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BACKGROUND OF THE INVENTION
Various building or similar structures have been proposed which are based
upon column-like elements or rods used as basic construction units which
function as stays. A fabric covering is usually associated with the
network of rods employed. Also, it is usual for such assemblies to have
foldable/extensible capability so that they may be extended/erected where
desired and, when necessary, folded up to a rather compact form for
storage and/or transportation. Other structures of this general nature are
intended to remain in place once erected and within this category are what
is known as geodesic structures.
Generally speaking, where the structures are intended to remain in place
once erected, the rods or column-like element are rigidly joined together,
whereas for the extensible/foldable structures these rods ordinarily are
joined pivotally. Examples of extensible/foldable structures are found in
the Pinero Pat. No. 3,185,164, the Greenberg et al Pat. No. 3,496,687 and
the Kelley et al Pat. No. 3,710,806.
The patents are exemplary of the fact that the prior art in order to
achieve an extensible/foldable capability has found it necessary to resort
to various types of extraneous locking means. For example, in the Pinero
patent not only is a system of cables a,b necessary to form the extended
shape of the structure, but cables c are also required to hold such shape
(i.e., to render the structure self-supporting). The Kelley et al patent
represents another basic approach and that is to provide hub-connected
scissors linkages.
In all of the prior art devices, except in those instances where positive
locking means are used, the structural integrity of the extended, erected
structure is not great and none employs an arrangement wherein structural
integrity results from a relationship among the rod-like elements which is
attained by and incidental to the erected shape itself and which does not
rely upon physical constraint of the pivotal connections among the rod
elements.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to a framework arrangement which is
self-supporting when erected while being at the same time characterized by
the fact that free pivotal connections among the column-like elements is
possible. That is to say, the arrangement herein derives self support by
virtue of and in natural consequence to the shape which is assumed when
extended into fully extended form. A fabric covering may be employed but
the self-supporting relation does not rely upon such covering. The
rod-like elements may remain freely pivotally interconnected at all times
and whereas the extended structure may be rigidified by extraneous means,
it does not rely thereon for the basic self-supporting relation naturally
attained.
Basically, the present invention employs a network of pivotally joined
elements in which coordinated groups thereof are pivotally joined at
corresponding ends thereof, the groups being paired such that the elements
of one group of each pair intersects to define an inner apical point
whereas the elements of the other group of the pair intersect to form an
outer apical point. The outer of these pairs of apical points are
distributed over and within a surface of revolution such as a semi-sphere
with elements of adjacent groups being joined such that any pair thereof
extending from one outer apical point to an adjacent outer apical point
having a further outer apical point intervening (the element-pair in the
process intersecting at an inner apical point corresponding to the
intervening outer apical point) lie in a straight line. Other
element-pairs intersecting at the inner apical point corresponding to the
intervening outer apical point lie in a common plane containing the
first-mentioned element-pair. This is a basic characteristic of the
present invention.
A further basic feature of the present invention resides in the fact that
further element-pairs are crossed and pivotally joined between their ends
and are end-connected pivotally to other such crossed pairs. In any
structure of this invention these will be strings of such crossed pairs of
elements (i.e., a "ladder" thereof) extending arch-like within the
structural shape, in which certain ones of the pivotal connections between
crossed elements are omitted. This feature allows a full extension/folding
capability without sacrificing the natural self-supporting feature.
