Abstract:
A gutter and sheeting material holding device comprises an elongated body having a bottom wall, and side walls extending from opposed sides of the bottom wall. The bottom and side walls define a gutter for channelling a liquid. Sheet holding channels are provided at a distal end of the side walls. Wedges are inserted into the sheet holding channels for anchoring sheets or membranes to the side walls of the gutter.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to a system and a method for periodically insulating and/or shading a body, such as a building structure, and more particularly to foam distribution parts having integrated membrane fastening structures.  
       DESCRIPTION OF THE PRIOR ART  
       [0002]     Building structures having cavities formed between double light transmitting or other opaque or plastic roof or wall membranes for receiving degradable or replaceable foam insulation arc known. The roof and wall cavities can be periodically filled with degradable foam to provide shading or thermal insulation. However, when it is desired to let the light pass through the building envelope in order to take advantage of the solar energy, the foam can be readily dissolved and removed from the cavities. Examples of such buildings can be found in U.S. Pat. Nos. 3,672,184 and 4,562,674.  
         [0003]     The inner and outer membranes are typically united to each other along their bottom ends so as to define a bottom slope for the purpose of channelling the liquid resulting from the foam degradation to a main liquid tank. The use of the bottom portion of the membranes as a gutter poses several problems, such as 1) the efficient drainage along very long structures having a small slope; 2) the quick removal of the excess liquid draining from the foam or the spray nozzles used for both light shading or washing of the membrane; 3) without a proper gutter, any interference along the drain path can cause an excess accumulation of liquid causing potential stress, bellowing or deforming of the membrane; 4) in winter&#39;s cold temperatures, residue of liquid can freeze rupturing the membranes and cause leaks; and 5) the accumulation of dust, bugs and other matter in corners, unequal tighten membranes. The suction effect at the outlet also tends to close the membranes one against the other, thereby inhibiting: the flow of liquid.  
         [0004]     Accordingly, there is a need for a new double-walled cavity gutter arrangement.  
         [0005]     Furthermore, the fixing of the membranes to the greenhouse skeleton framework has heretofore required the use of several external fastening pieces which contributes to increase the installation time and costs. There is a thus need for an integrated foam distribution and sheet anchoring system.  
       SUMMARY OF THE INVENTION  
       [0006]     Therefore, in accordance with an aspect of the present invention, there is provided a periodically shieldable solar structure comprising an inner membrane and an outer membrane defining therebetween an internal cavity, a foam generating system for selectively filling said internal cavity with degradable foam, said inner and outer membranes being united along a lower end thereof by a gutter interposed between the inner and outer membranes and defining a top open-ended channel for receiving and channelling the liquid resulting from foam degradation and/or from a liquid spraying system, the gutter having a mounting flange for allowing the gutter to be mounted to a framework of the shieldable solar structure, the gutter further having first and second side walls provided with respective sheet holding means for respectively fixedly anchoring said inner and outer membranes to said first and second side walls of said gutter.  
         [0007]     In accordance with an another aspect of the present invention, there is provided a building structure comprising a double-walled insulation space having a bottom formed by a channel-shaped extrusion interposed between an inner membrane and an outer membrane, the channel-shaped extrusion having a bottom surface and first and second longitudinal side walls extending from said bottom surface, said inner and outer membranes being respectively fixed to said first and second longitudinal side walls.  
         [0008]     In accordance with a further aspect of the present invention, there is provided a fastening device for fixing first and second membranes to a framework, comprising a main member adapted to be mounted to the framework, said main member having first and second arms interconnected by a bottom web, said bottom web and said first and second arms forming a gutter, said first and second arms being respectively provided with first and second sheet keeper receiving channels at respective distal end portions thereof relative to said bottom web, said first and second sheet keeper receiving channels being adapted to respectively receive first and second sheet keepers in locking engagement therewithin in order to respectively fixedly hold one end of the first and second membranes in said first and second sheet keeper receiving channels such that the gutter extends between the membranes.  
