GB2034383A - Window insulation - Google Patents

Abstract

A thermal insulation arrangement for a door or a window comprises a transparent sheet drawn down from a spring-loaded roller at the top of the frame. The sheet is creased or embossed in a pattern to define adjacent areas so as to isolate puckering or rippling effects. <IMAGE>

Description

SPECIFICATION Window insulation The invention relates to a thermal insulation arrangement for a window and is particularly suitable for an arrangement of the kind described in Patent Applications Nos.

53913/76 and 45300/77. Briefly, such an arrangement comprises a spring loaded roller mounted across the top of the window-frame, and a flexible sheet wound on the roller so as to fill the frame when drawn down from the roller. Sealing means are provided to restrict or prevent the passage of air around at least the sides of the sheet. Generally, the sheet is of transparent plastics material.

In practice it is found that sometimes the plastics sheet can become distorted slightly by thermal expansion, for example, or perhaps by pressure fluctuations. Although such distortions can be very slight, they are sometimes easily visible because of reflection from the sheet. An object of the present invention is to provide an arrangement in which these effects are reduced or obviated.

According to the invention the sheet is creased in lines in such a way as to sub-divide the area of the sheet to adjacent sections so that distortions of the sheet are not readily transmitted from section to section and are thus localized. The creases may be made by folding and unfolding or may be constituted by embossed grooves.

In one simple embodiment of the invention the sheet is creased with two paralled horizontal lines running near the stiffening bar. The stiffening bar is generally made of aluminium and differential thermal expansion of the plastics material with respect to the aluminium has been found to result in visible distortion at the draw-bar since the draw bar clamps the sheet tightly. Attempts to avoid this effect by providing cushioned clamping have not met with success. Also, the provision of a single crease near the draw-bar, while reducing the effect to some extent, does not entirely solve the problem. It is found, however, that a pair of parallel creases provides a section between the creases which effectively isolate the rest of the sheet from the effects of puckering at the draw-bar. Typically, the parallel creases run one to two inches apart.

Another embodiment of the present invention provides a set of parallel creases over the surface of the sheet, either horizontal, vertical, diagonal or perhaps curved.

Another, and preferred, embodiment of the present invention provides the sheet with a grid of crossed creases which define enclosed sections. The creases may be curved but are preferably straight. The grid may be simply two sets of parallel straight creases, the sets crossing at right angles, thereby defining square or oblong sections. It is found with this arrangement that the adjacent sections are more or less independent as far as the effects of distortions are concerned. Local distortions are restricted by the creases and are not transmitted across the sheet. Thus, the visual effects of puckering at the draw-bar and billowing due to pressure fluctuations are to a large extent reduced. The creases themselves are light enough as to be virtually invisible.

As used herein "crease" generally means a shallow 'V'-shaped indented groove. However, the desired effect can be obtained by shallow 'U'-shaped or square-sectioned indented grooves which can be achieved by embossing.

The grooves may be made by running wheels of suitable cross-section across the sheet. Local heat may be applied to assist the formation of the grooves.

Successive creases of a set of parallel creases may be made in opposite direction in "concertina" fashion.

Preferably the parallel creases, whether in a single set of a pair of crossed sets, are spaced apart less than 25cm, and preferably more than 2cm.

The invention will further be described with reference to the accompanying drawings, of which: Figure 1 is an elevation of a thermal insulation arrangement embodying the present invention; Figure 2 is a scrap cross-section as 'A-A' of Fig. 1; Figure 3 is an elevation of part of a sheet for use in the invention embodying another pattern of creases; and Figure 4 is a diagram showing another arrangement of creases in a sheet for use in accordance with the invention.

Referring to Fig. 1 there is shown a window frame 1 in which is fitted a window 2. Channel-section side members 3, 4 of extruded aluminium are screwed to respective sides of the frame 1 to extend from top to bottom. A base member 5, also of channel section and made from extruded aluminium, is screwed along the bottom of the frame.

At the top of the frame is mounted a springloaded roller 6 on which is wound a sheet 16 of transparent plastics material. The free end of the sheet 16 is clamped in an aluminium stiffening bar 7. Bar 7 has a grip 15 extending along the major part of the bar on the inside. This allows the bar to be drawn down by hand. The grip terminates short of each end of the bar.

The sheet is sealed at the sides and the draw-bar is sealed at the bottom by brush seals (not shown).

The sheet is made of polyester terephthalate, conveniently of the kind marketed under the name "Melinex" (Registered Trade Mark).

Typically, the sheet is of a thickness of 0.004" or 0.005".

As shown in Fig. 1 the sheet is formed with a first set of horizontal creases 8 and a second set of vertical creases 9. The creases of each set are spaced apart in this example by 5cm, thus defining squares of side 5cm. As shown in Fig. 2 the creases are very shallow 'V'shaped creases made in alternate directions in concertina" fashion. The scale of the creases in Fig. 2 is greatly exaggerated for the purpose of illustration.

Fig. 3 shows an alternative pattern of creases, in this case diagonal creases 10, 11 which define diamond-shaped regions.

In Figs. 1 to 3 there are shown arrangements with two crossed sets of creases. It is to be understood that the invention can be put into effect by omitting one set of parallel creases. Thus, in Figs. 1 and 2 set 8 or 9 may be omitted. in Fig. 3 set 10 or set 11 may be omitted.

Fig. 4 shows an arrangement in accordance with the invention in which a horizontal region 12 of the sheet is defined by two parallel creases 13, 14. Crease 13 is about 2cm from the draw-bar and crease 14 is about 2cm from crease 13. This configuration helps prevent the effects of puckering of the sheet at the draw-bar, and may be provided in accordance with the invention above or in combination with a grid of creases as shown in Fig. 1 or Fig. 2.

Claims (7)

1. A thermal insulation arrangement for a window or door in a frame, the arrangement comprising a spring-loaded roller mounted across the top of the frame, a flexible sheet wound on the roller of such a shape and size as to fill the frame when drawn down from the roller, and sealing means to restrict or prevent the passage of air around at least the sides of the sheet, wherein the sheet is creased in lines in such a way as to sub-divide the area of the sheet to adjacent sections so that distortions of the sheet are not readily transmitted from section to section and are thus localized.

2. A thermal insulation arrangement as claimed in Claim 1 wherein the sheet is creased from side to side at one or more places.

3. A thermal insulation arrangement as claimed in Claim 2 wherein the bottom of the sheet is provided with a stiffening bar and the sheet is creased with two parallel horizontal lines running near the stiffening bar.

4. A thermal insulation arrangement as claimed in Claim 1 wherein there is provided a set of parallel creases over the surface of the sheet.

5. A thermal insulation arrangement as claimed in Claim 4 wherein there is provided a second set of parallel creases which cross the creases of the first set, thereby defining a number of adjacent sections.

6. A thermal insulation arrangement as claimed in Claim 4 or Claim 5 wherein the creases of each set are made in alternate directions, concertinafashion.

7. A thermal insulation arrangement substantially as hereinbefore described with reference to the accompanying drawings.