Moreover, this relationship results in a "programmed" extension or folding
of the framework such that a simple, fixed procedure may be followed
either to extend or to collapse the framework.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
FIG. 1 is a perspective view, partially broken away, showing one form of
the invention;
FIG. 2 is a perspective view of the assembly of FIG. 1 in folding
condition;
FIG. 3 is a perspective view showing a portion of the framework of FIG. 1;
FIG. 4 is a plan view of a portion of the framework;
FIG. 5 is an elevation showing a portion of one ladder string;
FIG. 6 is a view of the ladder string of FIG. 5 as it is being folded;
FIG. 7 is a view showing the ladder string in folded condition;
FIG. 8-11 are sequentially folded configurations of a portion of the
framework;
FIG. 12 is an enlarged section showing a universal pivot connection with
cover mount;
FIG. 13 is a plan view of the connection of FIG. 12;
FIG. 14 is a perspective view of one element and the hinge wire;
FIG. 15 is a perspective view of a modification of the invention which may
be used to obtain increased strength where desired;
FIGS. 16-18 illustrate a modification employing inner and outer cover
material;
FIGS. 19 and 20 illustrate another form of the invention;
FIGS. 21 and 22 illustrate two forms of the invention where the surface of
revolution is carried out over 360.degree.;
FIGS. 23 and 24 show the folded configuration of FIGS. 21 and 22
respectively;
FIGS. 25 and 26 are diagrammatic views illustrating certain principles in
connection with FIG. 1; and
FIG. 27 illustrates a further embodiment of the invention.
DETAILED DESCRIPTION
Referring to FIG. 1, the self-supporting structure is indicated generally
by reference character 10 and includes a network of column-like elements
defining the framework 12 which may be provided with a fabric or other
suitable covering 14, half of which has been removed in FIG. 1 to expose
the underlying framework.
As will appear more clearly as this description proceeds, the structure
shown in FIG. 1 may be collapsed or folded down to the compact bundle 16
as illustrated in FIG. 2.
Structures according to this invention are characterized by the fact that
they define generally a surface of revolution, the form shown in FIG. 1
being semi-spherical with the pole thereof indicated by the broad arrow
18. With this pole as a reference, certain basic relations of the
invention will appear more clearly from FIG. 3. In this form of the
invention, two groups of elements intersect at the pole, one group
consisting of the elements 20, 22, 24, 26 and 28 which intersect and are
freely pivotally joined at the outer apical point 30, and the other group
consisting of the elements 32, 34, 36, 38 and 40 which intersect and are
freely pivotally joined at the inner apical point 42. The outer and inner
apical points 30 and 42 define a corresponding pair thereof and other
corresponding pairs of outer and inner apical points are indicated at 44,
46; 48, 50; 52, 54; 56, 58; 60, 62; 64, 66; 68, 70; 72, 74; 76, 78; and
80, 82. It is a feature of this invention that the outer apical points lie
on the aforesaid surface of revolution and that each corresponding pair of
outer and inner apical points lie in alignment along a line normal to such
surface of revolution, i.e., the pair 30,42 lies in alignment along the
pole 18.
Another feature of this invention is that the network of elements is such
that the individual elements of the aforesaid groups thereof radiate from
their corresponding apical points to join pivotally with other elements at
other apical points. Thus, the element 22 for example radiates from its
outer apical point 30 to join pivotally with the elements 82, 84, 86 and
88 at the inner apical point 58. Similarly, the element 34 for example
radiates from the inner apical point 42 to join pivotally with the
elements 90, 92, 94 and 96 at the outer apical point 56. The outer apical
points are distributed regularly over the surface of revolution and
between each adjacent set of outer and inner apical point pairs a crossed
pair of elements extends. For example, the crossed pair formed by the
elements 22, 34 extends from the apical point pair 30, 42 to the apical
point pair 56, 58 thus forming an adjacent set. At least for the most
part, as set forth hereinafter, these crossed pairs are pivotally joined
intermediate their ends, i.e., where they cross, the crossed pair 22, 34
for example being pivotally joined in scissors-like fashion by the pin 98.
It is further characteristic of this invention that each group of elements
associated with and radiating from each inner apical point and extending
therefrom to adjacent outer apical points lies in a common plane. Thus,
the group of elements defined by the individual elements 22, 82, 84, 86
and 88, for example, which "belong" to the inner apical point 58 lie in a
common plane and extend to the adjacent outer apical points 30, 44, 52, 56
and 60. This basic relationship repeats throughout the network and serves
to define the relationship among locations of all the apical points and
lengths of the elements. In this connection, it is possible to have all
elements of the same length and for at least the majority of elements
employed this is a desideratum. However, in the specific form shown in
FIG. 1, the elements closest to the pole 18 are of lesser length, as will
appear hereinafter.
