WO1999045225A1

WO1999045225A1 - A window comprising an insulating pane and a frame, a method of producing such a window, and a valve for use in carrying out the method

Info

Publication number: WO1999045225A1
Application number: PCT/DK1999/000104
Authority: WO
Inventors: Eik Bezzel Hansen; Ivar Moltke
Original assignee: Dansk Teknologisk Institut
Priority date: 1998-03-03
Filing date: 1999-03-03
Publication date: 1999-09-10
Also published as: AU2611699A; DK28199A

Abstract

The window comprises an insulating pane (1) and an integrated evacuated frame (9) which completely or partially replaces the ordinary frame of the window. The integrated evacuated frame increases the total insulating property of the window by breaking the heat transmission through the edge and the frame. The window is evacuated through a valve (13) which can seal the window at room temperature whereby the outgassing from melted material into the permanently sealed portion of the window is reduced.

Description

A window comprising an insulating pane and a frame, a method of producing such a window, and a valve for use in carrying out the method.

The present invention relates to a window comprising an insulating pane and a frame connected with the pane along its edge zones, in which the insulating pane comprises at least two glass plates in mutually spaced relationship, in which between adjacent glass plates there is provided an essentially sheet-shaped spacer member with a plurality of spacer elements in abutment with each adjacent glass plate, in which along the peripheries of said insulating pane an edge sealing is provided such that at least one coherent cavity is formed between each spacer member and each of the adjacent glass plates, and in which a vacuum is provided in said cavity or cavities.

Vacuum windows have been described in patents since the beginning of this century. These previous inventions are characterised by two layers of glass being sealed in a gas-tight manner along the edges and separated from each other by spacer elements evenly spaced over the area. The interspace thus created is evacuated through a hole or a valve which are sealed in a gas-tight manner when the desired pressure is obtained. The two layers of glass can be provided with low emissivity coatings on one side of the glasses facing the vacuum. The spacer elements are typically spaced in a square pattern with a distance of 20-40 mm and are usually made of hard materials. Such products are described among other in the published international patent applications WO 91/02878 and WO 93/15296, just as such products have been commercially available since the beginning of 1997. In order to improve the insulating property of the pane and to simplify the production, WO 94/24398 discloses an insulating panel, e.g. a vacuum or evacuated pane corresponding to the initially mentioned insulating pane where the spacer elements are provided on a coherent dividing plate .

Evacuated windows are distinguished by having a considerably better thermal insulating property than non-evacuated double or triple glazed windows. The insulating property of a two-layer evacuated pane, where both glasses on the side facing the vacuum is provided with a low emissivity coating which reflects

2 long-wave radiation, is about 0.7 W/m K, which is to be compared with the U-value of double or triple glazed thermo panes of about 1.9 W/m 2K and 1.1 W/m2K, respectively. Evacuated windows are furthermore lighter than triple glazed windows and substantially thinner than both double and triple glazed thermo panes . A further advantage of evacuated panes is that due to the need for low outgassing and an important temperature resistance during the production, they are made of materials affected only to a small extent by the weather, which is an obvious improvement compared to generally known thermo panes which usually contain organic materials, e.g. butyl sealing rubber decomposable by contact with UV radiation and moisture. However, the structure of the conventional vacuum pane is conditioned by a limitation of the thermal insulation property of the product because the edge sealing creates a mechanical contact between the two layers of the pane along its edge . To this must be added that even the modern window frames intended for both evacuated and non-evacuated windows are often considerably lesser insulating than the pane itself. DE patent no. 195 37 459 discloses a frame structure where in order to obtain an improved insulation property in cavities in the frame, a gas with a heat transmission property lower than air is injected, or where a vacuum is provided in the cavities. This solution, however, does not remedy the problem with thermal bridges along the edge sealing.

US patent no. 5,005,557 describes an evacuated pane composed in such a way that the edge sealing is constituted by a flexible metal film hermetically sealed to both glasses and designed in thin metal foil in order to obtain a considerable flexibility and a low heat transmission. However, this document describes a rigid frame in relatively thick metal or plastic which can be used as frame for the window.

The object of this invention is to provide a window of the initially stated kind which to a considerably extent reduces the heat loss to the surroundings in comparison with window known so far. This purpose is fulfilled in that the window according to the window is characterised in that said frame comprises at least one cavity and that the frame is connected with the insulating pane in such a way that the cavity or cavities of the frame is in a direct connection with the cavity or cavities of the insulating pane, the connection between the frame and the insulating pane constituting said edge sealing.

