Patent ID: 12215874

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS.1-3show a first embodiment of a castellated support structure1in the form of a mat. The mat may take the form of sheets that can be laid adjacent to one another or a roll that can be rolled out onto a desired surface. Either way the mat can be cut to size and shape for any particular installation.

The mat1is typically used as an intermediate structure in underfloor heating installations and provides a structure around which a heating element can be wound while holding the heating element in place. The mat1also provides a rigid structure that can protect the heating element from being damaged, e.g. crushed during installation by installers walking around on the mat1.

While the remainder of this description discusses a heating element in an underfloor heating installation, it will be appreciated that the mat is equally useful for a cooling element such as a conduit to carry a cold fluid and absorb heat from the room. It will also be appreciated that the installation is not limited to floors, but could equally well be installed on a wall or ceiling. It will also be appreciated that underfloor heating systems can either be fluid-based (often termed hydronic) in which a hot liquid is pumped through a fluid carrying conduit, or electrical in which an electrical current is passed through a heating wire to generate heat. The mat1can be used for any of these installations. The heating conduit, cooling conduit or heating wire are generally referred to as a thermal element.

FIG.1shows a support structure (mat)1with a thermal element (an electrical heating wire in this particular embodiment)2which is flexible and which has been laid in channels3,4which are formed between projections5. The projections have a side wall6with a height greater than the diameter of the thermal element2so that the channels3,4are deeper than the thermal element2and the thermal element2is thus fully accommodated in the channels3,4. The thermal element2thus lies underneath the upper surface of the mat1and is protected from footfall on top of the mat1.

As can best be seen inFIG.2, the channels3,4are undulating in the sense that the constrictions that form each channel3,4are not all perfectly in line, but rather are offset alternately in opposite directions when viewed along the length of the channel3,4. Therefore a thermal element2laid in the channel3,4undulates back and forth across a mid-line of the channel3,4as it is deflected by the projections5on either side of the channel3,4. This undulation allows the thermal element2to be held in contact with the side walls6of a number of the projections5, but without being pinched between them and without requiring overhanging lips to hold the thermal element2in the channel3,4. Instead, the channel3,4can be formed to be wider than the diameter of the thermal element2, thus avoiding pinching, while still ensuring that the thermal element2is contacted on both sides thereby holding it securely within the channel3,4. Without such grip on both sides there is a risk that the thermal element2could pop out of the channel3,4which is inconvenient as it requires relaying of the thermal element2and also risks damage to the thermal element2underfoot while not protected in a channel3,4.

For added security, i.e. for better retention of the thermal element2within the channel3,4, it is preferred that a small recess7is provided on the projections5at the point of contact with the thermal element2. This recess ensures that as the thermal element2is diverted around the projection5, it sits in the recess7and is thus retained from above by a part of the projection5that overlies the thermal element2. Note however that as this recess7is only ever present on one side of the channel3,4at one time and as the channel3,4is wider than the thermal element2, the thermal element2is not pinched as it is pressed down into the channel3,4and thus does not suffer any potential damage during this process.

The portion of the thermal element2that lies in channel4ainFIG.2is caused to undulate by four projections5which have been labeled A, B, C and D inFIG.2. The projections A and C lie on one side of the thermal element2, deflecting it in one direction (towards the top of the page), while projections B and D lie on the opposite side of the thermal element2, deflecting it in the opposite direction (towards the bottom of the page). Therefore, with reference to the page ofFIG.2, the thermal element undulates from left to right over projection A, under projection B, over projection C and under projection D. The contact points of the projections A, C interleave with those of projections B, D along the length of the thermal element2. It can be appreciated from this illustration that the outer radius of each projection A, B, C, D forms the inner radius of the undulations of thermal element2placed in channel4a. The outer radius of the thermal element2does not make contact with the projections that are adjacent to it (best seen inFIG.4).

As can be seen inFIGS.1and2, two sets of undulating channels3,4are formed the first set3is perpendicular to the second set4. The first set of channels3comprises a number of substantially parallel channels, e.g.3a,3b,3c. Similarly, the second set of channels4comprises a number of substantially parallel channels, e.g.4a,4b,4c. The term “substantially” here allows for the fact that adjacent channels in a set or not exactly parallel. For example, in the design ofFIGS.1-3, the undulations in two adjacent channels3a,3bare a mirror image of each other such that they undulate towards and away from each other as they pass along the length of the mat, i.e. there are points in adjacent channels that are closer together than other points in the same adjacent channels. Thus the adjacent channels3a,3b(and also4a,4bor3b,3cor4b,4c) are not exactly parallel.