When the combination of short and long elements is used, as in FIG. 1, the
relationship which must prevail is shown in FIG. 4. As shown, the
imaginary circles 100, 102, 104, etc. centered upon the axes of the apical
point pairs must mutually touch at the crossing points of the element
which, in turn, defines the lengths of the elements. Thus, in FIG. 1 there
are three element lengths involved, the shortest being those radiating
from the apical point pair 30, 42; an intermediate length associated with
circles 102 grouped around the pole 18; and the standard length associated
with all the remaining circles 104.
By following the relationship above noted, the network will include a
number of scissors-like chains or ladders in which a series of crossed
pairs of elements extend arch-like within the network, which ladders
encompass at least substantially all of the elements in the network. To
exemplify this, in the form shown in FIG. 1, some of the legs 106 and 108
of two routes followed by the aforesaid arch-like ladders are shown, it
being appreciated that other ladders or routes parallel to these are
present in the network.
In each of these ladders, pairs of end joined rods lie essentially in axial
alignment, i.e., along a straight line where the structure is erected and
the joining points of these element pairs define the inner apical points,
the other elements joining at such inner apical points lying essentially
in a common plane whereby each group of elements radiating from an inner
apical point extending to those outer apical points which lie in
surrounding relation to the outer apical point associated with such inner
apical point.
To illustrate a ladder structure and the manner in which it contributes to
the self-supporting feature while also participating in the folding
action, reference is had to FIGS. 5-7 which related to an embodiment
employing the principles of FIG. 27, hereinafter described. In these
Figures, the network of elements is somewhat different from that shown in
FIG. 1 in that all of the ladders passes through a pole of the structure.
Only that portion of the chain or ladder is shown which consists of the
crossed pairs of elements 138, 140; 142, 146, 148; and 150, 152. The
elements 140 and 144 form two elements of a group radiating essentially in
a common plane from the inner apical point 154, likewise for the two
elements 142 and 148 associated with the inner apical point 156, likewise
for the two elements 146 and 152 associated with the inner apical point
158, and so on for all of the inner apical points associated with the
scissors chain. All of the crossed pairs of elements shown in FIGS. 5-7
are pivotally joined at their crossing points but in order to be
collapsed, each ladder must have two of such crossing points free to
slide, the sliding points being located equidistantly from the central
point of the ladder. FIGS. 5-7 also illustrate three basic lengths of
elements and associated circles 100', 102' and 104 similar to FIG. 4.
With the sliding points as described, a downward pull on the central inner
apical point 154 causes all of the inner apical points 154, 156 and 158 to
retreat downwardly while their corresponding outer apical points 160, 162
and 164 rise outwardly as shown in FIG. 6. That is, the element pairs 140,
144; 142, 148; and 146, 152 begin to vee downwardly out of their aligned
or straight line condition. FIG. 7 illustrates the ladder in its fully
collapsed or folded condition with all of the outer apical points
retreating toward the central outer apical point 160 and all of the inner
apical points likewise retreated toward the central inner apical point
154.
FIGS. 5-7 illustrate a further principle of the invention which is
necessary in order to establish the folding relationship at each pair of
inner and outer apical points. To illustrate this principle, reference is
had to FIG. 6 wherein pivotal points joining crossed pairs of elements are
indicated at 322, 324, 325 and 327. In order to achieve the folding
relationship, the distance from an outer apical point, say the apical
point 160, to a pivoted crossing point 324 plus the distance from the
corresponding inner apical point 154 to this same pivoted crossing point
324 must be equal to the distance between 160 and 322 plus the distance
between 322 and 154. These relationships must hold for all crossed pairs
of elements associated with each pair of inner and outer apical points.
