GB2274676A

GB2274676A - Lockable window hinge

Info

Publication number: GB2274676A
Application number: GB9324980A
Authority: GB
Inventors: John Ouirke
Original assignee: CHELOX Ltd
Current assignee: CHELOX Ltd
Priority date: 1992-12-07
Filing date: 1993-12-06
Publication date: 1994-08-03
Also published as: GB9324980D0

Abstract

A lockable window hinge comprises an elongate track (1) which is attachable to either the inner or outer frame of the window, a closure member 5 which is attachable to either the inner or outer frame of the window, a carriage mechanism (7, 10, 14, 15) for connecting the closure member (5) to the track so that the closure member can swing towards or away from the track (1), the carriage including a first support arm (7) having one end pivotally attached to the track (1), and another end pivotally attached to the closure member (5), and at least one further support arm (10) having a first end pivotally attached to the closure member (5) and a second end slidably attached to the track (1) so as to be slidable along the track (1), and a lock (20) for locking the closure member (5) to the track (1) in one or more pre-determined positions, in which the second end of the further support arm (10) is lockable in one or any one of a plurality of positions along the track (1), by operating the lock (20). <IMAGE>

Description

LOCKABLE WINDOW HINGE The present invention relates to hinges for windows, and particularly although not exclusively, to a hinge which is suitable for a UPVC or aluminium window.

Conventional UPVC windows are known which have an inner frame in which is mounted a pane of glass or the like, and an outer frame which is fixed to a wall of a building. The inner frame is openable with respect to the outer frame and is supported thereon by hinges such that the inner frame can be swung in a direction away from the building and outwardly from the outer frame. The inner frame is accessible by a user from inside the building.

However, conventionally there is a problem with security with this type of window. It is possible for a person standing outside the building to further open the window from outside the building, and thereby gain access to the building.

According to one aspect of the present invention, there is provided a hinge assembly for a window having an inner and an outer frame, the hinge comprising: an elongate track which is attachable to one of said inner or outer frames; a closure member which is attachable to the other one of said inner or outer frames; means for movably connecting the closure member to the track such that the closure member can swing away from or towards the track, the connecting means including a first support arm having one end pivotally attached to the track and another end pivotally attached to the closure member; at least one further support arm having a first end pivotally attached to the closure member, and a second end slidably attached to the track so as to be slidable along the track; and locking means for locking the closure member to the track in one or more predetermined orientations; wherein said second end of the further support arm is lockable in any of one or more positions along the track by operation of the locking means.

Preferably, said connecting means further comprises a slider member which is retained to the track and which is slidable along the track.

Preferably, said second end of the further support arm is attached to the slider member and the slider member is lockable along the track in any of one or more of a plurality of positions, along the track.

Preferably, the locking means comprises a locking pin adapted to move in a direction transverse to a direction of movement of the slider member, and one or more holes defined in the slider member, wherein the locking pin is arranged to engage with a said hole for locking the slider member in a corresponding locked position with respect to the track.

The holes may be cylindrical or of square or rectangular cross section.

The locking pin may comprise an elongate member, having an ovoid aperture therethrough.

Preferably, the locking pin has an upwardly extending engagement part for engaging a said hole in the slider member. The engagement part may be substantially cylindrical or may have a square or rectangular cross section in a plane transverse to the direction of action of the engagement part. Where the cross section is square or rectangular, a greater loading of the pin may be accommodated than where a similar locking pin having a cylindrical engagement part is provided.

Preferably, the locking means is capable of being incorporated substantially inside the inner or outer frame so as to be substantially concealed from view.

Preferably, the locking means and track are adapted for fitment to the inner or outer frame such that, in use, the locking pin is arranged to pass from the respective inner or outer frame and through an aperture in the track to engage in a said hole in the slider member. This may allow the locking means to be incorporated within the inner or outer frame so as to provide a neat locking arrangement which is easily accessible from inside a building and may allow the hinge to be substantially hidden form view when the window is closed.

The locking means may further comprise a housing for carrying the locking pin, the housing comprising a floor part and an upwardly extending wall part.

Preferably, the locking means is key operated. The locking means may further comprise a barrel lock. This may provide a convenient and compact form of lock for fitting inside the inner or outer frame.

