The present invention relates to a mounting bracket for installation of a window in a roof structure, said window comprising a frame including a top frame member, a bottom frame member and two side frame members, the mounting bracket comprising a first bracket leg for fastening to the roof structure, and, for fastening to a frame member, a second bracket leg extending from the first bracket leg at an angle, the angle being essentially orthogonal in an unloaded condition of the mounting bracket. The invention furthermore relates to a window for installation in a roof structure provided with a plurality of such mounting brackets.

The term "unloaded condition" in this context means that the mounting bracket experiences only the inherent loads coming from holding the window in place in the roof structure. No externally induced loads, such as loads coming from wind or snow acts on the bracket in the unloaded condition.

A mounting bracket of the above-described kind is for instance known from WO 2010/009727 A1 . The mounting bracket has been made amply stiff so as to be able to hold the window in place even under severe circumstances, such as tough weather.

One downside is, however, that when the window is subjected to for instance an impact, the mounting brackets hold, but other parts of the window break.

Improving the properties as regards impacts or other sudden changes of the load conditions, has been addressed in the prior art, including the ones described and shown in published applications Nos EP1361331A2, US 2008/086960 A1 and KR20120089053A.

Although the above-mentioned suggested solutions provide for some absorption of forces during certain load conditions, there is still room for improvement.

With this background, it is an object of the present invention to provide a mounting bracket of the kind mentioned in the introduction and which provides for improved impact-resistant properties.

This and further objects are achieved by a mounting bracket of the kind mentioned in the introduction, which is furthermore characterized in that in a first load condition, in which forces act on the mounting bracket so as to diminish the angle, a first torque threshold is provided, beyond which plastic deformation of the mounting bracket occurs, and that in a second load condition, in which forces act on the mounting bracket so as to increase the angle, a second torque threshold is provided, beyond which plastic deformation of the mounting bracket occurs, the second torque threshold being different from the first torque threshold.

The first load situation, in which forces act on the mounting bracket so as to diminish the angle, corresponds for instance to a situation of a wind load acting on the window, the wind pulling in the window in a direction out of the roof structure. The second load situation, in which forces act on the mounting bracket so as to increase the angle, corresponds for instance to a situation of a snow load acting on the window, the snow pressing on the window in a direction into the roof structure. Due to the provision of different properties in the two directions, the combination of features aimed at is achieved, and it is possible to design the mounting bracket to have sufficient stiffness to be able to resist for instance snow loads without experiencing plastic deformation. However, when subjected to more severe loads, such as an impact, the second torque threshold will be exceeded and the mounting bracket will yield. The plastic deformation that the mounting bracket experiences in this situation will absorb a major part of the energy from the impact. Thereby less strain is put on the remaining window structure.

Thereby is obtained a mounting bracket that holds when subjected to severe weather conditions, but yields when subjected to even larger loads, such as impacts.

The fact that the mounting bracket itself yields provides for a simple solution keeping the number of parts needed for mounting the window low. It also provides for a compact design. The fact that the plastic deformation of the mounting bracket alters the angle between the two bracket legs essentially without any deformation of for instance the holes provided in the mounting bracket for fastening the mounting bracket to the window and roof structure provides for a continuously secure and relatively well-defined fastening of the window to the surrounding roof structure even after an impact load.

Further details and advantages of the present invention will appear from the appended claims and the non-limiting examples of embodiments, which will be described below with reference to the schematic drawings, where

Fig. 1A is a perspective view of a window according to one embodiment of the invention adapted to be mounted in a roof structure,

Fig. 1 B is a fragmentary perspective view, on a larger scale, of the lower right-hand corner of a window as shown in Fig. 1A with a prior art mounting bracket in a first installation position,

Fig. 1 C is a view corresponding to Fig. 1 B, with the prior art mounting bracket in a second installation position,

Fig. 2 is an isometric view of a mounting bracket in a first embodiment according to the invention,

