DESCRIPTION

Technical field of the Invention

The scope of application of the present invention concerns the air purification and sanitization systems of indoor environments, i.e. all those confined spaces in which people are expected to stay: private homes, public and private offices, community structures (hospitals, schools, barracks, banks), environments intended for recreational and social activities (cinemas, bars, restaurants, shopping centers, sports facilities) and public and private means of transport. Particular attention is paid to the application in the hospital environment, an environment in which the need to have efficient sanitation systems with respect to the presence of viruses assumes a very significant importance. A brief description of these organisms is proposed below, aimed at a better understanding of the inventive concepts then exposed. Viruses are obligate parasitic acellular microorganisms. In fact, these infectious nucleoprotein particles lack their own cellular structure and replicate only by exploiting metabolic intermediates, enzymes and organelles of the host cell. Although they are to be considered metabolically "inert", viruses can still survive in the external environment and remain there for a limited time (even a few hours). The viral particle - when it is extracellular - is called virion; on the other hand, when it is in a phase of active intracellular replication it is called a virus. Virions, therefore, are found almost everywhere, in the air, in food and in the environment, while viruses are confined within the cells - animal, plant or bacterial - that host them.

The basic structure of a virus is made up of a nucleus enclosed by a protein coat called capsid. The nucleus is made up of genetic material, that is a nucleic acid, which can be DNA or RNA, but never both at the same time; hence the substantial difference between the two types of viruses, which are discriminated by the particularity of their genetic heritage and therefore by the replication mechanism. Hence, there are DNA viruses and RNA viruses; each type can be single or double stranded of genetic material. Single-stranded RNA viruses are further divided into polarity (+) and polarity (-) RNA viruses. Usually, DNA viruses replicate in the host cell nucleus while RNA viruses typically replicate in the cytoplasm. However, some (+) polarity single-stranded RNA viruses called retroviruses use a different method of replication.

Retroviruses use reverse transcription to create a double-stranded DNA (provirus) copy of their RNA genome, which is then inserted into their host cell's genome. Since RNA transcription does not involve the same error control mechanisms present during DNA transcription, RNA viruses, particularly retroviruses, are very prone to mutations.

Therefore, in the case of viruses with incomplete RNA genetic heritage, replication occurs with an intermediate step of conversion of the RNA strand into DNA; subsequently, this viral DNA integrates into that of the infected organism (e.g., in the case of a hospital environment, the human organism) by means of an enzyme, entering the genetic heritage of the cell that hosts it.

Due to the complexity of the matter, it is in fact impossible to propose or suggest a single solution, which can be identified as a unique strategy, designed to prevent the propagation of the external "parasite".

Moreover, in the case of "RNA viruses", the scientific community is unanimous in considering them particularly sensitive to genetic mutations, therefore highly unstable and dangerous. Therefore, the present invention, in front of all these aspects, has posed, as a central problem, the need to counteract a great heterogeneity of pathogens, parasites and infectious agents, in order to conceive a combined multistage disinfection system against unwanted guests. Since there are many possible opponents, the invention intends to apply the popular adage: "unity is strength".

Prior Art

Every day, a large number of people, often out of necessity, have to spend most of their time indoors; so much so that a sensitivity to the issue of indoor air pollution is gradually developing. However, the attention to this issue is still not enough when compared to the extent of the problem, given that indoor air pollution is potentially more harmful than outdoor pollution.

In addition to the need to sanitize the air in indoor environments, it is also important to ensure a healthy and comfortable microclimate, that is, to ensure a correct room temperature, adequate air circulation and a controlled humidity rate. This is possible by making use of mechanical ventilation systems that make it possible to contribute to the achievement of correct environmental hygiene conditions, and internal comfort.

However, relying only on the air movement of common fans or air conditioning in summer, is insufficient because these systems move and put back in suspension particles of dust, mites and microorganisms, without exchange with the outside air; it is therefore also necessary to couple filtering and air sanitizing systems.

