U.S. patent application number 10/580961 was filed with the patent office on 2007-12-13 for bearing apparauts for a wheel of vehicle.
Invention is credited to Akira Fujimura, Hiroshi Kawamura, Koji Nishino, Hisashi Ohtsuki, Kazuhisa Shigeoka.
Application Number | 20070286536 10/580961 |
Document ID | / |
Family ID | 34657731 |
Filed Date | 2007-12-13 |
United States Patent
Application |
20070286536 |
Kind Code |
A1 |
Kawamura; Hiroshi ; et
al. |
December 13, 2007 |
Bearing Apparauts for a Wheel of Vehicle
Abstract
A vehicle wheel bearing apparatus which reduces the weight, size
and number of parts and also prevents ingress of rain water or
dusts and leakage of differential gear oil has an axle housing
supported under a body of a vehicle. A hollow drive shaft is
inserted into the axle housing. A wheel bearing is arranged between
the drive shaft and an opening of the axle housing and is
structured as a unit including a wheel hub and a double row rolling
bearing. The wheel bearing includes an inner member with a wheel
hub integrally formed with a wheel mounting flange on one end and
an axially extending cylindrical portion. At least one inner ring
is press-fit onto the cylindrical portion of the wheel hub. The
inner ring is formed with at least one of the inner raceway
surfaces on its outer circumferential surface. An outer member is
arranged around the inner member and formed with double row outer
raceway surfaces on its inner circumferential surface opposite to
the inner raceway surfaces. Double row rolling elements are
arranged between the inner and outer raceway surfaces of the inner
member and the outer member. A cage freely rollably holds the
rolling elements. Seals seal an annular space between the inner
member and the outer member. A cap, having a metal core formed from
steel, is press-fit into an end of a central bore of the wheel
hub.
Inventors: |
Kawamura; Hiroshi;
(Shizuoka-ken, JP) ; Shigeoka; Kazuhisa;
(Shizuoka-ken, JP) ; Fujimura; Akira;
(Shizuoka-ken, JP) ; Nishino; Koji; (Shizuoka-ken,
JP) ; Ohtsuki; Hisashi; (Shizuoka-ken, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
34657731 |
Appl. No.: |
10/580961 |
Filed: |
October 14, 2004 |
PCT Filed: |
October 14, 2004 |
PCT NO: |
PCT/JP04/15144 |
371 Date: |
August 30, 2006 |
Current U.S.
Class: |
384/58 ;
301/108.1 |
Current CPC
Class: |
F16J 15/121 20130101;
F16C 35/063 20130101; F16J 15/04 20130101; Y02T 10/86 20130101;
B60B 35/121 20130101; F16C 19/386 20130101; F16C 43/04 20130101;
F16C 2326/02 20130101; B60B 27/00 20130101 |
Class at
Publication: |
384/058 ;
301/108.1 |
International
Class: |
F16C 19/28 20060101
F16C019/28; B60B 27/00 20060101 B60B027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 2003 |
JP |
2003-401112 |
Mar 19, 2004 |
JP |
2004-079683 |
Sep 16, 2004 |
JP |
2004-269093 |
Claims
1.-12. (canceled)
13. A vehicle wheel bearing apparatus for a wheel of vehicle
comprising: an axle housing supported under a body of a vehicle; a
hollow drive shaft inserted into the axle housing; a wheel bearing
arranged between the drive shaft and an opening of the axle housing
and structured as a unit of a wheel hub and a double row rolling
bearing; the wheel bearing comprising: an inner member including a
wheel hub integrally formed with a wheel mounting flange on one end
and an axially extending cylindrical portion; at least one inner
ring press-fit onto the cylindrical portion of the wheel hub and
said at least one inner ring with at least one inner raceway
surface formed on its outer circumferential surface; an outer
member arranged around the inner member and formed with double row
outer raceway surfaces on its inner circumferential surface
opposite to the inner raceway surfaces; double row rolling elements
arranged between the inner and outer raceway surfaces of the inner
member and the outer member; a cage for freely rollably holding the
rolling elements; seals for sealing an annular space between the
inner member and the outer member; and a cap having a metal core is
press-fit into an end of a central bore of the wheel hub.
