Note: Descriptions are shown in the official language in which they were submitted.
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WO 99/40247 PCT/EP 99/00605
Inflatable Belt Strap
The invention relates to a two-ply, inflatable belt webbing, more particularly
for a seat belt.
"Webbing" or "belt webbing", "belt" or "seat belt" as termed in the following
is always
intended to mean substantially the same thing, i.e. always involving materials
or semi-
finished products for use in the manufacture of seat belts, webbing and
modular components
of motor-vehicle, aircraft and marine passenger restraint systems, this
applying in the same
way too, to the terms "tube" or "fabric".
German Patent 20 08 048 teaches a belt webbing in which the belt evident
therefrom is
configured as a tube comprising a stitched-in burst fold configured in such a
way that it
bursts due to the tensile forces exerted by the belt in a crash situation and
the opening of a
valve coupled thereto causes inflation of the tubular belt. As a result of
this the belt located
as a flattened tube prior to the accident and whose width corresponds to half
the
circumference of the inflated belt is abruptly inflated. Due to this it
represents to advantage,
as compared to the simple belt, an impact cushion. However, adequate
protection of the
vehicle passenger is not satisfactorily assured due to the insignificant
extent of the inflated
tubular belt. An increase in the circumference of the belt tube with an
inflatable cushion
arranged in a part of the belt around the belt, likewise stated in the cited
document, is also of
a disadvantage since the corresponding cushion is not necessarily located at
the right position
and thus fails to be available for its actual purpose.
Known from the international patent application publication WO 97/06983 is an
inflatable
tubular restraint system. The seat belt system shown in this case consists of
a lap belt and a
shoulder belt, the lap belt consisting regionally of an inflatable balloon,
the length of which
is shortened during inflation thus having in addition to the cushioning
function also a belt
McCarthy Tetrault LLP TDO-RED #8255447 v. 1
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-la-
AT-B-300 591 shows a safety belt including one or more
inflatable hollow bodies which is characterized by it being
foldable about its longitudinal centerline in the empty
condition. Shown is a belt hollow body which due to its
voluminous fabric is uncomfortably bulky and is totally
unsuitable for convenient handling by the passenger.
DE-OS 37 14088 discloses a belt webbing for a vehicular
restraint system in which an inflatable air hose is applied
to the belt webbing via an intermediate support or a bonded
joint. The belt itself comprises zones extending in the
longitudinal directon of the belt for differing work
handling (differing expansion properties transversely to
the width of the belt) which, on the one hand, serve energy
depletion or work handling in the loaded condition and, on
the other, to achieve localized differing expansion
properties of the belt by careful selection so that the
edges of the belt when loaded are curved inwards to move
away from the person to be protected, as a result of which
the known nipping effect of a belt on the body of the
person to be protected in the loaded condition is
substantially reduced. The arrangement of a belt webbing as
described herein with zones for work handling and means for
enlargening the contact surface area of the belt webbing
(inflatable air hose) is highly complicated and has failed
to find acceptance due to the multiple part arrangement
also because of the high production costs involved.
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tensioning function. In this arrangement, however, although the midriff zone
of the passenger is
particularly protected, the shoulder and head zone - except for an additional
restraint of the
shoulders due to the tensioned belt - fails to be taken into account.
The German disclosure DE 43 05 291 As shows a seat belt incorporating an air
bag, this belt
having the form of two conventional belt webbings consisting of a low-stretch,
pliable material.
Between these two belt webbings are provided folded joining elements at both
outer edges. In
the starting condition the complete arrangement is held together by burst
seams such that it has a
minimum thickness. Although the belt webbigns and joining elements are
intended for an
endless fabrication, they need to bejoined to each other in additional costly
steps in the method,
however.