In this design, the frame constitutes an integrated highly insulating part of the window as the evacuated frame forms an extension of the vacuum cavity and creates an evacuated insulation around the edge of the pane. The frame thus replaces completely or partially a conventional window frame, whereby the heat loss through the frame is reduced considerably, as the frame of the window contains a thermally insulating vacuum and at the same time the loss through the edge of the window itself is also reduced. This is particularly advantageous for windows mounted in roof tiles where the plane of the window is raised above that of the roof and thus raised essentially above the plane of the roof insulation to assure the water tightness of the window. The integrated highly insulating evacuated frame insulates the area between the plane of the glass and that of the roof insulation which in roof windows is often of the same size as the pane itself and thus fully determines the insulation of the window. The volume of the frame can e.g. also be used for positioning a molecular getter acting on the cavity of the frame or the entire window. In an embodiment being advantageous as to production and mounting, this frame constitutes the frame of the window itself.

In another aspect of the invention, a method is provided for producing a window according to the invention.

In a further aspect a valve is provided, by which the evacuation of the window can be effected by sealing the valve at room temperature and possibly later by an additional sealing on the exterior. This is advan- tageous compared with the production of conventional vacuum panes where the evacuation valve of the pane is sealed by melting glass or metal in the opening itself. Thus, an outgassing takes place from the melted metal of gasses absorbed herein. As this outgassing takes place in the very sealing moment, this implies a pollution of the achieved vacuum in the pane. By the present invention, the vacuum of the pane is improved and thus the insulation property and at the same time the sealing method is simpler and less expensive. Further advantages of the present invention will appear from the dependent claims .

The invention will in the following be described in more detail with reference to the schematic draw- ings , where

Fig. 1 shows an exploded view of a known insulating pane,

Fig. 2 is a sectional view on a large scale of the pane shown in Fig. 1, Fig. 3 is a sectional view corresponding to Fig. 2 of an embodiment of a window according to the invention,

Fig. 4 is a perspective view showing the window shown in Fig . 3 , and Fig. 5 is a sectional view on a large scale along the line V-V in Fig. 4 of a valve for use in the production of a window according to the invention.

Figs . 1 and 2 show the f ndamental structure of an insulating pane 1 in the form of a vacuum or evacu- ated pane. The insulating pane 1 comprises in the shown embodiment two layers of glass 2, 3 mutually spaced and constituting the outer glasses of the insulating pane, and a dividing sheet generally designated 4 provided in the interspace between the two glasses 2, 3 and which constitutes a spacer member for the glasses 2, 3. An edge sealing 7 is provided along the periphery of the pane 1 such that an evacuated cavity 8 is created in the glass interspace. The dividing sheet 4 is designed as a coherent plate 5 provided with exactly placed and formed elevations

6 in the following called knobs positioned on both sides of the plate such that these knobs 6 constitute the thermal and mechanical contact to the outer glasses 2, 3 of the pane . The use of a coherent dividing sheet 4 entails that the pane 1 serves as a three-layer vacuum pane, where the insulation property is about the double of that of a conventional vacuum pane. The dividing sheet 4 can be provided with low emissivity coatings at one or more sides which contributes to the reduction of the radiation transmission between the outer faces of the window. The dividing sheet 4 may replace the production, positioning and fixation of conventional spacer elements, and the dividing sheet 4 being merely one component, it may be cheaper than by the previously known technology where about 1000 spacer elements are to be provided per square meter. This embodiment may also lead to a more correct production as the dividing sheet 4 can be cast in one form and therefore reproduced in a precise and considerably sure manner. The probability of spacer elements missing on some positions in the window is thus reduced: an error which in the case of separate spacer elements may lead to overloading of the neighbouring spacer elements and hereby lead to destruction of all spacer elements in the window.

The dividing sheet 4 can be produced of transparent, opaque or non-transparent material depending on the function of the window. The dividing sheet is produced from a material which can stand use in high vacuum including in particular that the outgassing, vapour pressure and permeability of the material are sufficiently low in order to assure the existence of an insulating vacuum in the product. Examples of such suitable materials are glass, ceramics, metals or composites hereof. The dividing sheet 4 may be provided by one or a combination of the following different processes:

1. Cast in a form made of inorganic, heat-resisting material. The form is designed as two negative casts of the desired shape of the form and the melted glass is cast in this form. The demoulding takes place in a conventional way and subsequently, the dividing sheet is reheated to remove tensions generated during the moulding process. The moulding process may have starting point in melted glass. Alternatively, the float glass is melted directly in the form.

