GB2367852A

GB2367852A - Thermal break for locking together aluminium sections

Info

Publication number: GB2367852A
Application number: GB0120297A
Authority: GB
Inventors: Roger Emsley
Original assignee: BOAL UK Ltd
Current assignee: BOAL UK Ltd
Priority date: 2000-08-23
Filing date: 2001-08-21
Publication date: 2002-04-17
Anticipated expiration: 2021-08-21
Also published as: GB0120297D0; GB0020729D0; GB2367852B

Abstract

The thermal break, primarily for locking together aluminium sections 1,2 used in doors, windows and roof systems and for use in refrigerated cabinets, displays and vehicles where each of the pair of sections includes a longitudinal groove, comprises a plurality of u-shaped members 3 that each include a base and a pair of parallel end portions adapted to each be received into one of the grooves in the sections so that the sections are aligned in parallel and separated by a longitudinal gap. A plurality of locking members 5 are each adapted to be tightly received into the longitudinal gap so as to lock the end portions of the u-shaped members into the grooves, with the u-shaped members and the locking members being spaced apart from one another along the length of the grooves/gap. The locking member may have a rectangular or T-shaped cross-section and may be inserted into the longitudinal gap from either the same direction or the opposite direction as the u-shaped member is inserted into the longitudinal grooves. The base portion of the u-shaped member may be provided with a hole for receiving a threaded screw which passes into the longitudinal gap and the locking member may be integrally formed with the u-shaped element. The u-shaped member may be formed with ribs or nibs for engaging the longitudinal grooves and may be formed from a plastics material or a metal such as aluminium or rust-protected steel.

Description

TITLE Thermal Break System DESCRIPTION Field of the Invention The invention relates to a thermal break system for use in the locking together of aluminium sections. Such thermal breaks can be used in a variety of products, including domestic and commercial doors and windows and roof systems, and structural members for refrigerated containers, such as refrigerated display cabinets or refrigerated transport vehicles.

Prior Art When joining together aluminium sections to form structural members, it has long been recognized that it is advantageous to create a thermally insulating barrier between a section that will be located on the outside of a building and one that will be located on the inside. Such a thermally insulating barrier is known as a thermal break, and is itself an integral part of the structural member being assembled, as it must not detract from the rigidity of the whole.

The most popular thermal break system is known as the 'pour and cut'system. The same system is sometimes referred to as the'fill and de-bridge system'. An aluminium extrusion is created with a longitudinal pocket or cavity into which a thermo-setting resin is poured or injected. The aluminium base of the pocket or cavity is then cut away for example by milling, to separate the structural member into two discrete parts of aluminium each having an extrusion profile which gives it structural strength. The two parts are however joined by a bridge of the thermo-set resin which has a lower thermal conductivity than the aluminium and therefore provides the thermal break. One great disadvantage of the pour and cut thermal break system is that the resin pouring operation and to a greater extent the cutting away of the aluminium base of the pocket is a specialist operation which is normally out of the scope of the small or medium sized enterprises who make the architectural products or refrigerated containers in which the aluminium structural members are to be used. All stock therefore has to be sent out to a specialist firm for the creation of the thermal break, and this adds inevitably to the cost of the final product.

Another well established thermal break system is that known as the pclyamide thermal break system. The aluminium sections are made in two separate parts, for exposure to relatively low and relatively high temperatures respectively. For example, for a window or door frame one part would be an interior member and the other would be the exterior member. Both parts are formed with a dovetail or other re-entrant groove such that the two housings face one another on assembly. A continuous extrusion of polyamide has profiles formed along its opposite edges to be received in the respective facing grooves, so that when the polyamide extrusion is fed along the grooves the assembled whole comprises the two aluminium profiles held apart by the polyamide bridge which provides the thermal break. The polyamide thermal break system suffers from the same disadvantage as the 'pour and cut'system in that the assembly is a specialist operation. The fit between the aluminium sections and the polyamide must be a good one in order for the assembly to have the desirable rigidity, and specialist equipment is needed to extrude the polyamide to the necessary degree of accuracy and to force the extruded polyamide along the grooves in the aluminium. There is therefore a need for a thermal break system which permits assembly in the relatively small workshops which are typical of the relevant end-user industry.

