JP6597353B2 - Rolling bearing unit for wheel support - Google Patents

Description

  The present invention relates to an improvement of a wheel bearing rolling bearing unit for rotatably supporting a vehicle wheel with respect to a suspension device.

  A vehicle wheel and a braking rotator are rotatably supported with respect to a suspension device by a wheel bearing rolling bearing unit described in, for example, Patent Literatures 1 and 2. Among these, the wheel-supporting rolling bearing unit described in Patent Document 1 has through-holes at a plurality of locations in the circumferential direction of the radial intermediate portion of the rotation-side flange constituting the hub. A wheel and a braking rotator (not shown) are coupled and fixed to the outer surface in the axial direction of the rotation-side flange by a plurality of studs and nuts inserted through the through holes from the inner side in the axial direction. In this state, the heads of these studs protrude inward in the axial direction from the axially inner surface of the rotation side flange. The amount of protrusion of each stud head from the axial inner surface of the rotating flange varies depending on the weight of the vehicle and the diameter (outer diameter) of the wheel and brake rotating body. In the case of a rolling bearing unit for supporting a wheel, it is about 4 to 7 mm. In the case of such a structure described in Patent Document 1, the head of each stud and the axial outer end of the outer ring are overlapped in the radial direction (the head of each stud is axially aligned with the outer ring. By locating the outer end portion in the radial direction), the wheel support rolling bearing unit is reduced in size in the axial direction so as to be miniaturized. Therefore, the outer diameter of the outer end in the axial direction of the outer ring cannot be increased, and the size of the pitch circle diameter of the rolling elements (especially the rolling elements in the outer row in the axial direction) is limited, and the degree of freedom in design. Is limited.

  In the present specification and claims, “outside” in the axial direction means the outside in the width direction of the vehicle in the assembled state to the automobile, and the left side of each figure. On the contrary, 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.

  On the other hand, Patent Document 2 can secure the degree of freedom of design while reducing the size of the wheel bearing rolling bearing unit by supporting and fixing the wheel and the braking rotator to the rotation side flange with bolts. The structure is described. FIG. 5 shows a wheel bearing rolling bearing unit for driving wheels described in Patent Document 2. The wheel support rolling bearing unit 1 includes an outer ring 2, a hub 3, and a plurality of rolling elements 4 and 4. Of these, the outer ring 2 is provided with double-row outer ring raceways 5a and 5b on the inner peripheral surface and a stationary flange 6 on the axially intermediate portion of the outer peripheral surface. Through holes 7 through which bolts for connecting and fixing the outer ring 2 to a suspension device are provided at a plurality of locations in the circumferential middle portion of the stationary flange 6.

  The hub 3 is a combination of a hub body 8 and an inner ring 9, and is arranged coaxially with the outer ring 2 on the radially inner side of the outer ring 2. The hub body 8 has a rotation-side flange 10 on the outer peripheral surface of the outer ring 2 that protrudes outward in the axial direction from the axial end of the outer ring 2, and the shaft of the double-row outer ring raceways 5 a and 5 b. The inner ring raceway 11a in the axially outer row is provided at the axially intermediate portion facing the outer ring raceway 5a in the outer side row, and the small-diameter step portion 12 is also provided at the inner end portion in the axial direction. And the screw hole 13 is provided in the circumferential direction several places of the radial direction intermediate part of the said rotation side flange 10. As shown in FIG. A spline hole 34 is provided at the center of the hub body 8 for engaging the spline shaft portion constituting the constant velocity joint with the spline. The inner ring 9 is provided with an inner ring raceway 11b in the inner row in the axial direction on the outer peripheral surface, and is fitted and fixed to the small-diameter step portion 12.

  Each of the rolling elements 4, 4 is held between the double row outer ring raceways 5a, 5b and the double row inner ring raceways 11a, 11b by the cages 14a, 14b. A plurality of rolls are provided for each roll.

