JP2015143564A - Wheel support bearing unit with seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a structure suppressing the interference of a grease lip constituting a seal ring from increasing in response to an increase in the internal pressure of a bearing internal space.SOLUTION: A protrusion 30 is provided on an inner circumferential surface of a tip end portion of a grease lip 16a to protrude toward a seal slide surface. If an internal pressure of a bearing internal space 11 increases, then the protrusion 30 contacts the seal slide surface, and a tip end edge of the grease lip 16a then separates from the seal slide surface with the protrusion 30 acting as a fulcrum to generate a clearance. This clearance creates a state in which the bearing internal space 11 communicates with an outer space of the grease lip 16a, thereby discharging air in the bearing internal space 11 to the outside.

Description

  The present invention relates to an improvement of a bearing unit for supporting a wheel with a seal, which is used for rotatably supporting a wheel of an automobile with respect to a suspension device. Specifically, the life of the seal ring that closes the axial end opening of the bearing internal space is extended.

  2. Description of the Related Art Conventionally, a wheel support bearing unit with a seal having various structures has been used to support a vehicle wheel on a suspension device. 5 to 7 show an example of the conventional structure of such a sealed wheel supporting bearing unit. This sealed wheel support bearing unit includes an outer ring 1, a hub 2, a plurality of rolling elements 3, a seal ring 4, and a cover 5 made of a nonmagnetic plate.

  The outer ring 1 has double-row outer ring raceways 6a and 6b on the inner peripheral surface, and a stationary flange 7 on the outer peripheral surface. Such an outer ring 1 does not rotate while being supported by the suspension device by fixing the stationary flange 7 to a knuckle of the suspension device (not shown). The hub 2 is provided concentrically with the outer ring 1 on the inner diameter side of the outer ring 1, and the double-row inner ring raceways 8 a and 8 b are provided on the outer surface of the hub 2 facing the outer ring raceways 6 a and 6 b. Rotation side flanges 9 are respectively provided at portions that protrude outward in the axial direction from the outer ring 1. Such a hub 2 rotates together with the wheel and the braking member in a state where a braking member such as a wheel and a disk (not shown) is supported and fixed to the rotation side flange 9. Note that “outside” in the axial direction refers to the left side of each figure, which is the outer side in the width direction of the vehicle when assembled to the automobile. On the other hand, the right side of each figure, which is the center side in the width direction of the vehicle, is referred to as “inside” in the axial direction.

  A plurality of rolling elements 3 are provided between each outer ring raceway 6a, 6b and each inner ring raceway 8a, 8b so as to roll freely for each row. In the illustrated example, a ball is used as the rolling element 3. However, in the case of a wheel support bearing unit for an automobile that is heavy in weight, a tapered roller may be used instead of the ball. The seal ring 4 and the cover 5 are provided in a state of closing both axial end openings of the bearing internal space 11 existing between the inner peripheral surface of the outer ring 1 and the outer peripheral surface of the hub 2. The seal ring 4 and the cover 5 prevent foreign matter such as muddy water from entering the bearing inner space 11 and prevent the lubricating grease sealed in the bearing inner space 11 from leaking to the outside. Yes.

  The seal ring 4 has the same structure as the seal ring described in Patent Document 1 and the like that has been widely known. That is, the seal ring 4 that closes the axially outer end opening of the bearing internal space 11 includes a cored bar 12 and a seal material 13 as shown in detail in FIG. The cored bar 12 is made of a metal plate in an annular shape, and is fitted and fixed to the axially outer end of the outer ring 1. The sealing material 13 is formed in an annular shape by an elastic material such as an elastomer such as rubber, and is bonded and fixed to the entire circumference of the core metal 12.

  The seal material 13 includes three contact-type seal lips including a side lip 14, a main lip 15, and a grease lip 16, and a labyrinth slip 17 constituting a labyrinth seal. Of the contact-type seal lips 14 to 16, the side lip 14 and the main lip 15 are slid over the entire circumference on the radially inner end of the axially inner side surface of the rotation side flange 9, which is a seal sliding contact surface. It touches. The tip end edge of the grease lip 16 is entirely in contact with the seal sliding contact surface near the axially outer end of the outer peripheral surface of the hub 2 (the portion between the rotation-side flange 9 and the axially outer ring raceway 8a). It is in sliding contact with the circumference.