14. The vehicle wheel bearing apparatus of claim 13 wherein said at
least one of said inner raceway surfaces is formed directly on the
outer circumferential surface of the wheel hub.
15. The vehicle wheel bearing apparatus of claim 13 wherein the end
of said cylindrical portion is plastically deformed radially
outward to form a caulked portion to prevent the inner ring from
slipping off of the cylindrical portion of the wheel hub.
16. The vehicle wheel bearing apparatus of claim 15 wherein the
outer circumferential region of the wheel mounting flange from its
base of an inboard side to the cylindrical portion is hardened by
high frequency induction hardening to have a surface hardness of
54.about.64 HRC, and the caulked portion remains unhardened to have
a surface hardness of 25 HRC or less after forging.
17. The vehicle wheel bearing apparatus of claim 13 wherein said
cap is press-fit into a central bore of the wheel mounting flange
of wheel hub.
18. The vehicle wheel bearing apparatus of claim 13 wherein said
cap comprises a metal core of steel having a substantially "C"
shaped configuration cross section and an elastic member attached
to at least part of its fitting portion.
19. The vehicle wheel bearing apparatus of claim 18 wherein said
cap is press-fit so that the circumferential edge of its fitting
portion is oriented toward the outboard side.
20. The vehicle wheel bearing apparatus of claim 18 wherein said
circumferential edge of the fitting portion of the metal core is
formed with a radially outwardly extending bead, and an annular
groove is formed on the central bore of the wheel hub to engage the
bead.
21. The vehicle wheel bearing apparatus of claim 18 wherein said
cap is limited against axial movement by steps provided at either
sides of the cap.
22. The vehicle wheel bearing apparatus of claim 13 wherein said
cap comprises a metal core having a substantially "C"-shaped
configuration cross section, an annular recess is formed on the
inner circumferential surface of the wheel hub, and the fitting
portion of the cap is formed with a projection adapted to be
engaged with the annular recess.
23. The vehicle wheel bearing apparatus of claim 22 wherein said
projection is formed by plastic deformation after the cap has been
press-fit into the bore of the wheel hub.
24. The vehicle wheel bearing apparatus of claim 13 wherein said
cap is press-fit with an interference of 0.05.about.0.3 mm.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a National Stage of International
Application No. PCT/JP2004/015144, filed Oct. 14, 2004, which
claims priority to Japanese Patent Application No. 2003-401112,
filed Dec. 1, 2003, Japanese Patent Application No. 2004-0079683,
filed Mar. 19, 2004 and Japanese Patent Application No.
2004-269093, filed Sep. 16, 2004. The disclosures of the above
applications are incorporated herein by reference.
FIELD
[0002] The present disclosure relates to a vehicle wheel bearing
apparatus to rotatably support the wheel relative to a suspension
apparatus of the vehicle and, more particularly, to a vehicle wheel
bearing apparatus of the semi-floating type where a driving wheel
is supported by a double row rolling bearing.
BACKGROUND
[0003] In a vehicle such as a truck having a body with a frame
structure, an axle structure of a driving wheel of a full-floating
type bearing has been widely adopted. In recent driving wheel
supporting structure, a unit structure of a double row rolling
bearing has been widely adopted. This unit improves the readiness
of assembly and reduction of weight and size. One example of such a
prior art vehicle wheel bearing apparatus is shown in FIG. 9.
[0004] In this vehicle wheel bearing apparatus, a drive shaft 52,
connected to a differential apparatus (not shown), is inserted into
an axle housing 51. A double row conical roller bearing 53 is
mounted on the axle housing 51. A wheel hub 54 is rotatably
supported by the double row conical roller bearing 53. The wheel
hub 54 is connected to a flange 56 via hub bolts 55. A pair of
inner rings 57 is connected to each other by a connecting ring 58.
The rings 57 are fit onto the end of the axle housing 51 and then
securely fastened by a fastening nut 59. An outer ring 60 of the
double row conical roller bearing is fitted into the wheel hub 54.
The outer ring 60 is axially secured by both its ends being
sandwiched by the flange 56 of the drive shaft 52 and a brake rotor
61. Double row conical rollers 62 are rollably contained by cages
63 between the annular space between the inner and outer rings 57
and 60. Seals 64 are arranged at both ends of the annular space to
seal off the inside of the wheel bearing from the outside.
