TECHNICAL FIELD

The present invention relates to a natural air purifier in which the purification takes place through a plant and the culture matrix thereof. A ventilation system optimizes the air filtration. In this regard, the air purifier comprises

(a) a first flower pot and a second flower pot which is housed inside the first flower pot wherein

(al) the second flower pot is provided with one or more holes; and (a2) the second flower pot is provided with an opening;

(b) a control unit housed in said opening and comprising:

(bl) a fan and preferably a grid covering said fan with respect to the outside of said first flower pot; and optionally

(b2) a temperature sensor;

(b3) a humidity sensor (40);

(b4) an air quality sensor (36); and

(b5) a microcontroller (34) suitable to receive data from the sensors (36, 38,

40) and to send signals to the fan (32; 432).

STATE OF THE ART

To make the atmosphere in living or working spaces healthy, the market has developed various types of air purification devices. In general, air purifiers are devices that eliminate from air through filters of different types contaminants, toxic agents, powders, VOCs (Volatile Organic Compounds), etc. A natural air purifier is a device that uses the roots of plants or also the matrix in which they grow as filters.

In the roots there are microorganisms that actively biofiltrate toxic agents and decompose them. Currently available natural air purifiers promote the transport of air to the roots and/or culture matrix with ventilation systems integrated in the pots, as described, e.g., in US documents US 2015/0282436 Al, US 6,230,437 Bl and US 2011/0154985 Al. In these systems the airflow is not optimized within the pot which contains the plant and the matrix. DISCLOSURE OF THE INVENTION

The object of the invention is to propose an improved air purifier for purifying the air in internal spaces, in particular an air purifier with an optimized air flow to the roots and through the matrix in which the roots are rooted. This and other objects which will become apparent from the following description of the invention are obtained from an air purifier of the initially described type which is characterized in that

the second flower pot comprises a culture matrix containing a mixture of:

(i) an organic matter containing soil, and

(ii) a granular material with a grain size from 0.5 to 10 mm.

The insertion of the second perforated flower pot in the first flower pot creates a space between the walls of the pots and allows a defined airflow in the middle which is channelled through the holes in the second flower pot and through the control unit with the fan.

In an advantageous embodiment of the invention, the air purifier further comprises a first gasket which hermetically closes the space between the upper edges of the two flower pots and optionally a second gasket interposed between the opening in the first flower pot and the control unit inserted therein, thereby realizing a closed space to force the airflow only in the desired spaces and directions avoiding airflow losses.

A mixture of a soil containing organic matter with a granular material increases the airflow within the culture matrix.

Advantageously, the granular material consists of zeolites and pumice. Particularly preferred zeolites are chabazite and phillipsite and mixtures thereof. Zeolites are microporous alumosilicates of natural or synthetic origin. Pumice is a highly porous volcanic rock. The porosity of these minerals promotes the airflow.

Mixtures wherein the organic matter containing soil is present in the mixture in volumetric fractions which vary from 30% to 90%, preferably from 50% to70%, and wherein the granular material is present in volumetric fractions which vary from 70% to 10%, preferably from 50 to 30% are particularly preferred.

Very good results in terms of air purification, i.e. the reduction of contaminants, in particular of isopropyl alcohol and formaldehyde, in the air, have been observed with a granular material which has a volumetric fraction of zeolites of 45-55%, preferably 50%, and a volumetric fraction of pumice of 55-45%, preferably 50%.

The purifying capacities of the culture matrix according to the invention can further be significantly increased if the culture matrix further comprises charcoal.

Advantageously, the charcoal is comprised in volumetric fractions ranging from 0 to 50% in the culture medium. The remaining volumetric fraction of 100% - 50% is occupied by the mixture of organic matter containing soil and granular material. Preferred contents of the charcoal in the culture matrix according to the invention correspond to volumetric fractions of 15 - 35%, in particular about 20%.

Preferably, the grain size of the pumice particles corresponds to diameters between 3 and 7 mm, while the grain size of particles of the zeolites corresponds to diameters between 0.7 and 2 mm. Surprisingly, this choice of grain sizes, despite a certain compactness of the culture matrix, has resulted in the best results in air purification.

Advantageously, the organic matter containing soil has grain sizes which correspond to clays, silt, sand and/or fine gravel. The diameter indicated for the grain size is intended as an equivalent diameter as defined according to DIN 4022 standard, replaced by EN ISO 14688. Preferably, the average grain size of the soil is lower than the average grain size of the granular material used. The organic matter containing soil does not necessarily comprise only organic matter, such as peat, but may also include other materials such as clay or fertilizers. However, the term organic matter containing soil indicates a soil that mainly comprises organic matter, i.e. the greater volumetric fraction, preferably > 50%, is composed of organic matter.

