Pressurized container of compound material

A pressurized container of compound material, such as fiber compound matel for holding a pressurized fluid in said container has a torus shaped body with a fluid tight inner container member and an outer supporting winding shell for relieving the inner container member of stress. The outer winding shell is made, for example, of fibers, threading or wires forming the winding and held together by a binding agent such as a resin or epoxy resin. The torus shaped body has a gusset type angular shape along or around its small inner circumference, whereby a furrow is formed. A further support winding (6) is located in said furrow around the small circumference and extends normal to the meridian. The supporting winding shell (5) extending around the torus shaped body and the further support winding (6) extending around the small circumference of the torus shaped body cooperate in achieving an optimal stress distribution and thus a very advantageous load distribution between the inner container member and the outer supporting winding shell.

FIELD OF THE INVENTION 
The invention relates to a pressurized container of compound material, 
especially a container having a torus shaped body made of a fiber compound 
material or a thread or wire compound material. In such compound materials 
the reinforcing fibers, or threads or wires are embedded in a binding 
agent such as as suitable resin matrix or the like. 
DESCRIPTION OF THE PRIOR ART 
A container of the just mentioned type for holding fluids under pressure 
has been disclosed in U.S. Pat. No. 4,475,662. Such a pressure container 
has a torus shaped body, but in the zone of its equator it has a 
cylindrical outer contour which is reinforced by an additional support 
winding extending normal to the meridian. 
The cylindrical outer contour and the additional support winding in the 
equator zone assure an optimal winding application and the desired 
strength that such lightweight torus containers must have. However, the 
cylindrical outer contour has its limitations in that such containers 
cannot be used for all purposes, for example. 
U.S. Pat. No. 3,293,860 discloses a container for holding a fluid under 
pressure and the container is equipped with connector means such as inlet 
and/or outlet ports for filling and/or empty-ing such containers. Such 
connector means may also include handles or the like. 
OBJECTS OF THE INVENTION 
In view of the above it is the aim of the invention to achieve the 
following objects singly or in combination: 
to construct a torus shaped pressurized container which is not limited to a 
cylindrical equatorial zone and which nevertheless is lightweight and 
capable of holding substantial internal pressure; 
to take full advantage of the so-called breaking length of the reinforcing 
materials such as synthetic fibers, threads, or wires in the construction 
of such pressurized containers; 
to avoid the problems of over-concentration of the reinforcing material, 
for example at the pole caps of prior art containers; and 
to construct an inner container member and the outer support winding shell 
in such a manner that an optimal load distribution is achieved so that the 
inner fluid tight container also participates in taking up at least part 
of the load while simultaneously functioning as a winding core and a 
sealing for the external winding shell. 
SUMMARY OF THE INVENTION 
A pressurized container having a torus shaped body of compound material for 
holding a pressurized fluid includes an inner flud tight container member 
and an outer winding shell surrounding the inner fluid tight container 
member for supporting the latter. Connector means such as inlet and/or 
outlet nipples or ports and/or holding members or handles or the like are 
secured to the container. The torus shaped body has a large and a small 
circumference relative to the torus center and accordingly, a large and 
small diameter. Such a container has been improved according to the 
invention in that the meridional planes through the torus shaped body have 
a gusset type angular shape along the small torus circumference forming a 
furrow along the small torus circumference. A further supoort winding in 
addition to the outer shell winding is located in the furrow and extends 
substantially perpendicularly or normal to the meridional planes for 
reinforcing the container along its small circumference. 
It has been found that by providing the meridional planes of torus shaped 
container bodies with a reinforced gusset shape, the advantageous 
characteristics of torus shaped containers having an oval meridional 
curvature have been substantially improved. In torus shaped bodies having 
meridional planes of completely oval curvature additional stress occurs in 
the zone of the smallest diameter or circumference. Such additional stress 
is now completely under control by the gusset shape in the small diameter, 
or rather small circumferential zone. The angular or furrow shape forms 
with the oval an endless meridional curvature. The additional support 
winding which extends preferably exclusively perpendicularly to the 
meridional plane utilizes the tension characteristics in this zone in an 
advantageous way. 
The features of the invention permit constructing a pressurized container 
of extremely light weight which fully utilizes the high break length of 
the reinforcing material such as a fiber material which requires only a 
small proportion of binding agent such as an embedding resin matrix 
without the need for heavily constructed connector nipples or sockets and 
without the need for polar caps. Another advantage of the present 
structure is seen in that the problems encountered with different 
container shapes resulting from the concentration of the reinforcing 
material such as the reinforcing fibers in the pole cap zones have been 
avoided. 
