US3664069A - Pneumatic shell structures constructed from synthetic resin films - Google Patents

Abstract

Disclosed herein is a pneumatic shell structure which is constructed from two sheet layers, each composed of a plurality of long rectangular synthetic resin films which are arranged side by side in a manner that longitudinal side edge portions of the films are mutually superimposed. The sheet layers are hermetically sealed about their edges to a support frame, so that the arranged films can uniformly carry the stress created on the sheet layers owing to the inner pressure of the airtight air chamber.

Description

United States Patent Ikaiet a1.

[54] PNEUMATIC SHELL STRUCTURES CONSTRUCTED FROM SYNTHETIC RESIN FILMS [72] Inventors: Masai-u Ikai, Kyoto-shi; Toshikazu Ishii,

Otsu-shi; Michiaki Higashikuze, Takatsuki-shi, all of Japan [73] Assignee: Toray Industries, Inc., Tokyo, Japan [22] Filed: July 18, 1969 [21] Appl. No.: 843,068

[30] Foreign Application Priority Data July 25, 1968 Japan ..43/52711 Aug. 1, 1968 Japan.... ....43/54264 Dec. 26, 1968 Japan... ....43/95110 2,398,886 4/1946 Drake et a1.

[451 May 23, 1972 2,425,060 8/ 1947 Gildehaus ..52/ 200 3,122,985 3/1964 Osborne ..52/2 3,127,699 4/1964 Wasserman... 52/200 X 3,176,982 4/1965 ODaniell... ..52/2 X 3,298,142 l/1967 Isaac ..52/2 3,307,309 3/ l 967 Bloxsom ..52/200 3,444,033 5/1969 King 161/39 X 3,455,073 7/ 1969 Kiekhaefer ..52/ 200 3,481,087 12/1969 Stafford ..52/2 2,610,936 9/1952 Carlson... 161/109 X 3,300,927 1/ 1967 Bettoli ..52/622 X 3,421,977 1/1969 Hutchinson et a1 ..52/622 X FOREIGN PATENTS OR APPLICATIONS 1,273,271 8/1961 France ..52/200 Primary Examiner-Price O. Faw, Jr. Attorney-Robert E. Burns and Emmanuel J. Lobato 57 ABSTRACT Disclosed herein is a pneumatic shell structure which is constructed from two sheet layers, each composed of a plurality of long rectangular synthetic resin films which are arranged side by side in a manner that longitudinal side edge portions of the films are mutually superimposed. The sheet layers are hermetically sealed about their edges to a support frame, so that the arranged films can uniformly carry the stress created on the sheet layers owing to the inner pressure of the airtight air chamber.

19 Claims, 3 1 Drawing Figures Patented May 23, 1972 3,664,069

8 Sheets-Sheet .1

2 ,1 wil Pa tented May 23, 1972 8 Sheets-Sheet 2 Patented May 23, 1972 3,664,069

8 Sheets-Sheet 5 Patented May 23, 1972 3,664,069

8 Sheets-Sheet 4.

Patented May 23, 197 2 8 Sheets-Sheet 5 Patented May 23, 1972 3,664,069

8 Sheets-Sheet 6 55 H 64 Hg /4 Patented May 23, 1972 3,664,069

8 Sheets-Sheet 7 TENSION FORCE (kg L Patented May 23, 1972 8 Sheets-Sheet a PNEUMATIC SHELL STRUCTURES CONSTRUCTED FROM SYNTHETIC RESIN FILMS The present invention relates to pneumatic shell structures constructed from synthetic resin films and a method for constructing the same.

It is well-known that such component structures for buildings such as tents, roofs or walls can be made of sheets of synthetic resins such as polyethylene terephthalate, polyacrylonitrile, polystylene, polyethylene, polypropylene, polyamide or polyvinylchloride, or woven fabrics, knitted fabrics, non-woven fabrics or nets coated with such coating synthetic resins as polyvinylchloride, chlorosulfonated polyethylene, chloroprene rubber, butyl rubber or polyurethane.

It is also a kind of known art to construct shell structures utilizing airtight chambers formed by supplying air in between two or more airtight sheets. These types of structures are generally called pneumatic shell structures. This pneumatic shell structure can maintain its shape by retaining the stress created in the sheets forming the airtight chamber in a balanced relationship to the internal pressure of the gas contained in that airtight chamber. In the construction of such pneumatic shell structures, a woven fabric coated with such soft high polymeric compounds as vinyl chloride, chlorinated polyethylene or chlorinated rubber is mainly and conventionally used as a material sheet. In some cases, such a coated fabric may be further superimposed by other layers of net-like configuration.

On the other hand, also known is the forming of a balloon using mutually and suitably bonded films of synthetic resin such as polyethylene terephthalate. In this case, the balloon forming films are covered with one or more layers of net configuration and the stress created in the film is absorbed by the film covering net configuration.

In any of the above-illustrated prior arts, the sheet for forming the airtight chamber is prepared from a three-dimensionally bound films layer, by which the sheet is prevented from breaking due to the stress created in the sheet. In order to construct a structure of this nature and configuration, it was necessary to cut, sew and bind the component films in he three-dimensional shape. However, because such threedimensional preparation required very highly skilled techniques, there has been little penetration of pneumatic shell structures of this type, particularly large pneumatic shell structure, into actual utilization. Besides the conventional pneumatic shell structures of this type are fundamentally composed from a pair of sheets disposed in a face-to-face relationship. There was a limitation to the scale of the structure owing to a limitation to the strength of the component sheets.

