IE86704B1 - Gasket - Google Patents

Abstract

A gasket of flexible, resilient material for a door or window has a sealing part 46a, 46b, 48 and an attachment part 24. The sealing part is designed such that, under increasing compressive force, it reaches a geometric lock configuration. Before geometric lock is achieved, the gasket deforms its shape under compression, straightening a convex linking wall 48 such that the wall 48 pushes connecting ends of two side walls 46a, 46b outwards. Once compressive force is sufficient to straighten the linking wall 48, the gasket shape resists further compressive deformation and so the gasket achieves a geometric lock. <Figure 1>

Description

Gasket This invention relates to a gasket made of a resilient material with longitudinally-extending profile, such as used in the sealing of windows, doors and the like.

A gasket is a mechanical seal that extends along the length of a window or door frame, protecting joins against the ingress of draughts, water and other weathering effects. The gasket will generally have to satisfy slightly different requirements depending on its application. A functioning window assembly, for example, will include a frame that is fixed to the building walls, a supporting sash that can open and close with respect to the frame, perhaps also transoms and multions and panes of glass or glazing units that are held within. The window unit (sash plus glazing) may move vertically against the frame, as in a sash window, or may be hinged to move inwards or outwards. This invention is primarily concerned with the latter configuration. A variety of different opening mechanisms are known: a reversible mechanism, tilt and turn mechanism, top and side hinged windows, etc. In any of these arrangements, there is one type of join that can be opened or closed, which is that between sash and frame, and another join that is permanently fixed to hold the glazing unit in place. In the first instance, the gasket is required to provide a dynamic seal; in the second a static seal.

A dynamic sea! must be sufficiently soft to allow the window to close tightly to form a seal about its periphery and relatively wide to provide a tolerance for manufacture and installation. A static seal on the other hand, in addition to sealing, is responsible for holding the glazing unit in place. It should therefore be relatively hard and resilient, with a strong seal being formed once it is compressed in position during and after installation.

There is currently a drive to provide window parts in a modular design ~2~ which allows great flexibility in assembly and installation of the window. Modern windows may mirror traditional designs, with transoms and mullions, or may be more contemporary with larger panes of glass. In all cases however, there is a desire to minimise the number of components that have to be manufactured. Many window manufacturers now produce a range of components (known as profiles) that, when assembled, may be located anywhere within the window system surround. That is, the profile may be used to form the frame, sash, transom or mullion. These interlock with a range of sill designs, glazing beads, ancillaries and the like to enable many different window designs to be readily installed.

Universal gasket designs that are capable of sealing regardless of function within the assembled window are known in the prior art. GB 2457338 describes a longitudinally extending gasket that has a sealing surface that comprises two portions: a first portion, running the length of the gasket, that extends outwards into the window rebate and a second portion, also running the length of the gasket, that extends from the end of this first portion across the remainder of the sealing surface. The first (smaller) portion is thicker and made of a material that is less flexible and more resilient than that of the second portion. This design enables the first portion to effect the seal when the gasket provides a static seal that holds a glazing unit and the second portion to effect the seal when the gasket provides a dynamic seal between sash and frame.

US 6,024,364 describes a gasket whose geometric profile, rather than material differences, is primarily responsible for enabling sealing of different sealing points on a window. The gasket is shaped to form two sections: a sealing pad and a sealing lip. When pressure is applied to the sealing iip, the sealing pad is pushed upwards. This results in raising of a part (nose strip) of the sealing pad, which then presses against the glass or window profile to form the seal, regardless of whether the seal is to be static or dynamic.

Although able to seal effectively in different frame locations, these prior art designs are not universal across different manufacturing techniques. The gasket of US 6,024,364 is designed to be pressed into a groove in a semifinished window, shortly after extrusion. That of GB 2457338 is designed to be co-extruded with the window profile. There is a perceived need for a new design of universal gasket, which ideally lends itself to a modular construction across a range of manufacturing processes. It is accordingly an object of the present invention to provide a novel gasket design that may be fitted to different window or door types and used to seal effectively at different locations within.

