JP6627577B2 - Rolling bearing unit for wheel support - Google Patents

Description

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

  A rolling bearing unit is used to rotatably support a vehicle wheel with respect to a suspension device. Further, in order to control the antilock brake system (ABS) or the traction control system (TCS), it is necessary to detect the rotation speed of the wheels. For this reason, in recent years, it has been recently required that the wheel is rotatably supported with respect to a suspension device by a wheel supporting rolling bearing unit in which a rotation speed detecting device is incorporated in the rolling bearing unit, and the rotation speed of the wheel is detected. It has been widely practiced.

  As an example of a conventional structure of a rolling bearing unit for supporting a wheel used for such a purpose, Patent Document 1 and the like describe a structure as shown in FIG. In the wheel bearing rolling bearing unit 1 having the conventional structure, a hub 3 as a rotating wheel is rotatably supported on the inner diameter side of an outer ring 2 as a stationary wheel.

  The outer race 2 has a double-row outer raceway 4a, 4b on the inner peripheral surface and a stationary flange 5 on the outer peripheral surface for coupling and fixing to a suspension device. Further, in use, the outer race 2 is supported by a knuckle (not shown) constituting a suspension device and does not rotate.

  The hub 3 is formed by combining a hub body 6 and an inner ring 7, and has double rows of inner ring tracks 8 a and 8 b on the outer peripheral surface, and is supported concentrically with the outer ring 2 on the inner diameter side of the outer ring 2. I have. Specifically, the inner raceway 8a of the axially outer row is directly formed at the axially intermediate portion of the outer peripheral surface of the hub main body 6, and the axially inner end (the inner side in the axial direction is attached to the suspension device). In the state, a side closer to the center in the width direction of the vehicle body, and conversely, “outside in the axial direction” refers to a side closer to the outer side in the width direction of the vehicle body.The same applies throughout the specification and the claims.) The inner ring 7 having the inner ring raceway 8b of the inner row in the axial direction formed on the outer peripheral surface of the small-diameter step portion 9 is fixedly fitted. The axially inner end face of the inner race 7 is suppressed by a caulking portion 10 formed by plastically deforming the inner end of the hub body 6 in the axial direction radially outward. A rotating flange 11 for supporting (coupling and fixing) the wheel is provided at a portion of the hub 3 that protrudes axially outward from an axial outer end opening of the outer race 2 at the axial outer end. Provided.

A plurality of rolling elements 12, 12 are provided between the outer raceways 4a, 4b and the inner raceways 8a, 8b, respectively, and the hub 3 is rotatable on the inner diameter side of the outer race 2. I support it.
An encoder 13 is externally fitted and fixed to a portion of the outer peripheral surface of the inner race 7 at the axially inner end which is deviated axially inward from the inner raceway 8b.
In addition, a seal ring 14 is provided between the axially outer end opening of the outer ring 2 and the outer peripheral surface of the axially intermediate portion of the hub body 6, and a cap 16 is attached to the axially inner end opening of the outer ring 2. Is installed. Thereby, the axially opposite ends of the space 15 in which the rolling elements 12 and 12 and the encoder 13 are installed are closed, and the grease sealed in the space 15 leaks to the external space or exists in the external space. Foreign matter is prevented from entering the space 15.

  The cap 16 has a bottomed cylindrical cap body 17 made by injection-molding a synthetic resin, and a fitting core formed by press-molding a non-magnetic metal plate into an L-shaped cross-section as a whole. And gold 18. The cap body 17 includes a cap cylindrical portion 19 and a cap bottom portion 20 which closes an axial inner end opening of the cap cylindrical portion 19. The fitting core 18 is fixed (molded) to the inner diameter side portion of the axially outer end portion (tip portion) of the cap cylindrical portion 19 among them. At the radially inner end of the axially outer end surface of the cap cylindrical portion 19, a sealing groove 21 having an axially open outer side and a radially inner side is formed over the entire circumference. An O-ring 22 is locked in the sealing groove 21.