  The wheel-supporting rolling bearing unit 1 includes a plurality of bolts through which a wheel and a braking rotator are inserted in the axially outer side surface of the rotation-side flange 10 and through holes provided in the wheel and the braking rotator. Then, it is coupled and fixed to the screw hole 13 of the rotation side flange 10 by screwing from the outside in the axial direction and further tightening. In this state, the front end face (axial inner end face) of each bolt is positioned axially outward from the axial inner face of the rotation side flange 10, and the front end part (axial inner end face) of each bolt is placed. Portion) regulates the length of the shaft portion of each of the bolts so that it does not protrude from the inner surface in the axial direction of the rotation side flange 10.

  Furthermore, an axial outer end opening is provided between the axially opposite end openings of the inner space 15 that exists between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3 and in which the rolling elements 4 and 4 are provided. The portion is closed by a seal ring 16 and the axially inner end opening of the internal space 15 is closed by a combination seal ring 28 formed by combining a seal ring and a slinger. This prevents foreign matter such as dust and rainwater from entering the internal space 15 and prevents the grease filled in the internal space 15 from leaking to the external space. The seal ring 16 includes a metal core 17 and a seal material 18. Of these, the metal core 17 is made of a metal plate such as a mild steel plate, and includes a fitting tube portion 19, an annular portion 20 that is bent radially outward from an axial outer end edge of the fitting tube portion 19, and A bent portion 21 that is folded back in a U shape from the inner end edge in the axial direction of the fitting cylinder portion 19 toward the radially inner side and the axially outer side is provided. Of these, the fitting cylinder portion 19 is fitted and fixed to the inner peripheral surface of the outer end portion 2 of the outer ring 2 by an interference fit, and the inner side surface in the axial direction of the annular portion 20 is fixed to the outer periphery of the outer ring 2. The end surface is abutted with a part of the sealing material 18 interposed therebetween.

  This sealing material 18 is made of an elastic material such as an elastomer such as rubber, and is bonded and fixed to the cored bar 17. The labyrinth slip 23 is provided. Each of the seal lips 22a to 22c is slidably brought into contact with the inner peripheral surface of the rotation side flange 10 or the outer peripheral surface of the intermediate portion of the hub 3 over the entire circumference. On the other hand, the labyrinth slip 23 is provided further radially outward than the seal lip 22a provided on the outermost radial direction among the seal lips 22a to 22c. The labyrinth slip 23 is positioned radially outward from a stepped portion 24 provided on a proximal end portion (radially inward portion) of the axially inner side surface of the rotation side flange 10 so that the labyrinth is located. The front half of the lip 23 (the outer half in the axial direction) and the stepped portion 24 are overlapped in the radial direction. And the front end surface of the labyrinth slip 23 and the inner peripheral surface of the front end portion, and the inner side surface in the axial direction of the rotation side flange 10 (of which the portion existing inside the screw hole 13 with respect to the radial direction of the hub 3). And the outer peripheral surface of the step portion 24 are closely opposed over the entire circumference, the tip surface of the labyrin slip 23 and the inner peripheral surface of the tip portion, the inner surface in the axial direction of the rotary flange 10 and the step portion 24. A labyrinth seal 25 is provided between the outer peripheral surface. Of the sealing material 18 that constitutes the seal ring 16, the portion that continues radially outward from the base end portion of the labyrinth slip 23 and the annular portion 20 that constitutes the core metal 17. A portion 26 that protrudes radially outward from the axially outer end surface of the outer ring 2 is covered, and a dam portion 26 is provided in the portion to block water from entering.

  In the case of the illustrated example, the combined seal ring 28, covering the axial inner end opening of the inner space 15 with an annular cover 27 fitted and fixed to the axial inner end of the inner ring 9, As a result, the durability of the wheel-supporting rolling bearing unit 1 as a whole is improved.

  In the case of the structure described in Patent Document 2 as described above, the wheel support rolling bearing unit 1 is configured so that the front end portion of each bolt does not protrude from the inner surface in the axial direction of the rotation side flange 10. The design freedom can be ensured while downsizing. However, there is room for further improvement in terms of improving the effect of preventing the entry of foreign matter such as dust and rainwater from the axially outer end opening of the internal space 15 into the internal space 15.

JP 2009-132207 A JP 2014-142054 A

  In view of the circumstances as described above, the present invention realizes the structure of a wheel bearing rolling bearing unit that can further improve the effect of preventing the entry of foreign matter into the internal space while ensuring the degree of freedom of design. The purpose is to do.