2. Etching or engraving of materials from the service such that the described shape appears .

3. Spacer elements, e.g. hard ceramic spacer elements in e.g. ball shape, can be positioned in the form such that the spacer elements having larger thickness than the dividing sheet are provided in the recesses of the form. When the other side of the form is also mounted, the spacer elements are sandwiched between both sides of the form. The glass plate is then cast such that it surrounds all spacer elements and retains them. The spacer elements can be positioned by the balls rolling in place when the plate is shaken or by placing a ball in each field in a grid whereafter the grid is moved a grid width in both directions of the grid. All spacer elements are thus positioned in the same corner of the grid fields and thereby exactly opposite the recess. If the grid is heated, the spacer elements slip from the grid and fall into place in the recess in the form.

4. Cast as gel e.g. produced by alcoxide method or as particular sol gel. The cast is made in two form halves each describing a negative of the desired shape of the spacing plate. After gel formation, the gel is strengthened by adding fresh sol with compatible composition. The wet gel is dried in a controlled environment and sintered to complete density by heating in an oven.

5. Whereas the evacuated glass construction need not to be transparent, the dividing sheet can be 8 designed in a metal plate where the projections are obtained by pressing bulges in the metal plate or by making bulges on the plate in the same or harder material . Irrespective of the chosen production method, the dividing sheet can subsequently be covered by a low emission coating on at least one side according to generally known techniques.

Besides keeping the glasses 2, 3 in mutual distance, the heat loss of the pane itself is reduced by using a coherent dividing sheet, and the process is considerably simplified in relation to production of conventional evacuated windows.

As an alternative, the pane 1 can comprise an outer glass corresponding to the one described above, and which e.g. can be of conventional float glass, and a dividing sheet which on the side facing the first outer glass is provided with space-keeping knobs such that the spacer plate forms the second outer glass in a two-layer pane.

An embodiment of a window according to the invention will be described with reference to Figs. 3-5 where elements with the same or analogue function as the elements which were used in the description of Figs. 1 and 2 will generally have the same reference number .

The insulating pane 1 is here connected with a frame generally designated by 9. The frame 9 is formed by one or more hollow profile elements and can, as it will be explained in the following, either be constituted by an entire coherent frame or be assembled by separate frame elements to form an essentially rectangular frame.

The outward facing or outer glass 2 in the mounted position of the window is connected to the frame 9 at outer edge flanges 10 projecting inward, and the inner or inward facing glass 3 is connected to the frame 9 at corresponding inward facing inner edge flanges 11. The connection between the insulating pane 1, the glasses 2, 3 and the frame 9 is made in a gas- tight manner as described more detailed in the following such that in the shown embodiment, one hermetically sealed, coherent cavity is formed to comprise the cavity 8 provided in the interspace between the spacer plate 4 and each of the glasses 2, 3 and the cavity 12 provided in the frame profile elements.

The frame 9 constitutes thus an integrated part of the insulating pane 1 and designed such that besides forming a part of the edge sealing between two said layers of glasses 2, 3, can also completely or partially form the frame of the window.

The integrated frame is produced of a material with properties which are suitable for high vacuum applications, including modest outgassing and permeability, possible hermetical sealing to the outer glass of the window, resistant to the temperatures to which the product is exposed both during ordinary use and during production and possible shaping to the described form with the distance between the edge flanges 10 and 11 adapted in such a manner that the knobs 6 of the dividing sheet 4 are in contact with the inner side of the glasses 1 and 3. Suitable materials can be e.g. stainless steel, in particular including austenitic stainless steel of the type 304L and 316 , nickel, aluminium, copper, their alloys or other mixtures hereof. If the frame is based on materials of above type and characteristics, it can be produced by one of the following production processes or combinations hereof: 10

1. Deep-drawing of a coherent plate where the middle is removed by die-cutting or a similar operation thus providing a coherent frame which towards the glass face ends in two plane faces to which the joining with glasses can be made.