Further, in the conventional pneumatic shell structure, peripheral inner edge portions of the sheets which constructs the structure have to be fixedly bound using metal fasteners for obtaining an airtight internal condition of the structure. The metal fasteners of this kind are apt to rust by contact with water such as rain and it causes undesirable leakage of water into the structure through the rusted portions. Such water is frozen by the lowering of the surrounding temperature, especially in winter season, to form a bar in uniform distribution of the stress created in the sheets or to contaminate the films surface.

When the inner edge portions of the sheets are bound together using such fastening devices, such as fastening bolts, the difference in elastic modulus, thermal expansion coefficient or creep property against an external force between the sheet and the fastening device often causes undesirable concentration of a shearing force upon the fastened portion resulting in accidental breakage of those portions.

In case the constructed pneumatic shell structure is provided with corner portions, water is liable to get into the structure through the comer portions and a considerably complicated and highly skilled technique is required for preventing such undesirable water leakage.

Still other drawbacks of the pneumatic shell structure of the conventional type is found in the fact that the component sheets are not so durable against exposure to sun-light.

A principal object of the present invention is to provide a pneumatic shell structure of relatively simple construction wherein stress caused by the pressure of the internal gas can be distributed uniformly in the sheets composing the structure and a method for constructing such a structure in a relatively simple manner.

Another object of the present invention is to provide a pneumatic shell structure wherein water leakage through peripheral inner edge portions of the component sheets is completely prevented.

Still another object of the present invention is to provide a pneumatic shell structure having corner portions resistant against water leakage therethrough.

A further object of the present invention is to provide a pneumatic shell structure durable against attack by sun-light and other weather conditions.

In order to attain the above-described several objects, the pneumatic shell structure of the present invention comprises a pair of sheet layers, an upper sheet layer and a lower sheet layer, arranged in a face-to-face relationship and forming an airtight chamber therebetween. Each of the upper and lower layers comprises an airtight inside layer forming the airtight chamber, an outside layer facing outside, and one or more intermediate layers inserted between the airtight inner layer and the outside layer for carrying most of the stress created on the sheet layer. This intermediate layer is prepared from a plurality of synthetic resin films having a relatively long rectangular profile, in other words, a belt-like shape, and smooth surfaces. The long rectangular films are arranged in a side-by-side relationship in which long side edge portions of adjacent films are superimposed to each other without adhesion.

The thickness of the film usable for composing the shell structure of the present invention should preferably be 0.5 mm or thinner and the initial tensile elasticity should be at least 4 X [0 kglcm or more favorably be at least 2 X 10 kglcm Films made of polyethylene terephthalate, polyethylene, polypropylene, polyvinyl chloride, polycarbonate or ethylenevinylacetate copolymer can be advantageously used for the purpose of the present invention. Among the abovedescribed polymers, polyethylene terephthalate or hard polyvinyl chloride are used with best results. Such synthetic I resin films may be sputtered with aluminum or copper layer on at least one of their surfaces in a manner of vacuum evaporation.

Dimensions and shape of the film are to be selected suitably in accordance with the dimensions and shape of the shell structure to be constructed. Generally for the practical utilization of the act of the present invention, a long belt-like film which is wound into a roll-form is suitable. The relationship between the unit length and unit width of such a belt-like film is dependent upon the desired curvature of the pneumatic shell structure. Practically, in case the tangent, or rise, of the structures curvature is one-tenth, the films width should preferably be in a range from one-tenth to one-fifth of the film's length.

Construction of the shell structure from the component films is carried out by forming respective layers on a mold table having a curved surface corresponding to the desired curvature of the pneumatic shell structure. For example, in constructing the upper sheet layer of the shell structure, an inside layer is firstly formed on the curved mold table. This inside layer may be composed of either a single film sheet or a sheet composed of a plurality of belt-like films airtightly adhered or sealed to each other at their contacting side edge portions by a suitable adhesive, adhering tape or grease. Secondly, a needed number of synthetic resin films are arranged on the airtight inside layer in a parallel arrangement in which their side edges are superimposed mutually but not adhered. Thus arranged films form an intermediate layer for carrying most of the stress created in the shell structure sheet. In case two or more of the arranged film layers are piled up for constructing an intermediate layer, each arranged films layer is superimposed on another in a manner in which the longitudinal direction of the films in the respective layers should be in a perpendicularly crossed condition.

Thirdly, after the completion of the arrangement of the intermediate layer or layers, the outside layer is formed thereon. This outside layer may be composed of either a single film airtight sheet or a sheet composed of a plurality of belt-like films superimposed on each other at their side inner edge portions, and, if desired, adhered airtightly the superimposed portions by a suitable adhesive or adhering tape. In order to protect the shell structure sheet layer from undesirable influences of sunlight, the outside layer may be composed of synthetic resin films subjected to a suitable treatment for bestowing ultraviolet ray absorption property or heat reflection property.

