JP2023078824A - hub unit bearing - Google Patents

Abstract

To provide a hub unit bearing capable of reducing an edge load even when relative inclination between a ball bearing part and a roller bearing part is large, while preventing deterioration in service life of the roller bearing part with high rigidity, in a constitution where rolling bodies in each row are balls and conical rollers.SOLUTION: A hub unit bearing 10 comprises a plurality of balls 14 rollably arranged between one outer ring raceway 21a and one inner ring raceway 35a, and a plurality of conical rollers 15 rollably arranged between the other outer ring raceway 21b and the other inner ring raceway 35b. At least some of the plurality of conical rollers 15 are conical rollers having a hollow part 15a along a central axis L of the roller.SELECTED DRAWING: Figure 1

Description

The present invention relates to a hub unit bearing, and more particularly to a hub unit bearing in which tapered rollers and balls are used for each row as rolling elements in double rows.

As a hub unit bearing 100 for rotatably supporting the wheels of an automobile with respect to a suspension system, as shown in FIG. In order to increase the diameter and compensate for the life of the inboard side row having a small pitch circle diameter, it is known that the rolling elements on the outboard side are balls 101 and the rolling elements on the inboard side are tapered rollers 102. (See, for example, Patent Document 1).

On the other hand, in the hub unit bearing described in Patent Document 2, in order to increase moment rigidity while achieving compactness, it is also known that the rolling elements on the outboard side are tapered rollers and the rolling elements on the inboard side are balls. .

JP 2007-290530 A JP 2008-169860 A

In a hub unit bearing (hereinafter referred to as a "hybrid-type hub unit bearing") having a ball bearing portion and a roller bearing portion with such balls and tapered rollers as rolling elements in each row, the roller bearing portion and the ball bearing portion Since the appropriate preload range is different for both bearings, the preload range in which both bearings can demonstrate their performance is narrow.

In addition, since there is a large difference in rigidity between the roller and ball bearings, changes in the amount of deformation of the raceway surface and rolling elements due to dimensional errors that affect preload are greater on the ball bearing side, which has relatively lower rigidity, and preload is reduced. If the preload is too small, there is a possibility that adverse effects such as lack of rigidity and excessive preload will shorten the service life.

On the other hand, compared to hub unit bearings with tapered rollers on both rows of rolling elements (hereafter referred to as "double-row conical type hub unit bearings"), hybrid-type hub unit bearings have a higher rigidity. The load sharing on the side of the roller bearing portion with a high temperature is increased, and the service life of the roller bearing portion is shortened.

Also, in the hybrid type hub unit bearing, the relative inclination between the raceway surface and the rolling surface of the roller bearing portion is greater than in the double row conical type hub unit bearing, and edge load is likely to occur. If the crowning amount of the raceway surface and tapered rollers is made larger than normal (for example, the allowable inclination angle of 3 minutes) to prevent the generation of edge loads, the load bearing surface is reduced, leading to a reduction in the life of the roller bearing.

The present invention has been made in view of the above-mentioned problems, and its object is to prevent a reduction in the service life of a highly rigid roller bearing portion and to To provide a hub unit bearing capable of alleviating an edge load even if the relative inclination of a bearing part and a roller bearing part becomes large.

The above objects of the present invention are achieved by the following configurations.
(1) an outer ring having a double-row outer ring raceway on its inner peripheral surface;
A hub axle having a wheel mounting flange on the outboard side and a small diameter step portion formed on the inboard side; a hub having a double-row inner ring raceway facing the double-row outer ring raceway;
a plurality of balls rollably disposed between one of the double-row outer ring raceways and one of the double-row inner ring raceways;
a plurality of tapered rollers rollably arranged between the other of the double-row outer ring raceways and the other of the double-row inner ring raceways;
A hub unit bearing comprising:
A hub unit bearing, wherein at least some of the plurality of tapered rollers are tapered rollers having a hollow portion along the central axis of the roller.
(2) The hub unit bearing according to (1), wherein the hollow portion penetrates along the central axis of the roller.
(3) the tapered roller has a head portion on the large diameter side and a tail portion on the small diameter side,
The hub unit bearing according to (1), wherein the hollow portion is open only on the tail portion side of the tapered roller.
(4) The hub unit bearing according to any one of (1) to (3), wherein the plurality of tapered rollers include tapered rollers having the hollow portion and solid tapered rollers.

According to the hub unit bearing of the present invention, in the configuration in which the rolling elements in each row are balls and tapered rollers, at least a portion of the plurality of tapered rollers has a hollow portion along the central axis of the roller, thereby increasing rigidity. It is possible to alleviate the edge load even if the relative inclination between the ball bearing and the roller bearing becomes large while preventing the life of the high roller bearing from being shortened.