At the radially outward portion of the cap bottom portion 20, there is provided a mounting portion 23 which bulges inward in the axial direction (has a larger axial thickness) than other portions. A through hole 24 penetrating in the axial direction is formed in a portion of the mounting portion 23 that faces the detection surface of the encoder 13 in the axial direction. A sensor (not shown) is assembled in the through hole 24. Further, a mounting nut 25 having an internal thread formed on an inner peripheral surface is embedded in a portion of the mounting portion 23 that is separated from the through hole 24 by insert molding.
The cap 16 having the above-described configuration fits the outer half portion of the fitting core 18 in the axial direction by press-fitting (in a tight fit) the inner peripheral surface of the inner end portion of the outer race 2 from the inside in the axial direction. At the same time, the cap cylindrical portion 19 constituting the cap main body 17 is assembled to the outer race 2 in a state where the axial outer end surface is in contact with the axial inner end surface of the outer race 2.

  According to the wheel supporting rolling bearing unit 1 having the above-described structure, the wheels fixed to the hub 3 can be rotatably supported by the suspension device supporting the outer ring 2. When the hub 3 and the encoder 13 rotate together with the wheels, the vicinity of the detection unit of the sensor facing the detection surface of the encoder 13 is changed to the N pole and the S pole existing on the detection surface of the encoder 13. Pass alternately. As a result, the direction of the magnetic flux flowing in the magnetic detecting element constituting the sensor changes alternately, and the characteristics of the magnetic detecting element change alternately. Since the frequency at which the characteristic of the magnetic sensing element changes is proportional to the rotation speed of the hub 3, if the output signal of the sensor is sent to a controller (not shown), the ABS and TCS can be appropriately controlled.

However, in the case of the above-described conventional structure, the following problem may occur.
That is, in the case of the conventional structure, if the radial thickness of a portion of the cap cylindrical portion 19 that is present on the radially outer side of the axial inner half of the fitting core 18 is large, Due to the molding shrinkage (shrinkage due to solidification), the inner half of the fitting core 18 in the axial direction receives compressive stress (radial inward force). Based on such compressive stress, when the fitting core 18 is deformed (tapered) such that the outer diameter increases toward the outside in the axial direction, the fitting core 18 is moved to the shaft of the outer ring 2. There is a possibility that it becomes difficult to press-fit into the inner peripheral surface of the inner end portion in the direction.
When the cap main body 17 is made of a crystalline resin, the cap main body 17 exists outside the radially inner half portion of the fitting core 18 in the cap cylindrical portion 19 with the rise in temperature during use. When the crystallization of the portion to be advanced proceeds, the portion shrinks, the interference of the fitting portion between the fitting core 18 and the outer ring 2 decreases, and the fitting force of this fitting portion may decrease. .
If the crystallinity of the portion of the cap cylindrical portion 19 existing radially outward of the axially inner half of the fitting core 18 is not uniform in the circumferential direction, the temperature during use is reduced. With the rise, the cap cylindrical portion 19 is warped, so that an axial gap is easily generated between the axial outer end surface of the cap cylindrical portion 19 and the axial inner end surface of the outer ring 2. There is a possibility that water may enter from a gap or an air gap (interval) existing between the detection surface of the encoder and the detection unit of the sensor may fluctuate, thereby lowering the detection accuracy of the sensor. .

JP 2015-152121 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has been made to realize a rolling bearing unit for supporting a wheel, which can prevent a decrease in assemblability of a cap and can sufficiently secure a seal during use.