Further features and advantages of the present invention will be apparent from the ensuing description, reference being made to the accompanying drawings showing preferred embodiments wherein;

FIG. 1A is a plan view of a model of the pneumatic shell structure of the present invention;

FIG. 1B is a cross section taken along a line BB in FIG. 1A;

FIG. 1C is a side cross sectional view for showing a layered arrangement of films composing the pneumatic shell structure shown in FIG. 1A;

FIG. 2A is a perspective representation of a reinforcement usable for the pneumatic shell structure of the present inventron;

FIG. 2B is a side cross section of the reinforcement shown in FIG. 2A;

FIG. 2C is an explanatory drawing for showing a reinforcing mechanism of the reinforcement shown in FIG. 2A;

FIG. 3A is a cross sectional representation for showing the attachment of the reinforcement shown in FIG. 2A onto an inside wall surface of an airtight chamber of pneumatic shell structure of the present invention;

FIG. 3B is an explanatory side view of the inflated pneumatic shell structure of the present invention provided with the reinforcement shown in FIG. 2A;

FIG. 4A is a cross section of a model of the pneumatic shell structure composed of a plurality of film layers;

FIG. 4B is a graphical diagram showing a pressure distribution in the shell structure as shown in FIG. 4A;

FIG. 5A is a cross section of a model of the pneumatic shell structure containing an air layer between the film layers;

FIG. 5B is a graphical diagram showing a pressure distribution in the pneumatic shell structure as shown in FIG. 5A;

FIGS. 6 and 7 are cross sectional representations of some examples of a ventilating means usable in combination with the pneumatic shell structure of the present invention, respectivcly;

FIGS. 8 and 9 are cross sectional side views of some examples of the conventional devices for fastening the peripheral edge portion of the sheet layer of the pneumatic shell structure onto a supporting member;

FIGS. 10 to 17 are cross sectional side views of several embodiments of sealing means usable for the pneumatic shell structure of the present invention;

FIG. 18 is a graphical diagram for showing a covering effect of a metallic surface of the supporting member with various covering paint layer according to the present invention;

FIG. 19 is an explanatory drawing for showing comer parts of the pneumatic shell structure of the present invention,

FIG. 20 is a perspective view of the comer part of the pneumatic shell structure of the present invention having a cut-off;

FIG. 21A is an enlarged perspective view of the cut-off corner part of the pneumatic shell structure;

FIG. 21B is a perspective view of a corner sealing member adapted for being attached to the cut-ofi corner shown in FIG. 21A;

FIGS. 21C and 21D show a manner of fixing the comer sealing member shown in FIG. 218 to the cut-off comer part;

Referring to FIG. 1A, a model configuration of the pneumatic shell structure of the present invention is illustrated. As shown in the drawing, the shell structure 1 comprises a layered sheet part 2 and a fastener part 3 for providing a seal around the edges of the sheet part 2. As is shown in FIG. 1B, the sheet part 2 comprises an upper sheet layer 4, a lower sheet layer 5, and an airtight chamber 6 disposed between the two layers 4 and 5. The fastener part 3 seals the peripheral edge portion of the layers 4 and 5 together into an airtight condition. Upon supplying air into the airtight chamber 6 formed in between the tightly connected layers 4 and 5, both layers 4 and 5 are inflated outwardly in an arc form, by which the shell structure I having curved surfaces is formed. The configuration of the sheets layers 4 and 5 is shown in FIG. 1C, wherein the upper sheet layer 4 comprises several component layers including an outside layer 7a; intermediate layers 8a, 8b and 8c and 9a and 9b and an inside layer 10a, arranged in a superimposed condition. In the case of the lower sheet layer 5, the component layers are superimposed also, but in reverse order and include only three intermediate layers 84', 8e and 9c, enclosed by an inner layer 10b and an outer layer 7b.

As is shown in the drawings, each component layer comprises a plurality of strips of synthetic resin films arranged in a manner in which the films are disposed in a substantially parallel condition, and in which each strip is shifted transversely in the same direction from the preceding strip so that the longitudinal side edges of one strip overlap the said edges of each preceding and succeeding strip.

When the longitudinal direction of the films in a componental layer, for example layer in FIG. 1C, is laid in the X direction in FIG. 1A, the longitudinal directions of the films in the adjacent component layers, for example layers 7a and 9a are laid in the Y direction which crosses perpendicularly with the X direction.

That is, in FIG. 1C, the films in the outer layer 7a run in the Y direction, the films in the intermediate component layers 80, 8b and 80 run in the X direction, the films in the intermediate component layers 9a and 9b run in the Y direction, and the films in the inside layer 10a run in the Y direction. In such a construction, the overlapping portions 1 l of the films in the outer layer 70 are hermetically fixed together by a suitable fixing means such as an adhesive or adhering tape for preventing the shell structure from penetration of water. However, where the shell structure 1 is intended only for indoor use, the overlapping portions in the outer layer 7a do not always require such fixing. The overlapping portions of films in the inside layer 10a, however, must be hermetically sealed together by a suitable adhesive, adhering tape or grease for maintaining the inner chamber 6 in an airtight condition for both indoor and outdoor use. The overlapping portions of films in the componental layers 8a, 8b, 80, 9a and 9b of the intermediate layer are not fixed.

When air is supplied into the airtight chamber 6 of the shell structure 1 of the above-described configuration, the internal pressure caused by the filled air balances itself with stress created in the sheet layers and the created stress is uniformly distributed in the films composing the sheet layers. Because the films composing the intermediate component layers are not adhered to each other as described above, they can perform a suitable relative displacement in accordance with the internal pressure of the air resulting in a formation of a smooth curvature. Owing to this free relative displacement of the component films most of the stress caused by the internal pressure applied to the sheet layers can be distributed uniformly in the intermediate components layers.

