WO2017033653A1

WO2017033653A1 - Rolling bearing unit for wheel support

Info

Publication number: WO2017033653A1
Application number: PCT/JP2016/071861
Authority: WO
Inventors: 真之田辺; 将充渡部
Original assignee: 日本精工株式会社
Priority date: 2015-08-26
Filing date: 2016-07-26
Publication date: 2017-03-02

Abstract

A rotary-side flange is provided with a foreign body discharge hole that opens to at least an axial inner side face of the two axial side faces of the rotary-side flange. The outer diameter of an external end face of an outer ring in the axial direction is larger than the diameter of an inscribed circle of the inner end of the foreign body discharge hole in the radial direction with the central axis of a hub serving as the center.

Description

Rolling bearing unit for wheel support

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

FIG. 11 shows a conventional structure described in Patent Document 1 as a wheel-supporting rolling bearing unit (hereinafter simply referred to as a bearing unit) for rotatably supporting a wheel with respect to an automobile suspension system. An example is shown. The bearing unit 1 rotatably supports the hub 3 on the inner diameter side of the outer ring 2 via a plurality of

balls

4 and 4.

The outer ring 2 is made of medium carbon steel. The inner peripheral surface of the outer ring 2 has double-row

outer ring raceways

5a and 5b. The outer peripheral surface of the outer ring 2 has a stationary side flange 6. Screw holes 7 are provided at a plurality of locations in the circumferential direction of the stationary flange 6. The outer ring 2 does not rotate because the outer ring 2 is coupled and fixed to the knuckle constituting the suspension device by the bolt screwed into the screw hole 7.

The outer peripheral surface of the hub 3 has double-row

inner ring raceways

8 a and 8 b and a rotation side flange 9. In use, the hub 3 rotates with a wheel coupled and fixed to the rotation side flange 9. In addition, mounting holes 11 that penetrate the rotation side flange 9 in the axial direction are provided at a plurality of locations in the circumferential direction of the rotation side flange 9. The base end portions of a plurality of studs 12 each having a serration portion are press-fitted into each mounting hole 11. Thereby, it is possible to support and fix a braking rotating body such as a disk rotor and a drum brake and a wheel constituting the wheel on the rotation side flange 9. Further, a through hole 13 is provided in a portion of the rotation side flange 9 between the mounting holes 11 adjacent in the circumferential direction. By providing each through hole 13, the hub 3 is reduced in weight, and the entire bearing unit 1 is reduced in weight. In addition, each through hole 13 is tightened with a bolt screwed into the screw hole 7 of the stationary-side flange 6 (or inserted into the through-hole), and is attached to a suspension device for components constituting the braking device. Etc. can be inserted. In order to reduce the moment of inertia of the hub 3 and improve the driving performance and fuel consumption performance centering on the acceleration performance, the through-hole 13 should be provided as close to the outer diameter portion of the rotation side flange 9 as possible. Is preferred. For this reason, in the case of the illustrated example, the diameter D ₁₃ of the inscribed circle at the radially inner end of each through hole 13 centering on the central axis of the bearing unit 1 is set to the outer diameter of the axially outer end of the outer ring 2. It is set to be larger than D _2.

The hub 3 is formed by connecting and fixing a hub body 14 and an inner ring 15. The hub body 14 is made of medium carbon steel. A portion near the outer end of the hub body 14 in the axial direction ("outside" in relation to the axial direction is the outer side in the width direction of the vehicle when assembled to the automobile, and is the left side in FIGS. 1 to 5 and 7 to 11. “Inside” is the center side in the width direction of the vehicle, and is the right side of FIGS. 1 to 5 and 7 to 11). The inner ring raceway 8a in the axially outer row of the double row

inner ring raceways

8a and 8b is directly provided on the outer circumferential surface of the hub body 14 in the axial direction intermediate portion.

The inner ring 15 is made of bearing steel. On the outer peripheral surface of the inner ring 15, the inner ring raceway 8 b in the axially inner row of the double row

inner ring raceways

8 a and 8 b is provided. The inner ring 15 is externally fitted and fixed to a small-diameter step portion 16 provided near the axially inner end of the hub body 14. The inner end surface in the axial direction of the inner ring 15 is held down by a caulking portion 17 provided at the inner end portion in the axial direction of the hub body 14. Thus, the inner ring 15 is fixedly coupled to the hub body 14.

Each

ball

4, 4 is made of bearing steel or ceramic. A plurality of balls 4 are freely rollable in each row while being held by

cages

10 and 10 between double row

outer ring raceways

5a and 5b and double row

inner ring raceways

8a and 8b. Is provided.

Further, the gap between the inner peripheral surface of the outer end portion of the outer ring 2 in the axial direction and the outer peripheral surface of the intermediate portion of the hub 3 in the axial direction is closed by a seal ring 18 having three seal lips. The tip ends of the three seal lips of the seal ring 18 are in sliding contact with the inner circumferential surface of the rotation side flange 9 or the outer circumferential surface of the hub 3 in the axial direction at the entire circumference. In this way, the seal ring 18 closes the opening on the axially outer end side of the rolling element installation space 19 in which the

balls

4 and 4 are installed.

In the case of the illustrated example, the bearing unit 1 has different pitch circle diameters (PCD) of the balls in both rows in order to ensure a large moment rigidity while suppressing an increase in size. That is, the pitch circle diameter of the

balls

4, 4 in the axially outer row is made larger than the pitch circle diameter of the

balls

4, 4 in the axially inner row. For this purpose, the inner ring raceway 5a in the axially outer row is made larger than the inner diameter of the outer ring raceway 5b in the axially outer row and the inner ring raceway 5a in the axially outer row is made larger. It is larger than the outer diameter of 8b.

In the case of the conventional structure as described above, if the use conditions become severe, the seal ring 18 attached to the opening on the axially outer end side of the rolling element installation space 19 may not necessarily exhibit sufficient sealing performance. In other words, a gap is provided between the outer end surface in the axial direction of the outer ring 2 and the inner surface in the axial direction of the rotation side flange 9 in order to prevent these two surfaces from contacting each other (metal contact). Then, when traveling on a rough road such as a gravel road, foreign matters such as relatively large sand particles enter through this gap, and this foreign matter slides between the seal lip constituting the seal ring 18 and the axially inner side surface of the rotation side flange 9. If it enters the contact portion, the sliding contact portion may be damaged such as abnormal wear.

