential direction to change the magnetic characteristics of the wheel. is configured as a rotary encoder for detecting the rotational speed of the

The seal plate 6a is fitted to the inner side opening 2a of the outer ring 2 while being coaxial with the outer ring 2 and with the plurality of seal lips 6a1, 6a1, 6a1 directed toward the slinger 6b.
The slinger 6b is fitted on the outer circumference of the inner ring 4 coaxially with the inner ring 4 and on the inner side of the seal plate 6a so as to face the seal plate 6a.
As a result, the inner side seal member 6 is configured as a pack seal consisting of the seal plate 6a and the slinger 6b.

The outer side seal member 7 is positioned at an outer side opening end (more specifically, an outer side opening 2b of the outer ring 2) in an annular space Q2 formed by the outer ring 2 and the inner members (the hub wheel 3 and the inner ring 4). is blocked.
The details of the configuration of the outer side seal member 7 will be described later.

As described above, the wheel bearing device 1 of this embodiment has a third-generation structure in which the inner raceway surface 3d on which the outer ball train 5 can roll is directly formed on the outer periphery of the hub wheel 3. Although it is constructed as a bearing device for a wheel, it is not limited to this. The inner raceway surfaces on which the rows can roll can also be configured as second-generation wheel bearing arrangements directly formed.

[Configuration of Outer Side Seal Member 7]
Next, the configuration of the outer side seal member 7 will be described in detail with reference to FIGS. 2 to 4. FIG.
As shown in FIG. 3( a ), the outer side seal member 7 includes a core metal 71 fitted to the outer ring 2 , and a sealing body 72 made of an elastic body joined to the core metal 71 and the like.

The core metal 71 is, for example, a ferritic stainless steel plate (JIS SUS430 series, etc.), an austenitic stainless steel plate (JIS SUS304 series, etc.), or a dust-proof cold-rolled steel plate (JIS SPCC series, etc.). It is formed by pressing an annular steel plate made of, for example.
The core metal 71 is mainly composed of a cylindrical portion 71a, a curved portion 71b, a disk portion 71c, and the like.

The cylindrical portion 71 a is formed in a hollow cylindrical shape extending in the axial direction, and has an outer diameter set substantially equal to the inner diameter of the outer opening 2 b of the outer ring 2 .
The curved portion 71b is formed in an annular shape that protrudes toward the outer side (see FIG. 1) in the axial direction when viewed in the circumferential direction. are set consecutively.
Further, the disc portion 71c is formed in an upright disc shape, and is continuously provided radially inward from the end portion of the curved portion 71b.

On the other hand, a seal member 72 is joined to the outer side surface of the cored bar 71 so as to wrap around toward the outer peripheral surface of the cylindrical portion 71a, and the outer side seal member 7 has a so-called half-metal structure. there is

The outer-side seal member 7 is the outer-side end of the outer-side opening 2b of the outer ring 2 (that is, the annular space Q2 (see FIG. 1) described above) via the cylindrical portion 71a of the core metal 71. and is fitted to the inner circumference of the outer ring 2).
As a result, the airtightness of the annular space Q<b>2 of the wheel bearing device 1 is improved, and the inside of the bearing can be protected by the outer side seal member 7 .

The seal body 72 is made of, for example, NBR (acrylonitrile-butadiene rubber), HNBR (hydrogenated acrylonitrile-butadiene rubber) with excellent heat resistance, EPDM (ethylene propylene rubber), ACM (polyacrylic rubber) with excellent heat resistance and chemical resistance. rubber), FKM (fluororubber), or synthetic rubber such as silicone rubber, and is integrally joined to the core metal 71 by vulcanization adhesion.
The seal body 72 includes a base portion 72a covering the outer side surface of the cored bar 71, and extending in the axial direction from the base portion 72a. It has a plurality of seal lips 72b, 72b, 72b that slidably come into contact with a plane portion 31a, an axial peripheral surface portion 31b, and an arc surface portion 31c, which will be described later.