Fig. 3 is a front view of the mounting bracket in the first embodiment, indicating a first deformation zone,

Fig. 4 is a side view of the mounting bracket in the first embodiment,

Fig. 5 is a front view of the mounting bracket in the first embodiment, indicating a second deformation zone;

Fig. 6 is an isometric view corresponding to Fig. 2, with the mounting bracket of the first embodiment in a deformed state,

Fig. 7 is a front view of the mounting bracket of Fig. 6,

Fig. 8 is a side view of the mounting bracket of Fig. 6,

Fig. 9 is an isometric view of a mounting bracket in a second embodiment according to the invention, and

Fig. 10 is an isometric view of a plurality of mounting brackets in the second embodiment, in a supply condition of the window according to the invention.

Fig. 1A shows a window 1 adapted to be installed in a roof structure (not shown). The window 1 comprises a frame including a top frame member 2, a bottom frame member 3 and two side frame members 4, 5. The window 1 is mounted in the roof structure by means of a number of mounting brackets as will be described in the following. The window 1 also comprises a sash 1 a hingedly connected to the window frame. The general structure of the window 1 including parts of the sash 1 a are known per se and will not be described in further detail.

For mounting the window 1 in the roof structure, a plurality of mounting brackets is provided. In Fig. 1 B, a prior art mounting bracket 6' mounted at the lower right-hand corner of the side frame member 4 of the window of Fig. 1A represents said plurality of mounting brackets. The number of mounting brackets necessary for mounting the window may depend on the window size etc, but usually a plurality of four to eight mounting brackets is used. The installation level in the mounted position provided in Fig. 1 B is an alternative to the standard installation level in the mounted position shown in Fig. 1 C. In the mounted position shown in Fig. 1 C, the mounting bracket 6' is mounted on bottom frame member 3 of the window of Fig. 1A, to provide another installation level of the window 1 in relation to the surrounding building structure. Markings on the window frame are associated with respective grooves for use with the plurality of mounting brackets in a desired level. Details regarding the mounting bracket 6' and the installation thereof are described in Applicant's European patent application with the publication No. 2578763A1 .

Fig. 2 shows a mounting bracket 6 according to a first embodiment of the invention in closer detail. Reference is also made to Figs 3 to 5, showing further views of the mounting bracket 6 in the first embodiment.

In Fig. 2, an orthogonal co-ordinate system x-y-z is shown for clarity reasons only. The components of the mounting bracket 6 may be defined by any other system of orientation.

The mounting bracket 6 comprises a first bracket leg 7 for fastening to the roof structure, and a second bracket leg 8 for fastening to a frame member 2, 3, 4 or 5 of the window 1 . The second bracket leg 8 extends from the first bracket leg 7 at an angle a in the embodiment shown. It is also conceivable that the first and second bracket legs 7, 8 are not adjoining but that an intermediate element or section is present. The mounting bracket is in Figs 2 to 5 shown in an unloaded condition, and as is seen, the angle a is essentially 90° in the unloaded condition of the mounting bracket 6. Referring to the coordinate system, the first bracket leg 7 extends essentially in the xy plane and the second bracket leg 8 essentially in the yz plane in the embodiment shown.

In the first embodiment, two flanges 9 extend at an angle β from the second bracket leg 8, so that an edge 10 of the flange 9 faces the first bracket leg 7. In the embodiment shown, a gap 19 is present between the edge 10 and the first bracket leg 7. In the depicted first embodiment, the edge 10 is proximal to the first bracket leg 7 in the unloaded condition such that the gap 19 between the edge 10 and the first bracket leg 7 is approximately 0.2 mm across the whole length of the flange edge 10. The term "proximal" envisages gaps in the order 0.1 to 0.3 mm. Also skewed gaps presenting a varying distance between the flange edge and opposing bracket leg are conceivable. However, it is also conceivable that the edge 10 of the flange 9 is located adjacent to the first bracket leg 7, i.e. no gap present.

