GB2316117A - PVC window frames - Google Patents

Abstract

A PVC window frame is described comprising upper outer frame jambs 42, lower outer frame jambs 44 and a transom 40. The lower end of each upper jamb is joined to one end of the transom and the upper end of the corresponding lower jamb is joined to the same end of the transom. Typically, the upper jamb part is narrower than the lower jamb part so that the opposing upper jambs provide a wider recess than the corresponding lower jambs. A sash window effect can be produced with a continuous vertical sight line.

Description

A WINDOW FRAME The present invention relates to a uPVC window frame and, in particular, a casement or open-out window frame which presents the visual appearance of a sash window.

A uPVC window frame is generally formed from two horizontal supports and two vertical jambs which are mitred at their respective ends so that the four parts can be arranged in a square or rectangle. A transom is frequently fitted between the two jambs. Traditionally, the popular uPVC window was a tilt and turn window but, more recently, casement and open out windows have increased in popularity.

Attempts have also been made to imitate classical window designs such as the sash window. Unfortunately, uPVC imitation sash windows have a serious drawback. As uPVC is extruded with a predetermined profile of constant cross-section, the recess defined by the inner profile of the top part of the outer window frame and the transom is ,of necessity, of the same width as that defined by lower part and the underside of the transom. To secure the imitation sash to a uPVC window requires the outer profile of the sash frame to fit into the inner profile of the upper part of the outer frame which causes the inner profile of the sash frame to be disposed inwardly of the lower part of the outer frame. This arrangement breaks the vertical sight line of the inner profile of the window. Wooden versions of the same type of imitation are produced by widening the inner profile of the upper part of the jambs so that an imitation sash can be fitted with an inner profile which aligns with the inner profile of the lower part of the jambs and provides a continuous vertical sight line which more closely mimics the appearance of a genuine sash window. Unfortunately, this solution is not possible with uPVC windows which are extruded and have jambs of constant cross-section which are profiled and internally engineered to provide drainage channels and support. Cutting of the upper part of the jamb would compromise the integrity of the drainage channels and/or the jamb supports and weaken the structure of the frame. An attempt to solve the problem has been attempted which utilises clipon inner profiles placed adjacent the lower part of each jamb to effectively narrow the inner sight line of the lower window frame and produce a continuous vertical sight line with the inner profile of the sash. Unfortunately, this reduces the amount of light entering through the window and the clip-on parts tend to produce an undesired fabricated appearance. As a result the general consensus in the industry is that satisfacr -y imitation sash window frames could not be produced with a continuous vertical sight line.

Thus, according to the present invention there is provided a PVC window frame comprising upper outer frame jambs, lower outer frame jambs and a transom, the lower end of each upper jamb being joined to one end of the transom and the upper end of the corresponding lower jamb being joined to the same end of the transom.

Advantageously, the arrangement of having the vertical jamb in two parts allows the upper part to be narrower than the lower part so that imitation sash windows can be manufactured with a continuous sight line for the inner profile. Thus, preferably, the upper jamb part is narrower than the lower jamb part so that the opposing upper jambs provide a wider recess than the corresponding lower jambs.

As an alternative to the aforementioned invention, where the sash part of the window is located in the lower part, the lower jamb would be narrower than the upper jamb.

Traditionally, the transom is fixed to a continuous vertical jamb by; a) having its ends "V" profiled, b) making a "V" cut at the appropriate place on the inner profile of the vertical jamb and c) placing the end of the transom into the "V" notch provided.

Corresponding cuts are made on the opposite side of the recess to secure the other end other transom. Such a fixing method is not suitable for the present invention where the vertical jamb is separated into two parts at the point where the transom is to be fitted. Accordingly, a number of alternative fixing arrangements are proposed.

In one embodiment, a "V" notch arrangement is used to join the upper end of the lower jamb to the under side of the end of the transom.

In such an arrangement, the upper jamb can be joined to the end of the transom by mitring the respective corners of the joining parts or by having a similar "V" notch arrangement to join the lower end of the upper jamb to the upper side of the end of the transom or the end of the upper jamb can simply be placed on top of the end of the upper side of the transom and thereafter butt welded. Suitable arrangements wherein the means of joining the lower jamb to the transom are used instead for the upper jamb or the means of joining the upper jamb to the transom are used instead for the lower jamb can also be envisaged.

It will be readily appreciated that the invention is not limited to the aforementioned methods of joining the transom to the two part vertical jamb and that suitable cutting processes and welding techniques can be used to join the transom to the two parts of the jamb without compromising the integrity of the extruded PVC parts and which also minimise or totally remove drainage channel problems or the problem of exposure of the internal structure of the extruded jambs.

Embodiments of the invention will now described, by way of example, with reference to the accompanying drawings in which: Figure 1 displays a small uPVC window frame in accordance with the present invention; Figure 2 displays a window frame in accordance with the present invention with the sash element removed; Figure 3 shows an exploded view of the upper/lower jamb and transom profiles; Figure 4 displays a window frame in accordance with the prior art arrangements; Figure 5 shows an exploded view of the jamb and transom connection of the prior art arrangements; Figure 6 displays the prior art sash window frame showing the discontinuance vertical sight line; Figure 7a displays one possible embodiment of the connections between the transom end and the upper and lower jambs; Figure 7b displays a cross sectional view of an upper jamb; Figure 7c displays a cross sectional view of a lower jamb; Figure 7d shows a cross sectional view of a transom; Figure 8a displays the transom/jamb connections after assembly; and Figures 8b, c and d display cross sectional views of the upper jamb, lower jamb and transom respectively.