According to a first aspect of the invention, there is provided a gasket of flexible, resilient material for a door or window assembly, the door or window profile being either fixed or openable. The gasket extends longitudinally and comprises an attachment portion for location in a profile part and a sealing portion, the sealing portion comprising an open structure defined by the attachment portion, first and second side walls and a linking wall, wherein the side walls extend away from the anchor portion at their proximal ends to the linking wall at their distal ends, the linking wall having a bent region, the bent region contributing to the linking wall being generally convex and outwardly oriented with respect to the side walls.

The gasket is characterised in that the sealing portion is adapted such that as the gasket is compressed, the linking wall straightens, resulting in an outward movement of the distal ends of the side walls; and wherein on application of a threshold compression, at which the linking wall attains a straight alignment, the sealing portion becomes more rigid, whilst retaining its open structure. This rigidity results from the gasket structure reaching its limit of geometric deformability, which is termed a “geometric lock”.

This design of gasket profile is advantageous in that it is suitable for use in either a static or a dynamic seal. A particularly innovative aspect of this design is its ability to achieve a geometric lock. The geometric lock renders ~4~ the gasket stronger for applications in which a static seal is required, in the initial stages of gasket compression, the bent region is pushed inwards towards the attachment portion. This straightens the linking wall, which, in turn, pushes the distal ends of the side walls outwards. Their proximal ends are fixed in position, with the result that the side walls are pushed to a more oblique configuration. When the linking wall is straight, the gasket cannot change its shape any further in response to increasing compression. The side walls are in their most oblique orientation and further compression results only in material deformation, until the structure itself fails. Such failure limit is unlikely to be reached in normal use and the geometric lock has been achieved. In this locked position, the gasket effects a very strong seal, for example, between window sash and glazing unit. The same design of gasket may also be used to effect a dynamic seal, in which applied compression is insufficient for the gasket to reach a geometric lock. To form a dynamic seal, the gasket profile is simply compressed as the window or door is shut to effect a seal. On re-opening, the gasket relaxes back to its more open original configuration.

Some prior art gaskets may have structural similarities with those of the present invention, such as having two side walls and a linking wall, but no known gasket is able to form a geometric lock. For example, the gasket described in EP 2163720 includes thickened side walls and a z-shaped overlap in its linking wall, rather than simply a bend. As the gasket is compressed, the overlap will flatten, bringing the stronger side walls into contact with a frame or glazing unit to effect a seal. The side walls will not move outwards, if anything the flattening linking wall may pull the longer wall inwards. This gasket cannot therefore deform to a geometric lock.

GB 2411424 describes a gasket in which one side wall, the one that is to effect the seal, is shorter and thicker than the other. The linking wall includes a pair of folds and is designed to collapse when compressed, thereby bringing the thicker wall into sealing contact with a frame or glazing unit. The folded linking wall is too long and the side walls too short to allow ~ a geometric lock to develop.

In this invention, the geometric iock position is adopted when the gasket is under a threshold compression. When compressive force is below this threshold, the gasket responds substantially by way of geometric deformation. That is, by changing the shape of the gasket configuration. When under compression above the threshold, further geometric deformation is not possible and so any compressive force beyond this threshold is absorbed substantially by way of gasket material deformation.

The gasket of this invention has an additional advantage when in its geometric iock position: when forming a static seal, such as holding glazing in place, the line of the gasket is uniform. When visible therefore, the gasket has a neater, more even look, which is aesthetically more satisfactory than known in the prior art.

The bent region may be located centrally with respect to the side walls or offset towards one or other side wall. Further, it may be rounded or more sharply angled, for example adopting a V shape. The bent region may even be formed from two or more bends in the linking wall. The crucial aspect of this feature is that the bent region of the linking wall extends beyond a connecting line between the ends of the two side walls such that it transfers the initial stages of compression to an outward movement of the side waifs.

The gasket may include an internal wall, the internal wall located intermediate the two side walls and extending in a diagonal orientation from the attachment portion to the linking wall. Incorporation of an internal wall increases gasket rigidity, enabling it to exhibit more resistance to compression and better relaxation back to its original state when the compressive force is removed.