By employing the above-described art of the present invention, any desired curvature can be obtained from flat films in a simple manner and some of the adhering operations can be omitted resulting in a considerable simplification in the pneumatic shell structure construction.

In order to retain the shape of the pneumatic shell structure thus constructed, reinforcing means are further proposed in the art of the present invention as is hereinafter disclosed.

Referring to FIGS. 2A, 2B and 2C, an embodiment of such reinforcing means is shown. In the shown embodiment, a reinforcement l3, composed of an elastic synthetic resin film, includes a bonding surface 14 and a reinforcing body 16 connected to the bonding surface 14 at a bent edge in a bendable relationship. The bonding surface 14 is adapted for attachment to an inside wall surface of the airtight chamber 6 as shown in FIG. 3A, and under this condition, when the air is filled into the airtight chamber 6 and the sheet layers are expanded toward the outside and provided with curvatures of a desired nature, the bonding surface 14 is expanded and converted into a curved surface 140 following the curvature formation of the sheet layers and the bent edge 15 is also stretched and converted into a curved edge 15a as shown with a dotted line in FIG. 2C. With this stretch of the bent edge 15 into the curved edge 15a, the reinforcing body 16 is paced into a bent relationship to the curved surface 14a approximately with a right angle as shown by a dotted line and designated with a reference numeral 16a in FIG. 2C. Then, as is shown in FIG. 3B, the reinforcing body 16 now in the 160 position extends from one sheet layer to another through the airtight chamber 6 so as to support the two layers in a given configurational relationship. Further reinforcing effect can be obtained if two reinforcements 13 are disposed in a closely contacting arrangement as shown in FIG. 3B. For easy movement of the reinforcing body 16 of reinforcement 13, one or more apertures may be formed through the reinforcing body 16.

For better shape retention of the shell structure in an inflated condition, the present invention is further provided with the following improvement. In the shell structure configurational mechanism of the present invention, each sheet layer is composed of a plurality of layered films, the internal pressure caused by the air supplied into the airtight chamber is absorbed by the componental films by which the shape of the shell structure is retained as desired.

For example, if a sheet layer is composed of four film layers 21 to 24 superimposed mutually in close contact as shown in FIG. 4A, an internal pressure a of the airtight chamber 6 is uniformly distributed into the four film layers and absorbed therein as shown in FIG. 4B. In case an air layer exists between the film layers 23 and 24, as shown in FIG. 5A, the film layers 21 to 23 absorbs only a part c of the pressure a and the film layer 24 should be for absorbing the remaining part b (b =a c) as shown in FIG. 5B. That is, the stress caused by the internal pressure is distributed non-uniformly into the componental layers composing the sheet layer. In order to eliminate this non-uniformity in the stress distribution, it is necessary to discharge the air contained within the space of the sheet layer so as to obtain a closely contacting arrangement of the componental layers composing the sheet layer. In this connection, however, the pneumatic shell structure of the present invention is advantageous in the configuration of the sheet layer wherein, only the inside layer is hermetically formed and the remaining outside and intermediate layers are respectively composed of belt-like films superimposed mutually at their side edge portion without any adhering, that is, the remaining layers are formed as air permeable. But, when the shell structure is purposed for use out-doors, the outside layers should be hermetically formed so as to prevent unfavorable seepage of water and/or fine particles of dust. In this case, the shell structure needs a particular means for ventilating the air contained within the sheet layer part.

Some examples of such a ventilating means are illustrated in FIGS. 6 and 7. In the example shown in FIG. 6, a superimposed portion 26 of the outside layer 24 is provided with an air pipe 27 having an outlet 29 directed downwards. In the example shown in FIG. 7, the fastened portion of the sheet layer is also provided with an air pipe 27 inserted in between the outside layer 24 and the intermediate layer 23. This air pipe 27 is provided with a valve 28 for preventing counterflow as shown in FIG. 6. So, only air contained inside can be discharged into the atmosphere therethrough, but external water or air can not get inside passing therethrough. By completely discharging air contained within the sheet layers utilizing the abovedescribed ventilating means, all the componental film layers composing the sheet layer can be brought into a complete contact and the stress caused by the internal pressure can be distributed uniformly into respective componental film layers.

Peripheral edge portions of the pneumatic shell structure must be sealed to affect watertightness using suitable metallic fastening devices. It is well-known that water tends to get inside the sheet layer passing through the fastened portions and thus invaded water causes rusting of the metallic fastening devices. Further, the invaded water has a tendency to become frozen by the lowering of the surrounding temperature resulting in non-uniform distribution of stress respective componental flm layers. In order to eliminate this troublesome water invasion, the art of the present invention includes provision of novel sealing means usable for the pneumatic shell structure.

Referring to FIGS. 8 and 9, some examples of the fastening device of the conventional type are shown. In the example shown in FIG. 8, the edge portions of the upper sheet layer 4 and the lower sheet layer 5 is sandwiched by a supporting member 31 and a fastening member 32 and watertightly sealed by a fastening bolt 33. However, in this construction, outside water can easily get inside the sealed part following along the surface of the fastening bolt 33, and the crevices spaced between the fastening member and the sheet layer. In the example shown in FIG. 9, the edge portion of the sheet layers is curved along the peripheral surface of the supporting member 31a and is fastened by the fastening bolt 33 plated to the supporting member 31a being sandwiched by the supporting member 31a and a fastening member 32a. Also in this case, outside water gets inside following along the surface of the fastening bolt 33 and the crevices spaced between the fastening member 32a and the sheet layer. Several methods for overcoming the abovedescribed drawbacks possessed by the conventional fastening device are shown in FIGS. 10 to 17.

