Note: Descriptions are shown in the official language in which they were submitted.
1152776
BACKGROUND OF THE INVENTION
This invention relates to a power transmission belt
adapted to transmit power from one pulley to another pulley.
The invention is intended to overcome the difficulties inherent
in a so-called "multi-V-belt" adapted to transmit large torques
from a driving pulley to a driven pulley. The problems include
vibration and turn-over thereof, which are often caused during
the run. This invention also eliminates power transmission loss
due to the non-uniformity in length of the belt elements forming
the multi-V-belt, and increases the service life thereof~
In a conventional multi-V-belt drive system, a plur-
alit~ of belts are laid over pulleys having a plurality of pulley
gxooves in such a manner that the belts engage the pulley grooves,
respectively, Therefore, in the case where the multi-V-belt
system is employed for driving a machine such as a crusher or a
compressor which generates a relatively great impact load, the
belts are liable to he vibrated separately and to be brought into
contact with one another. As a result, the belts may be turned
over~ or come off the pulleys~ and the helts may ~e prematurely
damaged. A V-belt is driven through friction, and therefore it
is necessary to apply a suitable tension to the belt before it is
run. However~ in the conventional multi-V-belt system, the belts
are liable to he non-uniform in tension because as described
ahove~ the lengths of the belts are not uniform and as a resull
the belts are vibrated and the service lives thereof are shorten-
ed.
In order to overcome these difficulties, a power trans-
mission belt has been proposed in the art, which is ohtalned by
connecting the upper surfaces of individual V-belt bodies with a
tie band formed with a wide cross angle fabric. Because the
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~52776
wide cross angle Eabric is used, the belt is high in lengthwise
stretchability, but it is low in widthwise stretchability be-
cause the angle in the widthwise direction is smaller. Accord-
ingly, the belt cannot satisfactorily engage with the pulley,
and the tie band is liable to peel off the belt~ Thus, the pro-
posed belt is still disadvantageous.
A power transmission belt using a nylon cord fabric as
its tie band is also known in the art. This belt has excellent
stretchability in the longitudinal direction. However, when the
belt is used with a small diameter pulley, the rubber interposed
between the cords of the cord fabric is excessively stretched,
and accordingly the rubber is liable to be cracked. Since nylon
cord fabric is used, the stretchability of the helt in the lat-
eral direction is low, and therefore, the belt cannot suita~ly
engage the pulley.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to elimin-
ate all of the above-descrihed difficulties accompanying a con-
ventional power transmission helt.
~O Another object of this invention is to provide a power
transmission belt having a tie band stretchable only in the lon~-
itudinal direction to have uniformity of width,
Still another object of this invention is to provide a
power transmission belt that eliminates power transmission loses.
The foregoing and other objects of the invention has
been achieved by the provision of a power transmission belt com-
prising a p]urality of V-belt bodies, and a tie band stretchahle
only in the longltudinal direction, The tie band connects the
upper surfaces of the V-belt hodies, In the power transmission
belt according to the invention, the width of the tie band is
negligibly changed because of the lengthwise stretchability.
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-`~ 115277~;
1 This invention will be described with reference to
the accompanying drawings and the description of the preferred
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 and Fig. 2 are perspective views showing examp-
les of a power transmission ~elt according to this invention;
Fig. 3 is a plan view of one example of a stretchable
fabric arranged in a tie band of the power transmission belt
according to the invention;
1~ Fig. 4 is an explanatory diagram showing the woven
pattern of the stretchable fabric shown in Fig, 3;
Fig, 5 is a plan view of another example of the fabric
used for forming the tie band of the power transmission belt
according to the invention;
Fig. 6 is a plan view showing the fa~ric illustratea
in Fig. 5 which is rearranged to be embedded in the rubber layer
of the tie band;
Fig. 7 illustrates another method of cutting the woven
fabric shown in Fig. 5;
Fig. 8 is a plan view showing the fabric illustrated
in Fig. 7 which is rearranged to ~e em~edded in the ru~ber layer
of the tie band;
Fig. 9 is a perspective view of another example of the
power transmission belt according to the invention in which the
fabric in Fig. 8 is employed;
Fig. 10 is a plan view of another example of the fabric
used in the tie ~and of the power transmission belt according to
the invention; and
Fig. 11 is a side view showing a method of winding the
fabric shown in Fig. lQ around the V-belt bodies of the power
transmission belt according to the invention.