The wheel support rolling bearing unit of the present invention includes an outer ring, a hub, a plurality of rolling elements, a plurality of bolts, and a seal ring.
Among these, the outer ring has a double row outer ring raceway on the inner peripheral surface, and is not supported by the suspension device in use and does not rotate.
The hub has a double-row inner ring raceway and a rotation side flange, and is arranged coaxially with the outer ring on the radially inner side of the outer ring. Of these, the double-row inner ring raceway is provided in a portion of the outer peripheral surface of the hub facing the double-row outer ring raceway. The rotation-side flange is provided in a portion of the outer peripheral surface of the hub that protrudes outward in the axial direction from the outer end portion in the axial direction of the outer ring, and screw holes are provided at a plurality of circumferential positions in the radial intermediate portion. Is provided.
Each of the rolling elements is provided between the double row outer ring raceway and the double row inner ring raceway so as to be freely rollable in each row.
Each of the bolts is for fixing the wheel and the braking rotator to the rotation-side flange, and is screwed into the screw hole in a state where the tip end surface (the axial inner end surface) faces inward in the axial direction. Are combined. That is, each bolt is screwed into the screw hole of the rotation side flange from the outside in the axial direction.
The seal ring closes an axially outer end opening of an inner space existing between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub, and is fixed to the axially outer end portion of the outer ring. And a sealing material made of an elastic material reinforced by the core metal. Among these, the seal material is provided on the axially inner side surface of the rotation side flange or the outer peripheral surface of the hub over the entire circumference, the seal lip is provided radially outward from the seal lip, and the tip edge (shaft And a heel lip whose outer end edge in the direction is close to and opposed to the inner side surface in the axial direction of the rotary flange.

  In particular, in the wheel bearing rolling bearing unit of the present invention, at least a part of the front end surface of each bolt is positioned axially outward from the axial inner surface of the rotating flange (this Recessed axially outward from the axially inner surface of the rotating flange). The tip edge of the flange lip is a portion of the tip surface of each bolt that is positioned axially outward from the axial inner surface of the rotating flange (more than the axial inner surface of the rotating flange). The axially inner side surface of the rotating side flange is located close to and opposed to the axial side surface of the rotating side flange at a position aligned with the axially outwardly recessed portion).

When the rolling bearing unit for supporting a wheel according to the present invention as described above is implemented, specifically, for example, in a state where the wheel and the brake rotating body are coupled and fixed to the rotation side flange by the bolts. The axial lengths of the threaded portions of these bolts are regulated so that the entire front end surfaces of these bolts are positioned axially outward from the axial inner surface of the rotating flange.
Or the recessed part dented in the axial direction outward is provided in the front end surface of each bolt.
Alternatively, the rotation-side flange is formed by continuously forming a thick portion provided in the radially inner portion and a thin portion provided in the radially outer portion by a step portion provided on the inner side surface in the axial direction. Of the inner end opening in the axial direction of the screw hole, an inner portion in the radial direction of the hub is opened in the stepped portion. And the front-end | tip edge of the said collar lip is made to oppose to the step part while adjoining the inner part regarding the radial direction of the said hub among the front end surfaces of each said volt | bolt.

According to the wheel support rolling bearing unit of the present invention as described above, it is possible to further improve the effect of preventing the entry of foreign matter into the internal space where the rolling elements are installed while ensuring the degree of freedom of design.
Of these, the degree of freedom in design can be ensured for the same reason as the conventional structure shown in FIG. That is, the wheel support rolling bearing unit according to the present invention includes a plurality of bolts in which a wheel and a braking rotator are screwed into the axially outer side surface of the rotating side flange and the screw holes of the rotating side flange from the axially outer side. Bonded and fixed. Therefore, as in the conventional structure shown in FIG. 5, the tip of each bolt does not protrude from the inner surface in the axial direction of the rotating flange, and the wheel-supporting rolling bearing unit can be downsized. However, it is possible to ensure the degree of freedom of design. Furthermore, in the case of the present invention, it is not necessary to provide a seating surface for contacting the axially outer surface of the head portion of the stud on the axially inner surface of the rotating side flange. Compared with the described structure, the axial thickness of the intermediate portion in the radial direction of the rotating side flange can be increased, and the strength and rigidity of the rotating side flange can be improved.