[0005] The inboard side end of the inner ring 57 is formed with an
annular stepped portion 65. The stepped portion 65 receives and
mounts a seal ring 66. An annular recess 67 is formed on the outer
circumferential surfaces of the inner rings 57 at mutually abutted
portions of the pair of inner rings 57. An elastic seal ring 68 is
fit into the recess 67. These seal rings 66 and 68 prevent
penetration or ingress of rain water or dusts into the axle housing
51, leakage of differential gear oil to the outside and ingress of
the differential gear oil into the inside of the bearing (see
Japanese Laid-open Patent publication No. 99172/2001).
[0006] However since the prior art vehicle wheel bearing apparatus
has a structure where the double row of conical roller bearing 53
is arranged between the wheel hub 54 and the axle housing 51, the
driving shaft 52 is inserted into the axle housing 51 and the
flange 56 of this drive shaft 52 is connected to the wheel hub 54
by the hub bolts 55, a reduction of the weight and size of the
bearing apparatus is limited. Also, the assembly of the bearing
apparatus is complicated due to the requirement of a large number
of structural parts.
SUMMARY OF THE INVENTION
[0007] It is therefore an object of the present disclosure to
provide a vehicle wheel bearing apparatus which can reduce the
weight, size and the number of parts. Also, a bearing apparatus can
prevent the ingress of rain water or dusts and the leakage of
differential gear oil.
[0008] According to the present disclosure, a vehicle wheel bearing
apparatus comprises an axle housing supported under a body of a
vehicle. A hollow drive shaft is inserted into the axle housing. A
wheel bearing is arranged between the drive shaft and an opening of
the axle housing and is structured as a unit of a wheel hub and a
double row rolling bearing. The wheel bearing comprises an inner
member which includes a wheel hub with an integrally formed wheel
mounting flange on one end and an axially extending cylindrical
portion. At least one inner ring is press-fit onto the cylindrical
portion of the wheel hub. The outer circumferential surface of the
inner ring is formed with at least one of the inner raceway
surfaces. An outer member is arranged around the inner member. The
outer member is formed with double row outer raceway surfaces on
its inner circumferential surface. The outer raceway surfaces are
opposite to the inner raceway surfaces. Double row rolling elements
are arranged between the inner and outer raceway surfaces of the
inner member and the outer member. A cage freely rollably holds the
rolling elements. Seals are provided to seal an annular space
between the inner member and the outer member. A cap, with a metal
core formed from steel, is press-fit into an end of a central bore
of the wheel hub.
[0009] Since the cap, with the steel metal core, is press-fit into
an end of the central bore of the wheel hub forming the wheel
bearing apparatus, it is possible to provide a vehicle wheel
bearing apparatus of a semi-floating type which can reduce weight
and size. Also, the bearing apparatus can prevent the leakage of
differential gear oil to the outside as well as prevent the ingress
of rain water or dusts from the outside into the differential gear
oil through the drive shaft.
[0010] Since at least one of the inner raceway surfaces is formed
directly on the outer circumferential surface of the wheel hub, it
is possible to further reduce the bearing weight and size and
increase the rigidity of the bearing.
[0011] Since the end of the cylindrical portion is radially
outwardly plastically deformed to form a caulked portion to prevent
the inner ring from slipping off the cylindrical portion of the
wheel hub, it is unnecessary to control the amount of preload of
the bearing as in the prior art, by tightly fastening a nut on the
inner ring. Thus, the ease of assembly of the bearing apparatus
onto a vehicle can be improved. Also, the predetermined amount of
preload can be kept for a long term. In addition, it is possible to
substantially reduce the number of parts and to reduce
manufacturing cost, weight and size of the bearing due to the
improvements in the ease of assembly.
[0012] Since the outer circumferential region of the wheel mounting
flange, from its base to the inboard side to the cylindrical
portion, is hardened by high frequency induction hardening to have
a surface hardness of 54.about.64 HRC, and the caulked portion
remains unhardened to have a surface hardness of 25 HRC or less
after forging, it is possible to improve the durability of the
wheel hub and workability of the caulked portion during its plastic
deformation. Thus, reliability of the quality of the bearing is
improved.
