WO2019002164A1

WO2019002164A1 - Electric heating device, particularly for radiant panels, and electric heating cable including the device

Info

Publication number: WO2019002164A1
Application number: PCT/EP2018/066867
Authority: WO
Inventors: Camerra STEFANO; Camerra MATTEO; Camerra ELIA
Original assignee: Warmset Srl
Current assignee: Warmset Srl
Priority date: 2017-06-29
Filing date: 2018-06-25
Publication date: 2019-01-03
Anticipated expiration: 2019-12-29
Also published as: IT201700072808A1

Abstract

An electric heating device, particularly for radiant panels, which includes at least one substantially flexible resistive element arranged inside a substantially flexible insulating structure. The particularity of the present invention resides in that the insulating structure includes two first strips made of a thermoformable polymeric material, joined together so as to form a closed section; the insulating structure thus formed is adapted to pass from a substantially flattened shape to a substantially tubular shape upon exceeding a preset temperature threshold. The present invention also relates to an electric heating cable that incorporates the electric heating device and to a radiant panel equipped with the electric heating device or with the electric heating cable.

Description

ELECTRIC HEATING DEVICE, PARTICULARLY FOR RADIANT PANELS, AND ELECTRIC HEATING CABLE INCLUDING THE DEVICE

The present invention relates to an electric heating device, particularly for radiant panels, to an electric heating cable that includes the device, and to a radiant panel equipped with the electric heating device or with the electric heating cable.

In the field of electric heating, it is known that there are heating devices that have a substantially flat shape and are essentially constituted by resistive portions which are heated by Joule effect when current flows.

These electric heating devices can have structures with a different configuration which have low thickness as their main advantage.

A typical use of electric heating devices with a flattened shape occurs in the provision of radiant floors or walls, in which they are arranged respectively below the floor screed and the finishing plaster.

There is also another way of using these devices, which essentially consists in associating them with plate-like supports made of various materials in order to obtain electrically powered radiant panels.

WO2013091832 discloses an electric cable, particularly for heating systems, which has at least one substantially flat conductor arranged within a substantially flat insulating sheath. The conductor is essentially formed by a conducting ribbon joined to an insulating ribbon, and has one or more folding lines extending longitudinally so as to form flaps that are narrower than the two ribbons and are folded onto themselves so as to render the outer surface of the conductor an insulating surface.

Despite being advantageous in many respects (weight, space occupation, complexity and production cost, etc.), electric heating devices according to the prior art however have some drawbacks which have still not been solved.

In particular, a drawback of known electric heating devices in radiant panels of the type described above is that their flattened shape on the one hand indeed facilitates their insertion in the channels that pass through the panel but on the other hand leaves a void inside the channels that accommodate them.

The presence of empty space in the channels in which the electric heating devices are accommodated hinders or slows the diffusion of heat through the panel.

The aim of the invention is to solve the problems described above, providing an electric heating device, particularly for radiant panels, and an electric heating cable that includes the device, which are easy to be inserted in the radiant panels and at the same time are capable of maximizing their thermal efficiency.

Within the scope of this aim, a particular object of the invention is to provide an electric heating device and an electric heating cable that are capable of withstanding even prolonged immersions in water, being safe even for use in humid environments.

Another object of the invention is to provide an electric heating device and an electric heating cable that are particularly advantageous from the point of view of space occupation and weight.

Another object of the invention is to provide an electric heating device and an electric heating cable that are relatively simple from the point of view of the production process, with a reduction of production time and consequently of the related costs.

Another object of the invention is to provide a radiant panel that allows to combine in a single apparatus characteristics that are currently difficult to combine, such as excellent thermal efficiency, complete safety from an electrical standpoint and high capacity to withstand immersions in water.

This aim, as well as the objects mentioned and others which will become better apparent hereinafter, are achieved by an electric heating device, particularly for radiant panels, which includes at least one substantially flexible resistive element arranged inside a substantially flexible insulating structure; the electric heating device being characterized in that the insulating structure includes at least two first strips made of a thermoformable polymeric material, joined together so as to form a closed section; the insulating structure being adapted to pass from a substantially flattened shape to a substantially tubular shape upon exceeding a preset temperature threshold.

This aim, these objects and others which will become better apparent hereinafter are also achieved by an electric heating cable, particularly for radiant panels, characterized in that it includes a pair of electric heating devices according to the invention; the electric heating devices being arranged inside a composite sheath; the sheath including at least two second strips made of a thermoformable polymeric material which are mutually joined so as to form a closed section; the sheath being adapted to pass from a substantially flattened shape to a substantially tubular shape upon exceeding the preset temperature threshold.

