Note: Descriptions are shown in the official language in which they were submitted.
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V-BELT FOR HIGH LOAD POWER TRANSMISSION
Technical Field
This invention relates to power transmission
belts and in particular to V-belts intended for
high power transmission service.
Back~round Art
In one common form of V-belt for use in
transmitting power as between pulleys, a plurality
of longitudinally extending tensile cords are em-
bedded in a layer of cushion rubber. An outer
tension section of rubber is provided outwardly
of the cushion rubber and an inner compression
section of rubber is provided înwardly of the
cushion rubber~
It is further conventional to cover the belt
with a fabric, such as canvas. The canvas may
completely encircle the belt, or may be applied
only to ~he inner surface and outer surface there-
of, with the sides of the belt defining raw edges.
A serious problem arises in the use of suchconventional belts where hi8h loads are transmit-
ted.' The stresses developed in the belt us a re-
sult of the high load trflnsmission causes cracking
to occur. Both longitudinal crccks and side
cracks have been found to extend through the
cushion rubber in which the tensile cords sre em-
bedded. Such cracks propagate to and into both
the tension ~nd compression sections of the belt,
thereby substantially reducing the useful life of
the belt.
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One attempted 601ution to thiq problem has
been to provide 8 distribution of short reinforc-
ing fibers extending tr~nsve~sely scro~s the belt
in either or both of the compression and ten~lon
sections. Conventionally, approximately 5 to 10
parts by weight of such fibers sre provlted in
such sections. While 6uch a distribution of
reinforcing fibers does incre~se the rigidity in
the transverse directlon, the use of such fibers
has been found to cause the belt to be harder
than desired. Bec2use of the increase in the
hardness, the pre~ention of cracks by such means
is not completely satis~actory.
The inventor~ hereof have proposed previous-
ly, as disclosed in laid open Japanese Utility Model Appli-
cation No. 60144/1979, the provision of a small
amount of such short fibers, such as 0.1 to 3.0
parts by weight, in the compression rubber ~ec-
tion, ~s illustr~ted herein. It has been.
found that such construction dQes provide an im-
proved long life by affording a limited de8ree of
desired rigldity in the compression section.
Such structure h~s been found, howeve~, to be n~t
completely sati~factory in extendi~ng the useful
l~fe of such belts bec~use of the ~hifting of the
ten~ile cords 80 th~t the ~pAcing therebetween
became irregular and ~ome superposition occurred.
A
~Li253360
Disclosure of Invention
_
The present invention comprehends an improved V-belt
structure which overcomes the deficiencles of the prior art
structures in a novel and simple manner and provides
substantially improved long, troublefree life of such a V-
belt, notwithstanding the transmission of high loads
thereby.
The improved V-belt construction of the present
invention provides improved resistance to bending and
cracking and unexpectedly provides improved transverse
stability under severe high load conditions.
The belt construction is extremely simpie and
economical, while yet providing the improved durability and
long life.
More specifically, the invention comprehends the
provision of such a power transmission V-belt wherein the
portion of the belt in which the tensile elements are
embedded is formed of rubber having short reinforcing fibers
distributed therein and oriented longitudinally of the belt.
In one aspect of the invention, the fibers are present
in the ratio of less than 5 parts to 100 parts o~ the
rubber, preEerably approximately 0.1 to 3.0 paxts Eibers to
100 parts rubber.
In another aspect the rubber in which the tensile cords
are embedded i5 caused to have preferably a ShoreA hardness
of approximately 70 to 90.
The tensile cords may be formed of conventional strong
filamentary material. In the illustrated embodiment, the
fibers have a length of approximately 2 mm to 20 mm and may
3G be formed of suitable reinforcing material, such as natural
fiber, artificial fiber, synthetic fiber, and inorganic
fiber materials.
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In the illustrated embodiment, ~he fibess
comprise cut fibers.
A rubberized ~abric cover may be provided on
the inner and outer surfaces and also may be se-
lectively provided on the side edges, as desired.
