Prior Art By WO 97/04206 (with priority from SE 9502624-1), a win- dow construction having an inwardly opening window leaf is pre- viously known, which in addition to an external, robust safety glass pane includes an internal glass pane unit in the form of a so-called insulation glass, which in turn is composed of two spaced-apart glass panes, which are framed in the casement of the window leaf. More precisely, the insulation glass unit is kept in position in a space between bead-formed portions of the casement pieces and separately inserted mouldings. A drawback of this known window construction is, however, that the case- ment of the window leaf is comparatively robustly dimensioned, whereby the efficient transparent surface through the window leaf is unnecessarily reduced. More precisely, the individual casement pieces have a large thickness (counted as the distance between the glass side and frame side of the casement piece) in relation to the depth (counted as the distance between the in- side and the outside of the casement piece). One reason for this robust dimensioning of the casement pieces is that the same have to be able to carry not only the external safety glass pane, but also the insulation glass pane framed by the casement.

Also in other known, commercially available window con- structions, the window leaves have an unnecessarily limited

transparent surface, often as a consequence of grooves for housing metallic fitting details having to be located in the area outside the edges of the isolation unit.

Objects and Features of the Invention The present invention aims at obviating the above- mentioned drawback of previously known window constructions and at providing an improved window construction. Therefore, a pri- mary object of the invention is to provide a window construc- tion having a window leaf of the multi glazing type, the trans- parent surface of which is optimal in relation to given dimen- sions of the frame and the wall opening at the same time as the casement should be able to carry existing glass panes in a re- liable way. An additional object is to create a window con- struction in which a turnable, inwardly opening window leaf may be combined with a fixed window leaf in an architecturally attractive way. It is also an object to enable manufacture of a window construction consisting of wood throughout, having a long service life and minimal requirements for maintenance.

According to the invention, at least the primary object is attained by means of the features that are defined in the characterizing clause of claim 1. Preferred embodiments of the window construction according to the invention are furthermore defined in the dependent claims.

Brief Description of the Appended Drawings In the drawings: Fig 1 is an exploded figure comprising three cross-sections, situated in a common vertical plane, through a window construction according to the invention, Fig 2 is an enlargement of the intermediate cross-section in fig 1, showing a casement piece characteristic of the invention, as well as a frame piece co-operating there- with, and Fig 3 an additional enlargement of solely the proper casement piece according to fig 2.

Detailed Description of a Preferred Embodiment of the Invention Together, the three cross-sections in fig 1 illustrate a window construction that includes a frame, in its entirety des- ignated 1, as well as two window leaves, viz. an upper window leaf 2 and a lower window leaf 3. In addition to side pieces, not shown, the frame 1 includes three horizontal frame pieces 4, 5 and 6, the first-mentioned one of which forms a top piece for the upper glass unit 2 and the last-mentioned one a bottom piece for the lower window leaf 3. The frame piece 5 forms an intermediate piece that in practice serves as a bottom piece for the upper window leaf 2 and at the same time as a top piece for the lower window leaf 3. The window leaf 3 is fixedly mounted. in the appurtenant frame, while the upper window leaf 2 is turnable (via hinges not shown), more precisely in the di- rection inwards from the frame.

The invention relates in all essentials solely to the above-mentioned window leaf 2, which is visualised on an enlarged scale in figs 2 and 3, to which reference is now made.

The window leaf 2 is composed of a frame-like casement generally designated 7, as well as a glass pane unit B sur- rounded and carried by said casement. In this case the unit 8 includes an inner glass pane 9 and an outer glass pane 10 (the unit 8 may, per se, include more glass panes than only two). If the casement 7 is rectangular or quadrangular, the same com- prises four casement pieces, only one of which, viz. a lower casement piece 11, is shown in figs 2 and 3 (in fig 1, the up- per casement piece 11'of the casement 7 is also shown, while the side pieces are not shown). The individual casement piece 11 has an inner side 12, an outer side 13, a side or frame side 14 turned towards the frame, as well as a side or glass side, generally designated 15, turned towards the glass panes or the centre of the casement.

In the glass side 15 of the casement piece 7, a recess, generally designated 16, opens for receiving and clamping the glass pane unit 8. In the unit 8, the two glass panes 9,10 are held together along the edges by means of suitable distance and fixing members 17, 18.

As is outlined in all figures by means of the veinings, not only the frame 1 but also the casement 7 is advantageously made of wood.