1 is a cross-sectional view of a hub unit bearing according to a first embodiment of the invention; FIG. FIG. 5 is a cross-sectional view of a hub unit bearing according to a first modified example of the first embodiment; FIG. 8 is a cross-sectional view of a hub unit bearing according to a second modification of the first embodiment; FIG. 11 is a cross-sectional view of a hub unit bearing according to a third modified example of the first embodiment; FIG. 5 is a cross-sectional view of a hub unit bearing according to a second embodiment of the invention; FIG. 10 is a cross-sectional view of a conventional hub unit bearing;

Hereinafter, hub unit bearings according to respective embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIG. 1, a driven wheel hub unit bearing 10 of the present embodiment supports a wheel, which is a driven wheel, rotatably with respect to a suspension device such as a knuckle. A hub 30, which is a rotating wheel, is rotatably supported on the inner diameter side via a plurality of balls 14 and a plurality of tapered rollers 15 arranged in rows. That is, the hub unit bearing of this embodiment constitutes a hybrid type hub unit bearing including a ball bearing portion and a roller bearing portion.

The outer ring 20 has a mounting flange 22 coupled and fixed to a knuckle (not shown) constituting a suspension system on its outer peripheral surface, and has double-row outer ring raceways 21a and 21b on its inner peripheral surface. The mounting flange 22 is provided with a female threaded hole 23 for coupling the outer ring 20 to the knuckle.

The hub 30 has an inner ring 32 fitted onto a small-diameter stepped portion 34 of a hub ring 31 and joined and fixed by a caulking portion 33. A double-row inner ring raceway 35a faces the outer ring raceways 21a and 21b on the outer peripheral surface. , 35b. On the outboard side of the hub wheel 31, a wheel mounting flange 36 for mounting a wheel and a brake rotor constituting the wheel is provided in a portion that protrudes further to the outboard side than the outboard side end opening of the outer ring 20. ing. The wheel and brake rotor are fastened together by a hub bolt 37 and a hub nut (not shown) and fixedly connected to the wheel mounting flange 36 .

Between the outer ring raceway 21a on one side and the inner ring raceway 35a on the one side on the outboard side, a plurality of balls 14 are provided by a retainer 16 so as to be free to roll at equal intervals in the circumferential direction. there is Between the other outer ring raceway 21b and the other inner ring raceway 35b on the inboard side, a plurality of tapered rollers 15 are provided by a retainer 17 so as to be free to roll at equal intervals in the circumferential direction. ing. That is, the outer ring raceway 21a of the outer ring 20 and the inner ring raceway 35a of the hub ring 31 form a spherical raceway groove in which the balls 14 roll, and the outer ring raceway 21b of the outer ring 20 and the inner ring raceway 35b of the inner ring 32 form tapered rollers. 15 constitutes a tapered raceway surface on which it rolls.
Therefore, the hub unit bearing 10 of this embodiment has a ball bearing portion on the outboard side and a roller bearing portion on the inboard side to compensate for the life of the roller bearing portion on the inboard side.

The term "outboard side" as used herein refers to the axial direction of the hub unit bearing, and the term "inboard side" refers to the lateral direction of the vehicle body when the hub unit bearing 10 is assembled to the vehicle. This is the inner side.
Further, in the present embodiment, the hub axle forming the inner ring raceway 35a on the outboard side is referred to as the hub wheel 31. As shown in FIG.

Further, the outboard side end opening and the inboard side end opening of the bearing space 12 where the plurality of balls 14 and the plurality of tapered rollers 15 are installed between the inner peripheral surface of the outer ring 20 and the outer peripheral surface of the hub 30 The openings are closed by seal rings 13 respectively.

Here, in the present embodiment, the plurality of tapered rollers 15 on the inboard side have hollow portions 15a penetrating along the central axis L of the roller. As a result, the rigidity of the tapered roller 15 can be lowered, and the load sharing on the roller bearing portion side can be reduced, thereby preventing the life of the roller bearing portion from being shortened.

Further, even if the relative inclination between the outer ring raceway 21b and the inner ring raceway 35b of the roller bearing portion and the rolling surface of the tapered roller 15 increases, the tapered roller 15 is deformed (the side with the higher surface pressure in the axial direction collapses in the radial direction). By doing so, it is possible to alleviate the edge load without applying heavy crowning (increasing the amount of crowning on the raceway surface and transfer surface than usual).
In addition, it is preferable that the hollow portion 15 a does not straddle the small-diameter side annular portion of the retainer 17 .

FIG. 2 is a cross-sectional view of a hub unit bearing according to a first modified example of the first embodiment. The hub unit bearing 10A of this modification differs from that of the above embodiment in that the inner ring raceway 35a on which the balls 14 roll is constituted by the inner ring 40 separate from the hub axle 31. As shown in FIG. That is, the hub 30 of this modification includes a hub axle 31 and a pair of inner rings 32 and 40 that are press-fitted into a small-diameter step portion 34 of the hub axle 31 and fixed.
Also in this case, the same effect as the above embodiment can be obtained.

