WO2009080026A1

WO2009080026A1 - A weather shield and use of it for a skylight window

Info

Publication number: WO2009080026A1
Application number: PCT/DK2007/050203
Authority: WO
Inventors: Erik Kjaergaard
Original assignee: Vkr Holding A/S
Priority date: 2007-12-20
Filing date: 2007-12-20
Publication date: 2009-07-02
Also published as: EP2231956B1; CN101874140A; EP2231956A1; PL2231956T3; CN101874140B

Abstract

A weather shield for a skylight window comprising a dome portion sur- rounded by and extending into a skirt member, inner edges of said skirt member forming a skirt plane, said dome portion having an apex, a cross-sectional plane normal to said skirt plane extending through said apex, the apex projected onto said skirt plane defining a point A posi- tioned a distance AB in said cross-sectional plane from a point B of said inner edges, said apex being positioned in an apex height H from said point A, said dome portion has a height h greater than or equal to 0.6H from a point C at a distance of 0.2AB from said point B towards said point A.

Description

A weather shield and use of it for a skylight window

The present invention relates in a first aspect to a weather shield for a skylight window comprising a dome portion surrounded by and extending into a skirt portion, inner edges of said skirt portion forming a skirt plane, said dome portion having an apex, a cross-sectional plane normal to said skirt plane extending through said apex, the apex projected onto said skirt plane defining a point A positioned a distance AB in said cross-sectional plane from a point B of said inner edges, said apex being posi-tioned at an apex height H from said point A.

Such prior art weather shields or dome lights (cf. international patent class E 04 D13/03) are often shaped like a hemisphere comprising a peak point or apex from which the surface of a dome portion descends to all sides towards a skirt portion and are typically made from acrylic. It is well known to use such dome lights as windows in flat roofs, i.e. roofs having an inclination in relation to vertical of approximately 0°, i.e. less than about 15°, in order to transmit light into the interior of a building or to provide ventilation. The skirt portion of the domes are usually attached directly to a roof structure or a base mounted in the roof.

A number of problems arise when windows are to be positioned in roofs. One problem is that it is difficult to provide a satisfactory heat transmission coefficient. For instance, a standard acrylic dome light positioned alone over a roof opening results in very poor insulation. One prior art solution lessening this problem is to use a multilayer dome construction in order to reduce the heat loss. Another solution would be to use, for example, a window portion such as a standard Velux® top-hung roof window in combination with a weather shield. A sash encloses a plane, multilayer insulating windowpane, thereby providing a very low overall heat transmission coefficient. Applying a prior art dome light as a weather shield would prohibit water and dirt from accumulating on the window surface and would result in a low heat transmission coefficient. However, tests have shown that in such a structure problems connected with condensation on the entire interior surface of a dome portion of such a dome light arise. These problems arise whenever a temperature difference is present between the air, which is trapped in a space between the windowpane and the weather shield, and the surrounding air. An interior surface of the weather shield and an upper pane surface of the window portion define a somewhat large interior space, which is filled with air. Condensed water on an interior weather shield surface inhibits view and light incidence and might drip down onto an upper pane surface of the windowpane to further inhibit view and light inci- dence and eventually result in a need for cleaning of the windowpane.

It is thus the object of the present invention to provide a weather shield for a skylight window, which when installed to cover a window portion with a windowpane improves view and light incidence through such a skylight window. This object is met by a weather shield of the kind mentioned in the opening paragraph, which is further characterized in that said dome portion has a height h greater than or equal to 0.6H from a point C at a distance of 0.2AB from said point B towards said point A.

Tests have shown that a weather shield according to the inven- tion is especially suited to be mounted on a window portion installed in a flat roof. A dome portion of a weather shield according to the invention comprises a relatively flat top surface and relatively steep side surfaces extending from a skirt portion to said top surface. As a result, a weather shield according to the invention installed to cover a standard window in a flat roof will produce minimal condensation on the top weather shield surface, providing for an improved view and incidence of light through the window. This follows from tests through which it has been recognized that an increased relative distance between the interior dome surface and the windowpane (or frame or sash of the window) reduces con- densation. The water will condensate primarily at the relatively steep portion of the interior surface of the weather shield extending from the inner edges of the skirt member towards said top surface. In a condition of use this steep portion is positioned substantially above or adjacent to the frame and the sash of the window, which can be provided with means for draining condensation. Furthermore, the dome portion of the weather shield according to the invention may be manufactured with a relatively small maximum height, which reduces the overall material consumption. The invention is based on the recognition that the shape of a weather shield and especially the relative heights of a dome portion cross section determines where vapour condensates on the interior side of the dome portion, when the weather shield is installed on a skylight window in a flat roof. Experiments show that water of the air of the inte- rior space primarily condenses on sections of the dome portion with a smaller height. Without the wish to be bound by any specific theory, this is believed to be due to more extensive airflows in parts of the interior space with a larger height. More specifically, air is believed to be heated near the windowpane because of convectional heat transfer from the windowpane, the air rising more or less vertically until having been cooled enough by means of convectional heat transfer from the dome portion to descend again, thus creating a number of vertically extending eddies in the interior space beneath the dome portion. This airflow cycle is continued as long as a temperature difference exists between inside and outside. In parts of the interior space beneath the dome sections with a larger height, the corresponding eddies will also be larger. And, as a consequence, the airflow will be faster in these sections, thus providing for a smaller temperature gradient and less condensed water on the lower surface of the dome portion. Similarly, water will tend towards condensing on sections with smaller heights.