Characteristic of the window construction according to the invention, more precisely the casement 7 thereof, is that the recess 16 in the individual casement piece is formed adja- cent to the outside 13 of the casement piece. More precisely, the recess is L-shaped by being delimited by an outwardly fac- ing breast surface 19 on a framework-forming portion 20 of the casement piece 11, as well as a bottom surface 21 of a bracket- like portion 22, projecting outwards from the framework portion 20. The thickness of said bracket portion 22 (counted as the distance between the bottom surface 21 and the bottom side of the bracket portion) is smaller than the depth of the recess 16 (counted as the height of the breast surface 19). In order for the casement to carry the glass pane unit 8 in a reliable way, the pane unit is, according to the invention, united with the individual casement pieces by means of a fixing joint 23 lo- cated in the area between the breast surface 19 and the inner side of the glass pane 9. Vital for the choice of material in the joint 23 is that the same has to have a good adhesion against glass as well as wood. In practice, the material may advantageously consist of silicone which is founded or in an- other way applied in connection with a distance moulding 24, which is connected to the glass pane 9 and the framework por- tion 20 in a suitable way before the fixing joint 23 is ap- plied. By the fact that the joint 23 is made very strong, the same is alone able to receive a large part of the load which arises as a consequence of the weight of the glass pane unit 8.

This entails in turn that the bracket portion 22 may be made having a very limited thickness. Thus, in the illustrated em- bodiment example, the bracket portion 22 has a thickness of only about 30 % of the total thickness of the framework portion 20 (counted as the distance between the glass side 15 and frame side 14). In practice, the bracket portion 22 may, when the same consists of wood, have a thickness within the range of 15- 45 %, suitably 20-30 %, of the thickness of the framework por- tion.

Adjacent to the edges of the glass pane unit 8, a metal- lic or plastic profile or section 25 is arranged. Said section 25, which co-operates with the bottom piece 11 of the casement, has an inclined drip edge 26. An angular corner portion in the section 25 defines a narrow space in which an additional joint or a joint run 27, e. g. of silicone, is applied. Said joint 27 contributes to clamp the glass pane unit, more precisely by counteracting lateral displacement tendencies in the edge por- tion of the glass pane unit. Particularly, the joint 27 clamps the section 25, which in turn clamps the edge portion of the glass pane unit. In this connection, it should be pointed out that the bracket portions 22 of the casement, together with the appurtenant sections 25, primarily have the purpose of protect- ing the edge portions of the glass pane unit 8, the purpose of carrying and clamping the glass pane unit in the casement being effected by the above-mentioned joint 23.

If the casement is made of wood, the component that forms the bracket portion 22 should have the heartwood thereof turned outwards, as is outlined by means of the annual rings in the drawing figures.

The reference numeral 28 designates a groove that is formed in the frame side 14 of the individual casement piece and which has the purpose of housing different types of fitting details (usually of metal) which are not shown in the drawings.

According to a preferred embodiment of the invention, said groove 28 is laterally displaced in relation to the recess 16.

More precisely, the groove 28 is located inside the bracket portion 22 (i. e. inside a conceived vertical plane in the ex- tension of the breast surface 19). This means that the groove may be formed in the framework portion 20 without requiring space in the area outside the edge portions of the glass pane unit; something that in turn to a large extent contributes to minimize the total thickness of the individual casement piece (= the distance between the frame and glass sides 14,15, re- spectively, of the casement piece).

Inside the groove 28, the framework portion 20 of the casement piece has an extended or projecting edge portion 29, having a seal 30, intended to abut against the inside of a shoulder portion of each co-operating frame piece.

In this connection, it should be mentioned that two additional sealing members act between the casement and the surrounding frame, viz. a pipe-like seal 31 against which the outside of the bracket portion 22 may be pressed, as well as a flexible border 32 which is mounted in the frame and may be pressed elastically deformably against the frame side of the casement pieces.

A primary advantage of the invention is that the bracket portion in the casement that surrounds the glass pane unit may be formed comparatively thin in relation to the rest of the casement by the fact that the strong joint 23 between the inner glass pane 9 and the framework portion 20 can receive the main part of occurring loads. This means that the thickness of the casement may be reduced to a minimum (in practice, the thick- ness of the casement pieces may be reduced with 20 to 30 mm in relation to the thickness of the corresponding casement pieces in conventional window constructions); something which in turn means that the visibility through the casement is optimised and that the insolation, and thereby the energy supply through the glass of the window leaf, may be increased with 5 to 10 %. The relative thinness of the casement is seen with the naked eye in the drawings. Thus, the thickness, i. e. the distance between the frame side 14 and the glass side 15, is only about 55 % of the extension or the distance between the inside 12 and the outside 13.

Another advantage is that the openable outer glass plane of the casement 2 is in harmony with the glass plane of one or more fixed window leaves in one and the same frame or wall opening.

Feasible Modifications of the Invention The invention is not limited only to the embodiment described above and shown in the drawings. Thus, the bracket portions in the casement that surrounds the glass pane unit may be made as a separate element of another material than wood, the element being connected with the appurtenant framework por- tions in a suitable way, e. g. via screw joints. Said separate elements may, for instance, consist of metal or of a composite material, the elements having such a profile that the same may

replace the sections 25 that have been described above. If the bracket portions of the casement consist of wood, the same should have a thickness of at least 12 mm. The thickness of analogue elements in metal or a composite material may be reduced to 4-5 mm (in such cases, the thickness of the bracket portions may be within the range of 5-15 % of the thickness of the framework portions).