Note: Descriptions are shown in the official language in which they were submitted.
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BRAC~ FOR PL~.STIC CPINI~;TE:I~S
1~hc in~ention relatcs to a brace ~or connectin~ the
two largcr side walls of plastic containers, more
particularly of canistcrs. Such a statc of the art
has become known, for examplc, from the US Patents
3,33~,7f.~; 3,52~,488; 3,552,59~ or thc 13rit. Patcnt
1,007,563. Containers of this kind may be stationary.
They are thcn called "tanks". They may, however, also
be portab~e. In that case they are rcfcrred to as
"canisters". Whcn thc.sc containers arc fillcd with
hi~3hly volatilc liquids such ~5, Eor cxample, ~Jasoline,
thc problem of diffusion appears. ~bove any liquid level
of this hic3hly volat:ile substance, a ~as is formed which
in the course of time diffuses through the plastic.
Moreover, thc containers bulcle - unless they are
filled compl~tely with liquid - in balloon-like fashion
under the influence of external heat. This also happens
in the case of sheet metal canisters, but not to the
same extent. The plastic canis-ters then fit no longer
into standard holders or can no 1onger be taken out of
thesc standard holders. If thc containers are fuel tanks
in motor vehicles, they do not havc to br removed.
Nevertheless, the designer must make provisior1s that the
tanks are ablc to chan~3e thcir shapc in the manner
recluircd .
In thc casc o~ stationary tar~ , for cxample, in
basements or buricd in the ~round, thc changes do not
ulay a major ~alt since it is in this casc possible to
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install VCIltS which,in contrast to t:hc tanks in motor
vchicle!;, n~vcr l)ecomc clo(~gcc1. IIC1r~ however, the
hyclrostati.c pressul^e on the sicle waLJ.s does play a part.
Another fact which plays a part in the case of
20- and 30-1 canisters is that thcy are, when dropped
from a height, br.iefly deformed into a pear-like shape
and that ~he ~alls must be capable of following this
deformatic~n without force peaks, because otherwise
additional forces would act on the walls.
~ ;enerally speaking, plastic canisters would be
supcrior to n-letal can.isters for vari.ous reasons because they
are, for eY.amplc, cons;.derab]y ~ cr in weight than
metal can.is~crs, ~k~ not l-ave ~.o l.)c ~)alnted, no rust flakes
o.Ef on the insi.cle as time cJoes on, they do not rattle, and
so on.
However, th~ efforts to stabilize the side ~lls have
thus far failed to lead -to a practical solution.
For example, it has not bcen l~ossible to produce a
practically useful brace according to Fi.g. 1 of the
Brit. Patent 1,007,5~3, because the deep-drawing ratio
is much too large and the walls of the braces are then
too thin. This applies not only to the walls of the
braces but above all to the angle rcgions. ~lowever, a
canister is only as st.rong as its weakest point. More-
over, such braces represent very -troublesomc structural
elemcnts when it i5 a question of improving the drop
resi.stance o~ canistcrs because thcy try not to yield
eithcr to terlsion or thc compressio~ i.na:l.ly, these
braces take away a very considerablc volumc. Ilowcver,
for cxam~)le, a 20-1 canister has a cJeometry specified by
standards within which 20 liters must be accommodated. This
cannot be done if part of the volume is sacrificed in other
ways.
In the case Gf the device according to U.S. Patent
3,55:2,599, an attempt has been made to eliminate the large
deep-drawing ratio by realizing the braces by two flat cones.
This, however, leads to a large loss of volume, particularly
when, for example, in the case of larger containers, four such
braces must be provided.
Here again - as in the other state of the art - the
brace must be formed of blown plastic material which, because
of the limited blowing pressures, is known to be flabby.
Although it may do for a canister wall, it performs the braclng
function very poorly. For example, at the point 76 in Fig. 5
of this U.S. patent, this material offers practically no
resistance to notch cracks.
