Improved hinge for folding leaf systems

Abstract

A compressible hinge is provided for a folding leaf system, which allows additional expansion / contraction of the leaves in order to improve sealing. The hinge comprises a slotted leaf having a vertical slot; a pin slidably located in the vertical slot; a pinned leaf mounted on the pin such that the pinned leaf is both rotatable about the pin, and slidable along the vertical slot between a compressed condition and an extended condition. 20 24 21 97 04 13 S ep 2 02 4 A B S T R A C T 2 0 2 4 2 1 9 7 0 4 1 3 S e p 2 0 2 4 8 / 11 FIG. 6 28 36 32 34 30 16 38 40 40 42 39 41 o ;o o & $ o ;o Q Q 'ey o 8 / 11 16 41 42 30 40 34 40 28 38 36 39 D 32 FIG. 6 20 24 21 97 04 13 S ep 2 02 4 3 2 3 0 4 0 4 0 2 8 3 8 3 9 2 0 2 4 2 1 9 7 0 4 1 3 S e p 2 0 2 4

Description

FIELD OF THE INVENTION The present invention relates to an improved hinge for a folding leaf system. More particularly, but not exclusively, it relates to an improved hinge for aluminium folding leaf systems and / or a folding leaf system fitted with such hinges. BACKGROUND OF THE INVENTION Folding doors (sometimes known as bifolding doors) are a popular option for allowing access to an exterior outdoor space such as a deck or patio. Similar folding panel arrangements are sometimes applied to windows or to interior doorways, and collectively such designs can be referred to as folding leaf systems. Folding leaf systems are made up of multiple panels which are hinged such that they can fold concertina-style when the folding leaf system is open and sit flush with the frame when closed. Many configurations are possible that vary the mounting arrangement and the number of panels and hinges. Typically, folding leaf systems (at least of the exterior type) are made of extruded joinery, for example aluminium, with a track at the top and / or bottom of the frame which can guide rollers attached to one or more of the panels. Rubber seals may be used to provide some level of sealing and / or protection against water ingress when the folding leaf system is closed. One problem with folding leaf systems (in particular those of the exterior type) is that because of the sealing action and the tight fit of the panels when closed, the bifolding door can sometimes require a substantial force to begin opening the door or to finish closing it. This is exacerbated by expansion of the door panels due to changes in temperature, which becomes especially problematic for large frames that require a long span of multiple panels. Large temperature and / or moisture changes due to weather conditions, in combination with tight seals needed to protect from changeable weather, can thus make exterior folding leaf systems frustratingly difficult to open and close. It is thus desirable to find alternative configurations for folding leaf systems which can make them easier to open and / or close, while still maintaining excellent sealing performance. In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless 2024219704   13 Sep 2024 stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art. For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence. It is an object of the present invention to provide an improved hinge for a bifolding door which overcomes or at least partially ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice. BRIEF DESCRIPTION OF THE INVENTION According to a first aspect the invention broadly comprises a compressible hinge for a folding leaf system, the hinge comprising: a slotted leaf comprising a vertical slot; a pin slidably located in the vertical slot; a pinned leaf mounted on the pin such that the pinned leaf is both rotatable about the pin and slidable along the vertical slot between a compressed condition and an extended condition, wherein the slotted leaf is mountable to a frame of the folding leaf system and the pinned leaf is mountable to a hinged panel of the folding leaf system, or vice versa. According to another aspect the invention comprises a biasing mechanism which biases the pinned leaf towards the extended condition. According to another aspect the biasing mechanism comprises at least one biasing member. According to another aspect the biasing member is mounted to the slotted leaf. According to another aspect the biasing member bears on the pin. According to another aspect the slotted leaf comprises an internal horizontal passage which extends into the vertical slot, the biasing member being mounted within the internal horizontal passage. According to another aspect the biasing member is a coil spring. 