According to a first broad aspect of the present invention, there is provided
a two-ply inflatable,
one-part belt webbing for a belt, wherein (a) said belt webbing is woven as a
tubular belt
webbing having two woven plies, namely an upper woven ply and a lower woven
ply, (b) wa-p
threads in middle portions of said two woven plies provide a rupture strength
of said webbing to
withstand tensioning forces imparted to said belt webbing, (c) in edge
portions of said belt
webbing adjoining said middle portions, edge portion warp threads therein
handle substantially
zero belt tensile force, said edge portion warp threads and the weft threads
of the belt webbing
being substantially finer than warp threads in said middle portions, (d)
fabric of said edge
portions adjoining said middle portions is folded about outer folding edges
oriented parallel to
the longitudinal direction of said belt webbing so that said fabric comes to
rest in each case
between said middle portions of said upper and lower woven ply, and (e) said
middle portions of
said upper woven ply and of said lower woven ply are releasably joined to each
other in the
portion adjoining said outer folding edges.
According to a second broad aspect of the present invention, there is provided
a two-ply
inflatable, one-part belt webbing for a seat belt, wherein (a) said belt
webbing is woven as a
tubular belt webbing having two woven plies, namely an upper woven ply and a
lower woven
ply, (b) warp threads in middle portions of said two woven plies provide a
rupture strength of
said webbing to withstand tensioning forces imparted to said belt webbing, (c)
in edge portions
of said belt webbing adjoining said middle portions, edge portion warp threads
and the weft
threads of the belt webbing are substantially finer than warp threads in said
middle portions; (d)
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fabric of said edge portions is folded about outer folding edges oriented
parallel to the
longitudinal direction of said belt webbing so that said fabric comes to rest
in each case between
said middle portions of said upper and lower woven ply, and (e) said middle
portions of said
upper woven ply and of said lower woven ply are releasably joined to each
other in the portion
adjoining said outer folding edges.
It is thus the object of the invention to define a belt or belt webbing of the
aforementioned kind
and a method of producing same which ensures optimum passenger impact
protection in a crash
situation more or less without any restriction, i.e. possibly also independent
of any location.
This object is achieved by a two-ply inflatable belt webbing wherein it is
woven as a tubular belt
webbing having two woven plies, namely an upper woven ply and a lower woven
ply, wherein
the total rupture capacity of the warp threads in the middle portions of the
two woven plies of the
belt webbing roughly making for the width of a conventional belt webbing
corresponds to that of
the warp threads of a conventional (seat belt) belt webbing, wherein the warp
threads ofthe edge
portions adjoining the middle portions and the weft threads of the belt
webbing are finer than the
warp threads in the middle portions, wherein the fabric of the edge portions
adjoining the middle
portions is folded about outer folding edges oriented parallel to the
longitudinal direction of the
belt webbing so that the fabric comes to rest in each case between the middle
portions of the
upper and lower woven ply and wherein the middle portions of the upper woven
ply and of the
lower woven ply are releasably joined to each other in the portion adjoining
the outer folding
edges.
Producing the belt webbing as a woven tubular belt webbing produced endless
and having two
woven plies, in which the total rupture capacity of selected warp threads
corresponds to the total
rupture capacity of the warp threads of a conventionally woven belt webbing,
eliminates the
highly cost-intensive joining of endless belt material to endless air bag
material
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by stitching, tacking or welding them together. Producing a belt webbing in
the webbing
weaving loom permits exceptionally cost-effective endless production of the
belt webbing in
accordance with the invention and thus also no problem in cutting to length
for each
particular application. In one advantageous aspect of the woven tubular belt
webbing the warp
and weft thread floats exceed or equal 2, as a result of which when the belt
webbing is
kinked along the edges of the middle portions softer edges and thus softer
belt webbing edges
materialize which enhance the wearing comfort and reduce wear and tear of user
clothing.
The rupture load capacity of both middle portions of the belt webbing in
accordance with the
invention handling the tensile function of belt webbings together corresponds
to the rupture
load capacity of a conventional belt webbing. In the regions juxtaposing the
side edges the
two belt webbings may be joined to each other by means of a burst seam
designed to burst
in a problem situation and permit deployment of the tubular fabric. Instead of
burst seams
other means of joining the fabric plies located fan-folded on each other may
be selected, e.g.
bond tacking or welding. This configuration is especially of advantage since
it features a
hard-wearing material on all outer sides of the belt webbing.