In the depicted first embodiment, the angle β between flange 9 and the bracket leg 8, from which the flange 9 extends, is essentially 90°. That is, the angle β is the angle measured in the xy plane in the co-ordinate system. However, other values for the angle β are conceivable, preferably in the range of 45° to 135°, probably more preferred 70-1 10°, most preferred 80°-100°, in order to provide for a sufficiently robust design of the flanges acting as stiffening ribs. For embodiments where the angle β is larger than 90°, the opposing bracket leg should extend further than is the case of the first embodiment of Figs 2 to 5 so as to be able to be abutted by the flange edge in that position of the flange.

The angle γ between the flange 9 and the opposing bracket leg 7 is essentially orthogonal in the embodiment shown. Referring to the co-ordinate system, angle γ is the angle measured in the yz plane. It is noted that both of the angles γ and β are orthogonal in the first embodiment shown in Figs 2 to 8 in order to obtain a robust construction. However, combinations of various sizes of angles for both β and γ are conceivable.

Embodiments comprising just one flange or more than two flanges are also conceivable; however, embodiments with an essentially symmetric arrangement of more than one flange around a symmetry plane C are preferred in order to ensure a uniform deformation, as will be further described below.

The flanges 9 in the first embodiment are integrally formed with the second bracket leg 8. The integrally formed flanges 9 have been obtained by bending and extend from each end 18 of the second bracket leg 8. Embodiments with flanges that are not integrally formed with the mounting bracket leg, from which they extend, or combinations of integrally and not integrally formed flanges, are conceivable. Non-integral flanges could for instance be added, for instance welded or bolted, onto the respective mounting bracket leg. A mounting bracket with three or four flanges may for instance comprise an integrally formed, bent flange at each end of the second bracket leg and one or more flanges added onto the second bracket.

As is seen, the flanges 9 of the first embodiment are substantially triangular with a straight free edge 20. This is beneficial with regard to maximizing the stiffness of the flanges 9 acting as stiffening ribs in the first load condition, while minimizing the overall weight of the mounting bracket. Nevertheless, other shapes of flanges are conceivable, for instance rectangular or flanges with a convexly or concavely curved free edge.

Although described mainly in this context as if the flanges 9 extend from the second bracket leg 8 so that their edges 10 are proximal to the first bracket leg 7, it is understood that the opposite, namely that the flanges 9 extend from the first bracket leg 7 in such a way that the flange edges 10 are proximal to the second bracket leg 8, is also conceivable.

Referring now in particular to Fig. 4, the forces acting on the window 1 in various load conditions will be described. In the installation position shown in Fig. 4, the first bracket leg 7 is fixed to the roof structure and a frame member of the window 1 is fastened to the second bracket leg 8. Forces F1 and F2 acting on the window 1 are transferred to the mounting bracket 6 as will be described in the following:

In a first load condition, forces F1 act on the window 1 and are transferred to the mounting bracket 6 so as to diminish the angle a. The mounting bracket 6 of the first embodiment deforms elastically. The gap 19 is minimized, if not already closed, as the edge 10 of the flange 9 is brought into abutment with the other bracket leg 7 than the one 8 it extends from. As there prior to deformation was a gap 19, essentially contact between the flange edge 10 and the first bracket leg 7 will arise. In case of an initially skewed gap narrowing away from the interconnection 13 between the first bracket leg 7 and the second bracket leg 8, the contact zone will become more point-shaped.

The flanges 9 acting as stiffening ribs in the first load situation provide for a first torque threshold T1 in the first embodiment. As mentioned above, the mounting bracket is so designed as to be able to withstand even severe yet commonly occurring loads in this situation, such as wind loads acting on the window.

In a second load condition, forces F2, as indicated in Fig. 4, act on the window 1 and are transferred to the mounting bracket 6 so as to increase the angle a. The flange edge 10 is being brought out of its proximity to the other bracket leg 7, and thus the flanges 9 lose their effect as stiffening ribs in this load situation. Hence, the mounting bracket 6 is provided with a second torque threshold T2 in this load situation, beyond which plastic deformation of the mounting bracket 6 will occur. The second torque threshold T2 is thus mainly dictated by the remaining design of the mounting bracket, which will be discussed below.

