JPS6127011B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a translucent double clad assembly.

It is known to insert insulating and translucent double-sided panels between adjacent spaces with different temperatures to reduce the transfer of thermal energy. The agricultural greenhouse disclosed in French Patent No. 2,315,844 is a translucent double-walled assembly consisting of a hollow body made of expanded plastic film. Although such an assembly has sufficient insulation properties for horticultural or agricultural purposes, it has been found that since the thin film is double-layered, each of the four surfaces scatters incident light and prevents sunlight from passing through. did. In this way, there is little light transmission, so
Delays photosynthesis in plant growth. Retardation of plant growth due to low sunlight intensity and irradiation period partially or completely eliminates economic benefits for farmers, even though double-walled greenhouses conserve energy.

The translucent double-walled assembly according to the invention can be used in horticultural and agricultural greenhouses, which can be suitably insulated during the night and suitably transparent during the day. Although the invention is described herein with respect to horticultural and agricultural greenhouses, it will of course be appreciated that the double clad assembly may be used in other structures.

The translucent double-walled assembly of the present invention consists of two flexible thermoplastic thin film sheets that transmit light and a frame that supports them, and these two sheets are held together by the frame. a translucent double-walled assembly separated from each other, the sheet and frame forming a substantially gas-impermeable closed space, the closed space being connected to a means for evacuating the closed space; .

When this confined space is evacuated, the opposing inner surfaces of the two membrane sheets come together in intimate surface-to-surface contact, forming a single membrane twice the thickness of the sheets over the entire contact area. It is a translucent double clad assembly provided to exhibit the effect.
As a result, the surfaces of the thin films are brought into optical contact with each other, and light scattering at the interface can be partially or completely eliminated. As a result, during the day,
This translucent double-walled assembly can be evacuated since maximum sunlight penetration is important to promote plant growth in the greenhouse, and conservation of thermal energy is less important. .

Preferably, the means for evacuating the enclosed space is a vacuum pump which partially or completely evacuates the fluid in the enclosed space, usually air, from the enclosed space.

Evacuating the enclosed space of this translucent double clad assembly places internal tension on the sheet, thereby increasing the structural stiffness of the panel. Therefore, the frame used for this panel can be a simple lightweight material. For example, thermoplastic materials such as vinyl chloride polymers or copolymers or olefin polymers or copolymers, or extruded profiles of metals such as aluminum can be used. Comparing the entire panel to the same area, it is generally lighter than a typical glass window, so the structural support for the greenhouse can be lighter.
Economically advantageous. Additionally, a larger area of translucent double-paned assemblies can be used than the typical glass windows normally used in greenhouses. Therefore, the number of structural supports and frame bars is reduced, so that the amount of light absorbed by the structural supports can be reduced.

When the assembly is not evacuated, the membrane sheets remain separated by the frame. The enclosed space surrounded by this sheet acts as a heat insulator and conserves the thermal energy required depending on the geographical conditions. However, by expanding this closed space and widening the spacing between the thin film sheets, the heat insulation effect can be further improved. Expanding this enclosed space can also create internal tension in the sheet, increasing the structural stiffness of the panel.

The invention therefore also connects the enclosed space of the panel to means for inflating this enclosed space.

When the panel is inflated, the flexible thin film sheet curves outward. The amount of expansion in the center of the closed space between the two thin film sheets is greater for large panels than for small panels. Means may be provided to limit deformation of the membrane sheet during expansion by riveting or gluing the two sheets at selected points throughout the panel area to control the amount of expansion.

Expanding this closed space between the sheets is
This can be done using a pressurized gas source. Air is preferable because it is convenient. Pressurized air can then be pumped into this closed space by means of a pump. The pressurized gas can also be supplied from a pressurized source such as a pressurized gas pump. Gases suitable for such supply are nitrogen or carbon dioxide.
In general, it is necessary to optimally conserve thermal energy in the greenhouse during the night. At night, the scattering of incident light on the panel is not a substantial problem. Accordingly, as noted above, the translucent double-walled assemblies of the present invention are generally expanded during the night to conserve thermal energy and vented during the day to optimize translucency. In addition,
Even during the day, double-paned panels should be inflated when the temperature drops significantly and is significantly colder than the normal growing temperature maintained in the greenhouse by the normal intensity of sunlight. This is economically advantageous because it conserves energy.

If the double-paneled assembly has exhaust means as well as air blowing means, the connection of these means is preferably done through the frame of the panel.