More and more consolidated studies clarify the importance of controlling the air quality in indoor environments, and generate an increasing awareness that environmental well-being has certain repercussions on the performance and psychophysical balance of the people who occupy these environments. A first risk factor, determined by poor air quality, is linked to the presence in the air of the so-called human "bio-effluents", i.e. chemical compounds that are emitted by the human body in the form of water vapor, carbon dioxide, esters, alcohols, aldehydes, methane, sulfur compounds, fatty acids, etc. For example, patients and medical staff of a hospital spend all their time inside wards or rooms not adopting suitable forms of air recirculation, causing a progressive deterioration of the quality of the same due to the increase in the concentration of "bio-effluents". These, while hardly ever reaching concentrations harmful to health, are classified as air contaminants when there are relatively high concentrations. A second factor that has an impact on air quality is given by the so-called PM (Particulate Matter), which is a set of solid and liquid particles that are suspended in the air. PM can originate both from natural phenomena (soil erosion processes, forest fires, dispersion of pollen, etc.) and, and mainly, from anthropogenic activities, in particular from combustion processes and vehicular traffic (primary particulate matter).

There is also a particulate of secondary origin that is generated in the atmosphere by the reaction of other pollutants such as nitrogen oxides (NOx), sulfur dioxide (S02), ammonia (NH3) and the so-called Volatile Organic Compounds (VOC), to form sulfates, nitrates and ammonium salts. Microorganisms spread by air currents in indoor environments (including "bioeffluents"), and mostly transported adhered to suspended particulate matter, can be harmless to healthy people, but cause infections in individuals with immune deficiencies.

The PM (i.e. the main set of suspended particulate material) can remain suspended in the air for a long time, especially in the presence of air currents, air currents which are however important from other points of view, such as the regulation of the temperature, or humidity control which, in turn, is linked to the formation of mold and the proliferation of other microorganisms.

Even the air conditioning systems, the human activities carried out in the various areas and the presence of people suffering from diseases can affect the quality of the air circulating.

In short, the problem of controlling air quality, both from the health point of view and from the point of view of its impact on environmental comfort and, ultimately, also from the point of view of energy efficiency, is a complex problem, and of great importance.

The known technique proposes many solutions, which however, with respect to the general complexity of the problem, solve some partial aspects of the problem understood in its amplitude as briefly outlined above.

The statement that the sanitization of the air in indoor environments, and more generally the control of air quality, is a problem to which increasing importance is being attributed, is also underlined by the fact that, in an increasing number of contexts, a specific legislation is rising a that requires the control of certain parameters related to air quality.

The use of systems of ventilation and conditioning with controlled contamination (VCCC), according to the known technique, are not yet sufficient to achieve satisfactory control of air quality.

The levels of VOC (Volatile Organic Compounds) present in the environments of any building can be controlled upstream through a correct and thoughtful choice of building and furniture materials, but, above all, of the systems and infrastructures serving the building. The scientific community, in addition to the many advice on the choice of the most suitable construction materials and products, recommends paying particular attention to:

- the adequate ventilation of the premises when there are possible sources of VOCs, during and immediately after the laying of construction materials or the installation of new furnishings (e.g. furniture, carpeting, coverings);

- always keep the rooms well ventilated;

- equip these rooms with regularly maintained mechanical ventilation systems.

Ultimately, it is necessary to resort to a plurality of precautions, including, of particular importance, to guarantee a constant recirculation of air between the internal environment and the external atmosphere (a measure which, by itself, is able to ensure good levels of living comfort).

Most of the known systems, which can be used to manage air quality, therefore require combining mechanical ventilation systems for air recirculation with filtering systems to be suitably placed in the air intake ducts, and these systems generally require a fairly complex design. Typically, they are systems designed ad- hoc for individual environments, which is not easy combined with the energy requalification interventions of existing and old-concept buildings.

