HEAT-INSULATING ROLLER-BLIND

Abstract: heat-insulating roller-blind (2) which is intended to be placed in front of a window in order to save energy in buildings. The blind consists of two thin, transparent, hermetic, congruent sheets (10, 12) which at their outer edges are hermetically joined to form a closed space (14). A valve (8) is arranged to enable, in its open position, admission of room air into said space, thus obtaining a non-circulating and thus heat-insulating air layer of substantially atmospheric pressure between the sheets upon closure of the valve. In its open position the valve permits the outflow of air from said space when the blind is rolled up.

Description: The present invention concerns a heat-insulating roller-blind intended to be placed in front of a window In connection with the realization that the energy supplies are limited and that the cost of energy has risen considerably it became important to save on the heating energy. New building standards have b developed for the purpose of increasing the heat-insulating capacity o new houses and measures have been accepted for additional insulation o previously built houses According to the new construction standards t window surface area is limited to a certain percentage of the facade surface. Furthermore, three-glass windows are prescribed in order to increase the heat-insulating capacity of the windows and thus to decre additionally the heat loss through the window- T e purpose of the present invention is to save energy in buildings This purpose is achieved by means of a roller-blind indicated in the introduction, with characteristics described in claim 1. The basic principle of the invention is that two or more thin sheets of a transparent material are joined to form a closed space so that the room-air can enter through a valve into the space enclosed by the sheets and, when the valve is closed, this gas remains inside and forms an immobile air layer of substantial atmospheric pressure with a heat-insulating capacity- The effect of the roller-blind consists in that simultaneously as it lets into the room the major portion of sunlight and thermal radiation, it prevents the heat from going out of the window. Heat-insulating capacity in a structure is the resistance offered by the latter to the heat passage. Heat passage number = k = _ = 1/m = k, heat resistance which entails that the lower the k-value of a structure the better the heat-insulating capacity of the structure. Thus; a single window = a window with one window pane has a k-value - = 7.2; a double window = a window with two panes + the enclosed air laye has a k-value =• 2.9 The k-value for a composite structure of the heat-insulating roller-blind according to the invention may by means of the established calculation methods be theoretically calculated according to the following: Surface resistance πi^ + ^. = 0.20 Resistance of the window pane = 0.01 Resistance of the air space of 2.5 cms = 0-20 Resistance of the window pane = 0.01 Resistance of the air space of 12 cms = 0.21 Resistance of the plastic sheet = 0.10 Resistance of the air space of 6 cms = 0.22 Resistance of the plastic sheet * 0.10 Total heat resistance = m = 1.05 k = 1/m = 1/1.05 - k-value = 0.95 m i and m in the above table indicate the internal and the external surface resistance, respectively. The roller-blind according to the invention, is suspended from a curtain rod of conventional design above a window in a manner permittin it to be rolled up. The roller-blind according to the invention is expected to remain pulled down during the day and for this reason it is transparent The roller-blind is thus suitably manufactured of a glass-clear material of such hardness that the sheets are sufficiently stiff to form flat surfaces in front of the window when the blind is down, so that the vie through the window is not distorted. Suitably the sheets consist of a plastic material with good thermal properties, so that they do not melt or catch fire through an accidental contact, for example with an electr heat radiator. It is usually desirable that as great a portion as possible of th sun's luminous flux should enter through the window A sheet therefore consists of a material which has the greatest possible transmission, 85 to 90%, in other words, a transparent material. In certain cases (for example in sun-warm areas with cold nights) it may be desirable to bar the thermal radiation but to allow the entrance of the luminous radiation. In this case sheets of a plastic material are used which reflect (bar) the infrared light (= the thermal radiation). In such case the blind serves as a heat-insulator during th night. According to the invention the roller-blind should have a surface which is 10 to 20% larger than the surface of the window which it is to cover. "Bϋ_ cAt To obtain special .structural properties of the roller-blind according to the invention a special gas may be introduced between th sheets instead of dry air. For example a) a gas which is lighter than air, to facilitate the erection of the construction with skylights in roof, in which case the blind is supported by the air pressure and consequently only needs to be stabilized in the horizontal plane, b) carbon dioxide, which