The two sets of channels3,4together encompass a rectangular grid8which is shown inFIGS.1-3by way of illustration but need not actually take any form or be marked on the mat1in any way. The grid8is formed from straight lines at right angles to each other and illustrates the relative positioning of the projections5and how they form the undulating channels3,4. Looking at the grid line that lies in the channel4aat the top ofFIG.2, it can be seen that the left-most projection5athat lies above the grid line is much closer to the grid line than the two left-most projections5b,5cthat lie below the grid line. Together these three projections5a,5b,5cform the left-most constriction that defines the channel4a. The next left-most constriction is again formed by three projections5d,5e,5f, but this time projection5dlies below the grid line while projections5eand5flie above it and the projection5dbelow the grid line is much closer to the grid line than the two projections5e,5fabove it. Thus these two left-most constrictions are centered on opposite sides of the grid line and hence cause the channel4ato undulate or oscillate along the grid line as it passes from left to right.

The projections5are arranged in pairs. For example projections5band5cform a pair. Similarly projections5eand5fform a pair. Each pair of projections5lies between two adjacent channels of the first set of channels3and also between two adjacent channels of the second set of channels4. Each projection5of the pair forms a contact point on a channel3,4such that the two projections5of the pair form contact points on adjacent channels3,4of one set of channels, but not both. Thus if a pair of projections5form contact points on a channel of the first set3, they do not form contact points on a channel of the second set4and vice versa. Recesses7are formed at these contact points as discussed above. Each pair of projections is thus together slightly elliptical, having a wider dimension between the outer radii of the two projections5that form contact points with the adjacent channels (and have recesses7formed therein) than the dimension that does not contact the perpendicular channels.

The two projections5of a pair are curved such that each forms an arc around a central region9. The two projections5of each pair are separated from each other so as to form a pathway10into the central region9. These pathways10allow heat to be conducted from the thermal element2more evenly across the surface of the mat1as a whole, avoiding cold spots that might otherwise be formed between channels3,4. The curved nature of the projections5allows them to guide the thermal element smoothly between channels3of one set and channels4of the perpendicular set, thus allowing changes of direction of the thermal element2so that it can be laid back and forth across the mat1to cover a whole floor.

It may be noted that the rectangular grid8lies entirely within the channels3,4, i.e. the undulations caused by the projections5do not cause a thermal element2placed within the channel3,4to deviate by more than the width of the thermal element2. This puts a restriction on the amplitude of the undulations so as to minimize the stress placed on the thermal element2, while also minimizing the increase in length of thermal element2that is required by the undulations but also ensuring that the thermal element2is still securely held in place.

As can best be seen inFIGS.1and2, the projections5can be arranged into pairs in two different orientations so that one orientation provides contact points with one set of channels3, while the other orientation provides contact points with the other set of channels4. The projections5are arranged such that these two orientations are interleaved like the squares of a chequerboard, e.g. with one orientation occupying the black squares and the other orientation occupying the white squares. Thus each pair is directly adjacent (on the opposite side of a single channel) to a pair of the other orientation.

FIG.4ashows a cross-section taken through two adjacent pairs of projections5and showing the thermal element2in contact with the projection5dwhile not being in contact with the projection5f. The thermal element2(e.g. heating wire) is seated in recess7in the outer diameter of curved projection5dand is therefore constrained from upwards movement by the vertical overlap of the thermal element2and the projection5formed in this region. It can be seen that the thermal element2is not constrained by any similar overlap on the opposite side, i.e. adjacent to projection5f.FIG.4bshows a similar view, but taken at an angle (along the line IV-IV inFIG.2) rather than substantially parallel to the channel4so as to take a section through the narrowest point of the channel between the outer radius of the large-radius part of one projection and the outer radius of the small-radius part of an adjacent projection (on the opposite side of the channel3). It can be seen inFIG.4bthat the thermal element2is narrower than this narrowest part of the channel, i.e. the thermal element2is in contact with the large radius of the projection on the right, but there is a gap between the thermal element2and the small radius of the projection on the left.

FIGS.5-7are similar toFIGS.1-3, except that for clarity the thermal element2is not shown in these figures.FIG.7is a side view looking down the length of channels3. It will be appreciated that from this viewpoint two rows of pairs of projections can be seen, one behind the other. The wider dimension of a pair of projections in the rear row can be seen extending out beyond the narrower dimension of a pair of projections in the front row. This is highlighted on the right hand side ofFIG.7where reference numeral6′ shows the vertical side wall of the projection in the front row, while reference number7′ shows the recess in the side wall of the projection in the rear row. It can clearly be seen that the width of the projection5between side walls6′ in front is less than the distance between the recesses7′ of the pair of projections behind.FIGS.5-7also show perforations11that are formed through the support structure1so as to provide a liquid transfer path from one side to the other of the support structure1. These perforations11allow any adhesive that is applied above the support structure1to dry out by losing moisture through the perforations11. As in existing installations, any evaporation path that allows moisture to escape upwards, e.g. between tiles, is still viable.