2024219704   13 Sep 2024 According to another aspect the pinned leaf can slidably move between 4 mm and 30 mm between the compressed condition and the extended condition. According to another aspect the pinned leaf can slidably move between 5 mm and 15 mm between the compressed condition and the extended condition. According to another aspect the pinned leaf captures the pin from both above and beneath the vertical slot. According to another aspect the pinned leaf is generally C-shaped. According to another aspect the slotted leaf and the pinned leaf each present a mounting face having mounting holes to facilitate fastening to the frame or the hinged panel. According to another aspect the vertical slot extends orthogonal to the normal direction of the mounting face of the slotted leaf. According to another aspect when the compressible hinge is mounted in the folding leaf system, movement of the pinned leaf between the compressed condition and the extended condition accommodates for shrinkage or growth of panels of the folding leaf system. According to another aspect the compressible hinge accommodating for shrinkage or growth of the panels thereby reduces the extent to which such shrinkage or growth is accommodated by flexible seals that seal between the frame and the panels when the folding leaf system is closed. According to another aspect the invention broadly comprises a folding leaf system comprising: a frame; two or more panels connected such that they are concertina-foldable, including a hinged panel and a leading panel; and two or more compressible hinges as claimed in any one of claims 1 to 15, wherein the compressible hinges are connected between the frame and the hinged panel on one side of the frame, and a leading edge of the leading panel can be moved towards an opposite side of the frame to close the folding leaf system. According to another aspect the invention comprises a plurality of flexible seals that seal between the frame and the panels when the folding leaf system is closed. 2024219704   13 Sep 2024 According to another aspect the plurality of flexible seals include at least one flexible seal between the frame and the leading edge of the leading panel. According to another aspect the plurality of flexible seals are rubber strips. According to another aspect the frame comprises a top roller track and / or a bottom roller track. According to another aspect each roller track guides at least one roller, each roller being mounted on the leading panel or on at least one intermediate panel connected between the hinged panel and the leading panel. According to another aspect the panels and the frame comprise extrusions. According to another aspect the extrusions are aluminium. According to another aspect the slotted leaf of each compressible hinge is mounted to the frame and the pinned leaf of each compressible hinge is mounted to the hinged panel. According to another aspect each compressible hinge is mounted such that the vertical slot extends parallel the frame. According to another aspect the pinned leaf of each compressible hinge is mounted to the frame and the slotted leaf of each compressible hinge is mounted to the hinged panel. According to another aspect the folding leaf system is an exterior folding door. According to another aspect the folding leaf system is a folding window. According to another aspect three compressible hinges are connected between the frame and the hinged panel. According to another aspect the invention comprises a method of improving the ease of opening and closing a folding leaf system, the method comprising connecting the compressible hinges of any one of the previous clauses between the frame and the hinged panel of the folding leaf system. According to another aspect connecting the compressible hinges involves replacement of existing hinges of the folding leaf system. Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings. As used herein the term "and / or" means "and" or "or", or both. 2024219704   13 Sep 2024 As used herein "(s)" following a noun means the plural and / or singular forms of the noun. The term "comprising" as used in this specification and claims means "consisting at least in part of". When interpreting statements in this specification and claims which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example only and with reference to the drawings in which: Figure 1A    shows a perspective view of the folding leaf system when closed; Figure 1B    shows a perspective view of the folding leaf system when nearly closed; Figure 1C    shows a perspective view of the folding leaf system when fully open; Figure 2A    shows a perspective cutaway view of the folding leaf system when open; Figure 2B    shows a perspective cutaway view of the folding leaf system when closed; Figure 3A    shows a top cross-section view of the folding leaf system when nearly closed; Figure 3B    shows a top cross-section view of the folding leaf system when closed; Figure 4      shows a tree diagram of various configurations of the folding leaf system; Figure 5A    shows a top view of the compressible hinge in the compressed condition; Figure 5B    shows a top view of the compressible hinge in the extended condition; Figure 6      shows a perspective exploded view of a compressible hinge with a biasing mechanism; Figure 7 shows a perspective exploded view of a compressible hinge without a biasing mechanism; Figure 8A shows a top cross-section view of a folding leaf system with a reversemounted compressible hinge when the folding leaf system is nearly closed; and Figure 8B shows a top cross-section view of the folding leaf system with the reversemounted compressible hinge when the folding leaf system is closed. Figure 9 shows a top cross-section view of the reverse mounted compressible hinge folding leaf system showing offset hinges. Figure 10 shows a top cross-section view of the reverse mounted compressible hinge folding leaf system showing un-equal length leaves. 