The energy requalification of existing buildings, in fact, is increasingly widespread, given the increase in the costs of energy and related infrastructures. Often these interventions also include the replacement of the fixtures and the insulation of the building envelope. It therefore happens that even dated buildings can become airtight and the air exchange is no longer guaranteed. The result is the accumulation of humidity in the rooms which can lead to the formation of odors and mold on the walls. In such situations, in which the management of air quality is particularly important, the known art does not offer easily applicable solutions.

A further problem that occurs, in general, in known solutions of air filtration and sanitation concerns the maintenance aspects. In fact, the filters get dirty and degrade their performance during their use, then they need to be regularly replaced or washed. These maintenance processes lead to uneven performance over time, alternating optimal filtering phases (with a clean filter) with inefficient filtering phases (corresponding to the periods immediately preceding the maintenance of the filter elements). Precisely in order to meet the needs of safeguarding and healthiness of living spaces, in such a complex context as that of air quality, the system taught in the present invention is placed, which combines respect for comfort and healthiness of the air, with themes of thermal efficiency. It is therefore also proposed as an advantageously applicable element in the context of an overall management strategy of the energy efficiency of a building, and it is applicable to a large variety of environmental contexts.

Among the known art documents, which are considered somehow relevant for the purposes of the invention described below, it’s worth mentioning EP 2 119 974 A1 (“A method and device for cleaning air” - Johnson M.S. et al. [SE] - 18 November 2009).

Summary of the Invention

The general purpose of the present invention, therefore, is to indicate an innovative "integrated" system of mechanical controlled ventilation (MCV) and of air sanitation; that is, a wall system that guarantees a constant exchange of clean air in indoor environments, and that is more advanced than the systems available on the market.

In particular, the air sanitization system according to the invention must be able to introduce air taken from the outside into an indoor environment, decontaminating it from all the main elements harmful to human health, such as various types of microorganisms, VOCs, various particulates in air suspension, PM, etc.

In addition, the air sanitation system according to the invention must be able to expel air from an indoor environment, recovering as much heat as possible, which would otherwise be dispersed outside with a significant waste of energy.

A further purpose of the present invention is to indicate an air sanitation system that is easy to install, even in existing environments, without the need for overly invasive works.

Again, a further purpose of the present invention is to indicate an air sanitation system that is easy to maintain, so that its performance remains as homogeneous as possible over time.

The aims set for this invention are achieved by resorting to an air exchange and sanitizing system suitable for being installed on a delimiting wall between an internal and an external environment and which includes: a main duct that allows the passage of the air between said internal environment and said external environment, and a mechanical forced ventilation subsystem adapted to force both the passage of air from the inside towards the outside and from the outside towards the inside; and said air exchange and sanitation system is characterized in that it also includes: i. a first stage of air disinfection, located inside said main duct, in which the air that passes through it from the outside to the inside is mixed with ozone gas (03), ii. a second stage of air disinfection, located inside said main duct, in which the air passing through it, from the outside to the inside, is invested with radiation in the ultraviolet spectrum, iii. a third stage for filtering and sanitizing the air, located inside said main duct, in which the air passing through it also passes through a septum consisting of a material with filtering, oxidizing and antibacterial properties, and, when said air exchange and sanitization system is installed inside said boundary wall, said three stages are placed inside said main duct in such an order that the incoming air, coming from the external, passes through said first and second stage before passing through said third stage, while the outgoing air, coming from the inside, first passes through said third stage and, subsequently, through the main duct section occupied by said first stage and second stage.

The main advantage of the present invention is that an air exchange and sanitization system according to the teachings of the present invention allows to satisfy all the purposes for which the invention was conceived.

This invention also has further advantages, which will become more evident from the following description, from some examples of practical embodiments which illustrate further details, from the attached claims which form an integral part of the present description, and from the attached Figure 1 in which the air exchange and sanitization system according to the invention is schematically shown, by highlighting some of the main elements that constitute it. Detailed Description

Figure 1 presents a schematic diagram of the air exchange and sanitation system according to the invention, which is indicated as a whole with the number 100.