  Further, when the rotation side flange rotates during operation of the wheel support rolling bearing unit, the axial inner side surface of the rotation side flange (and the front end surface of each bolt supported and fixed to the rotation side flange), An air flow is generated between the tip edge of the collar lip constituting the seal ring supported and fixed to the outer end portion in the axial direction of the outer ring. Due to this air flow, foreign matter adhering to the surface of the heel lip, such as being splashed up when the vehicle is running, is attracted to the rotating flange side. In the case of the present invention, at least a part of the front end surface of each bolt is positioned axially outward from the axial inner surface of the rotating flange. For this reason, in the portion where the tip edge of the collar lip and the portion of the tip surface of each bolt facing the portion located axially outward from the inner surface of the rotation side flange face each other in the circumferential direction. The velocity of the airflow is smaller (slower) than the detached portion, and the pressure is increased. Accordingly, the foreign matter attracted to the rotating flange side by the action of the airflow is discharged to the external space by the action of the pressure and centrifugal force. As a result, the effect of preventing the entry of foreign matter into the internal space can be further improved.

Sectional drawing which shows the 1st example of embodiment of this invention. The X section enlarged view of FIG. The figure equivalent to FIG. 2 which shows the 2nd example of embodiment of this invention. The figure which shows the 3rd example and corresponds to FIG. Sectional drawing which shows an example of a conventional structure.

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention. The wheel support rolling bearing unit 1a of this example is a wheel support rolling bearing unit for a driven wheel of a general passenger car, and includes an outer ring 2, a hub 3, a plurality of rolling elements 4, 4, and a plurality of rolling bearing units. A bolt 29, a seal ring 16a, and a cover 27a are provided. Of these, the outer ring 2 is provided with double-row outer ring raceways 5a and 5b on the inner peripheral surface and a stationary flange 6 on the axially intermediate portion of the outer peripheral surface. Through holes 7 through which bolts for connecting and fixing the outer ring 2 to a suspension device are provided at a plurality of locations in the circumferential middle portion of the stationary flange 6.

  The hub 3 is a combination of a hub body 8 and an inner ring 9, and is arranged coaxially with the outer ring 2 on the radially inner side of the outer ring 2. The hub body 8 has a rotation-side flange 10 on the outer peripheral surface of the outer ring 2 that protrudes outward in the axial direction from the axial end of the outer ring 2, and the shaft of the double-row outer ring raceways 5 a and 5 b. The inner ring raceway 11a in the axially outer row is provided at the axially intermediate portion facing the outer ring raceway 5a in the outer side row, and the small-diameter step portion 12 is also provided at the inner end portion in the axial direction. And the screw hole 13 is provided in the circumferential direction several places of the radial direction intermediate part of the said rotation side flange 10. As shown in FIG. Such a rotation-side flange 10 can be provided radially on the outer peripheral surface of the hub main body 8, or can be provided on the outer peripheral surface of the hub main body 8 in the shape of a ring plate over the entire periphery. The inner ring 9 is provided with an inner ring raceway 11b in an inner row in the axial direction on the outer peripheral surface, and is fitted and fixed to the small-diameter step portion 12 by an interference fit. In this state, the inner end surface in the axial direction of the inner ring 9 protrudes inward in the axial direction from the inner end surface in the axial direction of the inner ring 9 in the cylindrical portion provided at the inner end portion in the axial direction of the hub body 8. The portion is restrained by a restraining portion (caulking portion) 39 formed by plastic deformation outward in the radial direction. An annular encoder 35 formed by fixing a permanent magnet to a magnetic metal material by bonding or the like is externally fitted and fixed to the outer peripheral surface of the inner end portion in the axial direction of the inner ring 9.

  Each of the rolling elements 4, 4 is held between the double row outer ring raceways 5a, 5b and the double row inner ring raceways 11a, 11b by the cages 14a, 14b. A plurality of rolls are provided for each roll. In the case of the illustrated example, balls are used as the rolling elements 4 and 4. However, in the case of a rolling bearing unit for supporting a wheel for an automobile that is heavy in weight, a tapered roller may be used instead of the ball. it can.