The rolling bearing unit for supporting a wheel according to the present invention includes an outer ring, a hub, a plurality of rolling elements, and a cap.
The outer ring has a double-row outer ring raceway on the inner peripheral surface and does not rotate during use.
The hub has a double-row inner ring raceway on the outer peripheral surface, is supported concentrically with the outer ring on the inner diameter side of the outer ring, and protrudes axially outward from the axially outer end of the outer ring on the outer peripheral surface. A rotation side flange for supporting the wheel is provided at the portion.
Each of the rolling elements is provided between the outer raceway and the inner raceway so as to be able to roll a plurality of rolling bodies for each row.
The cap is for closing an axial inner end opening of the outer ring.
Such a cap includes a metal fitting core and a cap body made of synthetic resin.
Among these, the fitting core metal has an inner diameter side cylindrical portion, an outward flange portion formed to extend radially outward from an axial inner end portion of the inner diameter side cylindrical portion, and a diameter of the outward flange portion. An outer diameter side cylindrical portion formed in a state of extending outward in the axial direction from the outer end portion in the axial direction, and a part of the inner diameter side cylindrical portion located on the outer side in the axial direction is formed inside the outer ring in the axial direction. It is a fitting portion for fitting the end to the inside by interference fitting.
The cap main body covers an outer peripheral surface of a portion of the inner diameter side cylindrical portion located inward in the axial direction from the fitting portion of the inner diameter side cylindrical portion by a radially outer end portion, and the outward flange portion and the outer diameter side cylindrical portion. Is embedded and fixed to the fitting core bar.
Then, the cap fits the fitting portion of the fitting core into the axial inner end of the outer race by interference fit, and the inner diameter side cylinder of the fitting core in the cap body. The outer ring is attached to the outer race in a state where the axially outer surface of a portion located radially outward from the portion is in contact with the axial inner end surface of the outer race.

  In the case where the present invention is carried out, preferably, for example, a configuration in which the cap body is made of a crystalline resin can be adopted as in the invention described in claim 2.

ADVANTAGE OF THE INVENTION According to this invention comprised as mentioned above, while preventing the fall of the assemblability of a cap, the sealing property at the time of use can fully be ensured.
First, the reason why the assemblability of the cap can be prevented from being lowered is that, in the case of the present invention, the outer diameter side cylindrical portion is provided on the fitting core metal constituting the cap. That is, in the case of the present invention, the outer diameter side cylindrical portion is provided so as to extend axially outward from the radially outer end of the outward flange portion forming the fitting core. For this reason, the portion of the cap main body that is aligned with the outer diameter side cylindrical portion in the axial direction is, by the outer diameter side cylindrical portion, the same as the portion existing on the inner diameter side of the outer diameter side cylindrical portion. It can be divided into a part existing on the radial side. Therefore, a portion of the cap body that exerts a compressive stress (radial inward force) on the inner diameter side cylindrical portion based on molding shrinkage (shrinkage due to solidification) (the outer diameter side portion of the cap main body). The thickness dimension in the radial direction of the portion radially inside the cylindrical portion and radially outside the axially inner end portion of the inner diameter side cylindrical portion) when the outer diameter side cylindrical portion does not exist Smaller than. As a result, the fitting core metal is less likely to be deformed in a tapered shape based on the molding shrinkage, so that the assembling property when the inner diameter side cylindrical portion is internally fitted and fixed to the inner peripheral surface in the axially inner end portion of the outer ring. Drop can be prevented.

  In addition, the reason why the sealing performance can be sufficiently ensured is that the outer diameter side cylindrical portion is provided in the fitting core metal constituting the cap. That is, as described above, in the case of the present invention, a portion of the cap main body that is aligned with the outer diameter side cylindrical portion in the axial direction can be radially divided by the outer diameter side cylindrical portion. Therefore, based on thermal deformation during use, a portion that applies a radially inward force to the inner diameter side cylindrical portion of the fitting core (the inner radial direction of the outer diameter side cylindrical portion of the cap main body) The thickness dimension in the radial direction of the portion (existing radially outside the inner end portion in the axial direction of the inner diameter side cylindrical portion) is smaller than when the outer diameter side cylindrical portion is not present. As a result, the fitting core is affected by the thermal deformation of the cap body, so that the interference of the fitting part between the fitting core and the outer ring decreases, and the fitting force of the fitting part decreases. Things can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the 1st example of embodiment of this invention and which shows the rolling bearing unit for wheel support. The figure similar to FIG. 1 which shows the same 2nd example. The figure similar to FIG. 1 which shows the same 3rd example. Sectional drawing which shows the rolling bearing unit for wheel support of a conventional structure.

[First Example of Embodiment]
A first example of an embodiment of the present invention will be described with reference to FIG.
The rolling bearing unit 1a for supporting a wheel of the present embodiment includes an outer ring 2, a hub 3, a plurality of rolling elements 12, 12, an encoder 13, a seal ring 14, and a cap 16a.
The outer race 2 has a double-row outer raceway 4a, 4b on the inner peripheral surface and a stationary flange 5 on the outer peripheral surface for coupling and fixing to a suspension device. In use, the outer ring 2 is supported (coupled and fixed) by a knuckle (not shown) constituting a suspension device and does not rotate.

