The present invention relates to heat insulating glass pane elements of the triple or multiple type, i.e. of the type in which at least three glass plate members are mounted in parallel relationship slightly spaced from each other by means of spacer members along the edge portions of the glass plate members, the assembly being sealed along the edge surfaces such that the spaces confined between the respective pairs of neigh¬ bouring glass plate members are closed spaces contain- ing a clean and dry gas, normally ordinary atmospheric air. As-in usual double layer panes the gas or air will hereby remain dry, and it is endeavoured to pro¬ vide an extremely tight sealing of the said spaces, almost amounting to a really hermetic sealing, because it must be anticipated that the pane element should be usable during a very long period of time without showing intolerable condensation problems due to in¬ trusion of humid air from the surroundings.

On the other hand it is desirable to achieve the said sealing in a very simple manner, normally merely be means of a bonding and sealing compound applied to the edge portion of the pane element, i.e. without the pane element being provided with any rigid frame con¬ struction of its own. Therefore the pane elements should also for this reason be protected against heavy mecha¬ nical influence.

Now, in an ordinary double pane element with only one space between the single pair of glass plate ele¬ ments there may well occur some mechanical stress due to the fact that the two glass plates may be subjected to mutually different temperatures and additionally due

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to the fact that the average temperature of the volume of gas or air as trapped in the space between the glass plates may undergo temperature variations and therewith variations in the internal air pressure of the pane element. According to general experience through many years the- said double pane elements may resist these influences when they are made with a reasonably high quality.

However, when the pane elements are produced with three or more glass plate members there is a tendency towards increased sensibility of the elements, this probably for a large part being due to the fact that more than one air space is provided, i.e. the element is divided in zones which will often show mutually different temperatures; one important consequence is that the air or gas in the two or more respective closed spaces will show mutually different gas pressures, which may result in the glass plates curving in mutual¬ ly different degrees or ways, which is visually no- ticeable,just as even breaking of the glass may occur. For the same reason, a production of multi-layer thermo panes of which the shorter side is less than 80 cm is generally non-recommendable, while by ordinary double panes the shorter side can be as short as 20 CE. In a multi-layer pane the outer air space will be subject to much greater temperature variations than those occur- ing in the single air space in a double-layer pane, while the inner air space to a larger extent will assume the more stable room temperature. It has been considered to provide for an inter¬ connection between two adjacent spaces in such elements by drilling a hole in the glass plate element forming the partitition therebetween, whereby a gas pressure equalization and a counteraction of the mechanical stresses is obtainable, but from a production point of view this is a difficult measure, and the hole drilling in fact involves a weakening of the particular area of

the intermediate plate element.

It is the purpose of the invention to provide for a triple or multiple glass pane element in which a gas pressure equalizing connection between two of said gas or air spaces is obtained in an easy and advantageous manner.

According to the invention the said connection is established by means of a narrow tube element which ex¬ tends from one space into the other about an exterior edge portion of the intermediate glass plate member, totally or partially embedded in the edge-sealing com¬ pound, the intermediate glass plate preferably being of the same size as the other glass plates in the pane. With the use of such a tube member, which may be very narrow indeed, it is possible to establish a flow con¬ nection between the said two spaces without in any way preparing the intermediate glass plate member by hole drilling or- notch cutting, since the connection tube may simply extend across the edge of this plate member with- out generally changing the overall exterior dimensions of the pane element. In a triple pane element it is, with respect to both production and stability, highly desirable that all three glass plate elements are of the same overall dimensions and are placed in the pane element so as to have their edges located in respective common planes, whereby the addition of a tube member crossing the edge of the middle plate member could well give rise to a considerable increase of one main di- mension of the pane element, and moreover, by handling and mounting of the element, the tube could cause damage to the intermediate glass plate by transferring exterior mechanical forces thereto. When the tube is narrow, how¬ ever, as it may well be for the discussed purpose, this increase of dimension will be almost neglectible, and besides the crossing tube portion will be more or less embedded in tie sealing compound layer applied to the respective edge portion of the pane element, whereby

the tube hardly or not at all will be exposed outwardly. When the pane element is handled reasonably carefully, therefore, the tube member will not be liable to be ad¬ versely affected, and in the mounted position of the pane element the tube member will not either be subjected to overcritical pressure forces during the long period of use, because there is normally a free mounting space outside the top and lateral edges of the pane element, where the tube is preferably located, while bottomwise the pane element is supported by non-rigid carrier mem¬ bers.

In the following the invention is described by way of example with reference to the accompanying- drawing, in which:- Fig. 1 is a perspective view of a corner portion of a thermo pane according to the invention, while

Fig. 2 is a more detailed cross sectional view of an edge portion of the pane.

Generally the illustrated pane element is of well known construction. It comprises three glass plates 2, 4 and 6 mounted in parallel spaced relationship as de¬ fined by profiled spacer members 8 arranged between the edge portions of the respective pairs of glass plates. The spacer members 8 form respective closed frame structures, and they are hollow and provided with perforations 10 in the wall portions thereof facing the respective interior spaces of the pane element. Normal¬ ly there is deposited in the interior of at least the lowermost spacer members a material capable of absorbing any rest of humidity in the air or gas filling the associated interior space in the pane element.

The elements of the triple pane element are glued together and the outer edge surfaces are coated by a compound layer 1.2 intruding into outermost lateral spaces 14 between the glass plates and the respective spacer members.

Now, according to the present invention there is

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provided a narrow connector tube 16 extending across the upper edge of the middle glass plate 4 and being bent downwardly at both ends so as to project through predrilled holes 18 in the top sides of the neighbouring spacer members 8. The ends of the tube 16 do not break through the lower or inner sides of the spacer members, but since these sides are perforated the tube 16 will nevertheless constitute a pressure equalizing connection between the two pane element spaces in question. The exposed portion of the tube 16 will be at least par¬ tially embedded in the compound layer 12, when such a layer is used, and hereby the tube will be protected and the holes 18 will be sealed without requiring extra sealing measures. The tube 16, which may be made of copper, may be very narrow indeed, e.g. with an exterior diameter of the magnitude 1 mm, preferably 0.75 mm with an interior diameter of 0.55 mm, because its purpose is to equalize the pressure in the two pane element spaces during a relatively long period of time, and with the sufficient small thickness of the tube.there will be no considerable problems resulting from the tube member constituting a protrusion from the edge of the pane element, par¬ ticularly not with the use of a compound layer 12 cover- ing the tube member.

However, if desired, an intermediate glass plate 21 can be used, as shown in Fig. 2, the relevant edge of which is located retracted relative the edges of the outer plates, so that all of the tube 16 can be mounted inside the outer edge of the ther o pane. A similar retracted location of the tube 16 may be achieved by cutting a small transverse recess in the edge of the intermediate plate 4, which will not necessarily weaken this plate substantially. However, these alternative solutions will of course be definitely unattractive from a production point of view.

It will be appreciated that the invention is not

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limited to thermo panes of the construction exactly as shown in the drawing, as it is of no importance to the invention how the elements in the thermo pane are assembled.

It may be sufficient for thermo panes with more than two air spaces that a pressure equalizing connection is provided between only two of the spaces.