Tripod type constant velocity universal joint

Details Tripod type constant velocity universal joint Tripod type constant velocity universal joint

1999-12-20

2001-07-24

Browne, Lynne H. (Department: 3629)

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

Coupling accommodates drive between members having...

Tripod coupling

C464S905000

Reexamination Certificate

active

06264565

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a tripod type constant velocity universal joint for use in, but not exclusively, a front-wheel drive automobile.
An example of the tripod type constant velocity universal joint for transmission of torque from a driveshaft of a front-wheel drive automobile to a front wheel at a constant velocity is shown in
FIGS. 9A
to
9
C. The joint shown comprises a cup-shaped outer joint member
1
having three axially extending part-cylindrical guide grooves
2
equally spaced in its inner periphery and an inner joint member, or tripod member,
4
inserted in the outer joint member and having three trunnions
5
projecting radially outwardly of the inner joint member
4
. A roller
7
is rotatably carried by each trunnion
5
through a series of rolling elements
6
and is received in the corresponding guide groove
2
of the outer joint member
1
. The guide groove
2
forms a pair of circumferentially opposing track surfaces
3
parallel to a rotational axis of the outer joint member. An outer periphery of the roller
7
in section is convex and complementary to the track surface
3
. Each roller
7
is movable within the corresponding guide groove
2
while rolling along the track surfaces
3
and rotating about the trunnion
5
.
When the joint transmits torque with the outer and inner joint members
1
and
4
at a working angle of &thgr; as shown in
FIG. 9B
, the roller
7
tilts relative to the track surface
3
as shown in FIG.
9
C. In this case, the roller
7
is about to roll in the direction indicated by arrow t in
FIG. 9B
, but since the track surface
3
extends parallel to the axis of the outer joint member, the roller
7
actually has to slide while being restrained by the track surface
3
. This leads to scuffing of the roller
7
as it moves along the track surface
3
, producing not only frictional heat but also a greater frictional resistance and accordingly an induced thrust in the axial direction. Such induced thrust causes vibration and noise of the car body, and should preferably be reduced as much as possible.
In the tripod type constant velocity universal joint various attempts have been made to reduce the induced thrust, and some examples are shown in
FIG. 10
to FIG.
12
.
FIG. 10
shows a dual-roller arrangement in which an inner roller
11
is rotatably fitted externally on a cylindrical outer periphery of a trunnion
5
a
of an inner joint member
4
a
through a plurality of rolling elements
6
a
, and a cylindrical inner periphery of an outer roller
12
is rotatably fitted externally on an outer periphery of the inner roller
11
. The outer periphery of the inner roller
11
is a truly part-spherical surface having its center on the axis of the trunnion
5
a
, and the inner periphery of the outer roller
12
slides on this truly part-spherical surface, so that the outer roller
12
is tiltable relative to the trunnion
5
a
. The outer roller
12
is received in a guide groove
2
a
of an outer joint member la, and is movable axially of the outer joint member while rolling along track surfaces
3
a
of the guide groove
2
a
. When the joint transmits torque with the outer and inner joint members la and
4
a
at a working angle, the trunnion
5
a
together with the inner roller
11
tilts relative to the outer roller
12
, while the outer roller
12
is guided by the track surfaces
3
a
of the outer joint member
1
a
so as to keep a position parallel to the axis of the outer joint member
1
a
, correctly rolling along the track surfaces
3
a
. Therefore, the frictional resistance and induced thrust are reduced to a certain extent.
In the joint shown in
FIG. 11
, an outer periphery of a trunnion
5
b
of an inner joint member
4
b
is substantially part-spherical, and an annular roller
13
is rotatably and tiltably fitted externally on this part-spherical outer periphery through a plurality of rolling elements
6
b
. When this joint transmits torque with the outer and inner joint members
1
b
and
4
b
at a working angle, the trunnion
5
b
tilts relative to the roller
13
, while the roller
13
is guided by track surfaces
3
b
at opposite sides of a guide groove
2
b
of the outer joint member
1
b
so as to keep a position parallel to the axis of the outer joint member
1
b
, correctly rolling along the track surfaces
3
b
. In this case, too, the frictional resistance and induced thrust are reduced to a certain extent.
The basic structure of the joint shown in
FIG. 12
is the same as that of the joint shown in
FIG. 11
, that is, an outer periphery of a trunnion
5
c
of an inner joint member
4
c
is truly part-spherical, and an annular roller
14
is rotatably and tiltably fitted externally on this truly part-spherical periphery through a plurality of rolling elements
6
c
. In this joint, too, when transmitting torque with the outer and inner joint members
1
c
and
4
c
at a working angle, the trunnion
5
c
tilts relative to the roller
14
, while the roller
14
is guided by track surfaces
3
c
at opposite sides of a guide groove
2
c
of the outer joint member
1
c
so as to keep a position parallel to the axis of the outer member
1
c
, correctly rolling along the track surfaces
3
c
, and therefore the frictional resistance induced thrust are reduced to a certain extent.
In the known arrangements as mentioned above, however, as the joint rotates for transmission of torque between the outer and inner joint members and the roller of the inner joint member moves along the corresponding guide groove of the outer joint member, the roller is pressed against either one of the track surfaces at opposite sides of the guide groove, which can cause the roller to tilt as viewed in a cross section perpendicur to the axis of the outer joint member between the track surfaces. This will now be described in relation to the outer roller
12
of the joint shown in FIG.
10
. As shown in
FIG. 13
which is an enlarged view in part of
FIG. 10
, when torque is transmitted as the roller
12
is relatively pressed against the left track surface
3
L, there is a slight clearance between the roller
12
and the right track surface
3
R. Accordingly, the non-load side
12
n
diametrically opposite to the loaded side
12
m
of the roller
12
can be raised or lowered, with the fulcrum at the outer peripheral central part P.
When the roller
12
tilts radially outwardly of the outer joint member
1
a
as indicated by solid line in
FIG. 13
, the roller
12
comes in contact with a shoulder
8
a
formed in the guide groove
2
a
at its end surface on the non-loaded side
12
n
, producing a frictional resistance. The shoulders
8
a
extend parallel to the axis of the outer joint member along the right and left track surfaces
3
R and
3
L in order to prevent the roller
12
from tilting within the guide groove in the plane including the axis of the outer joint member. Similar shoulders are provided as required in the joints of FIG.
11
and FIG.
12
. On the contrary, when the roller
12
tilts radially inwardly of the outer joint member
1
a
as indicated by chain line in
FIG. 13
, the outer periphery of the roller on the non-load side
12
n
comes in contact with the right track surface
3
R as at S, where a frictional resistance is produced.
The frictional resistance caused by the tilting of the roller
12
is considered to be one of the causes for worsening the induced thrust or slide resistance in the tripod type constant velocity universal joint, and should desirably be reduced as much as possible. However, its reduction has heretofore been limited to such an extent that accuracy in manufacturing and assembling parts permits. Similar problems can also arise in the roller
13
in the joint of
FIG. 11
or the roller
14
in the joint of FIG.
12
.
It is hence a primary object of the invention to provide a tripod type constant velocity universal joint with the induced thrust and slide resistance substantially reduced by suppressing tilting movements of the roller of the inner joint member in the gu

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