This aim, these objects and others which will become better apparent hereinafter are also achieved by a radiant panel, which includes at least one honeycomb plate made of synthetic material, provided with a plurality of longitudinal channels; the longitudinal channels being extended between opposite ends of the honeycomb plate and being substantially mutually parallel; the radiant panel being characterized in that it includes an electric heating device according to the invention inserted in at least one part of the longitudinal channels, or an electric heating cable according to the invention inserted in at least one part of the longitudinal channels.

Further characteristics and advantages will become better apparent from the description of preferred but not exclusive embodiments of an electric heating device, of an electric heating cable and of a radiant panel according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a perspective view of an electric heating device according to the invention in a substantially flattened shape;

Figure 2 is a perspective view of an electric heating device according to the invention in a substantially tubular shape;

Figure 3 is a perspective view of an electric heating cable according to the invention in a substantially flattened shape;

Figure 4 is a perspective view of an electric heating cable according to the invention in a substantially tubular shape;

Figure 5 is a perspective view of a radiant panel according to the invention.

With reference to Figures 1 and 2, an electric heating device, particularly for radiant panels, generally designated by the reference numeral 1 , includes a substantially flexible resistive element 2, which is arranged within a substantially flexible insulating structure 3.

According to the present invention, the insulating structure 3 is formed by the joining of at least two first strips 4a and 4b made of a polymeric material that is thermoformable and impermeable to fluids, which allow it to pass from a substantially flattened shape, shown schematically in Figure 1 , to a substantially tubular shape, shown schematically in Figure 2, upon exceeding a predetermined temperature threshold.

In a preferred embodiment of the invention, this temperature threshold is between approximately 60°C and approximately 90°C.

Advantageously, the two first strips 4a and 4b are mutually joined so as to give the insulating structure 3 both longitudinal and transverse continuity.

More precisely, the first strips 4a and 4b are folded longitudinally onto themselves along folding lines which are designated respectively by the reference numerals 5a and 5b and are inserted at least partially inside each other axially.

In practice, the folding flaps of the first outermost strip, for example the flaps of the first strip 4a formed by the folding line 5a, are superimposed and joined permanently to the folding flaps of the first innermost strip, for example the flaps of the first strip 4b formed by the folding line 5b.

The folding lines 5a and 5b of the first strips 4a and 4b are arranged laterally, on mutually opposite sides, with respect to the longitudinal axis 50 of the insulating structure 3.

In a preferred embodiment, the first strips 4a and 4b are made of polyester film or polypropylene film constituted by one or more layers, which gives the insulating structure

3 both thermoformability and impermeability to fluids.

In this embodiment, the first strips 4a and 4b are mutually joined by means of adapted polyurethane glue, which is interposed between the corresponding folding flaps and is adapted to remain solid even when the temperature threshold that changes the shape of the insulating structure 3 is exceeded.

Preferably, the resistive element 2 is constituted by filaments 6 (or fibers) of carbon-containing material which are inserted within the first strip 4b, i.e., within the innermost first strip of the two that form the insulating structure 3.

However, it is evident that according to different embodiments of the invention which are not shown, the resistive element 2 might be provided in another manner which is compliant with the requirements without thereby altering the inventive concept underlying the invention.

For example, in a constructive variation which is not shown, the resistive element 2 is constituted by a lamina made of metallic material, such as aluminum or copper, which is made to adhere to the internal surface of the first strip 4b, i.e., of the innermost first strip.

According to another aspect of the invention, an electric heating cable, particularly for radiant panels, is provided which is shown schematically in Figures 3 and 4, where it is designated generally by the reference numeral 100.

The electric heating cable 100 includes a pair of electric heating devices 101 accommodated within a composite sheath 103.

The electric heating devices 101 are substantially equivalent to the electric heating device 1 already described previously and therefore will not be described further in order to not encumber the present description.

According to the invention, the sheath 103 is formed by the joining of at least two second strips 104a and 104b, made of a thermoformable polymeric material which is also impermeable to fluids, which allow it to pass from a substantially flattened shape, shown schematically in Figure 3, to a substantially tubular shape, shown schematically in Figure 4, upon exceeding the temperature threshold already mentioned earlier.