Firmness can be enhanced in embodiments in which the gasket further includes a second internal wall. The second interna! wall is also located intermediate the two side walls and extends in a second diagonal orientation from the attachment portion to the linking wall, the second diagonal orientation being symmetric with respect to the first.

Alternatively, the gasket may include an arrangement of internal walls located intermediate the two side walls. The internal walls extend from a central location to at least one point on the attachment portion and to at least one point on the linking wall, the at least one point on the linking wall being offset from that on the attachment portion.

The side walls may be oriented substantially parallel with each other. Alternatively they may diverge from each other, or even, in some embodiments, be inclined slightly towards each other, as they extend away from the attachment portion.

In further preferred embodiments the side walls may be of substantially equal length. The sealing portion may be of unitary construction, manufactured by extrusion of a resilient flexible material.

The linking wall ideally has a length that is less than the sum of the distance between the side walls at their proximal ends plus a/3 times the average length of the side walls. This limitation prevents the gasket being compressed too flat in its geometric lock, which would reduce the strength of the seal it could form. A weaker seal would make the gasket less effective in shielding against weather ingress. Similarly, when in its locked configuration, the side walls should converge at an angle of less than 120°. Preferably, they should converge at an angle within the range 10° - 50° and, ideally, 25° - 35° These values are the result of what is essentially a compromise reached in determining a preferred geometric lock position.

On the one hand, a smaller angle provides for more restraint from the side walls and hence a stronger seal. It is also less visible around a glass window. On the other hand, a wider angle means that the locked gasket is more resistant to knocks, particularly those tending to shear the structure. ~8 A window or door assembly process generally includes a number of stages. First the plastic, or other material, is extruded to form a length in the shape of the required profile, gasket or other component part. Fabrication then involves cutting the extruded profile, welding the parts together and, as necessary, fitting glazing and seals, to form the window or door outline.

The fabricated window or door is then transported and installed on site.

The gasket in accordance with this invention is particularly adaptable as it can be used with different manufacturing processes. The gasket may be co-extruded with a profile structure. It may be extruded after the profile and then attached prior to window or door fabrication. Alternatively, it may be extruded and then inserted in the profile during fabrication, or even during installation.

The attachment portion may comprise separated plugs that are located in complementary recesses in a sash structure or it may comprise a shallow plug for location in a gap defined between profile walls, the profile being coextruded with the gasket or the gasket being fixed to the profile in a postextrusion process.

Alternatively, the attachment portion may comprise a plug with peripheral rim, the plug being insertable into a recessed formation in a profile and held in position by the rim. This design makes the gasket most suitable for insertion in a recess in a sash or frame after extrusion. This can be during manufacture, fabrication or as part of the installation process.

The invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a cross sectional view of window profiles (sash and frame) incorporating four gaskets in accordance with this invention; Figure 2a is a cross sectional view of a glazing unit sealed within a frame using a gasket in accordance with a first embodiment of this invention, a second embodiment being shown in an adjacent position for comparative purposes; Figure 2b is an enlarged view of the two gasket embodiments of Figure 2a; Figures 2c and 2d illustrate the first gasket embodiment of Figure 2a as it is, respectively, relaxed and compressed to seal against a glazing unit; Figures 3a and 3b illustrate the gasket of Figure 2c as it is respectively, relaxed and compressed to seal against a frame; Figures 4 to 15 illustrate respective alternative embodiments of a gasket in accordance with this invention; Figures 16a and 16b illustrate the changing shape of a gasket as it is compressed to form a geometric lock; Figure 17 illustrates an arrangement of gaskets sealing at multiple locations in window profiles.

Figure 1 illustrates a typical window profile assembly 10 that incorporates the gasket of the invention. The assembly 10 shown in the diagram is intended to show the positions of the gasket and is not to be taken as limiting application of this invention to any particular window type. The drawing shows in cross-section a frame profile 12 that is fixed to a building wall (not shown). A lower sash part 14a of a T-shaped profile 14 is located in the frame profile 12 and an upper sash part 14b holds a glazing unit 16.

