JP2017044332A - Wheel support rolling bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a structure which can easily discharge foreign matters intruded from a clearance between an axial outer end face of an outer ring and an axial inside face of a rotation-side flange.SOLUTION: An outside diameter of an axial outer end face of an outer ring 2a is set larger than a diameter of an inscription circle of an inner end part of a through-hole 13a which is formed at a rotation-side flange 9a in a radial direction with a center axis of a wheel support rolling bearing unit 1a as a center. A cross section is set large at a portion in which an inside-diameter shifted portion of the through-hole 13a and the axial outer end face of the outer ring 2a oppose each other, and a speed of an airflow which is generated accompanied by the rotation of the rotation-side flange 9a is decelerated, thus increasing pressure in a labyrinth seal 25.SELECTED DRAWING: Figure 1

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.

FIG. 11 shows an example of a conventional structure described in Patent Document 1 as a wheel bearing rolling bearing unit for rotatably supporting a wheel with respect to a suspension device of an automobile. The wheel-supporting rolling bearing unit 1 supports a hub 3 on the inner diameter side of an outer ring 2 through a plurality of balls 4 and 4 so as to be rotatable. Outer ring 2 is made of medium carbon steel, and has double-row outer ring raceways 5a and 5b on the inner peripheral surface and stationary flange 6 on the outer peripheral surface. Such an outer ring 2 does not rotate because it is coupled and fixed to a knuckle constituting the suspension device by bolts screwed into screw holes 7 provided at a plurality of circumferential positions of the stationary flange 6. The hub 3 has double-row inner ring raceways 8a and 8b and a rotation side flange 9 on the outer peripheral surface, and rotates with a wheel coupled and fixed to the rotation side flange 9 in use. The balls 4 and 4 are made of bearing steel or ceramic and are held by cages 10 and 10 between the double row outer ring raceways 5a and 5b and the double row inner ring raceways 8a and 8b. A plurality are provided for each row so as to be freely rollable. Further, mounting holes 11 are provided at a plurality of locations in the circumferential direction of the rotation side flange 9 so as to penetrate the rotation side flange 9 in the axial direction. Then, a base end portion of a plurality of studs 12 having serration portions in a part thereof is press-fitted into each of the mounting holes 11, and a rotating body for braking such as a disc rotor or a drum brake is inserted into the rotation side flange 9, The wheel constituting the wheel can be supported and fixed. Further, a through hole 13 is provided in a portion between the mounting holes 11 adjacent in the circumferential direction in the rotation side flange 9. These through-holes 13 are screwed into the screw holes 7 of the stationary flange 6 (or inserted into the through-holes) in order to reduce the weight of the hub 3 and thus the wheel-supporting rolling bearing unit 1 as a whole. ) It is provided to insert a tool for the purpose of tightening a bolt or attaching a component constituting a braking device to a suspension device. In order to reduce the moment of inertia of the hub 3 and improve the running performance and the fuel efficiency performance centering on the acceleration performance, such a through hole 13 is formed as much as possible on the outer diameter of the rotation side flange 9. It is preferable to provide in the side part. 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 wheel supporting rolling bearing unit 1 is set to the axis of the outer ring 2. It is made larger than the outer diameter D ₂ of the outward end.

  The hub 3 is formed by coupling and fixing a hub body 14 and an inner ring 15. Of these, the hub body 14 is made of medium carbon steel, and is a portion near the outer end in the axial direction (“outer” in the axial direction means the outer side in the width direction of the vehicle when assembled to the automobile. FIGS. On the other hand, the right side of FIGS. 1 to 5 and 7 to 11 which is the center side in the width direction of the vehicle is referred to as “inside” in the axial direction.) Of the double-row inner ring raceways 8a and 8b, the axially outer row inner ring raceway 8a is directly provided on the outer circumferential surface of the axially intermediate portion.

  On the other hand, the inner ring 15 is made of bearing steel, and the inner ring raceway 8b in the axially inner row of the double row inner ring raceways 8a and 8b is provided on the outer peripheral surface. Such an inner ring 15 is fitted and fixed to a small-diameter step portion 16 provided near the inner end of the hub body 14 in the axial direction, and the inner end surface in the axial direction is set to the inner end of the hub body 14 in the axial direction. The hub body 14 is coupled and fixed by being pressed down by the caulking portion 17 provided.