SZ776
1 DESCRIPTION OF THE PREFERRED EMBODIMEN_
Fig. 1 shows one example of a power transmission belt
according to the invention. In Fig, 1, reference numeral 1
designates a tensile member made of a rope of fibers such as
polyester fibers, nylon fibers, rayon fibers or aromatic poly-
amide fibers ("Kevlar"~ high in strength in a V-belt body, A
compression rubber layer 2 and an upper core rubber layer 2' are
also shown. The outer surface of each V-belt body is covered
with a rubbered bias fabric made of cotton yarns. The upper
parts of the V-belt bodies are connected to one another with one
tie band T which is obtained by covering the upper and lower sur-
faces of a stretchable fabric 5 with rubber 4, to form one unit,
The V-belt bodies are ordinary wrapped V-helts, The
tie band T is manufactured in accordance with the following met-
hod in order to improve its stretchability in a longitudinal di-
rection and its rigidity in a lateral direction, Stretchable
crimped nylon yarns subjected to wooly treatment are employed as
warps 5a, and cotton yarns, nylon yarns or polyester yarns high
in rigidity are employed as wefts 5b, to weave the fa~ric 5,
The fabric 5 is embedded in the flexible rubber 4 which is equal
in quality to the rubhers 2 and 2' of the V-belt body.
An ordinary plain weave fabric stretchable only in the
longitudinal direction may be employed; however, in this-invent-
ion a twill weave fabric is primarily employed in order to in-
crease the service life of the belt.
The twill weave fabric 5 is a twill weave pattern in
which the warps 5a and wefts 5b each have at least three yarns
interlaced with one another to show diagonal lines on the surface.
The warps 5a and wefts 5b form wavy cross-points every two yarns.
Therefore, the number of wavy cross-points of the twill weave
*Trade Mark ~4~
~15277~
1 fabric is much smaller than that of the ordinary plain weave
fabric. Accordingly, it is possi~le to sufficiently fill the
spaces between the yarns and the cross~points with the rubber 4.
Therefore, it is possible to prevent the warps 5a and the wefts
5~ from being brought in direct contact with one another when
the belt is bent. This results in an improvement oE the service
life of the belt.
Figs. 3 and 4 are detailed pattern diagrams showing
one example of a fabric used as the tie band of the power trans-
mission belt described above. As shown in these figures, crimpednylon yarns made stretchable through wooly treatment are used as
the warps 5a, and ordinary nylon yarns, cotton yarns or polyester
yarns are employed as the wefts 5b, to weave the fabric having
a twill weave pattern.
The fabric having the twill weave pattern is suitable
as the tie band T of the belt according to the invention, because
it has appropriate strechability. The woven pattern weave fabric
in which the warps and the wefts are alternately interlaced with
one another. That is~ in the woven pattern, as shown in Fig. 4,
~0 a first warp Wl appears over a weft Fl, then disappears under
the next two wefts F2 and F3, and then appears oYer the fourth
weft F4. A second warp W2 next to the warp Wl disappears under
the wefts Fl and then appears over the next weft F2. A third
warp W3 next to the warp W2 disappears under the wefts Fl and F2
andthen appears over the weft F3; and so forth.
