CN111373106A

CN111373106A - Roof window with improved spring assembly

Info

Publication number: CN111373106A
Application number: CN201880075491.2A
Authority: CN
Inventors: 耶斯佩尔·赖伯格
Original assignee: VKR Holding AS
Current assignee: VKR Holding AS
Priority date: 2017-11-24
Filing date: 2018-11-26
Publication date: 2020-07-03
Anticipated expiration: 2038-11-26
Also published as: HUE056557T2; DK201770887A1; PL3714116T3; EP3714116B1; CN111373106B; ES2895371T3; DK180218B1; WO2019101279A1; DK201770887A9; EP3714116A1

Abstract

In a roof window for mounting on an inclined roof surface, a lifting device (10) comprises a lifting arm (14) interposed between a main frame (1) and at least one sub-frame (2, 3) of the roof window. The lifting arm (14) has a first end (12) which is rotatably connected with a skid system (30) which is slidably connected with the main frame (1) in a skid guide (16), and a second end (13) which is rotatably connected with the at least one sub-frame (3). The lifting device (10) further comprises a spring assembly (20) configured to be coupled to the skid system (30) and further to the first end (12) of the lifting arm (14) by means of a coupling mechanism such that the spring assembly (20) is capable of being in an uncoupled state and a coupled state with respect to the skid system (30). The spring assembly in turn comprises a main spring system (29) and a buffer spring system (28) interposed between the main spring system (29) and the lifting device (10). According to the invention, the damping spring system (28) comprises an outer spring (281) and an inner spring (282) of approximately the same predetermined length.

Description

Roof window with improved spring assembly

Technical Field

The present invention relates to a roof window, in particular for installation in a sloping roof surface, comprising a main frame, at least one sub-frame, such as a sash and/or an intermediate frame, and a lifting device comprising a lifting arm interposed between the main frame and the at least one sub-frame, the lifting arm having a first end rotatably connected with a sled system slidably connected with the main frame in a sled guide, and a second end rotatably connected with the at least one sub-frame, the lifting device further comprising a spring assembly configured to be coupled to the sled system by means of a coupling mechanism and in turn to the first end of the lifting arm, such that the spring assembly is capable of being in an uncoupled state and a coupled state with respect to the sled system, the spring assembly includes a main spring system and a buffer spring system interposed between the main spring system and a lifting device.

Background

Windows for mounting on inclined roof surfaces include pivoting, top-hinged, hinged at or near the centre, and finally roof windows which are top-hinged but pivotable for cleaning during normal operation. Examples of overhead windows that pivot for cleaning are disclosed, for example, in applicant's WO-A-89/10460, EP 0733146B 1, EP 1873323B 1 and EP 2762665A 2. In order to allow the sash to be rotated approximately 180 deg. to a position where cleaning is convenient, the sash structure is connected with an intermediate frame with frame arms which in the closed position of the window are located between the upper part of the frame and the sash side members and which follow the sash side members during normal use of the window as a top-hung window.

In roof windows operating fully or partly around the hinge axis at the top, it is known to balance the weight of at least a part of the movable part by means of lifting devices which are inserted between a pair of associated side members of the fixed frame and the sash element, respectively, and one end of which is pivotally connected with one of the side members, while the other end of which is hinged to a sliding seat displaceable along the other side member, said seat being urged in one direction by a tension spring, thereby exerting an outwardly directed pressure on the sash element through the rod. The purpose of this arrangement is to facilitate opening of the window, and the dimensions can be chosen such that the spring can balance the top hinged frame in the desired open position.

It is known from the above-mentioned EP 0733146B 1 of the applicant to provide an auxiliary spring or a damping spring to adjust the spring force during the opening and closing movement of the sash relative to the frame. An auxiliary spring is located between the sliding seat and the lifting spring, the prestress of which can be adjusted by means of a manually operated adjusting element as a function of the roof inclination for supplementing the spring force from the lifting spring within a given range of opening angles of the window. Although this arrangement has proven to work well, the ever increasing demand for better insulated windows has resulted in multiple glazings and, therefore, significantly higher sash weights for a given window size.