US-A-3925953 discloses one such thermal break. Two aluminium sections which are to be joined together to form the structural member are each provided with a groove so that on assembly the grooves face in mutually opposite directions. A continuous extrusion of a thermally insulating material is generally C-shaped in section, so as to define two mutually facing edges which in use are received in the longitudinal grooves of the aluminium sections. This extrusion need not be as accurately formed as the polyamide extrusions referred to above. When the two aluminium sections are assembled with the C-shaped extrusion received with its edges in the longitudinal grooves, a longitudinal gap is formed between the two aluminium sections. Into this gap is forced a continuous extrusion which is of wedge section. The continuous extrusion wedges apart the two aluminium sections so that each of the inwardly facing edges of the C-shaped longitudinal connecting member is fully received in its respective groove.

The resulting assembly is rigid. On one side of the aluminium sections the continuous C-shaped member straddles the two sections and enters the grooves, and on the other side, the gap between the aluminium sections is informally filled along the whole of the longitudinal length by the wedge-shaped member. The C-shaped member and the wedge can be made of thermally insulating material, and it has always been believed that a thermal break system such as that of US-A-3925953 would provide the best possible thermal break characteristics consistent with the necessary rigidity of the assembly.

The Invention The inventor has found that surprising improvements in the thermal insulation of a thermal break such as that described above can be made without associated loss of rigidity. Moreover additional advantages can accrue, such as ease of assembly and reduced quantities of material in the final product. The invention provides a thermal break for locking together a pair of aluminium sections, each section having a longitudinal groove, the thermal break comprising: a plurality of U-shaped members each having a base portion and a pair of parallel end portions adapted to be received, one into each of the longitudinal grooves such that the sections are aligned in parallel and separated by a longitudinal gap; and a plurality of locking members each adapted to be tightly received into the longitudinal gap so as to lock the end portions of the U-shaped members into the longitudinal grooves; CHARACTERIZED IN THAT the plurality of U-shaped members are longitudinally spaced from each other along the longitudinal grooves, and the plurality of locking members are longitudinally spaced from each other along the longitudinal gap. The longitudinal grooves of the two aluminium sections preferably enter the sections from the same plane, so that in the direction of their depth they extend parallel to one another and parallel to the gap formed between the two aluminium sections, as opposed to extending in mutually opposite as in US-A-3925953.

The improved thermal insulation characteristics of the thermal break of the invention, in comparison with those of the prior art, reside in the fact that the U-shaped members and locking members are spaced apart along the longitudinal length of the aluminium sections. Thus most of the thermal insulation is provided by the air gap between the aluminium sections, with the straddling of that air gap by the U-shaped members and by the locking members being only intermittent. Air is a particularly good thermal insulator, and the thermal insulation achieved by establishing an air gap between the two aluminium sections can be substantially superior to that provided by continuous strips of plastic or rubber as in the prior art. Indeed the thermal insulating properties of air are such that a thermal break according to the invention can have thermally insulating properties that are substantially superior to the prior art even when the U-shaped members and/or the locking members are made of a thermally conductive metal such as aluminium or steel. The steel, if used, is preferably rust-protected for example by being galvanized. Preferably, however, one or both such members are made of a thermally insulating material such as a plastics material. A pair of aluminium sections can be assembled together far more easily using a thermal break according to the invention than the prior art. The U-shaped members can be pressed into the aligned grooves from one side of the air gap separating the aluminium sections, and the locking members can be inserted into the longitudinal gap from the same side or from the opposite side. Where access from the same side is required, one preferred construction is for the base portion of each U-shaped member to be provided with a hole through which is screw-threaded an associated locking member which is an externally threaded screw. The screw may be a standard No 6 self-tapping screw. Such screw threaded locking members in use pass through the holes of the U-shaped members and into the longitudinal gap where they are tightly received, biting into the aluminium sections and forcing them apart so as to lock the end portions of the U-shaped members into the longitudinal grooves.