[0013] Since the cap is press-fit into the central bore of the
wheel hub wheel mounting flange, the cap can be positioned at a
region with high rigidity of the wheel hub. Accordingly, the cap is
scarcely influenced by elastic deformation of the wheel hub and
thus, it is possible to prevent the generation of a radial gap
between the cap and the wheel hub.
[0014] Since the cap includes a metal core made of steel with a
substantially "C" shaped configuration cross-section and an elastic
member is attached to at least part of its fitting portion, the
elastic member can intimately contact the fitting surface and thus
can securely seal the inside of the wheel hub.
[0015] Since the cap is press-fit so that the circumferential edge
of its fitting portion is oriented toward the outboard side, the
press-fitting operation can be easily carried out. In addition,
since the edge side of low rigidity is positioned at the outboard
side, the cap does not move toward the outboard side. Thus,
slipping off of the cap from the wheel hub can be prevented even
though the metal core is moved axially due to its deformation
caused by elastic deformation of the wheel hub.
[0016] Since the circumferential edge of the fitting portion of the
metal core is formed with an extending radially outward bead, and
an annular groove which engages the bead is formed on the central
bore of the wheel hub, it is possible to securely prevent axial
movement of the cap. This further improves the reliability of the
cap.
[0017] Since the cap is limited against axial movement by steps
provided at either side of the cap, it is possible to securely
prevent the cap from slipping off from the wheel hub even though
the wheel hub is elastically deformed by a repeating load applied
to it during running of a vehicle.
[0018] Since the cap includes a metal core made of steel with a
substantially "C" shaped configuration cross section, an annular
recess is formed on the inner circumferential surface of the wheel
hub, and the fitting portion of the cap is formed with a projection
adapted to engage the annular recess, it is possible to easily
mount the cap on the wheel hub and to prevent axial movement of the
cap with a simple structure.
[0019] Since the projection is formed by plastic deformation after
the cap has been press-fit into the bore of the wheel hub, the cap
can be further intimately fitted into the annular groove of the
wheel hub without any rattle. Thus, axial movement of the cap and
also leakage of differential gear oil can be further prevented by
the mating of the projection and bore.
[0020] Since the cap is press-fit with an interference of
0.05.about.0.3 mm, it is possible to prevent the generation of a
radial gap between the cap and the wheel hub due to errors in
configuration of the cap. Thus, this prevents leakage of
differential gear oil therethrough. In addition, the cap can be
easily press-fit into the wheel hub and buckling of the cap, which
would be caused by large interference, can also be prevented.
[0021] The vehicle wheel bearing apparatus of the present
disclosure, which comprises an axle housing supported under a body
of vehicle; a hollow drive shaft inserted into the axle housing; a
wheel bearing arranged between the drive shaft and an opening of
the axle housing which is structured as a unit of a wheel hub and a
double row rolling bearing; the wheel bearing comprises an inner
member with a wheel hub integrally formed with a wheel mounting
flange on one end and having an axially extending cylindrical
portion; at least one inner ring is press-fit onto the cylindrical
portion of the wheel hub and is formed on its outer circumferential
surface with at least one of the inner raceway surfaces; an outer
member is arranged around the inner member and is formed with
double row outer raceway surfaces on its inner circumferential
surface opposite to the inner raceway surfaces; double row rolling
elements are arranged between the inner and outer raceway surfaces
of the inner member and the outer member; a cage freely rollably
holds the rolling elements; and seals seal an annular space between
the inner member and the outer member; a cap, with a metal core of
steel, is press-fit into an end of a central bore of the wheel hub,
makes it possible to provide a vehicle wheel bearing apparatus of a
semi-floating type which can reduce the weight and size of the
bearing apparatus. Also, it prevents leakage of differential gear
oil to the outside as well as the ingress of rain water or dusts
from the outside into the differential gear oil through the drive
shaft.
