Note: Descriptions are shown in the official language in which they were submitted.
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UNIVERSAL SEAT BELT ~EBBING CONSTRUCTION
BACKGROUND A~D SUM~ARY OE TEE INV~WTION
Seat belt (also called safety belt) systems
have evolved significantly as these systems have
become standard e~uipment in all different types of
cars and other vehicles, and as dif~erent designs of
seat belts have been provided for both active and
passive systems. It has been recognized that in
order to provide an effective and comfortable seat
]o belt system, it is very desirable that the seat belt
webbing itself have a number of desired
characteristics.
Desirable seat belt webbing typically should
have good lateral stiffness and good resilience
across the width of the webbing in order to avoid
"roping" conditions, or folding of the webbing, that
could result in malfunctioning of the seat belt
system. Comfort to the user of the seat belt is
enhanced by the use of a soft edge, yet the webbing
must still have good abrasion resistance. Further,
it is necessary that the webbing be relatively thin,
and have low longitudinal stiffness, in order to
provide good winding and lock-up characteristics.
According to the present invention, a woven
seat belt webbing is provided which has all of the
desirable characteristics set forth above. The good
lateral stiffness and resilience across the width of
the webbing is achieved by providing both
monofilament and multifilament filling yarns. The
monofilament yarn is a very rigid yarn and provides
excellent fold resistance and good resiliency.
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However it is important that it not protrude at the
edges of the webbing. This is accomplished
according ko the invention by moving the
monofilament and multifilament yarns together as one
across the full width of the shed with a pick needle
while applying a higher ten~ion to the monofilament
yarn than the multifilament yarn.
Comfort to the user is achieved according to
the present invention by providing a soft and round
edge appearance. A soft and round edge appearance
is provided in part by controlling the filling
tension of the monofilament yarn, as described
above; and by providing a particular catchcord
formation along one edge of the webbing. This is
also accomplished by providing a smaller warp yarn
in the selvedge portions of the webbing and a
second, larger, warp yarn in the central portions of
the webbing, the first warp yarn having smaller
dimensional properties than the second yarn so that
a round and soft edge appearance is provided.
Typically, single ply warp yarns are provided in the
selvedge portions and double ply warp yarns of the
~ame nominal denier or detex in the central
portion. This also allows the production of a
narrower and thinner webbing with soft edges for a
given tensile strength, which is very desirable.
Low longitudinal stiffness, which when combined
with the thinner webbing offers good winding and
lock-up Gharacteristics, is also provided by the use
of the smooth monofilament filling yarn. With the
thinner webbing, web storage is also substantially
increased.
Despite the round and soft edge appearance,
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seat belt webbing according to the invention also
has good abrasion resistance. Again, the
monofilament/multifilament construction provides
good abrasion resistance in part as a result of the
improved lateral stiffness provided thereby which
results in a product with good stability. Utilizing
the webbing according to the invention, less edge
filamentation, less rippling, and less curvature
after many cycles of use, can be expected.
The method ~f making seat belt webbing
according to the invention preferably utilizes a
needle loom. The method comprises the following
steps: (a) Providing warp yarn~ in a shed. ~b~
Weaving filling yarns with the warp yarns~ the
filling yarns comprisiny a monofilament yarn and a
multifilament yarn, by moving the monofilament and
multifilament yarns together as one across the full
width of the shed with the pick needle, and by
applying a different tension to the monofilament
yarn than the multifilament yarn so that the
monofilament yarn does not protrude on the edges of
the webbing. And, (c) providing stitching along one
edge of the webbing to hold the filling yarns in
place along that edge. Step (a) is practiced by
providing different warps for the ~elvedge portions
than the central portion in the shed so that the
webbing has a soft and round appearance. This is
preferably accompli6hed by providin~ single ply warp
yarns in the selvedge portions and double ply warp
yarns, with each ply of the same nominal denier and
detex as the selvedge yarns, in the central
portions. Also, steps (b) and (c) are preferably
practiced by knitting two catchcord yarns at the
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edge portion, using a binder thread and a locking
thread as the two catchcord yarns, and by
controlling the tension of the locking yarn to
assure an even edge and a cushion over the filling
yarns, and controlling the tension of the binder
yarn to allow the filling yarn to pull itself and
the binder yarn from the edge of the webbing.
