Constant velocity joint and rolling bearing unit for wheel

Details Constant velocity joint and rolling bearing unit for wheel Constant velocity joint and rolling bearing unit for wheel

1999-04-15

2001-10-09

Browne, Lynne H. (Department: 3629)

Rotary shafts, gudgeons, housings, and flexible couplings for ro

Coupling accommodates drive between members having...

Coupling transmits torque via radially spaced ball

C464S139000, C464S906000

Reexamination Certificate

active

06299542

ABSTRACT:

This application claims the benefits of Japanese Application Nos. 10-104885, 10-120383, 10-206249 and 10-226142 which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a constant velocity joint and a wheel-support rolling bearing unit incorporating the constant velocity joint.
A wheel-support rolling bearing unit according to the present invention is a so-called fourth-generation hub unit, and utilized for supporting the drive wheels {(which imply front wheels of an FF car (front-engine front-drive car), rear wheels of an FR car (front-engine rear-drive car) of an RR car (rear-engine rear drive car), and whole wheels of 4WD car (four-wheel drive car)} held on the independent suspension so that the drive wheels are rotatable about the suspension.
A constant velocity joint according to the present invention is integrally incorporated into a rolling bearing unit for supporting drive wheels on, e.g., an independent suspension, and utilized for transmitting a driving force from a transmission to the drive wheels.
2. Related Background Art
A constant velocity joint is provided between a transmission of an automobile and a drive wheel supported on an independent suspension, whereby a driving force (traction) of an engine is transmittable to the drive wheel at the same angular speed along an entire periphery irrespective of a relative displacement between a differential gear and the drive wheel and of a steering angle given to the wheel. What has hitherto been known as the constant velocity joint used for such a mechanism, is disclosed, e.g., U.S. Pat. No. 3,324,682, U.S. Pat. No. 3,412,580 and U.S. Pat. No. 4,589,857.
This type of constant velocity joint
1
which has been known so far is constructed so that a rotary force is, as shown in, e.g.,
FIGS. 21-23
, transmitted between an inner race
2
and an outer race
3
through six pieces of balls
4
,
4
. The inner race
2
is fixed to an external side end (a left side end in
FIG. 21
) of one shaft
5
rotationally driven by the transmission. Further the outer race
3
is fixed to an internal side end (a right side end in
FIG. 21
) of another shaft
6
for fixing the drive wheel. Six streaks of inner engagement grooves
7
,
7
each taking a circular arc shape in section are formed in an outer peripheral surface
2
a
of the inner race
2
in a direction right-angled to a circumferential direction at an equal interval in the circumferential direction. Six streaks of outer engagement grooves
8
,
8
each taking the circular arc shape in section are likewise formed in an outer peripheral surface
3
a
of the outer race
3
in positions facing to the inner engagement grooves
7
,
7
in the direction right-angled to the circumferential direction.
A cage
9
assuming a circular arc shape in section but an annular shape on the whole is sandwiched in between the outer peripheral surface
2
a
of the inner race
2
and the inner peripheral surface
3
a
of the outer race
3
. Pockets
10
,
10
are formed in positions aligned with the two groups of inner and outer engagement grooves
7
,
8
as well as in six positions in the circumferential direction of the cage
9
, and totally six pieces of balls
4
,
4
are held one by one inwardly of each of the pockets
10
,
10
. These balls
4
,
4
are capable of rolling along the two groups of inner and outer engagement grooves
7
,
8
in a state of being held in the pockets
10
,
10
.
The pockets
10
,
10
are, as illustrated in
FIG. 23
, each takes a rectangular shape elongated in the circumferential direction, and structured to, even when a spacing between the balls
4
,
4
adjacent to each other in the circumferential direction might change with a variation in an axial crossing angle &agr; which will hereinafter be explained, absorb this change. Namely, a positional relationship between bottom surfaces
7
a
,
7
a
of the inner engagement grooves
7
,
7
and a positional relationship between bottom surfaces
8
a
,
8
a
of the outer engagement grooves
8
,
8
, become such as a relationship of the longitude lines on a globe as indicated by the one-dotted chain line in FIG.
24
. If the central axis of the inner race
2
is concentric with the central axis of the outer race (the axial crossing angle &agr;=180°), each of the balls
4
,
4
exists in the vicinity of a position corresponding to the equator on the globe which is indicated by the two-dotted line in FIG.
24
. Whereas if the central axis of the inner race
2
is not concentric with the central axis of the outer race (the axial crossing angle &agr;<180°), the balls
4
,
4
displace in reciprocation (displace alternately in the direction of the North Pole and in the direction of the South Pole on the globe) in the up-and-down direction in
FIG. 24
with a rotation of the constant velocity joint
1
. As a result, the spacing between the balls
4
,
4
adjacent to each other in the circumferential direction changes, and hence the pockets
10
,
10
each takes the rectangular shape elongated in the circumferential direction, thereby enabling the spacing therebetween to change. Note that the bottom surfaces
7
a
,
7
a
of the inner engagement grooves
7
,
7
and the bottom surfaces
8
a
,
8
a
of the outer engagement grooves
8
,
8
, are not concentric with each other as obvious from the explanation which follows. Accordingly, the lines corresponding to the longitude lines exist in positions slightly deviating from each other for every corresponding engagement groove
7
or
8
.
Further, as shown in
FIG. 21
, the balls
4
,
4
are disposed within a bisection plane c which bisects the axial crossing angle &agr; between the two shafts
5
,
6
, i.e., the angle &agr; made by two lines a and b at a point-of-intersection O between a central line a of one shaft
5
and a central line b of the other shaft
6
. Therefore, the bottom surfaces
7
a
,
7
a
of the inner engagement grooves
7
,
7
are located on a spherical surface wherein a point d existing away by h from the point-of-intersection O on the central line a is centered, and the bottom surfaces
8
a
,
8
a
of the inner engagement grooves
8
,
8
are located on a spherical surface wherein a point e existing away by h from the point-of-intersection o on the central line b is centered. The outer peripheral surface
2
a
of the inner race
2
, the inner peripheral surface
3
a
of the outer race and two inner and outer peripheral surfaces of the cage
9
, are, however, located on the spherical surface with the point-of-intersection O being centered, thereby enabling the outer peripheral surface
2
a
of the inner race
2
and the inner peripheral surface of the cage
9
to slide on each other, and also the outer peripheral surface
3
a
of the outer race
3
and the outer peripheral surface of the cage
9
to slide on each other.
In the case of the thus constructed constant velocity joint
1
, when the inner race
2
is rotated by one shaft
5
, this rotary motion is transmitted via the six balls
4
,
4
to the outer race
3
, whereby the other shaft
6
rotates. If a positional relationship (which implies the axial crossing angle &agr;) between the two shafts
5
,
6
changes, the balls
4
,
4
roll along the two groups of inner and outer engagement grooves, thus allowing the displacement between one shaft
5
and the other shaft
6
.
The basic structure and operation of the constant velocity joint are as described above. The basic structure and operation of the constant velocity joint which have been explained referring to
FIG. 21
are applied to the present invention and the embodiments thereof which will be discussed later on.
On the other hand, it has been a technical pursuit over the recent years that the constant velocity joint described above is combined integrally with a wheel-support rolling bearing unit for rotatably supporting the wheel on a suspension. Namely, the operation of rotatably supporting the wheel of an automobile on the suspension involves the use of

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