The bolts 29 rotate in the state where they are inserted from the outside in the axial direction through the mounting holes 32a and 32b provided in the wheel 30 constituting the wheel and the disc (or rotor) 31 which is a rotating body for braking. The screw hole 13 provided in the side flange 10 is screwed from the outside in the axial direction. With such a configuration, the wheel 30 and the disk 31 are coupled and fixed to the outer surface in the axial direction of the rotation side flange 10. In the case of this example, the front end surface of each bolt 29 is positioned outward in the axial direction from the inner surface in the axial direction of the rotation side flange 10. That is, the axial length of the screw portion of each bolt 29 is shorter than the axial length of the screw hole 13. Specifically, the dent amount L ₂₉ from the axially inner side surface of the rotation side flange 10 of the front end surface of each bolt 29 is set to 0.5 mm or more and 1.5 mm or less. When the dent L ₂₉ is less than 0.5 mm, the pressure change accompanying the change in the air flow when the tip surface of each bolt 29 passes cannot be made sufficiently large, and the external of the foreign matter as will be described later. There is a possibility that it will be difficult to obtain the effect of discharging into space. On the other hand, if the dent L ₂₉ is larger than 1.5 mm, a sufficient amount of screwing of the bolts 29 with respect to the screw holes 13 cannot be ensured, and the wheel 30 and the disk 31 with respect to the rotating side flange 10 are not secured. It becomes difficult to ensure sufficient support strength (support rigidity). However, the dent amount L ₂₉ can be appropriately changed according to the weight of the vehicle, the diameter (outer diameter) of the wheel and the brake rotating body, and the like.

  The seal ring 16a closes the axially outer end opening of the internal space 15 existing between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3, It consists of material 18a. Of these, the metal core 17a is made of a metal plate such as a mild steel plate, the fitting cylinder part 19a, and the annular ring part 20a bent radially outward from the axial outer end edge of the fitting cylinder part 19a, The fitting cylinder portion 19a includes a bent portion 21a that is folded back in a U shape from the inner edge in the axial direction toward the radially inner side and the axially outer side. Of these, the fitting tube portion 19a is fitted and fixed to the inner peripheral surface of the outer end portion 2 of the outer ring 2 by an interference fit, and the inner side surface of the annular portion 20a is fixed to the shaft of the outer ring 2. It abuts against the outer edge of the direction.

  The sealing material 18a is made of an elastic material such as an elastomer such as rubber, and is bonded and fixed to the cored bar 17a by vulcanization adhesion or the like. And a weir portion 26a. Each of the seal lips 22d and 22e is slidably contacted with the inner peripheral surface of the rotation side flange 10 or the outer peripheral surface of the intermediate portion of the hub 3 over the entire circumference.

Of the seal lips 22d and 22e, the flange lip 33 extends (inclined) further outward in the radial direction than the seal lip 22e provided on the outer side in the radial direction and outward in the radial direction toward the outer side in the axial direction. It is provided in the state to do. Then, the tip edge (axial outer edge) of the flange lip 33 is located on the tip side of each bolt 29 (the axis of the screw hole 13) in the axial inner surface of the rotary flange 10. In the direction inner end opening), a portion that is aligned (matched) with the inner end (the lower end in FIG. 2) in the radial direction of the hub 3 is made to face and oppose. Thereby, the labyrinth seal 25a is provided between the front end edge of the collar lip 33 and the axially inner side surface of the rotation side flange 10. Specifically, in a state where the hub 3 is not rotating, the tip edge of the collar lip 33 and the axial inner side surface of the rotary flange 10 (from the axial inner end opening of the screw hole 13). The distance (distance with respect to the axial direction) d _a between the portion and the portion deviated in the circumferential direction is 0.5 mm or more and 1.5 mm or less. In the case of this example, since the collar lip 33 is provided radially outward from the seal lips 22e, 22f, the wheel support rolling bearing unit 1a is operated (when the hub 3 is rotated). The distance d _a greatly fluctuates due to the action of the moment or the like. If this distance d _a is less than 0.5 mm, during operation of the wheel supporting rolling bearing unit 1a, the leading edge of the eaves lip 33 and the axial inner surface of the rotary side flange 10 may contact . On the other hand, when the distance d _a is greater than 1.5 mm, the can not be the distal end surface of each bolt 29 is sufficiently large pressure changes due to the change of the air flow as it passes through, such as will be described later, the foreign matter There is a possibility that it will be difficult to obtain a sufficient discharge effect to the outside space. However, the distance d _a can be appropriately changed in accordance with the axial dimensions of the wheel supporting rolling bearing unit 1a. The inner peripheral surface of the front half of the collar lip 33 and the stepped portion 24 provided on the proximal end portion (radially inward portion) of the axially inner side surface of the rotation side flange 10 are closely opposed to each other, The entire length of the labyrinth seal 25a can be secured.