Said air exchange and sanitization system 100 is suitable for installation by making an opening in a perimeter wall of a building, i.e. a delimiting wall between an internal environment, indicated with the number 300, and an external environment, indicated with the number 200. Since said air exchange and sanitization system 100 must be mounted with the correct orientation, in Figure 1 the external side (outdoor) is highlighted in the left part of the figure, and the internal side (indoor) in the right of the figure.

Said air exchange and sanitization system 100 comprises a main duct which allows the passage of air between said internal environment 300 and said external environment 200. Already from this first characteristic, the simplicity of installation can be highlighted, being the installation substantially local, since it only requires to bring to the installation point the electrical power supply, which can be provided with relative ease.

Furthermore, the system can be powered continuously at 48V; therefore, for quick installation interventions or for “field" application contexts, in temporary structures, it can be powered directly by a photovoltaic system or by a battery.

The correct functioning of said air exchange and sanitization system 100 requires that the passage of air between the two rooms, inside 300 and outside 200, takes place in a forced and controlled manner. For this to happen, the overall system requires the presence of a mechanical subsystem of forced ventilation, indicated in Figure 1 with the number 140. Said mechanical subsystem of forced ventilation 140, generally, but not necessarily, consists of a suitably shaped fan, which is made to rotate, normally placed at one of the two ends of said main duct, preferably on the internal side, just for maintenance convenience.

The elements mentioned so far only serve to produce a recirculation of the air, making it enter or exit the internal environment through the main duct, and controlling its flow by means of said mechanical subsystem of forced ventilation 140. The exchange and sanitization system of the air 100 according to the invention, however, must also provide for a control of the air quality and must limit as much as possible the energy waste that would take place with a simple recirculation of the air, due to the different temperature to be maintained in the internal environment 300, compared to the temperature present in the external environment 200.

Air sanitization is implemented through the combined contribution of three actions: an ozone disinfection, a disinfection system with ultraviolet radiation and a filtration and oxidation system in silver, or other material with similar properties. As for the ozone disinfection, it is noted that it is a very effective treatment that can be implemented by producing ozone (03) starting from the oxygen present in the air: it is observed that the production of ozone is based on a very simple process of molecular oxygen ionization (02). Therefore, the air exchange and sanitation system 100 also includes an ozone gas production subsystem indicated in Figure 1 with the number 150. The ozone gas thus produced can be diffused inside the main duct in a first stage of this, indicated with the number 110.

Ozone is a highly unstable natural gas, composed of oxygen (3 oxygen atoms) and with a great oxidizing power. Chemical oxidation is in fact the mechanism underlying the process of degradation and elimination of organic substances such as viruses, bacteria, pathogens and fungi, and actually prevents their replication and spread.

Being an unstable gas, a few minutes after use, the ozone transforms into molecular oxygen without leaving any kind of traces or chemical residues, without leaving unpleasant odors or stains where it is deposited.

Since ozone is a gas heavier than air, it is able to penetrate inside the fibers of the fabrics and in the places where other systems would disperse their disinfectant power; it has been calculated that the sanitization results obtained through ozone sanitation are 2000 times higher than those obtained through traditional systems.

In Italy, the Ministry of Health, with protocol No. 24482 of 31/07/1996, recognized the ozone sanitation system as a natural safeguard for the sterilization of environments contaminated by bacteria, viruses, spores, etc. and infested with mites and insects. Therefore, the integration of the air exchange and sanitization system 100, according to the present invention, with an ozone production subsystem 150, combines the effectiveness of the management in the recirculation of air in indoor environments, with a sanitation of spaces for the users.