  Further, a gap between the inner peripheral surface of the outer end 2 in the axial direction of the outer ring 2 and the outer peripheral surface of the intermediate portion in the axial direction of the hub 3 is set to the inner side surface in the axial direction of the rotation side flange 9 or Outside the axial direction of the rolling element installation space 19 in which the balls 4, 4 are installed by closing the outer peripheral surface with a seal ring 18 having three seal lips that are in sliding contact with each other over the entire circumference. The end opening is closed. In the case of the illustrated example, the wheel support rolling 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 axially outer end side opening 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). And, when traveling on a rough road such as a gravel road, foreign matters such as relatively large sand particles enter from this gap, and these foreign matters are formed between the seal lip constituting the seal ring 18 and the axial inner side surface of the rotary side flange 9. If it enters the sliding contact portion, damage such as abnormal wear may occur in the sliding contact portion.

JP 2007-1000071 A

  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 invention includes an outer ring, a hub, and a plurality of rolling elements.
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 is disposed coaxially with the outer ring on the inner diameter side of the outer ring, and a double-row inner ring raceway is disposed on a portion of the outer peripheral surface facing the double-row outer ring raceway from an outer end in the axial direction of the outer ring. Each has a rotation-side flange for connecting and fixing the braking rotator and the wheel to the portion protruding outward in the axial direction.
Each of the rolling elements is provided so as to be able to roll a plurality for each row between the double row outer ring raceway and the double row inner ring raceway.
And, in one or more circumferential directions of the rotation side flange, foreign matter discharge holes (at both sides in the axial direction of the rotation side flange) opened on at least the axial inner side surface of the both side surfaces in the axial direction of the rotation side flange. An open through-hole or a bottomed hole opened only in the axially inner surface).
In particular, in the wheel support rolling bearing unit of the present invention, the outer diameter of the outer end surface of the outer ring in the axial direction is centered on the center axis of the hub (the center axis of the wheel support rolling bearing unit). The diameter is larger than the diameter of the inscribed circle at the radially inner end of the foreign matter discharge hole.
Such a foreign matter discharge hole is 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 into

  When the rolling bearing unit for supporting a wheel of the present invention as described above is implemented, 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, among the axially inner side surfaces of the rotation side flange, a thick portion provided at a proximal end portion (base portion) and a thin portion having a smaller thickness (axial thickness) than the thick portion 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 a portion adjacent to the axially outer side is provided. An axial labyrinth seal is provided between the outer ring side stepped portion and the flange side stepped portion by causing the outer ring side stepped portion and the flange side stepped 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 on the flange side step portion) 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 the rolling bearing unit for supporting a wheel of the present invention as described above is implemented, 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 (this foreign matter discharge hole is a cylindrical hole). Is preferable). 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 decreases as it goes outward in the axial direction (the foreign matter discharge hole is 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 rolling bearing unit for supporting a wheel of the present invention as described above is implemented, it is preferable that the outer ring is opened at one or a plurality of locations in the circumferential direction on the outer end surface and the outer circumferential surface in the axial direction of the outer ring. Thus, an outer ring side recess is provided.
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 rolling bearing unit for supporting a wheel of the present invention as described above, it is possible to easily discharge 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 rotating flange.
That is, when a 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 is accompanied by the rotation of the rotation side flange. As is clear from Bernoulli's theorem, the airflow generated between the axially outer end surface of the outer ring and the axially inner surface of the rotating flange attracts the rotating flange toward the rotating flange where the speed is high and the pressure is low. In the case of the present invention, 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 made smaller than the outer diameter of the outer end surface in the axial direction of the outer ring. A portion closer to the inner diameter of the outer ring is opposed to the outer end surface in the axial direction of the outer ring. In a portion where the portion closer to the inner diameter 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 becomes smaller (slower), and the outer end surface in the axial direction of the outer ring The pressure in the gap between the two also increases. Accordingly, the foreign matter attracted to the rotating flange side is discharged into the foreign matter discharge hole by the action of the air flow and pressure (drawn to the foreign matter discharge hole side), and then is subjected to the external space by the action of centrifugal force. To be discharged. As a result, the 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 support rolling bearing unit can be prevented. Can be improved.

