Prior art describes openable fire-retardant windows in which a pane is retained between an outer sash in the form of an aluminium profile and an internal glazing bead fastened thereto in the form of a solid wooden bead. In the closed position of the window, the wooden bead together with swellable, fire- retardant material provided on both sides thereof fills the space between the pane-and a solid wooden frame in which the sash is swingably hung. The solid wooden bead and wooden frame efficiently retard penetration of flames around the edge area of the pane, because wood burns away very slowly in relation to many other materials, particularly substantially slower than known plastic materials.

However, in the known window it is a disadvantage that the machining of the wooden bead to the desired shape is work-intensive, as the bead has to be milled out to make room for the fire-retardant material and to be able to fit together with the aluminium sash. Furthermore, the mounting of the bead is labour-intensive, as it is necessary to seal manually with fire-retardant silicone between the bead and the pane. To obtain the desired fire- retardant effect, the bead furthermore has to be rather voluminous and thus covers so much of the edge area of the pane that the visible area of the pane is reduced to an undesired high degree. To hide the high wooden bead in the closed position of the window, it has been necessary to increase the height of the frame to an undesired high degree.

The object of the present invention is to provide a fire-retardant window that allows simpler manufacturing and mounting of the glazing bead and provides a good fire-retardant effect.

In view of this, the window according to the invention is characterized in that the glazing bead is manufactured from at least partially synthetic material and at least partially encloses a longitudinal cavity.

It is substantially easier to shape a synthetic material into a specific shape than a wooden bead, as the material can be shaped to its basic shape without cutting, for example, by moulding. In this way, the glazing bead can easily be shaped with slots or grooves that allow the use of pre-manufactured sealing strips with a fire-retardant material, which also obviates manual sealing with silicone and thus considerably facilitates mounting of the bead.

Furthermore, the bead can be formed with suitable engagement means for easy mounting of the bead on the sash without any extra machining.

When influenced by a high temperature at fire, the synthetic material is softened, and the fire- retardant material at the bead swells while completely or partially filling the cavity of the bead, and the two materials thus combine to form a coherent string that swells between the pane element and the frame and has proved thereby to be able to retard penetration by flames for just as long as the known glazing bead of solid wood, and this even with a bead with a smaller cross-section than the known wooden bead. It has therefore surprisingly been found that a synthetic material which, in itself, burns down extremely rapidly can advantageously be used together with a swellable, fire-retardant material for the manufacture of the glazing bead for the window.

In a particularly advantageous embodiment in terms of manufacturing, the glazing bead is formed as an extruded moulding.

In an advantageous embodiment, one or more strips of the swellable, fire-retardant material are at least partially enclosed by the glazing bead. This ensures good retention of the fire-retardant material at the right place during its swelling so that the material is prevented from possibly falling out of the space between the pane and the frame where the fire-retardant barrier is required.

In a further advantageous embodiment, one or more strips of the swellable, fire-retardant material extend in an internal closed channel in the glazing bead. Thus, after filling any cavity around itself in the bead, the fire-retardant material can distend the softened bead like a balloon and press the bead material out towards the pane and the frame, whereby the glazing bead is kept well in place in the space.

The glazing bead may advantageously comprise a first internal channel extending immediately within a sidewall of the glazing bead, said sidewall being exposed at the inner surface of the closed window, and a second internal channel extending next to the first channel and opposite to the exposed sidewall, and the first channel may be empty and the second channel may contain a strip of the swellable, fire- retardant material. In this way, flames coming from the inside will first heat the exposed sidewall and then the partition between the two channels, and the empty channel will therefore act as an insulator so that the heating of the neighbouring channel, which contains a strip of fire-retardant material, will take place suitably gradually so that the fire- retardant material will have time to swell vigorously and expand the glazing bead before the material of the glazing bead is so heated that it may not in itself be able to keep the fire-retardant material in place.

The glazing bead may advantageously comprise a substantially U-shaped section the opening of which faces an inwardly projecting flange portion of the outer sash and which is retained in a groove in this flange portion. This facilitates insertion of a strip of fire-retardant material in a channel of the glazing bead, as the strip can be inserted in the U- shaped section from the open side thereof before the glazing bead is mounted on the flange portion of the sash. Furthermore, it allows easy integration and thus hiding of a locking mechanism for the window in the glazing bead, as this mechanism can be inserted in the cavity of the U-shaped section and engage with a striking plate on the frame through a recess in the flange portion of the sash.

A strip of the swellable, fire-retardant material may adhere along an inner surface of the U- shaped section of the glazing bead, whereby the strip is kept separate from any locking mechanism in the cavity.

