Endless belt power transmission systems or components – Positive drive belt – Belt formed of rigid links
Reexamination Certificate
2000-12-27
2002-09-17
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Positive drive belt
Belt formed of rigid links
C474S217000
Reexamination Certificate
active
06450911
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a silent chain including a number of link plates articulately connected together by joint pins and each having a pair of teeth for meshing engagement with sprocket teeth and a pair of pin holes in which the joint pins are inserted.
In general, a silent chain includes articular link rows and guide link rows alternately arranged in the longitudinal direction of the chain and articulately connected by joint pins, such as round pins or rocker joint pins, in such a manner that link plates in each articular link row and link plates in the adjacent guide link row are interleaved in single-to-single, double-to-double, or single-to-double ply bases.
As shown in
FIGS. 4 and 5
, a conventional silent chain
20
generally comprises link plates
21
and
22
and guide plates
23
(see, Japanese Patent Laid-open Publication No. HEI-11-182635). The plates
21
form articulate link rows KL and, as shown in
FIG. 6
, the articulate link plate
21
has a hollow cylindrical bushing
26
formed separately from the plate
21
and fitted in each of a pair of engagement holes
25
formed in the plate
21
. A joint pin
28
(
FIGS. 4 and 5
) is inserted into the bushing
26
so that the articulate link plate
21
is rotatable about the axis of the joint pin
28
. The plates
22
and the guide plates
23
together form guide link rows GL. The guide link plate
22
has a pair of pin holes (not shown) into which the joint pin
28
is inserted. The guide link plate
22
may be or may not be rotatable about the axis of the joint pin
28
. In addition, the guide link plate
22
may or may not have a pair of teeth for meshing engagement with the teeth of a sprocket.
Since the plate
21
is equipped with a bushing
26
fitted in the engagement hole
25
, the contact area for sliding engagement between the inside surface of the pin hole
24
and the outside surface of the joint pin
28
is relatively large and hence can suppress wear on the joint pin
28
. However, as compared to a bushingless plate
31
such as shown in
FIG. 7
, a web width W
1
′ between the outside flank
27
A of each tooth
27
and the peripheral edge
25
′ of the adjacent engagement hole
25
and a web width W
2
′ between the inside flank
27
B of the same tooth
27
and the peripheral edge
25
′ of the adjacent engagement hole
25
are made relatively small provided that the diameter of the pin hole
24
is the same as that of pin holes
32
. There arises a problem that the plate
21
cannot maintain the necessary rigidity and strength. Thus, when subjected to a load during meshing engagement between the teeth
27
and the sprocket teeth, the plate
21
is liable to yield or deform due to insufficient rigidity and strength, thus making the meshing engagement unstable.
Most silent chains are formed solely by bushingless plates
31
, namely, plates not quipped with a bushing. As shown in
FIG. 7
, the bushingless plate
31
can provide a relatively large web width W
1
, W
2
between the peripheral edge
32
′ of each pin hole
32
and the outer or inner flank
33
A or
33
B of the adjacent tooth
33
. Accordingly, even if the thickness of the plate
21
is reduced, the plate
21
is still able to maintain the necessary rigidity and strength. However, since the contact area for sliding movement between the inside surface of the pin hole
32
and the outside surface of the joint pin
28
decreases with the reduction in thickness of the plate
21
, wear elongation of the silent chain is caused due to accelerated wear on the joint pin
28
. To deal with this problem, the thickness t′ of the plate
31
is increased to enlarge the contact area between the pin hole
32
and the joint pin
28
, as shown in FIG.
8
. However, the plate
31
becomes heavy and the overall weight of the silent chain is increased.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a silent chain which is capable of providing a relatively large contact area between pin holes in the link plates and joint pins without narrowing the web width between each pin hole and the outside or inside flank of the adjacent tooth of the link plate, thereby to suppress wear on the joint pins, prevent reduction in strength of the link plate, and limit the increase in the overall weight of the silent chain.
To achieve the foregoing object, a silent chain according to the present invention comprises a number of interleaved rows of link plates articulately connected together by joint pins. Each of the link plates has a pair of teeth and a pair of pin holes. The link plate has a tubular portion protruding continuously from one surface of the link plate and defining a peripheral surface of each of the pin holes. The tubular portion has a height substantially equal to the thickness of the link plate.
In each row of link plates, two link plates may arranged side by side with the respective tubular portions oriented in the same direction.
Alternatively, in each row of link plates, two link plates may be arranged side by side with the respective tubular portions oriented in the opposite directions. The tubular portions of one of the link plates and the tubular portions of the other link plate may be directed toward each other or directed away from each other.
The tubular projection is preferably formed by burring.
By virtue of the tubular portion, the link plate can retain a relatively large contact area between itself and joint pins and hence is able to suppress wear on the joint pins. In addition, the web width between each pin hole and the outside flank or the inside flank of the corresponding tooth is enlarged with the result that the link plate is highly resistant to deformation or yielding when it comes into meshing engagement with the sprocket teeth.
The above and other objects, features and advantages of the present invention will become manifest to those versed in the art upon making reference to the following description and accompanying sheets of drawings, in which certain preferred structural embodiments incorporating the principle of the invention are shown by way of illustrative example.
REFERENCES:
patent: 690317 (1901-12-01), Renold
patent: 958676 (1910-05-01), Dodge
patent: 958677 (1910-05-01), Dodge
patent: 999156 (1911-07-01), Dodge
patent: 1586857 (1926-06-01), Stiansen
patent: 1598906 (1926-09-01), Dull
patent: 2246810 (1941-06-01), Nicolai
patent: 4058021 (1977-11-01), Wood
patent: 5941113 (1999-08-01), Kanemitsu et al.
patent: 11-182635 (1999-07-01), None
Bucci David A.
Charles Marcus
Howson & Howson
Tsubakimoto Chain Co.
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