2024219704   13 Sep 2024 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS According to various aspects of the various embodiments of the present invention as illustrated in figures 1A-10, there is provided a compressible hinge 16 for a folding leaf system 10 which will now be described. The function of the compressible hinge 16 is for its pivot axis to be slidably moveable between a compressed condition and an extended condition instead of being fixed as with a typical hinge, as will subsequently be explained in more detail. This allows the hinge 16 to provide additional compliance to a folding leaf system 10, thereby supplementing the compliance provided by the (typically) flexible rubber seals 18. A "folding leaf system" as it relates to the present invention is herein defined to mean any system having concertina-foldable panels that can be opened and closed within a frame 12, including at least folding doors (sometimes known as bifold doors) and folding windows. Preferably the folding leaf system 10 is of the exterior type i.e. separating an interior space from an exterior space, because this is the context in which sealing and temperature fluctuation are especially relevant considerations. However, the present invention could also be utilised with interior folding doors. Further, it is envisioned that the folding leaf system may open inwardly, or outwardly as desired. In many typical configurations, outwardly opening systems may be preferred. However, in other configurations, for example where security doors are fitted outward of the bi-fold system, and inwardly opening system will be necessary (and vice versa). Although the compressible hinge 16 is the key aspect of the invention, the folding leaf system 10 as fitted with compressible hinges 16 will first be described for context. It will be appreciated that the folding leaf system 10 may be of largely conventional design except for the compressible hinges 16, the hinges 16 being mounted between the frame 12 and a hinged panel 14. As shown in figures 1A-1C, the folding leaf system 10 comprises a frame 12, a hinged panel 14, and compressible hinges 16 connected between the frame 12 and the hinged panel 14. It will be appreciated that the hinged panel 14 is the first panel in a concertina-foldable set of panels, along with at least a leading panel 15. The folding leaf system 10 comprises at least two compressible hinges 16 to properly support the hinged panel 14, and higher numbers (e.g. three hinges 16 as shown) may be used to provide further 2024219704   13 Sep 2024 support. Higher numbers of hinges 16 may require more careful alignment to function correctly. Preferably, the frame 12 further comprises at least one roller track 20, each roller track guiding at least one roller 22 mounted on the panels. The at least one roller track 20 could include a top roller track and / or a bottom roller track. The rollers 22 are shown mounted on the leading panel 15 at its leading edge 19, but mounting locations of the rollers 22 will depend on the configuration of the folding leaf system 10 as will be described in more detail. The rollers 22 may engage the roller track(s) 20 horizontally or vertically, for example with a wheel or a ball, and may be mounted in any suitable way e.g. via a pivoting connection as shown. Rollers 22 help to ensure proper concertina-folding action of the panels by guiding them in the frame 12 as the folding leaf system 10 opens and closes, while the track provides support (at least for example against drooping). As shown in Figures 2A-2B, the folding leaf system 10 preferably comprises flexible seals 18 fitted between the frame 12 and the hinged panel 14 to seal therebetween when the folding leaf system 10 is closed. The flexible seals 18 are shown mounted on the frame 12 but could be mounted on the hinged panel 14 with equivalent effect. The flexible seals 18 may be rubber strips, or any other suitable compressible material. As shown in Figures 3A-3B, flexible seals 18 may be present at other locations of the folding leaf system 10, for example in between the panels (i.e. adjacent inter-panel hinges 24 which connect the door panels together) and between the leading panel 15 and the opposite side of the frame 12. It will be appreciated that the flexible seals 18 (particularly those that seal against the frame 12) provide some compliance and / or compressibility to the folding leaf system 10 upon opening and closing. Typically, this type of compressible seal can provide up to around 5mm of compressibility while maintaining good sealing performance (especially over time). However, for some folding leaf systems, this degree of compressibility is insufficient. For example in some preferred configurations more movement needs to be accommodated, e.g.: • where the total opening is large, and / or • the panel geometry requires more movement (e.g where panels are short). 