Endless belt power transmission systems or components – Means for adjusting belt tension or for shifting belt,... – Tension adjuster has surface in sliding contact with belt
Reexamination Certificate
1999-02-22
2001-04-24
Hannon, Thomas R. (Department: 3682)
Endless belt power transmission systems or components
Means for adjusting belt tension or for shifting belt,...
Tension adjuster has surface in sliding contact with belt
C474S140000, C474S212000
Reexamination Certificate
active
06220981
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a chain link plate, and more particularly to a link plate for a power transmission chain driven for running while a side edge of the link plate is kept in sliding contact with a shoe surface a chain guide and the like.
2. Description of the Related Art
Conventional power transmission chains generally include a link plate A
1
having rectilinear side edges A
2
, as shown in FIG.
6
(
a
), or a link plate B
1
having curvilinear side edges B
2
concaved at longitudinal central portions thereof, as shown in FIG.
6
(
b
).
In a conventional power transmission chain C shown in FIG.
7
(
a
), the link plate A
1
having a contour shown in FIG.
6
(
a
) is used as both inner and outer plates of the power transmission chain C. The power transmission chain C is trained around a drive sprocket S
1
and a driven sprocket S
2
for transmitting rotation of the drive sprocket S
1
to the driven sprocket S
2
.
A chain guide X is disposed exteriorly of a loop of the power transmission chain on a tension run side of the power transmission chain C. The chain guide X has a shoe surface G designed for sliding contact with a side edge A
2
of each link plates A
1
to prevent the tension run of the power transmission chain C from swinging or whipping while the chain C is running.
Similarly, a tensioner Y disposed exteriorly of the chain loop on a slack run side of the power transmission chain C has a tensioner lever R pivotally connected at one end by a pivot pin J, and a tensioner body H urging the other end (distal end) of the tensioner lever R from the back in a direction to force a shoe surface G′ of tensioner lever R against the side edges A
2
of the link plates A
1
. The tensioner Y thus constructed operates to remove a sag of the power transmission chain C so that the slack run of the power transmission chain C is prevented from whipping while the chain C is running.
In the conventional power transmission chain C, when the rectilinear side edge A
2
of each link plate A
1
is in sliding contact with the shoe surface G′ curving outward, as shown in FIG.
7
(
b
), the side edge A
2
and the shoe surface G′ are contacting at one point P. Since the contact point P changes unstably on the side edge A
2
as the chain C moves, the contact pressure between the side edge A
2
and the shoe surface G′ becomes high and thus makes it difficult to form a lubricating oil film between the side edge A
2
and the shoe surface G′. Even when a lubricating oil film is formed between the side edge A
2
of the link plate A
1
and the shoe surface G′, such lubricating oil film is likely to be broken or ruptured. Thus, the power transmission chain C while running is subjected to a relatively large running resistance due to break of the lubricating oil film.
When the side edge A
2
of the plate A
1
is in sliding contact with a flat shoe surface G of the chain guide X, as shown in FIG.
7
(
c
), the side edge A
2
, due to its rectilinear configuration, engages with the flat shoe surface G over the entire area thereof. This engagement makes it difficult to keep a lubricating oil film between the side edge A
2
and the shoe surface G. Additionally, due to a large contact area between the side edge A
2
and the shoe surface G, the power transmission chain C while running encounters a large running resistance.
In the case of a power transmission chain having link plates B
1
narrowed at longitudinal central portions, as shown in FIG.
6
(
b
), the curvilinear side edge B
2
of each link plate B
1
comes into sliding contact with the flat shoe surface G at two portions located near opposite longitudinal ends of the side edge B
2
, as shown in FIG.
8
. The link plate B
1
having such curvilinear side edge B
2
has a smaller contact area relative to the shoe surface G as compared to the link plate A
1
having the rectilinear side edge A
2
shown in FIG.
6
(
a
). However, due to the narrowed longitudinal central portion of the link plate B
1
, there is a large space S formed between a concaved central portion of the side edge B
2
and the shoe surface G. The large space S cannot retain or hold within it lubricating oil L, tending to cause break of the lubricating oil film at contact points between the side edge B
2
and the shoe surface G.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to overcome the foregoing difficulties associated with the prior art and to provide a link plate for power transmission chains which is capable of collecting and holding a lubricating oil between a side edge of the link plate and a shoe surface of a chain guide member so as to reduce a running resistance of the chain produced due to frictional engagement between the side edge and the shoe surface.
A link plate of the present invention is used in a power transmission chain which is driven to run while a side edge of the plate is in sliding contact with a shoe surface of a chain guide member. The link plate includes a pair of contact portions provided on the side edge adjacent to opposite longitudinal ends thereof for sliding contact with the shoe surface, and a recessed central portion of the side edge extending between the pair of contact portions so as to form together with shoe surface a space which is capable of collecting and holding lubricating oil when the contact portions are in sliding contact with the shoe surface.
As the link plate slides on the shoe surface, the lubricating oil trapped in the space gradually enters between the contact portions and the shoe surface to thereby form an oil film. The oil film lowers friction between the contact portions and the shoe surface and hence reduces running resistance of the power transmission chain.
The recessed central portion may have a flat surface slightly spaced from the shoe surface, a knurled surface having a number of small ridges, or a corrugated surface having alternate ridges and grooves. The ridges have tip ends slightly spaced from the shoe surface. The spacing between said recessed central portion and the shoe surface is preferably not greater than 0.5 mm.
The contact portions of the link plate may be arcuate. In the case where the recessed central portion used in combination with the arcuate contact surfaces is rectilinear, it is preferably to provide a round corner portion extending continuously between each of the arcuate contact portions and an adjacent one of opposite ends of the rectilinear recessed central portion.
The above and other features and advantages of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which preferred structural embodiments incorporating the principles of the invention are shown by way of illustrative examples.
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patent: 3948114 (1976-04-01), Koinzan
patent: 4099424 (1978-07-01), Pemberton
patent: 4328665 (1982-05-01), Taubert et al.
patent: 4411131 (1983-10-01), Ohnishi et al.
patent: 5073153 (1991-12-01), Wu
patent: 5176584 (1993-01-01), Ishida et al.
patent: 5242333 (1993-09-01), Sugimoto et al.
patent: 5797818 (1998-08-01), Young
patent: 5908363 (1999-06-01), Suzuki
patent: 5967926 (1999-10-01), Kozakura et al.
patent: 5984815 (1999-11-01), Baddaria
patent: 2 326 213 (1998-12-01), None
patent: 63-219940A (1988-09-01), None
Armstrong Westerman Hattori McLeland & Naughton LLP
Hannon Thomas R.
Tsubakimoto Chain Co.
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