  The hub 3 is formed by combining a hub body 6 and an inner ring 7, and has double rows of inner ring tracks 8 a and 8 b on the outer peripheral surface, and is supported concentrically with the outer ring 2 on the inner diameter side of the outer ring 2. I have. Specifically, the inner ring raceway 8a of the axially outer row is directly formed at the axially intermediate portion of the outer peripheral surface of the hub body 6, and the small-diameter stepped portion 9 also formed at the portion near the inner end in the axial direction has the outer peripheral surface. The inner race 7 having an inner race 8b formed in the inner row in the axial direction is externally fitted and fixed. The axially inner end face of the inner race 7 is suppressed by a caulking portion 10 formed by plastically deforming the inner end of the hub body 6 in the axial direction radially outward. A rotating flange 11 for supporting (coupling and fixing) a wheel is provided at a portion of the hub body 6 at the axial outer end protruding axially outward from the axial outer end opening of the outer ring 2. Is provided.

  Each of the rolling elements 12, 12 is provided between the outer raceways 4a, 4b and the inner raceways 8a, 8b so as to be capable of rolling in a plurality of rows.

  Further, the encoder 13 is externally fitted and fixed to a portion of the outer peripheral surface of the inner ring 7 which is axially inward from the inner raceway 8b at an inner end in the axial direction. The encoder 13 is formed by combining a support ring 26 formed of a magnetic metal plate with a substantially L-shaped cross section in a ring shape as a whole, and an encoder body 28 attached to a side surface of a circular ring portion 27 constituting the support ring 26. . The encoder body 28 is formed in a ring shape entirely by a permanent magnet such as a rubber magnet mixed with ferrite powder. The encoder body 28 is magnetized in the axial direction, and the direction of the magnetization is alternately and equally arranged in the circumferential direction. It changes with pitch. Therefore, S poles and N poles are alternately arranged at an equal pitch on the axially inner side surface, which is the surface to be detected, of the encoder body 28.

The seal ring 14 is provided between the axially outer end opening of the outer ring 2 and the outer peripheral surface of the hub body 6 at the axially intermediate portion.
On the other hand, the cap 16a is attached to the axial inner end opening of the outer race 2 in a state of closing the axial inner end opening.
In this way, the axially opposite openings of the space 15 in which the rolling elements 12 and 12 and the encoder 13 are installed are closed, and the grease sealed in the space 15 leaks to the external space, or Preventing the existing foreign matter from entering the space 15 is prevented.

The cap 16a includes a substantially disk-shaped cap body 17a made by injection molding a crystalline resin, and a fitting core 18a made by press-molding a metal plate such as a steel plate. Have been.
The cap body 17a is a substantially disc-shaped member, and has a sealing groove 21a that is open only on the outside in the axial direction over the entire circumference at a portion near the radially outer end of the outer surface in the axial direction. An O-ring 22a is locked in the sealing groove 21a.
A mounting portion 23a bulging inward in the axial direction (having a larger axial thickness) than other portions is provided at a radially central portion and a circumferential portion of the intermediate portion of the cap body 17a. Is provided. A through hole 24 penetrating in the axial direction is formed in a portion of the mounting portion 23a that faces the detection surface of the encoder 13 (encoder main body 28) in the axial direction. In the through hole 24, a sensor constituting a sensor unit (not shown) is assembled. Further, a mounting nut 25 having an internal thread formed on the inner peripheral surface is embedded in a portion of the mounting portion 23a that is separated from the through hole 24 by insert molding.

