Double-walled flue system
The polymer-based double-walled flue system addresses insulation and sealing issues with enhanced thermal performance and ease of assembly, offering a cost-effective and visually appealing solution for outdoor installations.
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- OLI SRL
- Filing Date
- 2025-12-01
- Publication Date
- 2026-06-03
Smart Images
Figure IMGAF001_ABST
Abstract
Description
Cross-reference to related applications
[0001] This patent application claims priority from Italian patent application no. 102024000027207 filed on December 2, 2024, the entire disclosure of which is incorporated herein by reference.Technical field
[0002] This invention relates to a double-walled flue system.Background
[0003] In general, a flue consists of several elements (tube sections and / or fittings) joined together.
[0004] In particular, double-walled flue elements are known having an inner wall and an outer wall separated by a gap.
[0005] For example, flue systems are known having elements with an inner wall made of polymer material, in particular polypropylene, an outer wall made of metal, in particular stainless steel, and an air gap (that is, the gap contains air).
[0006] The outer wall, being made of metal, has practically no insulating function and the overall insulation value of the system may not be fully satisfactory, depending on the type of application context. In addition, the use of metal parts increases the overall weight of the product.
[0007] Another drawback lies in the appearance of the metal wall, which is particularly significant if the flue is installed outside buildings or, in any case, with exposed sections, especially if it is located in prestigious, protected housing contexts or in historical centres. To achieve a certain colour, it is necessary to paint the metal surface, but this increases costs and processing time in the factory, as well as entailing the risk of the paint peeling off over time at the most stressed points, particularly near the chimney stack where acidic condensate can settle on the paint.
[0008] Alternatively, it is well known to make the outer wall of copper sheet: after oxidation, copper actually takes on a burnished colour, commonly known as "dark brown", and is particularly prized. However, copper is a very expensive material: in addition to the initial cost, the possibility that the product, once installed, may be stolen must be taken into account. In addition, the oxidation of copper takes a relatively long time, so that a certain amount of time must elapse before the copper takes on the desired colour, during which the aesthetic effect is not satisfactory.
[0009] An outer metal wall made of sheet metal can also have sharp and dangerous edges, which can cause cutting accidents to operators during assembly and, in any case, require great care.
[0010] Even in the event of an accidental fall of a flue element / component during installation, the metal is easily dented, especially at the edges, often rendering the piece unusable.
[0011] Clearly, all of the highlighted drawbacks are present, to an even greater extent, in systems, also known, with both inner and outer walls made of metal.
[0012] In known systems, then, double-walled elements are generally joined to each other by means of male / female coupling portions: both the inner and outer tube of each element are thus equipped with radially enlarged female portions (so-called cups) that receive respective male portions of another element. In known systems, the pressure seals are placed only on the inner tube, which has the various elements mounted with their respective cups in the watertight direction; the outer tube, on the other hand, usually has the respective male and female coupling portions oriented in the opposite direction to the inner tube and without gaskets. This means that in the event of any condensate leaking from the inner tube to the outside, the outer cups, since they are opposite the inner cups, encourage condensate to leak out onto the outside of the tubing, causing dripping onto the outside of the installed tubing.
[0013] The known systems therefore seem to have room for improvement, particularly with regard to the effectiveness of insulation and the ease of use, as well as the simplicity and speed of implementation and assembly.
[0014] One purpose of this invention is to provide a double-walled flue system that is free of the drawbacks of the prior art highlighted herein; in particular, one purpose of this invention is to provide a system that is extremely simple and inexpensive to make, simple and quick to use for making flues, while being fully effective in terms of thermal insulation, mechanical seal, and seal against fluids circulating in the flue.Summary
[0015] This invention therefore relates to a double-walled flue system as defined in essential terms in the appended claim 1.
[0016] Additional features of the invention are defined in the dependent claims.
[0017] The system of the invention, in addition to being particularly simple and inexpensive to implement, is quick and easy to use to assemble flues, and is fully effective in terms of thermal insulation, mechanical sealing, and fluid-tightness.