Japanese Laid-Open Patent Publication No. 2007-1000071

In view of the circumstances as described above, the present invention provides a wheel support rolling device that can easily discharge foreign matter that has entered through a gap between an axial outer end surface of an outer ring and an axial inner surface of a rotary flange into an external space. Invented to realize the structure of the bearing unit.

The wheel support rolling bearing unit of the present disclosure includes an outer ring, a hub, and a plurality of rolling elements.
The outer ring has a double-row outer ring raceway on the inner circumferential surface, and is supported by the suspension device in a use state and does not rotate.
The hub is disposed coaxially with the outer ring on the inner diameter side of the outer ring, has a double-row inner ring raceway on a portion of the outer peripheral surface facing the double-row outer ring raceway, and an axially outer end portion of the outer ring. In addition, a rotation-side flange for coupling and fixing the braking rotator and the wheel is provided at a portion protruding outward in the axial direction.
A plurality of rolling elements are provided between the outer ring raceway in the double row and the inner ring raceway in the double row so as to be freely rollable for each row.
Foreign matter discharge holes (through holes opened on both sides in the axial direction of the rotation side flange) that are opened in at least the inner side surface in the axial direction of both sides in the axial direction of the rotation side flange in one or more circumferential directions of the rotation side flange Or a bottomed hole opened only on the inner side surface in the axial direction is provided.
The outer diameter of the outer end surface in the axial direction of the outer ring is larger than the diameter of the inscribed circle at the inner end in the radial direction of the foreign matter discharge hole centered on the central axis of the hub (the central axis of the wheel bearing rolling bearing unit). large.
Such foreign matter discharge holes are used, for example, to reduce the weight of the hub, to support the outer ring on the suspension device, or to attach a component constituting a braking device to the suspension device. It is provided to insert a tool.

When implementing the rolling bearing unit for supporting a wheel according to the present disclosure as described above, a labyrinth seal is preferably provided between the axially outer end surface of the outer ring and the axially inner side surface of the rotating side flange that face each other. .
Specifically, such a labyrinth seal is configured as follows, for example.
That is, the outer ring side step portion having an inner diameter larger than the portion adjacent to the inner side in the axial direction is provided at the outer end portion in the axial direction of the inner peripheral surface of the outer ring. Further, on the inner side surface in the axial direction of the rotation side flange, a thick portion provided at a portion near the base end (base portion) of the rotation side flange, and a thickness (axial thickness) than the thick portion. And a thin step portion that is continuous with each other. A notch portion having a crank-shaped cross section is provided at the axially inner end portion of the step portion, and a flange-side step portion having a smaller outer diameter than the portion adjacent to the outside in the axial direction is provided. An axial labyrinth seal is provided between the outer ring side step portion and the flange side step portion by causing the outer ring side step portion and the flange side step portion to face each other in the radial direction. At the same time, the outer end surface in the axial direction of the outer ring and the inner end surface of the step portion on the flange side (the step surface bent at a right angle radially outward from the outer end portion in the axial direction of the flange side step portion) are closely opposed to each other. Thus, a radial labyrinth seal is provided between the axially outer end surface of the outer ring and the inner end surface of the flange-side stepped portion.

When implementing the wheel support rolling bearing unit of the present disclosure as described above, the inner peripheral surface of the foreign matter discharge hole is preferably a cylindrical surface whose inner diameter does not change in the axial direction. That is, the foreign matter discharge hole is preferably a cylindrical hole. However, the inner peripheral surface of the foreign matter discharge hole may be a conical surface inclined in a direction in which the inner diameter becomes smaller toward the outer side in the axial direction. That is, the foreign matter discharge hole can be a conical hole. In any case, it is preferable that the inner peripheral surface of the foreign matter discharge hole is a smooth surface whose inner diameter does not repeatedly change in the axial direction.

Further, when the wheel support rolling bearing unit of the present disclosure as described above is implemented, preferably, outer ring side recesses are provided in one or more circumferential directions of the outer ring. The outer ring side recess opens to the outer circumferential surface and the outer circumferential surface of the outer ring in the axial direction.
Such an outer ring side recess is preferably provided at a lower portion (lower half) in a state where the wheel bearing rolling bearing unit is supported by a vehicle suspension device, and more preferably at the lower end.

According to the wheel support rolling bearing unit of the present disclosure as described above, foreign matter that has entered from the gap between the outer end surface in the axial direction of the outer ring and the inner surface in the axial direction of the rotation side flange can be easily discharged to the external space.
In other words, if foreign matter bounced up when the vehicle travels enters between the outer end surface in the axial direction of the outer ring and the inner side surface in the axial direction of the rotation side flange, the foreign matter will move along the axis of the outer ring along with the rotation of the rotation side flange. As is apparent from Bernoulli's theorem, the air flow generated between the outer end surface in the direction and the inner side surface in the axial direction of the rotating flange attracts the rotating flange at a higher speed and lower pressure.
The diameter of the inscribed circle at the radially inner end of the foreign matter discharge hole centered on the central axis of the hub is also made smaller near the outer diameter of the outer end surface in the axial direction of the outer ring, so that the portion near the inner diameter of the foreign matter discharge hole and the outer ring The outer end face in the axial direction is made to face. At the portion where the outer diameter portion of the foreign matter discharge hole and the outer end surface in the axial direction of the outer ring face each other, the speed of the airflow is reduced (slow), and the space between the outer end surface in the axial direction of the outer ring and the inner side surface in the axial direction of the rotary flange The pressure in the gap also increases. Accordingly, the foreign matter drawn toward the rotation side flange is discharged into the foreign matter discharge hole by the action of airflow and pressure (drawn toward the foreign matter discharge hole side). Then, it is discharged to the external space by the action of centrifugal force. As a result, foreign matter can be prevented from entering the rolling element installation space existing between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub, and the durability of the wheel bearing rolling bearing unit can be improved. Can do.