The mounting bracket 6 is so designed as to be able to withstand even severe yet commonly occurring loads in this situation, such as snow loads acting on the window, without exceeding the second torque threshold T2, i.e. only deforming elastically. However, when subjected to larger loads, such as an impact, the second torque threshold T2 will be exceeded and the mounting bracket 6 will deform plastically thereby absorbing energy from the impact protecting other parts of the window and surrounding structure.

The second torque threshold T2 is smaller than the first torque threshold T1 , but embodiments where the opposite is the case might be envisaged.

In the first load condition, when the window 1 is subjected to forces F1 , deformation of the mounting bracket 6 in the first embodiment occurs primarily in a first deformation zone 1 1 in the first bracket leg 7. As indicated in Fig. 3 showing the mounting bracket 6 of the first embodiment, the first deformation zone 1 1 is essentially line-shaped and extends along a line 15. The line 15 is essentially parallel to the longitudinal extension of the interconnection 13 of the first bracket leg 7 with the second bracket leg 8. The line 15 is also offset from the interconnection 13 so as to intersect a point of contact 14 between the first bracket leg 7 and the flange edge 10. The point of contact 14 is essentially the point of contact farthest away from the interconnection 13, since this will be the natural bending point in the first load situation.

Variations in the flange design providing for variations in the shape of the first deformation zone may be envisaged. For instance, a rounded tip of the flange where the free flange edge and the abutment flange edge meet may provide for a broader, more strip-shaped, first deformation zone.

In the second load condition, deformation of the mounting bracket 6 occurs primarily in a second deformation zone 12 in the first bracket leg 7. The second deformation zone 12 is delimited by the interconnection 13 and the line 15 and is marked by a darker colour in Fig. 3. In the second load situation, deformation will occur in whole or parts of the second deformation zone 12 depending on the specific design of the area.

In Fig. 5, the mounting bracket 6 of the first embodiment has a weakening geometry in the second deformation zone 12. In the embodiment shown, the weakening geometry is in the form of a slit 16 but could also take other forms. The slit is, in the embodiment shown, essentially centrally placed in the second deformation zone 12 and extending with its longitudinal extension essentially parallel to the interconnection 13 and with equal distance to the line 15 and the interconnection 13. The particular position and orientation of the slit may vary.

The dimensions of the slit 16 may be varied according to specifications and legislative regulations and furthermore taking into account climate conditions including the risk of extreme weather. In the first embodiment of the mounting bracket 6 shown in Fig. 5, the slit 16 extends across approximately 70-90 percent of the width wd2 of the second deformation zone 12 and across approximately 5-15 percent of the height hd2 of the second deformation zone 12. This arrangement provides for areas in the second deformation zone indicated in Fig. 5, which areas will undergo the most plastic deformation.

Other percentages, arrangements and combinations of weakening geometries are conceivable and may for instance include a number of small holes or perforations, two or more slits arranged in an array, areas of smaller material thickness than the remaining second deformation zone etc. possibly resulting in other deformation areas than the ones indicated.

In the first embodiment, the first bracket leg 7 is essentially T-shaped in that the width of the first bracket leg 7 at the second deformation zone 12 is essentially identical to the width wd2 of the second deformation zone 12, while the width wl1 of the remainder of the first bracket leg 7 is larger than the width wd2 of the second deformation zone. The relationship between the narrower and the wider part of the first bracket leg is around 0.45, but may vary between 0.40-0.50 or even 0.30-0.60 so as to fit well to various sizes and types of windows and roof structures.

The overall height hl1 of the first bracket leg is essentially 1 .5-3 times the height hd2 of the second deformation zone 12, but may also vary so as to fit to various sizes and types of windows and roof structures. The width wl2 of the second bracket leg 8 is essentially equal to the width wd2 of the second deformation zone 12 but may also vary.