Sectional drawing which shows the 1st example of embodiment of this invention. The X section enlarged view of FIG. The schematic diagram equivalent to the YY cross section of FIG. 1 shown in the state which supported and fixed the braking rotary body to the rotation side flange. 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. Similarly ZZ sectional drawing of FIG. 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 to provide a large diameter part similarly. 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 similarly. 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. The wheel support rolling bearing unit 1a 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. Of these, the outer ring 2a is provided with double-row outer ring raceways 5c, 5d on the inner peripheral surface and a stationary flange 6 at the axially intermediate portion of the outer peripheral surface. Of these 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 ring surface in the axial direction of the outer ring 2a is inclined in a direction closer to the outer side in the axial direction than the outer ring raceway 5d in the inner row in the axial direction so that the inner diameter decreases toward the inner side in the axial direction. An inner peripheral surface side step portion 20 is provided. Further, through holes 36 through which bolts (not shown) for connecting and fixing the outer ring 2 a to knuckle constituting the suspension device are respectively provided at a plurality of locations in the circumferential direction of the stationary flange 6.

The hub 3a is a combination of the hub body 14a and the inner ring 15, and supports a braking rotator 35 (see FIG. 3) such as a rotor or a drum and a wheel on a portion near the outer end in the axial direction of the outer peripheral surface. The rotation side flange 9a for this purpose is also provided with double-row inner ring raceways 8c and 8d at the intermediate portion and the inner end portion, respectively. Of these double-row inner ring raceways 8c, 8d, the outer diameter of the inner ring raceway 8c in the axially outer row is larger than that of the inner ring raceway 8d in the axially inner row. Further, mounting holes 11 for press-fitting the base end portion of the stud 12 for supporting and fixing the braking rotator 35 and the wheels to the rotation side flange 9a are provided at a plurality of locations in the circumferential direction of the rotation side flange 9a. Provided. And in the rotation side flange 9a, through holes 13a, each of which is a foreign matter discharge hole described in the claims, in at least one of the portions between the mounting holes 11 adjacent in the circumferential direction, The rotating side flange 9a is provided in a state of penetrating in the axial direction (opening on both axial sides of the rotating 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, the diameter D _13a of the inscribed circle at the radially inner end of each through hole 13a centering on the central axis of the wheel supporting rolling bearing unit 1a is set to the outer diameter D of the outer circumferential surface of the outer ring 2a. _It is smaller than _2a ( _D13a < _D2a ). The inner diameter of the respective through holes 13a, and the difference between the amount {these outer diameter _{D 2a} and diameter _{D 13a} to be larger than the outer diameter _{D 2a} the diameter _{D 13a (= D 2a -D 13a} ) is Depending on the size (outer diameter), weight, etc. of the brake rotating body 35 and the wheel supported and fixed to the rotation side flange 9a, in the case of a general wheel support rolling bearing unit for automobiles, The inner diameter of each through hole 13a is about 20 to 30 mm, and the difference is about 1 to 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 circumferential 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. The outer peripheral surface side stepped portion 21 is provided to connect the axially inner portion having a small outer diameter and the axially outer portion having a large outer diameter. Further, a small-diameter step portion 16 is provided at a portion closer to the inner end in the axial direction of the hub main body 14a, which is closer to the inner side in the axial direction than the step portion 21 on the outer peripheral surface side. Then, the inner ring 15 having the inner ring raceway 8d in the axially inner row provided on the outer peripheral surface is externally fitted to the small-diameter stepped portion 16, and the caulking portion 17 is provided at the inner end in the axial direction of the hub body 14a. The inner ring 15 is pressed against the stepped surface 22 existing at the axially outer end of the small diameter stepped portion 16. In this state, the inner ring 15 is coupled and fixed to the hub body 14a.