[0018] The system of the invention is particularly suitable for being mounted on the outside of buildings and exposed, having strong thermal insulation, superior to that of similar systems with an air gap between two metal walls or between a metal wall and a polymer wall; and being able to be equipped, right from the manufacturing stage without specific surface finishing operations, with a colour suitable for outdoor use, in particular a burnished-brown colour (dark brown, RAL 8019) that simulates that of copper oxidised over time.Brief description of the drawings
[0019] The invention is further described in the following non-limiting embodiments, with reference to the figures in the accompanying drawings in which: Figure 1 is an exploded perspective view of an element forming part of the double-walled flue system according to the invention; Figure 2 is a longitudinal cross-section view of the element in Figure 1; Figure 3 is a longitudinal cross-section view of a double-walled flue section made using the system of the invention; Figures 4A, 4B are two opposite perspective views of a component of the element in Figure 1, namely a locking ring; Figure 5 is a longitudinal cross-section view of a different embodiment of the element in Figure 1. Description of embodiments
[0020] With reference to Figures 1-3, a double-walled flue system 1 comprises multiple elements 2 that can be coupled together to form a flue.
[0021] Figures 1 and 2 show, as an example, a linear element 2 of the system 1; Figure 3 shows, again as an example, two linear elements 2 joined together. Clearly, the system 1 can comprise not only linear elements of various lengths and diameters but also curved elements, optionally having various angles of curvature, T-connection elements, inspection elements fitted with removable plugs, etc.
[0022] The element 2 extends along a longitudinal axis A between two opposite longitudinal ends 3, 4 and comprises an inner tube 5 and an outer tube 6, coaxial to each other.
[0023] The inner tube 5 and the outer tube 6 are radially spaced apart and separated by an air gap 7 (that is, an annular space delimited by the inner tube 5 and the outer tube 6 and filled with air and containing no thermal insulation material).
[0024] The inner tube 5 and the outer tube 6 have, at their axially opposite ends located at the ends 3, 4 of the element 2, respective radially enlarged female portions 11, 12 defined as connection cups, and respective male portions 13, 14, axially opposite the female portions 11, 12 and insertable into respective female portions 11, 12 of another element 2, as shown in Figure 3.
[0025] The female portions 11, 12 are joined to the respective male portions 13, 14 by respective restrictions 15, 16.
[0026] According to the invention, both the inner tube 5 and the outer tube 6 are made of polymer material, in particular polypropylene (PPs).
[0027] The female portions 11, 12 of the inner tube and the outer tube 6 are both located at the same longitudinal end 3 of the element 1.
[0028] The female portions 11, 12 of the inner tube 5 and the outer tube 6 are both provided with respective radial seal annular gaskets 21, 22, preferably made of elastomer material and housed in respective annular seats 23, 24 and projecting radially inside the respective female portions 11, 12 to cooperate with respective male portions 13, 14 of another element of the system (Figure 3). For example, the seats 23, 24 are formed in respective annular ridges 25, 26 that extend radially outwards from the female portions 11, 12.
[0029] The element 2 comprises a locking ring 30 arranged in the gap 7 for axially locking the inner tube 5 and the outer tube 6 with respect to each other, and radially coupled in a fluid-tight manner to the inner tube 5 and the outer tube 6.
[0030] Referring to Figures 3A, 3B as well, the locking ring 30 comprises a first sleeve 31, a second sleeve 32 and an intermediate radially outer flange 33 arranged axially between the sleeves 31, 32.
[0031] The sleeve 31 rests on the female portion 11 of the inner tube 5 and is spaced apart from the female portion 12 of the outer tube 6 by an annular space 34, so as to receive a male portion 13 of an outer tube 6 of another element 2 (Figure 3).
[0032] The sleeve 32 is coupled by radial interference to the male portions 13, 14 of the inner tube 5 and the outer tube 6.