Each of the seal lips 72b, 72b, 72b is formed in an annular shape and is composed of an outer axial lip 73, an inner axial lip 74, and a radial lip 75 which are coaxially arranged.

Here, the outer axial lip 73 is formed so as to incline radially outward and extend in one direction in the axial direction (in this embodiment, toward the outer side) in a circumferential cross-sectional view.
In addition, the inner axial lip 74 is positioned radially inward of the outer axial lip 73 and is formed so as to extend in one axial direction (outer side direction) while being inclined radially outward in a circumferential cross-sectional view. ing.
Further, the radial lip 75 is positioned radially inward of the inner axial lip 74, and is inclined radially inward in a circumferential cross-sectional view to the other axial side (inner side in FIG. 1 in this embodiment). ) is formed to extend in the direction of ).

The outer axial lip 73 , the inner axial lip 74 , and the radial lip 75 are in slidable contact with the stepped portion 31 of the hub wheel 3 at their tip portions.

Here, the stepped portion 31 refers to a portion provided to protrude toward the inner side at the base end portion of the wheel mounting flange 3b of the hub wheel 3 .
Specifically, the stepped portion 31 is a plane portion 31a formed of a plane perpendicular to the rotation axis G (see FIG. 1), is positioned radially inside the plane portion 31a, and is coaxial with the rotation axis G. It is composed of an extending axial peripheral surface portion 31b and an arcuate surface portion 31c smoothly connecting the planar portion 31a and the axial peripheral surface portion 31b.
The outer peripheral surface portion 31d of the stepped portion 31 is inclined with a predetermined curvature, and smoothly connects from the outer edge of the flat portion 31a to the seat surface 31e of the hub bolt 3c (see FIG. 1).

The tip portion of the outer axial lip 73 is in contact with the flat surface portion 31a of the stepped portion 31 through the oil film of grease Z, which is a lubricant, and the tip portion of the inner axial lip 74 is in contact with the oil film through the oil film. , and the arcuate surface portion 31c of the stepped portion 31, and the tip portion of the radial lip 75 is in contact with the axial peripheral surface portion 31b of the stepped portion 31 via the oil film.
As a result, between the plurality of seal lips 72b, 72b, 72b and the stepped portion 31 of the hub wheel 3, there is a sealed space separated by the inner axial lip 74, that is, the outer axial lip 73 and the inner axial lip 74. and a second lip space P2 isolated by the radial lip 75 and the inner axial lip 74 are formed.

By the way, as shown in FIG. 2(a), in this embodiment, a plurality of protrusions 74a, 74a, . . . The projections 74a, 74a, . . . are arranged at predetermined intervals along the circumferential direction.
Each projecting portion 74a is formed to protrude toward an arcuate surface portion 31c (also see FIG. 3(a)) as a sliding surface provided on the stepped portion 31 (see FIG. 3(a)). It is

Specifically, as shown in FIG. 2B, each protrusion 74a is formed as an arcuate tongue extending along the tip of the inner axial lip 74 when viewed in the axial direction. The radially inner corners 74a1 at both ends reduce the contact area between the protrusion 74a and the arcuate surface 31c (see FIG. 3), thereby reducing the sliding resistance when the outer side seal member 7 rotates. For the purpose of this, it is formed so as to have a roundness with a radius R of 3 mm or less (0 mm<R≦3 mm).

Further, as shown in FIG. 4(a), both corners 74a2 on the arc surface 31c side of each protrusion 74a in a circumferential cross-sectional view are similar to the corners 74a1, and when the outer seal member 7 rotates, It is formed to have roundness for the purpose of reducing the sliding resistance of.
As another embodiment of each protrusion 74a, for example, as shown in FIG. may be formed in a substantially semicircular shape in a cross-sectional view.

Then, as shown in FIG. 4A, the thickness from the side surface on the arc surface portion 31c side to the side surface opposite to the arc surface portion 31c side in each projection portion 74a, that is, the height dimension H of each projection portion 74a is 0.6 mm or less (0 mm <H≦0.6 mm).