If this woven pattern is viewed b~ standing on the side
of the wefts~ the weft Fl disappears under the warp W1 and then
appears over the warps W2 and W3. The wefts F2 appears over the
warp wa, then disa~pears under the warp W2~ and appears over the
warps W3 and W4. The third weft F3 appears over the warps Wl and
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1152776
1 W2 and then disappears under the warps W3; and so forth. Since
the warps and the wefts are interlaced with one another this
way, the positions of the visible warps and wefts move stepwise
upward to the right. As a result a woven pattern having oblique
lines which run upward to the right is defined; that is, a so-
called twill weave is obtained.
With respect to the connection of the tie band T made
of the fabric as shown in Figs. 3 and 4 $o the V-belt bodies, it
i5 unnecessary to arrange the tie band T to have a wide angle,
unlike the conventional tie band, because the warps 5a of the
stretchable fabric 5 forming the tie band T have been treated to
be stretchable. That is, as shown in the cut away section of
Fig, 1, the tie band can be effectively arranged so that the
wefts 5~ of the stretchable fabric 5 form a ~0 angle with the
longitudinal axis of the belt.
The tie band T may be bonded to the V-belt bodies with
an adhesive because the rubber 4 incorporating the stretchable
fa~ric 5 is equal in quality to the rubbers 2 and 2' of the V-
belt bodies. However~ it is advisable that the tie band and the
~-belt bodies be strongly comhined together as one unit in the
process of vulcanization. In addition, it is preferahle that a
U-shaped thin groove 6 be formed between adjacent V-belt bodies
and in the lower surface of the tie band T.
Fig. 2 shows a second embodiment of the power transmiss-
ion belt according to the invention, In this belt, the structure
of its tie band T and the connection of the tie band to its V-
belt bodies are similar to those of the belt shown in Fig. 1.
However~ in the belt shown in Fig. 2, only the lower surface of
each ~ belt hody is covered with a rubbered bias fabric 3, and
3~ the ~oth sides thereof are not cover~d with the fabric so that the
-' 11527'~
1 ru~ber 2 is expos~d~
Hence, the power transmission belt shown in Fig. 2 is
obtained by connecting raw edge type V-belt hodies with the tie
band. In this power transmission belt, the side surfaces of
each V-belt body are not covered with the fabric, ThereEore,
the power transmission belt is advantageous in that the coeffi-
cient of ~riction of the ~elt is higher than that of the wrapped
V-belt shown in Fig. 1, and accordingly the power transmissian
performance is higher.
1~ In the above-descri~ed examples, only one ply of stret-
cha~le fabric 5 is employed for forming the tie band; however,
it should be noted that the invention is not limited thereto or
there~y. That is, two or more plys of stretchable fabric can
be used for forming the tie band depending on requirements of
actual use.
The power transmission belt according to the invention
is formed as described above~ In other words, a plurality of
V-belt bodies are connected together with the tie band obtained
by embedding in the rubber the particular fabric, The fabric
is woven with the stretchable crimped yarns, su~jected to wooly
treatment, as the warps and with the cotton yarns, the nylon yarns
or polyester yarns as the ~fts so that the number of cross-
points is small, in such a manner that the wefts form 90 degrees
with the longitudinal axis of the belt,
Accordingly, when compared with the conventional multi~
V-belt or the conventional ~ower transmission belt Cmulti-rib
beltl obtained by connecting V-belt bodies with a tie band, the
stretchability in the longitudinal direction o~ the power trans-
mission belt according to the invention is considerably high,
With the power transmission belt according to the inYention,
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llS'Z776
1 problems such as vibra-tion, turn-over and removal, which occur
frequently with the conventional power transmission belt can be
effectively prevented, the belt life is increased, and the power
transmission performance is improved.
Also, a power transmission belt is greatly affected by
the conditions in use, especially by heat and water; that is,
sometimes the width of the belt is changed by these factors. As
a result, the belt cannot satisfactorily engage the pulley. How-
ever, this difficulty can be effectively eliminated ~y the power
transmission belt according to the invention, because the wefts
5b are cotton yarns, nylon yarns or polyester yarns high in
rigidity.