[0033] In the embodiment illustrated (but not necessarily), the sleeve 32 has an inner side wall 35a and an outer side wall 35b, coaxial and radially spaced apart from each other and joined by longitudinal inner ribs 36a angularly spaced apart from each other; and a plurality of longitudinal outer ribs 36b, angularly spaced apart from each other and extending from an outer lateral surface 37 of the sleeve 32, for example arranged above respective ribs 36a. The inner side wall 35a is fitted to an outer lateral surface 38 of the inner tube 5, and the ribs 36b contact an inner lateral surface 39 of the outer tube 6 (Figure 2).
[0034] The flange 33 is arranged at an axial end of the sleeve 31, between one sleeve 31 and another sleeve 32, and is in contact against the restrictions 15, 16 which join the female portion 12 and the male portion 14 of the outer tube 6 and, respectively, the female portion 11 and the male portion 13 of the inner tube 6, preferably by means of their own inclined side surfaces having the same inclination as the restrictions 15, 16.
[0035] The locking ring 30 therefore has respective opposite sealing annular surfaces (for example, but not necessarily, located on the flange 33) contacting the outer lateral surface 38 of the inner tube 5 and the inner lateral surface 39 of the outer tube 6, respectively. When several elements 2 are joined together (as shown in Figure 3), the locking rings 30 of two consecutive elements 2 joined together delimit respective closed insulating cells containing still air.
[0036] Advantageously, the locking ring 30 consists of a monolithic piece, for example made of elastomer.
[0037] The element 2 also comprises at least one centring ring 40, preferably made of elastomer material, located in the gap 7 between the male portions 13, 14 and radially contacting the outer lateral surface 38 of the inner tube 5 and the inner lateral surface 39 of the outer tube 6.
[0038] For example, the centring ring 40 has a U-shaped cross-section and has two lips 43 that protrude from an annular disc 44 and are slightly inclined with respect to the axis A, so as to cooperate by interference with the outer lateral surface 38 of the inner tube 5 and with the inner lateral surface 39 of the outer tube 6.
[0039] The centring ring 40 preferably does not connect the inner tube 5 and the outer tube 6 in a fluid-tight manner but is provided with axially through openings (for example, small holes essentially parallel to the axis A) that are formed, for example, on the annular disc 44. These allow air to pass between respective axially opposite ends of the centring element 40, the main purpose of which is to allow air to escape during the assembly phase.
[0040] The outer tube 6 preferably has a thermal resistance of at least 0.0400 (m 2< K) / W at 60°C, preferably greater than or equal to 0.0495 (m 2< K) / W at 60°C.
[0041] The element 2, as a whole, has a thermal resistance of at least 0.0400 (m 2< K) / W at 60°C, preferably greater than or equal to 0.0495 (m 2< K) / W at 60°C.
[0042] According to one aspect of the invention, the outer tube 6 is made of a polymer material having the colour RAL 8019 (dark brown), so that it resembles the natural colour of oxidised copper.
[0043] In the embodiment illustrated in Figures 1-3, the inner tube 5 and the outer tube 6 have the same length and are arranged in such a way that their axial opposite ends are flush with each other; in other words, the inner tube 5 and the outer tube 6 do not protrude axially from each other.
[0044] In other embodiments, as shown for example in Figure 5, the inner tube 5 and the outer tube 6 are arranged axially offset.
[0045] In particular, the male portion 13 of the inner tube 5 protrudes axially beyond the male portion 14 of the outer tube 6, and the female portion 12 of the outer tube 6 protrudes axially beyond the female portion 11 of the inner tube 5.
[0046] Figure 5 also shows a variant of the locking ring 30, which still comprises a sleeve 31 and a radially outer flange 33 located at an axial end of the sleeve 31.
[0047] The sleeve 31 rests against the ridge 25 with its own free end edge, opposite the flange 33, so that the locking ring 30 is axially locked between the ridge 25 and the restriction 16.
[0048] For example, the sleeve 31 of the locking ring 30 comprises a cylindrical wall facing the inner lateral surface 36 of the female portion 12 of the outer tube 6 (from which it is separated by the annular space 34), and annular ribs extending from the cylindrical wall to contact the outer lateral surface 38 of the female portion 11 of the inner tube 5.