Disclosure of Invention

It is therefore an object of the present invention to provide a roof window in which the roof window can be conveniently operated also over a large range of roof inclinations for windows having multiple glazing of greater weight.

This is achieved by a roof window of the type mentioned in the introduction, which is further characterized in that the damping spring system comprises an outer spring and an inner spring having substantially the same predetermined length, and that the inner spring is at least partly accommodated inside the outer spring such that the respective axes of the inner spring and the outer spring extend substantially coaxially.

Thereby, a spring assembly may be provided, wherein the spring characteristics of the damping system are improved, since the outer spring and the inner spring together have a spring constant which is larger than the spring constant of a single spring of the same length. Furthermore, the spring assembly has a greater stiffness, which means that roof windows with heavier sash can be easily operated. Conversely, the improved spring characteristics make it possible to maintain the length dimension of the lifting device, instead of providing the buffer spring as a single, longer spring.

The outer spring and the inner spring may have different spring constants from each other. This is particularly advantageous because the inner spring can be easily formed with a reduced coil size and diameter compared to the outer spring.

In a currently preferred embodiment, the outer spring and the inner spring of the damping spring system have mutually opposite helical directions. This has surprisingly proved to make the spring characteristic of the damping spring system particularly satisfactory.

Other features and advantages will be apparent from the following description of the preferred embodiments, along with the accompanying drawings.

Drawings

In the following description, embodiments of the invention will be described with reference to the schematic drawings, in which

Fig. 1 is a perspective view of a roof window seen from the inside and in an open position;

fig. 2 is a perspective view of a detail of the roof window with a lifting device in a first embodiment of the invention and corresponding to the open position of the roof window of fig. 1;

fig. 3 is an isometric view of a detail of the roof window of fig. 2, in the closed position of the window.

FIG. 4 is a partially exploded view of a detail of FIG. 3;

FIG. 5 is an isometric view of the spring assembly shown in FIG. 3;

FIG. 6 is an enlarged, partial isometric view of the spring assembly shown in FIG. 5;

FIG. 7 is a partially exploded isometric view of some of the elements of FIG. 6;

figures 8a to 8e are isometric views of the elements of figure 7;

FIG. 9a is an enlarged partial isometric view of the detail shown in FIG. 3;

FIG. 9b is an exploded partial perspective view of a detail of a lifting device in another embodiment of the present invention;

figures 10 and 11 are partial isometric views of a detail of a lifting device of a roof window in a second embodiment of the invention;

fig. 12a to 12h are schematic partial side views of an embodiment of the roof window of the invention during coupling and uncoupling of the lifting device;

figures 13a to 13b, 14a to 14b and 15a to 15b are perspective views of details of a roof window in a second embodiment;

fig. 16 shows a schematic perspective view of a detail of a roof window in a third embodiment of the invention;

fig. 17 shows a schematic side view of a detail of a roof window in a further embodiment of the invention;

fig. 18a to 18e are views of a detail of the roof window in the third embodiment, corresponding to fig. 8a to 8e, respectively;

fig. 19 a-19 b are views of a detail of the roof window in the third embodiment, corresponding to fig. 13 a-13 b, respectively;

fig. 20a is a view corresponding to fig. 14a of a detail of a roof window in a third embodiment;

fig. 20b is a partial perspective view of a detail of the roof window in the third embodiment; and

fig. 21 to 24 show a partial or full view, an exploded view or a sectional view of a detail of a roof window in a further embodiment of the invention.

Detailed Description

Referring first to fig. 1, the general configuration of a roof window is shown, which during normal operation is top hinged and which pivots for cleaning. Such a window is shown and described in more detail in applicant's above-mentioned european patent No. 0733146B 1, the contents of which are incorporated herein by reference. In fig. 1a lifting device 10 is shown, now also referring to fig. 2-9 a, which forms part of a first embodiment of a roof window according to the invention.