FIG. 3 is a cross-sectional view of a hub unit bearing according to a second modification of the first embodiment. In the hub unit bearing 10B of this modified example, the plurality of tapered rollers 15 have hollow portions 15b along the roller central axis L that are open only on the tail portion side of the small diameter side of the tapered rollers 15, unlike the embodiment described above. Different from things. That is, the tapered roller 15 of this modification has a solid head portion on the large diameter side, and a hollow tail portion where the relative inclination of the raceway surface and roller rolling surface increases and edge load tends to occur. , By reducing the rigidity of the side where edge load is likely to occur and making it easier to deform, the occurrence of edge load is suppressed. In the tapered roller 15, a hollow portion 15b is formed extending from the tail side to the longitudinal intermediate portion of the tapered roller 15. As shown in FIG.
Also in this case, the same effect as the above embodiment can be obtained.

FIG. 4 is a cross-sectional view of a hub unit bearing according to a third modified example of the first embodiment; In the hub unit bearing 10C of this modified example, in the plurality of tapered rollers 15, as in the second modified example, the hollow portions 15b along the roller central axis L are open only on the tail side of the tapered rollers 15. The inner ring raceway 35a on which the hub 14 rolls is composed of the inner ring 40 separate from the hub axle 31, as in the first modification.
Also in this case, the same effect as the above embodiment can be obtained.

(Second embodiment)
Next, a hub unit bearing according to a second embodiment of the invention will be described with reference to FIG.

In the driven wheel hub unit bearing 10D of the second embodiment, a hybrid type hub unit bearing that compensates for moment rigidity is configured by using a roller bearing portion on the outboard side and a ball bearing portion on the inboard side.
That is, the outer ring raceway 21a of the outer ring 20 and the inner ring raceway 35a of the hub ring 31, which are on the outboard side, form a tapered raceway surface on which the tapered rollers 15 roll, and the outer ring of the outer ring 20, which is on the inboard side. The raceway 21b and the inner ring raceway 35b of the inner ring 32 form a spherical raceway groove in which the balls 14 roll.

In this hub unit bearing 10D as well, the tapered rollers 15 used in the roller bearing portion on the outboard side have a hollow structure to reduce the rigidity on the outboard side, thereby reducing the load sharing on the bearing portion side. This prevents the life of the bearing from being shortened.

In addition, even if the relative inclination between the raceway surface and the rolling surface of the roller bearing increases, the tapered roller 15 is deformed (the side with the higher axial surface pressure is crushed). allows for mitigation.
Other configurations and actions are the same as those of the first embodiment.

It should be noted that the present invention is not limited to the above-described embodiments, and can be modified, improved, etc. as appropriate.
For example, the hub unit bearings of the above-described embodiments are for driven wheels, but the present invention can also be applied to drive wheels.

Further, in each of the above-described embodiments, all the tapered rollers 15 having the hollow portions 15a are used as the roller bearing portions, but any tapered rollers 15 having at least a portion of the hollow portions 15a may be used. That is, for the roller bearing portion, tapered rollers having the hollow portion 15a and normal solid tapered rollers may be used by mixing them in an appropriate ratio and distribution. In this case, it is preferable that the tapered rollers having the hollow portions 15a be arranged at equal intervals in the circumferential direction.

10 hub unit bearing 14 ball 15 tapered rollers 15a, 15b hollow portion 20 outer ring 21a, 21b outer ring raceway 30 hub 31 hub ring (hub shaft)
32, 40 inner ring 34 small diameter stepped portions 35a, 35b inner ring raceway 36 wheel mounting flange

Claims (4)

an outer ring having a double-row outer ring raceway on its inner peripheral surface;
A hub axle having a wheel mounting flange on the outboard side and a small diameter step portion formed on the inboard side; a hub having a double-row inner ring raceway facing the double-row outer ring raceway;
a plurality of balls rollably disposed between one of the double-row outer ring raceways and one of the double-row inner ring raceways;
a plurality of tapered rollers rollably arranged between the other of the double-row outer ring raceways and the other of the double-row inner ring raceways;
A hub unit bearing comprising:
At least some of the plurality of tapered rollers are tapered rollers having a hollow portion along the central axis of the roller,
hub unit bearings. 2. The hub unit bearing according to claim 1, wherein said hollow portion penetrates along said roller central axis. The tapered roller has a head portion on the large diameter side and a tail portion on the small diameter side,
2. The hub unit bearing according to claim 1, wherein said hollow portion opens only on said tail portion side of said tapered roller. The hub unit bearing according to any one of claims 1 to 3, wherein the plurality of tapered rollers include tapered rollers having the hollow portion and solid tapered rollers.

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