  Each of the balls 4a and 4b is held in the cages 10a and 10b between the double row outer ring raceways 5c and 5d and the double row inner ring raceways 8c and 8d. Each is provided so that it can roll freely. In this state, the balls 4a and 4b arranged in a double row are provided with a contact angle of a rear combination type together with a preload. Further, the pitch circle diameters of the balls 4a and 4b in each row differ from each other in accordance with the difference between the inner diameters of the double row outer ring raceways 5c and 5d and the outer diameters of 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 diameter of the balls 4a, 4a in the axially outer row is made smaller than the diameter of the balls 4b, 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. In the case of a rolling bearing unit for supporting a wheel that is heavy 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, the axial outer end opening of the rolling element installation space 19 that exists between the inner peripheral surface of the outer ring 2a and the outer peripheral surface of the hub 3a and in which the balls 4a and 4b are installed is provided. These are sealed 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 flange 9a on the rotation side over the entire periphery. I am letting. Further, the inner end opening in the axial direction of the outer ring 2a is closed by a cover 23 which is attached to this opening portion and is made of a non-magnetic material and has a bottomed cylindrical shape. Encoder 24 is fitted and fixed. 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.

  Further, 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 rotating side flange 9a. That is, the outer ring side step part 26 having a larger inner diameter than the part adjacent to the inner side in the axial direction (the part 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, of the inner side surface in the axial direction of the rotation side flange 9a, a thick portion 27 provided at a proximal portion (base portion) and a thickness (axial thickness) larger than the thick portion 27. A notch portion having a crank-shaped cross section is provided at the axially inner end portion of the step portion 29 having a circular cross section or a substantially circular arc shape, which is continuous with the small thin portion 28, and from a portion adjacent to the outside in the axial direction. Also, a flange-side step portion 30 having a small outer diameter is provided. An axial labyrinth seal 31 is provided between the outer ring side step portion 26 and the flange side step portion 30 by causing the outer ring side step portion 26 and the flange side step portion 30 to face each other in the radial direction. ing. At the same time, the outer ring 2a is made to oppose the outer ring 2a by causing the outer circumferential surface of the outer ring 2a and the step surface bent at a right angle from the axial outer end of the flange-side step section 30 to approach each other in the axial direction. A radial labyrinth seal 32 is provided between the axial outer end surface of the flange and the step surface existing at the axial outer end of the flange-side step portion 30. That is, by providing the radial labyrinth seal 32 at a position that does not overlap with the seal ring 18 in the radial direction (a position that deviates from the seal ring 18 with respect to the axial direction) Foreign matter is prevented from entering the radial labyrinth seal 32 in the radial direction and passing through the radial labyrinth seal 32 to reach 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 (the labyrinth in the axial direction) of the labyrinth seal 25 whose cross-sectional shape is L-shaped. The sum of the axial length of the seal 31 and the radial length of the radial labyrinth seal 32) depends on the size and weight of the braking rotator 35 and the wheel supported and fixed to the rotation side flange 9a. Different. For example, in the case of a general wheel support rolling bearing unit for automobiles, 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, more preferably 0.57 to 0.8 mm, and the axial length L ₃₁ of the axial labyrinth seal 31 is preferably 0.6 mm to 1.4 mm, more preferably 0.7 to 1.mm. 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 of the radial labyrinth seal 32 is The length L 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. That is, if the radial width W ₃₁ of the axial labyrinth seal 31 is made smaller than 0.5 mm or the axial width W ₃₂ of the radial labyrinth seal 32 is made smaller than 0.8 mm, the wheel becomes a curb. There is a possibility that the outer end 2a of the outer ring 2a may come into contact (collision) with the rotation side flange 9a when riding on the outer ring 2a. On the other hand, when the radial width W ₃₁ of the axial labyrinth seal 31 is larger than 1.0 mm, or when the axial width W ₃₂ of the radial labyrinth seal 32 is larger than 1.5 mm, the labyrinth seal 25 is increased. There is a possibility that the effect of preventing foreign matter intrusion due to is not sufficiently obtained. 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 There is a possibility that the effect of preventing entry of foreign matter by 25 cannot be obtained sufficiently. On the other hand, if greater than 1.4mm and the axial length _{L 31} of the labyrinth seal 31 of the axial and radial name length _{W 32} in the radial direction of the labyrinth seal 32 is greater than 2.6 mm, the There is a possibility that the wheel-supporting rolling bearing unit 1a becomes large and heavy. 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. Increases the effect. 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 As much as possible, foreign matter that has entered the inside 25 is retained in the radial labyrinth seal 32. Thereby, as will be described later, the presence of the respective through holes 13a and the action of the air flow accompanying the rotation of the rotation-side flange 9a makes it easy to discharge foreign matter that has entered the labyrinth seal 25 to the external space. 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 wheel support rolling 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 the case of this example, the radial labyrinth seal 32 and the radial inner side of the radial labyrinth seal 32 are arranged between the axial outer end surface of the outer ring 2a and the axial inner side surface of the rotation side flange 9a. A labyrinth seal 25 including an axial labyrinth seal 31 that is bent inward in the axial direction from the end portion is provided. For this reason, it is possible to make it difficult for the foreign matter splashed when the vehicle equipped with the wheel bearing rolling bearing unit 1a travels to reach the portion where the tip edge of the seal lip constituting the seal ring 18 is in contact (this seal). Ring 18 can be protected).