2024219704   13 Sep 2024 As shown in Figure 4, there are numerous possible configurations of the folding leaf system 10, having various arrangements of panels. Compressible hinges 16 are suitable for use with at least all the configurations shown, as well as other variations. In some configurations, the folding leaf system 10 comprises one or more intermediate panels connected between the hinged panel 14 and the leading panel 15, which may be suited to wider doorways / windows. In some configurations the leading edge 19 of the leading panel 15 closes against the opposite side of the frame 12, while in others it closes against another panel which is mounted on the opposite side of the frame 12. In some configurations the folding leaf system 10 has two groups of concertina-foldable panels mounted opposite each other such that the leading edges 19 meet in the middle (or elsewhere between the edges of the frame depending on configuration - see Fig 4) as the folding leaf system 10 closes (this may be referred to as a bi-parting folding leaf system). Regardless of configuration, the folding leaf system 10 is characterised by at least one group of panels concertina-folding as the folding leaf system 10 opens, and the leading edge 19 of the leading panel 15 moving towards an opposite side of the frame 12 (relative the compressible hinges 16) as the folding leaf system 10 closes. For a group of concertina-folding panels, rollers 22 are preferably mounted at points that will lie in-plane with the frame 12 when the folding leaf system 10 is open. This may include locations on the leading panel 15, and also on intermediate panels. The panels and the frame 12 may comprise extrusions, preferably aluminium extrusions that are glazed as appropriate (typically double or triple glazed to provide the desired level of thermal performance). As shown in figures 5A-5B, the compressible hinge 16 comprises a slotted leaf 28 and a pinned leaf 34. The slotted leaf 28 comprises a vertical slot 30, which slidably locates a pin 32. In particular, the vertical slot 30 provides the pin 32 with a generally vertical axis, and the ability for the pin 32 to also translate in a generally horizontal direction. The pinned leaf 34 is mounted on the pin 32 such that the pinned leaf 34 is both rotatable about the pin 32 2024219704   13 Sep 2024 and slidable along the vertical slot 30 between a compressed condition (shown in Figure 3A) and an extended condition (shown in Figure 3B). Optionally, the compressible hinge 16 may further comprise a biasing mechanism which biases the pinned leaf 34 towards the extended condition. The biasing mechanism preferably comprises at least one biasing member 36, for example a coil spring as shown. This may assist in reinforcing the sealing action when the folding leaf system 10 is closed, and preventing accidental opening. As shown in Figure 6, the pin 32 is preferably long enough to extend both above and beneath the vertical slot 30. Thus, the pinned leaf 34 captures the pin 32 from both above and beneath the vertical slot 30. The pinned leaf 34 may be C-shaped to facilitate this type of mounting. There may be a vertical hole 42 in the pinned leaf 34 which allows the pin 32 to be inserted through both the vertical hole 42 and the vertical slot 30, which properly secures the pinned leaf 34 once appropriate fasteners are applied. Preferably the at least one biasing member 36 (if included) is mounted to the slotted leaf 28. Preferably it bears on the pin 32 to bias the pinned leaf 34. For example, the slotted leaf 28 may comprise an internal horizontal passage 38 which extends into the vertical slot 30, the biasing member 36 being mounted within the internal horizontal passage 38. The internal horizontal passage 38 may be threaded, such that the biasing member 36 can be retained inside by means of an end stop 39 screwed into the internal horizontal passage 38. The end stop 39 may also allow for adjusting the force of the biasing member 36, as screwing the end stop 39 further into the internal horizontal passage 38 may increase the baseline compression of the biasing member 36. As shown in Figure 7, the compressible hinge 16 could alternatively have no biasing mechanism 36, but be otherwise mostly identical (the internal horizontal passage can also be omitted). The slotted leaf 28 and the pinned leaf 34 may each present a mounting face having mounting holes 40 to facilitate fastening to the frame 12 or the hinged panel 14. 