[0022] According to the disclosure, a vehicle wheel bearing
apparatus comprises an axle housing supported under a body of the
vehicle. A hollow drive shaft is inserted into the axle housing. A
wheel bearing is arranged between the drive shaft and an opening of
the axle housing. The wheel bearing is structured as a unit with a
wheel hub and a double row rolling bearing. The wheel bearing has
an inner member which includes a wheel hub integrally formed with a
wheel mounting flange on one end and an axially extending
cylindrical portion. At least one inner ring is press-fit onto the
cylindrical portion of the wheel hub. The inner ring outer
circumferential surface is formed with at least one inner raceway
surfaces. An outer member is arranged around the inner member. The
outer member is formed with double row outer raceway surfaces on
its inner circumferential surface opposite to the inner raceway
surfaces. Double row rolling elements are arranged between the
inner and outer raceway surfaces of the inner member and the outer
member. A cage freely rollably holds the rolling elements. Seals
seal an annular space between the inner member and the outer
member. A cap, with a metal core of steel, is press-fit into an end
of a central bore of the wheel hub.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Additional advantages and features of the present disclosure
will become apparent from the subsequent description and the
appended claims, taken in conjunction with the accompanying
drawings, wherein:
[0024] FIG. 1 is a longitudinal-section view of a first embodiment
of a vehicle wheel bearing apparatus;
[0025] FIG. 2 is a partially enlarged longitudinal-section view of
FIG. 1;
[0026] FIG. 3 is a longitudinal-section view of a second embodiment
of a vehicle wheel bearing apparatus;
[0027] FIG. 4 is a partially enlarged longitudinal-section view of
FIG. 3;
[0028] FIG. 5 is a longitudinal-section view of a third embodiment
of a vehicle bearing apparatus;
[0029] FIG. 6 is a longitudinal-section view of a fourth embodiment
of a vehicle wheel bearing apparatus;
[0030] FIGS. 7(a) and 7(b) are a partially enlarged
longitudinal-section view of a modification of the fourth
embodiment showing, respectively, a condition of a cap before and
after caulking;
[0031] FIG. 8 is a longitudinal-section view of a fifth embodiment
of a vehicle wheel bearing apparatus; and
[0032] FIG. 9 is a longitudinal-section view of a prior art vehicle
wheel bearing apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Preferred embodiments of the present disclosure will be
described with reference to the accompanying drawings.
[0034] FIG. 1 is a longitudinal-section view of a first embodiment
of a vehicle wheel bearing apparatus. FIG. 2 is a partially
enlarged longitudinal-section view of FIG. 1. In the present
description, a side of the bearing positioned outward of a vehicle,
when it is mounted on the vehicle, is referred to as the "outboard"
side (the left side in a drawing). A side inward of the vehicle is
referred to as the "inboard" side (the right side in a
drawing).
[0035] In the vehicle wheel bearing apparatus, a wheel hub 1 and a
double row rolling bearing 2 are formed as a unit and are connected
to a drive shaft "D/S". The double row rolling bearing 2 includes
an inner member 3, an outer member 4, and double row rolling
elements (tapered rollers) 5 freely rollably contained between the
inner and outer members 3 and 4. The inner member 3 includes the
wheel hub 1 and a pair of inner rings 10 press-fit onto the wheel
hub 1. The wheel hub 1 is integrally formed, at its outboard side,
with a wheel mounting flange 6 on which, a wheel "W" and a brake
rotor "B" are mounted. An axially extending cylindrical portion 7
extends from the flange 6. An inner circumferential surface (bore)
of the wheel hub 1 is formed with a serration (or spline) 8 to
receive a serrated portion of the drive shaft "D/S" to transmit
torque between the two.
[0036] As shown in FIG. 2, the double row rolling bearing 2
includes an outer member 4 formed with double row outer raceway
surfaces 4a on its inner circumferential surface. A body mounting
flange 4b is formed on the outer member 4. The flange 4b is to be
secured on an axle housing "H" on its outer circumferential
surface. A pair of inner rings 10 are inserted into the outer
member 4. The inner rings 10 are formed with double row tapered
inner raceway surfaces 10a, 10a on their outer circumferential
surface opposite to the outer raceway surfaces 4a. Double row
rolling elements 5 are arranged between the inner and outer raceway
surfaces 10a, 4a. A cage 11 freely rollably holds the rolling
elements 5. Each of the inner rings 10 is formed with, at its
larger diameter end, a large flange 10b to guide the rolling
elements 5. The pair of inner rings 10 is arranged so that their
inner ends abut each other. Thus, they form a so-called
back-abutted type double row tapered roller bearing. Seals 12 are
arranged at both ends of the outer member 4 to seal an annular
space between the outer member 4 and the inner rings 10. The seals
12 prevent both penetration of rain water or dusts from external
circumstances and leakage of lubricating grease sealed within the
bearing. The inboard side seal 12 further prevents penetration or
ingress of differential gear oil into the inside of the
bearing.