Sectional drawing which shows the 1st example of embodiment of this invention. The X section enlarged view of FIG. FIG. 2 is a schematic diagram corresponding to the YY cross section of FIG. 1, showing a state in which a braking rotator is supported and fixed to a rotation side flange. The figure corresponding to FIG. 2 which shows the 2nd example of embodiment of this invention. The figure equivalent to FIG. 2 which shows the 3rd example of embodiment of this invention. FIG. 6 is a ZZ sectional view of FIG. 5. The figure equivalent to FIG. 2 which shows the 4th example of embodiment of this invention. The principal part expanded sectional view for demonstrating the method of providing a large diameter part. The figure equivalent to FIG. 2 which shows the 5th example of embodiment of this invention. The principal part expanded sectional view for demonstrating the method of providing a recessed part. Sectional drawing which shows an example of a conventional structure.

[First Example of Embodiment]
1 to 3 show a first example of an embodiment of the present invention. A wheel-supporting rolling bearing unit 1a (hereinafter, simply referred to as a bearing unit) of this example includes an outer ring 2a, a hub 3a, and a plurality of

balls

4a and 4b, each of which is a rolling element. .

Double row

outer ring raceways

5c and 5d are provided on the inner peripheral surface of the outer ring 2a. A stationary side flange 6 is provided at the axially intermediate portion of the outer peripheral surface of the outer ring 2a. Among the double row

outer ring raceways

5c and 5d, the inner diameter of the outer ring raceway 5c in the outer row in the axial direction is larger than the inner diameter of the outer ring raceway 5d in the inner row in the axial direction. For this reason, the inner circumference of the inner circumferential surface of the outer ring 2a inclined toward the axially outer side of the outer ring raceway 5d in the axially inner row is inclined so that the inner diameter becomes smaller toward the inner side in the axial direction. The surface side step part 20 is provided. In addition, through holes 36 are provided at a plurality of locations in the circumferential direction of the stationary flange 6. A bolt (not shown) for inserting and fixing the outer ring 2 a to a knuckle constituting the suspension device is inserted into the through hole 36.

The hub 3a is a combination of the hub body 14a and the inner ring 15. Near the outer end of the hub 3a in the axial direction, a braking rotator 35 (see FIG. 3) such as a rotor or a drum and a rotation side flange 9a for supporting a wheel are provided. Double-row

inner ring raceways

8c and 8d are provided at the axially intermediate portion and inner end portion of the outer peripheral surface of the hub 3a. Of the double row

inner ring raceways

8c and 8d, the outer diameter of the inner ring raceway 8c in the axially outer row is larger than the outer diameter of the inner ring raceway 8d in the axially inner row.

In addition, mounting holes 11 are provided at a plurality of locations in the circumferential direction of the rotation side flange 9a. The base end portion of the stud 12 that supports and fixes the brake rotating body 35 and the wheel is press-fitted into the mounting hole 11 in the rotation side flange 9a. And the through-hole 13a which is a foreign material discharge | emission hole is provided in at least one place of the part between the attachment holes 11 adjacent to the circumference direction among the rotation side flanges 9a. The through hole 13a penetrates the rotation side flange 9a in the axial direction. That is, the through-hole 13a opens on both axial sides of the rotation side flange 9a.

In the case of this example, the radially inward portion of each through hole 13a is opposed to the axially outer end surface of the outer ring 2a. That is, as shown in FIG. 2, the diameter D _13a of the inscribed circle of the radially inner end of each through hole 13a around the center axis of the bearing unit 1a, the outer diameter D of the axially outer end face of the outer ring 2a _It is smaller than _2a ( _D13a < _D2a ). The inner diameter of each through hole 13a, and, {difference between the outer diameter _{D 2a} and the diameter _{_{_{D 13a (= D 2a -D 13a}}} )} amount larger than the diameter _{D 13a} of the outer diameter _{D 2a} is The brake rotating body 35 supported and fixed to the rotation side flange 9a and the size (outer diameter), weight, etc. of the wheel are set as appropriate. For example, in the case of a general automobile bearing unit, the inner diameter of each through hole 13a is about 20 to 30 mm, and the difference (= D _2a −D _13a ) between the outer diameter D _2a and the diameter D _13a is 1 About 8 mm. In the case of this example, each through hole 13a is a cylindrical hole (circular hole) in which the inner diameter of the inner peripheral surface does not change in the axial direction.

In order to make the outer diameters of the double-row

inner ring raceways

8c and 8d different, the outer diameter of the outer peripheral surface of the hub body 14a is slightly closer to the inner side in the axial direction than the inner ring raceway 8c in the axially outer row. An outer peripheral surface side stepped portion 21 is provided to connect an axially inner portion with a small outer diameter and an axially outer portion with a large outer diameter. Further, a small-diameter step portion 16 is provided on the outer peripheral surface of the hub body 14a at a portion closer to the inner end in the axial direction that is closer to the inner side in the axial direction than the step portion 21 on the outer peripheral surface side. An inner ring 15 having an inner ring raceway 8d in the axially inner row provided on the outer peripheral surface is externally fitted to the small diameter step portion 16. The inner ring 15 is pressed against the stepped surface 22 existing at the axially outer end of the small-diameter stepped portion 16 by a caulking portion 17 provided at the axially inner end of the hub body 14a. In this state, the inner ring 15 is coupled and fixed to the hub body 14a.

Each

ball

4a, 4b is held in the

cages

10a, 10b between the double row

outer ring raceways

5c, 5d and the double row

inner ring raceways

8c, 8d. It is provided so that it can roll freely. In this state, each

ball

4a, 4b arranged in a double row is provided with a contact angle of the rear combination type together with the preload. The pitch circle diameters of the

balls

4a and 4b in each row differ from each other in accordance with the difference in inner diameter between the double row

outer ring raceways

5c and 5d and the difference in outer diameter between the double row

inner ring raceways

8c and 8d. That is, the pitch circle diameters of the

balls

4a, 4a in the axially outer row are larger than the pitch circle diameters of the

balls

4b, 4b in the axially inner row. In the case of this example, the diameters of the

balls

4a and 4a in the axially outer row are made smaller than the diameters of the

balls

4b and 4b in the axially inner row. However, the diameters of the

balls

4a, 4a in the axially outer row and the diameters of the

balls

4b, 4b in the axially inner row can be made equal to each other. Further, in the case of a bearing unit that increases in weight, a tapered roller can be used instead of a ball for one or both of the two rows.