Now, the conditions of use of the fabric incorporated
in the tie band T of the power transmission belt according to
the invention will be described
The fabric 5 is, in general, a plain weave fabric or a
twill weave fabric which is obtained by weaving wefts 5a which
are crimped nylon yarns subjected to wooly treatment and warps
5h which are cotton yarns, nylon yarns or polyester yarns. This
~0 is shown in Fig. 5. The fabric 5 thus obtained is cut along the
lines L into several pieces of fabric having the same width W.
The pieces of fabric are connected together at the lines J as
indicated in Fig, 6 so that the wefts 5a of the original plain
weave fabric or twill weave fabric 5 are extended in the long-
itudinal direction of the belt and the warps 5b of the same are
extended in the lateral direction of the belt to form a long fab-
ric~
The long fahric thus formed is incorporated in the belt.
More specifically, the long fabric 5 obtained is embedded in the
connecting rubber 4 of the tie band T in such a manner the crimped
115Z776
1 nylon yarns 5a subjected -to wooly treatment extend in the length-
wise direction of the belt, and the cotton yarns, nylon yarns
or polyester yarns 5b extend in the widthwise direction of the
belt, Accordingly, the stretchability in the longitudinal di-
rection of the ~elt is improved, and the change in the widthwise
direction of the belt can be to a certain extent limited.
The wefts 5~ of the fabric embedded in the rubber 4
must be yarns such as cotton yarns, nylon yarns or polyester
yarns which are low in stretchability but high in rigidity. If
the yarns are excessively stretchable or cannot stretch at all,
the belt cannot satisfactorily engage the pulley, Therefore, in
order to permit the belt to sufficiently engage the pulley, the
yarn must have a suita~le stretchability. In view of this, nylon
yarns most suitable are those stretched relatively greatly by
heat generated during the run of the belt.
In the a~oYe-described case, the plain weave fabric or
twill weave fabric shown in Figs. 5 and 6 is embedded in the
rubber 4 of the tie band T in such a manner that it is right-
angled with the lengthwise direction of the belt, That is, the
warps Sa are exposed on the sides of the tie band T. Therefore,
the warps 5a are liable to be frayed out of the sides of the tie
band~ This difficulty may be overcome by arranging the fabric 5
in such a manner that the direction of the warps is oblique with
respect to the belt.
Fig. 9 shows a third embodiment of the power transmiss-
ion belt according to the invention, in which the fabric 5 is
embedded in the rub~er 4 in such a manner that the warps extend
obliquely with respect to the belt. Accordingly, all of the
components of the po~er transmission belt shown in Fig. 9 are the
same as those of the helt shown in Fig. 1, except for the fabric
5.
115277~
1 Figs. 7 and 8 are plan views showning the fabric and
the conditions in use of the fabric. The fabric 5 shown in Fig.
7 is a plain weave fabric obtained by weaving wefts 5a which are
crimped nylon yarns and warps 5b which are cotton yarns, nylon
yarns or polyester yarns, similarly as in the case of Fig. 5.
The fabric is cut along the lines L ~inclined by an angle ~) into
several pieces of fabric having the same width.
These pieces of fabric are connected together at the
lines J as shown in Fig. 8 in such a manner that the wefts 5a of
the fabric 5 are inclined by the angle ~, to form a long fabric.
The long fabric thus formed is embedded in the rubber layer 4 of
the tie band T adapted to connect the V~belt bodies as shown in
Fig, 9. In this case, the warps 5a (which were the wefts of the
original fabric) made of the stretchable nylon yarns subjected to
wooly treatment form the angle 0 with the lengthwise direction of
the belt.