In most modern window designs the profiles 12, 14 are fabricated from extruded plastics material or lightweight metal such as aluminium, although they can also be of wood or steel. The glazing unit 16 is double glazed, with a pair 18a, 18b of glass panes.

A first pair 20, 22 of gaskets create a seal between frame 12 and sash 14a. In this position they provide a dynamic seal where the sash 14a meets the frame 12. The gaskets 20, 22 extend around the perimeter of the frame. That is, Figure 1 is a cross-sectional view that could be taken at the top, bottom or either side of the frame. In the diagram, each gasket 20, 22 is shown in both its relaxed (r) and compressed (c) condition. This is purely for illustrative purposes. When the window is fitted and closed, the gaskets 20, 22 will be compressed (c). When the window is open, they 20, 22 will be relaxed (r). The gaskets 20, 22 may be fabricated from a resilient flexible material such as an elastomeric polymer, rubber, silicone, PVC, neoprene, EPDM, etc.

Each gasket 20, 22 includes a wedge-shaped anchor 24 that can be pressed into a rebate area 26 within the sash or frame construction. The profiles 12,14 are manufactured, generally by extrusion, to include the rebate 26. The gasket 20, 22 may be inserted into the rebate 26 during installation with the frame attached to the window position or, alternatively, inserted towards the end of the manufacturing process and supplied fitted to an installer.

A third gasket 28 in accordance with the invention creates a seal between the frame part 14b of the T-shaped profile 14 and glazing unit 16 of Figure 1. That is, this gasket 28 is illustrated providing a static seal as the glazing meets the profile 14. Again, the gasket 28 extends the full perimeter of the profile. In the diagram, the gasket 28 is shown in both its relaxed (r) and compressed (c) condition. Again this is illustrative: the gasket 28 will be compressed when sealed against the glazing. The gasket 28 is of the same material construction as the dynamic-seal gaskets 20, 22 described previously. The gasket 28 also has an anchor wedge 24 that fits into a rebate 26 in the sash. In this embodiment, the gasket 28 is used to seal the outside of the window.

A glazing bead 30, of known design, is fixed to the profile 14 at the indoor side of the window. That is, Figure 1 illustrates an internally-beaded sash design. The gasket of this invention can be used in both internally-beaded and externally-beaded (with bead on the outdoor side) profiles. The glazing bead location is chosen according to application, but does not affect the gasket requirements at dynamic and static joins. The internallybeaded profile can be more secure against a potential intruder but the profile configuration (2-shaped profile) for an external bead is less complicated to fabricate and therefore quicker to produce.

The bead 30 includes a gasket 32 of conventional C-shaped design that seals against the inside pane of the glazing unit 16. The bead 30 is pushed into position during window manufacture and other known gasket designs, for example the flipper gasket, that facilitate this movement can also be used to seal the glass. Alternatively, the gasket of this invention may be used. The important consideration is to keep the gasket itself low to minimise protrusion beyond the profile 14 and therefore to maximise the area of glass that is visible in the window area. Alternative designs and shapes of glazing bead can equally be used to hold the glass secure in the window profile.

Figure 2a shows the gasket 28 and glazing bead 30 of Figure 1 as they are fitted in the frame profile 12 to seal the glazing unit 16. This arrangement is shown enlarged in Figure 2b. Components common to these figures and to Figure 1 are like referenced. Also shown in Figures 2a and 2b is a second embodiment 34 of the gasket. The gasket 34 in accordance with the second embodiment is shown supporting an adjacent region of glass, but this illustration is to allow ready comparison between the two designs 28, 34. In reality, either one or other design would be used alone in the position occupied by the first embodiment 28. This second embodiment 34 of the gasket of the invention differs from the first 28 in that it does not have the anchor wedge for insertion into a rebate. Instead it 34 has a base 12~ portion 36 that fits snugly into the same rebate 26 of the frame 12. The base portion 36 comprises a pair of rearward extending walls 38 with a cap 40. The diameter of the cap 40 is slightly larger than the diameter of the rebate 26 in order to ensure secure retention of the base 36 in the rebate. The snug fit is achieved by extruding the gasket 34 with the frame 12. This may be done by co-extrusion or by first extruding the frame 12, closely followed during the manufacturing process by extrusion of the gasket 34 (post-extrusion).