  The weir portion 26a protrudes radially outward from the axially outer end portion of the outer ring 2 by a portion of the sealing material 18a that continues radially outward from the base end portion of the collar lip 33. It is provided in the state. Such a dam portion 26a prevents moisture adhering to the outer peripheral surface of the outer ring 2 from entering the inner space 15 through the outer peripheral surface of the outer ring 2 (damping). .

  The cover 27a is made of a non-magnetic material in a bottomed cylindrical shape, and the cylindrical portion is fitted and fixed to the inner end in the axial direction of the outer ring 2 to fix the inner space 15. The axial inner end opening is closed. However, the axially inner end opening of the internal space 15 can be closed by the combination seal ring 28 as in the conventional structure shown in FIG.

According to the wheel support rolling bearing unit 1a of the present example as described above, the effect of preventing foreign matter from entering the internal space 15 in which the rolling elements 4 and 4 are installed is ensured while ensuring the degree of freedom of design. It can be improved further.
Of these, the degree of freedom in design can be ensured for the same reason as the conventional structure shown in FIG. That is, the wheel support rolling bearing unit 1a of the present example is configured so that the wheel 30 and the disk 31 are supported and fixed to the outer surface in the axial direction of the rotation side flange 10, and the mounting holes 32a of the wheel 30 and the disk 31 are provided. Each bolt 29 inserted through 32b is screwed into the screw hole 13 of the rotation side flange 10 from the outside in the axial direction. Therefore, as in the conventional structure, the tip end portion of each bolt 29 does not protrude from the axial inner surface of the rotation side flange 10, and the outer diameter of the axial outer end portion of the outer ring 2 is set to It can be made larger than the structure described in Patent Document 1 in which the head is positioned on the inner side in the axial direction of the rotation side flange. In short, according to the wheel bearing rolling bearing unit 1a, the degree of freedom in design can be improved as compared with the structure described in Patent Document 1, and the track diameter of the outer ring raceway 5a in the axially outer row ( As a result, the pitch circle diameter of the rolling elements 4 and 4 in the axially outer row can be increased, and the rolling fatigue life and moment rigidity can be improved. Furthermore, in the case of this example, it is not necessary to provide a seating surface for contacting the axially outer surface of the head portion of the stud on the axially inner surface of the rotating flange 10. The axial thickness of the intermediate portion in the direction can be increased, and the strength and rigidity of the rotation side flange 10 can be improved.

  Further, when the rotation side flange 10 rotates with the rotation of the hub 3 during the operation of the wheel support rolling bearing unit 1a, the axial inner surface of the rotation side flange 10 (and the rotation side flange 10). An air flow is generated between the front end surface of each bolt 29 that is supported and fixed and the front end edge of the collar lip 33. Due to this air flow, foreign matter adhering to the surface of the heel lip 33, such as being flipped up when the vehicle is running, is attracted to the rotating flange 10 side. In the case of this example, the front end surface of each bolt 29 is positioned outward in the axial direction from the axial inner surface of the rotation side flange 10. For this reason, when the tip surface of each bolt 29 passes the tip edge of the collar lip 33, the velocity of the airflow is between the tip surface of each bolt 29 and the tip edge of the collar lip 33. It becomes smaller (slower) and the pressure becomes larger. Accordingly, the foreign matter attracted to the rotating flange 10 side is discharged toward the tip surface of each bolt 29 by the action of the airflow and pressure (approached to the part), and then the action of centrifugal force. Is discharged into the external space. As a result, the effect of preventing the entry of foreign matter into the internal space 15 can be improved over the conventional structure shown in FIG.