is capable of extinguishing fire. When the roller-blind according to the invention is to be rolled up on the curtain rod the air valves are opened, so that the air may b squeezed out when the blind is rolled up In order that the blind shou be able to be rolled up swiftly and conveniently the valve must have a very high evaucation capacity. In an advantageous embodiment of the roller-blind according to the invention the valve is designed as a slit-valve which runs along a considerable length of the ' blind's lower edge. As already mentioned the blind according to the invention should be manufactured of a material which is so hard that the sheets have a . certain degree of stiffness. When two such congruent sheets are rolled up for example around a curtain rod, a certain displacement between th sheets occurs in the direction of the rolling-up. Therefore, the sheet cannot be unresiliently connected to each other at the edges, for example by welding. This problem is solved according to the invention that a soft and/or elastic edge-band which may absorb the displacement attached at the edges on all the external sides of the sheets. In order to achieve a further air layer between the window and th blind stretching devices may be installed to squeeze the air-filled and thus elastic blind in such a manner that it connects hermetically to th window embrasure and/or to the linings around the window. When the thickness of an air layer exceeds a certain maximum valu air currents may originate within the layer, resulting in decreased heat-insulating capacity of the layer is decreased to the same extent a the increase of the thickness of the layer and with that the increase o the air currents There are windows in which the distance between the panes is so great that this phenomenon is taking place. By placing a blind according to the invention in such a space between the panes one obtains three heat-insulating layers with a considerable total heat- insulating capacity. An embodiment chosen as an example will be described below in embodiment of the roller-blind, according to the invention pulled down over » a window Fig. 2 shows a lateral view of the roller-blind accordi to F . ig. 1 seen in cross-section and Fig. 3 shows a detailed view of th grasping device (catch) for the separation of the sheets of the roller blind ' for the filling with air. Fig. 4 is a detailed view of the rolle blind' in the air-filled condition in lateral view and in cross-section and Fig. 5 shows a detailed view according to Fig. 4 with the roller- blind in its deflated condition. Fig- 1 shows a roller-blind 2 pulled down in front of a window. roller-blind 2 is attached to a roller-blind rod 4 which may be of a conventional kind and attached over the window in the usual way. At th lower edge of the roller-blind a catch designed as a brace is attached to hold the roller-blind under the window. The brace 5 must be attache at* the two lateral edges of the roller-blind and at the middle of the blind's bottom edge. At the bottom part of the roller-blind a slit val is also arranged for filling the blind with air and for emptying it. T give the valve great evacuation capacity it extends along a considerab part of the bottom edge of the blind 2. As shown in Fig. 2 the roller-blind 2 consists of two thin sheet 10, 12. The sheets 10, 12 consist of a transparent hermetic material which is flexible but still has a certain stiffness in order to form f surfaces in front of the window when the blind is down so that the vie is not distorted. The sheets suitably consist of a plastic material, s as a polyester film (polyethyleneterephtalate)- Suitable thickness of film is 75 microns. The sheets are joined along their outer edges to for an enclose space 14. The lateral and bottom edges of the sheets 10, 12 are joined by a border band 16, see also Fig ' s- 4 and 5- The border bands 16 are s and elastic so that they may absorb the displacement between the sheet 10, 12 when tolled up over the curtain rod 4. Furthermore, the border bands are wide enough to absorb the expansion between the sheets 10, 1 when air flows in between them, as shown in Fig- 4. The air valve 8 is suitably designed as a slit in the border ban 16 at the lower edge of the roller-blind 2- Tne slit contains a fast-l - or a device of locking type which is easy to open and close and which the closed position closes the slit hermetically so that an air-tight enclosed space 14 is obtained between the sheets 10, 12. At the bottom edge of the roller-blind a brace 6 is attached at external side of the sheet 12 closest to the window panes 26 in order hold the roller-blind 2 to the wall 24, for example by a hook attached to the wall- On the sheet 10 facing the room , preferably at its middle porti and directly above the brace 6 a catch 22 is installed, suitably in th form of a flap of the same material as the sheet, in order to ensure i simple way the separation of the sheets 10, 12 for filling the space w air. When the roller-blind 2 is rolled up on the curtain rod 4 the sheets 10, 12 lie. close to each other and the valve 8 is open. To use blind it is pulled down and attached by means of the brace 6- Then the grasping device is grasped and the sheet 10 is pulled away