Another advantage of the invention is seen in that the load proportion that 
now may be taken up by the outer support winding shell may now be larger, 
relative to the load proportion taken up by the inner fluid tight 
container member, than was possible heretofore. This larger load take up 
by the outer support winding shell is now possible independently of any 
other limitations to which prior art containers may have been subject, for 
example the fiber concentration in the pole caps. According to the 
invention the inner fluid tight container member may take up about 20% of 
the entire load or stress while the remaining 80% are taken up by the 
outer support winding shell. Simultaneously, the inner container member 
functions as winding core and as a seal for the outer support winding 
shell. These advantages have been made possible because the inner 
container has been adapted fully in its shape to the stress conditions to 
which the entire torus shaped container body is exposed. 
By using the inner fluid tight container member, for example in the form of 
an inner tube or rubber bubble, it is now possible to manufacture the 
outer support winding shell in a continuous winding operation because it 
is no longer necessary to remove a winding core when a winding of the 
outer shell is completed as has been necessary heretofore, also for the 
purpose of the subsequent insertion of the inner tube or rubber bubble. 
Another advantage of the invention is seen in that the above mentioned 
connector means such as inlet and/or outlet nipples and/or handles or the 
like can be integrated directly into the winding structure without 
diminishing in any way the strength of the pressurized container. These 
connector means or members such as nipples, handles, or the like may be 
secured to reinforcing ribs or spars which replace the outer winding shell 
between adjacent meridional planes and which extend in the direction of 
the meridian, that is, all around the torus shaped body. Another 
possibility of securing such nipples, handles or the like is to integrate 
reinforcing lugs or splice straps directly into the outer winding shell 
and to connect the connectors through these lugs or straps. Preferably, 
the lugs or straps are arranged in a zone of small density of the 
reinforcing material such as fibers, threads, or wires which means that 
the lugs or straps are located in the outer support winding shell where it 
has its maximum diameter, namely around the outer circumference. The 
reinforcing lugs may be integrated into the outer winding shell by 
modifying the outer windings into a cross-over winding arrangement passing 
over the shoulders of the reinforcing lugs, whereby the cross-over winding 
replaces the regular winding along the meridian in this zone where the 
reinforcing lug is located. The reinforcing splice straps are also part of 
the outer winding shell and are spliced into the outer winding shell so 
that the strap or straps from an extension of the outer winding shell.

DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF THE BEST MODE 
OF THE INVENTION 
FIGS. 1 and 2 show a pressurized container 1 having a torus shaped body 2 
forming an endless ring having meridional planes M which can be extended 
through the torus center 22. Within the meridional planes M the torus 
shaped body according to the invention has a substantially oval 
cross-sectional curvature as best seen in FIG. 2, especially toward the 
equator zone 23 defined by the large diameter 20 of the torus shaped body. 
However, as taught by the invention, the cross-section curvature in the 
zone near the small diameter 21 has a gusset type angular shape 3 forming 
a furrow 3a as shown in FIG. 2. This furrow 3a forms a discontinuity or 
jump in the curvature which defines the cross-sectional meridional plane. 
The container 1 comprises a fluid tight inner container member 4 which is, 
for example, an inner tube of metalic alloy (Mg--Al), which simultaneously 
functions as a winding core for the outer winding shell which surrounds 
the inner fluid tight container member for supporting it. The outer 
winding shell 5 comprises, or rather is made of, reinforcing fibers or 
windings 5', for example carbon fibers embedded in a suitable resin 
matrix. The fibers 5' forming the outer shell 5 run all around the torus 
shaped body 2. Only a few windings 5' are shown symbolically in FIG. 1. 
The fibers 5' and their embedding matrix are directly applied to the inner 
container member 4 and all the fibers, threads or the like run exclusively 
in the meridional direction M. 
The fluid tight inner container member 4 comprises a radially inner section 
4a and a radially outer section 4b which are welded or otherwise 
interconnected in a fluid tight manner along a seam 4c shown in FIG. 2. 
Prior to joining the two sections 4a and 4b to each other, a further 
support winding 6 is applied to the radially inner section 4a near the 
small diameter zone so that this winding 6 comes to rest in the furrow 3a 
as best seen in FIG. 2. The individual windings or turns of the winding 6 
extend substantially perpendicularly to the meridional plane which means 
normal to the plane of the drawing of FIG. 2. In FIG. 1 only a portion of 
the radially innr zone or rather gussets 3 near the small diameter 21 is 
shown to be provided with the further windings 6. However, these windings 
6 extend all around the gusset 3. 
