US 3811633 A
A collapsible tubular extendable structure comprising four walls wherein two oppositely disposed walls are formed by a pair of elongated ribbons, all of which are joined along their longitudinal edges forming a plurality of cusps allowing the structure to be folded flat and wound into a coil having the width thereof approximately equal to the diameter of the structure in an extendable mode. Four of the cusps are provided with means to permit positive control when the structure is being extended.
Description (OCR text may contain errors)
United States Patent [191 Cummings et al.
[451 May 21, 1974 I TUBULAR EXTENDABLE STRUCTURE  Inventors: Alan F. Cummings, Downey; Gene G. Freeman, Santa Ana, both of Calif.
 Assignee: Rockwell International Corporation, El Segundo, Calif.
 Filed: Oct. 20, 1972  Appl. N0.: 299,568
 U.S. Cl. 242/54 A, 52/108  Int. Cl B65h 75/34, B65h 75/48  Field of Search 242/54 A; 52/108  References Cited UNITED STATES PATENTS 3,669,368 6/1972 Bell 242/54 A 3,589,632 6/1971 Rew 242/54 A X 3,361,377 1/1968 Trexler, Jr. 242/54 A 3,434,255 3/1969 Rabenhorst 242/54 A X 3,434,254 3/1969 Robin 242/54 A X FOREIGN PATENTS OR APPLICATIONS 1,009,297 1 1/1965 Great Britain 52/108 Primary Examiner-John W. I-Iuckert Assistant Examiner-Milton S. Gerstein [5 7] ABSTRACT A collapsible tubular extendable structure comprising four walls wherein two-oppositely disposed walls are formed by a pair of elongated ribbons, all of which are joined along their longitudinal edges forming a plurality of cusps allowing the structure to be folded flat and wound into a coil having the width thereof approximately equal to the diameter of the structure in an extendable mode. Four of the cusps are provided with means to permit positive control when the structure is being extended.
12 Claims, 4 Drawing Figures TUBULAR EXTENDABLE STRUCTURE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an extendable structure and more particularly to an extendable tubular structure capable of being collapsibly folded when wound or rolled onto a spool for storage but becoming relatively rigid when extended in an operating mode.
2. Description of Prior Art Tubular extendable structures, i.e. elements which are formed by sheet material wound on a drum and which assume a tubular shape when unrolled, are well known in the art. Several types of such structures are, for example, disclosed in US. Pat. Nos. 2,905,282, 3,168,263, 3,504,164, and 3,528,543.
Many problems still exist in design of such extendable structures. For example, one problem is a long play length, i.e. the length of material off the drum be fore the tube is formed which gives rise to torsional instability of the structure due to the open section of the partially formed tube adjacent the drum prior to the complete formationof the tube. This then gives rise to another problem which is the relatively large amount of power required to wind and unwind the structure.
SUMMARY OF THE INVENTION The invention as herein disclosed provides a novel collapsible, and extendable structure, that when deployed in an extended operating mode unfolds and forms a somewhat substantially tubular attitude. This structure comprises a plurality of elongated flexible sheets or ribbons which are so arranged as to be folded in a flattened position at which time the structure is capable of being rolled or wound about a spool or drum. There is provided six sheets of resilient material wherein two oppositely disposed single sheets form upper and lower walls respectively, and wherein each oppositely disposed side wall is fonned by a pair of narrow elongated resilient sheets. The pair of narrow sheets are fixedly attached by inwardly formed cusps. Hence the outer edges of each narrow ribbon or sheet is respectively secured to the corresponding edges of the single strip walls, thereby fonning outwardly projecting cusps therebetween. Thus, the configuration of the tubular structure includes four outwardly extended cusps and two inwardly projecting cusps. When the tubular structure is collapsed and folded flat, the two single walls become means by which the structure is capable of being wound about the drum, the width of each wall thereof being approximately equal to the diameter of the expanded tubular structure.
Further, when the structure is to be displaced to an operating mode, there is provided a drive means for engaging the outwardly extending cusp whereby the structure is unrolled and allowed to expand to a well defined tubular structure. Due to the inherent resilient materials, such as various thin metal foils of aluminum, and steel or non-metallic composites such as graphiteepoxy, or glass-epoxy, the expanding process takes place through its own stored energy. Thus, the application of a particular material will be determined generally by the intended use to which the structure is to be adapted. It therefore can be seen that when the fully expanded structure is deployed the longitudinal cusps add strength, stiffness and stability along the entire length of the extended structure which has been heretofore unobtainable.
OBJECTS OF THE INVENTION An object of this invention is to provide an improved tubular extendable structure.
Another object of this invention is to provide a thin wall tubular structure having a plurality of longitudinal cusps that allow the structure to fold or wind onto a drum or a spool wherein the folded structure has a width that is substantially no more than the diameter of the extended structure.
Another object of this invention is to provide a tubular extendable structure with improved anchoring, torsional resistance and extendable features.
Still another object of the present invention is to provide an extendable tubular structure of this character that is flexible, and resilient, but yet capable of having sufficient strength and stiffness along the entire body of the structure when deployed in an operating mode.
These and other objects will become more apparent after studying the following description of the preferred embodiment of the invention together with the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE DRAWINGS Referring now to the drawings and more particularly to FIG. 1, wherein there is schematically shown a novel tubular extendable structure generally indicated at 10,
being paid off a spool or drum (not shown) that would be located concentric with a coiled flat portion 11 of the structure. As the flat portion of the structure is unwound from said drum it will expand as at 12, forming a substantially four-sided tubular structure comprising six ribbons or sheets of thin flexible material, wherein said material may consist of many various metallic materials having a somewhat resilient quality such as aluminum and steel foil or of non-metallic composite materials of graphite-epoxy or glass-epoxy.