  A saddle-shaped labyrinth slip 17 is provided further radially outward than the side lip 14 provided at the outermost radial direction, and the inner peripheral surface of the tip end portion of the labyrinth slip 17 is formed on the step on the inner surface in the axial direction of the rotary flange 9. A labyrinth seal is formed in close proximity to the part over the entire circumference. Furthermore, a weir portion 18 that protrudes radially outward from the outer peripheral edge of the outer end surface in the axial direction of the outer ring 1 is provided in a portion of the sealing material 13 that is continuous from the base end portion of the labyrin slip 17. The weir portion 18 prevents moisture adhering to the outer peripheral surface of the outer ring 1 from reaching the outer peripheral surface of the labyrin slip 17 through the outer ring 1.

  With respect to the seal ring 4, the side lip 14 and the main lip 15 provided in the space on the opposite side of the bearing lip 11 of the grease lip 16 from the base end toward the tip edge are externally It is inclined in a direction toward the opposite side of the space 11. Thereby, the foreign substance intrusion prevention function by the side lip 14 and the main lip 15 is enhanced. Further, according to this configuration, the side lip 14 and the main lip 15 are easily leaked from the bearing inner space 11 side to the outside. On the other hand, the grease lip 16 is inclined in a direction toward the inside (the bearing inner space 11 side) from the outer diameter side edge as the base end toward the inner diameter side edge as the tip edge. This enhances the function of preventing leakage of grease sealed in the bearing internal space 11 by the grease lip 16.

An annular encoder 21 is fitted and fixed to the outer peripheral surface of the inner ring 20 constituting the hub 2 at the axially inner end of the hub 2. The encoder 21 is a permanent magnet such as a rubber magnet or a plastic magnet, and an inner surface in the axial direction, which is a detected surface, is alternately magnetized with N and S poles at equal intervals in the circumferential direction.
A cover 5 is fitted and fixed to the inner peripheral surface of the outer ring 1 on the inner side in the axial direction, and closes the axial inner end opening of the bearing internal space 11. This cover 5 is a non-magnetic austenitic stainless steel plate (SUS304 or the like) formed into a petri dish by pressing, and the disk-like bottom plate portion has a slight axis on the detected surface of the encoder 21. They are close to each other via a directional gap.

  A sensor holder 22 is attached to the inside of the cover 5 in the axial direction. The sensor holder 22 is formed by forming a rolled steel plate or the like into a petri dish by pressing, and then applying a rust prevention treatment such as cationic coating, and is fitted on the inner peripheral surface of the inner end portion in the axial direction of the outer ring 1. It is fixed. A sensor insertion hole 23 is formed at the bottom of the sensor holder 22 and a nut 24 is press-fitted and fixed. A sensor detection unit (not shown) is inserted into the sensor insertion hole 23, and the sensor is fastened and fixed to the nut 24 with the detection unit facing the detection surface of the encoder 21 through the cover 5. As a result, the rotational speed of the wheel is detected and used for control of an antilock brake system or the like of the automobile.

By the way, when assembling the above-described bearing unit for supporting a wheel with a seal, the cover 5 is attached to the inner side in the axial direction in a state where the seal ring 4 is mounted and the outer ring 1, the hub 2 and the plurality of rolling elements 3 are combined. And press fit into the outer ring 1. At this time, since the seal ring 4 that seals the axially outer end opening of the bearing internal space 11 is already mounted, the pressure in the bearing internal space 11 rises due to the press-fitting of the cover 5.
Further, in the case of a bearing unit for supporting a wheel with a seal, the temperature in the bearing inner space 11 changes with changes in the use environment and the operating state, and the bearing inner space 11 in accordance with Boyle Charles's law is changed. Pressure changes. In particular, when the rolling bearing unit for supporting a wheel with a seal is cold-started (started from a state where the temperature is sufficiently lowered), the pressure in the bearing internal space 11 rises rapidly.