The fabric cover, in the illustrated embodi-
ment, is made up of bias-laid plies, with the
warps and wefts thereof disposed at a 90 to 140
crossinp angle. The plies are preferably bias-
laid.
In the disclosed embodiments, at least oneof the outermost portion of the tension section
and the innermost portion of the compression sec-
tion is caused to be free of the longitudinally
extending short fibers.
The invention comprehends that the entire
belt body be formed of rubber having short rein-
forcing fibers distributed therein and oriented
longitudinally of the belt, as desired. In all
embodiments of the invention, the portion of the
belt in which the tensile cords are embedded is
provided with the lon~itudinally extending short
fibers.
Brief Description of the Drawin~
,Other features and advantages of the inven
tion will be apparent from the followin~ descrip-
tion taken in connection with the accompanyin~
drawing wherein:
FIGURE 1 is a schematic illustration of A
drive belt embodying the invention, as used in
transmit~in~ power between a driver pulley and a
driven pulley;
FIGURE 2 is a fragmentary perspective view
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of a portion of a belt embodying the invention;
FIGURE 3 is a transverse section illustrating
~a modified form of belt embodying the invention;
FIGURE 4 is a transverse section illustrating
another modified form of belt embodying the inven-
ti~;
FIG~RE 5 is a transverse section illustrating
still another form of belt embodying the inven-
tion;
FIGURE 6 is a transverse section illustrating
a still further belt embodying the invention;
FIGURE 7 is a transverse section illustrating
yet another belt embodying ~he invention;
FIGURE 8 is a transverse section illustrating
a conventional prior art belt; and
FIGURE 9 is a transverse section illustrating
a prior art belt developed by applicants herein.
Best Mode for CarryinR Out the Invention
In the illustrative embodiments of the inven-
tion as disclosed in the drawing, 8 power trans-
mission belt generally designated lO embodying the
invention is illustrated as for use in transmit-
ting high loads between a driver pulley 11 and a
driven pulley 12. As discussed briefly above, the
belt of the present invention is adapted to pro-
vide such high load power transmission with an
extended useful life.
As shown in Figure 2, power transmission belt
lO comprises a V-belt having a plurality of ten-
sile cords 13 extending longitudin~lly of the beltin side-by-side spaced relationship transversely
thereof. The tensile cords are embedded between
an outer tension section 14 and an inner compres-
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sion section 15. In the illustrated embodiment,the tension and compression sections are formed
of similar rubber and are integrally joined be-
tween ~he tensile cords, whereby the belt body
generally designated 16 comprises aD integral uni-
tary construction.
As further illustrated in Figure 2, a distri-
bution of short reinforcing fibers 17 is provided
throughout the belt body. More specifically, the
invention comprehends that ~he longitudinally ex-
tending short reinforcin~ fibers be provided in
the rubber in which the tensile cords are embedded
within the belt body.
Belt 10 is provided with an outer cover fab-
ric 18 which may fully encircle the belt and thuscover the top surface 19 of the tension section,
the bottom surface 20 of the compression section,
and the side edges 21. The belt rubber may com-
prise conventional power transmission belt rubber
which may be blend of a natural rubber, chloro-
prene rubber, and/or styrene butadiene rubber.
The tensile cords are preferably formed of
conventional tensile cord material, such as poly-
ester resin, aliphatic polyamide resin, aromatic
polyamide resin, etc.
The rubber preferably has a Shore A hardness
of 70 ~o 90
The short fibers 17 are preferflbly cut
fibers formed of natural fiber, artificial fiber,
synthetic fiber, inorganic fiber, etc., and in
the illustrated embodiment, have a length of ap-
proximately 2 mm to 20 mm.
The cut fibers are provided in the belt 10
in a ratio of ~pproximately 0.1 to 3.0 parts by
1~533~0
weight of the rubber.
The fabric 18 may comprise a canvas fabric.
The fabric may be formed with one or more plies,
with the warps and wefts of the plies being
formed of cotton yarns, blended yarns of cotton
and nylon yarns, blended yarns of cotton yarns
and polyester yarns, etc. The plies are woven st
a wide crossing angle of approximately 90 to 140
and, in the illustrated embodiment, are laminated
and bonded to the rubber body with rubber in a
bias direction.