In the embodiment shown in FIG. 10, a bottom member 35 of the sealing means is disposed to the supporting member 31a in a manner shown in the drawing. An end 38 of a top member 37 of the sealing means is watertightly adhered by a adhesive layer 41 to an outside surface of the sheet layer 2; where as another end 39 of the top member is watertightly fixed by a fixing member 40 to one end 36 of the bottom member 35. An additional film 42 is disposed covering the adhered end 38 of the top member 37 for a further complete sealing effect. If the sheet layer 2 performs slight displacements upon receipt of x or y-directional tension, the top member 37 can follow the displacement easily. Thus, the metallic fastening bolt 33 can be completely protected by the bottom member 35 and the top member 37. The top member is made of a watertight sheet such as synthetic resin film.

In case of the embodiment shown in FIG. 11, a covering member 43 covers the fastening bolt 33, fastening nut 34 and the fastening member 32a and both ends 44 and 45 of the covering member 43 adhere to the outside surface of the sheet layer 2 and the supporting member 31a, respectively, by waterproof layers 46 of an adhesive such as silicone resin adhesive. One end 38 of the top member 37 watertightly adheres to the outside surface of the sheet layer 2 by a suitable adhesive layer and also the other end 39 thereof is watertightly fixed to one end 36a of the supporting member 31a by the fixing member 40. The covering member 43 is made of a synthetic resinous material. By employing the abovedescribed sealing means, the fastened part of the shell structure can be completely protected from invasion by water.

In the embodiments shown in FIGS. 12 and 13, the fastening member 32 is provided with a recess 49 formed in an upper end 52 thereof. This end 52 is also provided with an annular recess 50 encircling the fastening bolt 33. The recess 49 is filled with suitable packings 47a. A covering plate 51 is connected to a lower end 53 of the fastening member 32 extending towards the supporting member 31 and a packing 47c is inserted in between the end of the sheet layer 2 and the covering plate 51. The annular recess 50 is provided with an annular packing 47b of an elastic nature, the inside peripheral surface of the annular packing 47b is put in close contact with the periphery of the fastening bolt 33 and the outside peripheral surface thereof is in close contact with the annular recess 50. Suitably selected elastic material may be used for the annular packing 47b in conformity to the requirement of the end use.

Referring to FIGS. 14 and 15, an embodiment of the sealing means includes an encircling member 54 disposed on the fastening member 32 and encircling the fastening bolt 33 and the nut 34 and a suitable sealing material 55 is filled inside the encircling member 54. Elastic sealants and oil coating materials are useful for this purpose. By disposing such a sealing member, invasion of water into the membraneous layer structure following the fastening bolt can be completely obviated.

FIG. 16 shows another embodiment of the sealing means including a suitable sealing paint layer 55a painted covering the fastening means and the sealing means. The sealing paint can be selected from acrylic polymer resin, polyvinyl chloride resin, polyurethane resin and epoxy resin paints according to the requirement in the end use.

The embodiment shown in FIG. 17 comprises two recesses 49 and 56 formed in the upper and lower ends 52 and 53 of the fastening member 32. Together with these, an annular recess 50 is also formed encircling the fastening bolt 33. In combination with this mechanical construction, the supporting member 31 is provided with a recess 56a formed in one end 57 thereof and an annular recess 50a encircling the fastening bolt 33. As is shown in the drawing, the recess 49 is provided with an elastic packing 58 inserted watertightly therein and the recesses 56 and 56a receive respective ends of a packing 59 for covering the end of the sheet layer 2. Elastic packings 60 and 61 are inserted into the recess 50 of the fastening member 32 and the recess 50a of the supporting member 31. Any kind of elastic packing material selected from polyvinyl chloride resin, polyolefine resin, rubber packing, etc., can be used for this purpose in accordance with the requirement of the end use. The sealing means of the above-described type can prevent the accidental seepage of water into the shell structure.

The art of the present invention is provided with a means for protecting the sheet layers fastened between the metallic supporting member and the metallic fastening member. Comparing the physical properties of the synthetic resin film for composing the sheet layer of the present invention with these of metallic material of the supporting member or the fastening member, the former has a smaller elasticity, larger thermal expansion and larger creepness than these of the latter, respectively. Thus, in case the sheet layer immediately contacted the metallic supporting member or the metallic fastening member, there was a breaking of the sheet layer due to concentration of stress. It was found that such disadvantages can be overcome by insertion of packing sheets having a tensile elasticity of at least 20,000 kglcm respectively, between the metallic supporting member and the sheet layer, and/or the metallic fastening member and the sheet layer. Packing sheet having a tensile elasticity smaller than 20,000 kg/cm such as vulcanized rubber sheet, foamed polyurethane sheet impregnating with asphalt, and soft polyvinyl chloride sheet has a tendency of deformation by tensile stress due to fastening action, thus, it is difficult that the sheet layer is always uniformly fastened by the above-mentioned low elasticity packing sheet. As the packing sheet for the fastening means, according to the present invention is useful, a packing sheet having a tensile elasticity of at least 20,000 kg/cm such as phenol resin, melamine resin, silicon resin, polyester resin, epoxy resin, styrol resin, styren-acrylonitrile copolymer resin, polymethyl methacrylate resin, polyolefine resin, polyamide resin, polycarbonate resin sheet.

