Endless belt power transmission systems or components – Belt guide has surface in sliding contact with belt
Reexamination Certificate
2000-03-03
2001-11-06
Bonck, Rodney H. (Department: 3681)
Endless belt power transmission systems or components
Belt guide has surface in sliding contact with belt
C474S111000
Reexamination Certificate
active
06312353
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a chain guide held in sliding contact with a chain for guiding the chain and, in particular, to a chain guide being capable of preventing excessive tightening and loosening of the chain during operation.
2. Description of the Related Art
Conventionally, chains have been used for transmitting rotation of a crankshaft of an engine to a camshaft. A typical example of such a chain is shown in
FIG. 6
hereof. The chain
41
is trained around a drive sprocket
43
fixed to the crank-shaft
42
and a driven sprocket
45
fixed to the camshaft
44
. A chain guide
46
is disposed between the drive sprocket
43
and the driven sprocket
45
and held in sliding contact with the chain
41
for preventing swinging of the chain upon running of the latter.
The chain guide
46
includes a shoe held in sliding contact with the chain
41
. The chain guide
46
has one end secured to a mount surface of an engine (not shown) by means of a bolt
47
and an opposite end with an anchoring arm
48
secured to the mount surface of the engine by means of a bolt
50
passing through an oblong hole
49
formed in the anchoring arm
48
.
After the conventional chain guide
46
is attached to the mount surface, it needs to be positionally fixed such that the chain
41
is not over tightened. However, such a position-fixing operation is difficult to achieve even when the oblong hole
49
is marked with a graduation for position adjustment, because the chain guide
46
has no means for preventing excessive tightening of the chain
41
. Practically, to avoid loosening of the chain after assemblage, the chain guide
46
is fixed with the anchoring arm
48
pushed or forced toward the chain
41
to thereby tension the chain. This often results in fixing of the chain guide
46
with the chain
41
over tightened. The thus-over-tightened chain
41
poses a problem that it produces a whistling sound when driven. To avoid such over tightening of the chain, one may fix the anchoring arm
48
at a retracted position along the graduation. However, this will lead to another problem that unless the anchoring arm
48
is retracted a precisely appropriate amount, the chain becomes loose and hence produces flapping noises.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a chain guide which can be positionally fixed with a simple operation so that excessive tightening and loosening of the chain are prevented.
According to the present invention, there is provided a chain guide comprising: an elongated chain guide body adapted to be held in sliding contact with a chain for guiding the chain, the chain guide body being pivotally mounted at one end to a fixed support member by means of a support axle and having an aperture formed in an opposite end of the chain guide body; and a collar loosely fitted in the aperture in such a manner that a clearance is defined between a peripheral wall of the aperture and the collar at least on that side of the collar which is aligned with a direction of pivotal movement of the chain guide body about the support axle. The collar is firmly secured to the fixed support member so that the chain guide body is allowed to pivot about the support axle in the direction within the range of the clearance.
With this construction, the loose-fit connection between the collar and the chain guide body enables the collar to be secured to the fixed support member with the chain guide body being pressed or forced toward the chain. When the pressure or force on the chain guide body is released, a tension stored in the chain causes the chain guide body to turn or pivot backward away from the chain is forcibly turned or pivoted backward within the range of the clearance. Thus, over-tightening of the chain can be avoided. Preferably, a maximum extent of the clearance is so set as to prevent excessive loosening of the chain which may often result in generation of flapping noises.
The collar may be made of an elastic material in which instance the elastic collar is elastically deformable to increase the range of pivotal movement of the chain guide body by an amount equal to the amount of elastic deformation of the elastic collar. The elastic collar is able to absorb an impact or shock force applied from the chain to the chain guide body.
The collar preferably has an oblong hole formed therein with its major axis substantially aligned with the direction of pivotal movement of the chain guide body. With the oblong hole thus provided, the position of the collar relative to the chain can be adjusted.
In one preferred form of the invention, the collar has a cylindrical shape and the aperture has a generally circular shape with diametrically opposite segmental portions removed. The aperture has a maximum diameter larger than an outside diameter of the cylindrical collar by a distance equal to the amount of the clearance. The peripheral wall of the aperture includes a pair of diametrically opposed flat surfaces forming the removed segmental portions of the generally circular aperture. The flat surfaces are substantially parallel to the direction of movement of the chain guide body and slidably engageable with an outer peripheral surface of the collar for guiding pivotal movement of the chain guide body.
REFERENCES:
patent: 4832664 (1989-05-01), Groger et al.
patent: 5647812 (1997-07-01), McDonald et al.
patent: 5665019 (1997-09-01), Sheffer et al.
patent: 5989138 (1999-11-01), Capucci
patent: 35 25 746 (1987-01-01), None
Bonck Rodney H.
Dann Dorfman Herrell and Skillman, P.C.
Skillman Henry H.
Tsubakimoto Chain Co.
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