It has been found that by utilizing both the
longitudinally oriented short fibers in the rubber
in which the tensile cords are embedded, and pro-
viding the rubber as a relatively hard rubber,
maximum extension of useful life of the belt is
obtained, with minimized cracking snd desirable
bending durability with reduced belt-degrading
heating during use of the drive system.
Referring now to the embodiments of Figures
3-7, the invention comprehends a number of modi-
fications within the broad scope thereof providing
improved long, troublefree life of the belt under
high load conditions.
As seen in Figure 3, a modified form of belt
generally designated 110 embodying the invention
is shown to comprise a belt similar to belt 10 but
wherein the innermost portion 122 of the compres-
sion section 115 is free of the longitudinally
extending cut fibers 117.
Another belt embodying the invention general-
ly designated 210 is shown in Figure 4 to comprise
a belt gener~lly similar to belt 10, but wherein
both the outermost portion 223 of the tension
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section and the innermost portio~ 222 o~ the co~-
pression sectio~ sre provided ~ree of the longi-
tudinally extending cu~ fibers 217.
As further illustrated in Figure 4, the ex-
tent of the cut fiber-free portions of the ten~ion
and compression sections outwsrdly and inwardly of
the portion of the belt in which the tensile cords
are e~bedded uay be selected, ~B desired, within
the broad scope of the invention.
In Figure 5, stiil another form of belt gen-
erally designated 310 embodyin~ the i~vention is
shown to cGmprise a belt similar to belt 10, but
wherein the s~de edges 321. comprise raw ed~es,
with the cover ~sbric 318 being provided only on
the outer surface 319 of the tension section and
the inner surface 320 of the compression section.
Still another form of the inve~tion generally
designated 410 is illustrated in Figure 6 to com-
prise a belt similar to belt 110, but wherein the
side ed~es 421 of the belt comprises r~w edges.
A belt generally design~ted 510 ls illustra-
ted in Figure 7 to comprise a belt generally sim-
ilar to belt 210, but wherein the si~e ed8es 521
thereof comprise raw ed8es~
The unexpected extended useful life .of the
power transmission belts e~bodying the inventlon
is illustrated in the following T~ble 1, whereln
the belt 10 i9 shown to bave a ~ubstsnti~lly in-
creased useful life over the convention and
3~ prior art belts of Figures 8 and 9. As
seen in Figure 9, applicant's prior art structure
referred to previously on page 2 required the
conventional use o a cushion rubber layer
embedding the tensile cords in addition to the
compression section provided with the
longitudinally extending short fibers and the
conventional outer tension section. In
determining the comparison of useful life,
the belts were driven. in a drive system,
as shown in Figure 1, wherein the driver pulley
was 80 mm in diameter, the driven pulley
was 74 mm in diameter, with the driver pulley
A
,.
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being rotsted at 8 speed of 3600 rpm. 6 PS of
load and lO0 kg of initial load were applied.
TABLE 1
Conventic nal belts
Belt 10 Belt A Belt B
(Fig. 2) (Fig.8) (Fig.9)
Running life (Hrs)
Before side487 143 260
cracking
As shown in Table 1, the provision of the
longitudinally extending short fibers in the
portion of the rubber body in which the tensile
cords are embedded provides an unexpectedly sub-
stantial increase in the useful life of the belt.
The provision of the longitudinally extending
short fibers in the portion of the rubber in
which the tensile cords is embedded has been un-
expectedly found to provide desirable transverse
side pressure durability under high loads, while
yet providing desirable bending and crack resis-
tance under such high loads.
By substantially extending the useful life
of the belt before side cracking occurs, loweretl
maintenance Hnd parts costs provide a highly meri-
torious improvement in the power transmission of
high loads in such pulley systems.
The foregoing disclosure of specific embodi-
ments is illustrative of the broad inventive con-
cepts comprehended by the invention.