The angle a is, in general, in a range of fr~ 0 to 40
degrees. If the angle ~ is larger than 40 degrees, then the di-
rection of the stretchable warps 5a approaches the widthwise di-
rection of the belt. As a result~ the stretchability in the leng-
thwise direction of the belt is decreased, ana the width of the
belt is greatly changeable, thus ma~ing engagement of the belt
with the pulley unsatisfactory. Therefore, it is most suitable
that the angle ~ be in the range of 0 to 40 degrees. In this case,
it is possible to positively prevent the warps 5a from being
frayed out of the tie band.
~ he plain weave fabric and the twill weave fabric shown
in Figs. 6 and 8 are obtained by cutting the original fabrics
laterally and obliquely into several pieces of fabric and rejoin-
ing these pieces of fabric together, respectively. Therefore,
S2776
1 the joint parts J are thicker than the other parts, Accordinyly,if this lon~ fabric is embedded in the rubber ~ of the tie band
T, then the thickness of the tie band T becomes non~uniform,
which may vibrate the ~elt~
This difficulty can be eliminated by using a plain
weave fabric or a twill weave fa~ric which is o~tained by weav-
ing warps 5a which are crimped nylon yarns subjected to wooly
treatment and ~efts 5~ which are cotton yarns, nylon yarns or
polyester yarns as shown in Fig. lQ. In this case of this plain
weave fabric or twill weave fabric, unlike the fabric shown in
Fig. 6 and 8, it is unnecessary to cut the fabric into several
pieces of fabric and to join them together. That is, the fa~ric
5 can ~e used as is.
When only a single ply of fabric 5 is embedded in the
rubber 4 of the tie band, no joint part is created with the fab-
ric. If, in the case where at least two plys of fabric 5 are
ém~edded in the rubber 4, the fa~ric 5 with a thin rubber layer
4 bonded thereto is wound spirally around the upper surfaces of
a plurality of V-belt bodies 2", then unlike the cases of Figs.
6 and 8, no joint part is created with the spirally wound fabric,
Therefore~ if the fa~ric is spirally wound in succession in this
manner, thèn a belt having a uniform thickness can be o~tained.
As is apparent from the a~ove description, the power
transmission belt according to the invention is obtained by con-
necting the upper surfaces of a plurality of ~-belt ~odies by
using the tie band in which the fabric stretchable in the long-
itudinal direction and rigid in the lateral direction is em~edded.
The resulting power transmission ~elt has the following merits:
~ Since the plain weave fabric or twill weave fabric
with crimped nylon yarns subjected to wooly treatment for the
~152776
1 warps is used for the tie band, the stretchability of the belt
according to the invention is excellent when compared with that
of the conventional multi-V-belt or the conventional power trans-
mission belt obtained by connecting V-belt bodies with a tie
band. It is possible to prevent the belt from vibrating, turn-
ing over, and coming off the pulley In addition, the service
life and the power transmission performance of the belt can be
increased.
(2) Since the plain weave fabric or twill weave fab-
rice obtained by weaving warps ~hich are crimped nylon yarnssubjected to wooly treatment and wefts which are cotton yarns,
nylon yarns or polyester yarns high in rigidity and low in
stretchability is arranged in the tie band in such a manner that
the stretchable warps extend in the lengthwise direction of the
belt, the flexibility of the belt is increased in the longitud-
inal direction of the belt. The width of the ~elt is not signif-
icantly changed under undesirable conditions such as the presence
of heat or water~ and therefore the belt can be satisfactorily
engaged with the pulley at all times.
~3) Since the fabric is embedded in the rubber layer
of the tie band in such a manner that the warps form a to 40
degrees with the axial direction of the belt, it is possible to
preYent the warps from being frayed out of the belt.
C4~ The plain weave fabric or twill weave fabric obtain-
ed ~y weaving w.arps which are crimped nylon yarns subjected to
wooly treatment and wefts which are cotton yarns, nylon yarns or
polyester yarns is used, as it is, for the tie band~ Therefore,
the fabric has no joint parts~ and accordingly the tie band is
uniform in thickness~ Thus, the vi~ration of the belt can be
positiYely prevented.
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