[0037] The pair of inner rings 10 are press-fit onto the
cylindrical portion 7 of the wheel hub 1. The inner rings 10 are
prevented from axially slipping off of the cylindrical portion 7 by
a caulked portion 13. The caulked portion is formed by plastically
deforming the end of the cylindrical portion 7 radially outward.
Since this embodiment adopts the self-retaining structure of the
second generation, it is not required to control an amount of
preload as in a conventional manner by tightly fastening a nut
against the inner ring. Accordingly, it is possible to
substantially reduce the number of parts and thus to improve the
readiness of assembly as well as to reduce its manufacturing cost,
size and weight.
[0038] The wheel hub 1 is made of medium carbon steel such as S53C
which includes carbon of 0.40.about.0.80% by weight. The wheel hub
1 is hardened by high frequency induction quenching so that the
base of the wheel mounting flange 6, at its inboard side, and the
cylindrical portion 7 of the wheel hub 1 have a surface hardness of
54.about.64 HRC (the hardened portion is shown in drawings by
cross-hatched lines). The caulked portion 13 remains as an
unhardened portion and has its surface hardness of 25 HRC or less.
This improves the durability and workability of the caulked portion
13 and also prevents the generation of cracks.
[0039] The outer member 4 is also made of medium carbon steel such
as S53C which includes carbon of 0.40.about.0.80% by weight. The
double row outer raceway surfaces 4a and inner circumferential
surface of the outer member 4, on which the seal 12 is mounted, are
hardened by high frequency induction quenching so that their
surface hardness is within 54.about.64 HRC. The inner rings 10 are
made of high carbon chrome bearing steel such as SUJ2. The inner
rings 10 are hardened to the core by dip quenching to have a
surface hardness of HRC 54.about.64. Even though the double row
tapered roller bearing is illustrated using tapered roller as the
rolling elements 5, a double row angular ball bearing using balls
may also be used.
[0040] In this embodiment, a cap 9 is press-fit into an opening of
the wheel hub 1 at its outboard side. This cap 9 is made of
austenitic-stainless steel sheet (JIS SUS 304 etc.) or preserved
cold rolled steel sheet (JIS SPCC etc.) and is formed as an annular
shape by press working. The cap 9 includes a metal core 9a formed
from steel. The cap 9 has a substantially "C"-shaped cross-section.
An elastic member 9b, of rubber, is bonded, via vulcanization, to
at least the fitting portion of the metal core 9a. The elastic
member 9b is elastically deformed during the press fitting of the
cap 9 into the opening of the wheel hub 1 to seal the opening. The
seal surely prevents ingress of rain water or dusts from the
ambient circumstances into the drive shaft "D/S" and thus into the
differential gear oil.
[0041] It is preferable that the cap 9 is press-fit into the wheel
hub 1 with a interference of 0.05.about.0.3 mm. This is because the
differential gear oil could leak through a small radial gap which
would be caused in the fitting portion between the wheel hub 1 and
the cap 9 due to dimensional errors of the cap itself when the
interference is less than 0.05 mm. On the other hand, the
press-fitting operation of the cap 9 becomes difficult and buckling
of the metal core may occur when the interference is larger than
0.3 mm. In addition, it is preferable that the cap 9 is press-fit
into the wheel hub 1 at a high rigid bore portion. That is, a bore
portion of the wheel hub 1 at or near the wheel mounting flange 6.
Accordingly, the cap 9 is scarcely influenced by elastic
deformation of the wheel hub 1 even though the wheel hub 1 would be
deformed by applying repeated moment loads.
[0042] FIG. 3 is a longitudinal-section view of a second embodiment
of the vehicle wheel bearing apparatus. Since the difference
between this embodiment and the first embodiment only resides in
the structure of the wheel hub, the same numerals are used as those
used in the first embodiment to designate the same structural
elements.
