JP2016041949A - Wheel supporting rolling bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wheel supporting rolling bearing unit which is constructed to prevent a cover from falling off one end in the axial direction of an outer ring when temperature rise in an internal space existing on the inner-diameter side of the outer ring involves pressure rise in the internal space.SOLUTION: In a cylindrical part 17a of a cover 16a at its axial intermediate portion located below a vehicle with respect to the circumferential direction in the state that a wheel supporting rolling bearing unit 1b is assembled on the vehicle, a vent hole 23 is provided while passing through the cylindrical part 17a in the radial direction. A seal lip 26 of a seal material 25 provided at the front end of the cylindrical part 17a is put in slide contact with the outer peripheral face of a shoulder part 28 of an inner ring 11 throughout its periphery. An axial distance L from the axial inner edge of the outer peripheral face of the shoulder part 28 to a slide contact area between the front edge of the seal lip 26 and the outer peripheral face of the shoulder part 28 is set longer than an axial distance d from the axial inner edge of the inner peripheral face of a knuckle pilot part 20 to an opening of the vent hole 23 (L>d).SELECTED DRAWING: Figure 2

Description

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

  The wheel (driven wheel) of the automobile is supported rotatably with respect to the suspension device by a wheel bearing rolling bearing unit 1 as shown in FIG. 6, for example. This wheel-supporting rolling bearing unit 1 is configured such that a hub 3 is rotatably supported via a plurality of rolling elements 4 and 4 on the inner diameter side of an outer ring 2. Of these, the outer ring 2 is provided with a stationary side flange 5 for supporting and fixing to the suspension device on the outer peripheral surface, and double row outer ring raceways 6a and 6b on the inner peripheral surface. Further, the hub 3 is provided with double row inner ring raceways 7a and 7b on the outer peripheral surface and a rotation side flange 8 for supporting and fixing a rotor constituting a wheel and a disc brake. The rolling elements 4 and 4 are held by the cages 9 and 9 between the outer ring raceways 6a and 6b and the inner ring raceways 7a and 7b. It is provided so that it can roll freely. In the example shown in the drawing, balls are used as the rolling elements 4 and 4. However, in the case of a rolling bearing unit for supporting a wheel of an automobile with a heavy weight, a tapered roller may be used as each rolling element. is there.

  The hub 3 is formed by coupling and fixing a hub body 10 and an inner ring 11. Of these, the hub body 10 is a portion near the outer end in the axial direction (outside with respect to the axial direction means the side that is the outer side in the width direction of the vehicle body when assembled to the suspension device, and is the left side of each figure. On the other hand, the right side of each figure, which is the center side in the width direction of the vehicle body, is referred to as the inside in the axial direction (the same applies throughout the present specification and claims). The inner ring raceway 7a on the outer side in the axial direction of the inner ring raceways 7a and 7b is provided in the part, and the small-diameter step portion 12 is provided on the portion closer to the inner end in the axial direction. Further, the inner ring 11 is provided with an inner ring raceway 7b on the outer peripheral surface on the inner side in the axial direction of the inner ring raceways 7a and 7b. Such an inner ring 11 is in a state of being fitted and fixed to the small-diameter step portion 12 of the hub main body 10, and a caulking portion 13 in which the axial inner end surface of the inner ring 11 is formed at the axial inner end portion of the hub main body 10. The hub body 10 is coupled and fixed to the hub body 10.

  Further, a seal ring 14 is mounted between the inner peripheral surface of the outer end of the outer ring 2 in the axial direction and the outer peripheral surface of the intermediate portion of the hub 3 in the axial direction. It exists between the outer peripheral surfaces and closes the axially outer opening of the rolling element installation space 15 provided with the rolling elements 4, 4. Further, the axially inner opening of the outer ring 2 is closed by a cover 16. The cover 16 is formed by subjecting a metal plate such as a steel plate to plastic processing such as drawing, and the entire inner portion of the cylindrical portion 17 is covered by a bottom plate portion 18 having a truncated cone shape. It has a bottom cylindrical shape. Further, a flange portion 19 formed by buckling deformation of the metal plate radially outward is provided at the inner end portion in the axial direction of the cylindrical portion 17. Such a cover 16 is fitted into the inner peripheral surface of the knuckle pilot portion 20 provided on the inner end in the axial direction of the outer ring 2 by an interference fit, and the outer side surface in the axial direction of the flange portion 19. Is fixed to the inner end portion in the axial direction of the outer ring 2 in a state where it is abutted against the inner end surface in the axial direction of the knuckle pilot portion 20.