In the case of this example, a rolling element installation space 19 exists between the inner peripheral surface of the outer ring 2a and the outer peripheral surface of the hub 3a, and the

balls

4a and 4b are installed in the rolling element installation space. The axially outer end opening of the rolling element installation space 19 is closed by a seal ring 18 attached to the opening. That is, the three seal lips constituting the seal ring 18 are respectively slidably contacted with the outer peripheral surface of the intermediate portion in the axial direction of the hub body 14a and the inner surface in the axial direction of the rotation side flange 9a over the entire periphery. Yes. Also, the inner end opening in the axial direction of the outer ring 2a is closed by a cover 23 that is mounted on the opening and is formed of a non-magnetic material and has a bottomed cylindrical shape. An encoder 24 is fitted and fixed to the outer peripheral surface of the inner end portion in the axial direction of the inner ring 15. That is, the rotational speed of the wheel coupled and fixed to the hub 3a can be detected by making a speed sensor (not shown) face the detected surface of the encoder 24 via the cover 23.

Furthermore, in the case of this example, a labyrinth seal 25 is provided between the axially outer end surface of the outer ring 2a and the axially inner surface of the rotation side flange 9a. The labyrinth seal 25 includes a radial labyrinth seal 32, which will be described later, and an axial labyrinth seal 31 that is bent inward in the axial direction from the radial inner end of the radial labyrinth seal 32 as a whole. The cross section is substantially L-shaped.

An outer ring-side stepped portion 26 having a larger inner diameter than the portion adjacent to the inner side in the axial direction (the portion where the seal ring 18 is fitted and fixed) is provided on the inner peripheral surface of the outer ring 2a in the axial direction.

Further, on the inner side surface in the axial direction of the rotation side flange 9a, a thicker portion 27 provided in a portion near the base end (root portion) of the rotation side flange 9a and a thickness (axial thickness) than the thick portion 27. A thin step portion 28 is provided, and a step portion 29 is provided. The step surface shape of the step portion 29 is an arc shape or a substantially arc shape. A notch portion having a crank-shaped cross section is provided at the axially inner end portion of the step portion 29, and a flange-side step portion 30 having a smaller outer diameter than the portion adjacent to the outside in the axial direction is provided.

An axial labyrinth seal 31 is provided between the outer ring side step part 26 and the flange side step part 30 by causing the outer ring side step part 26 and the flange side step part 30 to face each other in the radial direction.

At the same time, the axially outer end surface of the outer ring 2a and the stepped surface bent at a right angle radially outward from the axially outer end of the flange-side stepped portion 30 are close to each other in the axial direction so that the outer ring 2a A radial labyrinth seal 32 is provided between the axially outer end surface and the stepped surface present at the axially outer end of the flange-side stepped portion 30. That is, by providing the radial labyrinth seal 32 at a position that does not overlap the seal ring 18 in the radial direction (a position that is separated from the seal ring 18 with respect to the axial direction), foreign matter such as muddy water splashed when the vehicle travels is removed. In the radial labyrinth seal 32, it is prevented from entering the radial labyrinth seal 32 and passing through the radial labyrinth seal 32 and reaching the seal ring 18 directly. In other words, the seal ring 18 is disposed radially inward and axially inward of the labyrinth seal 25, and the seal ring 18 is protected by the labyrinth seal 25.

The width (the radial width of the axial labyrinth seal 31 and the axial width of the radial labyrinth seal 32) and the length (length of the axial labyrinth seal 31) of the labyrinth seal 25 whose cross-sectional shape is L-shaped. The sum of the axial length and the radial length of the radial labyrinth seal 32) varies depending on the size and weight of the braking rotator 35 and the wheels supported and fixed to the rotation-side flange 9a.

For example, in the case of a general automobile bearing unit, the radial width W ₃₁ of the axial labyrinth seal 31 is preferably 0.5 to 1.0 mm, more preferably 0.55 to 0.8 mm, and still more preferably. Is 0.57 to 0.8 mm, and the axial length L ₃₁ of the labyrinth seal 31 in the axial direction is preferably 0.6 mm to 1.4 mm, more preferably 0.7 to 1.3 mm. On the other hand, the axial width W ₃₂ of the radial labyrinth seal 32 is preferably 0.8 to 1.5 mm, more preferably 0.9 to 1.3 mm, and the radial length L of the radial labyrinth seal 32 is set. ₃₂ is preferably 1.5 to 2.6 mm, more preferably 1.9 to 2.5 mm, and still more preferably 1.85 to 2.43 mm.

When the radial width W ₃₁ of the axial labyrinth seal 31 is smaller than 0.5 mm, or when the axial width W ₃₂ of the radial labyrinth seal 32 is smaller than 0.8 mm, the wheel rides on the curb, etc. In addition, there is a possibility that the axially outer end portion of the outer ring 2a and the rotation side flange 9a come into contact (collision). On the other hand, when the radial width W ₃₁ of the axial labyrinth seal 31 is made larger than 1.0 mm or the axial width W ₃₂ of the radial labyrinth seal 32 is made larger than 1.5 mm, foreign matter intrusion by the labyrinth seal 25 occurs. The prevention effect may not be obtained sufficiently. Also, or less than 0.6mm and the axial length _{L 31} in the axial direction of the labyrinth seal 31, when the radial length _{L 32} of the radial labyrinth seal 32 is smaller than 1.5 mm, the labyrinth seal 25 There is a possibility that the effect of preventing foreign matter intrusion due to is not sufficiently obtained. On the other hand, if greater than 1.4mm and the axial length _{L 31} in the axial direction of the labyrinth seal 31, when the radial length _{L 32} of the radial labyrinth seal 32 is greater than 2.6 mm, the bearing unit 1a is There is a possibility of increasing the size and weight.