2024219704   13 Sep 2024 Optionally, each mounting hole 40 of the slotted leaf 28 may be covered by a cover 41 to conceal the fasteners after insertion, however this does not affect the function of the compressible hinge 16. Preferably each mounting face is substantially planar. The vertical slot 30 preferably extends orthogonal to the normal direction of the mounting face of the slotted leaf 28. Preferably, the slotted leaf 28 is mountable to the frame 12 of the folding leaf system 10 and the pinned leaf 34 is mountable to the hinged panel 14 of the folding leaf system 10. Mounting in this way can be considered a standard mounting configuration. However, a reverse mounting configuration is also possible i.e. the slotted leaf 28 may instead be mountable to the hinged panel 14 and the pinned leaf 34 may be mountable to the frame 12. If the mounting holes 40 and the corresponding mounting locations on the frame 12 and the hinged panel 14 are positioned appropriately, the compressible hinge 16 may be made reversible such that it can be mounted in either configuration without any changes to its design. In the standard mounting configuration, the mounting of the compressible hinge 16 is preferably such that the length of the vertical slot 30 extends parallel to the frame 12. This helps to ensure that the hinged panel 14 will correctly align with the frame 12 when the bifolding door 10 is closed, regardless of the position of the pin 32 within the vertical slot 30. This can be seen for example in Figures 2A-2B and 3A-3B. The reverse mounting configuration is shown in Figures 8A-8B. In this configuration the vertical slot 30 rotates during opening of the folding leaf system 10, such that the length of the vertical slot 30 changes in angle and no longer extends parallel to the frame 12. Although this may result in slightly different movement of the panels during opening / closing, correct alignment is still reached once the folding leaf system 10 is fully closed, and the function of the compressible hinge 16 is still achieved. It will be appreciated that this configuration will require adjustment to the folding leaf dimensions and or mechanism to ensure the kinematics of the bi-folding system operate correctly. 2024219704   13 Sep 2024 With reference to Figures 9 & 10, some alternative configurations for accommodating the kinematic requirements of the reverse hinge mounting configuration of figure 8 are shown. For example, Figure 9 illustrates additional offset hinges 50, in order to provide the necessary offset 51 required for the roller / guide to align with the track. Similarly, Figure 10 illustrates an alternative configuration with un-equal panel widths 52,53, in order to provide the necessary offset required for the roller / guide to align with the track. The ideal length of the vertical slot 30 (in either mounting configuration) may vary depending on the desired maximum compression for the compressible hinge 16, which will be correlated to the degree of panel growth expected given the size of the folding leaf system 10, the operating temperature range, the degree of opening / closing force desired, and / or the amount of compression provided by the compressible seals 18. Preferably, the pinned leaf 34 can slidably move between approximately 4 mm and 30 mm when transitioning between the compressed condition and the extended condition, and more preferably between 5 mm and 15 mm. For example, the length of the vertical slot 30 may be such that the centre-to-centre distance between the two positions of the pin 32 is approximately 8 mm. For one example of a folding door with two folding panels each having approximately 300 mm width, expected collective panel growth across a desirable operating temperature range is approximately 21 mm. However, this value will be sensitive to the exact design of the folding leaf system 10 and particularly the panel width. Although some of this 'growth' is accommodated by compression of the flexible seals 18, slidable movement of the pinned leaf 34 can help to accommodate additional 'growth' which is important for many modern bi-folding systems and especially where large frame openings are desired, and / or narrow panel widths. The primary benefit of the compressible hinge 16 is in improving the ease of opening and closing the folding leaf system 10, while still maintaining an adequate sealing action. By providing some translation allowance through movement within the hinge 16, the 2024219704   13 Sep 2024 compressible hinge 16 accommodates panel shrinkage / growth that may occur due to temperature change for example, that could result in difficulty in opening or closing the folding leaf system 10. The compressible hinges 16 will thereby reduce the extent to which panel shrinkage or growth is accommodated by the flexible seals 18, which may also widen the operating temperature ranges that are viable for a given design of folding leaf system because more growth can be accommodated before interference with the frame 12 occurs. The optional addition of a bias towards the extended condition can create force which ensures that there will still be sufficient seal compression of the flexible seals 18, and that the panels will not be loose (or too tight) in the frame 12. Compressible hinges 16 can be retrofitted to existing, conventional folding leaf systems (by replacing their existing hinges) to improve the ease of opening and closing, or most preferably they can be fitted in purpose-designed new folding leaf system installations where all components can be sized appropriately for the expected conditions and desired performance. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Claims