By the way, in the case of the wheel support rolling bearing unit 1 as described above, when the amount of heat generated by the rotor constituting the disc brake increases, for example, by using a large amount of brakes or suddenly braking while traveling downhill, Heat is transmitted to the rotation side flange 8 and exists on the inner diameter side of the outer ring 2 (enclosed by the inner peripheral surface of the outer ring 2, the outer peripheral surface of the hub 3, the seal ring 14 and the cover 16). In addition, the temperature in the internal space 21 (including the rolling element installation space 15) rises. As a result, the pressure (air pressure) in the internal space 21 increases. When the pressure in the internal space 21 rises significantly, the cover 16 is displaced in the direction (axially inward) of coming out of the inner end of the outer ring 2 in the axial direction (knuckle pilot part 20). There is a possibility that the outer ring 2 may fall out (drop off) from the inner end in the axial direction. This tendency is described in, for example, Patent Document 1, as shown in FIG. 7, compared with the wheel support rolling bearing unit 1a in which the hub main body 10a and the inner ring 11a are coupled and fixed by the nut 22, as shown in the above-described figure. As shown in FIG. 6, in the case of the wheel bearing rolling bearing unit 1 in which the hub main body 10 and the inner ring 11 are coupled and fixed by the caulking portion 13, the volume of the internal space 21 becomes large, which becomes remarkable.
In order to reduce the volume of the internal space, it is conceivable to reduce the axial length of the knuckle pilot portion provided at the inner end portion in the axial direction of the outer ring (for example, to be positioned outside the caulking portion in the axial direction). It is done. However, depending on the vehicle model, it may be difficult to keep the axial length of the knuckle pilot portion short. Moreover, the fitting force of the cover may be reduced. In order to prevent the cover from falling off, it is also conceivable to increase the tightening margin for the knuckle pilot portion of the cylindrical portion constituting the cover. However, in this case, the press-fitting work of the cover into the knuckle pilot portion becomes troublesome. Further, at the time of press-fitting, there is a possibility that damage such as scratches may occur in the cylindrical portion or knuckle pilot portion, or deformation or the like may occur in this cylindrical portion.

JP-A-10-196661

  In view of the circumstances as described above, the present invention provides a wheel support that can prevent the cover from dropping off from one end of the outer ring in the axial direction even when the pressure in the inner space increases as the temperature of the inner space increases. It was invented to realize the structure of the rolling bearing unit for use.

The wheel bearing rolling bearing unit of the present invention includes an outer ring, a hub, a plurality of rolling elements, and a cover.
Among these, 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, and rotates with the wheel when in use.
Further, a plurality of rolling elements are provided between the outer ring raceways and the inner ring raceways so as to freely roll.
Further, the cover includes a cylindrical portion fitted on the inner peripheral surface of the axially inner end portion of the outer ring, and a bottom plate portion that hermetically closes the axially inner opening of the cylindrical portion.
In particular, in the rolling bearing unit for supporting a wheel of the present invention, there is provided a sealing means for closing the axially inner opening of the rolling element installation space existing between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub. Yes. At the same time, an opening on the outer diameter side is closed by the outer ring while the cover is fixed at a regular position at the axially outer end portion or intermediate portion of the cylindrical portion. When displaced inward in the direction, an air passage is provided for communicating the inner space and the outer space of the cover.
In addition, this ventilation path may be provided only in the outer end portion of the cylindrical portion, may be provided only in the intermediate portion, or may be provided in a range extending from the outer end portion to the intermediate portion.

  In the case of implementing the wheel bearing rolling bearing unit of the present invention as described above, preferably, as in the invention described in claim 2, the sealing means is the base end portion of the cylindrical portion in the axial direction outer end portion. The tip edge of the seal lip supported against the inner ring raceway is brought into sliding contact with the outer peripheral surface of the shoulder portion provided in the portion adjacent to the inner side in the axial direction of the inner ring raceway on the inner side in the axial direction. It consists of. Then, the axial distance from the axial inner end edge of the outer peripheral surface of the shoulder portion to the sliding contact portion between the tip edge of the seal lip and the outer peripheral surface of the shoulder portion is defined as the axial inner end portion of the outer ring. The axial distance from the inner end edge in the axial direction of the fitting portion to the cylindrical portion to the opening on the outer diameter side of the air passage is made larger.

  When carrying out the invention described in claim 2 as described above, specifically, for example, as in the invention described in claim 3, the sealing means is disposed on the inner peripheral surface of the outer ring. A seal composed of an annular cored bar that is fitted and fixed to an axially outer side part than the part fitted with the cylindrical part, and a sealing material having a seal lip that supports the base end part on the cored bar A ring. Further, a recess provided in a state where the air passage is opened at an axial outer end edge of the cylindrical portion in a range extending from an axial outer end portion to an intermediate portion of the outer peripheral surface of the cylindrical portion, and the cylindrical portion And a notch portion provided in a state where the radially inner end portion (bottom portion) of the recess and the inner peripheral surface of the cylindrical portion communicate with each other. The axial distance from the axial inner end edge of the outer peripheral surface of the shoulder portion to the sliding contact portion between the tip edge of the seal lip and the outer peripheral surface of the shoulder portion is defined as the axial inner end surface of the seal ring. From the axial distance between the axial outer end surface of the cylindrical portion and the axial inner end edge of the fitting portion between the axial inner end portion of the outer ring and the cylindrical portion to the axial inner end portion of the recess. Greater than the sum of the axial distances.