Reinforced packing sheets which contains reinforcing fiber such as fiber glass may be used advantageously for the purpose mentioned above.

The edge portions, in other words, the peripheral end portions, of the sheet layer is maintained in a present shape by a metallic supporting member. In order to prevent the occurrence of metal rusting and to realize a uniform transmission of the stress from the sheet layer to the metallic supporting member by increasing a frictional force between the two, it is desirable to cover the metallic surface with a paint layer having a pencil hardness of degree F or higher and Sward Riickers hardness value, of at leastZS. apaint forpresent- TABLE 1.-HARDNESS 0F PAINT MEMBRANE Sword Pencil Riicker's Hardness hardness hardness Paint membrane:

A, 011 paint--- B 25 B, epoxy esterz- H 30 Sixteen sheets of polyethylene terephthalate films of 250 thickness, 88 cm width and 30 cm length were superimposed together. Both terminations of mm length of the superimposed films were gripped between the two steel plates and fastened with a bolt passing through holes formed through the middle portion of the steel plates. The fastening force was of 5.95 tons/single bolt when measured by a torque meter and converted into a corresponding shaft force. Thus prepared specimen was subjected to tensile elongating at an elongation rate of 5 mm/min on a tensile tester (type IS 5,000 which is obtained from Shimazu Seisakusho, Japan), the relation between the tensile force and the displacement of the gripped termination of the superimposed film sheets was observed and the result is shown in FIG. 18. In the drawing, the curve A is for the oil paint membrane case, the curve B for the epoxy ester membrane case and the curve C is for no paint case. It is apparent from this shown result that the termination displace ment is minimum in case the epoxide ester layer is formed. This means that the frictional force in between the painted steel surface and the film surface is considerably large in case of this specimen.

Next, a method for preventing water seeping into the pneumatic shell structure through comer parts thereof will be explained.

The sheet layers of a pneumatic shell structure are always placed under a stressed condition because of the internal pressure due to air contained in the airtight chamber. This stressed condition is variable following the variation of the internal pressure and the corner parts are liable to be accompanied with creases made thereon due to the variation in the stressed condition. Such crease formation often causes accidental seeping of water into the shell structure. In order to eliminate this trouble, the present invention provides the following corner part sealing system.

As is shown in FIG. 19, the corner part of a pneumatic shell structure is classified into a projecting corner 71 and a receding corner 72. In the ensuing description, a sealing system for the comer of the former type will be explained as an example. Referring to FIG. 20, in fixing the sheet layer 2 composed of the upper sheet layer 4 and lower sheet layer 5 on the supporting member 31, a corner part of the sheet layer superimposed on the corner part 71 is previously cut off as is shown in FIG. 21A. Aside from this, a corner sealing member 73 having a configuration as shown in FIG. 21B is previously prepared. Generally, the corner sealing member 73 is made of a synthetic resin film the same as that used for making the sheet layer 4. However, it can be made of other materials such as metal plate, plastic plate or reinforced plastic plate containing glass fibers. After preparation of the comer sealing member 73, it is placed on the lower sheet layer and is adhered thereon by an adhesive layer 74 in a watertight condition as shown in FIG. 21C. Next, the upper sheet layer 4 is placed on thus adhered corner sealing member 73 and is adhered tetrahydroxybenzophenone, 2-hydroxy-4,4'-dimethoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4- methoxybenzophenone, 2,2-dihydroxybenzophenone, 2,2- dihydroxy-4,4-diethoxybenzophenone, and 2-hydroxy-4-octhereon by an adhesive layer 75 in a watertight condition as 5 toxybenzophenone, and triazols such as O-hydroxyphenyl shown n HQ Z Thus, the Corner Parts Of the Pheumatle triazol. For the purpose of protecting the shell structure from h ll Structure Can be Provided With complete watertight P undesirable influences of heat, it is recommended to cover the p y together With refihed appearance when the Pneumatic synthetic resin film especially polyethylene terephthalate film, shell structure of the present invention is adapted for out-door i h a metal layer tt d b va uum eva oration which has it is subjected to xp to sun-light h n, h a thickness of m or thinner. This sputtered metal layer synt r n m c p ng h h l Structure are should be placed beneath the above-described ultraviolet ray degraded owing to heat and ultraviolet rays from the sun-light intercepting layer. If the thickness of the metallic layer exand the heat come in hrough the Sh layers r lting in ceeds 20 mp, it tends to undesirably intercept even the visible elevation of the internal temperature. In order to eliminate 15 light rays. Such kind of metals as aluminum, silver, zinc and these troubles, the art of the present invention proposes provio er can be used for this purpose in any of the known sion of a heat-insulation layer and/or an ultraviolet ray intervacuum evaporation manners. cepting layer to the outside layer or layers. It is already known By disposing the heat intercepting layer of this nature that a resistance ofthe layer against weather conditions can be together with the u t a o et ray intercepting layer onto the enhanced by mixing or coating a suitable ultraviolet ray absor- 2O outermost Ponioh of the Sheet y n y the Visible light can bent to the synthetic resin film in the manufacturing thereof. p through the layers Wlth effective ehmmauoh of l lln the conventional weather-resisting sheet layer, a weathertravlolet'rayS! near Infrared y and Infrared Y contained proofing film of a desired thickness or a plurality of superimthe suh'hght- I posed weather-proofing films are used for preparing the The Pheumauc h?" structlh'e the Present 'h desired thickness and the manufacturing cost thereof is very composed of belt'hke synthetlc reism films supenmposfad to expensive. Facing this trouble, a modified embodiment of the each other by a novel construcung by W h a pneumatic shell structure of the present invention comprises stlrongly consqgcted f g z i E be obtained m a an additional synthetic resin protector film covering the ordip W PP era y owere costs nary synthetic resin film layers. The thickness of the additional a we 6 3 l. A pneumatic shell structure comprising first and second protector film is 25 1, or th1nner and the protector is capable of sheet means of air and water impermeable materlal; means for absorbing and/or intercepting ultraviolet rays hav1ng a wave hermet1cally sealing said first and second sheet means length of 350 mp, or shorter. Polyethylene terephthalate film 1s h d h h h favorabl used for this u ose This 01 eth lene tere hthatoget er amun t penp enes to prov] e an almgt 1 fl y h f p p chamber between sa1d first and second sheet means; each said ate o SOT mg g gf g l sheet means including an outer layer, an airtight inner layer Wave eng 5 or S an y W t ls defining a portion of said airtight chamber, and an interdegraded' If Several Sheets 0 p9lyethy tereph mediate layer disposed between said inner and outer layers, films are exposed to ultravlolet rays a supenmposed f said intermediate layer comprising a plurality of first strips of only ofnermost film degraded by h ultravlolet synthetic resin film having longitudinal and transverse extents y and the Inside film Sheets are, to an appfeclable f f 40 defining major surfaces thereof, said strips being arranged in a prevented from degradation, by the rays. This protect1on 1s configuration wherein they are disposed in parallel and due f the Putermost ph y y threphthalatef film being cessively shifted in the direction of said transverse extents so Provlded W1th the fuhfmoh of absorblhg and/Or lhtel'cephhg that a longitudinal marginal surface portion of each said strip the uhfavlolet y hav1ng a wave length of 350 "h foverlaps a longitudinal marginal surface portion of the next Refemhg to Table wealher'proof of the Supenmposed succeeding strip and is unattached thereto along said longitu- OUS kinds of synthetic resin films are Showhdinal marginal surface portion; and support means connected TABLE .2