The grease lip 16 constituting the seal ring 4 is provided at a position in contact with the bearing internal space 11, that is, a position for directly receiving the pressure in the bearing internal space 11. For this reason, when the pressure in the bearing internal space 11 changes, the posture of the grease lip 16 changes elastically. In particular, when the pressure in the bearing internal space 11 rises rapidly, the posture of the grease lip 16 changes elastically as shown in FIG. That is, the tip end portion of the grease lip 16 is elastically deformed in a direction in which the angle between the inner peripheral surface and the seal sliding contact surface becomes smaller, and is pressed against the seal sliding contact surface with a wider contact area (tightening allowance). Is increased). As a result, the frictional force acting on the sliding contact portion between the tip end portion of the grease lip 16 and the seal sliding contact surface is increased, resulting in a decrease in fuel consumption, and the wear of the grease lip 16 is promoted, and the life of the grease lip 16 is increased. Cause a decline.
Further, the cover 5 fitted and fixed to the outer ring 1 may be displaced inward in the axial direction (outside of the bearing) due to an increase in the internal pressure of the bearing internal space 11.

JP 2012-131458 A

  In view of the circumstances as described above, the present invention suppresses an increase in the tightening margin of the grease lip constituting the seal ring that closes the axial end opening of the bearing inner space with a change in pressure in the bearing inner space. Invented to realize the structure to be realized.

In order to solve the above problems, the sealed wheel support bearing unit of the present invention includes an outer ring having a double row outer ring raceway on the inner peripheral surface, a double row inner ring raceway on the outer peripheral surface, and a wheel on the outer side in the axial direction. A hub having rotation-side flanges for supporting and fixing; a plurality of rolling elements each provided between the outer ring raceways and the inner ring raceways so as to be capable of rolling; and an inner peripheral surface of the outer ring. And a seal ring that closes an axial end opening of a bearing internal space existing between the outer peripheral surface of the hub. The seal ring includes an annular cored bar fixed to an axial end portion of the outer ring, and a sealing material fixed to the entire circumference of the cored bar. A seal lip is provided, and a tip end edge of a grease lip, which is a seal lip disposed at a position in contact with the bearing internal space among the seal lips, is arranged on the seal sliding contact surface provided on the outer peripheral surface of the hub. And the grease lip is moved closer to the axially central side of the inner space of the bearing as the grease lip is moved from the outer diameter side edge as the base end toward the inner diameter side edge as the tip edge. It is inclined in the direction of heading.
In particular, the bearing unit for supporting a wheel with a seal according to the present invention includes a valve mechanism that opens and closes due to a change in the angle between the tip of the grease lip and the seal sliding contact surface in accordance with a pressure change in the bearing internal space. Provided at the tip of the grease lip.

Further, the valve mechanism is a projection provided at the tip of the grease lip, and when the pressure in the bearing internal space rises, the projection serves as a fulcrum, and the tip edge of the grease lip and the seal slide The moving surface is spaced apart and the bearing internal space communicates with the outside.
The valve mechanism is an axially extending ventilation groove provided at the tip of the grease lip, and when the pressure in the bearing internal space rises, the inner circumferential surface of the ventilation groove is The bearing inner space communicates with the outside through the ventilation groove in sliding contact with the seal sliding surface.
Further, the seal material includes a side lip and a main lip which are the seal lips in a space opposite to the bearing internal space of the grease lip. The valve mechanism is slidably brought into contact with the entire surface, and is inclined in a direction toward the opposite side to the bearing internal space from the base end portion toward the tip end edge. It is provided at the tip.

  According to the sealed wheel supporting bearing unit of the present invention configured as described above, it is possible to suppress an increase in the tightening allowance of the grease lip constituting the seal ring as the pressure in the bearing internal space increases. That is, in the case of the present invention, when the pressure in the bearing internal space increases, the angle between the tip of the grease lip and the seal sliding contact surface is affected by the elastic change in the posture of the grease lip. Becomes smaller. As a result, the valve mechanism provided at the tip of the grease lip is activated to be opened, and the air in the bearing internal space is discharged to the outside. For this reason, an increase in pressure in the bearing internal space is suppressed, and an increase in gray slip tightening margin can be suppressed. Therefore, an increase in the frictional force acting on the tip of the grease lip and the seal sliding surface can be suppressed, and fuel efficiency can be improved accordingly. At the same time, the promotion of wear of the grease lip can be suppressed, and the life of the grease lip can be extended accordingly. Furthermore, the displacement of the cover 5 can be prevented, and sealing performance and reliability of rotation speed detection can be ensured.