In particular, in the rolling bearing unit 1a for supporting a wheel according to the present embodiment, the fitting core bar 18a includes an inner diameter side cylindrical portion 29, an outward flange portion 30, and an outer diameter side cylindrical portion 31.
Of these, the inner diameter side cylindrical portion 29 corresponds to the inner diameter side cylindrical portion in the claims, and is formed in a cylindrical shape in which the outer diameter size and the inner diameter size do not change over the entire length in the axial direction. . The axially intermediate portion or the axially inner edge of such an inner diameter side cylindrical portion 29 is embedded (molded) by insert molding in a portion near the radially outer end of the cap body 17a. On the other hand, an axial middle portion or an axial outer end edge of the inner diameter side cylindrical portion 29 protrudes (exposes) axially outward from the cap body 17a.

  The outward flange portion 30 has a ring shape and is formed so as to extend (bend) radially outward from an axially inner end of the inner cylindrical portion 29. Such outward flange portion 30 is also embedded (molded) in a portion near the radially outer end of the cap body 17a by insert molding. In this embedded state, the outer diameter of the outward flange 30 is smaller than the outer diameter of a portion of the cap body 17a that matches the outward flange 30 in the axial direction. Stated another way, the radially outer edge of the outward flange 30 is located radially inward of the outer peripheral surface of a portion of the cap body 17a that is aligned with the outward flange 30 in the axial direction. ing. The radially outer edge of the outward flange 30 is located radially outward of the radially outer edge of the sealing groove 21a.

  The outer diameter side cylindrical portion 31 corresponds to the outer diameter side cylindrical portion described in the claims, and is formed in a cylindrical shape. Such an outer diameter side cylindrical portion 31 is formed in a state of being extended (bent) outwardly in the axial direction from a radially outer end of the outward flange portion 30. Such an outer diameter side cylindrical portion 31 is also embedded (molded) by insert molding in a portion near the radially outer end of the cap body 17a. The position in the axial direction of the axially outer edge of the outer diameter side cylindrical portion 31 may be located outside the outward flange portion 30 in the axial direction. Preferably, the axial position of the outer peripheral edge of the outer diameter side cylindrical portion 31 is aligned with the axial inner edge of the sealing groove 21a, or the axis of the sealing groove 21a. It is located axially outside the inner edge in the direction. Also, preferably, the axial position of the outer edge of the outer cylindrical portion 31 in the axial direction is aligned with the outer cylindrical portion 31 in the radial direction of the axially outer surface of the cap body 17a. Position it axially inward from the position. Specifically, in the case of the present example, the axial position of the outer end of the outer diameter side cylindrical portion 31 in the axial direction coincides with the inner end of the groove 21a in the axial direction. The inner diameter of the outer diameter side cylindrical portion 31 is larger than the inner diameter of the radial outer edge of the sealing groove 21a. On the other hand, the outer diameter of the outer diameter side cylindrical portion 31 is smaller than the outer diameter of a portion of the cap body 17a that is aligned with the outer diameter side cylindrical portion 31 in the axial direction. Stated another way, the inner peripheral surface of the outer diameter side cylindrical portion 31 is located radially outward from the radially outer end edge of the sealing groove 21a, and the outer diameter side cylindrical portion 31 Is located radially inward of the outer circumferential surface of a portion of the cap body 17a that matches the outer diameter side cylindrical portion 31 in the axial direction. In this state, the portion of the cap body 17a that is aligned with the outer diameter side cylindrical portion 31 in the axial direction is formed by the outer diameter side cylindrical portion 31 with the inner diameter side resin portion 32 and the outer diameter side resin portion 33. Is divided into Specifically, the inner diameter side resin portion 32 is a portion of the cap body 17a that is aligned with the outer diameter side cylindrical portion 31 in the axial direction, and the outer peripheral surface of the inner diameter side cylindrical portion 29 and the outer diameter It is constituted by a cylindrical portion existing between the side cylindrical portion 31 and the inner peripheral surface. On the other hand, the outer diameter side resin portion 33 is a portion of the cap body 17a which is aligned with the outer diameter side cylindrical portion 31 in the axial direction, and is located on the outer diameter side with respect to the outer peripheral surface of the outer diameter side cylindrical portion 31. It is constituted by existing cylindrical parts.

  The cap 16a having the above configuration fits the axially intermediate portion or the axially outer end edge of the inner diameter side cylindrical portion 29 of the fitting core 18a to the inner peripheral surface of the axially inner end portion of the outer race 2. In addition, a portion of the axially outer surface of the cap body 17a, which is located radially outside of the inner cylindrical portion 29, is brought into contact with the axially inner end surface of the outer ring 2, and the outer ring The second axially outer end opening is closed.

