DESCRIPTION

Field of application

The present invention is generally applied to the technical sector related to furniture and, in particular, the present invention is about the designing and development of heating groups for electrically heated rooms.

In details, the present invention is related to the designing and development of heating groups which heat rooms by radiation.

State of the art

The use of heating groups for rooms with laminar bodies has been known in the art.

These groups, in particular, have electrically conductive portions and these portions are used as electrothermal transducers: the electrical power with which these portions are supplied is converted, due to their electrical resistivity, into heat, that is distributed to the surrounding room by radiation.

An example of this is described in the patent number FR 2 817 947, where is described an electrothermal transducer placed between a glass layer and a sheet-like aluminum element.

Heating groups completely made of glass are also known. They are usually made up of two glass multi-layered bodies. Between them, there is a sheet which is specifically modified to become a conductor so that an electric current that flow through it generates heat. The other sheet covers the first and is directed outwards. In this sense, it is electrically insulating and thermically conductive to radiate heat into the room and, at the same time, to electrically secure the heating group.

Since the group is extremely thin, this solution has the advantage of having a good performance and of occupying little space in the rooms in which it is used. This solution is applied to the rooms' perimeter walls just like the normal radiators and the like. The aforementioned group can be transparent, since it is made of glass and, consequently, it does not have a great visual impact or, alternatively, it can be decorated.

In any case, regardless the material used to build the heating group just described, such a heating group has the drawback that the heat radiated by the electrothermal transducer is radiated on both sides of the heating groups, that is the side towards the room to be heated and the side towards the rear part of the heating group. If there is a wall or an area which do not need to be heated, the radiated heat in this direction is considered partially lost because of heat dispersion through the wall next to another room or outwards. Besides this, the capacity to radiate and, as a consequence, to provoque flow of thermal energy in both directions brings about a major cooling of the group and, so, it is necessary to consume more electricity in order to keep the heating group at the set work temperature. This translates into the fact that heating costs are not optimized. Nowadays there is high awareness about energy costs and energy saving is an important issue so, in this context, the highlighted drawback is even more relevant.

The drawback of non-optimized energy consumption by the heating groups described above is evident also if other characteristics are taken into consideration.

The emitted heat is strictly related to the type of transducer, to its dimensions (a transducer exploits the electrical resistance and, as a consequence, the heat generated directly depends on the length of the path covered by electrical power) and to the regulation of the power source. The most important among these parameters is, obviously, the type of transducer; a parameter which is difficult to control in the known prior art.

The document EP 1 519 631 is also known. It describes a heated glass multi-layer body provided with an intermediate heating layer and a reflecting intermediate layer; the reflecting intermediate layer lies between the heating layer and the rear side of the heated layer so that the radiations emitted from the heating layer are totally reflected by the reflecting layer. However, the proposed solution is not an heating device and it also does not take into consideration that the layers of the multi-layer body are all heated by thermal conduction. In particular, heat transmission by radiation is the same in both directions of the glass, that is on the front side and on the rear side of the heated glass multi-layer body, because its external areas are not made of coated tempered glass. In other words, as the radiation is function of emissivity values of the external surfaces of the glass body, in the case just described in EP 1 519 631, since both of these surfaces are not made of coated tempered glass, both of them radiate heat without any difference between one surface and the other one. As a consequence, there is heat dispersion towards the rear side of the glass component, namely in an undesired direction.

Besides this, it is evident that the above-mentioned heat dispersion has the disadvantage that, if the glass component is used as a wall-mount heating system, more electric power is needed to keep it at the required work temperature.

Presentation of the invention

Scope of this invention is to at least partially overcome the drawbacks mentioned above by making available an electrically powered heating group that emits heat by radiation and that is essentially made up of sheet-like elements.

Another scope is to optimize, during the working phase, the power consumption and to build a heating group that generate an heat quantity that is optimized to reach the real needs.

A particular scope of the invention, within the general scope just mentioned, is that the heating group radiates heat mainly towards the room and not in other directions.

An additional scope is that, with the same powering consumption, the heating group have an higher surface temperature than the equivalent known groups. In other words, a scope of the invention is that the heating group shows a better performance compared with equivalent known groups and that, to keep the group at the work temperature, less electric power is needed compared with the equivalent known groups.