from the attached inner sheet 12, whereby air flows through the opened valve 8 into the space 14 between the sheets When the required amount of air flowed in, the valve 8 is closed whereby a non-circulating and thus effective heat-insulating air layer of substantially atmospheric press is obtained in the space 14. When rolling up the blind 2 the valve 8 i opened first so that the air may escape during the rolling-up In orde to make the blind rapid and convenient to use it has proved necessary practice to have a valve which in its open position has a large openin for the inflow and outflow of air when the sheet 10 is pulled away fro the sheet 12 and when the blind is rolled up, respectively. The slit therefore extends along a considerable portion of the bottom edge of t blind- Suitable the roller-blind 2 is attahced to the curtain rod by attaching the upper edge of the sheets 10. 12 with double-adhesive tape on the rod of the roller-blind. As seen in Fig. 1 the roller-blind 2 is somewhat wider than the window, suitably 10-20% wider. The air-filled blind 2 is normally so elastic that it adjoins wit good air-tightness to the contact surfaces around the window when it is attached bv the brace 6. In this manner, a further non-circulating, heat-insulating air layer 28 is obtained between the blind and the wind pane 26. If the embrasure of the window or its linings do not have smooth, straight surfaces the blind 2 can still be brought to good contact by using a holder 30 above the blind, for example in the form of a hook, a stretch a band or a string over the blind to a holder 32 below the blin In this manner the air-filled blind is pressed by means of its elastic until good contact is achieved even against uneven contact surfaces. A drying agent is suitably placed between the sheets in the blin in order to prevent a build-up of condensation. Furthermore, the sheets are suitably treated to be antistatic so that no air-suspended particles cling to the sheets. In order to enable the installation of a roller-blind according the invention also on the outside of a window the sheets should suitab be made of a material which is resistant to ultraviolet radiation- In an alternative embodiment the braces at the lateral edges of blind may be replaced by a tightening device attached to the wall.

Claims: Claims 1. Heat-insulating roller-blind intended to be placed in front o windows, characterized in that the blind consists of two thin, transparent, hermetic, congruent sheets which in their outer edges are hermetically joined to form an enclosed space, and that a valve is arranged, to enable, in its open position, admission to said space of room air, a non-circulating, heat-insulating air layer of substantiall atmospheric pressure being obtained between the sheets upon closure o - the valve, and in the open position of the valve outflow of air from s space being allowed when pulling up the blind. 2. Heat-insulating blind according to claim 1, characterized in that additional sheets are installed in order to form additional space so that by filling with air through additionally installed valves seve heat-i ' nsulating spaces are formed. 3. Heat-insulating blind according to claim 1 or 2, characterized by attaching devices for securing air-tight connection between the air filled blind and the window embrasure or window linings, so that a basically non-circulating, heat-insulating air layer is obtained betwee the window and the rolling-blind. 4. Heat-insulating blind according to any of claims 1 through 3, characterized in that the sheets consist of a stiff but flexible material, and in that the joining of the outer edges of the sheets is elastic in a manner .capable of absorbing the displacement between the sheets when the blind is rolled up on the curtain rod. 5. Heat-insulating blind according to claim 4, characterized in that the elastic joining consists of elastic border bands of a width capable of absorbing the expansions between the sheets when the air is admitted between these sheets. 6. Heat-insulating blind according to any of claii__s 1 through 5, characterized in that the valve is designed as a slit valve located at the bottom of the blind, which valve, when the blind is to be rolled up. can be opened to such a width that the air contained therein can flow o rapidly while the blind is rolled up on the curtain rod. 7. Heat-insulating blind according to any of claims 1 through 6, characterized in that means are arranged to enable separation of the sheets in the pulled-down position of the blind for suction into the closed space of room air through the opened valve. 8. Heat-insulating blind according to any of claims 1 through 7, characterized in that the sheets consist of a plastic material which do not melt* at a contact with an electric radiator. 9- Heat-insulating blind according to any of claims 1 through 8, characterized in that a drying agent is placed between the sheets in order to counteract the building-up of condensation. 10. Heat-insulating blind according to any of claims 1 through 9, characterized in that the sheets are anti-statically treated.

Inventors: LILJENDAHL SVEN A
Applicants: LILJENDAHL SVEN A
Application year: 1981
Main classification: E06B9
IPC codes: E06B3, E06B9