         [0009]     In accordance with a still further general aspect of the present invention, there is provided a gutter and sheeting material holding device combination comprising an elongated body having a bottom wall, and first and second side walls extending from opposed sides of said bottom wall and defining therewith a channel for channelling a liquid, first and second sheet holding channels respectively provided at a distal end of said first and second side walls, and first and second mating wedges respectively insertable into said first and second sheet holding channels for anchoring first and second sheets to said first and second side walls.  
         [0010]     In accordance with a still further general aspect of the present invention, there is provided a pipe extrusion comprising an elongated wall structure having a closed cross-section defining a longitudinal passage for channelling a fluid, and first and second longitudinal channels provided on an outer side of said wall structure for respectively receiving membrane wedging inserts in locking engagement therewithin. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof, and in which:  
         [0012]      FIG. 1  is a front cross-sectional view of a greenhouse having a foam distribution system for periodically insulating and/or shielding the shell of the greenhouse;  
         [0013]      FIG. 2  is a cross-sectional view of one of the distribution lines of the foam distribution system, the distribution line including a 3-pipe assembly and a plurality of foam generators mounted to an extruded air pipe provided with integral membrane fastening members and pipe attachment in accordance with an embodiment of the present invention;  
         [0014]      FIG. 3  is a cross-sectional view of a gutter assembly with double membrane fastening devices in accordance with an embodiment of the present invention; and  
         [0015]      FIG. 4  is a cross-sectional view of a gutter assembly with double membrane fastening devices suited for openable roof sections in accordance with a further embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     Now referring to  FIG. 1 , there is shown a greenhouse  10 , as an example of a typical structure, having a conventional skeleton framework including among others a number of vertical supporting columns  12  and transversal trusses  14 . The greenhouse  10  has a double-walled roof structure  16  comprising inner and outer membranes  16   a  and  16   b  stretched over the skeleton framework of the greenhouse  10 . Longitudinal gutters  15  are provided at the lower end of each sloping roof sections to channel and carry off rainwater flowing over the outer membranes  16   b.    
         [0017]     The inner and outer membranes  16   a  and  16   b  are typically made of polyethylene sheet or other flexible sheeting materials such as polycarbonate, glass or other forms of plastic to form the skin of the structure. Each set of inner and outer membranes  16   a  and  16   b  defines therebetween a roof cavity  17 . A foam distribution system  18  is provided for periodically filling the roof cavities  17  with degradable foam F. The foam distribution system  18  can be similar to the one described in Applicant&#39;s PCT application PCT/CA2004/001083 or PCT/CA2005/000360. The content of these applications is herein incorporated by reference. However, it is understood that the foam distribution system  18  is not material to the present invention. The foam distribution system  18  generally comprises two independent, automatically controlled, air and foaming solution supply systems  19  and  21  feeding longitudinal foam distribution lines  22  mounted directly in the roof cavities  17  at the crest thereof. The foaming solution is composed essentially of surfactant and water. For instance, a concentrated solution derived from a hydrolyzed protein concentrate base, such as used in the fire fighting foam art could be used. Although the preferred liquid is water, it is understood that other liquids compatible with the surfactant could be used as well.  
         [0018]     As shown in  FIG. 2 , each foam distribution line  22  is mounted on a tubular member  24  forming part of the framework of the greenhouse  10  and extending on top of the trusses  14  from a front end to a rear end of the greenhouse  10 . Each foam distribution line  22  can, for instance comprises a 3-pipe assembly including an air pipe  26 , a liquid soap or surfactant pipe  28  and a water pipe  30 . Two sets of longitudinally spaced-apart foam generators  32  are mounted on opposed sides of the air pipe  26 . Each foam generator  32  is connected in fluid flow communication with the air pipe  26  via a central air passage thereof. The foaming solution is fed from the surfactant pipe  28  into each foam generator  32  via appropriate tubing  34  and nozzles  36 . The nozzle(s)  36  of each foam generator is/are angularly disposed to spray the surfactant solution onto the entire surface of a screen  38  mounted at the distal end of the foam generator  32 . As the air fed into the generator  32  flows through the wet screen  38 , foam is generated. In this way, the roof cavities  17  can be selectively and independently filled with foam F. Over times, the foam F will collapse, thereby leaving the roof cavities empty. If desired, a vacuum system could also be used to remove the foam F from the roof cavities  17 .  