The partial sectional view of the grease lip portion showing the first embodiment (a), when the pressure in the bearing internal space is increased (b), and when the pressure in the bearing internal space is decreased (c). The partial sectional view (a) of the grease lip portion showing the second embodiment, when the pressure in the bearing inner space is increased (b), and when the pressure in the bearing inner space is decreased (c). The partial sectional view (a) of the grease lip portion showing the third embodiment, the view (b) of the grease lip seen from the inner diameter side, and the modification (c). Sectional drawing of the seal ring which shows 4th Embodiment. Sectional drawing which shows an example of the conventional structure of the bearing unit for wheel support with a seal. The fragmentary sectional view of the seal ring of FIG. The enlarged view which shows the front-end | tip part of a grease lip of FIG. 5 in the state after the pressure in a bearing internal space rose.

[First Embodiment]
FIG. 1 shows a first embodiment of the present invention. The feature of this embodiment is that the structure of the tip of the grease lip 16a that constitutes the seal ring 4a that closes the axially outer end opening of the bearing internal space 11 is devised. Since the structure and operation of the other parts are the same as in the case of the conventional structure shown in FIGS. 5 to 7, the same reference numerals are given to the equivalent parts, and overlapping illustrations and explanations are omitted. In the following, the description will be focused on the characteristic portions of this example.

  In the case of the present embodiment, as shown in FIG. 1 (a), at the tip end portion of the grease lip 16a, the tip end of the grease lip 16a that is in sliding contact with the outer peripheral surface of the hub 2 is slightly axially outer (with the bearing internal space 11 and On the opposite side) is provided with a protrusion 30 which is a valve mechanism. A plurality of protrusions 30 are provided on the inner peripheral surface of the tip of the grease lip 16a in the circumferential direction in a state protruding radially inward, and the pressure in the bearing internal space 11 is normally (atmospheric pressure and atmospheric pressure). In the case of the same degree), there is a slight gap between the tip portion of the protrusion 30 and the outer peripheral surface of the hub 2 which is the seal sliding surface. Therefore, when the pressure in the bearing internal space 11 is normal, only the tip edge of the grease lip 16a is in sliding contact with the seal sliding surface, so that the grease sealed in the bearing internal space 11 leaks to the outside. The frictional resistance of the grease lip 16a does not increase.

  According to the sealed wheel supporting bearing unit of the present embodiment configured as described above, the tightening allowance of the grease lip 16a constituting the seal ring 4 increases as the pressure in the bearing inner space 11 increases. It can be suppressed. In other words, the inner peripheral surface of the tip of the grease lip 16a is provided with a protrusion 30 that protrudes toward the seal sliding surface. For this reason, when the pressure in the bearing internal space 11 rises, the grease lip 16a is influenced by the direction in which the angle of intersection between the inner peripheral surface of the tip and the central axis of the bearing unit decreases (radial direction). The inner peripheral surface of the tip portion of the grease lip 16a and the seal sliding contact surface (that is, the protrusion 30 and the seal sliding surface) are close to each other with the elastic change to the inwardly convex shape. To do. When the pressure further increases after the protrusion 30 and the seal sliding surface come into contact with each other, as shown in FIG. 1B, the protrusion 30 serves as a fulcrum and the tip edge of the grease lip 16a is separated from the seal sliding surface. Gaps. Due to this gap, the bearing inner space 11 and the outer space of the grease lip 16a communicate with each other, and the air in the bearing inner space 11 is discharged to the outside. Accordingly, when the pressure in the bearing internal space 11 is reduced, the grease lip 16a is elastically deformed and returns to the normal shape shown in FIG. Since the side lip 14 and the main lip 15 existing on the outer side of the grease lip 16a are configured to easily leak from the bearing inner space 11 toward the outer side, the air passing through the grease lip 16a It passes through the lip 14 and the main lip 15 and is exhausted to the atmosphere.

  On the other hand, when the pressure in the bearing internal space 11 decreases due to a decrease in the bearing temperature or the like, the posture of the grease lip 16a becomes elastic in the direction in which the angle of intersection between the inner peripheral surface of the tip and the central axis of the bearing unit increases. Along with the change, as shown in FIG. 1C, the inner peripheral surface of the tip of the grease lip 16a and the seal sliding contact surface are largely separated. At this time, the protrusion 30 and the seal sliding surface are not in contact with each other, the tip edge of the grease lip 16a and the seal sliding surface are kept in sliding contact with each other, and the tightening margin of the grease lip 16a is not increased. .