Preferably, the key is a removable key. This may allow a window to be locked in a predetermined open or closed position, which cannot be altered or tampered with when the window is left unattended. Changing the opening of the window may require use of the key.

Preferably the key has a double sided key cut portion for maximum security and difficulty of copying.

Preferably, the slider member has means for adjusting a frictional force between the slider member and the track, so as to adjust a stiffness of opening of the inner frame with respect to the outer frame. Such a means may be a simple screw in a tapped hole in the slider member, arranged for tightening the slider member in a channel in the track.

The locking means may be push button operated.

Preferably, the locking pin is biassed into engagement with a said hole, to provide automatic locking of the inner frame to the outer frame. A suitable biassing means may be a compression spring housed in a said housing.

The locking means may be adapted to be concealed within the inner or outer frame of the window, and may thus provide a neat arrangement for locking the window in a selected open or closed position. Preferably, the locking means is incorporated within the outer frame, and the track is attached to the outer frame.

Preferably, the connecting means further comprises a third support arm having one end pivotally connected to the slider member and another end pivotally connected to the first support arm.

Preferably, said connecting means further comprises a fourth support arm having one end pivotally connected to the closure member, and another end pivotally connected to the third support arm.

The invention includes a window fitted with a hinge according to the above first aspect.

The invention includes a method of securing a window fitted with a hinge according to the above mentioned aspect.

The invention includes a method of fitting a locking means according to the above mentioned aspect to an inner or outer frame of a window, the method comprising the steps of; forming a first hole in the inner or outer frame; fitting a said locking pin assembly into said first hole, such that a locking pin is capable of moving between an extended position or a retracted position, movement between the said positions being along an upright axis; forming a second hole in the inner or outer frame; fitting a lock into the second hole, the lock being arranged to engage the locking pin assembly such that a movement of the lock about an axis transverse to the upright axis causes a corresponding movement of the locking pin between the extended and retracted positions.

The movement of the lock about the transverse axis may be a rotational movement between a first rotational position and a second rotational position.

The invention includes a stay assembly for a window or door having an inner frame and an outer frame, said assembly comprising: an elongate track which is attachable to one of said inner or outer frames; a first slider member arranged to slide along said track; a locking means for locking said first slider member to said track in one slider member position or any one of a plurality of slider member positions along said track; and a first stay arm having a first end attached to said slider member and a second end attachable to the other one of said inner or outer frames; wherein said inner frame can be locked to said outer frame in one frame position or any one of a plurality of frame positions corresponding to said one slider member position or any one of a plurality of said slider member positions.

Preferably, the stay assembly further comprises a second slider member attachable to said inner or outer frame; and a second stay arm, wherein said second stay arm has one end connectable to said second slider member and another end connectable to said first stay arm.

Figure 6 shows a view of a locking pin assembly of the second locking means; Figure 7 shows another view of the locking pin assembly of figure 6; Figures 8 to 10 show different views of a locking pin of the second locking means; Figures 11 to 14 show various views of a housing of the second locking means; Figure 15 shows parts of second locking means installed in an outer frame of a window; and Figures 16 to 25 show further embodiments of components which may be used in place of corresponding components of the above assemblies.

Referring to Figure 1 of the accompanying drawings, a part of a hinge assembly comprises an elongate track member 1 having a channel 2 extending along its length and defined by overhanging elongate rails 3 and 4; a closure member 5 for attachment to the other one of the inner or outer frame, the closure member having clearance holes 6 to allow attachment by fixing means such as a screw or rivet; a first support arm 7 having one end 8 pivotally attached to an elongate track member, and another end 9 pivotally connected to the closure member; a further, second, support arm 10 having a first end 11 pivotally connected to the closure member, and a second end 12 pivotally connected to a slider member 13 which is arranged to slide along the channel 2, the slider being retained therein by the overhanging portions 3 and 4; a third support arm 14 having a first end pivotally connected to the first support arm 7 and a second end pivotally connected to the slider member 13; and a fourth support arm 15 having one end connected to the closure member and another end connected to the fourth support arm.

The assembly further comprises a locating means 16 comprising a projection 17 which is for example a plastics moulding attached to the end of the closure member 5, and a correspondingly shaped recess member 18 which slots into the channel 2 of one end of the track 1.