The inflatable fabric which is folded in the resting position is deployed in a
problem situation
bv being abruptly inflated e.g. by conventional inflator means to its maximum
tube size
which may approach the volume of an air bag as known to the person skilled in
the art, thus
offering optimum passenger protection. The tubular fabric is selectable with a
tube diameter
as desired in each case as best suited to sufficiently cushion the pelvis,
hips, chest, shoulders
and head.
The advantages consist mainly in a one-part integral embodiment of the belt
webbing. To
enhance the user friendliness of the belt webbing an edging of a soft material
may be applied
to the side edges of the first and/or second belt webbing to reduce passenger
clothing wear
and tear.
Due to the fact that the belt webbing in accordance with the invention
contains substantially
more material than a conventional belt webbing there is a possibility of a
space problem
materializing in it passing through the buckle tongue or retractor mechanism
of the seat belt
means. An immediate solution to this problem as regards the buckle tongue is
achieved by
widenina the passage slot of the buckle tongue. However, to avoid any increase
in size of the
retractor mechanism in conjunction with belt webbing in accordance with the
invention it can
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be configured as a conventional webbing as of the point at which the coiled
webbing comes
to rest just before the retractor mechanism.
Further advantageous features read from the sub-claims.
Example embodiments of the invention will now be described in further
explaining the
invention and in illustrating how it is configured with respect to the
drawings in which
FIG. I is a greatly simplified schematic illustration in cross-section of one
example
embodiment of a belt webbing in accordance with the invention, shown before
being folded.
FIG. 2 is a slightly magnified view of the belt webbing as shown in FIG. 1 in
the folded
condition after application of the burst seams.
FIG. 3 is a view of the belt webbing as shown in FIG. 2 but shortly after
bursting of the
burst seams on commencement of the inflation phase.
FIG. 4 is a view of the belt webbina as shown in Figs. I to 3. illustrated
interrupted to
save space, in the fully inflated condition.
FIG. 5 illustrates an embodiment similar to that of the previous example
embodiment
whereby in the middle portion of the belt webbing, however, space for a gas
supply conduit is maintained free.
Referring now to FIG. 1 there is illustrated schematically and greatly
simplified in cross-
section a belt webbing 2, prior to be folded, woven as a tubular belt webbing
with two woven
plies, namely an upper woven ply 42 and a lower woven ply 41. All of the
tensile force
involved is handled by "thick" warp threads. for example 1100 dTx tine, in the
middle
portions MB. taking up roughlv the width of a conventional belt webbin~~, of
the two woven
plies 41. 42 of the belt webbing. these threads being indicated symbolically
by the points 43
and 44. It will readily be appreciated that the number of warp threads 43. 44
handling the
overall tensile force in the belt in each woven laver of the belt webbing in
accordance with
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the invention is substantially higher (for example 180 to 200). The warp
threads in the edge
portions RB adjoining the middle portions and the weft threads of the belt
webbing are finer
than the warp threads 43, 44 in the middle portions, 550 dTex, for example,
having proven
to be highly expedient for the thickness of the warp threads in the edge
portions RB and for
the weft threads. The material woven with this dTex proved to be very suitable
for folding in
the interspace between the middle portions MB of the woven plies 41 and 42
(FIG. 2) and
has a proven record of success as air bag fabric. Preferably, warp and weft
run floating in the
middle portions MB , whereby the thread floats equal or exceed 2. The result
is to advantage
a highly favorable method of producing a belt webbing in accordance with the
invention as
a tubular fabric having a defined arrangement of warp thread qualities whilst
eliminating the
need to tack belt webbing and air bag as usual in prior art.
