Rotary shafts – gudgeons – housings – and flexible couplings for ro – Coupling accommodates drive between members having... – Tripod coupling
Reexamination Certificate
2001-03-29
2003-04-15
Binda, Greg (Department: 3679)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Coupling accommodates drive between members having...
Tripod coupling
C464S124000, C464S132000
Reexamination Certificate
active
06547667
ABSTRACT:
BACKGROUND OF THE INVENTION
a. Field of Invention
This invention relates to a plunging type tripod type constant velocity universal joint. Generally, a constant velocity universal joint is a kind of constant velocity universal joint joining two shafts, on the driving and driven sides, and capable of transmitting torque at constant velocity even if there is an angle between the two shafts, wherein the plunging type allows relative axial displacement between the two shafts, while the tripod type is such that a tripod member provided with three radially projecting trunnions is connected to one shaft and a hollow cylindrical outer joint member provided with three axially extending track grooves is connected to the other shaft, the trunnions of the tripod member being received in the track grooves of the outer joint member to effect transmission of torque.
b. Prior Art
An example of the plunging type tripod type constant velocity universal joint will be described with reference to FIG.
13
A. It is constructed in such a manner that the inner peripheral surface of an outer joint member
1
is formed with three axial track grooves
2
, and that annular rollers
7
rotatably fitted through a plurality of needle rollers
6
on the cylindrical outer peripheral surfaces of three radially projecting trunnions
5
of a tripod member
4
inserted in the outer joint member
1
are inserted in the track grooves
2
. A pair of roller guide surfaces
3
opposed to each other circumferentially of each track groove
2
are concave surfaces (partial cylindrical surfaces) parallel with the axis of the outer joint member
1
, while the outer peripheral surface of the roller
7
on each of the three trunnions
5
is a convex surface (partial spherical surface) fit to the roller guide surfaces
3
. Each roller
7
is movable axially of the outer joint member
1
along the track groove
2
while engaging the roller guide surfaces
3
of the corresponding track groove
2
and rotating around the axis of the trunnion
5
.
When the joint transmits torque at an operating angle &thgr; as shown in
FIG. 13B
, the relationship is such that the roller
7
and the roller guide surfaces
3
obliquely cross each other as shown in FIG.
13
C. In this case, the roller
7
tends to rollingly travel in the direction of arrow t in
FIG. 13B
, whereas since the roller guide surfaces
3
are partial cylindrical surfaces parallel with the axis of the outer joint member
1
, the roller
7
will move while being restrained by the roller guide surfaces
3
. As a result, sliding friction occurs between the roller guide surfaces
3
and the roller
7
and sliding resistance is produced. Further, this sliding friction produces induced thrust in the axial direction. Such sliding resistance and induced thrust cause vibration and noise in the car body, influencing the noise, vibration, hardness or NVH performance of automobiles, lowering the flexibility of design of suspensions for vehicles.
As for such plunging type tripod type constant velocity universal joint intended to reduce sliding resistance and induced thrust, for example, one having a construction shown in
FIG. 14A
is known. As shown, the outer peripheral surfaces of the trunnions
5
of the tripod member
4
are true spherical surfaces, and the cylindrical inner peripheral surface of a cylindrical ring
8
is slidably fitted on the true spherical surface. The ring
8
and roller
7
constitute a roller assembly relatively rotatable through needle rollers
6
. The needle rollers
6
are arranged in the full complement bearing condition between the cylindrical outer peripheral surface of the ring
8
and the cylindrical inner peripheral surface of the roller
7
and an annular washer
9
prevents the needle rollers
6
from slipping off. The roller
7
is received in the track groove
2
of the outer joint member
1
and is movable axially of the outer joint member
1
while rolling on the roller guide surfaces
3
of the track groove
2
.
The outer peripheral surface of the trunnion
5
is a true spherical surface having a center of curvature on the axis of the trunnion
5
, and the roller assembly (
7
,
8
,
9
) oscillates around the center of curvature. Since the roller assembly is capable of oscillation, when torque is transmitted at an operating angle formed between the outer joint member
1
and the tripod member
4
, the roller
7
is guided by the roller guide surfaces
3
of the outer joint member
1
such that the roller
7
keeps its position parallel with the axis of the outer joint member
1
, and with the position unchanged, it correctly rolls on the roller guide surfaces
3
. Therefore, the sliding friction reduces when torque is transmitted at a operating angle, and the sliding resistance and the occurrence of induced thrust are suppressed.
It is known to use a plunging type tripod type constant velocity universal joint for transmitting torque from an automobile engine to wheels at constant velocity. A plunging type tripod type constant velocity universal joint, which has spherical rollers attached to the trunnions of a tripod member, is used as a full complement type in which needle rollers serving as rolling elements between the outer peripheral surfaces of the trunnions and the inner peripheral surfaces of the spherical rollers have no cage. And when torque is transmitted at an angle, friction between internal parts causes induced thrust during rotation and forceful axial extension and contraction even in the stopped state causes sliding resistance. As NVH phenomena typical of automobiles taking part in such induced thrust and sliding resistance, there is swaying of the car body occurring in connection with the former during traveling and in connection with the latter there is an idling vibration phenomenon in the drive or D range of an automatic transmission or AT car during stoppage.
Concerning NVH problems of automobiles, the key point for solution is to reduce the induced thrust and sliding resistance of the joint. Generally, the induced thrust and sliding resistance of the joint tend to depend on the size of the operating angle. Therefore, when the joint is to be applied to the drive shaft of an automobile, there occurs a problem of design limitation that a greater operating angle cannot be employed. Therefore, in order to increase the flexibility of design of suspensions for automobiles, it has been necessary to reduce and stabilize induced thrust and sliding resistance.
However, in the conventional plunging type tripod type constant velocity universal joint, since the rolling elements are needle rollers of the full complement type, eccentric loads, such as edge load, tend to act on the rolling element surfaces due to the skewing of the rollers during rotation, etc. Further, the state of contact does not stabilize due to internal clearances and accuracy, and edge load occurs even when the spherical rollers are inclined. Further, structurally, relative slide also occurs between the end of the spherical roller, the trunnion and the washer. Such phenomena as skewing, edge load and relative slide are thought to govern the magnitude of the frictional force in the joint interior.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to minimize these frictional forces to further reduce and stabilize induced thrust and sliding resistance.
The invention provides a constant velocity universal joint comprising an outer joint member formed with three track grooves having roller guide surfaces arranged in circumferentially opposed relation to each other, a tripod member having three radially projecting trunnions, rollers inserted in the track grooves, and rings fitted on the trunnions to support the rollers for rotation, the rollers being movable along the roller guide surfaces axially of the outer joint member, wherein the roller is composed of a set of annular roller portions and a plurality of balls are interposed between outer raceway surfaces formed in rows each in the inner periphery of the annular roller portion and two rows of inner
Kura Hisaaki
Kuroda Masayuki
Nagatani Haruo
Sugiyama Tatsuro
Arent Fox Kintner & Plotkin & Kahn, PLLC
Binda Greg
NTN Corporation
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