Advantageously, the two second strips 104a and 104b are mutually joined so as to give the sheath 103 both longitudinal and transverse continuity.

More precisely, the second strips 104a and 104b are folded longitudinally onto themselves along folding lines which are designated respectively by the reference numerals 105a and 105b, and are inserted at least partially inside each other axially.

In practice, the folding flaps of the second outermost strip, for example the flaps of the second strip 104a which are formed by the folding line 105a, are superimposed and joined permanently to the folding flaps of the second innermost strip, for example the flaps of the second strip 104b formed by the folding line 105b.

The folding lines 105a and 105b of the second strips 104a and 104b are arranged laterally, on mutually opposite sides, with respect to the longitudinal axis 150 of the shape of the sheath 103.

In a preferred embodiment, the second strips 104a and 104b are made of a polyester film or polypropylene film constituted by one or more layers, which gives the sheath 103 both thermoformability and impermeability to fluids.

In this embodiment, the second strips 104a and 104b are mutually joined by means of adapted polyurethane glue, which is interposed between the corresponding folding flaps and is adapted to remain solid even when the temperature threshold that modifies the shape of the sheath 103 is exceeded.

Preferably, in the second strip 104b, i.e., in the innermost second strip, the polyester film or polypropylene film is coupled to a film of ductile metal 106, for example aluminum, which acts as a ground conductor.

Advantageously, the electric heating cable 100 also includes a protective cladding 1 10 which is interposed between the sheath 103 and the electric heating devices 101.

More precisely, the protective cladding 1 10 is formed by a pair of third strips 1 1 1 a and 1 1 1 b made of a thermoformable polymeric material, which are superimposed and made to adhere to the outer surfaces of the electric heating devices 101 , so as to form a sandwich-like structure.

In a preferred embodiment, the third strips 1 1 1 a and 11 1 b are made of a film or nonwoven fabric made of polyester or polypropylene, constituted by one or more layers, which gives the protective cladding 110 the capability to undergo thermoforming.

In this embodiment, the third strips 1 1 1 a and 1 11 b are made to adhere to the outer surfaces of the electric heating devices 101 by means of an adapted self-adhesive glue, which is adapted to assume a fluid consistency when the temperature threshold that thermoforms the protective cladding 1 10 is exceeded.

In other words, when the temperature threshold is exceeded, the third strips 1 1 1 a and 1 1 1 be come unstuck from the outer surfaces of the electric heating devices 101.

Conveniently, the protective cladding 1 10 is joined to the second strip 104b, or to the innermost second strip, only at its larger sides, so as to define a longitudinal central strip which lacks glue between the ductile metal film 106 and the outer walls of the protective cladding 110, as shown in Figure 3, in which the region without glue is located between the two central dashed lines.

This facilitates considerably sheath stripping during wiring; in fact in this manner, by removing a portion of electric heating cable 100 related to the larger sides of the sheath 103 it is possible to create on each face a tab in which the ductile metal film 106 can be connected easily to the ground; at the same time, the two electric heating devices 101 are made accessible.

According to a further aspect of the invention, a radiant panel is described which is shown schematically in Figure 5, where it is designated generally by the reference numeral 1000.

The radiant panel 1000 is constituted by a honeycomb plate 1001 made of synthetic material, such as polycarbonate, polymethyl methacrylate (better known by the commercial name Plexiglas®), or polypropylene, provided with a series of longitudinal channels 1002 which are mutually parallel and superimposed and are extended between opposite ends thereof.

According to the invention, the radiant panel 1000 includes an electric heating device 1 or an electric heating cable 100, which is inserted during construction in at least one part of the longitudinal channels 1002.

The electric heating device 1 and the electric heating cable 100 described above are substantially equivalent to the ones already described previously and therefore are not described further.

Advantageously, each longitudinal channel 1002 has a width that is greater than or equal to the width of the electric heating device 1 or of the electric heating cable 100 and a height that is greater than or equal to the thickness of the latter.

This allows to insert the electric heating device 1 or the electric heating cable 100 within part of the longitudinal channels 1002 substantially without making any modification to the honeycomb plate 1001.

In a preferred embodiment, the electric heating device 1 or the electric heating cable 100 is inserted in the longitudinal channels 1002 with a zigzag pattern, i.e., following trajectories which are extended in opposite directions.

In this embodiment, the electric heating device 1 or the electric heating cable 100 is folded onto itself proximate to the lateral ends of the honeycomb plate 1001 so as to define a winding path formed by parallel outgoing and return segments, which coincide with a part of the longitudinal channels 1002.