The roof window comprises a main frame in the form of a fixed frame 1 which is configured for mounting in an inclined roof surface. At least one sub-frame is connected to the fixed frame 1, in the embodiment shown a first sub-frame in the form of a sash 2 carrying a pane 4 and a second sub-frame in the form of an intermediate frame 3. The intermediate frame 3 is fastened to the fixed frame at the top mounting fitting 5 and the sash 2 is hinged to the fixed frame 1 via the intermediate frame 3 at the top of the roof window in order to hang the roof window up during normal operation. The sash 2 is also pivotally connected to the intermediate frame 3 so as to enable rotation of the sash 2 to provide access to the outside of the glazing 4, for example for cleaning purposes. For this purpose the intermediate frame 3 is provided with a frame hinge part 6 of a pivoting hinge fitting. Although not shown in detail, it is clear to the skilled person that the sash 2 is provided with a counterpart sash hinge part of the pivot hinge fitting.

Lifting device 10 includes a spring mechanism 20 and a skid system 30, spring mechanism 20 and skid system 30 cooperating to assist in opening the window, i.e., bringing one or more sub-frames into an angled position relative to the main frame. Here, the user operates the operating means of the window in the form of a handle 7 at the bottom member of the sash 2 from the closed position. The biasing of the spring mechanism 20 of the lifting device 10 acts on the lifting arm 14 which is inserted between the fixed frame 1 and the intermediate frame 3. In turn, the lifting arm 14 applies a moment to the intermediate frame 3 and hence to the window sash, relative to an axis passing through the top hinge pin 11. In combination with the force exerted by the user on the handle 7, which is converted into a lifting moment, the moment generated by the weight of the sash 2 and the pane 4 is overcome. Closing the window from the open position requires a reverse movement of the sash 2 and the relevant parts of the lifting device 10. Similar lifting means may be provided at each side of the roof window. Finally, the roof window is provided with ventilation means 8 for allowing air to pass also in the closed position of the window.

In more detail, the lifting arm 14 has a first end 12 rotatably connected with a skid system 30, the skid system 30 in turn slidably connected with the main frame 1 in a skid guide 16, and a second end 13 rotatably connected with at least one sub-frame 3, the lifting device 10 further comprising a spring assembly 20, the spring assembly 20 configured to be coupled to the skid system 30. Since skid system 30 is connected to lift arm 14, spring assembly 20 is in turn configured to be connected to first end 12 of lift arm 14 by way of a coupling mechanism such that spring assembly 20 can be in an uncoupled state and a coupled state relative to skid system 30.

Additional details and advantages of particular coupling mechanisms are the subject of applicant's co-pending patent application filed on the same day as the present application. Here, the coupling mechanism comprises a first coupling member 21 associated with the spring assembly 20 and adapted to cooperate with a second coupling member associated with the skid system 30. In the first, second and third embodiments shown in fig. 10-11, 13 a-15 b and 18 a-20 b, the second coupling member comprises a skid 31 forming part of the skid system 30, and the skid 31 comprises receiving means configured to cooperate with the first coupling member 21 in the coupled state. The operation of the presently preferred embodiment is described in detail in connection with fig. 12a to 12h of the applicant's co-pending international application filed on the same date as the present application and claiming priority to DK PA 201770889, to which particular reference is hereby made.

In all of the embodiments shown, the first coupling member includes a hook element 21 and the second coupling member includes a receiver for the hook element formed in skid system 30. The hook element 21 is configured to have at least an unengaged position and an engaged position, and the coupling mechanism further comprises a coupling plate 25, the coupling plate 25 being arranged to have at least a first position corresponding to the coupled state and a second position corresponding to the uncoupled state, the coupling plate 25 allowing the hook element 21 to be in said unengaged position. The operation of the presently preferred embodiment will be described in further detail in connection with fig. 12a to 12 h.

In the embodiment shown, hook element 21 of the first coupling member has at least one hook portion 214 facing skid system 30. This provides a particularly easy and secure coupling process.