A greenhouse can be constructed using a number of light-transmitting double-paned assemblies of the above structure according to the present invention. A frame grid consisting of extruded profiles of metal, such as aluminum, or bars of thermoplastic profiles can be used to support this double-sided assembly.
The structure consisting of double-paneled panels and frame bars can then be further supported by load supports interconnected with steel profiles, for example.

Preferably, some or all of the frame bars of this structure have conduits. By means of this conduit, the double-lined assembly can be connected, preferably through the frame of the assembly, to exhaust means and also to ventilation means, if any. This can be done, for example, by using hollow extrusions, such as aluminum profiles, as a frame bar, which is provided with suitable communication means for interconnecting the double-paneled panels, the exhaust means and optionally the ventilation means. It is also self-evident that if each of the double-clad panels is connected to exhaust means and optionally to blowing means, it is not necessary for every frame bar to have such a conduit; Some of them may be simply solid sections.

Accordingly, in an embodiment of the invention, the double clad assembly comprises at least one panel as described above;
This is integrated with a frame bar having a conduit that connects the closed space of the panel to the exhaust means, more preferably also to the blowing means.

Preferably it is separated into several transparent compartments with a plurality of double clad panels. The panels in each compartment can be connected to independent exhaust means and any ventilation means, so that even if the exhaust means fails in one compartment, the rigidity of the other compartments will not be affected and the overall structure of the greenhouse will not be damaged. .

In another embodiment of the present invention, pumps are used to evacuate or inflate the enclosed space of the double-sided panel, and the pumps are suitably kept in continuous operation as the enclosed space is evacuated or inflated. You can also do that.

Materials for flexible, translucent thermoplastic thin films used in panels include styrene polymers and copolymers, polyamides, vinyl chloride polymers and copolymers, polyvinyl fluoride, and polyvinylidene fluoride. , polycarbonates and polymers and copolymers of olefins such as polyethylene, polypropylene, polysulfones and
There are linear polyesters, such as terephthalic acid, isophthalic acid, phthalic acid, 2,5-, 2,6- and 2,7-naphthalene dicarboxylic acids, succinic acid, sebacic acid, adipic acid, azelaic acid. acid, one or more dicarboxylic acids or lower alkyl diesters thereof, such as diphenyldicarboxylic acid, and hexahydrophthalic acid, or bis-p-carboxylphenoxylethane, optionally with a monocarboxylic acid such as pivalic acid, for example ethylene glycol,
It is a polyester obtained by condensation with one or more glycols such as 1,3-propanediol, 1,4-butanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol.

Preferably, the film is transparent, but a slightly opalescent film can also be used to diffuse light through the panel. For example, a transparent thin film can be used as the outer layer, and a slightly opalescent thin film can be used as the inner layer.

Linear polyester films, particularly biaxially oriented and heat-set polyethylene terephthalate films, are particularly suitable for forming double-sided panels;
The thickness can be at least 12 μm. The greater the thickness, the greater the durability and resistance to accidental punctures. The thickness of the thin film sheet may vary to obtain satisfactory properties. A polyethylene terephthalate film approximately 125 μm thick can be used as the outer and/or inner layer. If membranes of different thicknesses are used, the outer layer can be about 125 μm and the inner layer about 12 μm.

To improve the optical properties of the inner contact surface of the thin film sheet, the surface of the thin film can be treated or coated, if desired, to reduce reflection or scattering of light at the surface. For example, in the case of the preferred polyester membranes, the inner surface can be coated with glycerin or silicone oil to insert liquid between the contact surfaces. A water layer is also effective. Usually present within the panel, but may also be intentionally introduced into the panel, since when a panel made of polyester thin film is expanded, water permeates the film from the humid air of the greenhouse and condenses on this surface. . Alternatively, the surface of the thin film can be roughened, embossed, or coated with a resinous material such as gelatin, which has high light transmission and low scattering or reflection of light. The refractive index of the thin film surface treatment or coating agent that reduces light scattering or reflection is preferably in the range of the refractive index of air and that of the polyester thin film, and should be between these refractive indexes. However, it is also preferable.

The thin film sheet and optionally the inner surface of the frame can be sterilized to prevent mold growth. This includes:
For example, treatment with ethylene oxide.

Many thermoplastics tend to deteriorate and become brittle when exposed to ultraviolet light over long periods of time. Therefore, when assembling the panels into a greenhouse, at least the outer sheet should be stabilized against such deterioration. It is also preferable to process the sheets of both layers. This can be done, for example, by subjecting the thin film to a suitable stabilizing treatment or by incorporating a suitable ultraviolet light-absorbing compound into the thermoplastic material.