However, in any of the labyrinth seals of the axial labyrinth seal 31 and the radial labyrinth seal 32, the length is made larger than the width (L ₃₁ > W ₃₁ , L ₃₂ > W ₃₂ ), and the labyrinth effect is obtained. It is increasing. Further, the length and width of the radial labyrinth seal 32 are made larger than the length and width of the axial labyrinth seal 31 (L ₃₁ > L ₃₂ , W ₃₁ > W ₃₂ ), and the labyrinth seal 25 is placed in the labyrinth seal 25. The invading foreign matter is kept in the radial labyrinth seal 32 as much as possible. As a result, as will be described later, foreign substances that have entered the labyrinth seal 25 are easily discharged into the external space by the presence of each through-hole 13a and the action of an air flow accompanying the rotation of the rotation-side flange 9a. The axial labyrinth seal 31 has a constant radial width W ₃₁ in the axial direction. Similarly, the radial labyrinth seal 32 has a constant axial width W ₃₂ in the radial direction.

According to the bearing unit 1a of the present example as described above, the effect of preventing foreign matter from entering the rolling element installation space 19 can be maintained well over a long period of time, and the durability can be further improved. That is, in this example, from the radial inner end of the radial labyrinth seal 32 and the radial labyrinth seal 32 between the axial outer end surface of the outer ring 2a and the axial inner surface of the rotation side flange 9a. A labyrinth seal 25 including an axial labyrinth seal 31 bent inward in the axial direction is provided. For this reason, it is difficult for the foreign matter jumped up when the vehicle equipped with the bearing unit 1 a travels to reach the portion where the tip edge of the seal lip constituting the seal ring 18 is in contact. That is, the seal ring 18 can be protected.

Even if foreign matter enters the labyrinth seal 25 (axial labyrinth seal 31), the foreign matter is caused by the labyrinth seal 25 (radial labyrinth seal 32) as the rotary flange 9a rotates. ), The air flow generated in the cylinder 9 is pulled toward the rotating flange 9a where the speed is high and the pressure is low, as is clear from Bernoulli's theorem.

Here, the diameter D _13a of the inscribed circle of the radially inner end of each through hole 13a around the center axis of the bearing unit 1a, smaller than the outer diameter D _2a of the axial outer end surface of the outer ring 2a (D _13a <D _2a ), the portion closer to the inner diameter of each through hole 13a and the outer end surface in the axial direction of the outer ring 2a are opposed to each other. In other words, the portion closer to the inner diameter of each through hole 13a is opened to the portion defining the radial labyrinth seal 32 on the inner side surface in the axial direction of the rotation side flange 9a.

Thus, the portion closer to the inner diameter of each through hole 13a and the outer radial half of the radial labyrinth seal 32 are overlapped in the axial direction. In the portion where the inner diameter portion of each through hole 13a and the outer end surface in the axial direction of the outer ring 2a face each other, the cross-sectional area {in the rotational direction of the rotation-side flange 9a (see arrow α in FIG. 3)] corresponds to each through hole 13a. Since the cross-sectional area of the orthogonal virtual plane} is increased, as is clear from Bernoulli's theorem, the velocity of the air flow generated with the rotation of the rotation-side flange 9a is reduced (slow), and the pressure in the labyrinth seal 25 is also increased. growing.

This increase in pressure becomes a discharging force for discharging foreign matter to the external space. Accordingly, the foreign matter attracted to the rotation side flange 9a side is discharged into each through hole 13a by the action of the airflow and pressure generated by the rotation of the rotation side flange 9a (it is attracted to the through hole 13a side). ). Thereafter, the foreign matter is moved radially outward by the action of centrifugal force, and from the portion located on the radially outer side of the outer peripheral edge of the axially outer end surface of the outer ring 2a in the opening of each through hole 13a. It is discharged to the external space.

Especially in the case of this embodiment, the outer diameter _{D 2a} of the outer ring 2a, the difference between the diameter _{D 13a} of the inscribed circle of the radially inner end of each through hole 13a of the ₍₌ D _{2a -D 13a),} about 1 ~ 8 mm Therefore, foreign matter can be easily discharged into each through hole 13a. That is, if the difference is smaller than 1 mm, the pressure in the labyrinth seal 25 cannot be sufficiently increased, and there is a possibility that the exhaust force cannot be obtained sufficiently. On the other hand, if the difference is larger than 8 mm, the bearing unit 1a may be increased in size and weight, or it may be difficult to secure the radial length of the radial labyrinth seal 32. Moreover, when each through-hole 13a has the function for inserting a tool when performing various operations, it becomes difficult to insert the tool. In contrast, in the case of the bearing unit 1a of the present embodiment, along with to face the inner diameter near portion of each through hole 13a and the axially outer end face of the outer ring 2a, the difference between the outer diameter D _2a and diameter D _13a It is regulated to an appropriate range. Thereby, the foreign matter can hardly reach the portion where the tip edge of the seal lip constituting the seal ring 18 is in contact. Therefore, foreign matter enters the sliding contact portion between the tip edge of the seal lip and the axial inner surface of the rotation side flange 9a, and damage such as abnormal wear occurs in the sliding contact portion over a long period of time. Can be prevented. As a result, the effect of preventing foreign matter from entering the rolling element installation space 19 can be maintained well over a long period of time, and the durability of the bearing unit 1a can be further improved.

Furthermore, in the case of this example, each through-hole 13a which is a foreign matter discharge hole is a cylindrical hole provided in a state where the inner diameter of the inner peripheral surface does not change in the axial direction and penetrates the rotation side flange 9a in the axial direction. . For this reason, with the rotation of the rotation-side flange 9a, the flow of the airflow flowing along the inner peripheral surface of each through hole 13a can be rectified to form a laminar flow.

In addition, when implementing this invention, it is good also considering the internal peripheral surface of each through-hole 13a which is a foreign material discharge hole as a conical surface shape inclined in the direction where an internal diameter becomes small, so that it goes to an axial direction outward. That is, the foreign matter discharge hole may be a conical hole. If the inner peripheral surface of the foreign material discharge hole is a conical surface inclined in a direction in which the inner diameter becomes smaller as it goes outward in the axial direction, the velocity of the airflow flowing from the inner side to the outer side in the foreign material discharge hole Can be made faster as it goes outward in the axial direction. For this reason, the foreign matter discharged into the foreign matter discharge hole along with the rotation of the rotation side flange can be easily discharged from the axially outer opening of the foreign matter discharge hole to the external space. Regardless of the structure of the cylindrical hole or the conical hole used as the foreign matter discharge hole, the inner peripheral surface of the foreign matter discharge hole is a smooth surface whose inner diameter does not repeatedly change in the axial direction. To do.