Even if the coupling mechanism can function properly using only a single hook-and-receiver pairing, it is preferred that the hook-like element 21 has a U-shaped configuration comprising a base portion 212 and two flange portions 213, one hook portion 214 being provided at each of the flange portions 213, as shown.

Turning now particularly to the exploded view of fig. 7 and the detailed individual view of fig. 8a to 8e, the pull rod 22 of the spring assembly 20 comprises a stem portion 221 extending substantially along the length of the spring assembly 20 and a head portion 222 facing the hook-like element 21, the pull rod 22 being provided with at least one

inclined portion

223, 224 at the transition between the head portion 222 and the stem portion 221.

In the first embodiment, the hook-like element 21 of the first coupling member is provided with an aperture 211 in the base plate portion 212 to allow passage of the tie rod 22, such that the head portion 222 of the tie rod 22 is held within the U-shape at the front side of the base plate portion 212 and the stem portion 221 is located at the rear side.

The coupling plate 25 of the coupling mechanism has a base portion 252 which, in the assembled position, is located at the rear side of the base plate portion 212 of the hook-like element 21, i.e. opposite the skid system 30, and which is provided with a rectangular aperture 251 to allow the stem portion 221 of the pull rod 22 to pass through, and wherein the coupling plate 25 is slidable in a plane of the base portion 252 substantially perpendicular to the stem portion 221, so that when the coupling plate 25 is in the bottom position, the hook-like portion 21 can be in its engaged position, and when the coupling plate 25 is in the top position, the hook-like portion 21 is held in its unengaged position.

Furthermore, the coupling plate 25 is here provided with a bottom flange 253, which bottom flange 253 is formed on the base portion 252 to abut on the at least one inclined portion 223 via the base plate portion 212 in the unengaged position. In the embodiment shown, this causes the hook elements 21 to remain effectively in their unengaged position.

The link plate 25 is provided with a cut-out 254 at the top of the base portion 252 to form at least one, preferably two upstanding lugs 255. This simplifies the application of the tool and the re-entry into the coupling position. In addition, the cutout 254 allows for the accommodation of a reinforcing or stiffening element for the sash.

In principle, the configuration of the connection between the first coupling member and the spring assembly 20 can be made in any suitable manner as long as this meets the requirements due to the relatively large forces involved. The stabilizing structure as in this embodiment comprises a corner element 23 which is arranged near the head portion 222 of the tie rod 22 and has an aperture 231 to allow the passage of the shank portion 221 of the tie rod 22.

Here, there is further provided an end piece 24 having an aperture 241 to allow the stem portion 221 of the pull rod 22 to pass through, the end piece 24 further having an upstanding wall 242, a projection 243 being formed on the upstanding wall 242 around the aperture 241 of the end piece 24, and wherein two projecting flanges 244 are provided on either side of the upstanding wall 242 to define a track 245.

As shown, the corner element 23 is provided with an upstanding leg 232 and a bottom leg 233, the aperture 231 of the corner element 23 being provided in the upstanding leg 232, and wherein the two projecting flanges 234 are provided substantially parallel to the bottom leg 233 and each define a gap 235 with respect to the upstanding leg 232.

In the assembled state, the end piece 24 is positioned between the bottom leg 233 and the protruding flange 234, wherein the rear side of the upstanding wall 242 of the end piece abuts the front side of the upstanding leg 232 of the corner element 23, and wherein the base portion 252 of the coupling plate 25 is slidably received in the rail 245 of the end piece and the corresponding gap 235 of the corner element 23.

In order to obtain a smooth movement during the coupling process, each flange portion 213 of the U-shaped hook element 21 here comprises a tip 210 at the front end, a rounded transition 215 between the tip 210 and the hook portion 214, a bottom edge portion 218 between the hook portion 214 and the base plate portion 212, an opposite top portion 217 and at least one

inclined edge portion

216, 219 between the top portion 217 and the tip 210.