Exposed to sunlight Unexposed 6 months 12 months Tensile Breaking Tensile Breaking Tensile Breaking strength elongation strength elongation strength elongation Sprcillltn Film Lnyvr (kg/mm?) (percent) (kg/mm?) (percent) (kg/mm?) (percent) l'olyvinyl chloride 1 1 277 1.5 4 13s 0 n llllll of 351.1 thhk- I l. 7 (l 0 noss'. l L 1.6 1) (I ll. lolyntllylunn toropln l i227 l. U (l (l t) thnlntu Iilnl M251; 2 127 18.15 103 16. 4 .18 thickness. 1 I: 2131.1; {ill 2 n. 0 .1) 2 1n z 120 21. 4 121 20.1 116 3 126 21, s 123 20. 7 120 *Weatherproof polyethylene terephthalate Iil1n containing 0.3% of 2-l1ydroxy-4-oct0xybenzophenone.

As shown in Table 2, the degrading rate of the polyvinylchloride film specimen A is almost similar to the layers from 1 to 3 whereas, in case of the film specimen B, the degrading rates of the 2nd and 3rd layer is considerably smaller than that of the 1st layer. In the case of film specimen C, the 1st film layer contains an ultraviolet ray absorbant, 2-

to said hermetically sealed peripheries of said first and second sheet means.

2. A pneumatic shell structure as set forth in claim 1, further comprising means for hermetically sealing said connection between said support means and said peripheries of said first and second sheet means.

3. A pneumatic shell structure as set forth in claim 1, in which said first strips of synthetic film are made of polyethylene terephthalate resin.

4. A pneumatic shell structure as set forth in claim 1, in which said outer layer of each said sheet means comprises a plurality of second strips of synthetic resin film having longitudinal and transverse extents defining major surfaces thereof,

said second strips being arranged in a configuration which is the same as said configuration of said first strips.

5. A pneumatic shell structure as set forth in claim 4, in which said second strips of synthetic film are made of polyethylene terephthalate resin.

6. A pneumatic shell structure as set forth in claim 5, in which said overlapping marginal surface portions of said second strips are hermetically sealed together.

7. A pneumatic shell structure as set forth in claim 1, in which said inner layer of each said sheet means comprises a plurality of third strips of synthetic resin film having longitudinal and transverse extents defining major surfaces thereof, said third strips being arranged in a configuration which is the same as said configuration of said first strips, and in which said overlapping marginal surface portions of said third strips are hermetically sealed together.

8. A pneumatic shell structure as set forth in claim 7, in which said third strips of synthetic film are made of polyethylene terephthalate resin.

9. A pneumatic shell as set forth in claim 1, further comprising reinforcing means including a synthetic resin film received within said airtight chamber and connected to said first sheet means, said film extending toward said second sheet means in a substantially perpendicular relationship with said first and second sheet means.