If, due to the geographical conditions in which the greenhouse is located, the solar radiation is long and intense and introduces excessive thermal energy, the intensity of the solar radiation transmitted into the greenhouse may be A device can be provided to control the Therefore, each thin film sheet can be provided with a shattered pattern. This shatter pattern is a solar radiation-absorbing material, for example a set of parallel lines or bands, which can be applied to the surface of a thin film so that when the enclosed space of the panel is not inflated or evacuated, the shatter pattern Let them be in a state of misalignment. When partially or completely inflating or evacuating the enclosed space of the panel,
As the thin film sheets move relative to each other, the shutter pattern also moves accordingly. The degree of expansion or evacuation is varied to control the degree of shading of the shutter and hence the absorption of incident radiation.

Another means of controlling the transmitted intensity of solar radiation is to run a light-absorbing fluid through some or all of the panels that make up the greenhouse. Since photosynthesis is carried out by visible light having wavelengths less than about 700 nm, it is preferred to use a fluid that absorbs this light, such as an aqueous solution of copper chloride.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.

The translucent double-sided panel 1 shown in FIGS. 1 to 4 consists of two sheets 2 and 3, which are biaxially oriented and heat-set transparent polyethylene terephthalate thin films. Thickness: 125
This membrane of .mu.m is glued to a rectangular lightweight frame 4. The frame is formed from polyvinyl chloride extrusions and is glued together at the corners. The sheets 2, 3 are separated from each other by about 1 cm by a frame 4 with a thickness of about 1 cm. The sheets 2, 3 are kept taut, as shown in FIG. 2, when not inflated or evacuated.

The panel 1 is constructed by adhering the frame members 4 to each other and between the sheets 2 and 3 and the frame 4 to form an air-impermeable closed space 5. As shown, closed space 5
communicates with the vacuum pump 8 from the exhaust pipe 6 through the frame 4. This vacuum suction brings the panel 1 into the state shown in FIG.

The air pipe 7 also communicates with the closed space 5 through the frame 4,
The structure of the blower pipe 7 is similar to the exhaust pipe 6 shown in FIGS. 2, 3 and 4, and communicates with the blower pump 9 as shown in FIG. This air pressurization causes the panel 1 to be expanded as shown in FIG.

Although the vacuum and air pumps 8 and 9 are not shown in detail, they may have a conventional configuration.

Agricultural greenhouses can be constructed using multiple translucent double-paned assemblies such as those shown in FIGS. 1-4. At night, the panels are inflated to the state shown in Figure 3 to conserve energy, and during the day they are vented to the state shown in Figure 4 to optimally transmit sunlight to the greenhouse.

Bars 11, partially shown in Figures 5 and 6, support each edge of the two double-sided panels. The two sheets 14 and 15 constituting the double-paned panel 12 are biaxially oriented and heat-set transparent polyethylene terephthalate thin films with a thickness of 125 μm, which are attached to the web 16 of the aluminum extrusion frame 18. , 17, the dimensions of which are the sheets 14, 1
5, so that they are supported about 2 cm apart. sheet 1
4 and 15 are glued to frame 18 so that they remain taut when not assembled, evacuated or inflated. The inner surfaces of sheets 14, 15 are coated with a thin layer of silicone oil. Panel 13 also has a similar structure to panel 12.

The bar 11 has a main hollow part 20 with a rectangular cross-section, from which arms project. The slit 21 formed by the webs 22, 23 receives the head of one or more threaded bolts. This bolt, not shown in Figures 5 and 6, secures the bar 11, panels 12, 13 to the greenhouse load support.

Flanges 24 and 25 are aluminum form frame 18
The connecting balls 26 and 27 are formed so as to accommodate and engage with each other, so that when assembling the panel, the panel 1 is attached to the bar 11 as shown in FIG.
2 and 13 can be installed.

The bar 11 has two fixing flanges 29, 30 that engage with a closing member 31, which is made of polyvinyl chloride whose shape is difficult to deform and is cross-linked, as shown in FIG. Since the portion 32 is flexible, it can be deformed to form the fixed flange 2.
It can be fitted across 9 and 30. This closure member 31 is made easy to deform, and the fixed flange 2
In order to make it easier to straddle the slits 34 and 30, use a suitable tool not shown in FIGS.
35 and can be deformed. 6th
As shown in the figure, the fixing surface 3 of the closure member 31
6, 37, 38, 39 engage the flanges 29, 30 with the connecting balls 26, 27 of the aluminum form frame 18 to fix the panel to the bar 11.