Referring now to FIG. 2 there is illustrated in cross-section a belt webbing 2
in accordance
with the invention in which the edge portions RB are fan-folded between the
middle portions
MB. The arrangement of the belt webbing 2 symmetrical relative to the axis 10
is evident
from all FIGS. of this description. However, this is not to be interpreted
necessarily that the
belt webbing in accordance with the invention always needs to be folded in a
symmetrical
arrangement, i.e. one or the other non-symmetrical type of fold possibly being
expedient,
depending on the specifically desired final shape of the tubular belt in its
inflated condition.
As evident from FIG. 2 the fabric of the edge portions is return-folded at the
side edges 12
through roughly 180 and is guided up to roughly the middle (axis of symmetry
10) of the
belt webbing where it is again folded through 180 outwardly. In the turn of
the fabric
oriented again outwardly in the direction of the side edge 12 it is evident
that the next folding
edge comes to rest slightly further inwards in the direction of the axis 10
since the folding
edge needs to be located within the burst threads 14 joinins the outer layers
depicted by the
broken line. This reciprocating fanfolding of the fabric is continued down to
the lower woven
ply 41. the outer folded edges of which are located the same distance away
from the axis 10
as the side edges 12 of lower woven ply 41. Evident from FIG. 2 roughly in the
region of the
axis 10 is an inner space 5 of the belt webbing which as illustrated in this
case has been
selected particularly narrow. It will be appreciated, however, that this can
be handled
differingly depending on the designer requirements. As illustrated later, for
example in FIG.
5, this inner space 5 may be configured widened to one side or to botll sides,
reference again
being made to the possibility of locating the folds of the fabric non-
symmetrical as already
mentioned above.
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Referring now to FIG. 3 there is illustrated the belt webbing as shown in
FIGS. 1 and 2 just
before the expansion gas is gunned into the inner space 5 of the tubular belt
webbing. The
directions in which the fabric moves and expands can be visualized in theory
from the star
cluster arrays of the arrows 18, it being evident the remainders of the burst
threads 14 are
loosely located in the region of the side edges of the outer side 16 and the
side edges 12.
FIG. 4 illustrates the belt as shown in FIGS. 1, 2 and 3, in this case in the
inflated form
represented by the broken line.
One advantageous aspect (not shown) of the belt webbina in accordance with the
invention
consists of the warp threads handling all of the rupture loading of the belt
webbing being
incorporated in only one of the middle portions MB of a single woven ply, this
requiring, of
course, application of the required number of loadable warp threads and
selecting their
thickness accordingly. As an example, this arrangement, as applied to FIG. 2,
could be
visualized as only the middle portion MB of the lower woven ply 41
incorporating all warp
threads needed to handle the tensile force, as a result of which a softer
fabric materializes to
cushion e.g. the head impact of the passenger more gently and thus with better
protection in
the woven ply 42 facing away from the body P of the passenger.
Referring now to FIG. 5 there is illustrated a variant of a belt webbing in
accordance with the
invention having an expanded inner space 5 to make room for a gas supply
conduit 18.
It is to be noted at this point that the burst thread 14 may also be replaced
by some other
means of joining the edge portions of the tubular fabric or of the belts 41,
42, for instance by
bonding or fusing, or even some other kind of a releasable joint, such as loop
stitching. In
FIG. 7 the second belt 42 is replaced by certain warp threads 44 which are
determined to
transmit the longitudinal force of the belt 42.
The belt webbing in accordance with the invention can be put to use in any
vehicle seat, but
to particular advantage in vehicular rear seat belts, namely there, where no
suitable local
features exist for incorporating e.g. an air bag of a conventional kind. This
is why the belt
webbing is also suitable for seat belts in buses or also aircraft and
hydrofoil craft, indeed in
all applications in which passenger seats are arran'~ed one behind the other.
As alreadv
mentioned, the one or other embodiment is formulated in keepinil with the
special
requirements of the designer.