  As described above, even when the pressure in the bearing internal space 11 suddenly rises at the time of assembling the bearing or at the cold start, the increase in the tightening margin of the grease lip 16a is suppressed by the protrusion 30 that is the valve mechanism. doing. Therefore, an increase in the frictional force acting on the tip of the grease lip 16a and the outer peripheral surface of the hub 2, which is a seal sliding surface, can be suppressed, and fuel efficiency can be improved accordingly. At the same time, the acceleration of wear of the grease lip 16a can be suppressed, and the life of the grease lip 16a can be extended accordingly. Furthermore, the axial displacement of the cover 5 due to an increase in pressure can be prevented.

When only the pressure increase in the bearing internal space 11 due to the press-fitting of the cover 5 at the time of bearing assembly is prevented, the protrusion amount of the protrusion 30 is the wear of the grease lip 16a accompanying the use of the bearing unit for supporting the wheel with seal. At the same time, the amount of protrusion can be small enough to wear out and disappear.
In the above embodiment, the plurality of protrusions 30 are provided at the tip of the grease lip 16a. However, only one protrusion 30 may be provided. When a plurality of protrusions 30 are provided, the positions of the protrusions 30 in the axial direction may be slightly different, and the height (projection amount) of the protrusions 30 may be changed accordingly.

[Second Embodiment]
FIG. 2 shows a second embodiment of the present invention. In the case of the present embodiment, as shown in FIG. 2 (a), at the tip end portion of the grease lip 16b, the valve portion is formed slightly on the axially outer portion from the tip edge of the grease lip 16b slidably contacting the outer peripheral surface of the hub 2. A ventilation groove 31 as a mechanism is provided. The ventilation groove 31 is provided on the inner peripheral surface of the tip portion of the grease lip 16b in a state of being recessed in the radially outward direction and extending in the axial direction in the circumferential direction. When the pressure in the internal space 11 is normal, there is a slight gap between the inner peripheral surface portion of the ventilation groove 31 and the outer peripheral surface of the hub 2 that is the seal sliding surface. Therefore, when the pressure in the bearing internal space 11 is normal, only the tip edge of the grease lip 16b is in sliding contact with the seal sliding surface, so that the grease sealed in the bearing internal space 11 leaks to the outside. The frictional resistance of the grease lip 16b does not increase.

  When the pressure in the bearing internal space 11 rises, the grease lip 16b is changed in posture in a direction in which the angle between the inner peripheral surface of the tip end portion and the center axis of the bearing unit is reduced. The inner peripheral surface of the tip end portion of 16b and the seal sliding contact surface (that is, the ventilation groove 31 and the seal sliding surface) are close to each other. When the pressure further rises after the inner peripheral surface of the ventilation groove 31 comes into contact with the seal sliding surface, the inner peripheral surface portion of the ventilation groove 31 serves as a fulcrum as shown in FIG. A gap is generated when the tip edge of the seal member is separated from the seal sliding surface. The clearance and the ventilation groove 31 allow the bearing inner space 11 to communicate with the outer space of the grease lip 16b, and the air in the bearing inner space 11 passes through the side lip 14 and the main lip 15 and is discharged to the outside. Is done. Thereby, when the pressure in the bearing internal space 11 is reduced, the grease lip 16b is elastically deformed and returns to the normal shape shown in FIG.

  On the other hand, when the pressure in the bearing internal space 11 decreases due to a decrease in the bearing temperature or the like, the posture of the grease lip 16b becomes elastic in the direction in which the angle of intersection between the inner peripheral surface of the tip and the central axis of the bearing unit increases. With the change, as shown in FIG. 2C, the inner peripheral surface of the tip of the grease lip 16b and the seal sliding contact surface are greatly separated. At this time, the ventilation groove 31 and the seal sliding surface are not in contact with each other, the tip edge of the grease lip 16b and the seal sliding surface are kept in sliding contact, and the tightening margin of the grease lip 16b may be increased. Absent.

In order to prevent only the pressure increase in the bearing internal space 11 due to the press-fitting of the cover 5 during the assembly of the bearing, the groove depth of the ventilation groove 31 is the grease lip 16b associated with the use of the bearing unit for supporting a wheel with seal. It is also possible to make the groove depth such that it wears out and disappears with the wear.
In the above embodiment, the plurality of ventilation grooves 31 are provided at the tip of the grease lip 16b. However, only one ventilation groove 31 may be provided.
Other configurations and operations are the same as in the case of the first embodiment described above, and therefore illustrations and descriptions regarding equivalent parts are omitted.

