Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2001-12-21
2004-08-10
Siconolfi, Robert A. (Department: 3683)
Bearings
Rotary bearing
Antifriction bearing
C384S589000, C301S108100
Reexamination Certificate
active
06773165
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a wheel bearing device for supporting a wheel of an automobile and a method of manufacturing the same.
2. Description of the Related Art
Wheel bearing devices are broadly divided into two categories: those for driving wheels, and those for driven wheels. For example, in a wheel bearing device for driving wheels, as
FIG. 33
shows, a hub ring
100
, a bearing
200
, and a constant velocity universal joint
400
are unitized together. Further, of inner raceways of the bearing
200
in double rows, one of the inner raceways, or an inner raceway
270
, is formed at the hub ring
100
, and the other inner raceway, or an inner raceway
280
, is formed at an outer joint member
410
of the constant velocity universal joint
400
.
The hub ring
100
has a flange
140
for supporting a wheel, and the inner raceway
270
is formed at an outside periphery, near the flange
140
, of the hub ring
100
. The outer joint member
410
of the constant velocity universal joint
400
comprises a mouth portion
460
of a bowl shape and a solid stem portion
450
, and is fitted on the hub ring
100
at the stem portion
450
through serration. A shoulder portion
470
of the outer joint member
400
is in contact with an end face of the hub ring
100
. The inner raceway
280
is formed at a portion of the outer joint member
410
, or at an outside periphery of the mouth portion
460
near the stem portion
450
. Outer raceways
240
in double rows facing to the inner raceways
270
and
280
are formed at an inside periphery of an outer member
210
of the bearing
200
. Further, rolling members
220
in double rows are assembled between the inner raceways
270
and
280
in double rows and the outer raceways
240
in double rows.
As indicated by numeral
450
′, an end of the stem portion
450
projecting from the hub ring
100
in an axial direction is bent for swaging to join together the stem portion
450
and the hub ring
100
. Further, the outer member
210
is fixed to a suspension device by a fixing portion
230
formed in a flange shape facing outward at an outside periphery of the outer member
210
, and a wheel is fixed to the flange
140
of the hub ring
100
.
Another example of a wheel bearing device is, as
FIG. 34
shows, such that an inner ring
350
is fitted onto a small-diameter cylindrical portion
170
formed at the outside periphery of the hub ring
100
. Known as this type of wheel bearing device is such that an end of the small-diameter cylindrical portion
170
of the hub ring
100
projecting from the inner ring
350
in the axial direction is, as denoted by numeral
170
′, bent for swaging to join together the inner ring
350
and the hub ring
100
.
With the wheel bearing device described above, the bearing is generally given with preload, and precise preload control is made when assembling the bearing. In an automobile, however, large moment load is applied to the bearing portion particularly when it turns. Therefore, in a method where an end of the stem portion
450
of the outer joint member
410
(as shown in
FIG. 33
) or an end of the small-diameter cylindrical portion
170
(as shown in
FIG. 34
) is bent and swaged, the swaged portion may loosen owing to a reason such as spring-back at the swaged portion, resulting in a possible change in dimension between the inner raceways in double rows and causing loss of preload.
SUMMARY OF THE INVENTION
Therefore, an object of the invention is to prevent loosening at a swaged portion.
Another object of the invention is to provide a method of manufacturing a wheel bearing device that can put preload to the inside of the bearing when swaging for joining, and can easily provide an appropriate amount of preload.
In order to achieve the objects described above, in a wheel bearing device according to the invention, a hub ring, a constant velocity universal joint, and a bearing are unitized together, the hub ring and an outer joint member of the constant velocity universal joint are fitted together, of inner raceways in double rows of the bearing, one of the inner raceways is formed at the hub ring while at the same time the other inner raceway is formed at the outer joint member. Further, a hardened irregular portion is formed at an outside-diameter side member at a fit portion of the hub ring and the outer joint member, and also at the same time, a low hardness portion having a hardness lower than that of the irregular portion is provided at an inside-diameter side member. Then, the low hardness portion is expanded in diameter to make it bite into the irregular portion, so that the hub ring and the outer joint member are unitized together.
When the diameter of the low hardness portion is expanded to make it bite into the irregular portion as described above, joining strength is improved in comparison with conventional swaging made by bending. Consequently, the hub ring and the outer joint member that are fitted together are prevented from loosening, and loss of preload can be avoided.
An effect similar to that described above is obtainable when a hardened irregular portion is provided at the inside-diameter side member. In this case, the irregular portion itself is expanded in diameter to make it bite into a mating face to which the irregular portion is fitted. However, if the irregular portion is excessively hardened, there is fear that swaging cracks occur in a base material of the irregular portion as the diameter is expanded. Therefore, the irregular portion cannot be made too hard; Rockwell hardness (C scale, hereafter as well) of from about HRc 40 to 45 is the limit of the hardness. With such hardness as above, however, the difference in hardness from its mating face of fitting is only about HRc 20 to 25, and therefore the irregular portion may be crushed as it bites into the mating face, causing possible lack in joining strength. As a countermeasure thereto, diameter-expansion allowance (extent of expansion toward an outside-diameter sides of the irregular portion may be increased. In this case, however, when once the irregular portion has bitten into its mating face to a certain depth, the fit portion starts to expands only toward an outside-diameter side afterward without biting into the mating face, thereby producing poor joining force.
On the other hand, when an member (an outside-diameter side member) having the irregular portion as described above and an member (an inside-diameter side member) to be expanded in diameter are arranged as separate members, it is possible to sufficiently harden (to about HRc 60, for example) the irregular portion. With the method described above, the irregular portion is prevented from being crushed in a swaging process and the member to be expanded in diameter can be provided with a low hardness portion having excellent ductility at the same time. Swaging cracks can be prevented from occurring through the expansion of this low hardness portion. Therefore, swaging is made into a deep depth between the hub ring and the outer joint member, so that sufficient joining strength can be secured.
As an embodiment for fitting together the hub ring and the outer joint member, there can be a case where the outside-diameter side member at the fit portion is the hub ring and the inside-diameter side member is the outer joint member (
FIG. 1
) or a case where the, outside-diameter side member at the fit portion is the outer joint member and the inside-diameter side member is the hub ring (FIG.
7
).
Further, a wheel bearing device according to the invention comprises a hub ring and a bearing that are unitized together, the hub ring and an inner ring of the bearing are fitted together, and, of inner raceways in double rows of the bearing, one of the inner raceways is formed at the hub ring while at the same time the other inner raceway is formed at the inner ring. In this wheel bearing device, moreover, a hardened irregular portion is formed at an outside-diameter side member at a fit portion of the hub ring
Hozumi Kazuhiko
Ozawa Masahiro
Sahashi Koji
Sone Keisuke
Umekida Mitsuru
Arent Fox Kintner & Plotkin & Kahn, PLLC
NTN Corporation
Siconolfi Robert A.
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