2. Rolling or folding of profiles which are subsequently cut in appropriate lengths or a similar method and thus form the entire frame as described above . Alternatively, the frame can be produced by a composite material e.g. consisting of plastic and metal, orientated such that the metal is facing the vacuum side of the product whereas the supporting portion of the frame is constituted by plastics. By such materials, almost the same vacuum tightness as by pure metals is obtained, but at the same time, the weight of the components are saved just as the production costs can be smaller. In cases with such materials, the frame is produced by the following method.

1. Deep-drawing of a metal/plastics composite consisting of stainless metal foil laminated to generally known construction plastics, e.g. polypropylene. This composite can be formed by folding or drawing such that profiles or a readily formed frame can be formed as described under above points 1 and 2. In both cases, the frame is shaped such that the metal foil is facing the glasses on the surface where the sealing between the frame and glass is to take place. It is thus assured that the plastic component is not brought into contact with the evacuated cavity where the outgassing from this material can take place.

Whether the frame is produced from homogeneous materials or composites as described above, the frame insulation can obtain sufficient strength against 11 atmospheric pressure by different mechanisms e.g. that the material itself is sufficiently thick, that it is shaped such that the form contributes to the strength, that the face in the process is provided with knobs as described for the spacer plate above, or combinations of these three solutions.

The inner and outer glasses 3, 2 are assembled by the dividing sheet 4 as separation and these three elements are placed in the ready-formed frame 9. The hermetical sealing of the two outer glasses 2, 3 to the frame 9 can be effected by one of the following sealing methods.

1. The sealing is effected by placing a soldering paste of particular gel particles where the diameter of the particles is smaller than 100 nm and the composition of the particles is adapted to physical and chemical properties of the glasses and of the frame, on the flat portion of the frame, i.e. the edge flanges 10, 11 facing the glasses 2, 3. This soldering paste is brought into tight sealing by heating. The advantage of using gel particles is that the densification can be effected at a lower temperature than usual which compared to the use of e.g. tempered glass in the window implies less stress relieving of this prestressing.

2. The finished shaped profile is sealed to the two glasses according to the same method as when producing conventional evacuated windows by use of soldering glass, soldering alloy or alike. 3. A second assembling method and including soldering with or without external supply of material or soldering assembly or use of other soldering materials, e.g. generally known tin solder or other materials suitable for this purposes can be used. 12

The evacuation of the window can be effected as by evacuation of conventional evacuated panes or by a two- step sealing valve 13 where the outgassing into the permanently sealed part 8, 12 of the window is reduced. When producing conventional vacuum panes, the evacuation valve of the window is sealed by melting glass or metal in the opening itself. An outgassing is thus effected from the melted metal of gasses absorbed in this. As this outgassing is effected in the very sealing moment, this means a pollution of the obtained vacuum in the pane .

In the shown embodiment, the valve 13 for a so- called cold sealing comprises a valve mantle 14 of a material which is suitable for use in high-vacuum products, e.g. stainless steel of the type 304L or 316L and a valve seat 15 connected to the frame 9 at an assembly face 18 and with an outward facing nosing or a boss 16. The valve mantle 14 can be provided with a thread 17 for connection with the valve seat 15, e.g. when turning the valve seat 14 by means of a suitable tool inserted in a hexagonal hole 22. The valve seat 15 can advantageously be produced of the same material as the valve housing 14, however, this is no necessity as it has no direct access to the permanently sealed portion of the window. Between the valve mantle 14 and the valve seat 15, there is provided a gasket 19 of a soft and ductile material suitable for use in high vacuum applications. This might e.g. be pure copper, indium, gold or alike. Subsequent to the evacuation via an evacuation hole 21 in the valve mantle 14, the valve is sealed in the following manner. At the first sealing stage, this soft gasket 19 is pressed or squeezed in a gas-tight way against the valve seat 15. To assure a longer durabil- ity of the sealing, the valve can be supplemented by an 13 extra sealing on the outside. A ring 20 of an appropriately selected soldering material is provided in the valve seat 15 near the gasket 19. When heating the exterior of the valve, this soldering material is melted, thus floating around the gasket 19 when wetting the valve mantle 14, and forming a further sealing of the gasket of the valve against the valve seat . The latter can be designed under vacuum or by atmospheric pressure. The valve can subsequently be reopened for re-evacuation of the window, e.g. in connection with control of the production or alike, and can be sealed again after above procedure, merely by adding a new gasket .