The material for forming the fluid tight inner container member 4 and the 
material of the supporting windings 5 and 6 is so selected that the 
respective elasticities provide the same absolute expansion or stretching 
under the occurring stress or load conditions. The inner container member 
4 may be of a very lightweight construction since essentially it is 
required to have a strength just sufficient to function as the winding 
core for the supporting windings 5 and 6. 
The torus shaped body constitutes an optimal configuration for the inner 
container member 4 and for the outer support windings 5 and 6. The outer 
support windings 5 and 6 and the inner container member 4 are all subject 
to nonuniform load or stress conditions and the torus shaped body is 
optimally adapted for such non-uniform load applications. Further, the 
torus body 2 has all the advantages of an endless torus body with regard 
to the application of the windings of the outer support shell 5. 
Specifically, the concentration of reinforcing fibers or the like in pole 
caps is avoided. Further, concentrations of windings with a high binding 
agent content are also avoided. This type of structure is easily 
manufactured by a continuous winding of the fibers or threads 5' forming 
the outer support shell 5 and the finished product has a uniform expansion 
or stretching in any direction and at any location. The tangential and 
meridional tensile vectors in the wall of the inner container member 4 
under load conditions are thus constant and the tensile or stress loads in 
the reinforcing fibers in the shell 5 and in the further support winding 6 
are constant. Yet another advantage is seen in that the high break lengths 
of the fiber material such as carbon fibers can be optimally utilized in 
such a container shape. 
As shown in FIG. 1 the container 1 comprises a plurality of connector 
elements 7, for example, for securing the container to a structure and/or 
for filling and/or emptying the container with a fluid. Thus, these 
connector members 7 may be in the form of nipples or inlet and/or outlet 
ports or they may be in the form of a threaded member suitable for 
connecting the container to a structure. These connector members 7 are 
arranged in or on reinforced or reinforcing spars or ribs 8 surrounding 
the inner container member 4 and taking in this zone the place of the 
respective winding shell portion of the winding shell 5. Normally, there 
will be one or two of such reinforcing spars or ribs 8. Advantageously 
these spars or ribs 8 are stronger relative to the supporting winding 
shell 5, but the spars or ribs 8 are also formed as winding bodies and may 
be considered as being a reinforced part of the shell 5. The connector 
members 7 are secured by an adhesive bond in these spars or ribs 8 as they 
are being manufactured, for example, during the winding operation. These 
spars or ribs may also be made from prefabricated mats, whereby again the 
connector members 7 are incorporated into the mats prior to their curing 
or the like, whereby the curing of the resin matrix bonds the connecting 
members 7 to the spar 8. 
FIG. 3 illustrates a pressurized container 1' corresponding substantially 
to that shown in FIG. 1, except that the connecting members 7' in FIG. 3 
are secured to a reinforcing lug 9. The container of FIG. 3 also has a 
torus shaped body 2 with an outer support winding shell 5 and a gusset 3' 
in which the further reinforcing winding 6' is located. The reinforcing 
lugs 9 are located radially outwardly in the large diameter or large 
circumferential zone and are secured to the winding shell 5a by changing 
the regular winding into a cross-over winding 10 which secures the 
reinforcing lug 9 directly into the shell 5a when the synthetic resin 
matrix cures. Thus, in the zone 11 where the reinforcing lug 9 is located, 
the cross-over windings 10 take the place of the regular windings forming 
the shell 5a. The connector members such as emptying and/or filling 
nipples 7' are conventionally secured to the reinforcing lug 9. 
FIG. 4 illustrates a sectional view through a portion of a further torus 
shaped body of a pressurized container 1" having an inner fluid tight 
container member 4" surrounded by an outer support winding shell 5" with 
the windings again directed in the meridional direction. Connecting 
members, for example in the form of filling nipples 12, are connected to 
the inner container member 4" and pass through the shell 5". A reinforcing 
splice strap 13 forming part of and being spliced into the outer winding 
shell 5" holds the nipples 12 in place. These splice straps 13 are located 
between two adjacent meridional planes and the splicing is accomplished by 
running certain of the reinforcing fibers of the shell 5" at a spacing 
from the other fibers forming the shell 5" as shown in FIG. 4. The splice 
straps 13 themselves may be pieces of a light metal, for example, aluminum 
or the like provided with bores for the insertion of the nipples 12. 
Although the invention has been described with reference to specific 
example embodiments, it will be appreciated, that it is intended, to cover 
all modifications and equivalents within the scope of the appended claims. 
For example the container may be used for pressurized gases or liquids in 
space applications.