According to the rolling bearing unit for supporting a wheel of the present invention configured as described above, even when the pressure in the internal space rises with the temperature rise in the internal space where the axial inner end opening is closed by the cover, It is possible to prevent the cover from dropping off from the inner end in the axial direction of the outer ring.
That is, in the case of the present invention, when the temperature in the internal space rises and the cover is displaced in a direction (axially inward) that is pulled out from the axial inner end of the outer ring, the axial inner end of the outer ring Before the cover falls off, the internal space (the inner space of the cover) communicates with the external space (the outer space of the cover) through a ventilation path provided in the cylindrical portion of the cover. Further, in a state where the internal space and the external space communicate with each other through the air passage, air in the internal space is discharged to the external space. For this reason, it is possible to prevent the pressure in the internal space from rising further, and to prevent the cover from being further displaced inward in the axial direction and falling off from the axial inner end of the outer ring.

  Further, the internal space can be divided into an axially outer space (a rolling element installation space) and an axially inner space with the sealing means interposed therebetween. In this case, the temperature and pressure of the axially outer space are likely to increase compared to the axially inner space, but the area of the cover that receives the pressure of the axially outer space can be reduced. For this reason, the force for displacing the cover inward in the axial direction can be kept small. Further, air moves from the outer space in the axial direction to the inner space in the axial direction through the sealing means, and the amount of movement depends on the pressure difference between the outer space in the axial direction and the inner space. Since the pressure means can be moderated by providing the sealing means, it is difficult to remove the cover from this surface. Furthermore, since the axial inner space is sealed by providing the sealing means, the pressure drop accompanying the increase in the volume of the axial inner space when the cover moves inward in the axial direction becomes large. Also from this surface, the cover can be made difficult to drop off.

  According to the invention described in claim 2, even if the cover is displaced inward in the axial direction and the internal space and the external space communicate with each other through the air passage, the leading edge of the seal lip is removed. The inner ring can be kept in sliding contact with the outer peripheral surface of the shoulder portion of the inner ring. Accordingly, grease sealed in the rolling element installation space may leak to the outside from the axially inner opening of the outer ring, or foreign matter such as muddy water may enter the rolling element installation space from the axially inner opening of the outer ring. Can be more reliably prevented.

Sectional drawing which shows the 1st example of embodiment of this invention. The X section enlarged view of FIG. 1 similarly. FIG. 3 is a view similar to FIG. 2, showing the cover displaced inward in the axial direction. The figure similar to FIG. 2 which shows the 2nd example of embodiment of this invention. The figure similar to FIG. 2 which shows the 3rd example. Sectional drawing which shows the 1st example of the conventional structure of the rolling bearing unit for wheel support. Sectional drawing which shows the 2nd example.

[First example of embodiment]
1-3 show a first example of an embodiment of the present invention corresponding to claims 1 and 2. The feature of the present invention including this example is that the shaft of the outer ring 2 can be used even when the pressure of the internal space 21a rises as the temperature of the internal space 21a is blocked by the cover 16a. The cover 16a is structured to prevent the cover 16a from falling off from the inner end in the direction. The structure and operation of the other parts are the same as those of the conventionally known wheel support rolling bearing unit including the conventional structure shown in FIGS. For this reason, the explanation about the equivalent part is omitted or simplified, and hereinafter, the characteristic part of this example will be mainly described.