The valve is thus designed as a special metal/- metal evacuation valve where the airtightness is obtained by squeezing a softer metal between two harder ones or a soft one down into a hard one or vice versa where the valve is supplemented by a melted two-step sealing on the exterior. The evacuation and sealing process is carried through by microwave technology at a lower temperature such that outgassing against vacuum is reduced.

It is understood that the frame 9 may comprise several closed cavities each connected to a valve. The window according to the invention is, besides being intended for use in connection with the construction, mounted in a wall, roof or another construction component, e.g. also usable for mounting on all other places where a highly insulating window may be desir- able, including automobiles, boats, ships, aeroplanes or other .

Claims

14P A T E N T C L A I M S

1. A window comprising an insulating pane (1) and a frame (9) connected with the pane along its edge zones, in which the insulating pane (1) comprises at least two glass plates (2, 3) in mutually spaced relationship, in which between adjacent glass plates (2, 3), there is provided an essentially sheet-shaped spacer member (4) with a plurality of spacer elements (6) in abutment with each adjacent glass plate, in which along the peripheries of said insulating pane (1) an edge sealing is provided such that at least one coherent cavity (8) is formed between each spacer member (4) and each of the adjacent glass plates (2,

3), and in which a vacuum is provided in said cavity or cavities (8) c h a r a c t e r i z e d in that said frame (9) comprises at least one cavity (12) and, that the frame (9) is connected with the insulating pane (1) in such a way that the cavity or cavities (12) of the frame is in a direct connection with the cavity or cavities (8) of the insulating pane, the connection (10, 11) between the frame (9) and the insulating pane (1) constituting said edge sealing.

2. A window according to claim 1, c h a r a c t e r i z e d in that said frame (9) constitutes the frame of the window.

3. A window according to claim 1 or 2 , c h a r a c t e r i z e d in that the frame (9) is formed by hollow profile elements with inward projecting outer and inner edge flanges (10, 11) which are connected to the outer and inner, respectively, glass plate (2, 3) . 15

4. A window according to claim 1, 2 or 3, c h a r a c t e r i z e d in that the outer glass plate (2) of the insulating pane (1) has larger dimensions in the plane of the insulating pane than the inside situated glass plate or plates (3) .

5. A window according to any of the claims 1-4, c h a r a c t e r i z e d in that said frame (9) is produced of metal, preferably stainless steel.

6. A window according to any of the claims 1-4, c h a r a c t e r i z e d in that said frame is produced of a composite material, preferably comprising a plastic material.

7. A window according to claim 6, c h a r a c t e r i z e d in that the frame on the side facing the cavity of the frame is covered with a metal foil.

8. A window according to any of the preceding claims, c h a r a c t e r i z e d in that the frame comprises stiffening means.

9. A method of producing a window according to any of the claims 1-8, comprising the following steps: providing at least one essentially sheet-shaped spacer member (4) with loose or integrated spacer elements (6) , providing a frame (9) with at least one cavity (12), positioning two or more glass plates (2, 3) above each other with a spacer member (4) inserted between adjacent glass plates to form an insulating pane (1) with at least one cavity (8) , placing the insulating pane (1) in the frame (9) , c h a r a c t e r i z e d in that the insulating pane (1) is connected to the frame (9) in such a way that the cavity or cavities (8) are brought into direct connection with the cavity or cavities (12) of the frame, 16 that the insulating pane (1) and the frame (9) are assembled in an essentially gas-tight edge sealing, and that a vacuum is provided in said cavities (8, 12) by evacuating through at least one valve (13) which is subsequently sealed.

10. A method according to claim 9, c h a r a c t e r i z e d in that the sealing of each valve (13) takes place in two steps .

11. A method according to claim 9, c h a r a c - t e r i z e d in that the first sealing step comprises a compression of at least two different metals with mutually different hardness.

12. A method according to claim 10 or 11, c h a ra c t e r i z e d in that the second sealing step comprises melting of a gasket material.

13. A valve (13) for use in carrying out the method according to any of the claims 9-12, comprising a valve mantle (14) and a valve seat (15) which are meant to be brought into mutual abutment, c h a r a c - t e r i z e d in that the valve (13) also comprises a gasket (19) provided between the valve mantle (14) and valve seat (15) , and which by sealing is meant to be compressed between them.

14. A valve according to claim 13, c h a r a c - t e r i z e d in that the gasket (19) is made of a soft and ductile material, such as copper, indium or gold.