Another scope is that the heating group can be fully made of glass. Thus, another scope is that the heating group could be used as a piece of furniture.

These previous scopes, and additional ones that will be further described hereinafter, are reached by a heating group for rooms compliant with the claims later mentioned that must be considered as an integral part of this description.

In particular, the heating group consists in a series of sheet-like elements being disposed overlapped. In particular, there is one first sheet-like element, one second sheet-like element and, interposed, there is one third sheet-like element.

Besides this, stratification elements are interposed between the sheet-like elements in order to unite them to form an essentially full multi-layer body.

According to a characteristic of the invention, the first sheet-like element is directed towards the room to be heated, while the third sheet-like element comprises one electrothermal transducer connected to a power source to emit heat and to entirely heat the heating group.

According to another characteristic of the invention, the second sheet-like element is the most external sheet-like element and it is located at the rear of the heating group. Besides this, the second sheet-like element has an external surface having a decreased emissivity value and, in this way, it constitutes a reflecting shield at- the rear so that the majority of the heat generated is diffused by radiation from the first sheet-like element.

In other words, unlike the known prior art, the heating group of the invention has the posterior external surface treated in such a way that it has a decreased emissivity value to prevent radiating heat from it in an undesired direction.

From these considerations emerges that a heating group with these characteristics can distinguish itself for the fact that it occupies little space, in particular as concerns depth.

Furthermore, the heating group allows the rationalization of power consumption, since the majority of the heat produced can be radiated towards the room, thanks to the fact that the external surface of the second sheet-like element is thermally insulating and reflects the infrared.

In particular, installing a reflecting shield on the posterior external surface of the heating group allows to reflect the heat ^' diffused by thermal conduction throughout all the layers of the heating group. In this way the heat radiation in undesired directions is reduced to the minimum.

As a consequence, the electric consumption to keep the heating group of the invention at the work temperature to heat the room has profitably diminished. Related to this, the electric consumption to keep the heating group of the invention at the work temperature has diminished too, since heat dispersions in undesired directions have been reduced to the minimum.

Typically, but not necessarily, the sheet- like elements can be made , by glass or by other generally transparent equivalent materials.

Brief description of the drawings

Further features and advantages of the invention will become more apparent from the detailed description of a preferred, non exclusive embodiment of an heating group according to the invention presented by way of illustrating and non-limiting examples in connection with the accompanying drawing in which:

FIG. 1 shows an heating group for rooms according to the invention in an axonometric view;

FIG. 2 shows an exploded view of the heating group for rooms showed in FIG. 1;

FIG. 3 shows a detail of the heating group for rooms showed in FIG. 1.

Detailed description of some preferred embodiments

With reference to the cited figures, and particularly to the figures 1 and 2, an electrically powered heating group 1 for rooms is described.

This heating group 1 is constituted by a multi-layer body 2 comprising a plurality of sheet-like elements 3 being disposed overlapped each other by the interposition of stratification elements 4.

In the described embodiment, the sheet-like elements 3 are glass sheets forming a full multilayer body 2. Obviously, the use of transparent materials allows to produce heating groups that can be used in several contexts compared with opaque materials. In fact, it is noticed that, if a decorative heating group is needed, glass can be decorated by methods of digital printing suitable for heating groups that can be a quality piece of furniture and that can allow to freely choose the desired level of transparency, translucency and opacity.

Using glass, the overlapping is performed by interposing, between the glass sheets, materials such as polyvinyl butyral, ionomers like Sentry Glas Plus (SGP, Dupont), ethylene vinyl acetate (EVA) self-hardening adhesive films. The materials just listed are non-limiting examples for different embodiments of the invention using different materials.

From the figures it is noticed that the multi-layers body 2 comprises three sheet-like elements 3. This case too is a non- limiting example for different embodiments with more than three sheetlike elements.

In particular, there is one first sheet-like element 5 directed towards the room to be heated and from which the produced heat is radiated.