  In use, the wheel bearing rolling bearing unit 1b of the present example covers the axially inner opening of the outer ring 2 that is supported by the suspension device and does not rotate with the cover 16a. The cover 16a is formed into a bottomed cylindrical shape by subjecting a metal plate to plastic working such as drawing, and the cylindrical portion 17a and a bottom plate that hermetically closes the axially inner end of the cylindrical portion 17a. Part 18a. Of these, the cylindrical portion 17a is located below the vehicle in the circumferential direction with the wheel support rolling bearing unit 1b assembled to the vehicle (the stationary flange 5 of the outer ring 2 supported and fixed to the suspension device). A vent hole 23 corresponding to the vent path described in the claims is provided in an axially intermediate portion of the portion located in a state of penetrating the cylindrical portion 17a in the radial direction. In the case of this example, as shown in FIG. 2, the vent hole 23 is covered by the pilot portion 20 of the outer ring 2 with the cover 16a fixed at a regular position (on the outer diameter side). The opening is blocked). The shape and number of the vent holes 23 are not particularly limited. In the case of this example, the shape is a circular hole, and only one is provided as a whole. In addition, when providing two or more, the axial direction position may be made the same, and it may provide in the circumferential direction, and may provide it in the circumferential direction by shifting the axial direction position. However, when the position in the axial direction is shifted, the position of the opening of the vent hole that exists most inward in the axial direction is restricted as described later. Further, the bottom plate portion 18a has a circular flat plate shape (disk shape) in which at least the entire outer surface in the axial direction is flat (uneven portions are not formed). In the case of this example, the metal plate constituting the cover 16a is bent at a right angle outward from the axial inner end edge of the cylindrical portion 17a, and further folded back into a U shape (180 degrees). A flange portion 19a is provided in a state where the cylindrical portion 17a and the bottom plate portion 18a are continuous. Such a cover 16a fits the cylindrical portion 17a into the knuckle pilot portion 20 provided at the inner end portion in the axial direction of the outer ring 2 with an interference fit, and the outer side surface of the flange portion 19a in the axial direction. The knuckle pilot portion 20 is fixed to the knuckle pilot portion 20 in a state where positioning in the axial direction is achieved by abutting against the inner end face in the axial direction of the knuckle pilot portion 20.

  Further, in the case of this example, by drawing the inner end of the cylindrical portion 17a in the axial direction, the diameter (inner diameter and outer diameter) of the inner end in the axial direction is larger than the portion adjacent to the inner side in the axial direction. ) Is provided with a small diameter portion 24. Among the small-diameter portions 24, the front half (axially outer half) is provided with a small-diameter cylindrical portion 24a having a constant outer diameter in the axial direction, and the base half (axially inner half) is provided. Is provided with a tapered cylindrical portion 24b that is inclined in a direction in which the diameter increases toward the inner side in the axial direction. An annular sealing material 25 is provided over the entire circumference at the tip of the small diameter portion 24 (small diameter cylindrical portion 24a). The sealing material 25 is made of an elastic material such as an elastomer such as rubber, and is bonded and fixed to the small-diameter portion 24 of the cover 16 a by vulcanization adhesion, and includes two sealing lips 26 and 27. 1 and 2 show the shapes of these seal lips 26 and 27 in a free state. And among these seal lips 26 and 27, the seal lip 26 on the inner diameter side provided in a state protruding inward in the radial direction extends radially inward from the tip end portion of the small diameter portion 24, and The radially inner end portion is bent inward in the axial direction. And the front edge (diameter inner edge) of such a seal lip 26 is provided on the shoulder adjacent to the axially inner side of the inner ring raceway 7b on the axially inner side of the double row inner ring raceways 7a, 7b. The outer periphery of the portion 28 is in sliding contact with the entire periphery. In the case of this example, the axial inner end edge of the outer peripheral surface of the shoulder portion 28 (the cross-sectional shape existing at the continuous portion between the outer peripheral surface of the shoulder portion 28 and the axial inner end portion is a partial arc. The axial distance L from the tip edge of the seal lip 26 to the sliding contact portion of the outer peripheral surface of the shoulder portion 28 is defined as the inner peripheral surface of the knuckle pilot portion 20. The vent hole from the inner end edge in the axial direction (excluding the chamfered portion present in the continuous portion between the inner peripheral surface of the knuckle pilot portion 20 and the inner end surface in the axial direction and having a partially arcuate or linear cross-sectional shape). 23 is larger than the axial distance d to the outer diameter side opening 23 (L> d).

  Of the two seal lips 26, 27, the outer-diameter-side seal lip 27 that protrudes outward in the radial direction extends radially outward from the axially intermediate portion of the small-diameter portion 24. It has a shape to The leading edge (radially outer edge) of the seal lip 27 is in sliding contact with the inner peripheral surface of the axially intermediate portion of the knuckle pilot portion 20 over the entire circumference. In the case of this example, a step portion 29 is provided on the inner peripheral surface of the tip end portion of the small diameter portion 24 (the inner peripheral surface of the intermediate portion of the small diameter cylindrical portion 24a), and a vulcanization mold (not shown) is provided on the step portion 29 during vulcanization molding. The elastic material constituting the sealing material 25 is prevented from flowing inward in the axial direction along the inner peripheral surface of the small diameter portion 24.