The availability of both extruded 34 and inserted 28 gasket embodiments of this invention in turn allows a choice of manufacturing process. The extruded gasket 34 may be attached to a profile at a very early stage (extrusion or post-extrusion) of the manufacturing process, which reduces work during the subsequent fabrication stage. On the other hand, extruding the gasket with the main profile increases the number of extrusion tools required. This initial increased outlay in tooling costs may favour the inserted gasket. The choice of gasket type will likely depend on manufacturing logistics and tooling costs. A gasket in accordance with this invention may be co-extruded, post-extruded or inserted.

The structure of the first embodiment of the gasket 28 and how it effects a static seal against the glass pane 18a will now be described in more detail with reference to Figures 2c and 2d.

Figure 2c shows the gasket 28 in its relaxed state at a position remote from corner regions of the profile. At corner positions, the gasket is cut on the diagonal and welded to a similarly cut portion to take it through a 90° turn. There will therefore be some local deformation at the corners. Elsewhere, the gasket 28 is hollow throughout its length. In cross-section, it is shaped to form a rear wall 44, that sits adjacent the profile to which it is attached, first 46a and second 46b side walls that extend away from the rear wall 44 and a forward portion 48 that links the two side walls 46a, b to form a sealing surface. The anchor wedge 24 referred to previously is located behind the rear wall 44.

In this embodiment 28 the side walls 46a, 46b extend parallel to each other and away from the rear wall 44. The forward portion 48 connects the ends of the side walls 46a, 46b to define an internal cavity 49 within the gasket. The forward portion is not straight, but includes a bend 50, in a convex orientation, such that the length of the forward portion 48 is longer than the distance separating the ends of the side walls 46a, 46b. The bend 50 forms a rounded apex that projects in the direction of the surface to be sealed. In this embodiment 28, the bend 50 is centrally located.

The anchor wedge 24 is a compressible construction of the same material as the gasket 28. it is formed of two parts: a rearward extending wedge portion 52 topped by a ridge cap 54. On insertion into the rebate 26, the cap 54 is compressed as it passes through the rebate opening and then expands to anchor the gasket 28 to the rebate 26. The wedge 24 also includes a cavity 56 to aid compression during insertion.

The anchoring wedge 24 of this embodiment is of unitary construction with the sealing part of the gasket. This can, of course, be varied and for some applications a harder material will be preferred for the anchoring wedge 24. A harder material will hold the gasket more securely in the profile. In either case, wedge and sealing portion may be co-extruded to form the gasket.

An additional refinement is to include an inextensible cord running longitudinally within the anchoring wedge 24. This cord (not shown) acts as an expansion limiter and helps prevent lengthening or shrinking of the gasket through the manufacturing process.

As the gasket 28 is compressed against a pane of glass 18a, the projecting bend 50 comes into contact with the glass 18a first. The bend 50 is therefore pushed inwards. As a result, in order to conserve length, the -14ends of the forward portion 48 are forced apart. This force is communicated to the side walls 46a, 46b. As the side walls 46a, 46b are each fixed in position at the profile side of the gasket, they will pivot about their fixed points, resulting in the walls 46a, 46b increasingly bending outwards. As compression continues, the side walls 46a, 46b move further apart at their forward ends until the forward portion 48 of the gasket forms a straight line. At this point the gasket structure is said to have reached a “geometric lock”. That is, the forward portion 48 cannot straighten any further and any outward movement of the side walls 46a, 46b will only continue if the material of the gasket itself is stretched. This will not happen to any significant extent under normal compressive loads that are experienced in window and door seals. This situation is illustrated in Figure 2d. Further compression of the glass 18a against the gasket 28 wilt therefore simply result in a greater force holding the gasket to the glass.