  When the present invention is carried out, the seal ring that closes the axially outer end opening of the internal space 15 is formed by bending a metal plate into a substantially L shape, and the fitting tube portion of the metal core is formed on the outer ring. The outer circumferential surface of the outer ring portion is fitted and fixed to the outer peripheral surface of the outer end portion of the axial direction, and the inner side surface in the axial direction of the circular ring portion bent radially inward from the outer edge in the axial direction of the fitting cylindrical portion is axially outer of the outer ring. A structure that abuts against the end face can also be used.

Further, the wheel bearing rolling bearing unit of the present invention is provided with an engagement hole such as a spline hole for engaging the drive shaft constituting the constant velocity joint so that power can be transmitted at the center of the hub. Either a structure for a driving wheel or a structure for a driven wheel having a solid hub can be implemented.
Further, the present invention is not limited to the structure in which the pitch circle diameters of the rolling elements in both rows are equal, but the pitch circle diameters of the rolling elements in both rows are different from each other (the pitch circle diameters of the rolling elements in the axially outer row are different from each other in the axial direction). It is also possible to apply to a so-called different diameter PCD type wheel support rolling bearing unit (which is larger or smaller than the pitch circle diameter of the inner row).

[Second Example of Embodiment]
FIG. 3 shows a second example of the embodiment of the present invention. The wheel support rolling bearing unit 1b of the present example has a bottom having a recess recessed outward in the axial direction at the center of the front end surface of a plurality of bolts 29a for coupling and fixing the wheel 30 and the disk 31 to the rotation side flange 10. A cylindrical recess 36 is provided. The axial position of such a portion near the outer diameter of the front end surface of the bolt 29a (the outer portion in the radial direction of each bolt 29a, the portion removed from the recess 36) is defined as the axial direction of the rotating flange 10. It is made to substantially coincide with the axial position of the inner surface. Therefore, in the case of this example, among the front end surfaces of the bolts 29 a, the bottom surface of the recess 36 is positioned axially outward from the axial inner surface of the rotation side flange 10. The leading edge of the collar lip 33a of the seal ring 16a that closes the axially outer end opening of the internal space 15 is located on the rotational side flange 10 at the radial position on the axially inner side surface of the rotational side flange 10. It is made to face and oppose to the part (it is matched) of the recessed part 36 (among the inner side part regarding the radial direction of the hub 3) provided in the front end surface of each said bolt 29a supported and fixed to. In the case of this example, the collar lip 33a is provided so as to extend in the axial direction, and the outer peripheral surface of the collar lip 33a is a cylindrical surface centered on the central axis of the hub 3.

In the case of this example, when the recessed portion 36 passes through the distal end edge of the flange lip 33a, the portion (the recessed portion 36 and the flange lip 33a At the portion between the front end edge), the velocity of the airflow generated with the rotation of the hub 3 decreases, and the pressure also increases. Then, after the foreign matter attracted to the rotating flange 10 side is discharged toward the concave portion 36 by the action of the air flow and pressure, it is discharged to the external space by the action of centrifugal force. In the case of this example, the radial positions of the outer lip 33a and the outer end of the outer ring 2 in the axial direction are set to the wheel support rolling of the first example of the embodiment shown in FIGS. Compared with the bearing unit 1a, it can be made radially outward.
The structure and operation of the other parts are the same as in the first example of the above embodiment.

[Third example of embodiment]
FIG. 4 shows a third example of the embodiment of the present invention. In the case of the wheel support rolling bearing unit 1c of the present example, the thick wall portion 37 provided in the radially inner half portion of the rotating side flange is formed in the radially intermediate portion of the rotating side flange 10a in the axial direction inner surface. A stepped portion 24a is provided which is continuous with the thin portion 38 provided in the radially outer half. Of the axially inner end opening of the screw hole 13a for screwing a plurality of bolts 29b for coupling and fixing the wheel 30 and the disk 31 to the rotation side flange 10a, an inner portion in the radial direction of the hub 3 is formed. The step 24a is opened. And in the state which screwed each said bolt 29b in the said screw hole 13a, the axial direction position of the radial direction outer half part (outer half part regarding the radial direction of the said hub 3) of the front end surfaces of these each bolt 29b is set. , And the axially inner side surface of the thin portion 38 constituting the rotating side flange 10 (the axial position of the portion existing around the radially outer half of the front end surface of each bolt 29b). Therefore, in the case of this example, the inner part of the front end face of each bolt 29b in the radial direction of the hub 3 (the part aligned with the stepped part 24a) is the inner side in the axial direction of the rotary flange 10a. Among the side surfaces, the step portion 24a and the portion existing radially inward from the step portion 24a are positioned outward in the axial direction. The leading edge of the collar lip 33 of the seal ring 16a that closes the axially outer end opening of the internal space 15 is made to face the inner part of the distal end surface of each bolt 29b in the radial direction of the hub 3. The stepped portion 24a is placed close to and opposed to the stepped portion 24a.