With the weather shield according to the present invention the sections of the relatively flat top surface has a relatively large height. In contrast, the sections of the relatively steep side surfaces have a relatively small height. Since the top surface extends almost in the entire visible field of the window, water primarily condensates at dome portion sections, which seen from the inside appear as small sections at the periphery of the window. This allows for an optimum amount of light to radiate through the dome and window portions.

A ratio h/H of less than 0.6 results in a weather shield in which condensation is a lot more likely to happen everywhere above the win- dowpane and in which the side portions are not inclined enough to guide condensation to a side of the weather shield before dripping down onto the windowpane. With the weather shield according to the invention the shape of the dome light is thus optimized to minimize condensation at areas where condensed water is problematic and to control condensation at areas where condensed water tolerable. In other words, condensation is limited to areas where it is most acceptable.

Note that several (i.e. in fact an infinite number of) planes, which are normal to the skirt plane and extend through the apex, exist in any embodiment of the weather shield according to the invention. According to the invention only one single of these planes need fulfil the requirement regarding the ratio h/H.

In a preferred embodiment of the invention a ratio h/H is less than 0.95, preferably less than 0.8, more preferably less than 0.75 or 0.7.

In another embodiment of the invention, which is especially suitable for a standard skylight window portion, said skirt portion comprises four skirt members forming a rectangular skirt portion. In a mechanically simple embodiment of the invention, said dome portion comprises four side surfaces and a curved top surface. In a further development of this embodiment at least one of said side surfaces is plane.

In an embodiment of the invention, which has shown to be es- pecially useful in order to reduce condensation problems, said plane side surface(s) extend(s) to about half the maximum height H of the weather shield.

In an embodiment, which has proven to be especially useful in order to minimize and control condensation at the interior surface of the weather shield, tangents to said dome portion in said cross-sectional plane at all points from said point B to said apex in relation to said skirt plane form angles in a range from 0 to 70°, preferably 0 to 60°. This ensures that the dome portion has a relatively steep inclination at the first section extending from the skirt member towards the top surface of the weather shield so as to minimize condensation at said top surface and to improve the effect of condensation not dripping on the windowpane, but make it flow towards the skirt portion, which can be provided with means for draining off condensed water. In an embodiment, which provides for reduced material consumption and a pleasing appearance of the weather shield, a ratio H/AB is equal to or in the range of 0.1 to 0.45, preferably 0.25 to 0.35 and more preferable 0.3 to 0.35.

In another embodiment said skirt portion is attached to a sash or a frame of a window portion such that said weather shield covers said sash, preferably a windowpane encompassed by said sash is a plane, multiple layer insulating pane. This provides a structure having a very low heat loss compared to conventional weather shields in a flat roof.

In a second aspect the invention relates to use of a weather shield according to the first aspect of the invention for shielding of a sash of a window portion.

The second aspect of the invention provides advantages comparable to the advantages described above in relation to the first aspect of the invention. In the following the invention will be described in further detail by means of examples of embodiments with reference to the drawings, which are drawn to scale and in which

Fig. 1 is a perspective view of a skylight window comprising a weather shield according to a first embodiment of the first aspect of the present invention,

Fig. 2 is a cross-sectional view of the window according to Fig.