Further, even if the foreign matter enters the labyrinth seal 25 (axial labyrinth seal 31), the foreign matter is moved into the labyrinth seal 25 (radial labyrinth as the rotary flange 9a rotates. As is clear from Bernoulli's theorem, the air flow generated in the seal 32) is drawn toward the rotating flange 9a, which has a high speed and a low pressure. Here, in this example, the diameter D _13a of the inscribed circle of the radially inner end of each through hole 13a around the central axis of the wheel supporting rolling bearing unit 1a, the axial direction of the outer ring 2a It is smaller than the outer diameter D _2a of the outer end surface (D _13a <D _2a ), and the portion closer to the inner diameter of each through hole 13a is opposed to the axial outer end surface of the outer ring 2a. In other words, a portion closer to the inner diameter of each of the through holes 13a is opened to a portion of the inner side surface in the axial direction of the rotation side flange 9a that defines the radial labyrinth seal 32, and the respective through holes 13a are opened. A portion closer to the inner diameter of the labyrinth and a radially outer half portion of the radial labyrinth seal 32 are overlapped in the axial direction. At 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 {the rotation direction of the rotation side flange 9a (the arrow in FIG. The cross-sectional area of the virtual plane orthogonal to α) increases, and as is clear from Bernoulli's theorem, the velocity of the airflow generated with the rotation of the rotation-side flange 9a decreases (slows), and the labyrinth The pressure in the seal 25 also increases. This increase in pressure becomes a discharge force for discharging foreign matter to the external space. Accordingly, the foreign matter attracted to the rotation side flange 9a is discharged into each through hole 13a by the action of airflow and pressure generated by the rotation of the rotation side flange 9a (to the through hole 13a side). And is moved radially outward by the action of centrifugal force, and is located radially outside the outer peripheral edge of the axially outer end surface of the outer ring 2a among the openings of the respective through holes 13a. It is discharged from the part to the outside 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),} 1~ Since the thickness is about 8 mm, the foreign matter can be easily discharged into the through holes 13a. That is, if the difference is smaller than 1 mm, the pressure in the labyrinth seal 25 cannot be sufficiently increased, and the discharge force may not be sufficiently obtained. On the other hand, if the difference is larger than 8 mm, the wheel-supporting rolling 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. Further, when each through hole 13a has a function for inserting a tool when performing various operations, it is difficult to insert the tool. On the other hand, in the case of the wheel bearing rolling bearing unit 1a of the present example, 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, and the outer diameter _D2a and the above-mentioned Since the difference from the diameter D _13a is regulated within an appropriate range, 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, when the 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, it is long that damage such as abnormal wear occurs in the sliding contact portion. Can be prevented over time. 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 wheel bearing rolling bearing unit 1a can be further improved.

  Further, 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. It is said. 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.