If the locking members are to be simply pressed into the gap rather than screw threaded as described above, then they are advantageously T-shaped in cross-section, so that the user can press on the head of the T section while the stem of that section is received in the gap between the aluminium sections.

Each locking member can also be formed as an integral part of each U-shaped member. In this case, the U-shaped member may include a locking portion adapted to be tightly received into the air gap between the aluminium sections.

If the air gap is wide then instead of a single locking portion the U-shaped member preferably includes a pair of spaced resilient locking legs. The locking legs are received into the air gap but and are preferably provided with a retaining nib for snap fit engagement with a face of the aluminium sections. The integrally formed thermal break is preferably a snap fit in the longitudinal grooves and the end portions of the U-shaped members can be provided with a retaining nib for snap fit engagement with a complementary retaining nib provided in each of the grooves.

Drawings The drawings illustrate a variety of architectural aluminium sections utilizing thermal break systems according to the invention. It will be understood however that the shape of the aluminium sections can be varied to suit the end use while retaining the same thermal break system to establish thermal insulation between the aluminium sections of each assembled pair. Figure 1 is a cross section through a pair of aluminium sections and a'location-fit'U-shaped connecting member during assembly of a thermal break system according to a first embodiment of this invention; Figure 2 is a cross section through the thermal break system of Figure 1 showing a locking member being inserted to complete the assembly; Figure 3 is a cross section through a system according to Figure 1 but slightly modified in that it accepts as a locking member a screw inserted from the same side as the U-shaped member and passing through a base portion of the U-shaped member; and Figure 4 is a perspective view of an assembled product having a preferred thermal break system according to the invention, and showing the direction of insertion of the U-shaped members and locking members of the thermal break system; Figure 5 is a cross section through a pair of aluminium sections and a'snap-fit'integral U-shaped connecting member and locking member during assembly of a thermal break system according to a second embodiment of the present invention; and Figure 6 is a cross section through a system according to Figure 5 but slightly modified to deal with situations where the air gap between the pair of aluminium sections is wide.

Referring first to Figure 1, a first aluminium section 1 and a second aluminium section 2 are shown linked together by a U-shaped member 3. The U-shaped member 3 has a base 3a and mutually parallel leg portions 3b and 3c which are received one in a longitudinal groove la of the aluminium section 1 and the other in a parallel longitudinal groove 2a of the aluminium section 2. The U-shaped member 3 has a total axial length of only from 10 to 100 mm, and a number of such U-shaped elements are provided along the length of the aluminium sections 1 and 2, at spacings of from 200 to 350 mm. For most of their length, therefore, the aluminium sections 1 and 2 are therefore separated by an air gap 4 with no material at all spanning that air gap. The U-shaped members 3 are a location fit in the grooves la and 2a, with the location fit being enhanced by the formation of longitudinal ribs (unreferenced but clearly visible) from the outwardly and inwardly facing surfaces of the end portions 3b and 3c of the U-shaped members 3. This location fit enables the structure to be assembled as shown in Figure 1.

Figure 2 shows the insertion of locking members 5 to complete the assembly. Each locking member 5 is generally rectangular in section, with chamfered edges to assist insertion into the air gap 4. Each locking member is from 10 to 100 mm long, and the spacing between adjacent locking members is generally from 200 to 350 mm. Thus the thermal bridge between the aluminium sections 1 and 2 exists for only a very minor proportion of the overall length of the aluminium sections, and the passage of heat energy through that thermal bridge can be minimized by making one or both of the U-shaped member and the locking member 5 from a thermally insulating material such as plastics material.