The underside of the slider member 13 is provided with one or more holes 20, which can be in the form of circular or other shaped (e.g. square) recesses, or circular or other shaped (e.g. square) apertures which extend all the way through the slider member. For clarity, only one such hole is shown in Figure 1, although a plurality of holes may be provided. The slider member also is provided with an adjustment screw 21 at one end of the slider member, which urges a plate member (not shown in Figure 1) provided on the underside of the slider member against the base of the channel 2, thus urging the slider member between the overhanging portions 3 and 4 and the base of the channel 2, which screw member is adjustable to vary the amount of friction of the slider member 13 as it slides along the channel.

The track is provided with an aperture for passage of a locking means (not shown in Figure 1) therethrough to engage the hole 20.

In use, the components shown in figure 1 are arranged such that the track is preferably attached to an outer window frame, and the closure member is preferably attached to the inner window frame, such that the inner frame can open outwardly with respect of the outer frame.

When the inner frame is closed with respect to the outer frame, the components are completely concealed within a space between the inner and outer frames and hidden from view.

In the closed position of the window, and/or any one of a number of open positions, the slider member can be locked in the channel by engagement of a locking pin through the aperture in the channel to engage a hole in the slider member.

Referring to Figure 2 of the accompanying drawings, an exploded view of the first specific embodiment is shown.

In addition to the components described with reference to Figure 1 above, the hinge assembly further comprises a lock 31, of a rotating barrel type having an extending pin 35 which acts upon a base plate of a locking pin 33 which moves in a direction transverse to the direction of movement of the slider member 13 in the track 1, (i.e. the locking pin moves up and down as shown in Figure 2). The assembly also comprises a key 34 for operating the lock 31, and resilient means e.g. a spring 32 for urging the locking pin 33 upwards to engage the slider member 13 in a default condition.

The lock 31, spring 32 and locking pin 33, are adapted to be incorporated within a lower member of an outer window frame, and may be attached by, for example, spring clips, metal brackets or guides etc. within the outer frame.

The track 1 has an aperture 30 through which the locking pin is urged to cooperate with a hole 20 (now shown in Figure 2) on the underside of the slider member 13.

Referring to Figure 3 of the accompanying drawings, the slider member 13 comprises an elongate body having first and second holes 40, 41 respectively for attachment of the second and third support arms respectively, which holes may be countersunk as shown in the reverse side 42 of the member. There are also a plurality of holes 20, which may be recessed in the underside 42 of the slider member, or may be through-apertures. The holes are of a size suitable for accommodating the locking pin 33.

The slider member further has an adjustment means comprising a screw 43 and tapped plate 44 (shown separately in perspective view), which locates in a recess 45 on the underside of the slider member.

In use, the adjustment neans urges the slider member away from the floor of the channel 2 such that upper portions 46, 47 respectively of the slider member urge against overhanging portions 3, 4 respectively of the track. Thus, the friction between the upper portions 46 and 47 and the overhanging portions of the track 3 and 4 respectively, can be increased, making it harder to slide the slider member in the track, and therefore making opening of the closure member with respect to the track of much stiffer.

The holes 20 are preferably recessed rather than through apertures, as this may provide an advantage that in use, the locking pin cannot be pushed back through the holes from above, using a sharp implement.

The holes 20 may be of square or rectangular cross section. In use, when the window is attempted to be forced open, the slider member acts perpendicular to the direction of up or down movement of the locking pin, and a square cross section of the locking pin head may provide a greater resistance to downward slippage of the locking pin against the resilient bias (eg spring) than is possible with a circular cross section pin head of diameter comparable to a length of one of the sides of such a square headed pin.

A square or rectangular headed pin may also generally provide a better location in the recess or aperture of the slider member, and a stronger resistance to a forcing of the slider member along the track when the hinge is forced.

However, where a cylindrical locking pin head is provided, a circular hole in the track may be used, which may lead to easier manufacture.

Preferably a square headed locking pin is provided.

Referring to Figure 4 of the accompanying drawings, there is shown the first hinge assembly installed in a window frame having inner and outer frames 60, 61 respectively.

In use, the lock 100 is operated from inside the building. The key may be removed, making entry via the window by persons outside the building less likely, since the key is required for operation of the lock.