In the case of this example, when the inner portion of the front end surface of each bolt 29b in the radial direction of the hub 3 passes through the front end edge of the collar lip 33, the bolt 29a The speed of the air flow generated by the rotation of the hub 3 is reduced and the pressure is increased between the inner surface of the front end surface in the radial direction of the hub 3 and the front end edge of the collar lip 33. Become. After the foreign matter attracted to the rotating flange 10 side by the action of the airflow and pressure is discharged toward the inner portion of the front end surface of each bolt 29b in the radial direction of the hub 3. It is discharged to the external space by the action of centrifugal force.
The configuration and operation of the other parts are the same as in the first example of the embodiment described above.

DESCRIPTION OF SYMBOLS 1, 1a-1c Rolling bearing unit for wheel support 2 Outer ring 3 Hub 4 Rolling body 5a, 5b Outer ring raceway 6 Stationary side flange 7 Through hole 8 Hub body 9 Inner ring 10, 10a Rotation side flange 11a, 11b Inner ring raceway 12 Small diameter step part 13, 13a Screw hole 14a, 14b Cage 15 Internal space 16, 16a Seal ring 17, 17a Core metal 18, 18a Sealing material 19, 19a Fitting cylinder part 20, 20a Ring part 21, 21a Bent part 22a-22e Seal Lip 23 Labyrinth slip 24, 24a Step 25, 25a Labyrinth seal 26, 26a Weir 27, 27a Cover 28 Combination seal ring 29, 29a, 29b Bolt 30 Wheel 31 Disc 32a, 32b Mounting hole 33 ３３ Lip 34 Spline hole 35 Encoder 36 concave 37 thick portion 38 thin portion 39 pressing section

Claims (1)

An outer ring that is supported by a suspension device in use and does not rotate, a hub disposed coaxially with the outer ring on the radially inner side of the outer ring, a plurality of rolling elements, a plurality of bolts, and a seal ring ,
The outer ring has a double row outer ring raceway on the inner peripheral surface,
The hub protrudes outward in the axial direction from the outer end in the axial direction of the outer ring on the outer peripheral surface, and the inner ring raceway in the double row provided on a portion of the outer peripheral surface facing the double-row outer ring raceway. And a rotation side flange provided with screw holes at a plurality of locations in the circumferential direction of the radial intermediate portion,
Each of the rolling elements is provided between the double row outer ring raceway and the double row inner ring raceway so as to be freely rollable for each row,
Each of the bolts is for fixing a wheel and a braking rotator to the rotation-side flange, and is screwed into the screw hole in a state in which a front end surface faces inward in the axial direction,
The seal ring closes an axially outer end opening of an inner space existing between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub, and is fixed to the axially outer end portion of the outer ring. And a sealing material made of an elastic material reinforced by the core metal, and the sealing material slidably contacts the entire inner surface of the axial side surface of the rotating flange or the outer peripheral surface of the hub. In a rolling bearing unit for supporting a wheel, comprising a seal lip and a collar lip provided radially outward from the seal lip and having a leading edge closely adjacent to the axial inner surface of the rotary flange. And
At least a part of the front end surface of each bolt is positioned axially outward from the axially inner surface of the rotating flange;
The front edge of the flange lip is aligned with the portion of the front end surface of each bolt that is positioned axially outward from the axial inner surface of the rotary flange. Rolling bearing unit for wheel support, characterized by being close to and facing the inner surface in the axial direction.

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