According to the rolling bearing unit for supporting a wheel of the present example as described above, it exists on the inner diameter side of the outer ring 2 (the inner peripheral surface of the outer ring 2, the outer peripheral surface of the hub 3, the seal ring 14 and the cover 16a). Even when the pressure in the internal space 21a rises as the temperature in the internal space 21a increases, the cover 16a can be prevented from falling off from the axially inner end of the outer ring 2.
That is, in the case of this example, the vent hole 23 is provided in the axially intermediate portion of the cylindrical portion 17a constituting the cover 16a so as to penetrate the cylindrical portion 17a in the radial direction. Therefore, as shown in FIG. 3, when the pressure in the internal space 21a rises and the cover 16a is displaced in a direction (inward in the axial direction) coming out of the knuckle pilot portion 20, the cylindrical portion 17a is moved to the knuckle pilot. Before completely exiting from the portion 20, the internal space 21 a and the external space of the wheel-supporting rolling bearing unit 1 b are communicated by the vent hole 23. Even in this state, the outer half in the axial direction of the cylindrical portion 17a (the outer portion in the axial direction from the vent hole 23) is fitted with the inner peripheral surface of the knuckle pilot portion 20. The cover 16a does not fall off from the pilot portion 20. In the state where the internal space 21a and the external space communicate with each other through the vent hole 23, the air in the internal space 21a is discharged to the external space. For this reason, it is possible to prevent the pressure in the internal space 21a from further rising, and to prevent the cover 16a from being further displaced inward in the axial direction and falling off the knuckle pilot portion 20.

  Further, in the case of this example, the sealing material 25 having the sealing lip 26 on the inner diameter side is supported and fixed to the small diameter portion 24 provided at the inner end portion in the axial direction of the cylindrical portion 17a. For this reason, when the pressure in the rolling element installation space 15a provided with the rolling elements 4, 4 which is the axial outer space existing outside the sealing material 25 in the axial direction in the internal space 21a is increased. The area where the cover 16a receives this pressure can be reduced, and the force for displacing the cover 16a inward in the axial direction can be reduced. That is, when the amount of heat generated by the rotor constituting the disc brake increases and this heat is transmitted to the rotation side flange 8, a portion closer to the rotation side flange 8 side than the seal lip 26 (shaft) in the internal space 21a. The degree of the temperature rise of the rolling element installation space 15a existing in the outer portion in the direction (in the outer side in the direction) is particularly greater (than the axial inner space 35 existing in the axial direction). In the case of the first example of the conventional structure shown in FIG. 6 described above, when the heat of the disk rotor is transmitted to the rotation side flange 8, the pressure inside the internal space 21 rises, and this pressure is the bottom plate constituting the cover 16. It is added to the axially outer surface of the portion 18. On the other hand, in the case of this example, the sealing material 25 (inner peripheral surface side seal lip 26) divides the internal space 21a into the rolling element installation space 15a which is the axial outer space and the axial inner space 35. It is divided. For this reason, when the pressure in the rolling element installation space 15 a rises due to the temperature rise in the rolling element installation space 15 a due to the heat transmitted to the rotating flange 8, this pressure is outside the axial direction of the sealing material 25. It is added to the side surface (and the axially outer side surface of the tapered cylindrical portion 24b). Therefore, the force applied to the cover 16a based on the temperature rise in the rolling element installation space 15a to displace the cover 16a inward in the axial direction is kept small compared to the case of the first example of the conventional structure. I can do things.

In the inner space 21a, when the pressure difference between the rolling element installation space 15a existing on the axially outer side than the inner diameter side seal lip 26 and the axially inner space 35 is large, The leading edge of the inner diameter side seal lip 26 is elastically deformed inward in the axial direction, and the air in the rolling element installation space 15 a flows toward the axially inner space 35. The air flow rate has a correlation with a pressure difference between the rolling element installation space 15 a and the axial inner space 35. Accordingly, since the rate of pressure increase in the axial inner space 35 applied to the bottom plate portion 18a of the cover 16a can be moderated, the cover 16a can be hardly displaced inward in this direction also from this surface. .
The axial inner space 35 is partitioned from the rolling element installation space 15a by a seal ship 26 on the inner peripheral surface side. For this reason, since the pressure drop accompanying the increase in the volume of the axial inner space 35 when the cover 16a moves inward in the axial direction becomes large, it is difficult to remove the cover 16a also from this surface.

  In the case of this example, the front edge of the seal lip 26 and the outer peripheral surface of the shoulder portion 28 from the axial inner end edge of the outer peripheral surface of the shoulder portion 28 in a state where the cover 16a is fixed at a regular position. The axial distance L to the sliding contact portion is made larger than the axial distance d from the axial inner end edge of the knuckle pilot portion 20 to the opening portion of the vent hole 23 (L> d). For this reason, even when the cover 16a is displaced inward in the axial direction and the internal space 21a (the axially inner space 35) and the external space communicate with each other through the vent hole 23, the tip of the seal lip 26 The edge can be kept in sliding contact with the outer peripheral surface of the shoulder portion 28 of the inner ring 11 over the entire circumference. Accordingly, the grease sealed in the rolling element installation space 15a leaks outside from the axially inner opening of the outer ring 2, or mud water or the like enters the rolling element installation space 15a from the axially inner opening of the outer ring 2. It is possible to prevent foreign matter from entering more reliably.