In a variant of the air exchange and sanitization system 100 according to the invention, the ozone produced with the subsystem 150 can be diffused as well as inside the sanitization stage 110 (in the main duct), in order to disinfect the incoming air introduced into the internal environment 300, also directly into the internal environment 300, particularly when these rooms are not manned, given the useful effects it produces. Obviously, when the room is manned, the production of ozone introduced into the environment must be calibrated, also according to the quantity of air that passes inside the main pipeline. Only in the case of deep sterilization the production of ozone may be increased in order to achieve the purpose, but taking care to provide for the evacuation of people within the environment to be sterilized (absence of people which must last only for the short period in which the sterilization is actually carried out, as the ozone, as mentioned, is rapidly transformed into normal molecular oxygen (02)).

In this variant of the air exchange and sanitization system 100 according to the invention, in which the ozone is also directly diffused in the internal environment, the presence of a sorting element, indicated with the number 151 , which can be controlled to convey the ozone produced, in whole or in part, inside the sanitation stage 110 when it is on, and also conveys it (all or in part) directly into the internal environment 300, depending on the opportunity.

The second disinfection treatment takes place using ultraviolet (UV) radiation which is always propagated on the incoming air that passes through the main duct. In Figure 1 , the stage in which this second disinfection treatment takes place is indicated with the number 120.

The strength of this system lies in that it operates without the use of invasive chemicals.

UV represents the wavelengths that fall between visible light and X-rays on the electromagnetic spectrum; in this system the UV component is further broken down and divided into wavelengths between 200 and 280 nm.

This breakdown allows UV-c photons to penetrate and damage the nucleic acid of the "parasitic" cells, significantly weakening them and making them unable to reproduce and therefore microbiologically inactive. The LED (Light Emitting Diode) technology allows to produce a dense and uniformly distributed electromagnetic spectrum of photons whose UV-c rays are able to inactivate viruses and pathogens in a few seconds.

Just as LED lighting systems have represented an evolution in the panorama of domestic and non-domestic lighting, the use of the same technology, appropriately contextualized, will be placed as a resource in a scenario in which the guarantee of sanitation of public spaces will become essential.

From 2016 onwards, numerous studies have been published that demonstrate the effectiveness of UV-c technology against even very resistant bacteria, which cause infections in hospitals. In particular, in this regard, reference should be made to the research programs conducted in Italy by the Department of Molecular Medicine and Bioengineering Development of the Medical Biotechnology Department of the University of Siena and by the University of Rome “Tor Vergata”. With reference to the rest of the world, please refer to the works proposed by the Columbia University Medical Center in New York and by the Graduate Institute of Environmental Health of the University of Taipei in Taiwan.

The "Ultra-Violet Germicidal Irradiation" (UVGI) is therefore a recognized sterilization method, which uses ultraviolet (UV) light at the UV-c wavelength, and which modifies DNA or RNA microorganisms and therefore prevents them from reproducing or being harmful. From a practical point of view, the desired UV radiation can be produced using a sequence of LED rings that radiate inside them; these rings are coupled to each other to form a conduit of variable length (depending on the number of rings that join) and in fact constitute the second disinfection stage 120.

There are no particular constraints in the order in which the two disinfection treatments must be carried out, with ozonation and UV radiation. In a variant of the air exchange and sanitization system 100 according to the invention, the two treatments could also take place simultaneously, it being theoretically possible to diffuse the ozone gas in the same space in which the ultraviolet radiation is propagated. On the other hand, it is important that the last filtering and sanitizing stage consists of a third stage, indicated with the number 130, placed inside said main duct, in which the air that passes through it, has already been treated with the previous methods, and just after that it passes through a physical filtering layer, consisting of a material with filtering and, at the same time, oxidizing and antibacterial properties. In fact, the disinfection treatments carried out in the first two stages 110 and 120 do not exhaust the sanitization that is to be obtained. In particular, in the air coming from the external environment, as illustrated at the beginning of this description, there are also other substances not sufficiently attackable with the above methods, such as, for example, the so-called PM (Particulate Matter) set of solid and liquid particles (particulate) that are suspended in the air.