According to the rolling bearing unit 1a for wheel support according to the present embodiment having the above-described configuration, it is possible to prevent a decrease in the assemblability of the cap 16a and sufficiently secure the sealing performance.
First, the reason why the lowering of the assemblability of the cap 16a can be prevented is that in the case of the structure of the present example, the outer diameter side cylindrical portion 31 is provided on the fitting core 18a constituting the cap 16a. . That is, in the case of this example, the position of the axially outer edge of the outer diameter side cylindrical portion 31 is made to coincide with the axially inner edge of the sealing groove 21a. Therefore, a portion of the cap main body 17a that is radially outside the axially inner end of the inner diameter side cylindrical portion 29 and that is aligned with the outer diameter side cylindrical portion 31 in the axial direction is this portion. The outer diameter side cylindrical portion 31 is divided into the inner diameter side resin portion 32 and the outer diameter side resin portion 33. In the cap main body 17a, a portion that is aligned with the sealing groove 21a in the axial direction is a portion that exists radially outside the sealing groove 21a, and a portion that also exists radially inside the sealing groove 21a. Is divided into In other words, in the case of this example, in the cap main body 17a, a portion of the cap main body 17a existing radially outside the inner diameter side cylindrical portion 29 is provided from the outer peripheral surface of the inner diameter side cylindrical portion 29 to the cap main body 17a. There is no continuous part up to the outer peripheral surface of the. Therefore, based on the molding shrinkage (shrinkage due to solidification), a portion (the inner diameter side resin portion 32 and the inner diameter side resin portion 32) that applies a compressive stress (radial inward force) to the axial inner end of the inner diameter side cylindrical portion 29 The portion of the cap body 17a that is aligned with the sealing groove 21a in the axial direction and that is located radially inward of the sealing groove 21a) has a thickness dimension in the radial direction that is larger than the outer thickness. It is smaller than when the radial side cylindrical portion 31 does not exist (when it is not divided into the inner diameter side resin portion 32 and the outer diameter side resin portion 33). As a result, the inner diameter side cylindrical portion 29 is less likely to be deformed in a tapered shape based on the molding shrinkage. Therefore, when the inner diameter side cylindrical portion 29 is internally fitted and fixed to the inner peripheral surface of the outer ring 2 in the axial direction inner end portion. Can be prevented from decreasing.

  The reason why the sealing performance can be sufficiently ensured is also because the outer diameter side cylindrical portion 31 is provided on the fitting core metal 18a constituting the cap 16a. That is, as described above, in the case of the present example, the portion of the cap body 17a that is located radially outside the inner end in the axial direction of the inner cylindrical portion 29 is outside the inner resin portion 32. It is divided into a radial resin part 33. For this reason, even when the inner diameter side resin portion 32 is crystallized with the temperature rise during use and the inner diameter side resin portion 32 is thermally contracted, the outer diameter side cylindrical portion 31 is not formed. (In a case where a portion existing radially outside of the inner end portion in the axial direction of the inner diameter side cylindrical portion 29 is not divided into the inner diameter side resin portion 32 and the outer diameter side resin portion 33). The compressive stress acting on the inner cylindrical portion 29 is reduced. As a result, the interference of the outer fitting portion between the inner peripheral surface of the inner end portion in the axial direction of the outer ring 2 and the inner cylindrical portion 29 can be reduced, and the fitting force of the fitting portion can be prevented from being reduced.

  Further, even when the crystallinity of the inner resin portion 32 of the cap body 17a is not uniform in the circumferential direction, the influence of shrinkage due to the crystallization of the inner resin portion 32 due to the temperature rise during use. Since there is no effect on the portion of the cap body 17a other than the inner-diameter resin portion 32, the cap body 17a is warped, and the radially outer end of the axially outer surface of the cap body 17a. A gap in the axial direction can be prevented from being formed between the outer ring 2 and the inner end face in the axial direction of the outer ring 2. As a result, the sealing performance of the cap 16a can be improved.