The locking member 5 is preferably such a tight fit that the longitudinal teeth on the U-shaped members 3 facing inwardly towards the locking members 5 dig into the aluminium of the aluminium sections 1 and 2. Two important functions of the (unreferenced) longitudinal ribs on the end portions 3b and 3c of the U-shaped members are that when the assembly is complete as shown in Figure 2 the inwardly facing ribs bite into the-aluminium of the sections 1 and 2 to enhance the rigidity of the assembly; and most importantly that an air gap is created between the facing surfaces of the end portions 3a and 3b of the U-shaped member 3 and the cooperating faces of the aluminium sections 1 and 2. In other words the ribs bite a part of the way into the aluminium but not so deeply that the end portions 3b and 3c are brought into continuous face-to-face contact with the associated sides of the grooves la and 2a. Figure 3 illustrates an alternative locking member 6, with the remainder of the assembly being largely as illustrated in Figure 1. The locking member 6 of Figure 3 is a metal screw-threaded member which is inserted through a screw-threaded hole in the base portion of the U-shaped member 3 and into tight engagement with the aluminium sections 1 and 2 so as to force them apart and against the parallel arms of the U-shaped members 3 to create a rigid assembly. The screw threaded locking members 6 must be inserted from beneath as illustrated in Figure 3, from the same direction of insertion as the U-shaped members 3. In contrast, the locking members 5 of Figure 2 can be inserted from either above or below.

Figure 4 illustrates the joining together of the two aluminium sections 10 and 11 with a'location-fit'thermal break assembly generally as described above with reference to Figures 1 and 2. The particular thermal break components of Figure 4 do however represent a preferred aspect of the invention. A U-shaped member 13 has a base portion 13a and two parallel end portions 13b and 13c which are received in grooves lia and 12a of the aluminium sections 10 and 11 respectively. Although not shown in Figure 4, the U-shaped members preferably have longitudinal sharp ribs identical to those illustrated but unreferenced in Figures 1 and 2. A locking member 15 is received in the air gap 14 between the aluminium sections, and is inserted from the same direction as the U-shaped members 13. The locking members 15 are of T-shaped section, so that they can more easily be pressed into the air gap 14.

Figure 5 illustrates an alternative'snap-fit'thermal break in which the U-shaped member and the locking member are integrally formed as a single piece. The thermal break has a base 3a and mutually parallel leg portions 3b and 3c which are received one in a longitudinal groove la of an aluminium section 1 and the other in a parallel longitudinal groove 2a of an aluminium section 2. The thermal break has a total axial length of only from 10 to 100 mm, and a number of thermal breaks are provided along the length of the aluminium sections 1 and 2, at spacings of from 200 to 350 mm. For most of their length, therefore, the aluminium sections 1 and 2 are separated by an air gap 4 with no material at all spanning that air gap. Instead of using a separate locking member to complete the assembly the thermal break of Figure 5 has a central locking leg 7 which is tightly received within the air gap 4.

The leg portions 3b and 3c are formed with retaining nibs 3d. When the thermal break is pressed into place the leg portions 3b and 3c flex outwards until the retaining nibs 3d engage behind complimentary retaining nibs lb and 2b provided in the longitudinal grooves la and 2a. This snap fit enables the structure to be assembled as shown in Figure 5. To further increase the rigidity of the assembly an adhesive may optionally be applied in the space between the leg portions 3b and 3c and the locking leg 7.

Figure 6 illustrates an alternative pair of resilient locking legs 8, with the remainder of the assembly being largely as illustrated in Figure 5. The pair of locking legs 8 can be used to replace the central locking leg 7 (Figure 5) in situations where the air gap 4 between the aluminium sections 1 and 2 is wide. The pair of locking legs 8 are received within the air gap 4 and extend the full depth of the aluminium sections 1 and 2. Each locking leg 8 is terminated in a retaining nib 9. When the thermal break is pressed into place the locking legs 8 flex inwards until the retaining nibs 9 engage with a face of the aluminium sections 1 and 2 as shown in Figure 6. A screw-threaded member (not shown) can also be inserted through a screw-threaded hole (not shown) in the base of the U-shaped member 3 and into tight engagement with the locking legs 8 so as to keep them apart to create a rigid assembly. Although the'snap-fit'thermal breaks shown in Figures 5 and 6 have integral U-shaped members and locking members, it will be understood that the U-shaped members 3 illustrated in Figures 1 to 4 can also be made to be a snap fit in the longitudinal grooves la and lb. It will also be understood that the central locking leg 7 and the pair of resilient locking legs 8 can be provided on the U-shaped members 3 illustrated in Figures 1 to 4.

