Radiant glazing unit

The present invention relates to a radiant glazing unit particularly suitable for heating enclosed spaces, rooms, vehicle cabins, et cetera, where heating occurs by irradiation.

An enclosed space is usually heated by means of normal radiators using air convection, by means of underfloor piping, by means of ventilated hot air, et cetera.

All these kinds of system force structural and architectural constraints that often are poorly suited for modern architectures.

In particular in enclosed spaces that have large glazed areas, provided by means of structural glazing, it is not easy to place scarcely invasive or constraining heating modules.

Very often, this entails the choice of providing conventional heating systems designed to heat the entire volume of the ambient air, with considerable consumption and low yield.

This situation becomes increasingly negative as the clearances of the enclosed spaces increase, as in public enclosed spaces or offices.

The same situation occurs in any case in small enclosed spaces, such as the cabin of a vehicle.

The aim of the present invention is to provide a heating element that solves or reduces the problems of heating enclosed spaces.

Within this aim, an object of the invention is to use an existing component of the enclosed space to provide a heating element.

Another object is to provide a heating element that optimizes the yield of the absorbed energy.

Another object is to provide a heating element that does not require particular structural interventions in the enclosed space where it is to be installed, particularly if installation occurs after the construction of the enclosed space or building.

Another object is to provide a heating element that is easy to manufacture, install and operate.

This aim and these and other objects that will become better apparent hereinafter are achieved by a radiant glazing unit, of the type that comprises two glass panes, between which a heating means is interposed, characterized in that a multilayer assembly is arranged between said two glass panes and is composed of a sheet of clear plastic material that supports a sandwich, which in turn is composed of two outer films made of semiconducting material that contain a central layer of electrically conducting metallic material of variable thickness, which constitutes a large electrical resistor; a sheet made of a material that reflects infrared radiation, layers for connecting and monolithically coupling the various components of the assembly, and means for the controlled supply of electric power to the layer of metallic material being further provided.

Further characteristics and advantages of the invention will become better apparent from the following detailed description of a preferred but nonlimitative embodiment thereof, given by way of example and illustrated with the aid of the accompanying drawings, wherein: <ul id="ul0001" list-style="none" compact="compact"><li>Figure 1 is an exemplifying perspective view of a radiant glazing unit in front of which a person is placed;</li><li>Figure 2 is a view of the same situation as in Figure 1, with a chart that plots the amount of radiation emitted by the glazing unit;</li><li>Figure 3 is a partial perspective view of a glazing unit according to the invention, illustrating within its thickness the arrangement of the layers of the materials that compose it;</li><li>Figure 4 is an exploded view of the various layers that compose the glazing unit;</li><li>Figure 5 is a schematic view of the system for supplying electric power to the electrically conducting layer of the glazing unit;</li><li>Figure 6 is a schematic view of a particular embodiment of the glazing unit according to the invention;</li><li>Figure 7 is a schematic view of another particular embodiment of the glazing unit according to the invention;</li><li>Figure 8 is a perspective view of a test chamber with walls constituted by glazing units according to the invention.</li></ul>

With reference to the figures, the reference numeral 10 generally designates a glazing unit according to the invention.

The glazing unit 10, as shown in Figures 1-5, can be a structural glazing unit, i.e. a glazing unit that forms the outside wall of a building.

Likewise, the glazing unit 10 can be the pane of a window or of a door or in any case of a structure that delimits an enclosed space when said structure is required to be also transparent or in any case not opaque to light.

In a manner that is equivalent to what has been described above, the glazing unit 10 can also be non-flat, such as for example a vehicle windshield or window.

In the illustrated case, the glazing unit 10 comprises two ends 11 and 12 that are horizontal; the first end is horizontal because it is adjacent to a floor 13 of an enclosed space 14 and the second end is horizontal because it is adjacent to a ceiling 15; the glazing unit 10 is also delimited by two vertical sides 16 and 17.