[Third Embodiment]
FIG. 3 shows a third embodiment of the present invention. In the case of the present embodiment, as shown in FIG. 3 (a), at the tip end portion of the grease lip 16c, the valve lip slightly extends from the tip edge of the grease lip 16c slidably contacting the outer peripheral surface of the hub 2 to the axially outer portion. The protrusion 32 which is a mechanism is provided. A plurality of protrusions 32 are provided on the inner peripheral surface of the tip end portion of the grease lip 16c in a state of projecting radially inward in the circumferential direction, and the pressure in the bearing internal space 11 is normal. In this case, a slight gap exists between the inner peripheral surface portion of the protrusion 32 and the outer peripheral surface of the hub 2 which is a seal sliding surface. And as shown in FIG.3 (b), this protrusion 32 is made into the V shape which becomes wide as it goes to an axial direction outer side seeing from radial inside.

  When the pressure in the bearing internal space 11 is increased, the grease lip 16c is elastically changed in the direction in which the angle of intersection between the inner peripheral surface of the tip and the center axis of the bearing unit becomes smaller. The inner peripheral surface of the tip portion of 16c and the seal sliding contact surface are close to each other. Then, the protrusion 32 serves as a fulcrum and the tip edge of the grease lip 16c is separated from the seal sliding surface to generate a gap. Due to this gap and the circumferential gap between the protrusions 32, the bearing inner space 11 and the outer space of the grease lip 16c communicate with each other, and the air in the bearing inner space 11 is discharged to the outside. At this time, the grease sealed in the bearing internal space 11 together with air tends to leak to the outside, but each side of the V-shaped protrusion 32 pushes the grease back into the bearing internal space 11, so that the grease leaks. Is preventing.

FIG. 3C shows a modification of the present embodiment. In the case of this modification, the number of the V-shaped protrusions 32a is reduced, and a part of the protrusions 32 is made continuous by a circumferential convex shape. With this configuration, the degree to which the frictional resistance of the seal increases when the pressure in the bearing internal space 11 increases and the protrusion 32a comes into sliding contact with the seal sliding surface is suppressed.
Other configurations and operations are the same as in the case of the first embodiment described above, and therefore illustrations and descriptions regarding equivalent parts are omitted.

[Fourth Embodiment]
FIG. 4 shows a fourth embodiment of the present invention. In the case of the seal ring 4d of the present embodiment, in addition to the protrusions 30 provided on the grease lip 16a of the first embodiment described above, a slightly axially inner portion from each tip edge of the side lip 14a and the main lip 15a, Protrusions 30a and 30b, which are valve mechanisms, are provided. A plurality of protrusions 30a provided on the side lip 14a and protrusions 30b provided on the main lip 15a protrude radially inward in the circumferential direction on the inner peripheral surface of the tip of each lip. Is provided. When the pressure in the first seal space 33 formed by the main lip 14a, the side lip 15a, and the outer peripheral surface of the hub 2 is normal (substantially equal to atmospheric pressure), the tip portion of the protrusion 30a and the seal sliding surface A slight gap exists between the outer peripheral surface of a certain hub 2. In addition, when the pressure in the second seal space 34 formed by the side lip 15a, the grease lip 16a, and the outer peripheral surface of the hub 2 is normal, there is a slight gap between the tip portion of the protrusion 30b and the outer peripheral surface of the hub 2. There is a gap.

  When the pressure in the bearing internal space 11 decreases, the pressure of the second seal space 34 decreases as the posture of the grease lip 16a is elastically deformed as shown in FIG. The inner peripheral surface of the part and the seal sliding contact surface are close to each other. The protrusion 30b serves as a fulcrum, and the leading edge of the main lip 15a is separated from the seal sliding surface to generate a gap. Due to this gap, the second seal space 34 and the first seal space 33 communicate with each other, and air flows from the first seal space 33 into the second seal space 34. Along with this, the pressure in the first seal space 33 decreases, but the protrusion 30a serves as a fulcrum, and the tip edge of the side lip 14a is separated from the seal sliding surface to generate a gap. By this gap, the first seal space 33 and the external space are in communication with each other, and air flows into the first seal space 33 from the external space.