The construction of the tubular structure as shown in FIG. 2 comprises an upper wall 14 of a single elongated flexible sheet and an oppositely disposed lower wall 17 which is also formed of a single elongated flexible sheet. Both walls are interconnected through side walls each of which are made up of two elongated sheets, the first side wall having sheets 15 and 16 and the second having sheets 18 and 19. Each of the six sheets are joined one to the other by six cusp welds forming cusps or mating edge. Thus, the substantially tubular structure is formed by the mating one edge of wall 14 to one edge of sheet 15 thereby providing an outwardly extending cusp 21. Sheet 15 is then joined along its opposite ege to one edge of the adjacent sheet 16 thereby forming an inwardly extending cusp 22 leaving the opposite end free to be secured to one edge of wall 17 forming another outwardly extending cusp 23. The opposite edge of wall 17 is then secured together with one edge of sheet 18 providing a third outwardly extending cusp 24. A second inwardly extending cusp 25 is created along the inner edges of both sheets 18 and 19 respectively with the outer edge of sheet 19 secured to one edge of wall 14 forming the fourth outwardly extending cusp 26 thereby completing the structural .arrangement of a collapsible tube. It should be noted here that the width of sheets 15, 16, 18 and 19 are each substantially half of the width of wall 14 and 17. Therefore, when sheets 15 and 16, and sheets 18 and 19 are respectively secured together, they form an individual wall acquiring the overall substantial width of walls 14 and 17.
Thus, the two oppositely disposed cusps 22 and 25 are directed inward while the other four cusps 21, 23, 24 and 26 are directed outwardly and are substantially spaced about 90 apart. These four cusps could be spaced as much as 100 apart and as little as 80 apart. Since there are four cusps that are about 90? apart, the width of the ribbons or walls 14 and 17 is approximately or substantially equal to the diameter of the tubular structure when unrestrained or when the structure assumes the configuration shown in FIG. 2.
Referring again to FIG. 1, the means are shown that improve the anchoring, torsional resisting and extendable features of the structure. The means preferably includes uniformly spaced perforations or holes 31 formed in the four external cusps 21, 23, 24 and 26. The holes on each one of the cusps engage a toothed means 32. Each of the toothed means 32 is preferably shown as a toothed belt 33 mounted on two suitably spaced sprockets 34 and 35 so that more than one tooth on the belt engaged the holes on a respective cusp to increase the resistance to axial forces. The structure being made of thin ribbons inherently has minimum bearing strength within the holes. The four spaced means 32 inherently increase the bending moment strength of the structure. To drive the' means 32, four sprockets 34 on the respective means are mounted on respective shafts 41 and 42 (two on a shaft) which are in turn coupled to a drive means 43 so that all four sprockets rotate at the same speed. The structure would be obviously enclosed in a suitable housing as depicted by the dash lines and would include the usual features for controlling the transition geometry of the tubular structure from extended to flatten, for supporting and enclosing the drive unit bearings, drive motor, shafts and gears, and for supporting and enclosing the spool for the coil portion 11. However, the means as described and shown in FIG. 1 is for illustrative purposes and it is contemplated that other various means can be incorporated depending on the requirements placed upon the structure such as in its use and installation.
Although the preferred embodiment of the invention has been shown and described, one skilled in the art after reading this disclosure could modify the preferred embodiment without departing from the scope of the invention as defined in the claims. Therefore the invention is understood to be limited by the appended claims.
What is claimed is:
1. A collapsible tubular extendable structure to be stored in a coiled manner comprising:
a first pair of oppositely disposed elongated walls,
each wall being preformed to expand along the longitudinal axis of said tubular structure when unrestrained from a flattened condition. and capable of being rolled into a coil about an axis generally transverse to its longitudinal axis in a substantially flattened condition; and
a second pair of oppositely disposed elongated walls having their respective longitudinal edges bonded to respective adjacent longitudinal edges of said first pair of walls to form said tubular structure, each of said second walls being preformed to expand transversely when unrestrained and each wall being capable of folding to a flattened condition contiguous to said first pair of walls when said structure is rolled into said coil.
2. The structure of claim 1 wherein:
said first pair of walls have a width that is substantially equal to the diameter of the unrestrained structure;
said second pair of walls each having two ribbon elements bonded together along one of their longitudinal edges to form a cusp that is directed inwardly of the structure.
3. The structure of claim 2 wherein: said ribbon elements of said second pair of walls are substantially half as wide as each of said first pair of walls.
4. The structure of claim 1 wherein:
said first pair of walls and said second pair of walls are all joined one to another to form a plurality of cusps disposed substantially apart and directed outwardly.
5. The structure of claim 3 wherein:
means are provided to engage each of said outwardly directed cusps to provide longitudinal motion to said structure.
6. The structure of claim 5 wherein said outwardly directed cusps are provided with evenly spaced holes formed in each cusp and said means comprises:
a drive means engaging the holes of respective cusps; and motor means for driving each of said drive means in unison.
7. The structure of claim 6 wherein:
each of said drive means comprises:
a toothed belt having a plurality of teeth;
a pair of pulleys over which said belt rides so that more than one tooth and more than one hole are in engagement;
and means for coupling said motor means to one of said pulleys.
8. The structure of claim 1 wherein:
all of said walls are formed of a metallic flexible material.
9. The structure of claim 8 wherein:
said metallic flexible material comprises an aluminum foil.
10. The structure of claim 1 wherein:
all of said walls are formed of a non-metallic composite material.
11. The structure of claim 10 wherein:
said non-metallic composite material comprises a graphite-epoxy composite.
12. The structure of claim 10 wherein:
said non-metallic composite material comprises a glass-epoxy composite.