As mentioned earlier, the first torque threshold T1 and the second torque threshold are different from each other. In the first embodiment, the first torque threshold T1 is substantially larger than the second torque threshold T2. Typical ratios T1 :T2 are 1.5 to 5, but depending on the window, expected loads and use, however, other ratios are envisaged.

In Figs 6 to 8, the configuration of the mounting bracket 6 of the first embodiment following an impact is shown. As may be seen, the mounting bracket 6 has undergone plastic deformation in the deformation zones described in the above. Hence, the first bracket leg 7 has been twisted and slightly bent, the slit 16 has been stretched, and the gap 19 between the edge 10 and the first leg 7 has widened. Referring now to Figs 9 and 10, a second embodiment of the mounting bracket according to the invention will be described. Elements and parts having the same or analogous function as in the first embodiment of Figs 2 to 8 carry the same reference numerals to which 100 has been added. Only differences relative to the first embodiment will be described.

One difference relevant to the present invention is that the flanges 109 are angled slightly outwards and form another angle (corresponding to angle β described with reference to Fig. 2) than orthogonal with the second bracket leg 108.

Furthermore, the edge 1 10 has an extension providing a point of contact 1 14 between the edge 1 10 and the first bracket leg 107.

The configuration of the mounting bracket 106 in this second embodiment furthermore includes a profiling of the edge of in particular the first bracket leg 107 which enables accommodation of a corresponding mounting bracket installed on an adjacent window.

In a presently preferred embodiment of the window according to the invention, a plurality of mounting brackets 106 of the second embodiment is provided separately from the window, for instance the window 1 of Fig. 1 , in a supply condition.

The mounting brackets 106 of the plurality provided with the window 1 in the supply condition may as shown in Fig. 10 include four mounting brackets 106. In the embodiment shown, these mounting brackets 106 are stacked on each other in a stacking unit 150 which is able to accommodate all four mounting brackets 106, and if necessary several more mounting brackets. The stacking unit 150 includes a set of protruding fingers 151 introduced through the respective slits 1 16 of the mounting brackets 106.

The invention should not be regarded as being limited to the embodiments shown in the drawings and described in the above. Several modifications and combinations may be carried out within the scope of the appended claims. Window

Top frame member

Bottom frame member

Side frame member

Side frame member

Mounting bracket

First bracket leg for fastening to roof structure

Second bracket leg for fastening to frame member

Flange

Edge of flange

First deformation zone (so as to diminish a, wind load)

Second deformation zone (so as to increase a, snow load or impact)

Interconnection between first and second bracket legs

Point of contact between first bracket leg and flange farthest away from interconnection

Line along with which first deformation zone extends, parallel to the interconnection and intersecting point of contact

Slit in second deformation zone

Each end of second deformation zone

Each end of second bracket leg

Gap between flange edge and other bracket leg

Free edge of flange Mounting bracket (second embodiment) First bracket leg for fastening to roof structure

Second bracket leg for fastening to frame member Flange

Edge of flange

Point of contact

Slit (weakening geometry) 150 stacking unit

151 protruding fingers

a Angle between first and second bracket legs

β Angle between the flange and the bracket leg from which the flange extends

Y Angle between the flange and the other bracket leg (from which the flange does not extend)

C Symmetry plane through mounting bracket

F1 Forces acting on the mounting bracket in a first load condition (so as to diminish a)

F2 Forces acting on the mounting bracket in a second load condition

(so as to increase a)

T1 Torque threshold for plastic deformation during first load condition T2 Torque threshold for plastic deformation during second load condition

wl1 Width of first bracket leg (except at second deformation zone) hl1 Height of first bracket leg

wl2 Width of second bracket leg

hl2 Height of second bracket leg

wd2 Width of second deformation zone

hd2 Height of second deformation zone