A sealing strip comprising a strip of the swellable, fire-retardant material may be wedged between the pane and the glazing bead.

A sealing strip may be inserted in a groove in the glazing bead between the glazing bead and the frame, and a strip comprising a strip of the swellable, fire-retardant material may be inserted in a groove in the sash between the sash and the frame.

In an advantageous embodiment, the glazing bead in its mounted position on the sash forms at least two separate closed channels, a strip of the swellable, fire-retardant material extending in each channel, and a strip of the swellable, fire-retardant material extending between the pane element and the glazing bead, between the pane. element and the sash, and between the sash and the frame. This ensures a good distribution of the fire-retardant material in and around the glazing bead, and the interaction between the bead and the fire-retardant material is therefore particularly good at heating and swelling thereof.

The present invention further relates to a glazing strip for mounting between a pane element and a glazing bead in a fire-retardant window of the type described above. The glazing strip is characterized in that it is made by co-extrusion of a first strip of substantially solid synthetic material and a second strip of swellable, fire-retardant material and is formed substantially as shown on the sole figure of the drawing. The advantages described above will thus be obtained.

The invention will now be described in more detail below by means of examples of embodiments with reference to the schematic drawing, the sole figure of which shows a cross-sectional view of a fire- retardant window according to the invention.

In the embodiment shown, a sealed double glazing pane 1 comprises an external glass pane 2 mounted at a distance from an internal glass pane 3 by means of a distance profile 4 inserted between the panes at an edge area 5 thereof. At its edge area 5, the double glazing pane element 1 is mounted in a window sash formed by an extruded aluminium profile 6. The aluminium profile 6 has a first flange 7 extending at a distance from and in parallel with a peripheral edge surface 8 of the double glazing pane element 1, and a second flange 9, which extends at right angles to the first flange 7 and at a distance from and in parallel with an outer surface 10 of the external glass pane 2 of the double glazing pane element 1.

The flange 9 has a U-shaped section 11 open towards the double glazing pane element 1 and forming a countersunk groove 12, with which an outer glazing strip 13 engages, the glazing strip opposite to the groove 12 abutting the outer surface 10 of the double glazing pane element 1. The glazing strip 13 comprises a section 14 of relatively solid EPDM with wedge-shaped barbs pressed elastically into the groove 12 so that they grip under the countersinking of the groove, and a section 15 connected with the first section 14 and made of foamed EPDM abutting the double glazing pane element and thus absorbing tolerances between the sash 6 and the double glazing pane element 1, and the glazing strip 13 thus seals the connection between them in relation to the external environment.

The double glazing pane 1 is retained in the window sash 6 by means of an internal glazing bead 16 formed from an extruded plastic profile and mounted in engagement with the window sash 6. The profile 16 has a section 17 of a substantially U-shaped cross- section and being open towards a flange portion 18 in the form of a continuation of the first section 7 of the window sash 6, this flange portion 18 projecting inwards towards a window frame 19 made of solid wood and extending within and at a distance from the edge area 5 of the double glazing pane element 1. The U- shaped section 17 of the glazing bead 16 has foot sections 20,21 at its opening towards the flange portion 18, said foot sections engaging with two respective ribs 22,23 projecting towards each other on the flange portion 18 of the aluminium sash 6.

Between a rib 24 projecting from the glazing bead 16 at a corner thereof located opposite to the flange portion 18 of the sash 6 and facing the double glazing pane element 1, an internal glazing strip 25 has been inserted wedged between an inner surface 26 of the double glazing pane element 1 and the plastic profile 16. The internal glazing strip 25 comprises a strip 27 of solid EPDM which extends between the pane element 1 and the rib 24, absorbs tolerances between the double glazing pane element 1 and the glazing bead 16 and seals the space between these two parts against the internal environment, and a strip 28 connected with this plastic strip 27 and made of a swellable, fire-retardant material. This material 28 is thus located between the internal glass pane 3 and the glazing bead 16 and may, for example, be made of the material Pyroplex (registered trade mark), which may be manufactured to a swelling degree of up to 25 times the original thickness of the strip.

The two interconnected strips 27,28 of the glazing strip 25 may advantageously be made by co- extrusion. By integrating the sealing function and the fire retardant function in the glazing strip itself in this way, a particularly simple structure is obtained.

In an internal channel 29 in the plastic profile 16 enclosed by the U-shaped section 17 thereof, a strip 30 of the swellable, fire-retardant material mentioned above adheres on the side of the channel located nearest to the double glazing pane element 1.