A plurality of protrusions 74a having such a shape are arranged at equal intervals with a predetermined gap along the periphery of the tip of the inner axial lip 74, as shown in FIG. 2(b). be.
A virtual pitch circle S1 passing through the center position (center of gravity) of each protrusion 74a in the circumferential direction and centered on the rotation axis G (see FIG. 1) is defined as a virtual pitch circle S1. When a virtual circle coaxial with the virtual pitch circle S1 that is inscribed in and has a radial dimension of r is defined as a virtual inscribed circle S2, the length T of the arc on the virtual pitch circle S1 at each protrusion 74a is set to be less than or equal to the length of the semicircle of the imaginary inscribed circle S2 (0<T≦πr).
In addition, in the gap between the adjacent projections 74a, 74a, the separation dimension L on the imaginary pitch circle S1 is also equal to or less than the length of the semicircle of the imaginary inscribed circle S2 (0< L≦πr).

Regarding the relationship between the length dimension T and the separation dimension L, the gap dimension L is smaller than the length dimension T (T>L) in order to suppress the deterioration of the muddy water resistance of the inner axial lip 74 as much as possible. It is desirable to be set so that
In addition, the smaller the number of projections 74a, the higher the muddy water resistance of the inner axial lip 74 can be maintained, and the above length dimension T and separation dimension L are set in consideration of this viewpoint. .

As described above, in the present embodiment, since a plurality of protrusions 74a, 74a, . . . Between 74a, the tip of the inner axial lip 74 is out of contact with the sliding surface (arc surface portion 31c) of the hub wheel 3, which is the inner member, and a plurality of gaps D.D.・ will occur.

As a result, the first lip space P1 and the second lip space P2 separated by the inner axial lip 74 are communicated through the gap D, and the pressure in the first lip space P1 and the second lip space The pressure inside P2 is always maintained in a uniform state, and the differential pressure generated between the first lip space P1 and the second lip space P2 can be suppressed.

Also, by having a plurality of gaps D.D. . Since the contact area is reduced compared to the case where the entire tip portion of the inner axial lip 74 is in contact with the arc surface portion 31c, the rotational torque of the wheel bearing device 1 can be reduced.

Furthermore, even if the grease Z is unexpectedly pushed out radially outward through the tip of the inner axial lip 74 due to, for example, centrifugal force, the extruded grease Z is forced out of the plurality of gaps D due to the influence of gravity. · D .
Therefore, the amount of grease Z at the tip of the inner axial lip 74 does not gradually decrease with the passage of time. can be done.

On the other hand, the presence of such a plurality of gaps D.D. . . may reduce the muddy water resistance of the inner axial lip 74. The tip portion is in contact with the sliding surface (arc surface portion 31c) of the hub wheel 3, which is the inner member, through a plurality of protrusions 74a, 74a, and is provided with at least the protrusion 74a. In the region, the first lip space P1 and the second lip space P2 are maintained in a closed state, so that the deterioration of the muddy water resistance can be suppressed as much as possible.

In this embodiment, it is sealed in the gap between the tip of each seal lip 72b and the sliding surface (flat portion 31a, axial peripheral surface portion 31b, and arc surface portion 31c) of the hub wheel 3, which is an inner member. The grease Z used has a mixed consistency range of 175 or more and 385 or less.

Generally, the mixed consistency range of the grease enclosed in the seal member is often set to 400 or less. The range is lower than that of general grease, and grease Z with high viscosity is used.

Therefore, for example, even if the relative rotation between the outer seal member 7 and the hub wheel 3 is repeated due to driving of a vehicle provided with the wheel bearing device 1, the grease Z is prevented from being discharged to the radially outer side of the inner axial lip 74, i.e., to the first lip space P1 side, through the gap D, and at least temporarily remains so as to close the gap D. .
As a result, the grease Z can maintain the sealed state of the second lip space P2 in the clearance D, thereby more reliably suppressing deterioration of the inner axial lip 74 in resistance to muddy water.