The locking band member 40 is an extruded polyvinyl chloride profile that is positioned within the groove 41 of the closure member 31 so that the small ridge portion 42 of the locking band member 40 is connected to a corresponding small groove provided in the wall of the groove 41. and secure it. As shown in FIG. 6, a lock band member 40 for assembling the component parts
The closing member 31 is the fixing flange 2 of the bar 11.
9 and 30 so that the panel 1 and the bar 11 are not separated.

The main hollow part 20 of the bar 11 is the panel 12,
13 and the pump 45 are connected. This pump has a normal structure and will not be described in detail, but the panel 12,
It has an adjustable valve to vent or inflate 13. As shown in FIG. 6, panels 12 and 13 are interconnected by apertures 46 in the wall of bar 11 and corresponding apertures 47 in panel frame 18. Note that these openings are not shown in FIG. The space between the panel 12 and the bar 11 is hermetically sealed by a rubber stopper 48 having a central hole 49 located between the panel 12 and the bar 11 when the components are assembled.

Next, the improvement in light transmittance obtained when the double-walled assembly of the present invention is evacuated was evaluated using ASTM test D-1003.
-61 by the following total transmittance.

Constituent conditions Total light transmittance (%) Single layer of transparent polyethylene terephthalate thin film with a thickness of 125 μm used for sheets 2 and 3 of the drawing 87 Panel 1 shown in Figure 2 75 Evacuated panel 1 shown in Figure 4 86

[Brief explanation of the drawing]

FIG. 1 is a plan view of the translucent double-walled assembly of the present invention, FIG. 2 is a sectional view taken along the line -- in FIG. 1, and FIG. Figure 4 is a cross-sectional view of the body, and Figure 4 shows the second section with the panel evacuated.
FIG. 5 is a cross-sectional view of the components of another embodiment of the present invention, and FIG. 6 is a cross-sectional view of a portion of the assembly assembled with the components of FIG. It is a diagram. 1, 12, 13...double panel, 2, 3, 1
4, 15... Sheet, 4, 18... Frame, 5... Closed space, 6... Exhaust pipe, 7... Air pipe, 8... Vacuum pump,
9... Air pump, 11... Bar, 16, 17, 2
2, 23...web, 20...hollow part of bar, 2
1, 34, 35...slit, 24, 25, 29,
30...Flange, 26,27...Run ball, 31,43
...Closing member, 32...Bridging portion, 36, 37, 3
8, 39... Fixed surface, 40... Lock tourniquet material, 41...
Groove, 42...Small ridge part, 45...Pump, 46, 47
...opening hole, 48...rubber stopper material, 49...center hole.

Claims (1)

[Claims] 1. Consisting of two flexible thermoplastic thin film sheets that allow light to pass through uniformly and a frame that supports them, these two sheets are separated by the frame, and this a translucent double-walled assembly, wherein the sheet and the frame form a single closed space that is substantially impermeable to gas, said closed space being connected to means for evacuating said closed space; As the evacuation means evacuates the closed space, the opposing inner surfaces of the two thin film sheets come into close surface-to-surface contact, thereby causing the contact area to be evacuated. A translucent double-sided assembly arranged to exhibit the effect of a single thin film having the combined thickness of two sheets across. 2. The translucent double-walled assembly according to claim 1, wherein the thermoplastic thin film is a linear polyester thin film. 3. A translucent double clad assembly according to claim 1, wherein said closed space communicates with said exhaust means through said frame. 4. A translucent double-walled assembly according to claim 1, comprising a bar containing a conduit communicating said enclosed space with said evacuation means. 5. A translucent double clad assembly according to claim 4, wherein said bar has a hollow shape. 6 Consisting of two flexible thermoplastic thin film sheets that transmit light and a frame that supports them, these two sheets are separated by the frame, and the sheet and frame are substantially A translucent double-paned assembly forming a single gas-impermeable enclosed space, said enclosed space being connected to means for evacuating said enclosed space, and also having means for inflating said enclosed space. As the evacuation means evacuates the closed space, the opposing inner surfaces of the two thin film sheets come into close surface-to-surface contact, thereby causing the evacuation means to evacuate the closed space. A translucent double-sided assembly arranged to exhibit the effect of a single thin film having the combined thickness of two sheets over the contact area. 7. The translucent double-walled assembly of claim 6, wherein the thermoplastic thin film is a linear polyester thin film. 8. A translucent double-walled assembly according to claim 6, wherein the enclosed space communicates with the exhaust means through the frame. 9. A translucent double-walled assembly according to claim 6, comprising a bar containing a conduit communicating said enclosed space with said evacuation means. 10. The translucent double clad assembly of claim 9, wherein said bar has a hollow shape.