[0043] The vehicle wheel bearing apparatus is structured as a unit
with the wheel hub 14 and a double row rolling bearing 15. The
double row rolling bearing 15 includes an inner member 16, an outer
member 4, and a double row rolling elements 5 and 5 freely rollably
contained between the inner and outer members 16 and 4. The inner
member 16 includes the wheel hub 14 and the inner ring 10 press-fit
onto the wheel hub 14. The wheel hub 14 is integrally formed, at
its outboard side, with a wheel mounting flange 6 on which, a wheel
(not shown in FIG. 3) is mounted. An inner raceway surface 14a is
formed on the wheel hub 14 on the outboard side of the bearing 15.
Also, the wheel hub 14 has the cylindrical portion 7 axially
extending from the inner raceway surface 14a. The wheel hub 14 is
formed with a serration (or spline) 8 on its inner circumferential
surface (bore) to receive a serrated portion of the drive shaft
(not shown in FIG. 3) to transmit torque between the two.
[0044] The outer circumferential surface of the wheel hub 14 is
formed with a flange portion 14b, corresponding to the large flange
10b of the inner ring 10, and a stepped portion 14c, which abuts an
inner end face (smaller end face). Thus, the so-called back-abutted
type double row tapered roller bearing is formed. In addition, the
inner ring 10 is press-fit onto the cylindrical portion 7 of the
wheel hub 14. The inner ring 10 is prevented from axially slipping
off of the cylindrical portion 7 by a caulked portion 13. The
caulked portion 13 is formed by plastically deforming the end of
the cylindrical portion 7 radially outward. Since this embodiment
adopts a self-retaining structure of such a third generation, it is
not required to control an amount of preload in a manner similar to
the first embodiment by tightly fastening a nut against the inner
ring. Accordingly, it is possible to improve the readiness of
assembly as well as to maintain the amount of preload for a long
term.
[0045] Since the inner raceway surface 14a is directly formed on
the outer circumferential surface of the wheel hub 14, the rigidity
of the wheel hub 14 is increased. Accordingly, it is possible to
reduce the size and weight of the bearing apparatus and to improve
it even though the wheel hub 14 would be deformed by an moment load
applied during running of the vehicle.
[0046] A cap 17 is press-fitted into an opening of the wheel hub 14
at its outboard side. The cap 17 is made of austenitic-stainless
steel sheet (JIS SUS 304 etc.) or preserved cold rolled steel sheet
(JIS SPCC etc.) and includes a metal core 18. The cap 17 is formed
to have a substantially "C"-shaped cross-section. An elastic member
19, of rubber, is bonded via vulcanization, to the outer surface of
the metal core 18. The metal core 18 is press-fit into the wheel
hub 14 so that the circumferential edge of the cylindrical fitting
portion 18a is oriented toward the outboard side. This makes the
press-fitting operation of the cap 17 easy. In addition, since the
edge portion of the cap 17, having low rigidity, is positioned at
the outboard side, the cap 17 does not move toward the outboard
side. Thus, it is possible to prevent the cap 17 from slipping off
the wheel hub 14 even though the metal core 18 is deformed due to
the elastic deformation of the wheel hub 14.
[0047] As clearly shown in FIG. 4, a bead 18b is formed at the
circumferential edge. The bead 18b extends radially outward. It is
possible to securely prevent axial movement of the cap 17 by
engaging the bead 18b with an annular groove 20 formed on the inner
circumferential surface (bore) of the wheel hub 14.
[0048] FIG. 5 is an enlarged partial view of a third embodiment of
a vehicle wheel bearing apparatus. The same numerals are used as
those in the previous embodiments to designate the same structural
elements.
[0049] In this embodiment, a cap 21 is press-fit into an opening of
the wheel hub 1 at its outboard side. The cap 21 is made of
austenitic-stainless steel sheet (JIS SUS 304 etc.) or preserved
cold rolled steel sheet (JIS SPCC etc.) and includes a metal core
21a formed from steel. The cap 21 has a substantially "C"-shaped
cross-section. An elastic member 21b extended from the inner
circumferential surface to the cylindrical fitting portion of the
metal core 21b. The elastic member 21b is formed from a material
such as rubber bonded, via vulcanization, to the surface of the
metal core 21a. The elastic member 21b functions to prevent the
generation of rust on the metal core 21a and seals the inside of
the wheel hub 1 from the outside with intimate contact of the
elastic member 21b to the inner circumferential surface (bore) of
the wheel hub 1. Accordingly, it is possible to prevent ingress of
rain water or dusts from ambient circumstances into the drive shaft
and thus into the differential gear oil. Also, it is possible to
prevent leakage of the differential gear oil to the outside.