  When carrying out the present invention, 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 outside in the axial direction (the foreign matter discharge hole is a conical hole). If the inner peripheral surface of the foreign matter discharge hole is formed into a conical surface inclined in a direction in which the inner diameter becomes smaller as it goes outward in the axial direction, the airflow flowing from the inner side to the outer side in the foreign matter discharge hole The speed of the can be increased as it goes outward in the axial direction. For this reason, it is possible to easily discharge the foreign matter discharged into the foreign matter discharge hole to the external space from the axially outer opening of the foreign matter discharge hole as the rotation side flange rotates. 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 inner peripheral surface of the foreign matter discharge hole, such as a screw hole, has a shape in which the inner diameter repeatedly changes in the axial direction, the flow of the airflow flowing through each foreign matter discharge hole becomes turbulent, and the rotation side flange The effect of discharging foreign matter due to the action of airflow and pressure generated with the rotation of the nozzle 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 (compared to 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. In the case of the wheel-supporting rolling bearing unit 1b of this example, in the axially outer end surface of the outer ring 2b, the wheel-supporting rolling bearing unit 1b is supported on the suspension device in a state positioned at the lower end in the radial direction. As a result, a groove 33 is provided that is recessed inward in the axial direction (in a state where the inner and outer peripheral surfaces are open). Such a concave groove 33 is provided at the same time when the outer ring 2b is made by subjecting a metal material such as carbon steel to forging which is plastic working. 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, in the portion where the portion closer to the inner diameter of the through hole 13a provided in the rotation side flange 9a and the groove 33 are opposed (in a state where the phases in the circumferential direction coincide). The speed of the airflow 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 that is positioned at the lower end portion while the wheel support rolling bearing unit 1b is 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 direction of action of gravity coincide with each other, and the foreign matter discharge effect is achieved. It can be improved further.

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 located at the lower end portion in a state where the wheel-supporting rolling bearing unit 1b is supported by the suspension device. However, if the concave groove is provided in a portion located below (lower half) with the wheel bearing rolling bearing unit 1b supported by the suspension device, the above-described foreign matter discharge effect is provided to some extent (positioned at the lower end). But not as much as if it was provided in the part to be). In addition, even when the concave groove is provided in a portion positioned above (upper half) in a state where the wheel bearing rolling bearing unit 1b is supported by the suspension device (although the effect of gravity cannot be obtained, ) A foreign matter discharging effect can be obtained by increasing the pressure in the labyrinth seal 25. It is also possible to provide grooves at a plurality of locations in the circumferential direction on the outer end surface in the axial direction 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. In the case of the wheel support rolling bearing unit 1c of the present example, the phase in the circumferential direction of the outer peripheral surface of the outer ring 2c in the axial direction coincides with the through hole 36 (see FIG. 1) provided in the stationary flange 6. The outer ring side recesses 34 that are recessed inward in the radial direction in a state of opening in the axially outer end surface of the outer ring 2c are respectively provided in the portions to be performed. In the case of this example, the radial depth of each of the outer ring side recesses 34 is constant in the outer half of the axial direction, and is decreased toward the inner side in the axial direction of the inner half of the axial direction (the wheel support rolling). It is larger toward 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 axially inwardly). The axial inner end edge (back end edge) of each outer ring side recess 34 is positioned outside the axial outer end edge of the outer ring raceway 5c (see FIG. 1) in the axial outer row in the axial direction. I try to do it. For this reason, it is possible to prevent a decrease in rigidity of the outer ring 2c provided with the outer ring raceway 5c in the axially outer row due to the provision of the outer ring side recesses 34, and the stationary flange 6 can be used as a suspension device. 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 of being coupled and fixed to the knuckle to be configured.

In the case of this example, 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) is the rotation side as shown in FIG. about the center axis of the through holes 13a provided in the flange 9a, and an arc-shaped larger diameter than the inner diameter d _13a of each through hole 13a. However, the shape of the bottom surface at the opening of each of the outer ring side recesses 34 should be V-shaped as shown in FIG. 6B or linear as shown in FIG. You can also. In any case, the diameter of the inscribed circle d _{34 on} the bottom surface of the opening of each outer ring side recess 34 centered on the central axis of each through hole 13a is determined from the inner diameter d _{13a of} each through hole 13a. Also make it bigger. Such an 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, after the outer ring 2c is made by forging, the outer ring side recess 34 can be provided by cutting the outer ring 2c.

  In the case of this example, one of the outer ring side recesses 34 is provided in a portion located at the lower end portion with the outer ring 2c supported by a vehicle suspension device. 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 are made to coincide.