Referring to figure 1 an imitation uPVC sash window frame has a sash element (4) and a window frame (6). The outer window frame is defined by upper and lower horizontal supports (8, 10), an opposed pair of upper jambs (12a, b) and an opposed pair of lower jambs (14a, b). The window cavity is separated into an upper and lower part by a transom (16) which extends perpendicularly between and is secured to the opposed vertical jambs (12a,b & 14a,b). The lower recess part of the frame and the sash window element part are each further divided by two equally spaced, parallel, vertical window support elements (18a, b and 20a, b) which are aligned with the corresponding support element in the other part. The embodiment described differs from the prior art arrangement shown in figures 4, 5 and 6 in that the upper jamb (12a, b: S a separate component and narrower than the lower jamb (14a, b). The jambs (30b) shown in figure 4 are continuous uPVC frame elements which are typical of those used in the industry. The effect of using such elements is that the sash element (32), which is necessarily a close fit with the cavity (34) formed in the upper part of the window frame, forms a narrower recess with its inner profile (36) than that provided by the inner profile (38) of the lower part of the window frame causing a discontinuous vertical sight line from the top to the bottom of the window frame.

Referring to figure 7a, a transom (40) has a series of three cuts made at its end to correspond with cuts made on the upper jamb (42) and the lower jamb (44). The upper jamb (42) has a mitred end (46) which is designed to be joined to a transom mitred edge (48), extending from the upper edge to the mid-portion of the end of the transom and corresponding to the first of three cuts at the end of the transom (40), and which is also designed to be joined to a 45 degree angled edge (50) extending from the middle to the outer edge of the end of the lower jamb (44). The transom mitred edge (48) and the lower jamb mitred edge (50) form an aligned edge once connected for a flush connection with the opposed upper jamb mitred edge (46).

The lower jamb (44) also has two further cut edges at its end which form a shallow 'V' head for close fitting engagement with the two remaining cut edges on the end of the transom (40) forming a corresponding shallow 'V' notch so that when the 'V' head and notch co-engage the mitred edge of each part aligns with the other to present a plain surface to the mitred edge of the upper jamb so that all three parts can be welded together.

As can be seen from figure 8a, the cuts made in the ends of the transom and upper and lower jambs are such as to maintain the integrity of the profiles (50, 52) in the upper and lower parts of the window frame and also to form a sealed and durable connection between the transom and the upper and lower jambs.

Such an arrangement has not hitherto been used to connect transoms to jambs in uPVC window frames and solves the problem of producing an imitation sash window with a continuous vertical sight line. It will be appreciated that the ends of the transom and the upper and lower jambs can be joined by any suitable welding technique such as offset welding. Preferably, the transom is integrated in such a manner that all drainage channels, grooves for the input of gasketry and beading are aligned. However, it is possible, in some instances, to have slightly misaligned or exposed drainage channels and gasketry so long as the strength requirements of the window frame are met. It will thus be appreciated that there are a number of different ways in which the three components can be joined which will meet the above requirements.

Claims (14)

1. A PVC window frame comprising upper outer frame jambs, lower outer frame jambs and a transom, the lower end of each upper jamb being joined to one end of the transom and the upper end of the corresponding lower jamb being joined to the same end of the transom.

2. A PVC window frame as claimed in claim 1, wherein the upper jamb part is narrower than the lower jamb part so that the opposing upper jambs provide a wider recess than the corresponding lower jambs.

3. A PVC window frame as claimed in claim 1, wherein a sash element of the window is to be located in the lower part and the lower jamb is narrower than the upper jamb.

4. A PVC window frame as claimed in any of claims 1 - 3, wherein a "V" notch arrangement is used to join the upper end of the lower jamb to the under side of the corresponding end of the transom.

5. A PVC window frame as claimed in any of claims 1 - 4, wherein the upper jamb can be joined to the end of the transom by mitring the respective corners of the joining parts.

6. A PVC window frame as claimed in any of claims 1 - 4, wherein a "V" notch arrangement is used to join the lower end of the upper jamb to the upper side of the end of the transom.

7. A PVC window frame as claimed in any of claims 1 -4, wherein the end of the upper jamb is simply placed on top of the end of the upper side of the transom and thereafter butt welded.

8. A PVC window frame as claimed in any of claims 1 - 3, wherein the means of joining the upper jamb to the transom as defined in any of claims 5 to 7 is used instead for the lower jamb.

9. A PVC window frame as claimed in any of claims 1 - 3, wherein the means of joining the lower or upper jamb to the transom as defined by any of the features of claims 4 to 8 are interchangeable.

10. A PVC window frame as claimed in any of claims 1 - 3, wherein suitable cutting processes and welding techniques are used to join the transom to the two parts of the jamb.

11. A method of manufacturing a PVC window frame comprising the steps of: a) cutting two upper outer frame jambs, two lower outer frame jambs and a transom; b) joining the upper jambs to the transom ends; and c) joining the lower ends to the transom ends.

12. A method of manufacturing a PVC window frame as claimed in claim 11, wherein the ends are joined by offset welding.

13. A method of manufacturing a PVC window frame as claim 11 or 12 which incorporates any of the features of claims 2 - 10 into the window frame.

14. A PVC window frame as hereinbefore described and with reference to figures 1 to 3, 7 and 8.