However, the perforations11allow wet-type adhesives to be used even when there is no (or there is insufficient) moisture escape route upwards from the support structure. Instead, moisture can escape by travelling across the membrane support structure1from a top side (tile side or floor side) to the bottom side (sub-floor side) and can escape through normal moisture escape paths e.g. through a wooden or concrete sub-floor structure.

The perforations11are formed in the structure1by punching or drilling through the finished structure. Thus the perforations11are formed through the support structure1itself as well as through any stress mitigation layer formed on the underside thereof (as best seen inFIG.7). For example where a fabric layer such as a fleece layer12is formed on the back of the support structure1, the perforations pass through the support structure1(typically plastic) and through the fabric layer12. The diameter of the perforations11is kept sufficiently small that these through-holes do not allow adhesive to pass through from the top to the bottom and form a rigid connection across the support structure1. Such a rigid connection would prevent the stress-mitigation layer from accommodating relative movement of the support structure1and the sub-floor, e.g. due to thermal expansion variations. The perforations are no more than 2 mm in diameter to ensure no such rigid connection.

As is shown inFIGS.5-7, numerous perforations may be used to make up for their small size, regularly distributed across the surface of the support structure1. In the embodiment ofFIGS.5-7the perforations are formed along one set of channels3at a rate of three perforations per pair of projections5(i.e. two perforations between each perpendicular channel of the second set4and one on the intersection of perpendicular channels). However, it will be appreciated that this is purely an example and any other number and/or arrangement of perforations could equally well be used.

FIGS.8-10are similar toFIGS.1-3, except that for clarity the thermal element2is not shown in these figures. Also,FIG.10is a cross-section through the support structure1rather than a side view as this better shows the construction. The different hatchings on the cross-section illustrate the different pairs of projections (the different orientations being represented by different hatching).

FIGS.8-10illustrate an alternative toFIGS.5-7(although the two techniques could be used together) which uses larger holes13for transferring moisture from one side of the support structure1to the other side. The larger holes13can have a larger area than the perforations11and can thus allow a faster rate of moisture transfer across the structure1. However, a larger area hole means that there is a risk of adhesive bonding across the structure1which could prevent the stress-mitigation layer from operating correctly. Thus the larger holes13are formed only through the support structure1and not through the stress mitigation layer12(in this embodiment a fabric (fleece) layer bonded to the underside of the support structure1). As the stress mitigation layer12remains unbroken, adhesive from the upper side of the structure1is prevented from bonding to the underlying sub-floor and thus the stress-mitigation layer remains in place to accommodate relative movement due to differing thermal expansion.

In order to allow the holes13to be formed without damage to the stress mitigation layer12, the holes13are formed in projections14which project away from the stress mitigation layer12. As a gap is present between the upper surface of the projection14and the stress mitigation layer12, it is easy to cut, drill or otherwise rupture the top of the projection14without at the same time damaging the stress mitigation layer12. In this embodiment the projection14is a separate projection formed in the central area9between each pair of projections5, i.e. one such projection14can be formed for every two projections5on the mat1.

In use, when adhesive is applied to the upper surface of the support structure1, the adhesive can flow through the holes13where it collects between the stress mitigation layer12and the underside of the projection14. This has an additional benefit of providing a good bond between the adhesive layer and the support structure1.

FIG.11shows a close up of a pair of projections5with perforations11formed in the support structure1.FIG.12shows a close up of a pair of projections5with an additional projection14and hole13formed therein.FIG.13shows an alternative version ofFIG.12where instead of a single hole13, a plurality of smaller holes13′ are formed.

FIG.14shows another alternative toFIGS.12and13. Instead of forming the hole13(or holes13′) in a dedicated projection, holes13″ are formed in the tops of the main projections5. These holes13″ can be formed particularly quickly and easily for example by cutting across the mat1after forming. However, the end result, while perfectly practical, is less aesthetically pleasing and for this reason may be less preferred.

FIG.15shows a variation in which a single large projection15is used in place of a pair of projections5. All features of this single large projection15may be the same as for the combination of the pair of projections5except that there are no paths10to conduct heat into the central region of the projection15. The single large projection15has the advantage of allowing a very large hole16to be formed in the top thereof for very efficient transfer of moisture across the structure1.

FIG.16shows a textured version of the support structure21which is identical to the support structure1discussed above except with the addition of a textured upper surface (the surface that contacts the thermal element in use). The texture may be provided by adhering particles such as fibres to the surface of the mat. Fleece fibres are particularly suitable for this texturing and provide a keyed surface for good bonding of adhesive to the mat21.

It will be appreciated that other variations and modifications may be made to the examples described above while still falling within the scope of the appended claims.