Generally speaking, the location fit is preferable to the snap fit when the leg portions 3b and 3c of the U-shaped member need to be especially rigid and cannot easily flex to enable the retaining nibs 3d to engage with the retaining nibs lb and 2b provided in the longitudinal grooves la and 2a.

The cross-sectional profile of the longitudinal grooves la and 2a may change along the length of the aluminium sections 1 and 2. Parts of the longitudinal grooves la and Ib may have retaining nibs Ib and 2b and other parts may have a smooth cross-sectional profile as illustrated in Figures 1 to 4. This profile change allows a combination of'snap-fit'and'location-fit'thermal breaks to be used to join together the two aluminium sections 1 and 2.

Claims

CLAIMS 1. A thermal break for locking together a pair of aluminium sections, each section having a longitudinal groove, the thermal break comprising: a plurality of U-shaped members each having a base portion and a pair of parallel end portions adapted to be received, one into each of the longitudinal grooves such that the sections are aligned in parallel and separated by a longitudinal gap; and a plurality of locking members each adapted to be tightly received into the longitudinal gap so as to lock the end portions of the U-shaped members into the longitudinal grooves; CHARACTERIZED IN THAT the plurality of U-shaped members are longitudinally spaced from each other along the longitudinal grooves, and the plurality of locking members are longitudinally spaced from each other along the longitudinal gap.
2. A thermal break according to claim 1, wherein the locking members have a rectangular cross-section, taken perpendicular to the longitudinal axis.
3. A thermal break according to claim 1, wherein the locking members have a T-shaped cross-section, taken perpendicular to the longitudinal axis.
4. A thermal break according to any preceding claim, wherein the locking members are receivable into the longitudinal gap from the opposite side of the aluminium sections to the side from which the U-shaped members are receivable into the grooves.
5. A thermal break according to claim 1, wherein the locking members are receivable into the longitudinal gap from the same side of the aluminium sections as the side from which the U-shaped members are receivable into the grooves.
6. A thermal break according to claim 5, wherein the base portion of each U-shaped member is provided with a hole and wherein each locking member is an externally threaded screw which in use passes through one of the holes and into the longitudinal gap.
7. A thermal break according to claim 5, wherein each locking member is formed as an integral part of each U-shaped member.
8. A thermal break according to claim 7, wherein the U-shaped members include a locking portion adapted to be tightly received into the longitudinal gap so as to lock the end portions of the U-shaped members into the longitudinal grooves.
9. A thermal break according to claim 7, wherein the U-shaped members include a pair of resilient locking portions each provided with a retaining nib for snap fit engagement with a face of the aluminium sections.
10. A thermal break according to any preceding claim, wherein the end portions of the U-shaped members are provided with a retaining nib for snap fit engagement with a retaining nib provided in each of the longitudinal grooves.
11. A thermal break according to any preceding claim, wherein the locking members are made of plastics material or a metal such as aluminium or rust-protected steel.
12. A thermal break according to any preceding claim, wherein the oppositely facing end portions of the U-shaped members include one or more ribs for engagement with the longitudinal grooves.
13. A thermal break according to any preceding claim, wherein the U-shaped members are made of plastics material or a metal such as aluminium or rust-protected steel.
14. A thermal break according to any preceding claim, wherein the U-shaped elements have a longitudinal length of from 10 to 100 mm.
15. A thermal break according to any preceding claim, wherein the locking elements have a longitudinal length of from 10 to 100 mm.
16. A thermal break according to any preceding claim, wherein the plurality of U-shaped elements are longitudinally spaced from each other along the longitudinal grooves by from 200 to 350 mm, and the plurality of locking members are longitudinally spaced from each other along the longitudinal gap by from 200 to 350 mm.