On the other hand, when the foreign matter discharge hole is, for example, a screw hole, that is, when the inner peripheral surface of the foreign matter discharge hole has a shape in which the inner diameter repeatedly changes in the axial direction, the flow of airflow flowing through each foreign matter discharge hole is It becomes turbulent. In this case, the effect of discharging foreign matter due to the action of airflow and pressure generated as the rotation-side flange rotates is not as good as when the foreign matter discharge hole is a cylindrical hole or a conical hole.

Moreover, when implementing this invention, a foreign material discharge | emission hole can also be made into a bottomed hole opened only to the axial direction inner surface of the rotation side flange. If the foreign matter discharge hole is a bottomed hole, the strength and rigidity of the rotation side flange can be easily ensured as compared with the case where the foreign matter discharge hole is a through hole.

[Second Example of Embodiment]
FIG. 4 shows a second example of the embodiment of the present invention. Of the outer end surface of the outer ring 2b in the axial direction, the portion positioned at the lower end portion with the bearing unit 1b supported by the suspension device is axially inward in the radial direction (in a state of opening to both inner and outer peripheral surfaces). A concave groove 33 is provided. Such a concave groove 33 is provided at the same time when the outer ring 2b is manufactured by subjecting a metal material such as carbon steel to forging which is plastic processing. However, the concave groove 33 can also be provided by cutting the axially outer end surface of the outer ring 2b after the outer ring 2b is forged.

According to the present example as described above, the phase in the circumferential direction of the portion closer to the inner diameter of the through hole 13a and the groove 33 is the same (the phase in the circumferential direction between the portion closer to the inner diameter of the through hole 13a and the groove 33 is the same. In this state, the speed of the air flow generated with the rotation of the rotation side flange 9a can be reduced, and the pressure in the labyrinth seal 25 can be increased.

Further, in the case of this example, the concave groove 33 is provided in a portion of the outer end surface in the axial direction of the outer ring 2b located at the lower end portion with the bearing unit 1b supported by the suspension device. That is, the direction in which foreign matter is discharged (pushed out) with the increase in pressure in the labyrinth seal 25 based on the presence of the concave groove 33 and the action direction of gravity are made to coincide with each other to further increase the foreign matter discharge effect. Can be improved.

In consideration of the foreign matter discharging effect as described above, it is most preferable that the concave groove 33 is provided in a portion positioned at the lower end portion with the bearing unit 1b supported by the suspension device. However, if the concave groove is provided in a portion located below (lower half) with the bearing unit 1b supported by the suspension device, the above-described foreign matter discharge effect is provided to some extent (the portion located at the lower end portion). But not as much as you can).

Also, when the concave groove 33 is provided in the upper (upper half) portion of the bearing unit 1b supported by the suspension device, the labyrinth seal (although it cannot obtain the effect of gravity). It is possible to obtain a foreign matter discharging effect due to an increase in the pressure in 25.

The concave grooves 33 can also be provided at a plurality of locations in the circumferential direction on the axially outer end surface of the outer ring 2b.
The configuration and operation of the other parts are the same as in the first example of the embodiment described above.

[Third example of embodiment]
5 to 6 show a third example of the embodiment of the present invention. An outer ring side recess 34 is provided in a portion of the outer peripheral surface of the outer ring 2c in the axial direction that coincides with the through hole 36 (see FIG. 1) provided in the stationary flange 6 in the circumferential direction. The outer ring side recess 34 opens to the axially outer end face of the outer ring 2c and is recessed radially inward.

The radial depth of each outer ring side recess 34 is constant in the outer half portion in the axial direction, and is made smaller toward the inner side in the axial direction in the inner half portion in the axial direction. That is, the diameter D ₃₄ of the inscribed circle of the bottom surface of the outer wheel side recess 34 around the central axis of the bearing unit 1c, are larger toward axially inward. And the axial direction inner end edge (back end edge) of each outer ring side recess 34 is positioned outside the axial direction outer end edge of the outer ring raceway 5c (see FIG. 1) in the axial direction outer row in the axial direction. . For this reason, even when each outer ring side recess 34 is provided, it is possible to prevent a decrease in rigidity of a portion of the outer ring 2c provided with the outer ring raceway 5c in the outer row in the axial direction. Accordingly, it is possible to prevent the roundness of the outer ring raceway 5c in the outer row in the axial direction from deteriorating in a state where the stationary flange 6 is coupled and fixed to the knuckle constituting the suspension device.

Through holes provided in the rotation side flange 9a as shown in FIG. 6 (A), the shape of the bottom surface at the opening of each outer ring side recess 34 (the shape of the bottom when the opening is viewed from the outside in the axial direction). around the 13a central axis of, and a large arc-shaped in diameter than the inner diameter _{d 13a} of each through hole 13a. However, the shape of the bottom surface in the opening of each outer ring side recess 34 can be a V shape as shown in FIG. 6B, a linear shape as shown in FIG. In any case, the diameter of the inscribed circle d ₃₄ of at the bottom to the opening of the outer concave portion 34 around the central axis of each through hole 13a, larger than the inner diameter d _13a of each through hole 13a To do.

The outer ring side recess 34 is provided at the same time when the outer ring 2c is formed by subjecting a metal material such as carbon steel to a forging process which is a plastic process. However, the outer ring side recess 34 can be provided by cutting the outer ring 2c after the outer ring 2c is made by forging.

In the case of this example, one of the outer ring side recesses 34 is provided at a portion located at the lower end with the outer ring 2c supported by the vehicle suspension. Thereby, the pressure in the labyrinth seal 25 is increased based on the presence of the one outer ring side recess 34, and the direction in which foreign matter is discharged (pushed out) and the direction of action of gravity coincide with each other.