10. A pneumatic shell structure as set forth in claim 1, in which said support means is coated with a paint membrane having a pencil hardness of at least F degree and a Sward Riickers hardness value of at least 25, and further comprising means for hermetically sealing said connection between said support means and said peripheries of said first and second sheet means.

11. A pneumatic shell structure as set forth in claim 1, in which said shell structure has a corner portion and further comprising a comer sealing member hemetically sealed to said corner portion.

12. A pneumatic shell structure as set forth in claim 1, in which said first sheet means includes at least one film layer containing an ultraviolet ray absorbing agent means.

13. A pneumatic shell structure as set forth in claim 12, in which said film layer is a synthetic resin film of polyethylene terephthalate, and in which said absorbing agent means is for absorption of ultraviolet rays having wave lengths of at most 350 m 14. A pneumatic shell structure as set forth in claim 1, further comprising a sputtered metal coating on said outer layer.

15. A pneumatic shell structure as set forth in claim 14, further comprising an ultraviolet absorption coating on said sputtered metal coating.

16. A pneumatic shell structure as set forth in claim 14, in which said outer layer is a polyethylene terephthalate film.

17. A pneumatic shell structure as set forth in claim 1, further comprising ventilating means disposed within at least one of said first and second sheet means for venting air contained within said one sheet means to the atmosphere.

18. A pneumatic shell structure as set forth in claim 17, in which said outer layer of each said sheet means comprises a plurality of second strips of synthetic resin film having longitudinal and transverse extents defining major surfaces thereof, said second strips being arranged in a configuration which is the same as said configuration of said first strips, and in which said ventilating means comprises a pipe inserted between said overlapping marginal surface portions of two of said second strips.

19. A pneumatic shell structure as set forth in claim 17, in which said ventilating means comprises a pipe inserted between said outer and intermediate layers at said periphery of said one sheet means.

Claims (18)

1. 2. A pneumatic shell structure as set forth in claim 1, further comprising means for hermetically sealing said connection between said support means and said peripheries of said first and second sheet means.
2. 3. A pneumatic shell structure as set forth in claim 1, in which said first strips of synthetic film are made of polyethylene terephthalate resin.
3. 4. A pneumatic shell structure as set forth in claim 1, in which said outer layer of each said sheet means comprises a plurality of second strips of synthetic resin film having longitudinal and transverse extents defining major surfaces thereof, said second strips being arranged in a configuration which is the same as said configuration of said first strips.
4. 5. A pneumatic shell structure as set forth in claim 4, in which said second strips of synthetic film are made of polyethylene terephthalate resin.
5. 6. A pneumatic shell structure as set forth in claim 5, in which said overlapping marginal surface portions of said second strips are hermetically sealed together.
6. 7. A pneumatic shell structure as set forth in claim 1, in which said inner layer of each said sheet means comprises a plurality of third strips of synthetic resin film having longitudinal and transverse extents defining major surfaces thereof, said third strips being arranged in a configuration which is the same as said configuration of said first strips, and in which said overlapping marginal surface portions of said third strips are hermetically sealed together.
7. 8. A pneumatic shell structure as set forth in claim 7, in which said third strips of synthetic film are made of polyethylene terephthalate resin.
8. 9. A pneumatic shell as set forth in claim 1, further comprising reinforcing means including a synthetic resin film received within said airtight chamber and connected to said first sheet means, said film extending toward said second sheet means in a substantially perpendicular relationship with said first and second sheet means.
9. 10. A pneumatic shell structure as set forth in claim 1, in which said support means is coated with a paint membrane having a pencil hardness of at least F degree and a Sward Rucker''s hardness value of at least 25, and further comprising means for hermetically sealing said connection between said support means and said peripheries of said first and second sheet means.
10. 11. A pneumatic shell structure as set forth in claim 1, in which said shell structure has a corner portion and further comprising a corner sealing member hemetically sealed to said corner portion.
11. 12. A pneumatic shell structure as set forth in claim 1, in which said first sheet means includes at least one film layer containing an ultraviolet ray absorbing agent means.
12. 13. A pneumatic shell structure as set forth in claim 12, in which said film layer is a synthetic resin film of polyethylene terephthalate, and in which said absorbing agent means is for absorption of ultraviolet rays having wave lengths of at most 350 m Mu .
13. 14. A pneumatic shell structure as set forth in claim 1, further comprising a sputtered metal coating on said outer layer.
14. 15. A pneumatic shell structure as set forth in claim 14, further comprising an ultraviolet absorption coating on said sputtered metal coating.
15. 16. A pneumatic shell structure as set forth in claim 14, in which said outer layer is a polyethylene terephthalate film.
16. 17. A pneumatic shell structure as set forth in claim 1, further comprising ventilating means disposed within at least one of said first and second sheet means for venting air contained within said one sheet means to the atmosphere.
17. 18. A pneumatic shell structure as set forth in claim 17, in which said outer layer of each said sheet means comprises a plurality of second strips of synthetic resin film having longitudinal and transverse extents defining major surfaces thereof, said second strips being arranged in a configuration which is the same as said configuration of said first strips, and in which said ventilating means comprises a pipe inserted between said overlapping marginal surface portions of two of said second strips.
18. 19. A pneumatic shell structure as set forth in claim 17, in which said ventilating means comprises a pipe inserted between said outer and intermediate layers at said periphery of said one sheet means.

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