Then, there is one second sheet-like element 6, separated from the first sheet-like element 5 by way of a third sheet-like element 11 comprising an electrothermal transducer 15 which generates heat. Previously it was said that, according to the non-limiting embodiment being described, the sheet-like elements 3 are made of glass. In light of this, the third sheet-like element 11 is made of coated tempered glass or similar. The electrothermal transducer 15 comprises one first coating film (made by metal oxides) applied on a first surface 16 of the third sheet-like element 11. This coating makes the first surface 16 electrically conductive and characterized by such coefficient of resistance which transforms electric power into heat.

Obviously this is a non-limiting embodiment of the invention; in fact, for example, the third sheet-like element can be only partially coated with metal oxides, the coating with metal oxides can be carried out on the other surface of the third sheet-like element or the electrothermal transducer can be differently manufactured.

Furthermore, the multi-layer body of the invention can comprises more than one third sheetlike elements without trespassing the scope of the present invention. In this case, it is possible to precisely regulate the heat emitted by selecting how many transducers are powered and the level of supplied power. The consequence is a rationalisation of electric consumptions and a better compliance of the generated heat with the real needs.

In this sense, the heating group 1 of the invention conveniently comprises, even though it is not represented in the figures, an electric system to control and regulate the power supply of the electrothermal transducer 15.

According to an aspect of the invention, this control and regulating electric system typically comprises a microcontroller, a temperature sensor and a triggering system based on TRIAC devices (already known) to regulate the temperature of the heating group and the powering used.

In particular, if the heating group 1 might reach potentially dangerous temperatures, the control system reacts by interrupting the powering.

The triggering by TRIAC device is made by checking the phase angle of the power in order to manage both real power and reactive power. In this way it is possible to check power peaks so that the security of the heating group .1 of the invention is improved.

The same regulating group vantageously allows to regulate the heat emitted by the heating group, optimising, in this way, the power consumption and producing the necessary heat.

To summarize, the heat emitted by the heating group 1 of the invention can be regulated in different ways depending on the number of electrothermal transducers, on the type of electrothermal transducers and on the dimensions of the group itself.

During the manufacturing process of the heating group, therefore, in order to satisfy all the needs, it is important to choose the most suitable dimension for the heating group 1, but it is also possible to choose the number of electrothermal transducers 15 (and, so, of third sheet-like elements 11), and the type of each electrothermal transducer 15. In order to control more precisely the heat emitted by the heating group 1 and in order to adapt it to the most specific needs, the first surface 16 of the third sheet-like element 11 shows, as observed in fig. 3, a microfracture 18. This microfracture breaks the superficial coating made through metal oxides and, as a consequence, it is an electrically insulating element. This microfracture 18, as a consequence, allows to direct the path of the powering between the power poles of the first surface 16 and, in doing so, the electric resistance performed by the electrothermal transducer 15 can be modified. During the working of the heating group 1 it is possible, then, to made one or more microfractures 18 in order to vary the resistance value of the electrothermal transducer 15 without having to change the coating and remaining, therefore, in an optimal range for the proper functioning of TRIAC devices.

This expedient brings about additional advantages. The power supply of the eletrothermal transducer 15 occurs through two poles 19 which are connected to the first surface 16 on both sides so that power flows along the length of the path so defined. Making microfractures 18 allows to perform optimal paths so as the poles 19 can be arranged one next to the other. In doing so there are not cables, screenprinted conductive pathways or electric connections going from one point to the other of the heating group 1.

All this and, in particular, the above-mentioned embodiments, are possible due to the presence of the second sheet-like element 6 which constitutes a security element for the users. In fact, if the third sheet-like element 11 would be positioned as externally as possible, the power flowing on it would be dangerous for the users.

The heat generated from the transducer 15 is diffused on all the sheet-like elements 3 that constitute the multi-layer body 2. Once the first sheet-like element 5 is reached, the heat is radiated outwards to heat the room. The first sheet-like element is made by tempered float glass type. Therefore, it is electrically insulating in order to secure the transducer 15. Since it is directed outwards, the first sheet-like elements 5 is made mechanically resistant in an appropriate way. It is also thermally conductive and it has, on the external surface, a typically very high emissivity value, for example equal to 0,92, in order to foster radiation (which is the scope of the heating group 1).