In a third embodiment, the configuration of the components of the coupling mechanism shown in fig. 18a to 18e substantially corresponds to the configuration in fig. 8a to 8 e. The following differences exist in the illustrated embodiment; these differences may exist alone or in combination: the hook element 21 is provided with two grooves 217a in the top part 217 to provide possible further guidance. The projecting flanges 244 of the end piece 24 are provided with respective rib portions 244a and two curved flange portions 246 on the side facing the spring mechanism 20. The corner element 23 is provided with an enlarged orifice section 231a adjacent the orifice 231 to accommodate the curved flange portion 246. In this way, easy assembly and secure retention in use is achieved. Finally, the coupling plate 25 is provided with a friction increasing portion 256, for example in the form of a fine thread or other surface treatment, to increase the friction, thereby enhancing the retention of the coupling plate 25 in the desired position. Corresponding friction increasing portions may be provided on opposite sides of the base portion 252. The friction increasing portion may also be provided as a separate element, such as a film or the like applied on the base portion 252. The components of the coupling mechanism need to be appropriately dimensioned relative to each other to avoid excessive friction forces but at the same time to allow proper operation.

Further details of skid system 30 are shown in second and third embodiments in fig. 10-11 and 13 a-15 b and 18 a-20 b. Elements having the same or similar functions as those of the elements of the first embodiment are provided with the same reference numerals.

Referring now in particular to fig. 10-11, 13 a-13 b and 15a, skid 31 of skid system 30 comprises a base portion 310, a first wall portion 311 and a second wall portion 312, preferably one receiving recess 314 being provided at each of the transitions between first wall portion 311 and base portion 310 and between second wall portion 312 and base wall portion 310, and wherein a hole 315 is provided in first wall portion 311 and a hole 316 is provided in second wall portion 312 for receiving shaft 40 connected to first end 12 of lifting arm 14. Finally, the skid 31 is provided with a second opening 318 and a cut-out 319 to make room for the rest of the lifting device 10.

In the third embodiment of the roof window shown in fig. 19 a-19 b the skid 31 is made longer than in the first and second embodiments. This provides greater strength to skid 31. Thus, the incision 319 is made longer.

In the presently preferred embodiment shown and described herein, the receiving means of the second coupling member comprises at least one receiving recess 314 in skid 31 of skid system 30. Other shapes for the second coupling member are also possible. One conceivable alternative solution would be to use the shaft 40 as a receiving means. This alternative solution is shown in fig. 17.

Further details of the shaft 40 shown in fig. 15a to 15b, 16 and 20b are given for informative purposes only and are the subject of applicant's co-pending patent applications filed on the same day as the present application.

In order to more precisely control the frictional forces when the skid system 30 is moved in the skid guide 16, in each of the embodiments described and illustrated in particular in fig. 10 to 11, 14a to 14b and 20a to 20b, the skid system 30 comprises a slide 32, the slide 32 being configured to receive the skid 31 and being provided with at least one recess 324, the recess 324 being opposite to the corresponding receiving recess 314 of the skid 31 of the second coupling member. More details of the slide 32 are shown for informational purposes only; and these details are the subject of applicant's co-pending patent application filed on the same day as the present application. It should be noted that the present invention can also be applied to skid systems without a slide or with a slide of a different configuration. In the embodiment shown, the slide 32 is formed of a plastic material, such as POM, which may also be provided with, for example

Or other treatment having the function of acting as a lubricant to reduce friction.

The constriction 313 on the slide 32 is produced for reasons of space availability. By forming the slide to be slimmer on one side, 322a can be made thicker and provide a tolerance on the side where 322 is located — guiding the shaft 40 in this way so that the end 402 does not protrude causing wear on the sides of the guide.

The edge portion 328 is provided as a cut-out to allow room for the rest of the assembly. Flange portion 329 scrapes the guide to push dirt, such as that collected in a skid guide, toward the sides of the guide.

Fig. 5 and 6 show the general components of the spring assembly 20 of the roof window, and in particular further reference is made to fig. 21 to 24.