The object of the invention is to specify a brace
which without a noticeable sacrifice in volume stabilizes the
side walls and permits a practically feasible solution.
Accordingly, the present invention provides a con-
tainer made of plastic having two larger side walls and two
smaller side walls, in combination with a brace for connecting
the said two larger side walls of the container, wherein the
said container comprises a canister for highly volatile liquids
and, wherein the said brace is formed as a separate element
of construction arranged to be set inside the said canister,
and further comprises:
i) two brace ends with one anchor plate at each
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end, the anchor plates each having an inner and an outer
surface, said outer surface being arranged to be joined to
at least a part of the inner surfaces of the canister situated
opposite each other, said anchor plates being substantially
circular and made of the same material as the said canister
side walls and,
ii) a pull-brace portion extending from the said
inner surfaces of the anchor plates, which can be stressed
under tension to a stretched state and which in the stretched
state has a length equal to the distance between the inner
surfaces of the anchor plates, said pull brace portion being
a plane wall, and being constructed in such a way that it
partially collapses when the said side walls move inward.
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'l'hc invel!tion shall now ~c ~x~)lained with the aid
o~ a prf~(rrcd embodiment. On the drawing,
Eig. 1 shows the front vicw of a 20-1 canixter,
partially cut away, with a brace and with the deforma-
tion shown in exaggerated fashi.on by a broken line -
caused by thc impact of the canister when dropped;
Pig. 2 shows a view of a secolld brace seen approxi-
mately in the direction of Fig. 1, but without the
canister associated with it;
Fig. 3 shows a vicw similar to ~ig. 2, but in a
sli~htl~ morc co:llaE)scd statc of tl;e bracc;
Eig. 4 .shows thc side view of the brace according
~o Figs. 2 and 3 in the fully collapscd state; and
Fi~. 5 shows a section along the line 5-5 in Fig. 2.
/ ~ 20-1 can.ister ll is blown or injection-molded
from plastic. It has the usual three handles 12 and a pouring
~spout 13. Following the usual pattern, its side walls 14,16
are substantially wlder than its front wall 17 and its
rear wall 18. When thcre is a pressure inside the canister,
there is the danger that thc side walls 14,16 bulge toward
the outside in a manner no-t shown. When the canister
drops on the floor, a shape results over a short period
of time accordin~ to the bro~.en lines 19. The upper part
which is more~ rigid because of numerous offsets, th~
handles 12, Lhc spout 13, etc., is hardly ~c~ormed at all
and it i5 mairlly thc .l.owcr part whi.ch is ~lcformcd.
~ lle side wa].ls 14,16 have inne:l- SUI facc.c~ 21,22. ~t
a hei~ht at which thc side walls 14,lG are de~lected
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inwarcl a hracc 23 ls [)roviclcd. ~t~e brace 23 is situated
at that level t:~ecause it thell e~erts no aclditiorlal forces
on thc sic1~ w.llls 14,1G WtliC}I wonl~l ccrtainly t~c the case
if the br~ce 23 were providec-l, for example, in the lower
belly oi thc line 19. The brace 23 is situated at the
same time in the approximatc recJion in which -the side
walls 1~,]6 woulci be forced apart when at high temperatures
the c3as mixture inside the canis-ter 11 exerts a high
pressure.
In this Eirst embodimcllt, the brace 23 has a-t its
two encls p]atcs 26,27 whose outer surfaccs 28,29 are welded
to the inner surf~ces 2].,22. In ordcr to facilitate the
welclinc3, the outcr surfaces 28,2~ hav~ small con~s (not
shown) such as have been described, for example, in the
G~rman Patent 2,151,913.
The plates 26,27 are circular. At their center, they
chan~e into a ropc 31 which is monofil and was injection-
molded simultaneously with the plates 26,27.
~ s shown in Fig. 1, the rope 31 can be stressed only
under tension; it gives way when the side walls are pressed
together which may by no mcans happen only when the canister
is dropped.