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Indicated on the right-hand side in FIGS. 1 and 2 is and additional group 30
of pairs of thin
warp threads at each side edge 12 of the belt webbing, the object of this
embodiment being
to achieve a softer configuration of the belt webbing edge to reduce wear and
tear of
passenger clothing.
A belt webbing in accordance with the invention has the enormous advantage
that as a rule
it can replace conventional belts with no problem. Where in the region of the
automatic
retractor mechanism a conventional webbing is to be fitted to a webbing in
accordance with
the invention the one and only change needed to existing seat belt systems is
to slightly
widen the webbing slot in the buckle tongue so that the slightly more bulky
webbing in
accordance with the invention can pass through with no problem, whereby, of
course, the
buckle tongue needs to be further widened should a more extensive gunning gas
supply be
needed, for instance, due to having retrofitted an integrated tubing.
EngineerinQ seat belt systems with the webbina in accordance with the
invention permits
cushioning of the passanger in all regions in which the belt is present at
all. Accordingly, it
is actually a single replacement for several air bags of the conventional
kind, namely as the
belt webbing in accordance with the invention, thus eliminating the need for a
bag for the
lap, midriff, chest, collar bone and shoulder regions as well as the so-called
headside bag.
One advantage of the inflatable belt webbing making it absolutely superior to
an air bag is
that in a crash situation the inflatable belt webbing is already in contact
with the body of the
passenger whilst the air bag first has to be gunned with a loud bang in the
direction of the
passenger in a partially uncontrolled movement.
To maintain the function of the inflated belt webbina as long as possible it
is of great
advantage to coat the belt webbing in accordance with the invention on the
inside, for
example. with silicone or polyurethane. Coating the tubular fabric may also be
achieved by
impregnation and/or dyeing when dyes on a special synthetic basis compound
correspondingly
with the fabric so that it becomes impermeable.
As already mentioned above, inflating the belt webbina in accordance with the
invention to
an hitherto unattainable, extremely large diameter acts simultaneously as a
belt tensioner.
Trials have indicated in all that using the belt webbincy in accordance with
the invention
greatly reduces the risk of specific injuries to passengers, since the force
of the belt webbing
is distributed over the full trunk of the person involved, thus areatlv
diminishina the
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concentrated force effects tending to cause injury. By engineering specific
air and gas
permeability in selected regions of the tubular fabric a controlled so-called
"dive" and thus
also a reduction in loading is achieved to advantage by the passenger diving
into the belt
being better "cushioned" by the controlled slackening of the belt webbing. The
work involved
in cushioning is better distributed, the extent of injuries reduced. Another
advantageous
method consists of providing the tubular fabric with gas exit ports in
selected regions which
have a similar effect.
Another aspect in accordance with the invention of the belt webbing as
discussed above also
consists of weaving a so-called one-piece air belt in which with the aid of a
Jaquard loom the
complete seat belt is woven from one end to the other in one piece. On wide
looms several
belt webbings in accordance with the invention may be woven juxtaposed, a
resulting
"woven" seam BWN (evident on the right-hand side of FIG. 1, for example, as an
alternative)
"vanishing" between the middle portions MB of the belt webbing 2 during
folding so that it
is not a disturbance. In this case, the regions such as e.g. the reeling
region, the thin webbing
and protection region desired in each case in the belt webbing in accordance
with the
invention can be taken into account individually in keeping with the specific
requirements of
each vehicle or aircraft manufacturer, as a result of which - as already
mentioned above - the
effects of conventional side and front air bags are assumed by a single safety
system. This
makes for high savings in production costs whilst decisively enhancing the
safety in the chest
and head region due to the compact combined solution to the problem. It will,
of course, be
appreciated that all features of a one-piece air belt can be adapted to
differin- passenger
stature and weight requirements, thus accommodating production of a child'/2s
air belt just as
well as for heavy adults in taking into account any specially desired position
and arrangement
of permeable regions of the air belt fabric as well as the desired length of
the air belt in each
case.