[0050] The axial movement of the cap 21 is limited by a stop ring
22 secured on the inner circumferential surface of the wheel hub 1,
and a stepped portion 23. Thus, it is possible to prevent the cap
21 from slipping off the wheel hub 1 even though the wheel hub 1 is
deformed by the repeated moment load applied during running of the
vehicle. Projections 24, co-axially formed on the metal core 21a,
increase the rigidity of the metal core 21a and improve the
buckling resistance.
[0051] FIG. 6 is an enlarged partial view of a fourth embodiment of
the vehicle wheel bearing apparatus. The same numerals are used as
those used in the previous embodiments to designate the same
structural elements.
[0052] In this embodiment, an annular recess 25, having a circular
arc cross section, is formed on the inner circumferential surface
(bore) of the wheel hub 1. A cap 26 is formed with a projection 26a
having a cross section corresponding to the annular recess 25. The
cap 26 is snapped into the recess 25. This makes the mounting of
the cap 26 easy and also prevents axial movement of the cap 26 with
a simple structure. In this case, it is unnecessary to form the
projection 26a on the whole circumference of the cap 26. Thus,
three or more projections will sufficiently perform this
function.
[0053] FIG. 7 is a partially enlarged longitudinal-section view of
a modification of the fourth embodiment. The same numerals are used
as those used in the previous embodiment (FIG. 6) to designate the
same structural elements.
[0054] A cap 27' has a substantially "C"-shaped configuration cross
section and is press-fit into the inner circumferential surface
(bore) of the wheel hub 1 with a predetermined interference. The
cap 27' is plastically deformed by a rolling tool and fitted into
the annular recess 25. The formed projection 26a can further
intimately contact the annular recess 25 of the wheel hub 1 without
rattle. Accordingly, it is possible to further effectively prevent
axial movement of the cap 27' and to securely prevent leakage of
the differential gear oil by this projection 26a in cooperation
with the fitting portion 26b.
[0055] FIG. 8 is an enlarged partial view of a fifth embodiment of
the vehicle wheel bearing apparatus. The same numerals are used as
those used in the previous embodiments to designate the same
structural elements.
[0056] In this embodiment, a cap 29 is press-fit into the wheel hub
1 over a region of the inner circumferential surface (bore) from
its opened end at the outboard side to a pilot portion 28. The cap
29 is made of austenitic-stainless steel sheet (JIS SUS 304 etc.)
or preserved cold rolled steel sheet (JIS SPCC etc.). The cap 29
includes a metal core 29a press-formed to have a substantially
"hat"-shaped cross-section. An elastic member 29b, of rubber, is
bonded, via vulcanization, over a region of the metal core 29a from
the outer circumferential surface to the fitting portion and the
outboard side end of the wheel hub 1.
[0057] The elastic member 29b is formed of rubber etc. and is
bonded to the metal core 29a, via vulcanization, and can prevent
leakage of differential gear oil and ingress of rain water or dusts
into the differential gear oil through the drive shaft. In
addition, since the cap 29 closes the whole opened portion of the
wheel hub 1 and it is press-fit into the portion of the wheel hub 1
which is less deformed even though the repeated moment load is
applied to the wheel hub 1, it is possible to further prevent the
elastic deformation of the cap 29 and its slipping off from the
wheel hub 1.
[0058] The vehicle wheel bearing apparatus can be applied to the
driving wheel side of the semi-floating type where a wheel bearing
is arranged in opened portions between a drive shaft and a axle
housing.
[0059] The present disclosure has been described with reference to
the preferred embodiment. Obviously, modifications and alternations
will occur to those of ordinary skill in the art upon reading and
understanding the preceding detailed description. It is intended
that the present disclosure be construed as including all such
alternations and modifications insofar as they come within the
scope of the appended claims or their equivalents.
* * * * *