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

According to this example as described above, when a tool is inserted into each through hole 13a, it is possible to prevent the tip of the tool from interfering with the axial outer end surface of the outer ring 2c. Inserting a tool into the hole 13a, attaching / detaching the wheel bearing rolling bearing unit 1c to / from the suspension device, or attaching / detaching components (support or caliper) constituting the braking device to / from the suspension device It is possible to prevent the workability of such work from being deteriorated. That is, when the wheel-supporting rolling bearing unit 1c is attached to the suspension device, the phase in the circumferential direction between the screw hole provided in the knuckle constituting the suspension device and the through hole 36 of the stationary side flange 6 is determined. Are made to coincide with each other, and the phase in the circumferential direction of the through hole 13a of the rotation side flange 9a is made to coincide with the phase in the circumferential direction of each through hole 36. 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 flange 6 is coupled and fixed to the knuckle. Also, when removing the wheel-supporting rolling bearing unit 1c from the suspension device, the phase of each through hole 13a in the circumferential direction is matched with the phase of each through hole 36 in the circumferential direction. A tool is inserted from the outside in the axial direction of each through hole 13a, and the bolts inserted through the through holes 36 and screwed into the screw holes are loosened by the tool. In any case, in the case of this example, the axial direction of the outer ring 2c is located at a portion of the outer peripheral surface of the outer end portion in the axial direction of the outer ring 2c where the phase in the circumferential direction coincides with each through hole 36. Outer ring side recesses 34 that are recessed radially inward while being open to the outer end surface are provided, respectively, and the axial outer ends of the bottom surfaces of these outer ring side recesses 34 centering on the center axis of the wheel support rolling bearing unit 1c. the diameter D ₃₄ of at inscribed circle to the edge, less than the diameter D _13a of the inscribed circle of the radially inner end of each through hole 13a around the central axis of the wheel supporting rolling bearing unit 1c (D ₃₄ <D _13a ). For this reason, when tightening or loosening the bolt, when the tool is inserted from the outside in the axial direction of each through hole 13a, the tip of the tool interferes with the axially outer end surface of the outer ring 2c. ) Can be prevented. Therefore, the outer diameter D _2c of the axially outer end surface of the diameter D _13a of the inscribed circle of the radially inner end of each through hole 13a is the outer ring 2c around the central axis of the wheel supporting rolling bearing unit 1c Even if it is smaller (D _13a <D _2c ), the wheel support rolling bearing unit 1c can be assembled to the knuckle of the suspension device (the work performed by inserting a tool into each through hole 13a) Property) can be prevented from being damaged. Further, in the case of this example, (and to reduce the depth from the outer peripheral surface) of the more largely to that toward the diameter D ₃₄ axially inwardly of the inscribed circle of the bottom surface of the outer wheel side recess 34 Therefore, the tool can be guided inward in the axial direction by preventing the tool from being caught by the outer ring side recesses 34.
The outer ring side recess 34 as described above is provided in a portion that 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. You can also do things.
The configuration and operation of the other parts are the same as those in the first and second examples of the embodiment described above.

[Fourth Example of Embodiment]
7 and 8 show a fourth example of the embodiment of the present invention. In the case of the wheel support rolling bearing unit 1d of the present example, 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 axially outer end portion of the outer ring 2d. Then, the outer diameter of the large-diameter portion 37, that is, the outer diameter of the outer end surface of the outer ring 2d is provided on the rotation-side flange 9a centered on the central axis of the wheel support rolling bearing unit 1d. The diameter of the inscribed circle at the radially inner end of the through hole 13a is larger. The large-diameter portion 37 has one end portion of the metal material provided in a cylindrical shape (the shaft of the outer ring 2d) when the outer ring 2d is produced by subjecting a metal material such as carbon steel to plastic processing such as forging. It is an end corresponding to the outer end in the direction, and is provided by plastically deforming so as to expand the left end in FIG. That is, as shown in FIG. 8, the cylindrical intermediate material 38 made of metal has a stepped cylindrical inner circumference 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. It is set in a die 39 having a surface shape, and the outer diameter of the intermediate portion or the other end portion of the intermediate material 38 is constrained. In this state, the diameter-enlarging punch 40 is pushed into the intermediate material 38 radially inward from the opening on one end side, and one end portion of the intermediate material 38 is plastically deformed radially outward to expand the outer diameter and inner diameter. The large diameter portion 37 is provided. Such a process of providing the 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 that can be divided in the circumferential direction is used as the die 39.