Further, in the case of this example, since the vent hole 23 is provided in a portion located below the vehicle in the state where the wheel bearing rolling bearing unit 1b is assembled to the vehicle with respect to the circumferential direction, the cover 16a. Is displaced inward in the axial direction, and foreign matter such as muddy water entering the inside of the cover 16a is discharged to the external space in a state where the internal space 21a and the external space communicate with each other through the vent hole 23. I can do things.
Further, in the case of this example, the tip edge of the seal lip 26 on the inner diameter side of the seal member 25 provided in the small diameter portion 24 of the cover 16a is brought into sliding contact with the outer peripheral surface of the shoulder portion 28 over the entire circumference. The axially inner opening of the rolling element installation space 15a is closed. For this reason, even when a foreign matter such as muddy water enters the inside of the cover 16a, the tip edge of the seal lip 26 and the shoulder portion 28 tend to be an entry path of the foreign matter into the rolling element installation space 15a. It is possible to effectively prevent the foreign matter from reaching the sliding contact portion with the outer peripheral surface. Further, the end edge of the seal lip 27 on the outer diameter side of the seal material 25 is in sliding contact with the inner peripheral surface of the axial intermediate portion of the knuckle pilot portion 20 over the entire circumference. Thereby, it can prevent that the said foreign material penetrate | invades into the said rolling element installation space 15a from the clearance gap between the internal peripheral surface of the axial direction intermediate part of this knuckle pilot part 20, and the outer peripheral surface of the said cylindrical part 17a.

  Further, since the bottom plate portion 18a constituting the cover 16a has a circular flat plate shape, it has a truncated cone shape like the bottom plate portion 18 constituting the cover 16 of the first example of the conventional structure shown in FIG. Compared to the case, the volume of the internal space 21a (the axially inner space 35) can be kept small. Also from this aspect, it is possible to suppress an excessive increase in the pressure in the internal space 21a.

[Second Example of Embodiment]
FIG. 4 shows a second example of an embodiment of the present invention corresponding to claims 1 and 2. The cover 16b constituting the wheel support rolling bearing unit 1c of the present example is configured in a petri dish having a substantially U-shaped cross section by applying plastic processing such as drawing to a metal plate. That is, the cover 16b includes a circular plate-like bottom plate portion 18b and a cylindrical portion 17b that is bent at right angles from the outer peripheral edge of the bottom plate portion 18b to the outside in the axial direction and whose diameter (inner diameter and outer diameter) does not change in the axial direction. With. In the case of this example, the axially inner side surface of the bottom plate portion 18b in a state where the cover 16b is fitted and fixed to the knuckle pilot portion 20 provided at the inner end portion in the axial direction of the outer ring 2 (fixed at a normal position). And the axial inner end face of the outer ring 2 (knuckle pilot portion 20) are located on the same virtual plane (the bottom plate portion 18b exists on the inner diameter side of the axial inner end edge of the outer ring 2). The position of the cover 16b in the axial direction is restricted. Further, a seal ring 30 is mounted between the inner peripheral surface of the outer end portion in the axial direction of the cylindrical portion 17 b and the outer peripheral surface of the shoulder portion 28 of the inner ring 11. The seal ring 30 includes a cored bar 31 having an annular shape as a whole and a substantially L-shaped cross section, and an annular sealing material 25 a made of an elastic material reinforced by the cored bar 31. Then, in a state in which the metal core 31 is fitted into the inner peripheral surface of the axially outer end portion of the cylindrical portion 17b by an interference fit, the tip edge of the seal lip 26a constituting the seal material 25a is attached to the inner ring. 11 is in sliding contact with the outer peripheral surface of the shoulder portion 28 over the entire circumference. In the case of this example, a nose gasket 32 bulging (protruding) radially outward is formed in a portion of the sealing material 25a covering the inner end in the axial direction of the core 31. Foreign matter such as muddy water is prevented from entering the gap between the outer peripheral surface of the gold 31 and the inner peripheral surface of the cylindrical portion 17b. Specifically, foreign matter that has entered the cover 16b through the vent hole 23 formed in the cylindrical portion 17b moves to the rolling element installation space 15a through the fitting portion between the cored bar 31 and the cylindrical portion 17b. To prevent it.

According to the present example as described above, the rigidity in the radial direction at both axial ends of the cylindrical portion 17b is increased, and the fitting strength of the cover 16b to the inner peripheral surface of the knuckle pilot portion 20 is further stabilized. I can do things. That is, since the cored bar 31 of the seal ring 30 is fitted into the inner peripheral surface of the axially outer end portion of the cylindrical portion 17b with an interference fit, the radial direction of the axially outer end portion of the cylindrical portion 17b. High rigidity can be achieved. Further, the cylindrical portion 17b is formed in a state of being bent at a right angle from the outer peripheral edge portion of the circular flat plate-like bottom plate portion 18b to the axially outward direction, so that the radial direction of the inner end portion in the axial direction of the cylindrical portion 17b is formed. High rigidity can be achieved. Furthermore, since the axial dimension of the cylindrical portion 17b can be increased, the fitting force of the fitting portion between the cylindrical portion 17b and the knuckle pilot portion 20 can be increased.
Other configurations and operational effects are the same as those of the first example of the embodiment described above.