         [0019]     After several foam generation and degradation cycles, it might be necessary to wash the inner face of the membranes  16   a  and  16   b  in order to wash out any soap or surfactant residues that could otherwise impede the sun rays to pass through the roof of the greenhouse  10 . Accordingly, the water pipe  30  is connected in fluid flow communication with a source of water (not shown) and sprinklers  40  are distributed along the length of the water pipe  30  to spray clean water onto the inner face of the inner and outer membranes  16   a  and  16   b.    
         [0020]     As can be appreciated from  FIG. 2 , the air pipe  26  can be provided in the form of an extrusion having an integral double sheet fastening structure  42  and an integral pipe mounting structure  44 . More particularly, the air pipe  26  has a cylindrical wall  46  defining a longitudinal passage for feeding the air to the foam generators  32  distributed along the roof cavities. The integral sheet fastening structure  42  comprises a pair of channels  48  extending longitudinally on an outer surface of the cylindrical wall  46 . The channels  48  are symmetrically disposed relative to a central axis of the cylindrical wall  46 , the open side of the channels  48  facing away from that axis of symmetry. Each channel  48  is configured to receive a keeper, a mating wedge or sheet retaining insert  50  in locking engagement therein in order to fixedly hold an end portion of one of the inner membranes  16   a.  According to another non-illustrated embodiment, the double sheet fastening structure  42  and the integral pipe mounting structure  44  are extruded together as a single part separate from the air pipe  26 . The sheet fastening structure  42  and the pipe mounting structure  44  and are then bolted to the air pipe to form an air pipe/sheet fastening assembly adapted to be mounted as a unitary part to tubular member  24 . Accordingly, the air pipe  26  can be used to secure two adjacent inner membranes  16   a  to the framework of the greenhouse  10 , as depicted in  FIG. 2 . The air pipe  26  has thus a dual function. It acts as an air duct and as a sheet fastening structure. The inner membranes  16   a  are anchored to the air pipe  26  by positioning respective end portions thereof in the channels  48  and by then inserting the sheet retaining inserts  50  in the channels  48  in locking engagement therein so as to securely wedge the end portions of the inner membranes  16   a  between the inner surface of the channels  48  and the inserts  50 . It is understood that the channels  48  and mating wedge or sheet retaining inserts  50  could have various configurations. For instance, U.S. Pat. No. 5,009,540 discloses one possible configuration. The configuration of other commercially available film locking devices could also be embodied in the air pipe extrusion.  
         [0021]     The integral pipe mounting structure  44  includes a saddle  52  extending between the channels  48 . The saddle  44  is seated on top of the greenhouse framework tubular member  24  and is configured to generally follow the curvature thereof. The mounting structure  44  further includes a pair of mounting legs or flanges  54  depending from the underside of the channels  48 . Longitudinally spaced-apart holes are defined along the length of the mounting flanges  54  for allowing the air pipe extrusion to be bolted to brackets  56  which are in turn adapted to be secured to the framework of the greenhouse using self-tapping screws (not shown) or the like.  