1. A compressible hinge for a folding leaf system, the hinge comprising:a slotted leaf comprising a vertical slot;a pin slidably located in the vertical slot;a pinned leaf mounted on the pin such that the pinned leaf is both rotatable about the pin and slidable along the vertical slot between a compressed condition and an extended condition,wherein the slotted leaf is mountable to a frame of the folding leaf system and the pinned leaf is mountable to a hinged panel of the folding leaf system, or vice versa.

2. The compressible hinge of claim 1, further comprising a biasing mechanism which biases the pinned leaf towards the extended condition.

3. The compressible hinge of claim 2, wherein the biasing mechanism comprises at least one biasing member, mounted to the slotted leaf.

4. The compressible hinge of any one of claim 2 or claim 3, wherein the biasing member bears on the pin.

5. The compressible hinge of claim 4, wherein the slotted leaf comprises an internal horizontal passage which extends into the vertical slot, the biasing member being mounted within the internal horizontal passage.

6. The compressible hinge of any one of claims 3 to 5, wherein the biasing member is a coil spring.

7. The compressible hinge of any one of the preceding claims, wherein the pinned leafcan slidably move between 4 mm and 30 mm between the compressed condition and the extended condition, or wherein the pinned leaf can slidably move between 5 mm and 15 mm between the compressed condition and the extended condition.

8. The compressible hinge of any one of the preceding claims, wherein the pinned leaf captures the pin from both above and beneath the vertical slot.

9. The compressible hinge of claim 8, wherein the pinned leaf is generally C-shaped.2024219704   13 Sep 202410. The compressible hinge of claim 9, wherein the vertical slot extends orthogonal to the normal direction of the mounting face of the slotted leaf.

11. The compressible hinge of any one of the preceding claims, wherein when the compressible hinge is mounted in the folding leaf system, movement of the pinned leaf between the compressed condition and the extended condition accommodates for shrinkage or growth of panels of the folding leaf system.

12. The compressible hinge of claim 11, wherein the compressible hinge accommodating for shrinkage or growth of the panels thereby reduces the extent to which such shrinkage or growth is accommodated by flexible seals that seal between the frame and the panels when the folding leaf system is closed.

13. A folding leaf system comprising:a frame;two or more panels connected such that they are concertina-foldable, including a hinged panel and a leading panel; andtwo or more compressible hinges as claimed in any one of claims 1 to 12, wherein the compressible hinges are connected between the frame and the hinged panel on one side of the frame, and a leading edge of the leading panel can be moved towards an opposite side of the frame to close the folding leaf system.

14. The folding leaf system of claim 13, further comprising a plurality of flexible seals that seal between the frame and the panels when the folding leaf system is closed, and wherein the plurality of flexible seals include at least one flexible seal between the frame and the leading edge of the leading panel.

15. The folding leaf system of claim 13 or claim 14, wherein the frame comprises a top roller track and / or a bottom roller track.

16. The folding leaf system of claim 15, wherein each roller track guides at least one roller, each roller being mounted on the leading panel or on at least one intermediate panel connected between the hinged panel and the leading panel.2024219704   13 Sep 202417. The folding leaf system of any one of claims 13 to 16, wherein the slotted leaf of each compressible hinge is mounted to the frame and the pinned leaf of each compressible hinge is mounted to the hinged panel.

18. The folding leaf system of any one of claims 13 to 17, wherein the pinned leaf of each compressible hinge is mounted to the frame and the slotted leaf of each compressible hinge is mounted to the hinged panel.

19. The folding leaf system of any one of the preceding claims, wherein the folding leaf system is an exterior folding door.

20. The folding leaf system of any one of claims 13 to 18, wherein the folding leaf system is a folding window.

21. A method of improving the ease of opening and closing a folding leaf system, the method comprising connecting the compressible hinges of any one of claims 1 to 12 between the frame and the hinged panel of the folding leaf system.

22. The method of claim 21, wherein connecting the compressible hinges involves replacement of existing hinges of the folding leaf system.

Images