The locking pin is biassed such that it is urged against the underside of the slider member 13. If the slider member is positioned inadvertently such that the holes 20 do not correspond with the locking pin 33, and if the slider member is then moved, for example by a person wishing to open or close the window, then the locking pin engages the next available hole, by virtue of the bias of the pin to the slider member, thus making the slider member adopt a failsafe locked condition.

A person outside the building cannot access the locking pin, since it is concealed inside the outer frame, and is protected by the slider member (where recessed holes 20 are provided).

Referring to figures 5, 6 and 7 of the accompanying drawings, there are shown parts of a second locking means, including a second locking pin assembly 130, and a barrel lock 131 with extending actuation pin 133 and key 132, in operable engagement. The second locking pin assembly comprises a housing 108, a compression spring 134, and a locking pin 121.

Referring to figure 5, the second locking pin assembly is in a first operating position, in which the barrel lock is in a first rotational position such that the actuation pin 133 allows a bias spring 134 to push the locking pin into an extended position for engaging a slider member (slider member not shown in fig 5-7). In the extended position, a head portion 120 of the locking pin protrudes from the housing to a first extent.

Referring to figure 7, the second locking pin assembly is in a second operating position in which the barrel lock is in a second rotational position such that the locking pin is drawn down into a retracted position in which it disengages the slider member. In the retracted position the head 120 extends from the housing to a second extent.

The dimensions of the first and second extents may be adjusted to suit the thickness of track, thickness of slider member, and positioning of the housing in the frame.

Referring to figures 8 to 10, there is shown a second locking pin embodiment, comprising an extending head portion 120, which in this embodiment is shown as cylindrical, but which in other embodiments may be square, and a body portion 121 having an ovoid shaped through passage or aperture 123, for accepting an engaging member which, in use, extends from the lock barrel to actuate the locking pin in an upward or downward direction.

Referring to figures 11 to 14 of the accompanying drawings, there is shown a housing 108 comprising a cylindrical wall 109 defining a hollow container portion having a open upper end 110, and a base 118, the wall having an ovoid shaped aperture 114 therein, exposing the inside of the container portion. A fixing plate 112 is provided, with two countersunk holes 115 suitable for accepting screws, eor fixing the housing to a wall of a window frame.

Referring to figure 15 of the accompanying drawings, parts of the second locking means are shown schematically installed in an outer frame 200 of a window. The outer frame is in this example of solid construction.

The barrel lock 131 fits into a first hole 201 which is drilled, or otherwise formed eg in manufacture of the frame, in a horizontal direction, transverse to the upward and downward directions of operation of the locking pin 121. The housing is inserted into a similarly formed hole 203 which extends in a downward direction. Where the housing and lock barrel are cylindrical, installation of the locking means into an existing frame can be made by drilling just two cylindrical holes using a conventional drill bit, the first hole having a horizontal main axis, and the second hole having a vertical main axis. The barrel lock and associated extending actuation pin are fitted into the first hole, and the housing, locking pin and spring are fitted into the second hole. A recessed channel may be cut in an upper surface of the frame to accommodate the upper plate of the housing.

In Figure 15, the locking pin is shown in an extended position, in which the head of the pin protrudes above the upper surface of the track 204.

Whilst a solid outer frame has been shown herein, by appropriate formation of apertures in the outer walls of a hollow frame member, the components may be fitted to a hollow outer frame, using conventional spring clips to attach the barrel lock to the wall of the frame, and using self tapping screws to attach the plate of the housing to an upper wall of the hollow frame.

Referring to Figures 16 and 17 of the accompanying drawings there is shown an end bracket for fitment to a wooden window, and Figures 18 and 19 show a rivet for fitting to a lug 300 of the end bracket.

Referring to Figures 20 to 23 of the accompanying drawings, there is shown a housing 301 for a pin 302. The housing is recessed in the window frame, underneath a track. The pin 302 is shown in Figures 22 and 23 in side and end view respectively.

Figures 24 and 25 of the accompanying drawings show in plan view and side view a cover for a lock housing; Figure 26 shows in plan view another embodiment of a slider member. Preferably this version of the slider member is around 150mm long and has three 4.0mm holes drilled along a centre axis of the slider member. A recess 304 is provided around 20mm from one end.