That same heat, however, gets to the second sheet-like element 6 too, through this second sheet-like element 6 it would be radiated towards the rear side of the heating group 1. In this position, typically, there is a wall or, at least, a support whose heating is useless. In other words, as highlighted before, the heat radiated towards the rear side of the heating group 1 from the external surface 8 of the second sheet-like element 6 would be lost and the overall performance of the heating group 1 would worsen.

According to an aspect of the invention, therefore, the second sheet-like element 6 have a thermally insulating portion so that the heat generated by the third sheet-like element 11 is principally diffused by radiation through the first sheet-like element 5, limiting, in this way, heat dispersion in unwanted directions.

In particular, according to an aspect of the invention, the second sheet-like element 6 is made of tempered float glass or similar with its external surface 8 (that is towards undesired directions) coated with metal oxides. Metal oxides create, without affecting the transparency of the second sheet-like element 6, a shield reflecting the infrared, i.e. a shield stopping heat radiation in this direction and reflecting it towards the first sheet-like element 5. The external surface 8, in fact, with this coating film has a decreased emissivity values, for example below 0,14.

Therefore, the advantage is to put a limit on heat dispersion in unwanted directions and the consequence is a considerable increase in the performance of the heating group 1 of the invention.

In particular, it is observed that the position of the second sheet-like element 6 is not randomly defined, but it corresponds to the position of the most external layer of the multi-layer body 2 towards the rear side of the heating group 1. In this way, unlike the known prior art, the external surface 8 of the second sheet-like element 6 does not reflect only the heat radiated towards the rear side of the heating group 1 from the third sheet-like element 11, but also the heat radiated in the same direction from all the other sheet-like elements 3. They, in fact, are heated by thermal conduction and, therefore, they emit heat too. As concerns the invention, on the other hand, the external surface 8 has a low emissivity value and this allows the radiated heat to be for the most part reflected. Besides this, it is observed that the same second sheet-like element 6 heats up, but the heat radiated by this second sheet-like element is, in any case, reflected by the surface 8 towards the first sheet-like element 5.

The consequence is that the heating group 1 of the invention maximizes its thermal performance due to reflecting surface 8.

It is also clear that the coating of the external surface 8 increases the thermal resistance between the heating group 1 and the rear zone of the same. If there is a wall or a support device, the increase in thermal resistance allows the decrease of thermal flow in both directions and it also allows to keep the temperature of the heating group 1 higher with the same powering.

From all this derives that there is a decrease in the power required to take the heating group 1 of the invention to the work temperature and to keep the heating group 1 at this temperature.

In particular, the trials carried put show that the presence of the above-mentioned shield in said specific position allows to greatly improve the efficiency of the heating group 1, because the power consumption per hour diminishes by 20%.

The coating with metal oxides of the surface 8 of the second sheet-like element 6 makes this surface 8 electrically conductive. In this sense, currents induced by the electromagnetic field generated by the electrothermal transducer 15 develop on the surface 8. Therefore, the surface 8 is conveniently provided with an electrical connection to the ground to discharge the induced currents.

According to an additional aspect of the invention, on the internal surface 10 of the first sheetlike element 5 is applied (typically, but not necessarily through nanotechnology screen printing techniques directly applied on glass) a decoration that allows to improve the aestethic aspect of the heating group 1 without affecting its efficiency.

In the light of the foregoing, it is understood that the heating group of the invention overcomes the drawbacks of the prior art and reaches all the listed scope.

In particular, the heating group is peculiarly compact and thin and occupies, therefore, a very little space.

Nonetheless, it presents an optimized performance being reduced the power consumptions for the heating due to the thermal insulation on a portion of the second sheet-like element which corresponds to the most external layer on the rear side of the heating group of the invention.

The optimization is performed, also, due to the expedients applied to make heat generation as much adjustable as possible.

The heating group of the invention is suitable for several changes and variations and all of them are within the scope of the invention concept expressed in the claims herein. All the components can be replaced by other technically equal elements and different materials can be used, depending on the contingent needs, without exceeding the scope of the invention.

Even though the heating group of the invention has been described with reference to the figures, in the description and in the claims reference numbers are used in order to improve the understanding of the invention, but they do not constitute a limit to the claimed scope of protection.