[Third example of embodiment]
FIG. 5 shows a third example of an embodiment of the present invention corresponding to claims 1 to 3. The wheel support rolling bearing unit 1d of this example is an internal fit by tightly fitting the cylindrical portion 17c constituting the petri dish-like cover 16c to the inner peripheral surface of the knuckle pilot portion 20 provided at the axially inner end portion of the outer ring 2. doing. In the case of this example, a seal ring 30a comprising a metal core 31a made of a metal and having an annular shape as a whole and a substantially L-shaped cross section, and an elastic sealing material 25b reinforced by the metal core 31a. Is fitted and fixed to the inner peripheral surface of the outer knuckle pilot portion 20 in the axially outer portion with an annular gap 33 interposed between the cylindrical portion 17c and the inner end surface in the axial direction. That is, the metal core 31a includes the inner end surface in the axial direction of the seal ring 30a (including the portion of the sealing material 25b that covers the inner end surface in the axial direction of the metal core 31a) and the axial direction of the cylindrical portion 17c. In the state where the annular gap 33 is interposed over the entire circumference between the outer end face and the outer end face, the inner end face of the knuckle pilot portion 20 is fitted with an interference fit on the inner peripheral face. At the same time, the tip edge of the seal lip 26b constituting the seal material 25b is slidably contacted with the outer peripheral surface of the shoulder portion 28 of the inner ring 11 over the entire circumference. In addition, a nose gasket 32a bulging (protruding) radially outward is formed in a portion of the sealing material 25b that covers the inner end surface in the axial direction of the metal core 31a, and the inner circumference of the knuckle pilot portion 20 is formed. Foreign matter such as muddy water is prevented from entering the gap between the surface and the outer peripheral surface of the cored bar 31a.

Further, in the case of this example, a portion of the outer peripheral surface of the cylindrical portion 17c that is positioned below the vehicle in a state where the wheel support rolling bearing unit 1d is assembled to the vehicle with respect to the circumferential direction, A groove 34 is provided in a range from the outer end portion in the direction to the middle portion so as to open to the outer end edge in the axial direction of the cylindrical portion 17c, and the concave groove 34 is provided on the outer end surface in the axial direction of the cylindrical portion 17c. The notch 36 is provided in a state where the radially inner end (bottom) of the cylinder is in communication with the inner peripheral surface of the cylindrical portion 17c. Then, with the cover 16c and the seal ring 30a fixed at regular positions, from the axial outer end edge of the outer peripheral surface of the shoulder portion 28, the tip edge of the seal lip 26b and the outer peripheral surface of the shoulder portion 28 The axial distance L to the sliding contact portion with the axial distance d ₁ between the axial inner end surface of the seal ring 30a and the axial outer end surface of the cylindrical portion 17c, and the axial inner end of the outer ring 2 This is larger than the sum of the axial distance d ₂ from the axial inner end edge of the fitting portion of the cylindrical portion 17 to the axial inner end portion of the concave groove 34 (L> d ₁ + d ₂ ).

In the case of this example as described above, when heat is transmitted to the rotation side flange 8 (see FIG. 1), first, in the inner space 21a, the inside of the rolling element installation space 15a that exists on the inner side in the axial direction of the seal ring 30a. Temperature rises. As a result, the pressure in the rolling element installation space 15a rises, the seal ring 30a is displaced inward in the axial direction, and the axial inner end surface of the seal ring 30a and the shaft of the cover 16c (cylindrical portion 17c). The outer end surface of the direction comes into contact. When the pressure in the internal space 21a further increases from this state, the seal ring 30a and the cover 16c are integrated and displaced inward in the axial direction. And the state where the axial direction inner end part of the said ditch | groove 34 exists in the axial direction inner side rather than the axial direction inner end surface of the said outer ring | wheel 2 (The state where the axial direction inner end part of this ditch | groove 34 opened to external space) Then, the internal space 21 a and the external space are communicated with each other through the concave groove 34 and the notch 36. As a result, the air in the internal space 21a (the axially inner space 35) is discharged to the external space. In the case of this example, the size of each part is regulated so as to satisfy the relationship (L> d ₁ + d ₂ ). For this reason, even when the internal space 21a and the external space communicate with each other via the concave groove 34 and the notch 36, the end edge of the seal lip 26b extends to the outer peripheral surface of the shoulder 28. It can be touched by sliding.