In the case of this example, the diameter D _13a of the inscribed circle at the radially inner end of each through-hole 13a centered on the central axis of the bearing unit 1c is set as the outer ring centered on the central axis of the bearing unit 1c. is made larger than the diameter _{D 34} of at inscribed circle axially outer end edge of the bottom surface of the side recess _{_{34 (D 13a> D 34)}} .

Accordingly, when a tool is inserted into each through-hole 13a, it is possible to prevent the tip of the tool from interfering with the axially outer end surface of the outer ring 2c, and work performed by inserting the tool into each through-hole 13a. It is possible to prevent a decrease in sex. In other words, it is possible to prevent the workability of work such as attaching / detaching the bearing unit 1c to / from the suspension device, and attaching / detaching parts (supports and calipers) constituting the brake device from the suspension device.

When the bearing unit 1c is attached to the suspension device, the phase in the circumferential direction of the screw hole provided in the knuckle constituting the suspension device and the through hole 36 of the stationary side flange 6 are made to coincide with each other, and the rotation side flange The phases in the circumferential direction of the through holes 13a of 9a and the through holes 36 are made to coincide with each other. In this state, a tool is inserted from the outside in the axial direction of each through hole 13a, and a bolt inserted through each through-hole 36 from the outside in the axial direction is screwed into each screw hole by this tool and further tightened. Thereby, the stationary side flange 6 is coupled and fixed to the knuckle. Further, when the bearing unit 1c is removed from the suspension device, the tool is applied from the outside in the axial direction of each through hole 13a in a state where the phases in the circumferential direction of each through hole 13a and each through hole 36 coincide with each other. Is inserted, and the bolts screwed into the screw holes are loosened by inserting the through holes 36 with a tool.

In the case of this example, in the outer peripheral surface of the outer ring 2c in the axial direction, the diameter of the outer ring 2c is open to the outer peripheral surface of the outer ring 2c in a portion where the phase in the circumferential direction coincides with each through hole 36. The outer ring side recesses 34 that are recessed inward in the direction are respectively provided, and the diameter D ₃₄ of the inscribed circle at the outer edge in the axial direction of the bottom surface of each outer ring side recess 34 centered on the central axis of the bearing unit 1c, It is smaller than the diameter _{D 13a} of the inscribed circle of the radially inner end of each through hole 13a around the center axis of the bearing unit _{_{1c (D 34 <D 13a)}} .

For this reason, when the tool is inserted from the outside in the axial direction of each through hole 13a during the operation of tightening or loosening the bolt, the tip of the tool interferes with the axial outer end surface of the outer ring 2c. Can be prevented. Accordingly, the diameter D _13a of the inscribed circle of the radially inner end of each through hole 13a around the center axis of the bearing unit 1c is smaller than the outer diameter D _2c of the axially outer end face of the outer ring 2c ( Even in the case of D _13a <D _2c ), it is possible to prevent the assembling property of the bearing unit 1c from being attached to the knuckle (workability of work performed by inserting a tool into each through hole 13a). Further, in the case of this example, (and to reduce the depth from the outer peripheral surface) more greatly to that toward the diameter D ₃₄ axially inwardly of the inscribed circle of the bottom surface of the outer ring recess 34 for The tool can be guided inward in the axial direction by preventing the tool from being caught in the outer ring side recesses 34.

The outer ring side recess 34 as described above coincides with a fixing position (mounting hole or the like) of a support or caliper (not shown) that constitutes a braking device together with the brake rotating body 35 (see FIG. 3) in the circumferential direction. It can also be provided.
The configuration and operation of the other parts are the same as in the first and second examples of the above-described embodiment.

[Fourth Example of Embodiment]
7 and 8 show a fourth example of the embodiment of the present invention. A large-diameter portion 37 having an outer diameter and an inner diameter larger than those adjacent to the inner side in the axial direction is provided at the outer end in the axial direction of the outer ring 2d. And the diameter of the through-hole 13a provided in the rotation side flange 9a centering on the center axis | shaft of the bearing unit 1d about the outer diameter of the axial direction outer end surface of the large diameter part 37, ie, the axial direction outer end surface of the outer ring | wheel 2d. It is larger than the diameter of the inscribed circle at the inner end in the direction. The large-diameter portion 37 is formed on one end of the metal material provided in a cylindrical shape (on the outer end in the axial direction of the outer ring 2d) when the outer ring 2d is manufactured by subjecting a metal material such as carbon steel to plastic processing such as forging. The corresponding end portion is provided by plastic deformation so as to expand the left end portion in FIG.

That is, as shown in FIG. 8, a metallic and cylindrical intermediate material 38 is set in a die 39. The inner peripheral surface of the die 39 has a stepped cylindrical shape in which the inner diameter of one end (opening side end) is larger than the inner diameter of the portion adjacent to the other side. In this way, the outer diameter of the intermediate portion or the other end portion of the intermediate material 38 is restrained by the die 39. In this state, the diameter-enlarging punch 40 is pushed inward from the opening on one end side in the radial direction of the intermediate material 38, and one end portion of the intermediate material 38 is plastically deformed radially outward to increase the outer diameter and inner diameter. A diameter portion 37 is provided. The processing for providing such a large diameter portion 37 can be performed, for example, in the final step of the manufacturing process of the outer ring 2d. Preferably, a die 39 that can be divided in the circumferential direction is used.

According to the present example as described above, even when a structure that can satisfactorily maintain the foreign object intrusion effect into the rolling element installation space 19 (see FIG. 1) over a long period of time is adopted, an increase in weight can be suppressed. Can do. That is, in the structures of the first to third examples of the above-described embodiment, the outer diameter of the outer ring 2a (2b, 2c) is increased by increasing the outer diameter of the outer end surface of the outer ring 2a (2b, 2c) in order to improve the foreign matter intrusion effect. There is a possibility that the radial thickness of (2b, 2c) increases and the weight increases. On the other hand, in the case of the bearing unit 1d of the present example, the large diameter portion 37 is provided at the axially outer end portion of the outer ring 2d by plastically deforming one end portion of the intermediate material 38 radially outward. The outer diameter of the outer end surface in the axial direction of the portion 37 is made larger than the diameter of the inscribed circle at the inner end portion in the radial direction of each through hole 13a. Therefore, it is possible to maintain a good foreign substance intrusion preventing effect over a long period while suppressing an increase in weight.