  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 case of the structures of the first to third examples of the above-described embodiment, the outer ring 2a (2b, 2c) has a larger outer diameter on the outer end surface in the axial direction in order to improve the foreign matter intrusion effect. There is a possibility that the radial thickness of 2a (2b, 2c) increases and the weight increases. On the other hand, in the case of the wheel support rolling bearing unit 1d of this example, the large diameter portion 37 is formed at the axially outer end portion of the outer ring 2d by plastically deforming one end portion of the intermediate material 38 radially outward. And the outer diameter of the axially outer end surface of the large-diameter portion 37 is larger than the diameter of the inscribed circle of the radially inner end portion of each through hole 13a, thereby suppressing an increase in weight, The foreign matter intrusion preventing effect can be maintained well over a long period of time. The wheel-supporting rolling bearing unit 1d is a so-called unsprung load that is provided on the road surface side of the spring constituting the suspension device, so that the driving performance centered on ride comfort and running stability by weight reduction. The effect of improving can be obtained.

In the case of this example, the inclined surface portion 41 is an outer peripheral surface of a continuous portion between the axially intermediate portion of the outer ring 2d and the large-diameter portion 37 provided at the axially outer end portion of the outer ring 2d. It is possible to 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 through the outer peripheral surface of the outer ring 2d from the axially outer side opening 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.
The structure and operation of the other parts are the same as 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. In the case of the wheel support rolling bearing unit 1e of this example, a concave portion 42 that is recessed radially inward is provided on the outer ring 2e near the outer end in the axial direction. According to this example, the weight of the outer ring 2e and the increase in unsprung load can be suppressed by providing the recess 42, and the wheel bearing rolling bearing unit 1e is mounted. The running performance of the vehicle can be improved. Further, moisture such as muddy water adhering to the outer peripheral surface of the outer ring 2e may enter the rolling element installation space 19 (see FIG. 1) from the axially outer side opening of the outer ring 2e along the outer peripheral surface of the outer ring 2e. This can be prevented by the recess 42.

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 a cylindrical outer peripheral surface is set in a die 39a having a convex portion 43 projecting radially inward over the entire circumference near one end (closer to the opening end) of the inner peripheral surface, The outer diameter of the intermediate | middle part thru | or other end part of the intermediate | middle raw material 38a is restrained. In this state, the diameter-enlarging punch 40a is pushed into the radial inner side 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 increase the outer diameter and inner diameter. Accordingly, the concave portion 42 is provided in a portion near the outer end in the axial direction of the outer ring 2e (a portion 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 embodiment described above.

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. The structure can be preferably implemented with a structure in which the outer diameter of the outer end of the outer ring in the axial direction is large. However, in the present invention, the pitch circle diameters of the rolling elements in both rows are equal to each other, or 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. It can also be applied.
In addition, the present invention is not limited to a wheel support rolling bearing unit for a driven wheel as shown in FIGS. 1 and 11, but a spline hole for spline engagement of a drive shaft at the time of use is provided at the center of the hub body. It can also be implemented by a wheel bearing rolling bearing unit for driving wheels provided in a state penetrating in the direction.

DESCRIPTION OF SYMBOLS 1, 1a-1e Rolling bearing unit for wheel support 2, 2a-2e Outer ring 3, 3a Hub 4, 4a, 4b Ball 5a-5d Outer ring track 6 Stationary side flange 7 Screw hole 8a-8d Inner ring track 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 portion 35 Rotating body for braking 36 Through hole 37 Large diameter portion 38, 38a Intermediate material 39, 3 9a Die 40, 40a Diameter expansion punch 41 Inclined surface part 42 Concave part 43 Convex part

Claims (1)

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;
The outer ring is arranged coaxially with the outer ring on the inner diameter side of the outer ring, and a double-row inner ring raceway is arranged on an outer peripheral surface of the outer ring that is opposed to the double-row outer ring raceway. Hubs each having a rotation side flange for connecting and fixing a braking rotator and a wheel to a portion protruding in the direction,
A rolling element provided between the double row outer ring raceway and the double row inner ring raceway so as to be able to roll plurally for each row,
The rotation side flange is provided with a foreign matter discharge hole that opens at least on the inner side surface in the axial direction of both side surfaces in the axial direction of the rotation side flange.
In the wheel bearing rolling bearing unit,
A wheel-supporting rolling bearing characterized in that 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 centering on a central axis of the hub. unit.

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