Tripod type constant velocity joint

Details Tripod type constant velocity joint Tripod type constant velocity joint

1998-09-11

2001-04-17

Knight, Anthony (Department: 3629)

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

Coupling accommodates drive between members having...

Tripod coupling

C464S124000

Reexamination Certificate

active

06217454

ABSTRACT:

FIELD OF THE INVENTION
The present invention is related to a tripod type constant velocity joint incorporated into a drive system of an automobile or the like, for effecting transmission of a rotational force between a pair of non aligned rotating shafts.
DESCRIPTION OF THE RELATED ART
Tripod type constant velocity joints have been widely used in the past as one type of constant velocity joint incorporated into automobile drive systems. For example Japanese Unexamined Patent Publication KOKAI Nos. 63-186036, and 62-233522, disclose a tripod type constant velocity joint
1
as shown in
FIGS. 1 and 2
where some internal parts are depicted by dotted lines in FIG.
1
. Such a constant velocity joint
1
comprises a hollow cylindrical housing
3
which is secured to an end of a first rotating shaft
2
such as the rotating shaft on the wheel side, and a tripod
5
which is connected to an end of a second rotating shaft
4
such as a drive shaft.
Recesses
6
are formed at three locations on the inner peripheral surface of the housing
3
at even spacing around the circumferential direction, and recessed from the respective inner peripheral faces in the radially outward direction of the housing
3
.
The tripod
5
connected to the end of the second rotating shaft
4
comprises a boss
7
for attachment to the end of the second rotating shaft
4
, and trunnions
8
formed at three locations on the outer peripheral face of the boss
7
at even spacing therearound and formed as cylindrical posts. Around each of the respective trunnions
8
, a roller
9
is supported by means of needle bearing
10
so as to be freely rotatable thereabout, and so as to be able to move slightly in the axial direction.
Moreover, the constant velocity joint
1
is assembled by engaging the respective rollers
9
in the recesses
6
on the inner peripheral surface of the housing
3
. Respective pairs of inner surface
11
which partly define the respective recesses
6
, are formed respectively in an arcuate shape. Consequently, the respectively rollers
9
are supported so as to be able to move and slide freely between the pairs of inner surfaces
11
.
When using a constant velocity joint
1
of the abovementioned construction, then for example, as the second rotating shaft
4
rotates, the rotational force is transmitted from the boss
7
of the tripod
5
via the trunnions
8
, the needle bearings
10
and the rollers
9
to the housing
3
, so that the first rotating shaft
2
which is fixed at an end thereof to the housing
3
, is rotated.
On the other hand, as the first rotating shaft
2
rotates, the rotational force is transmitted from the housing
3
, via the rollers
9
, the needle bearings
10
and the trunnions
8
to the boss
7
of the tripod
5
, so that the second rotating shaft
4
fixed at an end thereof to the boss
7
is rotated.
Furthermore, in the case where the axis of the first rotating shaft
2
and the axis of the second rotating shaft
4
are out of alignment, in other words, when the constant velocity joint
1
has a joint angle, then the trunnions
8
swing about the boss
7
of the tripod
5
accompanying rotation of the first and second rotating shafts
2
and
4
as shown in
FIGS. 1 and 2
, so that the trunnions
8
are displaced relative to the inner side faces
11
of the respective recesses
6
. At this time, the rollers
9
supported on the respective trunnions
8
roll on the inner surfaces of the respective recesses
6
, and move axially along the respective trunnions
8
. Due to these movements, the constant velocity characteristic is maintained between the first and second rotating shafts
2
and
4
as well known in the art.
In the case of the constant velocity joint
1
constructed and operated as described above, when the first and second rotating shafts
2
and
4
are rotated with a joint angle therebetween, the respective rollers
9
carry out a complicated movement. That is to say, in this condition the respective rollers
9
move in the axial direction of the housing
3
along the inner side faces
11
of the recesses
6
while their orientation changes, and also move axially along the trunnions
8
. When the rollers
9
are subjected to this complicated movement, the relative displacement between the outer peripheral faces of the rollers
9
and the inner side faces
11
of the recesses is not always carried out smoothly, so that a relatively large force, referred to as “axial force”, is produced between the faces. As a result, in the case of the constant velocity joint of the construction shown in
FIGS. 1 and 2
, then three axial forces are produced for each rotation. Furthermore, then in exceptional cases, e.g. when fitted to an automobile with for example a large torque being transmitted under large joint angle conditions, a vibration known as shudder can occur.
The constant velocity joint
1
shown in
FIGS. 3 through 5
is disclosed in Japanese Unexamined Patent Publication KOKAI No. 63-186036, as a construction to suppress vibrations arising from the above cause. In the case of this improved type constant velocity joint
1
, instead of the rollers
9
in
FIGS. 1 and 2
, a set of inner rollers
12
and outer rollers
13
are provided on the respective trunnions
8
.
The inner rollers
12
are respectively formed with cylindrical inner peripheral faces and spherical convex outer peripheral faces, and are supported on bearings
14
so as to be only rotatable about the respective trunnions
8
. Moreover, the outer rollers
13
are formed with cylindrical inner peripheral faces so that the inner rollers
12
are engaged thereinside, such that the inner rollers
12
are able to swing and be displaced in the axial direction of the respective outer rollers
13
.
Moreover, provided in pairs for each of the recesses
6
on the inner peripheral surface of housing
3
are guide faces
15
with which the outer peripheral faces of the outer rollers
13
are in rolling contact, so as to move only in the axial direction of housing
3
(left and right directions in FIG.
3
and
FIG. 5
, the front and rear directions in FIG.
4
).
With the improved constant velocity joint
1
constructed as described above, the displacement of the set of rollers
12
,
13
in the axial direction of the housing
3
, is permitted by rotation of the outer rollers
13
. Moreover, the swinging or rocking of the set of rollers
12
,
13
about the center of the tripod
5
, and the displacement along the axial direction of the trunnions
8
, are permitted by the swinging or rocking and sliding of the inner rollers
12
relative to the respective outer rollers
13
. This displacement of the outer peripheral faces of the respective outer and inner rollers
13
and
12
relative to the mating faces is simpler than the displacement of the rollers
9
in the construction of
FIGS. 1 and 2
, relative to the inner side faces
11
of the recesses
6
and the trunnions
8
, so that stabilized displacement is carried out in the construction in
FIGS. 3 through 5
. Consequently, the shaft force produced with rotation of the constant velocity joint is reduced, so that even when a large torque is transmitted with a large joint angle, the occurrence of uncomfortable vibrations can be suppressed.
In the case of the second example of the conventional construction shown in
FIGS. 3 through 5
, the vibration can be suppressed by reducing the axial force, however there is room for improvement from the point of maintaining durability. That is to say, in the case of the tripod type constant velocity joint to which the present invention is addressed, then it is necessary for the outer peripheral faces of the set of rollers
12
,
13
to move in the axial direction of the respective trunnions
8
. Therefore, in the case of the construction of the second example, the inner peripheral faces of the outer rollers
13
are made cylindrical, and the spherical convex outer peripheral faces of the inner rollers
12
are engaged with the cylindrical inner peripheral faces of the rollers
13
so as to be able to swing and

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