Figure 27 shows a channel for a window.

Figures 28 and 29 show an arm for an internal tilt turn side fitting.

Figures 30 to 32 show a further version of a slider member. This version is preferably of length around 42mm, and is provided with first and second holes 310, 311 each having a recess 312, 313 respectively provided on an underside 314 of this ladder member. The slider member is also provided with a further hole 315, having adjacent a bevelled channelled recess 316.

The first and second holes 310, 311 are provided for fitment of the support arms pivotally thereto, and the hole 315 with bevelled channel 316 is provided for accommodating a spring loaded pin, to lock the slider member to a track. Preferably the slider member has a width of around 13mm at a lower portion thereof and a width of around 9.25mm at an upper portion thereof. The upper portion is preferably of height around 1.5mm, whereas the lower portion is preferably of height around 3.5mm. The recesses are preferably of diameter lOmm, whilst the first and second holes are preferably of diameter around 5mm. The hole 15 is preferably of diameter around 6mm, and is positioned with its central axis around 13mm from one end of the slider member.

The first and second holes are preferably provided with their central axes at around 7.5mm, and l9mm respectively from the other end of the slider member.

Figures 33 and 34 of the accompanying drawings show a lock extension, for extending the operating length of the lock. The lock extension may be cut to length to suit various sizes of window frame. Preferably the lock extension is initially of length around 45mm. The lock extension is cylindrical and hollow, and provided at one end with a square recess 320 into which a square plug on one end of a lock can be fitted. The walls around the square plug may be fitted with a passage 321 for fitment of a 2mm roll pin, for locking the end of the lock into the lock extension. Preferably the square recess extends around 9.5mm along the length of the extension.

Figures 35 and 36 show schematically operation of a lock cam.

Figures 37 and 38 show schematically further embodiments of screw or roll pin embodiments for operating the locking pin by operation of a rotational lock.

Figures 39 and 40 show schematically a further embodiment of a locking pin. The locking pin comprises of three cylindrical sections, the first cylindrical section of diameter around lOmm and thickness 4mm. Connected thereto is a second cylindrical portion of diameter around 6mm and length around 7mm, and connected to the second cylindrical portion is a third cylindrical portion of length around lOmm and diameter around 4mm. The first cylindrical portion is provided with first and second flat sides 330, 331 of length around 6mm, such that the first portion is not truly cylindrical.

Referring to Figures 41 and 42, there is shown an aperture plate for the locking pin of Figures 39 and 40.

The third section of the locking pin protrudes from an aperture 340 in the aperture plate. In use, the aperture plate is recessed into a window and screwed to the window through screw holes 341, 342.

Figures 43 and 44 of the accompanying drawings show in plan and side view a support arm for a wooden window.

The support arm may be used to support a wooden inner frame to a PVC outer frame, or to support a PVC inner frame to a wooden outer frame. Preferably the support arm is of length around 150mm and thickness around 2mm. A first 5mm diameter hole is provided at around 6mm from one end of the support arm, while a second 6mm diameter countersunk hole is provided at another end of the stay arm.

Figures 45-47 show a further embodiment of a pin housing for use with various embodiments of the invention.

Figures 48-53 show a lock housing, to house a lock according to a further specific embodiment of the invention. The lock housing comprises a barrel 350 and a mounting plate 351. In use, the mounting plate is secured into a recess in either a wooden or PVC window frame, and a lock is inserted into the barrel 350. The plate 351 is secured to the frame by inserting screws into screw holes 352, 353. The barrel is shown in end view in Figure 48, and is provided with elongate channels which run along the length of the barrel to prevent rotation of a lock casing within the lock housing.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A hinge for a window having an inner and outer frame, the hinge comprising: an elongate track which is attachable to one of said inner or outer frames; a closure member which is attachable to the other one of said inner or outer frames; means for movably connecting the closure member to the track such that the closure member can swing away from or towards the track, the connecting means including a first support arm having one end pivotally attached to the track and another end pivotally attached to the closure member and at least one further support arm having a first end pivotally attached to the closure member, and a second end slidably attached to the track so as to be slidable along the track; and locking means for locking the closure member to the track in one or more predetermined orientations; wherein said second end of the further support arm is lockable in any of one or more positions along the track by operation of the locking means.