If the cover 16c is displaced inward in the axial direction, the annular gap 33 and the external space can communicate with each other, and the air in the axial inner space 35 can be discharged to the external space. Instead of the concave grooves 34, the outer peripheral surface of the cylindrical portion 17c can be roughened, or knurled eyes can be provided.
Other configurations and operational effects are the same as those of the first example of the above-described embodiment and the second example of the above-described embodiment.

  In the present invention, as in the first example of the conventional structure shown in FIG. 6 and the examples of the embodiment shown in FIGS. When the rolling bearing unit for supporting a wheel is used, the volume of the inner space in the axial direction can be reduced, so that the effect of preventing the cover from falling off can be obtained more effectively. However, the present invention can also be implemented by a wheel bearing rolling bearing unit in which the hub body and the inner ring are coupled and fixed by nuts as in the second example of the conventional structure shown in FIG.

DESCRIPTION OF SYMBOLS 1, 1a-1d Rolling bearing unit for wheel support 2 Outer ring 3 Hub 4 Rolling body 5 Static side flange 6a, 6b Outer ring raceway 7a, 7b Inner ring raceway 8 Rotating side flange 9 Cage 10 Hub body 11 Inner ring 12 Small diameter step part 13 Caulking Part 14 Seal ring 15, 15a Rolling element installation space 16, 16a-16c Cover 17, 17a-17c Cylindrical part 18, 18a, 18b Bottom plate part 19, 19a Hook part 20 Knuckle pilot part 21, 21a Inner space 22 Nut 23, 23a Ventilation hole 24 Small diameter portion 24a Small diameter cylindrical portion 24b Tapered tube portion 25, 25a, 25b Seal material 26, 26a, 26b Seal lip 27 Seal lip 28 Shoulder portion 29 Step portion 30, 30a Seal ring 31, 31a Core metal 32, 32a Nose Gasket 33 Annular gap 34 Concave groove 35 Shaft Directional inner space 36 Notch

Claims (3)

An outer ring having a double-row outer ring raceway on the inner peripheral surface and not rotating during use;
A hub that has a double-row inner ring raceway on its outer peripheral surface and that rotates with the wheel during use;
A plurality of rolling elements provided between the outer ring raceways and the inner ring raceways so as to be capable of rolling;
In a wheel-supporting rolling bearing unit, comprising: a cylindrical portion fitted on an inner peripheral surface of an inner end portion in the axial direction of the outer ring; and a cover having a bottom plate portion that hermetically closes an axially inner opening of the cylindrical portion. And
Sealing means for closing the axially inner opening of the rolling element installation space existing between the inner peripheral surface of the outer ring and the outer peripheral surface of the hub is provided, and the axially inner end or intermediate portion of the cylindrical portion When the cover is fixed at the regular position, the outer diameter side opening is blocked by the outer ring, and when the cover is displaced inward in the axial direction from the regular position, the inner space and the outer space of the cover A rolling bearing unit for supporting a wheel, characterized in that an air passage is provided to communicate with each other. The sealing means has a tip edge of a seal lip supporting a base end portion with respect to an outer end portion in the axial direction of the cylindrical portion, a portion adjacent to the inner side in the axial direction of the inner ring raceway on the inner side in the axial direction. It is constructed by sliding and making contact with the outer peripheral surface of the shoulder portion provided on the entire circumference,
The axial distance from the axial inner end edge of the outer peripheral surface of the shoulder portion to the sliding contact portion between the tip edge of the seal lip and the outer peripheral surface of the shoulder portion is the axial inner end portion of the outer ring and the cylinder. The rolling bearing unit for supporting a wheel according to claim 1, wherein the wheel bearing rolling bearing unit is larger than an axial distance from an axial inner end edge of the fitting portion to the opening to an opening on the outer diameter side of the air passage. The sealing means is an annular cored bar that is fitted and fixed to the outer circumferential part of the outer ring with an interference fit on the outer side in the axial direction than the part in which the cylindrical part is fitted. A seal ring comprising a seal material having a seal lip supporting a base end portion;
A recess provided in the state where the air passage opens from the outer end surface in the axial direction of the outer peripheral surface of the cylindrical portion to the intermediate portion in an open state at the outer edge in the axial direction of the cylindrical portion, and the shaft of the cylindrical portion It comprises a cutout portion provided in a state in which the axially outer end portion of the concave portion and the inner peripheral surface of the cylindrical portion communicate with each other on the direction outer end surface,
The axial distance from the axial inner end edge of the outer peripheral surface of the shoulder portion to the sliding contact portion between the tip edge of the seal lip and the outer peripheral surface of the shoulder portion is the axial inner end surface of the seal ring and the cylinder. The axial distance between the axial outer end surface of the portion and the axis from the axial inner end edge of the fitting portion between the axial inner end portion of the outer ring and the cylindrical portion to the axial inner end portion of the recess The rolling bearing unit for supporting a wheel according to claim 2, wherein the rolling bearing unit is larger than a sum of the directional distances.

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