Furthermore, the action of UV radiation depends on the duration of exposure, to the radiation itself, of the particles to be attacked. For reasons of recirculation speed, and for reasons of space, which limit the length of the disinfection stage 120 to UV radiation, the exposure time of the molecules to be attacked is not always sufficient, and the result obtained is often a strong weakening of these molecules, but not their complete neutralization.

Consequently, a further physical filtration stage is necessary, in which the incoming air is passed through a filter material with suitable oxidizing properties, which retains the PM and which, reacting with most of the pathogens treated with the previous methods, provides for their neutralization. A material having characteristics, today considered optimal, suited to be used in the production of this filter, is silver. A preferred implementation to achieve this filtering stage consists in using a porous ceramic septum on which pure silver is deposited, or copper and silver filters, or even porous plates in pure silver (indicated, the latter, for medical environments or biological laboratories).

The invention, in general, can be implemented by resorting to different materials to make the filtering septum of the third stage 130. The important thing is that the material used has a considerable porosity, so as to develop surfaces in contact with the air of the order of square meters, compared to sections of the duct whose width can be of the order of ten (or a few tens) of centimeters; and this exchange surface must be made of a material which also exhibits disinfectant and oxidizing properties. The intrinsic characteristic of silver is that it is naturally present in ionic form (Ag +), biologically active, and has the ability to irreversibly damage the cell membrane, RNA and DNA of viruses, bacteria and spores, inactivating metabolic processes which guarantee the survival of the "host" cell. Damage to RNA, in particular, is particularly effective for disinfection of various types of viruses, including coronaviruses.

The suspended particles (i.e. PM), on the other hand, due to the previous ozonation treatment, which tends to ionize them negatively, are attracted by the silver surface and are retained by the filter.

In relation to air filtration, silver, in combination with oxygen, in conditions of minimum humidity, therefore acts as a powerful disinfectant that offers a significant enhancement of other disinfectant systems.

Finally, it is highlighted that silver does not react with organic compounds, and therefore there is no risk of creating harmful by-products. It is observed that the first two disinfection stages 110 and 120 can be switched off, by interrupting the ozone input in the first stage 110 and by turning off the UV emitting LEDs in the second stage 120. It is clear that, normally it is not necessary to sanitize the air at the outlet from an internal environment, and therefore when said mechanical subsystem of forced ventilation 140 forces into the main duct a flow of air coming from the inside 300, and expels it towards the external environment 200, said first stage of air disinfection 110 and said second air disinfection stage 120 are off. On the contrary, they are turned on when said mechanical subsystem of forced ventilation 140 is in suction mode, that is when it forces an air flow from outside 200 into said main duct and conveys it to the internal environment 300.

Both the control of the mechanical subsystem of forced ventilation 140, which allows to alternate the inlet and outlet air flows, and the various on and off commands of the various disinfection stages are managed by means of suitable computing means, indicated in Figure 1 with the number 170.

Said computing means 170, in fact, control all the controllable components present in the air exchange and sanitization system 100 according to the invention, and therefore they control the subsystem 150 for the production of ozone gas, as well as the sorting system 151 , which introduces the ozone produced inside the first disinfection stage 110 (when switched on) or directly into the internal environment 300 when there are the conditions that require it. In general, it can be summarized that said computing means 170 execute programs that implement the operating sequences of the entire air exchange and sanitation system 100 according to the invention. These sequences can be predefined, or manually programmed by an operator, through appropriate interfaces, as well as they can be calculated on the basis of air sanitation needs measured in real time. In fact, the air exchange and sanitization system 100 according to the invention (and in particular the computing means 170 integrated therein), in some forms of implementation of particular interest, interfaces with a network of sensors capable of measuring significant parameters about the air quality of an indoor environment.

Consequently, said computing means 170 can process this information and calculate specific operating sequences of the air exchange and sanitization system 100: in such a way that these sequences are optimal for improving the air quality of the indoor environment 300.