This will explain why, for example, the crossed pair of elements must be
left out between the apical point pairs 56, 58 and 72, 74 in FIG. 4 if the
structure is to fold. In FIG. 4, the two circles 102 and 104 are not
tangent, but overlap. Thus it is not possible for the above distance
relationships to hold for a crossed pair of elements joining the apical
point pairs 56, 58 and 72, 74 because they could not be the same as those
distance relationships which prevail for the other crossed pairs shown,
i.e., those joining the apical point pairs 56, 58 and any other apical
point pair which is not the pair 72, 74.
To allow the network to be folded into the compact bundle of FIG. 2, it is
necessary that each ladder have two points along its length where the
pivot connections of crossed elements is omitted or removed. This
relationship, followed throughout the network along a path 110 centered on
the pole 18 in FIG. 1, produces a controlled and multi-stage
extension/folding of the framework is shown and for all crossed element
pairs illustrated except for those at crossing points 112 and 114, pivotal
connections are made at the crossing points. By depressing the inner
apical point 42 at the central apical point pair 30, 42 the adjoining
elements will first flex as indicated by dashed lines in FIG. 8 so as to
shorten the effective lengths of these elements and the aforesaid coplanar
relationship among elements of the various groups in which the elements
are so related, will begin to collapse for it is these coplanar groups
which contribute strongly to the self-supporting feature of the framework.
Once this begins to occur, as permitted by the relative sliding allowed at
the points 112 and 114 as illustrated in FIG. 9, the entire center,
inwardly of the points 112 and 114, will collapse downwardly onto the
supporting surface as shown in FIG. 10. The omission of the dashed line
elements in FIG. 8 allows the structure to move in the directions of the
arrows in FIG. 10 as the structure thus collapses and then, by pushing
radially inwardly around the base of the structure, all of the crossed
elements will close in scissors fashion to "retreat" to the center as
shown in FIG. 11, the entire framework undergoing the above throughout so
as to create the bundle of FIG. 2.
A preferred universal pivotal connection at the apical points is
illustrated in FIGS. 12-14. As shown, each element has a double-ended fan
flot 130 through which a wire ring 132 passes so as to allow universal
movement of the rod elements. In the embodiment of FIG. 1, there may be as
few as three elements intersecting at an apical point and as many as six
elements, as shown. The central void in FIGS. 12-14, since this is an
outer apical point, is filled by the hub 133 of a flanged sleeve and the
step 134 of a button having an enlarged head 136 is projected through the
bore of the hub 133. The distal end of the stem 134 is provided with a
transverse bore to receive a securing pin 138 or like member, holding same
in place.
The hub member 133 is surmounted by a flange 180 and as will be seen in
FIG. 12, this flange and the enlarged head 136 sandwich the covering
member 14 therebetween plus serving to anchor same in place at the outer
apical points. For the inner apical points, the flanged hub member 133
only is utilized. The hub member includes a plurality of radially
projecting webs 182 which serve to stabilize the wire ring member 132 and
hold all of the rod like elements in proper relationship relative to each
other, the inner side of each of the webs 182 being notched as indicated
in FIG. 12 to receive the wire ring 132 therewithin to effect the snap
action reception of the wire ring within the notches thereby to stabilize
the assembly.
As illustrated by the four arrows in FIG. 14, each of the rod elements is
capable of universal movement relative to the others by virtue of the
double fan opening 130 and at the reception of the wire ring 132
therethrough.
Whereas FIG. 12 illustrates an embodiment wherein an outer covering portion
14 is utilized over the structural framework, the manner in which inner
and outer covers may be utilized as illustrated in FIGS. 16-18. In these
Figures, three outer apical points 184, 186 and 188 are illustrated and
their corresponding inner apical points 190, 192 and 194 with
corresponding portions of the inner and outer cover sheets 196 and 198. It
will be appreciated that the pattern of elements illustrated in FIGS.