Figures 3a and 3b illustrate compression of the same gasket embodiment 20 as it effects a seal between sash 14a and frame 12. That is, the behaviour of the gasket as it forms a dynamic seal. The relaxed state, shown in Figure 3a is the same as shown previously in Figure 2c and so will not be described further. Compression of the gasket 20 also has the same result as described previously: the projecting bend 50 is pushed inwards as it comes into contact with the frame 12. The ends of the forward portion 48 are forced apart, which in turn forces the walls 46a, 46b to bend outwards. In this situation however compression does not continue until the geometric lock is achieved. Rather an adequate seal is achieved with a lesser compressive force and the seal is effected as shown in Figure 3b. As can be seen, the forward portion 48 still retains a slight convex shape.

It will be understood that the dual sealing function of the gasket 20, 22, 28 in accordance with this invention is based on the ability of the construction to adopt a geometric lock. That is, an applied compressive force initially distorts the geometry of the gasket, which can be achieved with relatively small forces. These forces are however sufficient to effect an adequate seal against openable window or door frames (Figure 3b). A far stronger seal is achieved once the gasket is distorted to its geometric lock. That is, geometric distortion is complete and any further compression can only be absorbed by material deformation. This requires a far stronger compressive force. In its geometric lock position, the gasket can be used to seal against a glazing unit (Figure 2d).

Further embodiments of the invention are shown in Figures 4 to 15. The embodiment 60 of Figure 4 has a different anchoring mechanism that is achieved by extruding the profile 14 and then post-extruding the gasket 60. In manufacturing a window that incorporates this gasket design, the profile structure is extruded with grooves running longitudinally along an inner side. The gasket is then extruded with complementary ridges formed on the ends of the gasket side walls that cooperate with the grooves in the sash structure. Alternatively, the ridge / groove structure may be directly bonded by co-extruding the gasket 60 with the profile 14. In another departure from previously-described embodiments, the side walls 46a, 46b are no longer parallel but extend outwards away from the central cavity of the gasket. In common with other embodiments of this invention however, the lock-out geometry is achieved when the central bend is compressed and straightened to 180°. The side walls 46a, 46b will be more oblique in this position than they were in the embodiment shown in previous Figures. The gasket 60 will however be more visible through the glass of the window, which is aesthetically less pleasing. A more aesthetically pleasing embodiment (not shown) may therefore be obtained if the side walls 46a, 46b lean slightly inwards when the gasket is in its relaxed configuration. Care has to be taken to limit the inward slope however in order to ensure that the walls 46a, 46b do not absorb the compressive force by distorting further inwards but instead are pushed outwards towards a geometric lock.

Figure 5 is an enlarged view of the alternative gasket embodiment 34 shown in Figures 2a and 2b. That is, it includes the rear walls and cap that hold the extruded gasket 28 in place within the rebate 26.

Figure 6 is a further embodiment of gasket 61 in which the bend region 50 is formed from two 50a, 50b separate bends in the forward portion 48 of the gasket. The bend region 50 still retains its convex orientation.

Another embodiment 62 of the gasket, with alternative profile attachment, is shown in Figure 7. In this embodiment the gasket 62 is post-extruded or co-extruded with the profile 14 and two rearward wails 63a, 63b abut and are directly bonded to walls 64a, 64b of the profile 14 structure. The bend 50 in the forward portion 48 of the gasket has a larger radius of curvature than for previous embodiments.

The embodiments 65, 66, 67, 68 shown in Figures 8 to 11 have an additional internal wall 70 inside the gasket cavity 49. In these embodiments the bend 50 of the forward portion 48 of the gasket is offcentre with respect to the side walls 46a, 46b. In cross-section, this wall 70 runs diagonally from the forward portion 48 to one side of the bend 50, behind the bend to the opposite side of the rear wall (if present) or other portion that is affixed to the profile. In any case, the internal gasket cavity 49 is now divided into two cavities of differing geometries. This design of gasket has an increased resistance to compression and faster recovery to its relaxed position once the compressive force is removed. On the other hand, it uses more material and is consequently more expensive. Alternatively, the same result can be achieved simply by including more material in the walls of the previously-described embodiments. As can be seen from the Figures, the wall 70 and bend 50 can be to the same side 68 of a central axis, or on opposing sides 65,66, 67. The side walls 46a, 46b can be parallel 67, or one, other or both can slope outwards 65, 66, 68 when relaxed. Any anchoring structure can be used without affecting the potential of the sealing portion to adopt a lock-out geometry.