It is the primary object of the present
invention to provide a single layer woven belt with
good lateral stiffness and good resilience across
its width, low longitudinal stiffness, good abrasion
resistance, and a soft round edge appearance, and a
method of construction thereof. This and other
objects of the invention will become clear from an
inspection of the detailed description of the
invention and from the appended claims.
BRIEF D~SCRIPTI~N OF T~E DR~WINGS
.
FIGURE l is a schematic illustration of a top
view o an exemplary webbing according to the
invention, while being made;
FIGURE 2 is a detail top schematic view of the
lefthand edge of the webbing of FIGURE l showing the
manner of construction thereof, while being made; and
EIGURE 3 is a top perspective view of a seat
belt made with the webbing accordinq to the
invention.
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DETAIL~D DESCRIPTION OF T~E DRAWINGS
FIGURE 1 schematically illustratas generally by
reference numeral 10 safety belt webbing according
to the invention. The major components of the
webbing include the warp yarns, which are preferably
of two different type~ 11, 12, and the filling
yarns, which also are preferably of two different
types, 13, 14. The webbing 10 is woven on a
conventional loom, which includes a pick needle 15.
The warp yarns 11 preferably are single ply
yarns of a given denier or detax. The denier or
detex will be selected depending upon the particular
fibers of the yarn (e.g. polyester, nylon, or the
like), and the particular end use requirements. The
warp yarns 11 are provided in the selvedge
(marginal, edge) portions of the webbing 10, while
in the central portion the warp yarns 12 are
provided. The warp yarns 12 have greater
dimensional properties than the warp yarns 11, the
warp yarns 11 having small enough dimensions so that
a round and soft edge appearance is provided,
providing good comfort to the user utilizing the
webhing 10. Preferably, the warp yarns 12 are
double ply warp yarns with each ply having the same
nominal denier or detex as the yarns 11. The exact
width of the central portion of the web~ing 10 (that
is that portion comprising the yarns 12 of greater
dimensions) depends upon the particular end use, but
typically the central portion would be -- by a
significant amount -- the majority of tha webbing
10 .
The filling yarn 13 comprises a multifilament
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yarn that iæ perpendicular to the warp yarns 11, 12,
and a monofilament yarn 14. The monofilament and
multifilament yarns 14, 13, are woven parallel to
each other across the full width of the loom shed
(the webbing lO) preferably utilizing a single
~illing arm needle (pick needle) 15. The pick
needle 15 carries the yarns 13, 14 together and
sim~lltaneously back and forth across the width of
the webbing lO during weaving. However, in order to
provide soft edges to the webbing lO a higher
tension is exerted on the monofilament yarn 14 than
on the multifilament yarn 13. This higher tension,
which is applied by conventional means, ensures that
the monofilament yarn 14 does not protrude past the
ed~es of the web~ing lO.
AccordiIlg to the present invention it is also
desirable to provide a knitted configuration at an
edge formation, shown yenerally by reerence numeral
16 i.n FIGURE 1, alone the lefthand side of the
webbing lO. This edge configuration is illustrated
more clearly in FIGURE 2. The edge formation 16 can
be significant in providing a smooth, soft round
edge for the belting lO, and for efficient and
effective production of the product. Edge knitting
per se in belting and the like is known from U.S.
patents 4,313,473 and 4,344,463, for example. The
edge knitting according to the invention is
practiced by knitting two catchcord yarns at the
edge portion, a locking yarn 17, and a binder yarn
18, utilizing a single knitting needle 19. The
tension is controlled on the locking yarn to assure
an even edge and a cushion over the filling yarns
13, 14. The tension on the binder yarn 18 is
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separately controlled to allow the filling yarn to
pull itself and the binder yarn 18 from the edge of
the webbing.