In some variants of implementation of the present invention, it is possible to provide for two or more air exchange and sanitization systems to be installed in an environment, for example in different points of the same indoor environment. In this case, it is appropriate that their operating cycles, which also regulate the introduction and emission of air, are coordinated by centralized computing means: ultimately, in some variants of the present invention said computing means 170 activate the operating sequences of a plurality of air exchange and sanitization systems.

A further feature regards the material with which the air filtration is made in said third stage 130; it is that this material must have significant conductivity and thermal capacity. In fact, the passage of air inside a filter with these thermal properties (it is noted that silver is an excellent thermal conductor), also allows for the creation of a very efficient heat exchanger for energy saving purposes. In fact, in the event that the internal temperature is higher than the external one, the outgoing hot air will release heat as it passes through this filter, cooling down before escaping; heat that can be recovered from the incoming air, which will then be introduced into the internal environment 300 heated with respect to the external temperature.

Mutatis-mutandis, a similar thermal regulation effect (with consequent energy saving) also takes place if the internal temperature must be kept lower than the external temperature.

With reference, now, to the overall maintenance of the air exchange and sanitization system 100 according to the invention, it is noted that this is, in general, particularly easy. In fact, the mechanical subsystem of forced ventilation 140 is a very simple and reliable mechanism, and it can be positioned so that it is easily accessible and possibly removable for repairs, washing or replacement.

The first two disinfection stages 110 and 120 have no moving parts, they can be made with very high reliability, and do not require special cleaning maintenance. The only element subject to getting dirty, and which requires maintenance, is the third stage 130 of filtering and sanitizing of the air, which is located inside said main duct, but close to its internal end, therefore in an easily accessible position. However, cleaning maintenance of the filter contained in said third stage 130 of filtering and sanitizing the air, based on periodic interventions, has the typical contraindication of all filtering systems: these provide the best performance with a clean filter, performance which gradually deteriorate as the filter becomes dirty, until the next maintenance intervention, when the best performances are restored, thus determining non-homogeneous performances over time, unless very frequent maintenance interventions are foreseen, which can be inconvenient, as well as increase costs associated with maintenance. In a particularly efficient implementation variant, the air exchange and sanitization system 100 according to the invention provides for the presence of a subsystem, indicated in Figure 1 with the number 160, for the generation of ultrasonic or subsonic vibrations, which are propagated on said third stage 130 of filtering and disinfecting the air.

It is observed that, in one of the preferred embodiments, said vibration generation subsystem 160 is a very simple and very reliable component consisting of a pair of ceramic plates cohesive with the filter body (which, as noted previously, is also a heat exchanger), and suitable for inducing a vibration to the body to which they are applied. This vibration generation subsystem 160 is configured, case by case (depending on the material used to make the filter), to generate a vibration frequency close to one of the critical frequencies of the material of which the filter is made, so as to induce a resonant vibration on the filter body. At the same time, the mechanical forced ventilation subsystem 140 is controlled to generate an outgoing "washing" air jet, which passes through the vibrating filter, removing deposited particles, whose cohesion with the filter walls is weakened by effect of the vibrations. In addition, the generation of ozone ions (which can be produced on-site with the generator 150) can also be exploited, which can "enrich" the "washing" air, increasing its cleaning effect, and obtaining deoxidation of the exchange surface. Obviously, in this implementation variant, which integrates an automated filter cleaning function, the geometric configuration of the air exchange and sanitization system 100 according to the invention can be organized in various ways, however, in a simple implementation form, ozone can be introduced into the air in the internal environment 300, in an area close to the fan of the mechanical forced ventilation subsystem 140, so that the air sucked in and then blown to clean the filter is already enriched with ozone.

In summary, the form of implementation described above is particularly advantageous, because it adds a constant action system, complementary to the ordinary maintenance of the filter, i.e. removal and installation of a new filter septum, after its filtering power has degraded excessively due to accumulation of inert material. This mechanism allows to extend the useful life of the filter (before it needs to be removed for its cleaning and regeneration) and, above all, guarantees an effective functionality of the same more efficient than that which similar systems can offer, with a consequent reduction in management costs.