The strip 30 may be delivered as a self-adhesive strip. The plastic profile 16 further encloses a channel 31 extending beside the part of the U-shaped section 17 facing away from the flange portion 18 of the aluminium sash 6 and approximately right between the inner surface 26 of the double glazing pane element 1 and a side 32 of the window frame 19 facing the double glazing pane element 1. In this channel 31, which has a smaller cross-section than the channel 29 formed by the U-shaped section 17, a loose strip 33 of the swellable, fire-retardant material has been inserted. In the profile 16, a further channel 34, which is slit by a slot 35 in its sidewall facing the window frame 19, extends between the channel 31 and the window frame 19, a resilient wedge 36 of a sealing strip 37 being inserted in the channel 35, which sealing strip 37 is of a type generally known and seals the glazing bead 16 in relation to the window frame 19 when the window is closed. Beside the channel 31, an empty channel 38 in the glazing bead 16 extends substantially in the area from the glazing strip 25 to the surface 32 of the window frame 19 and has a sidewall 39, one side of which is exposed to the inside room in which the fire-retardant window is mounted.

The flange portion 18 of the window sash 6 furthermore has a countersunk groove 40 facing the window frame 19 and in which a wedge-shaped section 41 of a strip 42 of fire-retardant material is mounted in firm engagement.

Furthermore, on the side of the window. sash section 7 facing the double-glazing pane 1, a strip 43 of swellable, fire-retardant material adheres right at the edge surface 8 of the internal glass pane 3. At right angles to the strip 43, a second strip 44 corresponding thereto and made of swellable, fire-retardant material is arranged, the strip 44 being fastened with part of its adhesive surface to a part of the edge area 5 of the inner surface 26 of the double glazing pane element 1 and being fastened with another part of its adhesive surface to an edge surface of the strip 43 of fire-retardant material facing the window frame 19.

Together, the two strips 43,44 form a fire- retardant barrier between the actual double-glazing pane element 1 and the window sash 6 of aluminium.

Furthermore, the strip 42 forms a fire-retardant barrier between the window sash 6 and the window frame 19 when the window unit 1 is closed. Finally, the actual glazing bead 16 together with the strips 30,33 inserted therein and made of fire-retardant material and together with the section 28 of swellable, fire-retardant material of the glazing strip 25 forms an efficient fire-retardant barrier between the internal glass pane 3 of the double glazing pane element 1 and the window frame 19 of solid wood. If a fire breaks out in the room in which the fire-retardant window is mounted, the exposed wall 39 of the glazing bead 16 is first influenced by the flames, and the empty channel 38 below this wall 39 thus acts as an insulator so that the neighbouring channel 31 is heated more modestly, and the strip 33 located in this channel consequently swells, whereby the channel 31 is expanded like a balloon, the plastic walls of the channel being softened by the heating. As a result of the insulating effect of the channel 38, the neighbouring channel 31 can be expanded without its walls being disintegrated by the high temperature. The strip 30 in the channel 29 formed by the U-shaped section 17 also swells and expands the channel 29. During the swelling of all strips 30,33,25,42,43,44 of fire-retardant material, the cavities in the glazing bead 16 are filled out, and the softened plastic material of the glazing bead 16 and the fire-retardant material together form a strongly swollen string wedged between the double glazing pane element 1 and the window frame 19, thus forming an efficient fire- retardant barrier.

It is evident that the glazing bead 16 can be formed in many other ways than the one shown in the embodiment; it may particularly enclose fewer or more cavities than those shown, and in a particularly simple embodiment it may, for example, be formed as a simple tube in which the swellable, fire-retardant material is located at the outer surface of and/or inside it, or it may be shaped as a U-profile in which the fire-retardant material is located inside or around the U-shaped opening. The starting shape of the glazing bead can be obtained by known, suitable, non-cutting processes, such as injection moulding or extrusion, and the final shape can then be obtained by, for example, cutting out a profile in suitable lengths. The glazing bead 16 may be made of, for example, polypropylene or polyvinyl chloride as well as other suitable synthetic materials other than plastics, and the material may possibly be admixed with fibres, such as, for example, carbon or wood fibres. In general, an appropriate composite material comprising a synthetic material is suitable for manufacturing of the glazing bead. The glazing bead 16 will thus be able to expand in its transverse direction upon heating of the synthetic material.

The window shown may either be openable, the sash 6 then being hung so as to be movable in a direction away from the window frame 19, or with a fixed sash, the sash 6 then being fastened in relation to the frame 19 in the position shown.