16-18 is repetitively present throughout the structure even though only
two elements associated with each apical point are illustrated for the
sake of clarity. As illustrated, the pair of rod elements 200, 202 cross
and are pivotally joined at their point of crossing, likewise for the pair
of elements 204 and 206 and for the pair of rod elements 208 and 210. When
the inner apical points 190, 192 and 194 retreat inwardly and the
corresponding outer apical points retreat outwardly as is shown in FIG.
17, the corresponding portions of the covers 196 and 198 pluck inwardly in
the manner illustrated in FIGS. 17 and 18 by virtue of the flexible inner
connecting member 212 which serves to join the geometrical center portion
of that section of the covers 196 and 198 within the triangle defined
between the corresponding apical points, as is shown.
FIG. 15 illustrates an alternate embodiment of the invention which may be
utilized to obtain an increased rigidity and augmented self-supporting
function. In FIG. 15, the outer apical point 220 and the group of elements
222, 224, 226, 228, 230 and 232 associated therewith radiate to the
surrounding inner apical points 234, 236, 238, 240, 242 and 244 whereas
the group of elements 246, 248, 250, 252, 254, and 256 which intersect to
form the inner apical point 258 cross and pivotally joined to
corresponding elements of the first mentioned group but are slightly
longer toward their inner ends than the group of elements associated with
the outer apical points 220 so that the inner ends of this group of
elements associated with the inner apical point 258 deflect or deform
inwardly somewhat as is illustrated in FIG. 15 when urged to such position
so as to further rigidify the assembly. Thus, opposed elements such as 256
and 250 are aligned and form essentially a straight line, as before, but
their inner ends are slightly deformed out of the common plane otherwise
containing the group of elements associated with the inner apical point
258. In order to collapse the assembly, it is necessary to snap the inner
apical point 258 inwardly as shown in dotted lines in FIG. 15 and,
whereever this configuration is used, the increased rigidity thereof may
be very valuable where unusually heavy loads are expected for the
assemblage. For example, in FIG. 1, a configuration such as is shown for
FIG. 15 may be utilized at desired special points, as for example at the
apical point 260 as is illustrated in FIG. 1. On the other hand, a
structure such as shown in FIG. 15 may be used by itself or combined with
other, similar structures to provide an undulating structure which however
lies on a flat surface. In such case, each configuration of FIG. 15
requires separate unlocking to collapse the structure.
FIGS. 19 and 20 illustrate a further embodiment of the invention wherein
the outer apical points thereof lie again in a surface of revolution at
this time the surface is not spherical except at its end sections, being
cylindrical in the intermediate or intervening portion defined between the
two apical points 262 and 264 which in fact form the poles of the
structure. As will be evident from FIG. 19 and was described hereinbefore,
the ladders or chains of scissors-like elements pass directly through the
poles at the apical points 262 and 264. Otherwise, the principles
previously described are utilized in the configuration of FIG. 19. FIG. 20
indicated generally by the reference character 266 the compact, folded
configuration of the collapsed assembly of FIG. 19.
FIGS. 21 and 22 illustrate that the surfaces of revolution may be completed
throughout the full 360.degree. of rotation. Thus, in FIG. 21, the
spherical shape has two poles 268 and 270 which can collapse inwardly
toward each other ultimately to provide the compact folded configuration
indicated generally by the reference character 272 in FIG. 23. In FIG. 22,
the complete surface of revolution of the embodiment shown in FIG. 19 is
illustrated, same having four poles 274, 276, 278 and 280 at which the
inward collapsing of the structure is effected ultimately to provide the
compact, folded assemblage as is illustrated generally by the reference
character 282 in FIG. 24.
Referring more particularly at this time to FIG. 25, certain principles of
the construction according to FIG. 1 will be apparent therefrom. The FIG.