[Second Example of Embodiment]
A second example of the embodiment of the present invention will be described with reference to FIG.
In the case of the wheel supporting rolling bearing unit 1b of the present example, the structure of the fitting core 18b constituting the cap 16b is different from that of the first example of the above-described embodiment.
Specifically, in the case of the present example, the inner diameter side cylindrical portion 29a constituting the fitting core 18b is formed by a large diameter cylindrical portion 34 formed at an axial middle portion or an axial outer end edge, A small-diameter cylindrical portion 35 provided axially inward of the portion 34 and a continuous step portion 36 that connects the large-diameter cylindrical portion 34 and the small-diameter cylindrical portion 35 to each other.

  The large-diameter cylindrical portion 34 is a portion that is fitted into the inner peripheral surface of the outer ring 2 by press-fitting (by interference fitting) from the inside in the axial direction in the assembled state. It is formed in a cylindrical shape whose inner diameter and outer diameter do not change.

  The small diameter cylindrical portion 35 is formed in a cylindrical shape whose inner diameter and outer diameter do not change in the axial direction. Such a small-diameter cylindrical portion 35 has an inner diameter smaller than the inner diameter of the large-diameter cylindrical portion 34 and an outer diameter smaller than the outer diameter of the large-diameter cylindrical portion 34. ing.

The continuous step portion 36 is formed in a state where the axial inner edge of the large-diameter cylindrical portion 34 and the axial outer edge of the small-diameter cylindrical portion 35 are continuous. Such a continuous step portion 36 has a conical cylindrical shape whose outer diameter becomes smaller toward the inner side in the axial direction. The continuous step should be present on an imaginary plane existing in a direction orthogonal to the center axis of the hub 3 (formed in a circular shape perpendicular to the large-diameter cylindrical portion 34 and the small-diameter cylindrical portion 35). You can also.
Further, in the case of this example, an outward flange portion 30a is formed so as to extend radially outward from the axially inner end of the small-diameter cylindrical portion 35. In such an outward flange portion 30a, a difference between an outer diameter dimension and an inner diameter dimension is larger than the outward flange portion 30 of the first example of the above-described embodiment.

According to such a structure of the present example, because it has provided the continuous stepped portion 36 and the small-diameter cylindrical portion 35 on the inner diameter side cylindrical portion 29a, to form a sealing recessed groove 21a formed in the cap body 17a Space can be easily secured. Further, the rigidity of the inner diameter side cylindrical portion 29a in the radial direction can be increased. In addition, the portion that deforms (deforms in a tapered shape) based on the molding shrinkage (shrinkage due to solidification) of the cap body 17a is limited to the small-diameter cylindrical portion 35 to suppress the deformation of the large-diameter cylindrical portion 34. Can be. Therefore, it is possible to prevent a decrease in assemblability when the large-diameter cylindrical portion 34 is internally fitted and fixed to the inner peripheral surface of the outer race 2 at the axially inner end. In the case of the structure of this example, since the position of the small-diameter cylindrical portion 35 and the encoder 13 are close to each other, the fitting core 18b is made of, for example, a nonmagnetic metal plate such as an austenitic stainless steel plate. Is preferred.
Other structures, operations, and effects are the same as those of the first embodiment described above.

[Third Example of Embodiment]
A third example of the embodiment of the present invention will be described with reference to FIG.
Also in the case of the wheel supporting rolling bearing unit 1c of the present example, the structure of the fitting core 18c that forms the cap 16c is different from those of the first and second examples of the above-described embodiment. The structures of the inner diameter side cylindrical portion 29a and the outward flange portion 30a constituting the fitting core 18c are the same as those in the second example of the above-described embodiment.

In the case of this example, the axially outer end of the outer diameter side cylindrical portion 31a formed in a state of extending outward in the axial direction from the radially outer end of the outward flange portion 30a is the first outer end of the above-described embodiment. It is located outside in the axial direction than in the case of the example and the second example. Specifically, the axially outer end edge of the outer diameter side cylindrical portion 31a is axially outward from the axially central position of the sealing groove 21a and the radially outer surface of the cap body 17a. With respect to the direction, it is located axially inward of a portion that matches the outer diameter side cylindrical portion 31a.
In the case of the present example, cutouts 37, 37 having radially open ends and axially outer sides are formed at a plurality of positions in the circumferential direction on the axially outer end surface of the outer diameter side cylindrical portion 31a. In the case of this example, the axial position of the bottom (axial inner end face) of each of the cutouts 37 is matched with the axial inner edge (bottom) of the sealing groove 21a.