2. A hinge according to claim 1, in which said connecting means further comprises a slider member which is retained to the track and which is slidable along the track.

3. A hinge according to claim 2, in which said second end of the further support arm is attached to the slider member and the slider member is lockable in any of one or more positions along the track.

4. A hinge according to any one of the preceding claims, wherein the locking means comprises a locking pin adapted to move in a direction transverse to a direction of movement of the slider member, and one or more holes defined in the slider member, wherein the locking pin is arranged to engage with a said hole for locking the slider member in a corresponding locked position with respect to the track.

5. A hinge according to claim 4, in which the locking means is capable of being incorporated substantially inside the inner or outer frame so as to be substantially concealed from view.

6. A hinge according to claim 5, in which the locking means and track are adapted for fitment to the inner or outer frame such that, in use, the locking pin is arranged to pass from the respective inner or outer frame and through an aperture in the track to engage in a said hole in the slider member.

7. A hinge according to any one of the preceding claims in which the locking means is key operated.

8. A hinge according to any one of the preceding claims which is operated by a push-button.

9. A hinge according to any one of the preceding claims, in which the locking means comprises a barrel lock.

10. A hinge according to any one of the preceding claims in which the locking means comprises a housing for carrying a locking pin, the housing comprising a floor part and an upwardly extending wall part.

11. A hinge as appendant on claim 4, in which the locking pin is biassed into engagement with a said hole.

12. A hinge according to any one of the preceding claims in which the locking means is substantially concealed in a frame of the window.

13. A hinge according to any one of the preceding claims having a removable key.

14. A hinge according to claim 13, in which said key is a double sided key.

15. A hinge according to any one of claims 4 to 14, in which the slider member has means for adjusting a frictional force between the slider member and the track, so as to adjust a stiffness of opening of the inner frame with respect to the outer frame.

16. A hinge according to any one of the preceding claims in which the connecting means further comprises a third support arm having one end pivotally connected to the slider member and another end pivotally connected to the first support arm.

17. A hinge according to claim 14, in which said connecting means further comprises a fourth support arm having one end pivotally connected to the closure member, and another end pivotally connected to the third support arm.

18. A window provided with a hinge according to any one of the preceding claims.

19. A method of securing a window fitted with a hinge according to any one of the preceding claims, to an inner or outer frame of a window, the method comprising the steps of: forming a first hole in the inner or outer frame; fitting a said locking pin assembly into said first hole, such that a locking pin is capable of moving between an extended position or a retracted position, movement between the said positions being along an upright axis; forming a second hole in the inner or outer frame; fitting a lock into the second hole, the lock being arranged to engage the locking pin assembly such that a movement of the lock about an axis transverse to the upright axis causes a corresponding movement of the locking pin between the extended and retracted positions.

20. A method according to claim 19, wherein the movement of the lock about the transverse axis includes a rotational movement between a first rotational position and a second rotational position.

21. A method of securing a window or a method of fitting a locking means to a window substantially as herein described with reference to the accompanying drawings.

22. A hinge for a window, the window having an inner frame and an outer frame, the hinge comprising an elongate track which is attachable to one of said inner or outer frames; a carriage mechanism connecting the inner frame to the outer frame, and for carrying the inner frame on the outer frame in an opening or closing movement of the inner frame, the carriage mechanism being pivotally connected to the inner and outer frames, and pivotally connected to the elongate track, such that the carriage is arranged to be slidable along a length of the track; and locking means for locking the carriage to the track in one of a plurality of pre-determined carriage position.

23. A stay assembly for a window or door having an inner frame and an outer frame, said assembly comprising: an elongate track which is attachable to one of said inner or outer frames; a first slider member arranged to slide along said track; a locking means for locking said first slider member to said track in one slider member position or any one of a plurality of slider member positions along said track; and a first stay arm having a first end attached to said slider member and a second end attachable to the other one of said inner or outer frames; wherein said inner frame can be locked to said outer frame in one frame position or any one of a plurality of frame positions corresponding to said one slider member position or any one of a plurality of said slider member positions.

24. A stay assembly according to claim 23 further comprising a second slider member attachable to said inner or outer frame; and a second stay arm, wherein said second stay arm has one end connectable to said second slider member and another end connectable to said first stay arm.