Figures 12 to 14 illustrate embodiments 72, 74, 76 of the gasket in which two interna! walls are included. These assist further in strengthening the gasket and in aiding its restoration to a relaxed configuration when compression is removed, for example by opening the window. Conversely though, a stronger gasket can make it more difficult to close a window, which may not suit many users. As can be seen from the diagrams, the walls extend diagonally in either direction and may be separated 72, 76 or may cross 74. They accordingly divide the gasket cavity 49 into three or four internal compartments.

Finally, the embodiment 78 shown in Figure 15 also has internal walls for strengthening and increased resilience, but these walls are formed into a Yshaped arrangement.

Although the embodiments of gasket shown in Figures 4, 5 and 7 to 14 have the co-extruded or post-extruded anchoring structures, it is clear that these, along with the anchoring wedge used in inserted gaskets, are interchangeable. Similarly the inserted gasket anchoring structure of Figures 6 and 15 may be exchanged for a co- or post-extruded version. That is, any of the illustrated gaskets may be formed by extrusion with the profile or may be formed for insertion during manufacturing, fabrication or installation, with anchoring portion adapted accordingly.

It should be noted that the bend 50 in the forward portion 48 may be rounded to a greater or lesser degree. Moreover, it is not necessarily rounded and an angled bend, defining a V-shaped profile, could also be used. A single distinct bend may be apparent, or two or even more. It will be clear to one skilled in the art that all that is required is that, as the gasket is compressed, a compression force on the forward portion results in an outward movement of the side walls, until the structure becomes locked to 18~ a shape dictated by its geometry.

Figure 16a shows a basic gasket design in accordance with this invention, such as that illustrated in Figure 2c. Figure 16b shows the same gasket once its shape is locked geometrically. Consideration will now be given to designs of gaskets that are best suited for the window and door applications described herein. For this purpose, the exemplary gasket of Figures 16a and 16b is considered to have rear wall 44 of length b, side walls 46a, 46b of length w and forward wall 48 of total length f. The geometric lock is achieved when the side walls 46a, 46b are tilted such that they subtend an angle a, as shown in Figure 16b. At this position, the thickness (distance from rear wall to forward wall) of the compressed gasket is t.

At the locked position, the forward wall 48 is fully extended such that: a f = b + 2wsin — And the thickness of the gasket is given by: a t = w cos— The angle a at which the geometric lock is achieved to some extent dictates the performance of the gasket. If the length of the forward wall 48 is shorter, angle a will be smaller and less displacement of the side walls 46a, 46b will be required for the lock. This more vertical orientation of the side walls allows a stronger seal although, if the compressed thickness t of the gasket is too large, the locked gasket will be less stable and may have a tendency to skew if knocked or subject to further compression. Conversely, a longer forward wall 48 means that the side walls 46a, 46b, will fan out to a wider angle in forming the lock. Although more stable, the 19~ restraint from the side walls is decreased, making the seal less effective.

It is found that for the geometric lock to be at all effective, the angle a should be less than 120°. This in turn sets a maximum value for the length of the forward wall: b < f 1/2w. Generally though, the locking angle a in a practical gasket design will be significantly smaller than 120°, for example within the range 10° - 50°. Ideally, for incorporation of this gasket in PVCU window designs, the angle ot is between 25° and 35°. Of course, other angular ranges may result in gaskets whose performance at the lock position is more suited to other window designs or to different markets.

The side walls 46a, 46b are shown as being oriented perpendicular to the rear wall 44 in Figure 16a, for simplicity. As is made clear in the foregoing, the side walls 46a, 46b may slope inwards or outwards in their relaxed position. If they slope outwards then there will be less resistance to compression during the initial stages of sealing (dynamic seal) and less displacement required before the geometric lock is reached, assuming forward wall length f is unchanged.

It is also noted that f is the total length of the forward wail 48 regardless of the number of bends in the wall or of the symmetry of such bend(s).

