Endless belt power transmission systems or components – Friction drive belt – Including particular means connecting opposite ends to form...
Reexamination Certificate
1999-04-26
2001-05-29
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Friction drive belt
Including particular means connecting opposite ends to form...
C474S258000, C474S260000, C474S268000
Reexamination Certificate
active
06238314
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a power transmission belt and method of fabricating the same.
DESCRIPTION OF THE PRIOR ART
As an example of a power transmission belt, Japanese Patent Application Laid-Open Gazette No.8-303528 discloses a V-ribbed belt which includes an adhesion rubber having a tension member embedded therein, a top fabric covering the back face (outer face) of the adhesion rubber, and a rib rubber formed over the inner face of the adhesion rubber and having a plurality of ribs extending in a belt lengthwise direction.
The above-mentioned Gazette further discloses a technique that a plurality of fabric pieces, obtained by cutting a plain weave fabric on the bias, are joined one after another to form a strip in which warp yarns and weft yarns are diagonally oriented with respect to a lengthwise direction of the strip and in mutually opposite directions, the strip is joined at both ends into a cylinder, and the cylinder is set as a material for the top fabric onto a drum for forming the belt. The joint line between the bias cut fabric pieces in the top fabric extends diagonally with respect to the belt lengthwise direction, while the joint line between both the ends of the strip extends in a belt widthwise direction. The joint lines of these two types both have a butt joint structure in which the ends of the fabric pieces or the ends of the strip are butt seamed.
Further, until the butt joint structure as above-mentioned was employed for the top fabric, there had been employed a lap joint structure that the ends of the bias cut fabric pieces are joined in overlapping relation with each other and both the ends of the strip are also joined in overlapping relation with each other.
However, the butt joint structure has the following problems.
In
FIG. 4
, a reference numeral
11
denotes a strip obtained by joining bias cut fabric pieces
12
one after another, and a reference numeral
13
denotes a diagonal joint line of a butt joint structure. If a portion of the strip
11
is cut away along two lines A
1
, A
2
and the resultant cut fabric is butt joined at both ends into a cylinder, a three-forked part develops at the point where a widthwise joint line
16
formed through the formation of the cylinder meets the diagonal joint line
13
as shown in
FIG. 11
in which the cylinder
27
is set onto a drum
15
.
FIG. 12
shows a cylinder
28
formed in the case where a portion of the strip
11
is cut away along two lines B
1
, B
2
in FIG.
4
. In this case, two three-forked parts develop.
However, when the cut fabric is butt seamed at both ends into a cylinder and the resultant cylinder
27
,
28
is set onto the drum
15
, the steps and works of fabricating the belt are complicated. This not only increases the number of steps but also requires facilities for such work. Particularly in a cut fabric one or both of surfaces of which are previously coated with unvulcanized rubber, when the cut fabric is seamed in a cylinder, the unvulcanized rubber-coated surface of the cut fabric may come to the inner surface of the cylinder. In this case, the seaming work becomes difficult due to stickiness of the unvulcanized rubber. In addition, if the stiffness of the cylinder
27
,
28
is small, the work of setting the cylinder onto the drum
15
becomes difficult. In these cases, enhancement in productivity is hindered. Furthermore, the three-forked part is small in strength and detracts from the appearance of the belt.
To cope with these problems, it can be considered to avoid the emergence of a three-forked part by adjusting the cutting positions of the strip
11
so as not to meet the butt joint line
13
. In this case, however, many portions of the strip
11
are not used for top fabrics, resulting in heavy losses. In addition, such adjustment deteriorates productivity.
On the other hand, the lap joint structure has the following problems.
In
FIG. 13
, a reference numeral
31
denotes a strip obtained by lap joining bias cut fabric pieces
12
one after another, and a reference numeral
33
denotes a diagonal joint line in a lap joint structure of the bias cut fabric pieces
12
. If a portion of the strip
31
is cut away along two lines A
1
, A
2
in FIG.
13
and the resultant cut fabric is lap joined at both ends into a cylinder, a three-forked part develops at the point where a widthwise joint line
36
formed through the formation of the cylinder meets the diagonal joint line
33
as shown in
FIG. 14
in which the cylinder
34
is set onto the drum
15
. In the three-forked part, fabric portions of the cylinder meeting together therein are triply overlapped.
FIG. 15
shows a cylinder
37
formed in the case where a portion of the strip
31
is cut away along two lines B
1
, B
2
in FIG.
13
. In this case, a forked part where fabric portions of the cylinder are quadruply overlapped develops.
Such overlapping of the fabric portions in each joint section involves an inconvenience of increasing the entire volume of the belt. Further, the forked part where the fabric portions are overlapped three or four deep results in the emergence of a hard portion locally thickened in the top fabric. At the portion, a bulge develops on the back face of the belt or the position of the tension member is readily displaced slightly inside the belt. This is disadvantageous to uniformity in section of the belt, readily produces vibrations and sounds during the belt run, and exerts a bad influence on the belt life.
SUMMARY OF THE INVENTION
This invention provides for a power transmission belt and method of fabricating the same whereby the above-mentioned problems are solved, and applies a combination of the butt joint structure and the lap joint structure to a cover fabric of a power transmission belt.
Specifically, an aspect of the present invention provides for a power transmission belt the outer periphery or the inner periphery of which is covered with a cover fabric. The power transmission belt is characterized in that the cover fabric is cylindrically formed of a plurality of fabric pieces joined one to another, one of joint sections of the cover fabric has a lap joint structure that adjacent fabric pieces are lap joined at corresponding ends thereof, and the other one or more joint sections of the cover fabric each have a butt joint structure that adjacent fabric pieces are butt seamed at corresponding ends thereof.
With this arrangement, since one of the plurality of joint sections has the lap joint structure, this eliminates the need to previously form the cover fabric into a cylinder before setting it onto a drum for forming the belt, the cover fabric can be set onto the drum in a manner to be wound thereon, and the lap joint structure can be employed for joining both ends of the cover fabric to each other. In addition, since one of the joint sections has the lap joint structure while the other one or more joint sections each have the butt joint structure, this avoids the butt joint sections from meeting each other to develop a three-forked part and avoids portions of the cover fabric from overlapping three or more deep. Accordingly, the power transmission belt of the present invention is advantageous for ensuring the belt strength and reducing vibrations and noises, and can be readily fabricated.
When the cover fabric is a top fabric covering the back face of the belt, the cover fabric may be formed of a plain weave fabric in which warp yarns and weft yarns are diagonally oriented with respect to the belt lengthwise direction and in mutually opposite directions, the cover fabric may include one or more diagonal joint lines extending diagonally with respect to the belt lengthwise direction and one widthwise joint line extending in the belt widthwise direction, the diagonal joint line may have the butt joint structure, and the widthwise joint line may have the lap joint structure.
In the above-mentioned prior art techniques, the coexistence of the diagonal joint line and the butt joint line on a single top fabric leads to the possibility of emergence of the above
Bando Chemical Industries Ltd.
Bucci David A.
Charles Marcus
Cole Thomas W.
Nixon & Peabody LLP
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