Such notches 37, 37 are formed by punching a plurality of radially outer ends of a ring-shaped material serving as a material of the fitting core 18c in a circumferential direction, respectively, into a rectangular shape. Then, the fitting cored bar 18c is formed by pressing the petal-shaped intermediate material having the cutouts 37, 37 formed in this way.
In the case of such a structure of this example, it is possible to improve the flow of the synthetic resin into the portion corresponding to the inner diameter side resin portion 32 during insert molding. In addition, in order to further improve the wraparound of the synthetic resin into the portion corresponding to the inner diameter side resin portion 32 during insert molding, the outer flange portion 30a is inserted through the outer flange portion 30a in the axial direction. Alternatively, a configuration in which a plurality of through holes are formed may be employed. Such a through hole can also be formed by punching before press working, similarly to the notches 37, 37 as described above.

  The present invention can also be implemented by appropriately combining the structures of the above-described embodiments.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c Rolling bearing unit for wheel support 2 Outer ring 3 Hub 4a, 4b Outer ring track 5 Stationary side flange 6 Hub body 7 Inner ring 8a, 8b Inner ring track 9 Small diameter step portion 10 Caulking portion 11 Rotating side flange 12 Rolling element 13 Encoder 14 Seal ring 15 Space 16, 16a, 16b, 16c Cap 17, 17a Cap body 18, 18a, 18b, 18c Fitting core 19 Cap cylinder 20 Cap bottom 21, 21a Sealing groove 22, 22a O-ring 23, 23a mounting portion 24 through hole 25 mounting nut 26 support ring 27 circular ring portion 28 encoder body 29, 29a inner diameter side cylindrical portion 30, 30a outward flange portion 31, 31a outer diameter side cylindrical portion 32 inner diameter side resin portion 33 outer Diameter side resin part 34 Large diameter cylindrical part 35 Small diameter cylindrical part 36 Continuous step part 37 Cut Notch

Claims (2)

An outer ring that has a double-row outer ring track on the inner peripheral surface and does not rotate even when used,
The outer peripheral surface has a double row of inner ring raceways, is supported concentrically with the outer ring on the inner diameter side of the outer ring, and has a wheel on a portion of the outer peripheral surface protruding axially outward from an axially outer end of the outer ring. A hub provided with a rotating flange for supporting the
A rolling element provided between the outer raceway and the inner raceway, and a plurality of rolling elements for each of two rows;
A cap for closing an axial inner end opening of the outer ring,
The cap includes a metal fitting core and a synthetic resin cap body,
The fitting metal core, and the inner diameter side cylindrical portion, and the outward flange portion formed in a state extending from the axially inner end portion of the inner diameter side cylindrical portion radially outward, the radially outer of the outward flange portion An outer diameter side cylindrical portion formed in a state of being extended outward in the axial direction from the end portion, and a part of the inner diameter side cylindrical portion located on the axially outer side is an axially inner end portion of the outer ring. It is a fitting part to fit inside with a tight fit on the
The cap main body covers an outer peripheral surface of a portion of the inner diameter side cylindrical portion located inward in the axial direction from the fitting portion of the inner diameter side cylindrical portion by a radially outer end portion, and the outward flange portion and the outer diameter side cylindrical portion. Is embedded and fixed to the fitting core bar,
The cap fits the fitting portion of the fitting core into the axial inner end of the outer ring by interference fitting, and further includes, from the cap body, the inner diameter side cylindrical portion of the fitting core. A rolling bearing unit for supporting a wheel mounted on an outer race in a state where an axially outer surface of a portion located radially outward is in contact with an axially inner end surface of the outer race. The rolling bearing unit for supporting wheels according to claim 1, wherein the cap body is made of a crystalline resin.

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