As described above, in the wheel bearing device 1 of the present embodiment, the tip of the seal lip 72b (more specifically, the inner axial lip 74) has a sliding surface of the hub wheel 3, which is an inner member. That is, a plurality of projecting portions 74a, 74a, .
Therefore, a plurality of gaps D, D, .

Therefore, as described above, for example, when the vehicle provided with the wheel bearing device 1 is driven, the air in the first lip space P1 and the air in the second lip space P2 expand, and the air in the first lip space P1 expands. is discharged to the outside through the tip of the outer axial lip 73, and the air in the second lip space P2 is discharged to the outside through the tip of the radial lip 75. Via the gaps D, D, .

Also, the grease Z that has passed through the tip of the inner axial lip 74 and has been pushed out once can be recovered through the plurality of gaps D.D.
As a result, it is possible to prevent the tip of the inner axial lip 74 from being attached to the sliding surface (arc surface portion 31c) of the hub wheel 3 and being worn.

Furthermore, since the tip portion of the inner axial lip 74 can be prevented from being attracted to the sliding surface (arc surface portion 31c) of the hub wheel 3, an increase in rotational torque in the wheel bearing device 1 can be suppressed.

In this embodiment, a plurality of protrusions 74a, 74a, ... are provided only at the tip of the inner axial lip 74, but the present invention is not limited to this. A plurality of protrusions 74a, 74a, .

A plurality of protrusions 74a, 74a, ... are provided at the distal end portion of the outer axial lip 73, so that through a plurality of gaps D, D, ... formed by the protrusions 74a, 74a adjacent to each other. , suppresses the differential pressure generated between the external space located outside the outer axial lip 73 and the first lip space P1 located inside, and passes through the tip portion of the outer axial lip 73 to temporarily reach the outside. The extruded grease Z can be recovered again through the plurality of gaps D.D.
As a result, the tip portion of the outer axial lip 73 can be prevented from being worn by being attracted to the sliding surface of the hub wheel 3, which is the inner member, that is, the flat portion 31a.
Further, since the tip portion of the outer axial lip 73 can be prevented from being attracted to the flat portion 31a, an increase in rotational torque in the wheel bearing device 1 can be suppressed.

Alternatively, a plurality of projections 74a, 74a, . to suppress the pressure difference between the annular space Q2 (see FIG. 1) located outside the radial lip 75 and the second lip space P2 located inside the radial lip 75. The grease Z that has passed through and is once pushed out to the annular space Q2 side can be recovered again through the plurality of gaps D.D.
As a result, it is possible to prevent the tip of the radial lip 75 from being worn by being attracted to the sliding surface of the hub wheel 3, which is the inner member, that is, the shaft peripheral surface portion 31b.
Moreover, since the tip of the radial lip 75 can be prevented from being attracted to the shaft peripheral surface portion 31b, an increase in rotational torque in the wheel bearing device 1 can be suppressed.

[Configuration of Wheel Bearing Device 201 (Second Embodiment)]
Next, the configuration of the wheel bearing device 201 according to the second embodiment will be described with reference to FIGS. 1 and 5. FIG.
In FIG. 1, a wheel bearing device 201 in the second embodiment has substantially the same configuration as the wheel bearing device 1 in the first embodiment described above, but mainly includes protrusions provided on an outer seal member 207. 274a (see FIG. 5) is different from that of the wheel bearing device 1. As shown in FIG.
Therefore, in the following description, differences from the above-described wheel bearing device 1 will be mainly described, and descriptions of structures equivalent to the wheel bearing device 1 will be omitted.

As shown in FIG. 5, a plurality of protrusions 274a, 274a, .
Each projecting portion 274a is formed so as to protrude toward an arcuate surface portion 31c (also see FIG. 3(a)) as a sliding surface provided on the hub wheel 3 (see FIG. 3(a)). It is
The details of the shape of each protrusion 274a are the same as those of each protrusion 74a of the above-described wheel bearing device 1, so description thereof will be omitted.