In the specific case of the radiant panel 1000 shown, for example, these parallel segments are substantially coplanar and uniformly mutually spaced.

More precisely, in the radiant panel 1000 the longitudinal channels 1002 that accommodate the electric heating device 1 or the electric heating cable 100 are alternated with at least one empty longitudinal channel 1002.

However, it is evident to the person skilled in the art that in some constructive variations not shown the electric heating device 1 or the electric heating cable 100 might also be arranged differently without thereby abandoning the scope of the adopted solution idea.

Advantageously, the folded portions of the electric heating device 1 or of the electric heating cable 100 can be accommodated in adapted millings, which are not shown in the accompanying figures, provided at the opposite ends of the honeycomb plate 1001 and subsequently sealed with adapted finishing profiles.

The operation of the electric heating device 1 and of the electric heating cable 00 according to the invention is evident from what has been described above.

In particular, as regards the electric heating device 1 , it is pointed out that when the resistive element 2 is crossed by current its heating due to the Joule effect begins.

The temperature increase of the resistive element 2 leads to the heating of the fluid, typically air, that is contained in the insulating structure 3 (even though it is flat) and leads to its consequent increase in volume.

This leads first of all to a heating of the insulating structure 3 and then to a plastic deformation thereof, as a consequence of the expansion of the heated fluid.

The deformation of the insulating structure 3 continues until it assumes a substantially tubular shape.

It is pointed out that the deformation is possible both by virtue of the thermoformability of the material of which the insulating structure 3 is made and by virtue of the impermeability to fluids of the material, which is capable of retaining inside the insulating structure 3 the fluid heated by the temperature increase of the resistive element 2.

The impermeability to fluids, however, also has an important role in terms of safety, since it allows the electric heating device 1 to withstand even prolonged immersions in water.

The capability of the insulating structure 3 to undergo deformation until it assumes a substantially tubular shape becomes particularly important when the electric heating device 1 is inserted in the longitudinal channels 1002 that are extended between opposite ends of a radiant panel 1000 having a honeycomb structure.

In fact, in this case the expansion of the insulating structure 3 causes the electric heating device 1 to make contact substantially with the entire internal surface of the longitudinal channel 1002 in which it is inserted, with optimum heat transmission, which maximizes the radiation of the radiant panel 1000.

Substantially similar remarks apply in the case of the electric heating cable 100. However, in this case the heating of the electric heating devices 101 not only causes the thermoforming of the related insulating structures but also causes the deformation of the protective cladding 1 10 and of the sheath 103.

As regards in particular the protective cladding 110, it is noted that the temperature increase causes not only its deformation but also the ungluing of the electric heating devices 101 by virtue of the characteristics of the glue that is used.

Evidently, the capability of the electric heating cable 100 to undergo deformation until it assumes a substantially tubular shape becomes particularly important when it is inserted in the longitudinal channels 1002 of a radiant panel 1000 that is substantially equivalent to the one that has already been described.

In this case also, the expansion of the electric heating cable 100 leads to substantially complete contact with the internal surface of the longitudinal channel 1002 in which it is inserted, with optimum heat transmission which maximizes the radiation of the radiant panel 1000. In practice it has been found that the electric heating device, particularly for radiant panels, and the electric heating cable that includes the device, according to the invention, fully achieve the intended aim, since by virtue of their initially flat structure they are easy to insert in the radiant panels; also, by subsequently modifying their shape with heat, to the point of touching the internal walls of the channels in which they are inserted, they are capable of maximizing the thermal efficiency of the panels.

The electric heating device and the electric heating cable according to the invention are also capable of withstanding prolonged immersions in water, thus being safe also for use in humid environments.

The electric heating device and the electric heating cable according to the invention are advantageous from the point of view of space occupation and weight, facilitating also all the logistic operations linked to their marketing.

The electric heating device and the electric heating cable according to the invention are relatively simple from the point of view of the production process, with an evident reduction of production time, being advantageous also from a purely economic standpoint.

It is also noted that the electric heating device and the electric heating cable according to the invention allow to provide a radiant panel that has an excellent thermal efficiency, is totally safe from an electrical standpoint and is capable of withstanding even prolonged immersions in water.

The electric heating device, particularly for radiant panels, the electric heating cable that includes the device and the radiant panel equipped with the electric heating device or with the electric heating cable are susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may be replaced with other technically equivalent elements.

The materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may of course vary according to the requirements and the state of the art.

This application claims the priority of Italian Patent Application No.102017000072808, filed on June 29, 2017, the subject matter of which is incorporated herein by reference.

Claims

1. An electric heating device, particularly for radiant panels, comprising at least one flexible resistive element (2) arranged inside a flexible insulating structure (3); said electric heating device (1 ) being characterized in that said insulating structure (3) comprises at least two first strips (4a, 4b) made of a thermoformable polymeric material, joined together so as to form a closed section; said insulating structure (3) being adapted to pass from a flattened shape to a tubular shape upon exceeding a preset temperature threshold.

2. The electric heating device according to the preceding claim, characterized in that said first strips (4a, 4b) are folded longitudinally and are at least partially inserted axially inside each other; the longitudinal folding lines (5a, 5b) of said first strips (4a, 4b) being arranged laterally, at mutually opposite sides, with respect to the longitudinal axis (50) of said insulating structure (3).

3. The electric heating device according to one or more of the preceding claims, characterized in that said first strips (4a, 4b) are made of polyester film, or polypropylene film, having one or more layers; said first strips (4a, 4b) being joined together by means of polyurethane glue adapted to remain solid even upon exceeding said preset temperature threshold.

4. The electric heating device according to one or more of the preceding claims, characterized in that said preset temperature threshold is comprised between about

60°C and about 90°C.

5. The electric heating device according to one or more of the preceding claims, characterized in that said resistive element (2) comprises a plurality of filaments (6) of carbon-containing material; said filaments (6) being inserted inside the innermost of said first strips (4b).

6. The electric heating device according to one or more of the preceding claims, characterized in that said resistive element (2) comprises a foil made of metallic material; said foil being associated with the innermost of said first strips (4b).

7. An electric heating cable, particularly for radiant panels, characterized in that it comprises a pair of electric heating devices (101) according to one or more of the preceding claims; said electric heating devices (101) being arranged inside a composite sheath (103); said sheath (103) comprising at least two second strips (104a, 104b) made of a thermoformable polymeric material, joined together so as to form a closed section; said sheath (103) being adapted to pass from a flattened shape to a tubular shape upon exceeding said preset temperature threshold.

8. The electric heating cable according to one or more of the preceding claims, characterized in that said second strips (104a, 104b) are folded longitudinally and are at least partially inserted axially inside each other; the longitudinal folding lines (105a, 105b) of said second strips (104a, 104b) being arranged laterally, on mutually opposite sides, with respect to the longitudinal axis (150) of said cable.

9. The electric heating cable according to one or more of the preceding claims, characterized in that said second strips (104a, 104b) are made of polyester film or polypropylene film having one or more layers; said second strips (104a, 104b) being joined together by means of polyurethane glue adapted to remain solid even upon exceeding said preset temperature threshold.

10. The electric heating cable according to one or more of the preceding claims, characterized in that at least one of said second strips (104b) comprises a film of metallic material (106) coupled to said polyester film or polypropylene film.

11. The electric heating cable according to one or more of the preceding claims, characterized in that it comprises a protective cladding (1 10) that is interposed between said sheath (103) and said electric heating devices (101 ); such protective cladding (1 10) being formed by at least two third strips (1 1 1 a, 1 11 b) made of a thermoformable polymeric material, which are superimposed and made to adhere to the outer surfaces of said electric heating devices in order to form a sandwich-like structure.

12. The electric heating cable according to one or more of the preceding claims, characterized in that said third strips (11 1 a, 1 1 1 b) are made of a film or nonwoven fabric of polyester or polypropylene having one or more layers; said third strips (1 11 a, 1 1 1 b) being joined to said electric heating devices (101) by means of self-adhesive glue adapted to acquire a fluid consistency upon exceeding said preset temperature threshold.

13. The electric heating cable according to one or more of the preceding claims, characterized in that said sheath (103) and said insulating structures are made of a polymeric material that is impermeable to fluids.

14. A radiant panel, according to either claims 1-6 and 7-13, comprising at least one honeycomb plate (1001 ) made of synthetic material, provided with a plurality of longitudinal channels (1002); said longitudinal channels (1002) extending between opposite ends of said honeycomb plate (1001) and being parallel to each other; said radiant panel (1000) being characterized in that it comprises an electric heating device (1 ) inserted in at least some of said longitudinal channels (1002), or an electric heating cable (100) inserted in at least some of said longitudinal channels (1002).