In the second embodiment according to the following
figures, the p3ates 26,27 are provicled. In addition,
there is a system of four walls 32,33,34,36 which at their
ends are integral with the plates 26,27. As shown par-
ticularly clearly in Fig. 5, the lnner eclc3es 37,38,39,41
are not cohesivc. On thc contrary, ttlere is no conncction
from one wall to the next. Thc walls 32,33,34,36 can bc
practically only a Ecw tcnths of a millimeter in thickness
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since they ar~ dcsi~lled ~xpressly only for tcnsile
strcss bul n~t for shc!ar strcss S,~ as is also the case
with the rope. The inr~er edges 37 to ~l are disposed in
such a manner that this brace 4~ can be ~abricated with a
two-piece tool with two slides. This is accomplished by
aligniJlg ~he walls 33,36 and ~y transposing the walls 32,34
in their alignment relative to the inner edges 38,41 so
that the clearance existing in between can be realized.
A clearance exists also between the inner edge 37 and the
wall 36 and one betweer, the inner edgc 39 and the wall 33.
These clearances prevent that durinc3 thc emptying of the
canistcr thc walls rctain pudc31es of liquid, depending on the
position of the callistcr.
Fox the s~lne reclsorl, each wall 32 to 36 has at the
point whe~re it adjoins th~ plates 26,27 a perforation 43.
The plates 26,27 can be brought to~ether from the configura-
tion acc~rding to E`ig. 2 via a confi~uration according to
Fig. 3 to a distance at which the ~race 42 is only a single
disk. This provides clCCeSS even into small recesses. To
this end, the wall 32, for example, has alonq the plate 26
a spccified bendinc3 line 44 which makes it possible to
jackknife the region situated -to the right of the specified
bending llne 44 in the downward direction. In the middle,
the wall 32 has a specified bendiny line 46 which acts in
the direction of a V-trough closed in thc~ downward dir~ction.
At the transition from the wall 32 to the plate 27 another
æpecified bcnding line 47 is provided which imparts to
the wall region situatecl to the left of it a tendcncy to
fol~ out of the way in the upward dircction when the
plates 26,27 approach each othcr.
All the other walls 33,34,36 have such specified bcnding
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lincs and al] the s~ecifie~ bending lines of these other
walls procluce the same tendencies. This then results in
a foldin(~ scherl~e which comes into ~ ing at a certain
al)l)rvacll oL ~lc ~ cs 26,27 accordil~g to Fig. 3. When
the plates 26,27 are brought togeth~r to their closest
distance, then only the walls ~re sandwiched between
thcm in a doublc layer. Ilowever, in no case do the
individual walls rest in addition against any o-ther walls.
If now thc outcr edges of the walls 32 to 36 were
just as rectilinear as the walls of the inner edges 37 to 41,
then the outer cdges would in the folcled state project beyond
the ylate~ 26,27. By cut-ting thcse l)rotrudinc~ cdyes off,
the rouc3hly cosin,e-like shapc of the walls shown particularly
in ~ig. 2 ,j,x formcd. ~rhe edcJcs 48,49 of the wall 33 run
on c.ircular arcs which start in eacll case outside at the
edcJe of the plate 26 or 27, resp., and then extend toward
the middle up to the respective sp~cified bending line.
~his then lcaves a cross section 50 occupying approximately
half the heic,Jht o[ tho wall 33 whicll rcprescnts the weakest
point r~hich can bc stressed under tension'.
Since there is nothing projecting beyoncl the edges S1
of the plates 26,27, the latter are easy to manipulate.
The arc-like shape of the ed'ges 48,49 w.ith the
resulting indentation according to Fig. 2 has the effect
that the plates 26,27 are connected with each o~her by a
still more univcrsal joint than if these edges 48,49
would run dir,cctly and straight from the cdge Sl of the plate
26 to l:he ecl~3e 5' of thc platc 27.