The plurality of protrusions 274a, 274a, .
Here, the "road surface side" means the side where the road surface is located (for example, the lower side) with respect to the wheel bearing device 201 (see FIG. 1) in a state of being attached to the vehicle body of an automobile or the like. The term "anti-road surface side" means the side opposite to the road surface (for example, the upper side).

Specifically, when a virtual pitch circle S1 passing through the center position (center of gravity) of each projection 274a and having a rotation axis G (see FIG. 1) as a center is defined as a virtual pitch circle S1, a plurality of is an area on the opposite side of the road surface on the virtual pitch circle S1, and the central angle α exceeds 0° and is 180° or less on the virtual arc S1a. 274 in the circumferential direction (center of gravity).

The distal end portion of the inner axial lip 274 is in sliding contact with the circular arc surface portion 31c of the stepped portion 31 via a plurality of protrusions 274a, 274a, . . . In the area on the virtual pitch circle S1 excluding the virtual arc S1a, where the protrusions 274a, 274a, ... are not provided, the arc surface portion 31c of the stepped portion 31 is directly connected via the tip portion. Sliding contact.

With such a configuration, the tip of the inner axial 274 is brought into contact with the arcuate surface 31c of the hub wheel 3 in the region on the road surface side, where foreign matter such as muddy water is relatively likely to enter from the outside. While ensuring high muddy water resistance performance on the opposite side of the road surface, the difference between the inside and outside of the inner axial lip 274 is reduced through a plurality of gaps D D (see FIG. 3B). By suppressing the pressure, it is possible to suppress wear of the tip portion of the inner axial lip 274 and an increase in rotational torque in the wheel bearing device 201 .

[Configuration of Wheel Bearing Device 301 (Third Embodiment)]
Next, the configuration of the wheel bearing device 301 according to the third embodiment will be described with reference to FIGS. 1 and 6(a).
In FIG. 1, a wheel bearing device 301 in the third embodiment has substantially the same configuration as the wheel bearing device 1 in the first embodiment described above, while the configuration of the outer seal member 307 is mainly different from that of the dam. It differs from the wheel bearing device 1 in that it is of a type provided with a portion 376 (see FIG. 6(a)).
Therefore, in the following description, differences from the above-described wheel bearing device 1 will be mainly described, and descriptions of structures equivalent to the wheel bearing device 1 will be omitted.

As shown in FIG. 6A, the outer side seal member 307 has a metal core 371 fitted to the outer ring 2, a seal body 372 made of an elastic body joined to the metal core 371, and the like.

The core metal 371 is mainly composed of a cylindrical portion 371a, a bent portion 371b, a disk portion 371c, a collar portion 371d, and the like.
The material of the cored bar 371 is the same as that of the cored bar 71 of the outer-side seal member 7 in the wheel bearing device 1 described above, and thus the description thereof is omitted.

The cylindrical portion 371a extends from the end portion on the outer side (see FIG. 1) of the outer ring 2 toward the inner side (also see FIG. 1). It is set approximately equal to the inner diameter.
The bent portion 371b is once bent radially inward from the inner side end portion of the cylindrical portion 371a and extends toward the outer side to an axially intermediate portion of the cylindrical portion 371a.
Further, the disk portion 371c extends radially inward to the vicinity of the outer periphery of the hub wheel 3 from the outer end portion of the bent portion 371b.

The collar portion 371d extends radially outward from the outer end portion of the cylindrical portion 371a.
Note that the radially outer end of the flange 371d is located radially outside the outer peripheral surface of the outer-side end of the outer ring 2, and the radially outer end of the flange 371d has the above-described An outer edge portion 371e extending toward the inner side is provided while having a predetermined gap with respect to the outer peripheral surface.