With the above configuration, even when the pressure in the bearing internal space 11 is reduced, the protrusions 30a and 30b that are valve mechanisms prevent the side lip 14a and the main lip 15a from being tightened. Therefore, it is possible to suppress an increase in the rotational torque due to an increase in the frictional force acting on the front ends of the side lip 14a and the main lip 15a and the outer peripheral surface of the hub 2 which is the seal sliding surface. In addition, the valve mechanism provided in each lip of the present embodiment can be applied by arbitrarily combining the configurations of the valve mechanisms of the second and third embodiments described above.
Other configurations and operations are the same as in the case of the first embodiment described above, and therefore illustrations and descriptions regarding equivalent parts are omitted.

The present invention is applicable to a bearing unit for supporting a wheel with a seal having various structures for rotatably supporting a wheel of an automobile.
For example, the present invention provides a wheel support with a seal for a drive wheel in which the axially outer end opening is closed with a seal ring and the axially inner end opening is closed with a combination seal ring among the axially opposite end openings of the bearing internal space. The present invention can also be applied to a bearing unit for a wheel and a bearing unit for supporting a wheel with a seal in which both ends in the axial direction of the inner space of the bearing are closed with a combination seal ring.
In the case of a combined seal ring, the present invention is applied to a grease lip that constitutes a seal ring that is slidably contacted with a slinger fitted and fixed to a hub and fitted and fixed to an outer ring.

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Hub 3 Rolling element 4, 4a, 4b, 4c, 4d Seal ring 5 Cover 6a, 6b Outer ring raceway 7 Static side flange 8a, 8b Inner ring raceway 9 Rotation side flange 11 Bearing inner space 12 Core metal 13 Sealing material 14, 14a Side lip 15, 15a Main lip 16, 16a, 16b, 16c, 16d Grease lip 17 Labyrinth slip 18 Weir 20 Inner ring 21 Encoder 22 Sensor holder 23 Sensor insertion hole 24 Nut 30, 30a, 30b Protrusion 31 Ventilation groove 32, 32a Projection 33 First seal space 34 Second seal space

Claims (4)

An outer ring having a double row outer ring raceway on the inner peripheral surface, a hub having a double side inner ring raceway on the outer peripheral surface, and a rotation side flange for supporting and fixing the wheel on the outside in the axial direction; and each outer ring raceway, A plurality of rolling elements provided between each of the inner ring raceways so as to be freely rotatable, and an axial end opening of a bearing inner space existing between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub A seal ring that closes the outer ring, and the seal ring includes an annular metal core fixed to the axial end of the outer ring, and a seal material fixed to the entire circumference of the metal core, The seal material includes a plurality of seal lips, and a tip edge of a grease lip which is a seal lip disposed at a position in contact with the bearing internal space among the seal lips is provided on the outer peripheral surface of the hub. Slid over the entire circumference of the seal sliding surface And the grease lip is inclined in the direction toward the axially central side of the bearing internal space as it goes from the outer diameter side edge as the base end to the inner diameter side edge as the tip edge. In the sealed wheel support bearing unit,
A valve mechanism that opens and closes when the angle between the tip of the grease lip and the seal sliding contact surface changes in accordance with the pressure change in the bearing internal space is provided at the tip of the grease lip. Bearing unit for wheel support with seal.   The valve mechanism is a protrusion provided at the tip of the grease lip, and when the pressure in the bearing internal space rises, the protrusion serves as a fulcrum, and the tip edge of the grease lip and the seal sliding surface The wheel support bearing unit with a seal according to claim 1, wherein the bearing inner space communicates with the outside.   The valve mechanism is an axially extending ventilation groove provided at the tip of the grease lip, and when the pressure in the bearing internal space rises, the inner peripheral surface of the ventilation groove is The bearing unit for wheel support with a seal according to claim 1, wherein the bearing inner space communicates with the outside through the ventilation groove in sliding contact with the moving surface.   The seal material includes a side lip and a main lip that are the seal lips in a space opposite to the bearing internal space of the grease lip, and a tip edge of the seal lip is formed on the seal sliding contact surface. The valve mechanism is slidably contacted over the entire circumference, and is inclined in a direction toward the opposite side of the bearing internal space from the proximal end portion toward the distal end edge. The bearing unit for supporting a wheel with a seal according to claim 1, wherein the bearing unit is provided at a portion.

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