1 construction may be further explained in terms of conventional geodesic
nomenclature. Specifically, the FIG. 1 embodiment is constructed as a four
frequency icosahedron in which one of the triangular regions is
illustrated in FIG. 25 and, in FIG. 26, all of the triangular regions are
shown but laid out in flat form so as to give a better understanding of
the elements involved. In FIG. 25, the various points A, B, C, D and E are
depicted and it will be understood that all of the triangular regions 300,
302, 304, 306 and 308 in FIG. 26 are, in FIG. 1, joined at a common point
which is represented at the pole 18. To correlate FIGS. 1 and 26, the
triangular region 300 has its points designated by prime letters and the
triangular region 310 immediately therebelow has its points E' and D'
designated as shown, thus illustrating that the base of the structure in
FIG. 1 is cut off along the dashed line in FIG. 26, the region 310 thus
being as shown of truncated triangular form. Specifically, regions such as
310 are cut off at the second division of the side of the triangle shown
in FIG. 25 (i.e. at the second of the four frequencies or subdivisions
shown).
In FIG. 25, the symbolic representation illustrated at 312, the double line
between the points A and 314 is used throughout this Figure to indicate a
scissors-connected pair of elements and the dashed circle indicated at 316
symbollically represents the couterpart of the circle 100 in FIG. 4 while
the lightweight circles as at 318 correspond to the circle 102 in FIG. 4
while the heavy line circles 320 correspond to the circle 104 in FIG. 4.
The significance of these three circles in FIG. 25 is identical to that
represented by the circles 100', 102' and 104' in FIG. 5. That is to say,
all of the circles in FIG. 25 represent circles whose diameter is equal to
the distance between the crossing points 322 and 324 of joined
scissors-pairs of elements as is illustrated in FIG. 5. Thus, as is in
FIG. 5, the pivotal connection between the elements 142 and 144 lies
somewhat closer to the left-hand ends of these elements than it does to
the right-hand ends. Similarly for the scissors-pair 146, 148. From FIG.
25 it will be noted that the circle pair 318, 320 overlap as a natural
consequence of the icosahedron configuration and whenever this occurs, the
crossed pairs of elements are left out between the apical points in
question, as was discussed in conjunction with FIG. 6. Thus, in FIG. 25,
there are six pairs of crossed elements which are omitted and in this
embodiment such is essential in order to have the structure fold. The
omitted pairs of crossed elements are clearly evident in FIGS. 1 and 4.
In addition, there are five other pairs of crossed elements which are
omitted from the embodiment of FIG. 1 and each of these occurs for the
truncated triangular regions designated by the reference characters 310,
326, 328, 330 and 332 as shown in FIG. 6. The region of the omission of
this pair from the region 326 is illustrated generally by the reference
character 334 in FIG. 1 and it will be seen from FIG. 6, that this omitted
pair in each instance corresponds to the crossed pair location indicated
at 324 in FIG. 25. The reason for the omission of these five crossed pairs
is that, girthwise of the structure, there would otherwise be provided a
continuous chain or ladder of crossed element pairs and the structure
would not fold without the omission noted. The single exception for this
is the continuous chain of crossed element pairs which is at the base of
the structure as will be clearly evident from FIG. 1 which, it has been
found, can be left intact without detracting from the folding or
collapsing feature.
An embodiment of the invention which employs a greater number of rod
elements is illustrated in FIG. 27, which corresponds to the layout of
FIG. 25. In embodiments employing the basic arrangement of FIG. 27, it
will be noted that there are six of the largest circles 104", six of the
intermediate size circles 102" and three of the smallest circles 102", all
of which are tangent as shown and which allows, for those triangular
regions of the icosahedron joining at the pole, the use of all of the
pairs of crossed rod elements as shown in FIG. 27. To correlate FIGS. 5
and 27, the element pairs shown in FIG. 5 extending from the pole are
identified in FIG. 27 at their corresponding diagrmmatically illustrated
regions. For the truncated triangular regions (i.e., FIG. 26) either the
two pairs of crossed elements 340 and 342 or the crossed pair 344 are left
out in order to prevent the occurrence of an uninterrupted girthwise
extending chain of cross elements as described above.
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