In the illustrated case, the glazing unit 10 further comprises a containment and support frame 18.

The outline of a person 19 is placed in the enclosed space 14 in Figures 1 and 2 in order to describe the thermal effect of the glazing unit 10.

The glazing unit 10 is constituted, as shown more clearly in Figures 3 and 4, by two glass panes 20 and 21, whose thickness is chosen according to the overall dimensions of the glazing unit 10, and between which a multilayer assembly 22 is interposed.

In the illustrated case, the pane 20 faces the enclosed space 14, while the pane 21 is arranged outward.

The multilayer assembly 22 is composed of an electrically conducting element 23, which in turn is composed of a sheet of clear plastics 24, which supports a sandwich 25 composed of two outer films made of semiconducting material that contain a central layer made of metallic material, which constitutes a large electrical resistor which, as will become apparent, when supplied with electric power constitutes the element that provides heating by radiation.

The central layer made of metallic material can be made of silver, for example, and is deposited by means of one of the ordinary known methods for depositing a thin film of metallic material.

The two outer films made of semiconducting material may be provided by means of metallic oxides, oxide mixtures, doped oxides, et cetera, such as to make the entire sandwich 25 transparent to visible light.

The multilayer assembly 22 also has an infrared-reflective clear sheet 26 that is arranged adjacent to the sheet 24.

As an alternative, the infrared-reflective sheet 26 can be embedded within the conducting sandwich 25.

In another embodiment, instead of the infrared-reflective sheet 26, it is possible to provide the conducting sandwich 25 so as to integrate the infrared-reflective property in symbiosis with the electrical conduction property.

The electrically conducting element 23 and the sheet 26 are embedded between two clear sheets 27 and 28 made of polyvinyl butyral (PVB) or equivalents, which by way of known methods using heating and pressure monolithically couple all the components of the glazing unit 10.

A glazing unit 10, when the metallic layer of the sandwich 25 is supplied with current in a manner explained hereinafter, emits thermal radiation particularly on the side of the pane 20, since the radiation directed toward the pane 21 is reflected to a large extent by the sheet 26.

It is known that the feeling of well-being in relation to temperature that the person 19 perceives is linked to the radiation that affects that person's face, trunk and hands and, to a lesser extent, his abdomen and legs.

For this reason, in the solution according to the invention the sandwich 25 where the heat radiation is generated has a variable thickness and a consequent variability of the emitted radiation is achieved in relation to this variable thickness.

By way of indication, Figure 2 illustrates this situation of variable-amplitude radiation, visualized by means of vectors 29 whose length is proportional to the intensity of the emitted radiation.

The envelope of the vertices of the vectors 29 produces a chart 30 that plots vertically the emitted radiation.

By way of example, three regions respectively of maximum radiation 31 are indicated, located at a height that corresponds to the face 32 and chest 33 of the typical person 19.

Above this region 31 up to the ceiling 15 there is a reduced thickness of the sandwich 25 that produces a region 34 with low radiation emission.

Below the region 31 down to the floor 13, there is again a reduced thickness of the sandwich 25, but this thickness is in any case grater than the thickness of the region 34, accordingly forming a region 35 with medium radiation emission at the abdomen 36 and legs 37 of the person 19.

The metallic layer contained in the sandwich 25 is supplied with electric power as shown schematically in Figure 5.

Conveniently, along the sides 16 and 17 of the glazing unit 10 there are a plurality of electrodes, designated in pairs by the reference numerals 38a and 38b for the first pair, 39a and 39b for the second pair, and 40a and 40b for the third pair; while all the other pairs are not numbered but are substantially equivalent.

The pairs of corresponding electrodes lead, by means of electrical conductors designated by the reference numerals 38c and 38d for the first pair of electrodes, to a controlled power supply 41, which in turn is connected to the electrical system 42 of the building.

The electrodes that belong to the same pair, such as for example the electrodes designated by the reference numerals 38a and 38b, conveniently have the same length and the current that arrives from the power supply 41 flows in the conducting part of the sandwich 25, affecting a band that is practically equal to the breadth of the electrodes.