Since the bearing unit 1d is a so-called unsprung load provided on the road surface side of the spring constituting the suspension device, the weight reduction makes it possible to improve the running performance centered on ride comfort and running stability. can get.

In the case of this example, an inclined surface portion 41 is formed on the outer peripheral surface of the outer ring 2d at a continuous portion between the axial middle portion of the outer ring 2d and the large-diameter portion 37 provided at the outer end portion in the axial direction of the outer ring 2d. It is formed. The inclined surface portion 41 can prevent water such as muddy water adhering to the outer peripheral surface of the outer ring 2d from entering the rolling element installation space 19 from the axially outer side opening of the outer ring 2d along the outer peripheral surface of the outer ring 2d (damming. Can do it). Also from this aspect, the effect of preventing foreign matter from entering the rolling element installation space 19 can be improved.
Other configurations and operations are the same as those in the first to third examples of the above-described embodiment.

[Fifth Example of Embodiment]
9 and 10 show a fifth example of the embodiment of the present invention. A concave portion 42 that is recessed inward in the radial direction is provided over the entire circumference at a portion near the outer end in the axial direction of the outer ring 2e. According to this example, the weight of the outer ring 2e, and hence the increase in unsprung load, can be suppressed by providing the recess 42, so that the running performance of the vehicle equipped with the bearing unit 1e can be improved. I can plan. Further, it is a recess that moisture such as muddy water adhering to the outer peripheral surface of the outer ring 2e enters the rolling element installation space 19 (see FIG. 1) from the axially outer opening of the outer ring 2e along the outer peripheral surface of the outer ring 2e. 42 can prevent this.

In order to manufacture the outer ring 2e as described above, as shown in FIG. 10, a stepped cylinder made of metal and having an outer diameter at one end (the left end in FIG. 10) smaller than the outer diameter of the portion adjacent to the other. An intermediate material 38a having an outer peripheral surface is set in the die 39a. A portion closer to one end (closer to the opening end) of the inner peripheral surface of the die 39a has a convex portion 43 protruding radially inward over the entire periphery. Thus, the outer diameter of the intermediate | middle part thru | or other end part of the intermediate | middle raw material 38a is restrained by the die | dye 39a. In this state, the diameter-enlarging punch 40a is pushed inward in the radial direction of the intermediate material 38a from the opening on one end side, and one end portion of the intermediate material 38a is plastically deformed radially outward to expand the outer diameter and inner diameter. Thereby, the recessed part 42 is provided in the part near the axial direction outer end of the outer ring 2e (the part near one end of the intermediate material 38a).
Other configurations and operations are the same as those in the first to fourth examples of the above-described embodiment.

This application is based on Japanese Patent Application No. 2015-166818 filed on August 26, 2015 and Japanese Patent Application No. 2016-108554 filed on May 31, 2016, the contents of which are incorporated herein by reference.

In the present invention, as shown in FIG. 1 of the first example of the embodiment described above, the pitch circle diameter of the rolling elements (balls or tapered rollers) in the axially outer row is larger than the pitch circle diameter of the rolling elements in the axially inner row. It can be preferably implemented with a large structure in which the outer diameter of the outer end of the outer ring in the axial direction is large. However, the present invention is applied to a structure in which the pitch circle diameters of the rolling elements in both rows are equal to each other, or a structure in which the pitch circle diameter of the rolling elements in the axially inner row is larger than the pitch circle diameter of the rolling elements in the axially outer row. You can also do it.
In addition, the present invention is not limited to the bearing unit for the driven wheel as shown in FIGS. 1 and 11, and a spline hole through which the drive shaft is spline-engaged in use in the center portion of the hub body is axially penetrated. It can also be implemented with a bearing unit for driving wheels provided in the state.

1, 1a to 1e Wheel bearing rolling

bearing unit

2, 2a to 2e

Outer ring

3,

3a Hub

4, 4a, 4b Ball 5a to 5d Outer ring raceway 6 Stationary side flange 7 Screw hole 8a to 8d

Inner ring raceway

9, 9a Rotation side flange DESCRIPTION OF

SYMBOLS

10, 10a, 10b Cage 11 Mounting hole 12

Stud

13, 13a Through-

hole

14, 14a Hub main body 15 Inner ring 16 Small diameter step part 17 Caulking part 18 Seal ring 19 Rolling body installation space 20 Inner peripheral surface side step part 21 Outer peripheral surface side Stepped portion 22 Stepped surface 23 Cover 24 Encoder 25 Labyrinth seal 26 Outer ring side stepped portion 27 Thick portion 28 Thinned portion 29 Stepped portion 30 Flange side stepped portion 31 Axial labyrinth seal 32 Radial direction labyrinth seal 33 Concave groove 34 Outer ring side Concave part 35 Rotating body for braking 36 Through hole 37

Large diameter part

38,

38a Intermediate material

39,

39a Dice

40, 40a Diameter expansion punch 41 Inclined surface part 42 Concave part 43 Convex part

Claims

An outer ring which has a double row outer ring raceway on the inner peripheral surface and which is supported by a suspension device in a use state and does not rotate;
A hub disposed coaxially with the outer ring on the inner diameter side of the outer ring, the outer ring having a double-row inner ring raceway in a portion facing the double-row outer ring raceway, and an outer end in the axial direction of the outer ring The hub having a rotating side flange for coupling and fixing a braking rotator and a wheel to a portion protruding axially outward from the portion;
Between the double row outer ring raceway and the double row inner ring raceway, a plurality of rolling elements provided so as to be freely rollable for each row,
With
The rotation side flange is provided with a foreign matter discharge hole that opens on at least an axial inner side surface of both side surfaces in the axial direction of the rotation side flange.
In the wheel bearing rolling bearing unit,
A wheel bearing rolling bearing unit in which an outer diameter of an outer end surface in the axial direction of the outer ring is larger than a diameter of an inscribed circle at a radially inner end portion of the foreign matter discharge hole centered on a central axis of the hub.