Ultimately, the air exchange and sanitization system 100 according to the present invention solves an important technical problem which consists in controlling the air quality of an indoor environment 300 with speed and efficiency. In fact, the various treatments to which the flow of air entering the indoor environment 300 is subjected, if used individually, are all insufficient to obtain satisfactory control: both because each is effective only with respect to certain substances that degrade the quality of the air, and because they would require longer treatments or more voluminous treatment environments in relation to the quantity of air to be treated. The combination of the treatments integrated in the air exchange and sanitization system 100 according to the invention allows to synergistically exploit the effects of each treatment, so that the filtering and sanitizing effect is greater than the simple sum of the effects achievable with each treatment carried out individually. This is because the various substances that are attacked for air treatment are affected precisely by the combined effect of the various treatments in sequence: in particular, part of the action of the third stage in silver would not take place if the incoming air was not ozonated, as well as the disinfectant attack of silver is certainly more effective due to the fact of acting on cells already damaged by the action of ultraviolet radiation.

Furthermore, the practical and real implementation of the inventive principles allows the integration of a particularly compact and fast system: in fact, it is precisely the sequence of the various treatments that allows to speed up the effects of the actions implemented in each stage.

With regard to the compactness of the system, then, it is highlighted how the same system can be used in the two directions of air recirculation, inlet and outlet, being able to alternate air inlet and outlet (therefore the recirculation) with fully controllable rhythms.

Not only that, the various component parts of the system actively contribute to the achievement of other additional objectives, other than the main objective which consists in controlling the air quality, more accurately than is done with the known technique. Among these:

^ the attention to maintaining the comfort of the internal environment, given that the incoming air it recovers (or releases) heat before entering, so that there is no sensation of drafts in the areas affected by the introduction of air from the outside; the attention to energy efficiency, due to the presence of an element that acts as a heat exchanger, and which mitigates the waste of energy for maintaining the temperature of the internal environment 300, while maintaining ventilation of the environment; the attention to the aspects of management and maintenance of the system. Concluding Remarks

Ultimately, the air exchange and sanitization system 100 made according to the teachings of the present invention, compared to the traditional solutions proposed by the known art, appears to be very effective for improving the air quality of an indoor environment from different points of view: sanitary, comfort, and the energetic efficiency.

In general, then, the present invention lends itself to numerous variations while maintaining the claimed prerogatives. In fact, it can be developed in different sizes, and, as already mentioned, it can include different pipes coordinated with each other by the same control unit to manage air recirculation with greater homogeneity and efficiency.

Furthermore, the invention itself can be realized partially, as well as the reciprocal position of the various elements described can be modified; moreover, each element can be developed in different materials, shapes or sizes, and many of the described details can be replaced by technically equivalent elements.

In particular, the use of specific materials with different filtering or disinfectant properties is not an essential part of the present invention. Therefore, if in the future the materials sector will make available new materials’ technologies, more advantageous than those mentioned in the preferred implementations, in order to implement the present invention more efficiently, for example with the development of new more efficient materials or cheaper than silver, further improvements could be made without changing the inventive nature and the principles that inspired the invention itself.

Other possible variants for the present invention could be linked to the evolution of electronic technologies in general (which are evolving towards a greater and greater miniaturization and lower power requirement), so that, for example, the air exchange and sanitization system 100 indicated in the invention could integrate sensors capable of regulating the operation of the various subsystems that compose it according to more optimized sequences. In addition, components of varying complexity could be integrated, being capable of performing other functions, additional to the air exchange and sanitization function.

Therefore, especially in the context of such evolutionary scenarios, the invention lends itself to incorporating and supporting further development and improvement efforts, capable of improving the performance of the system described. Therefore, many further developments can be made by the man skilled in the art without thereby departing from the scope of the invention as it results from this description and the attached claims, which form an integral part of this description; or, if said developments are not included in the present description, they may be the subject matter of further patent applications associated with the present invention, or dependent on it.