Finally, Figure 17 illustrates the flexibility of window design using a modular system that includes gaskets in accordance with this invention. A T-profile 80 forms a sash against a Z-profile 82 fixed frame, in either a transom or mullion arrangement. Both profiles 80, 82 also hold glazing units 84, 86. Four gaskets 92 in accordance with this invention may be used to provide either static seals against the glazing units 84, 86 or dynamic seals between the profiles 80, 82.

Claims (22)

Claims

1. A gasket of flexible, resilient material for a door or window, the gasket extending longitudinally and comprising an attachment portion for location in a profile part and a sealing portion, the sealing portion comprising an open structure defined by the attachment portion, first and second side walls and a finking wall, wherein the side walls extend away from the attachment portion at their proximal ends to the linking wall at their distal ends, the linking wall having a bent region, the bent region contributing to the linking wall being generally convex and outwardly oriented with respect to the side walls, characterised in that the sealing portion is adapted such that as the gasket is compressed, the linking wall straightens, resulting in an outward movement of the distal ends of the side walls; and wherein on application of a threshold compression, at which the linking wall attains a straight alignment, the sealing portion becomes more rigid, whilst retaining its open structure, this rigidity resulting from the gasket structure reaching its limit of geometric deformation (geometric lock).

2. A gasket according to claim 1 wherein, with the linking wall straightened, the outward movement of the distal ends of the side walls results in the walls diverging at an angle a of less than 120°.

3. A gasket according to claim 2 wherein the angle a is in the range 10° 50°.

4. A gasket according to claim 3 wherein the angle a is in the range 25° 35°

5. A gasket according to any preceding claim wherein, the linking wall has a length that is less than the sum of the distance between the side walls at their proximal ends plus V3 times the average length of the side walls.

6. A gasket according to any preceding claim wherein the bent region is located centrally with respect to the side walls. 5

7. A gasket according to any one of claims 1 to 5 wherein the bent region is offset towards one or other side wall.

8. A gasket according to any preceding claim wherein the bent region is rounded.

9. A gasket according to any one of claims 1 to 7 wherein the bent region 10. Is angled to form a V-shape.

10. A gasket according to claim 8 or 9 wherein the bent region comprises two or more separated bends in the linking wall.

11. A gasket according to any preceding claim wherein the gasket includes an internal wall, the internal wall located intermediate the two side 15 walls and extending in a diagonal orientation from the attachment portion to the linking wall.

12. A gasket according to claim 11 wherein the gasket includes a second internal wall, the second internal wall also located intermediate the two side walls and extending in a second diagonal orientation from the 20 attachment portion to the linking wall, the second diagonal orientation being symmetric with respect to the first.

13. A gasket according to any one of claims 1 to 10 wherein the gasket includes, in profile, an arrangement of internal walls located intermediate the two side walls, the walls extending from a central 25 location to at least one point on the attachment portion and at least one point on the linking wall, the at least one point on the linking wall being offset from that on the attachment portion.

14. A gasket according to any preceding claim wherein the side walls are oriented substantially parallel with each other. 5

15. A gasket according to any one of claims 1 to 13 wherein the side walls diverge from each other as they extend away from the attachment portion.

16. A gasket according to any preceding claim wherein the side walls are of substantially equal length. 10

17. A gasket according to any preceding claim wherein the sealing portion is of unitary construction.

18. A gasket according to claim 17 wherein the sealing portion is manufactured by extrusion of a resilient flexible material.

19. A gasket according to any preceding claim wherein the gasket is co15 extruded with a profile structure.

20. A gasket according to any one of claims 1 to 18 wherein the attachment portion comprises separated plugs that are located in complementary recesses in a profile structure, the profile being coextruded with the gasket or the gasket being fixed to the profile in a 20 post-extrusion process.

21. A gasket according to any one of claims 1 to 18 wherein the attachment portion comprises a shallow plug for location in a gap defined between profile walls, the gasket being either co-extruded with the profile or extruded after profile extrusion and bonded or glued 25 thereto.

22. A gasket according to any one of claims 1 to 18 wherein the attachment portion comprises a plug with peripheral rim, the plug being insertable into a recessed formation in a profile and held in position by the rim.