On the other hand, the seal body 372 has a plurality of seal lips 372b, 372b, 372b provided on the disk portion 371c of the cored bar 371, a dam portion 376 provided on the outer edge portion 371e of the cored bar 371, and the like. The seal lips 372 b , 372 b , 372 b are composed of an outer axial lip 373 , an inner axial lip 374 and a radial lip 375 .
The material of the seal body 372 is the same as that of the seal body 72 of the outer-side seal member 7 in the wheel bearing device 1 described above, so description thereof will be omitted.

The outer axial lip 373 is formed to extend radially outward on the outer side.
The inner axial lip 374 is provided radially inward with respect to the outer axial lip 373 and is formed to extend toward the outer side.
Further, the radial lip 375 is provided radially inward with respect to the inner axial lip 374 and is formed to extend radially inward on the inner side.

These outer axial lip 373, inner axial lip 374, and radial lip 375 are arranged coaxially with each other, and are arranged on the sliding surfaces (flat portion 31a, shaft peripheral surface portion 31b, and arc surface portion) provided on the hub wheel 3. 31c).

The dam portion 376 is provided in a substantially rectangular shape in a circumferential cross-sectional view, and is arranged so as to protrude radially outward while being in contact with the outer peripheral surface at the outer-side end portion of the outer ring 2 .
Further, the weir portion 376 is provided in the core metal 371 so as to cover the radially outer end portion of the collar portion 371d and the outer edge portion 371e.

In the outer side seal member 307 configured as described above, a plurality of protrusions 374a, 374a, .
The configuration of the protrusion 374a is the same as that of the protrusion 74a of the outer seal member 7 in the wheel bearing device 1 described above, so the description thereof will be omitted.

With such a configuration, the outer seal member 307 according to the third embodiment also allows the plurality of gaps D, D, . . . ) suppresses the differential pressure generated between the first lip space P1 located outside the inner axial lip 374 and the second lip space P2 located inside the inner axial lip 374 via the The grease Z (also see FIG. 3(b)) that has passed through the tip and been pushed out once can be recovered again.
As a result, it is possible to prevent the tip of the inner axial lip 374 from being worn by being attracted to the sliding surface of the hub wheel 3, which is the inner member, that is, the arcuate surface portion 31c.
Further, since the tip portion of the inner axial lip 374 can be prevented from being attracted to the arc surface portion 31c, an increase in rotational torque in the wheel bearing device 301 can be suppressed.

[Configuration of Wheel Bearing Device 401 (Fourth Embodiment)]
Next, the configuration of the wheel bearing device 401 according to the fourth embodiment will be described with reference to FIGS. 1 and 5(b).
In FIG. 1, a wheel bearing device 401 in the fourth embodiment has substantially the same configuration as the wheel bearing device 1 in the first embodiment described above. , a plurality of protrusions 474a (see FIG. 5B).
Therefore, in the following description, differences from the above-described wheel bearing device 1 will be mainly described, and descriptions of structures equivalent to the wheel bearing device 1 will be omitted.

As shown in FIG. 5B, the inner side seal member 406 includes a substantially cylindrical seal plate 406a, a substantially cylindrical slinger 406b, and the like.
Note that the main configurations of the seal plate 406a and the slinger 406b are the same as those of the seal plate 6a and the slinger 6b in the wheel bearing device 1 described above, so description thereof will be omitted.

The seal lip 406a1 is composed of an outer axial lip 473, an inner axial lip 474, and a radial lip 475 which are each formed in an annular shape and arranged coaxially.

The outer axial lip 473 is formed so as to incline radially outward and extend toward the axial inner side (see FIG. 1) in a circumferential cross-sectional view.
In addition, the inner axial lip 474 is positioned radially inward of the outer axial lip 473 and is formed so as to extend axially inward while being inclined radially outward in a circumferential cross-sectional view.
Further, the radial lip 475 is positioned radially inward of the inner axial lip 474 and is formed to extend radially inwardly and extend to the axial outer side (see FIG. 1) in a circumferential cross-sectional view. ing.