The common components of the spring assembly are: a pull rod 22 housing a damping spring system 28 and a main spring system 29. The damping spring system 28 serves as an auxiliary system for the main spring system 29. In order to adapt the same spring assembly to different roof inclinations, an adjustment device in the form of a movable adjustment plate 26 is provided, which is placed in one of several recesses 27a of a spring housing 27 accommodating a damping spring system 28.

As shown, the damping spring system 28 includes an outer spring 281 and an inner spring 282 that are approximately the same predetermined length. The predetermined length of the

springs

281, 282 is typically selected according to the dimensions of the other parts of the lifting device. In the mounted state, the inner springs 282 are accommodated within the outer spring 281 such that the axes of the respective springs extend substantially coaxially.

In the embodiment shown, the outer spring 281 and the inner spring 282 of the damping spring system 28 have different spring constants from one another, and the outer spring 281 and the inner spring 282 of the damping spring system 28 have opposite helical directions from one another.

The spring assembly 20 here further comprises at least one

spring plug

283, 284, the spring plugs 283, 284 being configured to be in contact with a respective end of the inner spring 282 of the damper spring system 28 in the mounted state. That is, here, two spring plugs 283 and 284 form respective ends 283 and 284 of the buffer spring system. During the manufacturing stage, the spring plugs 283, 284 are advantageously provided with friction increasing means on the surfaces configured to be in contact with the respective ends of the inner spring 282 of the damper spring system 28. In this way the two springs are held together in a secure manner.

In principle, the coupling mechanism can be designed and operated accordingly in any suitable manner as long as the basic principles outlined initially are fulfilled. From the following description of the operating steps performed during coupling and uncoupling of spring assembly 20 to skid system 30 in the embodiment shown and described above with reference to the sequence of fig. 12a to 12h, it will be understood that hook element 21 of the first coupling member is arranged in the currently preferred embodiment to slidably contact skid system 30 in one direction and engage said second coupling member 31 in the other direction, i.e. hook element 21 of the first coupling member ensures that the components of the lifting device itself are engaged with the first and second coupling members by being driven in the opposite direction. For ease of reading, not all elements in fig. 12a to 12h are labeled with reference numerals, and the detailed description may refer to the above description of the remaining figures.

Turning first to fig. 12a, the roof window is shown in its closed state, i.e. with one or more sub-frames lying substantially parallel to the main frame. Here, the intermediate frame 3 represents a sub-frame, although not shown, the positions of the skid guides 16 and the spring assemblies 20 indicate the corresponding positions of the fixed frame 1, i.e. the fixed frame 1 is here substantially horizontal for clarity, even though the fixed frame 1 would normally be mounted on an inclined roof surface prior to coupling the spring assemblies 20 to the skid system 30. The coupling mechanism has not yet been activated and skid system 30 is thus located at a distance from spring assembly 20. From the enlarged sectional view in fig. 12a it is evident that the coupling plate 25 is in its first position, i.e. in the bottom position, and that this position corresponds to an engagement position of the hook-like element 21 in which coupling can take place.

When the window is opened by rotating the intermediate frame 3 about the top hinge pin 11, the lifting arm 14 is also rotated and the skid system 30 moves in the direction of the spring assembly 20 and the first coupling member associated therewith in the form of the hook-like element 21. As the position shown in fig. 12b is approached, the hook element 21 slides upwards on the skid 31 and can rotate slightly on the pull rod 22, since the base portion 212 of the hook element 21 can move relative to the inclined portion 223 on the rear side of the head portion 222. The crosspiece 25 is still in its first or bottom position. During continued movement of the intermediate frame 3 in the opening direction and the translational movement of the sled system 30 therewith, the hook portion 214 of the hook element 21 will reach a position directly above the receiving recess 314. As the spring assembly 20 is biased and applies a pulling force to the pull rod 21 towards the left in fig. 12b, the hook element 21 will experience a clockwise moment which in turn forces the hook portion 214 into the receiving recess 314 of the skid 31.

Once coupling has occurred, hook element 21 is further retracted to the left due to the bias of the spring assembly, and hook portion 214 is pulled into stable engagement with receiving recess 314 in skid 31, as shown in fig. 12 c.