1,

Fig. 3 is a side view of the weather shield of Fig. 1, Fig. 4 is a perspective view of the weather shield of Fig. 1, Fig. 5 is a corner side view of the weather shield of Fig. 1,

Fig. 6 is a top view of the weather shield of Fig. 1, Fig. 7 is a perspective view of a weather shield according to a second embodiment of the first aspect of the invention,

Fig. 8 is a top view of the weather shield of Fig. 7, Fig. 9 is a side view of the weather shield of Fig. 7, and Fig. 10 is another side view of the weather shield of Fig. 7. Throughout the drawings similar reference numbers are used for similar or like elements of different embodiments. Figs 1 and 2 show a skylight window comprising a first embodiment of a weather shield 6 according to first aspect of the invention. The window comprises a window portion 1 in the form of a standard Velux® top-hung roof window (GHL type), which is able to pivot about a vertical axis positioned along a bottom side of the window (to the right in Fig. 2). The window portion 1 is installed in a flat roof 2 and comprises a sash 3 positioned in a frame 4, which are both extruded PVC profiles. The sash 3 encloses a windowpane 5 with two layers of glazing sandwiching a layer of gas to provide insulation glazing.

A weather shield in the form of a dome light 6 is in the form of a dome-shaped plate of acrylic attached to the sash 3 to form a weather shield protecting the window portion 1, the dome light 6 resting on circumferentially extending sealing projections or weather strips 7, 8 of the sash 3. The dome light 6 comprises an apex X from which the dome light upper surface descends to all sides. The dome light 6 is transparent and could also be manufactured from, for example, acrylonitrile butadiene styrene or polycarbonate.

Pivoting the sash 3 and dome light 6 about said vertical axis by means of a chain operator 23 provides movement between an open and a closed position of the window. The chain operator 23 may be driven automatically by electrical operating means and may be radio controlled. An interior surface of the dome light 6 and an upper surface of the windowpane 5 define an interior space 9, which is filled with air.

Figs 3 to 6 show the dome light 6 separated from the remaining parts of the window. The dome light 6 comprises a rectangular skirt por- tion 10 and a dome portion 11, which are transparent and integrally formed.

The skirt portion 10 comprises four skirt members 13 having fastener holes 14 adapted for taking up not shown fasteners for fastening the dome portion 11 to the sash 3 of the window portion 1. The skirt members 13 comprise inner, circumferentially extending edges 15, which form a skirt plane P and from which the dome portion 11 extends. From an outer edge 16 of said skirt members 13 a skirt flange 17 extends in a direction opposite to said dome portion 11, providing the skirt portion 10 with a substantially L-shaped cross section as shown in Fig. 2. Hence, in a mounted condition as shown in Figs 1 and 2, the skirt flange 17 serves as a protection of the window frame 4.

The dome portion 11 comprises a slightly curved top surface 18, which is convex with respect to the skirt plane P, and four substantially plane side surfaces 19, which extend between the inner edges 15 of the skirt members 13 and said top surface 18. However, transitions from the skirt members 13 to the side surfaces 19, as well as from the side surface 19 to the top surface 18 and between the side surfaces 19, are provided by portions 20, 21 and 22, which are at least partly curved or rounded off, providing for a structurally strong dome light 6 with a smooth and rounded surface for effective draining off of rainwater. The dome light 6 is integrally formed, which is achieved by pressing it into shape in a form.

The plane portions of the side surfaces 19 and the portions 21 connecting the top surface 18 and the side surfaces 19 extend towards the top surface in an angle of approximately 45° in relation to the skirt plane P to about half a maximum height H of the dome light 6. This angle can vary within approximately 30° to 60° to provide a section where condensed water can be guided towards draining means positioned at the window portion 1.

The apex X of the dome portion 6 is positioned in the height H from the skirt plane P. A cross-sectional plane normal to the skirt plane P extending through the apex X defines a point B where it intersects one of the inner edges 15 of the skirt members 13. The apex X projected onto said skirt plane defines a point A positioned a distance AB in said cross-sectional plane from the point B of said inner edge.

The shape of the dome light 6 is further defined by a height h from a point C at a distance of 0.2AB from said point B towards said point A. A relationship between H and h as defined in the claims results in a dome shape where condensation will occur on the plane side portions with an inclination steep enough to guide condensation towards the skirt members before it drips down onto the windowpane. At the same time it allows for a height H, which ensures that water will be less in- dined to condensate at the dome portion 11 where it would inhibit view and possibly drip down onto the windowpane 5. In the embodiment shown in Figs 3 to 6 the ratio h/H is approximately 0.66 for said cross- sectional plane. The ratio h/H can be measured for other cross-sectional plane normal to the skirt plane P and extending through the apex X. Of these a cross-sectional plane normal to the presently chosen plane would result in a similar ratio h/H. For comparison a cross-sectional plane extending from corner to corner of the dome portion 11 results in a ratio h/H of about 0.42; i.e. not all cross-sectional planes normal to the skirt plane P and extending through the apex X provide a h/H above or equal to 0.6.