The tip portions of the outer axial lip 473 and the inner axial lip 474 are in sliding contact with the sliding surface of the inner ring 4 as an inner member, that is, the flat surface on the outer side of the slinger 406b.
Further, the radial lip 475 is brought into sliding contact with the sliding surface of the inner ring 4 as an inner member, that is, the outer peripheral surface of the slinger 406b at its tip.

In the inner side seal member 406 configured as described above, a plurality of projections 474a, 474a . . .
The configuration of the protrusion 474a is the same as the protrusion 74a of the outer side seal member 7 in the wheel bearing device 1 described above, so the description thereof will be omitted.

With such a configuration, even with the inner side seal member 406 in the fourth embodiment, a plurality of gaps D, D, . ) suppresses the differential pressure generated between the third lip space P3 located outside the inner axial lip 474 and the fourth lip space P4 located inside the inner axial lip 474 via the The grease Z (also see FIG. 3(b)) that has passed through the tip and been pushed out once can be recovered again.
As a result, it is possible to prevent the tip of the inner axial lip 474 from being worn by being attracted to the sliding surface of the inner ring 4, which is the inner member, that is, the flat surface on the outer side of the slinger 406b.
Further, since the tip portion of the inner axial lip 474 can be prevented from being attracted to the outer-side flat surface of the slinger 406b, an increase in rotational torque in the wheel bearing device 401 can be suppressed.

Furthermore, with the inner side seal member 406 in the fourth embodiment, for example, even if it is configured by a sealing device consisting of a so-called pack seal, the conventional axial lip (the outer axial lip in this embodiment) can be used. 473), it is not necessary to provide the slinger 406b with a curved extending portion that extends obliquely inward in the radial direction so as to cover the tip of the axial lip. is easy.

[Configuration of Wheel Bearing Device 501 (Fifth Embodiment)]
Next, the configuration of the wheel bearing device 501 according to the fifth embodiment will be described with reference to FIGS. 1 and 5(c).
In FIG. 1, a wheel bearing device 501 in the fifth embodiment has substantially the same configuration as the wheel bearing device 1 in the first embodiment, like the wheel bearing device 401 in the fourth embodiment. On the other hand, it differs from the wheel bearing device 1 mainly in that the seal lip 506a1 of the inner side seal member 506 is provided with a plurality of protrusions 574a (see FIG. 5(c)). do.
Therefore, in the following description, differences from the above-described wheel bearing device 1 will be mainly described, and descriptions of structures equivalent to the wheel bearing device 1 will be omitted.

As shown in FIG. 5C, the inner side seal member 506 includes a substantially cylindrical seal plate 506a, a substantially cylindrical slinger 506b, and the like.
Note that the main configurations of the seal plate 506a and the slinger 506b are the same as those of the seal plate 6a and the slinger 6b in the wheel bearing device 1 described above, and thus description thereof will be omitted.

The seal lip 506a1 is composed of an outer axial lip 573, an inner axial lip 574, and a radial lip 575 which are each formed in an annular shape and arranged coaxially.

The outer axial lip 573 is formed so as to incline radially outward and extend toward the axial inner side (see FIG. 1) in a circumferential cross-sectional view.
In addition, the inner axial lip 574 is positioned radially inward of the outer axial lip 573 and is formed so as to be inclined radially inward and extend axially inward in a circumferential cross-sectional view.
Further, the radial lip 575 is positioned radially inward of the outer axial lip 573 and is formed to extend radially inwardly and extend axially outward (see FIG. 1) in a circumferential cross-sectional view. ing.
It should be noted that the inner axial lip 574 is set so that its thickness increases toward the tip for the purpose of improving rigidity.

The tip portion of the outer axial lip 573 is in sliding contact with the sliding surface of the inner ring 4, which is the inner member, that is, the flat surface on the outer side of the slinger 506b.
In addition, the inner axial lip 574 and the radial lip 575 are brought into sliding contact with the sliding surface of the inner ring 4 as the inner member, that is, the outer peripheral surface of the slinger 506b at their distal ends.