The window is now ready for normal operation and during subsequent closing of the intermediate frame 3 movement of the lifting arm 14 pulls the skid system 30 towards the top of the window, i.e. to the right as shown in figure 12 d. As is known per se, the closing movement takes place simultaneously during the further biasing of the spring assembly 20.

If it is desired to remove one or more sub-frames, the roof window is prepared for uncoupling by first rotating the intermediate frame 3 into the open position. The link plate 25 is then brought from its first or bottom position to its second or top position by an upward movement indicated by arrow a in fig. 12 f. In the illustrated embodiment, the window is not fully open in the position of fig. 12f, that is, skid system 30 is not in its leftmost position but is a few millimeters from spring assembly 20. In practice, the sash is rotated to its fully open position and then moved back slightly in the closing direction, leaving the link plate 25 free to move upwards. In this position, the coupling plate is held in its uppermost position by means of friction. Because hook portion 214 is grasping recess 314 of sled 31, hook element 21 remains engaged with sled system 30 until the user grasps the sash and lifts it. During this movement, the hook element 21 is allowed to rotate upwards in a counter-clockwise direction. This brings hook elements 21 to their unengaged position where they cannot be engaged. This action is achieved by the bottom flange 253 of the link plate 25 abutting against the rear side of the base portion 212 of the hook-like element 21. Thus, hook element 21 is subjected to a counterclockwise moment that holds hook element 21 in the unengaged position. The sub-frame can now be detached from the main frame, whereby the intermediate frame 3 is lifted off the connection with the fixed frame 1 here together with the sash 2 and the pane 4. The lifting of the coupling plate 25 can in principle take place in any suitable manner. However, in order to ensure that no undue release occurs, provision is preferably made for the use of suitable tools.

The roof window can be returned to a position ready for coupling by simply rotating the intermediate frame in the closing direction. Towards the end of the closing movement, the lifting arm 14 pushes the link plate 25 downwards in the direction of arrow B in fig. 12 h. Once the counter-clockwise moment previously acting on the hook-like element 21 is released, the hook-like element 21 can be rotated in the clockwise direction to reach the position shown in fig. 12 a.

The invention has been described above with reference to a sash and a frame of a roof window, but it will be appreciated that the invention is also applicable to other frame structural members, such as for example a door frame.

List of reference numerals:

1 Main frame (fixed frame)

2 first subframe (Window sash)

3 second subframe (middle frame)

