Bi-directional clutch

Details Bi-directional clutch Bi-directional clutch

2001-01-29

2002-11-05

Bonck, Rodney H (Department: 3681)

192 clutches and power-stop control

Clutches

Automatic

C192S056100

Reexamination Certificate

active

06474457

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bi-directional clutch.
2. Description of the Related Art
A conventional bi-directional clutch has a structure as shown in
FIG. 7
, which shows a sectional view of the essential portion of the clutch. A bi-directional clutch
51
is constituted so that a gourd-shaped sprag
55
is disposed within a retainer
54
between an outer ring
52
and an inner ring
53
and is biased by a spring plate
56
. When the outer ring
52
rotates in a normal direction indicated by an arrow a in
FIG. 7
, the retainer
54
rotates in a reverse direction relative to the outer ring, so that the sprag
55
is tilted toward the rotational direction of the outer ring
52
. Therefore, an upper surface and a lower surface of the sprag
55
contact with the outer ring
52
and the inner ring
53
, respectively, so as to form a wedge. As a result, the inner ring
53
rotates idle in a direction indicated by an arrow b, which is the same direction as the rotational direction of the outer ring
52
.
On the other hand, the clutch is constituted so that the sprag
55
is tilted to the reverse direction, when the outer ring
52
is rotated in the reverse direction as shown in FIG.
8
. As a result, the inner ring
53
rotates idle in the same direction as that of the outer ring
52
, or the direction indicated by the arrow b. It should be noted that the inner ring
53
may be locked in rotational directions indicated by arrows c in FIG.
7
and FIG.
8
.
In the conventional bi-directional clutch
51
employing the sprag
55
, when the sprag
55
is abruptly tilted by the application of an excessive torque, the height of the sprag
55
may be abruptly reduced, so that a roll-over (an excessive tilting) phenomenon occurs. As a result, when an excessive torque is loaded, a problem may be caused that the rotational force of the outer ring
52
cannot be properly transmitted to the inner ring
53
, or that the transmission of rotation between the outer ring
52
and the inner ring
53
cannot be properly interrupted.
SUMMARY OF THE INVENTION
The present invention has been contemplated in consideration of the above problems.
It is an object of the present invention to provide a bi-directional clutch, which does not cause a roll-over phenomenon.
According to the present invention, a bi-directional clutch comprises an outer ring, an inner ring and a roller. The roller is retained by a retainer and is positioned between the outer ring and the inner ring. The outer ring has a cam surface, so that the roller forms a wedge that contacts the outer ring and the inner ring. Therefore, the inner ring can be rotated in the same direction as the outer ring. The roller does not cause a roll-over phenomenon that may be caused by the conventional clutch incorporating sprags. Therefore, the rotational force of the outer ring can be properly transmitted to the inner ring, or the transmission of power between the outer ring and the inner ring can be properly interrupted.
Preferably, the cam surface includes a first cam surface for a normal rotation and a second surface for a reverse rotation. Therefore, when the outer ring rotates in either the normal direction or the reverse direction, the roller can form a wedge so as to rotate the inner ring in the same direction as the outer ring.
Preferably, the bi-directional clutch further includes a stopper surface at one end of the cam surface. The roller contacts the stopper surface when a load torque exceeds a set load torque, so that the stopper surface functions as a torque limiter. Therefore, when a large load is applied, the roller contacts the stopper surface, so that a strut angle increases to cause a slip. As a result, an excessive load can be favorably prevented.


REFERENCES:
patent: 3476226 (1969-11-01), Massey
patent: 5672110 (1997-09-01), Kurita et al.
patent: 1-229122 (1989-09-01), None
patent: 9-222136 (1997-08-01), None
patent: 9-222137 (1997-08-01), None

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