         [0022]     As best seen in  FIG. 3 , the lower end portions of the inner and outer membranes  16   a  and  16   b  are attached to the greenhouse framework via a longitudinally extending gutter  58  interposed between each pair of inner and outer membranes  16   a  and  16   b  for collecting and channelling the liquid resulting from the foam degradation as well as the water sprayed on the inner face of the membranes by nozzles  40 . Therefore, the bottom ends the roof cavities  17  are formed by distinct gutter pieces. Each gutter  58  is preferably extruded in the form of an elongated channel  60  having an arcuate bottom  62  and a pair of side walls  64   a,    64   b.  A sheet locking channel  66  is formed at the distal end of each side wall  64   a,    64   b  for receiving a sheet retaining insert  50  in order to fixedly hold the lower ends of the membranes  16   a,    16   b,  as described hereinbefore with respect to the air pipe  26 . The inner membrane  16   a  is retained captive in channel  66  of wall  64   a  and the outer membrane  16   b  is retained captive in channel  66  of wall  64   b.  The locking channels  66  generally have the same configuration as the channels  48 . A recess  49  can be provided in the channels  66  to receive the heads of fasteners, such as bolts or screws, for mounting the roof cavity gutter  58  to an adjacent framework structure. However, in the illustrated examples, the roof cavity gutters  58  are bolted to the greenhouse gutters  15  via a mounting leg  70   a  extending from an underside of the bottom  62  of the gutters  58 . A second leg  70   b  extends from the underside of the gutter bottom  62  as an extension of the gutter side wall  64  facing the first leg  70   a.  In some alternative mounting arrangements for greenhouses having openable roof sections, the second leg  70   b  is adapted to rest on an underlying greenhouse framework member to prevent water infiltration when the roof section is pivoted to a closed position thereof.  
         [0023]      FIG. 4  illustrates another embodiment of a roof cavity gutter  58 ′ specifically designed for openable roof sections. According to this variant, the gutter  58 ′ is not mounted to a greenhouse gutter  15 , but rather to the framework structure  75  of a roof section adapted to be pivoted between an open position in which the skeleton structure  75  is held at a distance away from gutter  15  and a closed position in which the skeleton structure  75  rests on the gutter  15 . The gutter  58 ′ shown in  FIG. 4  differs from the gutter  58  shown in  FIG. 3  in that the mounting structure thereof includes a back channel  76  configured to receive the lower end of the arms of the roof skeleton structure  75 . The back channel  76  has a square cross-section defined by a straight bottom wall  72 , a short leg  70   c  and an opposed long log formed by wall  64 ′ of channel  60 ′ and mounting leg  70   a′.  A reinforcing web  74  extends between the lower ends of legs  70   a′  and  70   b′.  A number of longitudinally spaced-apart bolts  78  extend through legs  70   a,    70   b,    70   c  and the arm of the framework structure  75  for securing the gutter  58 ′ to the openable roof section. Screws  80  are also use to fix the gutter  58 ′ to the framework of the openable roof section. The end of the screws  80  are received in the recess  49 ′ portion defined in the sheet receiving channel  66 ′ of the back wall  64  of channel  60 ′.  
         [0024]     Referring back to  FIG. 1 , we will now describe the installation procedure of the inner and outer membranes  16   a  and  6   b  for one greenhouse section. A first inner membrane  16   a  is anchored at a first lower end thereof to a first roof cavity gutter  58   a  and at a second upper end thereof to the air pipe  26  of foam distribution line  22 . A second membrane  16   a′  is then anchored at a first upper end thereof to the air pipe  26  and at a second lower end thereof to a second roof cavity gutter  58   b.  Thereafter, the outer membrane  16   b  is anchored at a first lower end thereof to the first roof cavity gutter  58   a  and at a second lower end thereof to the second roof cavity gutter  58   b.  The outer membrane  22  is supported at midway between the opposed ends thereof by the central foam distribution line  22 . By so using foam distribution parts (i.e. the air pipe  26  and the gutters  58 ) to fix the membranes  16   a,    16   b  and  16   c  to the greenhouse framework, the number of pieces required to complete the installation can be minimized.  
         [0025]     The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without department from the scope of the invention disclosed. Any modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.