~hen producing the webbing lO according to the
invention, the exact materials, deniers or detex, or
the like for the yarnæ, and the exact weave pattern
or the main body of the belting, or knitting
pattern for the edge formation 16, are not
critical. However it is desirable that all
synthetic yarns be utilized, and according to one
aspect of the invention the central portion of the
webbing lO, in which the larger warp elements 12 are
provided, is provided by a normal weave, whereas the
selvedge portions, containing the smaller yarn
elements 11, is woven in a reverse twill weave.
This reverse twill weave, and the closer packing of
the yarns 11 together than is provided for the yarns
12, results in a "round edge" effect with a smooth
surface.
Thus according to the inventlon a method of
making safety belt webbing is provided which
utilizes a needle loom. Warp yarns ll, 1~ are
provided in a shed, and then the filling yarns are
woven with the warp yarns. The filling yarns
comprise a monofilament yarn and a multifilament
yarn, and the weaving is accomplished by moving the
monofilament and multifilament yarns 13, 14 together
as one across the shed full width while applying a
different (greater3 tension to the monofilament yarn
14 than~the multiilament yarn 13 so that the
monofilament yarn 14 does not protrude on the edges
of the webbing lO. One also provides a knitted
configuration at the edge formation l6 of the
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webbing 10 to hold the filling yarns 13 and 14 in
place along that edge. The knitted configuration is
provided by knitting two catchcord yarns 17, 18 at
the edge portion, using a binder yarn on which the
tension i9 controlled to allow the filling yarn to
pull itself and the binder yarn from the edge of the
webbing, and controlling the tension of the locking
yarn to assure an even edge and a cushion over the
filling yarns.
The invention also comprises a method of making
a single layer woven safety belt webbing by weaving
a warp yarn with filling yarns across the width of
the entire shed, and providing a smaller warp yarn
11 in the selvedge portions of the webbing 10 a
larger warp yarn 12 in the central portions of the
webbing 10. The smaller warp yarn 11 has smaller
dimensional properties than the larger yarn 12 so
that a round and soft edge appearance is provided.
This is preferably accomplished by providing single
ply warp yarns 11 in the selvedge portions and
double pl~ warp yarns 12 of the same nominal denier
or detex in the central portion.
Utilizing the webbing 10 according to the
invention it is possible to produce a seat belt 20
~see FIGURE 3). The seat belt 20 comprises a belt
or strap portion 21 comprised of the webbing 10
according to the invention which passes through an
opening 22 in the metal locking element 23, and
doubled over and stitched to itself at 24 so that it
is permanently fastened to the element 23.
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One exemplary webbing according to the
invention is constructed as follows:
The selvedqe warp yarns 11 are single ply
polyester yarns having a detex of about 940. The
central portion warp yarns 12 are double ply yarns,
comprisiny two yarns each identical to one of the
yarns 11. The multifilament yarn 13 comprises a
polyester yarn having a detex of about 470, while
the monofilament yarn 14 comprises a polyester yarn
having a detex of about 440. The locking yarn 17
comprises a polyester yarn having a detex of about
167, while the binder yarn 18 comprises a polyester
yarn having a detex o about 245.
The selvedge portions (containing the single
ply yarns 11) are woven with a reverse twill weave
to the central portion of the webbing ~containing
the warp yarns 12).
The webbing 10 produced in this manner,
utilized in a seat belt 20, has good lateral
stiffness and good resilience across the width of
the webbing 80 that roping or folding does not
typically occur. Also the belt strap portion 21 has
good user comfort since it has a soft, smooth, round
edge. The seat belt 20 bslt strap portion 21 also
has low longitudinal stiffness and is relatively
thin so that it conforms readily to the take-up
reels, will rewind with low force, and allows a high
volume of web storage.
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While the invention has been herein shown and
described in what is presently conceived to be the
most practical and preferred embodiment thereof, it
will be apparent to those of ordinary skill in the
art that many modifications may be made thereof
within the ~cope of the invention, which scope is to
be accorded the broadest interpretation of the
appended claim~ so as to encompass all equi~alent
products and procedures.