4 window glass

5 Top mount fitting

Frame hinge part of 6 hinge fitting

7 handle

8 ventilating device

10 lifting device

11 hinge pin

12 first end of lifting arm

13 second end of lifting arm

14 lifting arm

15 Top support fitting

16 skid guide

20 spring assembly

21 first coupling member/hook element

210 tip

211 orifice

212 substrate portion

213 Flange portion

214 hook portion

215 rounded transition edge portion

216 inclined edge portion

217 Top portion

217a recess in the top portion

218 bottom edge portion

219 inclined edge part

22 draw bar

221 shank portion

222 head portion

223 first inclined portion

224 second inclined portion

225 adjusting ring

23 corner element

231 orifice

231a enlarged orifice section

232 upright leg

233 bottom leg

234 projecting flange

235 gap

24 end piece

241 aperture

242 upstanding wall

243 projecting part

244 projecting flange

244a rib portion

245 track

246 bent flange portion

25 connecting plate

251 rectangular opening

252 base portion

253 bottom flange

254 cut

255 vertical leg

256 friction increasing part

26 adjusting plate

27 spring housing

27a recess for adjusting the plate

28 buffer spring system

281 external spring

282 inner spring

283 spring plug

284 spring plug

29 main spring system

291 spring

292 spacer tube

30 skid system

31 second coupling member/skid

310 bottom part

311 first wall part

312 second wall part

313 narrowing part

314 receiving recess

315 hole

316 hole

317 first opening

318 second opening

319 incision

32 sliding part

320 bottom part

321 first wall part

321a first collar segment

322 second wall portion

322a second collar section

323 bowl-shaped part

324 concave part

325 cut

326 incision

327 resilient upstanding portion

328 edge portion

329 flange part

40 shaft

401 patterned end

402 another end portion

403 mark

404 positioning mark

50 friction braking device

51 Friction braking element

52 first taper part

53 second cone part

54 spring plug

Claims

1. A roof window, in particular for mounting on an inclined roof surface, comprising:

a main frame (1),

at least one sub-frame (2, 3), such as a sash (2) and/or a middle frame (3), and

a lifting device (10), the lifting device (10) comprising a lifting arm (14) interposed between the main frame (1) and the at least one sub-frame (2, 3), the lifting arm (14) having a first end (12) and a second end (13), the first end (12) being rotatably connected with a skid system (30), the skid system (30) being slidably connected with the main frame (1) in a skid guide (16), the second end (13) being rotatably connected with the at least one sub-frame (3), the lifting device (10) further comprising a spring assembly (20) configured to be coupled to the skid system (30) by means of a coupling mechanism and further to the first end (12) of the lifting arm (14) such that the spring assembly (20) can be in an uncoupled state and a coupled state with respect to the skid system (30),

the spring assembly comprises a main spring system (29) and a buffer spring system (28), the buffer spring system (28) being interposed between the main spring system (29) and the lifting device (10),

it is characterized in that the preparation method is characterized in that,

the damping spring system (28) comprises an outer spring (281) and an inner spring (282) of substantially the same predetermined length, and the inner spring (282) is at least partially housed inside the outer spring (281) such that the respective axes of the inner and outer springs extend substantially coaxially.

2. A roof window according to claim 1, wherein the outer spring (281) and the inner spring (282) of the damping spring system (28) have different spring constants from each other.

3. A roof window according to claim 1 or 2, wherein the outer spring (281) and the inner spring (282) of the damping spring system (28) have mutually opposite helical directions.

4. A roof window according to any of the preceding claims, wherein the spring assembly (20) further comprises a spring housing (27).

5. A roof window according to claim 4, wherein the spring housing (27) further comprises at least one recess (27a) for receiving an adjustment plate (26).

6. The roof window according to any of the preceding claims, wherein the spring assembly (20) further comprises at least one spring plug (283, 284), the at least one spring plug (283, 284) being configured to be in contact with a respective end of the inner spring (282) of the damping spring system (28) in a mounted state.

7. The roof window according to claim 6, wherein the at least one spring plug (283, 284) is provided with friction increasing means at a surface configured to be in contact with a respective end of the inner spring (282) of the damping spring system (28).

8. A roof window according to any of the preceding claims, wherein the coupling mechanism comprises a first coupling member (21), the first coupling member (21) being associated with the spring assembly (20) and being adapted to cooperate with a second coupling member (31), the second coupling member (31) being associated with the sled system (30), the first coupling member comprising a hook element (21), and the second coupling member comprising a receiving means (31) formed in the sled system (30) and being configured to cooperate with the hook element (21) in the coupled state, wherein the hook element (21) is configured to have at least an unengaged position and an engaged position, and wherein the coupling mechanism further comprises a coupling plate (25), the coupling plate (25) being arranged to have at least a first position corresponding to the coupled state and a second position corresponding to the uncoupled state, the coupling plate (25) allows the hook-like element (21) to be in the unengaged position.

9. Roof window according to claim 8, wherein the spring assembly (20) comprises a pull rod (22), the pull rod (22) comprising a rod portion (221) extending substantially along the length of the spring assembly (20) and a head portion (222) facing the hook element (21), the pull rod (22) being provided with at least one inclined portion (223, 224) at the transition between the head portion (222) and the rod portion (221).

10. The roof window according to claim 9, wherein the hook element (21) is provided with an aperture (211) in a base plate portion (212) of the hook element (21) to allow the pull rod (22) to pass through such that the head portion (222) of the pull rod (22) is held within a U-shape at a front side of the base plate portion (212) and the stem portion (221) is located at a rear side.