[0049] Lastly, it is clear that modifications may be made to the double-walled flue system described and illustrated herein, and variations produced thereto, without departing from the scope of this invention, as set forth in the attached claims.
Claims
1. A double-walled flue or chimney system (1), comprising a plurality of elements (2) which can be coupled to each other to form a flue or chimney; wherein each element (2) extends along an axis (A) between two longitudinal ends (3, 4) and comprises an inner tube (5) and an outer tube (6), radially spaced apart and separated by an air gap (7); and wherein the inner tube (5) and the outer tube (6) have, at respective axially opposite ends, respective radially enlarged female portions (11, 12) defining connection cups, and respective male portions (13, 14), axially opposite to the female portions (11, 12) and insertable in respective female portions (11, 12) of another element of the system; the female portions (11, 12) of the inner tube (5) and the outer tube (6) are both located at the same longitudinal end (3) of the element (2); the system being characterised in that the inner tube (5) and the outer tube (6) are both made of polymeric material, in particular polypropylene (PPs); and in that each element (2) comprises a locking ring (30) arranged in the gap (7) for axially locking the inner tube (5) and the outer tube (6) with respect to each other, and radially coupled in a fluid tight manner to the inner tube (5) and the outer tube (6) so that, when several elements (2) are joined together, the locking rings (30) of two consecutive, joined elements (2) delimit respective closed, insulated cells containing still air.
2. The system according to claim 1, wherein the inner tube (5) and the outer tube (6) are both made of polypropylene (PPs).
3. The system according to claim 1 or 2, wherein the locking ring (30) comprises a first sleeve (31), which rests on the female portion (11) of the inner tube (5) and is spaced from the female portion (12) of the outer tube (6) by an annular space (34), so as to receive a male portion (13) of an outer tube (6) of another element (2); a second sleeve (32) which is coupled with radial interference to the male portions (13, 14) of the inner tube (5) and the outer tube (6); and an intermediate radially outer flange (33) disposed between the sleeves (31, 32) and contacting against a restriction (16) joining the female portion (12) and the respective male portion (14) of the outer tube (6).
4. The system according to claim 3, wherein the second sleeve (32) has an inner side wall (35a) and an outer side wall (35b), coaxial and radially spaced from each other and joined by longitudinal inner ribs (36a) angularly spaced from each other; and a plurality of longitudinal outer ribs (36b), angularly spaced from each other and extending from a lateral surface (37) of the second sleeve (32).
5. The system according to any one of the preceding claims, wherein the female portions (11, 12) of the inner tube (5) and the outer tube (6) are both provided with respective radial seal annular gaskets (21, 22), housed in respective annular seats (23, 24) and projecting radially inside the respective female portions (11, 12) to cooperate with respective male portions (13, 14) of another element of the system.
6. The system according to any one of the preceding claims, comprising at least one centring ring (40) located in the gap (7) between the male portions (13, 14) and radially contacting an outer lateral surface (38) of the inner tube (5) and an inner lateral surface (39) of the outer tube (6).
7. The system according to claim 6, wherein the centring ring (40) has a U-shaped cross-section and has two lips (43) which protrude from an annular disc (44) and are slightly inclined with respect to the axis (A), so as to cooperate by interference with the outer lateral surface (38) of the inner tube (5) and with the inner lateral surface (39) of the outer tube (6).
8. The system according to any one of the preceding claims, wherein the outer tube (6) has a thermal resistance of at least 0.0400 (m2K) / W at 60°C, preferably greater than or equal to 0.0495 (m2K) / W at 60°C.
9. The system according to any one of the preceding claims, wherein the element (2) has a thermal resistance of at least 0.0400 (m2K) / W at 60°C, preferably greater than or equal to 0.0495 (m2K) / W at 60°C.
10. The system according to any one of the preceding claims, wherein the outer tube (6) is made of a polymeric material having the colour RAL 8019 (dark brown).