Yet a further advantageous aspect of the invention consists of scoring the
tubular structure of
the webbing, tubing or fabric to facilitate folding more particularly in
fabricating the belt
webbing ready for installation, this scoring being done in selected regions
along lines running
parallel to the longitudinal axis of the tubing. Fabrication is then able to
be completed much
quicker since the belt webbing tends to fold "by itself' This resultiny~ in a
substantial time
savinQ in final assemblv. whereby but slight scoring is sufficient.
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For producing such a webbing, tubing or fabric it is proposed in accordance
with the
invention to guide the tubular structure along the lines over hot ironing
edges, this being
expediently done directly after production of the webbing, tube or fabric
material, i.e. in a
condition in which the material is still to be applicated and is therfore
still relatively easy to
handle.
Another variant which is just as advantageous consists of folding the tubular
structure along
the lines prior to it being hot ironed. This can be done with an iron by
conventionally known
methods. In both methods as mentioned the material is lightly fused on being
scored and is
thus unable to fully return from the fold, thus resulting in an effect
expedient to folding.
When a woven material is made use of as the fabric, webbing or tube material
it is of
advantage to "incorporate" in the selected regions along the planned "ironing
lines" warp
threads separately engineered for this purpose, i.e. the warp thread material
itself being
selected accordingly as to its strength, capillary number and/or composition.
The type of
weave selected in the region concerned may also be decisive.
In still another advantageous aspect of the invention the webbing, tubing or
fabric is
characterized by the tubular structure being coated on the inside at least
regionally, serving to
regulate the permeability of the fabric, it being easier for the inflation gas
of the air belt to
exit from non-coated zones of the fabric than from the coated zones. Also of
particular
importance in this respect is the location of the non-coated regions since
the, as a rule, hot
inflation gas of the air belt needs to escape and exit from a region facing
away from the body
of the passenger to avoid injury by the hot gas, whereby even in the case of
cold inflation
Qases there is a risk of injury due to their shock flow velocity.
For this purpose also an advantageous method of producing a coated webbing,
tubing or
fabric in accordance with the invention is proposed which is characterized in
that the tubular
structure is provided as a substantially tubular chamber, the inner contour of
which roughly
corresponds to the outer contour of the non-folded or unfolded structure,
whereby the
chamber comprises a wall permeable to gas at least in part and in that a gas
entraining the
coating means at a pressure P; is introduced into the structure whilst outside
of the chamber
a pressure P, exists so that P; > P,. The procedure is thus actually already
described so that a
person skilled in the art can implement the method, by means of which the
local permeabilitv
of the structure can be controlled very simply. The coating means introduced
as a rule with
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a solution then deposits only in the region within the structure on the innner
wall thereof,
opposite to which a gas-permeable wall of the chamber is located. It is at
this location (these
locations) that the gas escapes from the chamber it, in doing so, "sweeping"
the coating
means (e.g. a polythene compound) from the fabric, whereas in the region of
non-permeable
zones of the chamber wall no, or hardly any, coating of the coating means
takes place on the
structure. These regions are the permeable zones (see above) in the finished
condition of the
air belt due to the "missing" coating. It will be appreciated that this method
can only be put
to use in conjunction with gas-permeable fabrics.
In the previous paragraph the coating of a tubular structure was described.
However, it is just
as conceivable to "slit" the tubular structure and to arrange it flattened out
of the inner
surface of the gas-permeable wall of a likewise "slitted" chamber, the
localities "inner" and
"outer" then becoming e.g. "upper" and "lower". Analogous to the inner space
of the
aforementioned structure a gas entraining a coating means at a pressure Po is
then applied to
the flattened out surface, whilst a pressure P,, exists on the outer side of
the wall (i.e.
underneath) outside of the charnber, whereby P. > Pu. The further procedure in
producing the
coating is then analogous to that already described for the tubular fabric.
The belt webbing may be coated after weaving prior to being folded, one option
prior to
coating being also to turn the unfolded belt webbing tubing over to the left,
after which it is
fanfolded as described above.
***