In the inner side seal member 506 configured as described above, a plurality of projections 574a, 574a . . .
The configuration of the protrusion 574a is the same as that of the protrusion 74a of the outer side seal member 7 in the wheel bearing device 1 described above, so the description thereof will be omitted.

With such a configuration, even with the inner side seal member 506 in the fifth embodiment, a plurality of gaps D, D, . ) to suppress the differential pressure generated between the third lip space P3 located outside the inner axial lip 574 and the fourth lip space P4 located inside the inner axial lip 574. The grease Z (also see FIG. 3(b)) that has passed through the tip and been pushed out once can be recovered again.
As a result, the tip of the inner axial lip 574 can be prevented from being worn by being attracted to the sliding surface of the inner ring 4, ie, the outer peripheral surface of the slinger 506b.
Also, since the tip of the inner axial lip 574 can be prevented from being attracted to the outer peripheral surface of the slinger 506b, an increase in rotational torque in the wheel bearing device 501 can be suppressed.

Furthermore, with the inner side seal member 506 in the fifth embodiment, for example, even if it is configured by a sealing device consisting of a so-called pack seal, the conventional axial lip (the outer axial lip in this embodiment) can be used. 573), the slinger 506b does not need to be provided with a curved extending portion that extends obliquely inward in the radial direction so as to cover the tip of the axial lip. is easy.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments in any way, and is merely an example. Of course, the scope of the present invention is indicated by the description of the claims, and the meaning of equivalents described in the claims and all changes within the scope include.

1, 201, 301, 401, 501 wheel bearing device 2 outer ring (outer member)
2c outer raceway surface 3 hub wheel 3a small diameter stepped portion 3d, 4a inner raceway surface (inner member)
31a Flat portion (sliding surface)
31b shaft peripheral surface (sliding surface)
31c Arc surface portion (sliding surface)
4 inner ring 5 ball row (rolling element)
6, 406, 506 inner side seal member (seal member)
7, 207, 307 Outer-side sealing member (sealing member)
71, 371 Metal core 72, 372 Seal body 72b, 272b, 372b, 406a1, 506a1 Seal lip 73, 373, 473, 573 Outer axial lip 74, 274, 374, 474, 573 Inner axial lip 74a, 274a, 374a, 474a , 574a Projection 75, 375, 475, 575 Radial lip Q2 Annular space S1a Virtual arc Z Grease

Claims (4)

an outer member having a double-row outer raceway surface on its inner circumference;
A hub wheel having an axially extending small-diameter stepped portion on its outer periphery, and at least one inner ring press-fitted into the small-diameter stepped portion of the hub wheel. an inner member having a raceway surface;
double-row rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member;
A wheel bearing device comprising a sealing member that closes an open end of an annular space formed by the outer member and the inner member,
The sealing member is
a metal core fitted to the outer member;
A sealing body made of an elastic body joined to the core bar,
The seal body extends in the axial direction and has a seal lip that slidably contacts a sliding surface of the inner member at its distal end,
The distal end portion of the seal lip is provided with a plurality of protrusions that protrude toward the sliding surface and are arranged along the periphery of the distal end portion.
A wheel bearing device characterized by: Enclosed in the gap between the tip of the seal lip and the sliding surface,
a grease having a mixed consistency range of 175 to 385;
The wheel bearing device according to claim 1, characterized in that: The seal lip is
an outer axial lip inclined radially outwardly and extending in one axial direction;
an inner axial lip located radially inward of the outer axial lip and inclined radially outwardly and extending in one axial direction;
a radial lip positioned radially inward of the inner axial lip and inclined radially inwardly extending in the other axial direction;
The protrusion is provided at the tip of the inner axial lip,
The wheel bearing device according to claim 1 or 2, characterized in that: The plurality of protrusions are
From an axial view,
The center position of each protrusion in the circumferential direction is on the side opposite to the road surface, and is located on a virtual arc with a center angle α of more than 0° and 180° or less.
The wheel bearing device according to any one of claims 1 to 3, characterized in that:

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