In the present embodiment a ratio H/AB is approximately 0.32 providing for a weather shield with a relatively small extent in the vertical direction.

Starting at the point B and following a line of intersection be- tween the dome light 6 and said cross-sectional plane, a section 20 forms a curved transition from the inner edge 15 of the skirt member 13 to a substantially plane side portion 19, which extends towards the top surface 18 at an angle of about 45°, in relation to said skirt plane P. A similar result could be achieved with other angles of the side portion 19 with respect to the skirt plane P. The side portion 19 transitions into a curved, substantially hemispherical portion 21, which forms a transition from the relatively plane side portion 19 to the top surface 18 of the dome light 6. The curvature of the top surface 18 is relatively small compared to the curved portion 21 forming the transition between the side portion 19 and the top surface 18 and ensures a more even distribution of the dome space 9 across the windowpane 5. The curvature of the top surface 18 ensures drain of rainwater falling on the outer surface of the dome portion.

In the present embodiment tangents to the dome portion 11 in said cross-sectional plane at all points from the point B to the apex X in relation to the skirt plane P form angles in a range from 0 to about 60°.

Whereas Figs 3 to 6 illustrate an embodiment with a quadratic skirt portion 10 having four skirt members of equal length, Figs 7 to 10 illustrate an embodiment of a rectangular, but not quadratic weather shield in the form of a dome light 6 in which opposing pairs of side members 13 are of equal lengths. Again taking a cross sectional plane normal to two of the inner edges 15, the ratio h/H is approximately 0.66 and 0.64 in the longitudinal and transverse directions, respectively, and the ratio H/AB is approximately 0.23 and 0.36 in the longitudinal and transverse directions, respectively.

The invention should not be regarded as being limited to the described embodiments. Several modifications and combinations of the different embodiments will be apparent to the person skilled in the art without departing form the scope of the appended claims.

Thus, a weather shield falling within the scope of the first aspect of the present invention can have more than one apex, or the apex can be in the form of a line or a plane.

Weather shields can take many other forms than in the em- bodiments described in the above and still be within the scope of the first aspect of the present invention. For instance, this requirement can be fulfilled with a weather shield comprising a dome portion shaped as a cylinder section with two substantially plane end surfaces normal to the skirt plane. In this case the apex of the dome portion is in the form of a line extending in a longitudinal direction of the cylinder section.

Another example is a weather shield with a not dome-shaped dome portion, i.e. a dome portion comprising only plane surfaces or the like. However, a dome-shaped dome portion is preferred because of superior strength qualities.

Claims

P A T E N T C L A I M S

1. A weather shield for a skylight window comprising a dome por-tion surrounded by and extending into a skirt portion, inner edges of said skirt portion forming a skirt plane, said dome portion having an apex, a cross-sectional plane normal to said skirt plane extending through said apex, the apex projected onto said skirt plane defining a point A positioned a distance AB in said cross-sectional plane from a point B of said inner edges, said apex being positioned at an apex height H from said point A, c h a r a c t e r i z e d in that said dome portion has a height h greater than or equal to 0.6H from a point C at a distance of 0.2AB from said point B towards said point A.

2. A weather shield according to claim 1, wherein a ratio h/H is less than 0.95, preferably less than 0.8, more preferably less than 0.75 or 0.7.

3. A weather shield according to any previous claim, wherein said skirt portion comprises four skirt members forming a rectangular skirt portion.

4. A weather shield according to any previous claim, wherein said dome portion is dome-shaped and comprises four side surfaces and a curved top surface.

5. A weather shield according to claim 4, wherein at least one of said side surfaces is plane.

6. A weather shield according to claim 5, wherein said plane side surface(s) extend(s) to about half the maximum height H of the weather shield.

7. A weather shield according to any previous claim, wherein tangents to said dome portion in said cross-sectional plane at all points from said point B to said apex in relation to said skirt plane form angles in a range from 0 to 70°, preferably 0 to 60°.

8. A weather shield according to any previous claim, wherein a ratio H/AB is equal to or in the range of 0.1 to 0.45, preferably 0.25 to

0.35, more preferably 0.3 to 0.35.

9. A weather shield according to any previous claim, wherein said skirt portion is attached to a sash or a frame of a window portion such that said weather shield covers said sash, preferably a windowpane encompassed by said sash is a plane, multiple layer insulating pane.

10. Use of a weather shield according to any one of claims 1 to 9 for shielding of a sash of a window portion.