All the electrodes that form the individual pairs may have the same length, but in particular cases it is also possible to use electrodes that have a different length in order to concentrate or dilute the current that circulates always under the control of the power supply 41, which conveniently can be of the inverter type.

By controlling the current and voltage in each pair of electrodes and by taking into account the different resistivity in each region caused by the different thickness of the conducting layer it is possible to have different heatings and therefore different emitted radiation.

The combination of all these variables, controlled by a microprocessor-based system which can also have environmental situation sensors, allows to optimize and concentrate the emitted radiation where this is necessary, in order to achieve with the lowest possible consumption the maximum possible heating, i.e., the maximum sensation of heat.

As mentioned, not all the radiation emitted toward the pane 21 is reflected by the film 26, and therefore the entire glazing unit is also heated and this avoids the formation of condensation or misting particularly in cold periods.

In summer conditions, the film 26 reflects solar radiation outward, allowing to have the additional advantage of reducing the load on the conditioning system of the enclosed space.

With reference to Figure 6, the glazing unit can be used as a glazing for motor vehicles, for example the front driver-side window 30 of a car 31.

The electrodes 32 are arranged on the lateral edges of the windows and are connected to the battery of the car.

The following experimental test was conducted in order to verify the feeling of well-being perceived by the driver.

Starting from an external temperature of 0 °C after an electrical heating time of approximately 6-8 minutes for the glazing unit, which had a specific resistance of 4.5 watt/dm and a power supply of 12 volts, the temperature of the cabin at the level of the steering wheel was approximately 20 °C, offering a feeling of well-being to the driver whose hands and face were directly exposed to the radiation of said window.

The initial external temperature was 0 °C.

The glazing unit that is most effective in terms of heat transmitted toward the internal environment depending on the type of layers of glass used and on the relative position of the conducting sandwich 25 with respect to said layers has been sought experimentally.

It is evident that the heat in the internal enclosed space depends mostly on reducing the flow of heat from the heating element inside the glazing unit toward the outside environment through the thickness of said glazing unit.

The experimental step has found that the maximum effective temperature difference between the inside environment and the outside environment, approximately 30°C, is achieved with a glazing unit, designated by the reference numeral 40 in Figure 7, that is constituted by a double-glazing unit 41 which has, toward the outside, a monolithic glass pane 42 of appropriate type and thickness, is centrally provided with a chamber 43 with dry air or a suitable gas, and is provided toward the inside with a multilayer glass pane as shown in the first described embodiment, i.e., first and second glass panes, designated respectively by the reference numerals 44 and 45, which contain a multilayer 46 with an embedded heating conducting sandwich 47.

A further experimental test was conducted in order to validate the invention.

This test was meant to detect the feeling of well-being perceived by a human hand during a temperature variation inside a certain enclosed space.

With reference to Figure 8, this enclosed space was simulated by providing a cube with three radiant walls A, B, C, structured according to the first embodiment of Figure 4 and lacking at the front a fourth wall in order to allow the insertion of said hand inside it.

It has been found that when bringing the walls to a temperature higher than 35°C in less than 4 minutes, starting from a situation in which the overall temperature was 0 °C, the hand perceived a feeling of well-being regardless of the external temperature and the internal temperature, which after 4 minutes was still well below 20 °C.

From what has been described and illustrated it can be noted that the intended aim and objects have been achieved and that in particular a heating element has been provided which can concentrate the emitted radiation at a level that can be chosen according to the enclosed space and to the activity performed in the enclosed space.

The solution adopted for the glazing unit can be provided by means of known technologies and allows to heat enclosed spaces of any kind with a very high yield indeed because the heat is directed where it is needed.

Naturally there may be many embodiments that start from the same inventive concept and in particular such embodiments must adapt to the enclosed spaces and/or rooms to be heated.

The materials and dimensions may be any according to requirements.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.