An air purifier according to the invention wherein the microcontroller contains algorithms which calculate from the data collected by the sensors the necessary measures to improve air quality, in particular calculate the temperature, the humidity and/or the velocity of the fan which contribute to improve the air quality, and wherein the microcontroller pilots, preferably via a Wi-Fi module, a room/office heating unit, a room/office air-conditioning unit, a room/office humidifying unit, a self-watering unit of the air purifier, if present, and/or the fan velocity such that the calculated temperature, humidity, fan velocity and/or air quality are obtained, and wherein optionally, the microcontroller contains algorithms which permit the mapping of the collected data in function of time and location and wherein the microcontroller preferably indicates in case of humidity values received from the humidity sensor which drop below a certain threshold value, water shortage in the water tank is able to further optimize the airflow through the culture matrix. The management of the fan velocity and also the management of the air direction through the fan are particularly preferred.

The person skilled in the art easily identifies commercially available suitable sensors which are useful in the air purifier according to the invention. Air quality sensors can be selected between a CO sensor, a C0 ₂ sensor, a VOC (Volatile Organic Compounds) sensor, an NO _x sensor, a SO _x sensor, a particulate matter (PM) sensor for different grain sizes, e.g., PM 2.5 (particulate matter with a diameter of less than 2.5 pm), a pollen sensor, etc.

Preferably, the air purifier further contains a self-watering unit and the microcontroller preferably contains an algorithm which, in case of signals of low air quality from the air quality sensor controls the self-watering unit of the air purifier such that the humidity in the matrix present in the second flower pot is raised. Experimental results also show that high humidity results in an increased air passage and an increased absorption of toxic substances and therefore in an increased air purification.

Advantageously, an air chamber is formed between the outer and inner flower pot, which allows the air to circulate very well inside, to pass several times in the culture matrix and thus to be even more purified; this would not be possible if the inner pot was flush with the outer one, because in that case there would be only one passage, in this case, instead, there are many passages and there is an extensive flow all around.

Another aspect of the invention concerns a culture matrix which includes:

(I) 50 - 100 % of a mixture of:

(la) 30 - 90 % of organic matter containing soil of a, and

(lb) 70 - 10 % of a granular material with grain sizes from 0.7 to 7 mm consisting of (a) zeolites, in particular selected from chabazite and phillipsite and mixtures thereof, with grain sizes which vary from 0.7 to 2 mm, and (b) pumice with grain sizes which vary from 3 to 7 mm; and

(II) 50 - 0 % of charcoal; with a particularly preferred composition of 32% of pumice/zeolites chosen between chabazite and phillipsite; 48% of organic matter containing soil and 20% of activated charcoal,

wherein the percentages are intended as volumetric fractions.

The features described for one aspect of the invention may be transferred mutatis mutandis to the other aspect of the invention.

The air purifier according to the invention considers in the optimization of the airflow through the pot and to the roots also the matrix in which the plant grows. According to the knowledge of the inventors, it was never considered to optimize the matrix to help the ventilation system to transport air to the roots.

The combination of the particular matrix in the sense of the invention with the humidification thereof and the optimization of the flow also based on the fan velocity and the airflow direction through the fan, also calculated on the basis of the information detected by the sensors, allows to optimize in synergistic form the airflow to the roots and through the matrix. During the operation, the fan draws air from the outside by passing it through the roots of the plant and throwing it out of the control unit. Then, the air drawn from the upper part of the flower pot passes through the roots and the culture matrix and is processed by the microorganisms which live and are generated in the matrix and roots of the plant. This filtered air then passes through the holes of the inner flower pot and leaves the system through the control unit. It is also possible to reverse the air direction through the air purifier.

Embodiment variants of the present invention and further objects and advantages are described hereinafter with reference to the drawings. Embodiment variants of the invention are the object of the dependent claims. The description of preferred embodiment examples of the air purifier and of the culture matrix according to the invention is only given in an exemplary and non-limiting manner.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of a first embodiment variant of an air purifier according to the invention.

FIG. 2 illustrates, in a sectional view, the air purifier according to FIG. 1 in the assembled state with a plant and a culture matrix included; FIG. 3 shows the control unit of the air purifier according to figures 1 and 2 and its components.

FIG. 4 is an exploded view of a second embodiment variant of an air purifier according to the invention.

FIG. 5 illustrates the embodiment variant of FIG. 4 in a sectional view with an inserted plant.

DESCRIPTION OF PREFERRED EMBODIMENT EXAMPLES

FIG. 1 is an exploded view which illustrates an embodiment variant of the air purifier 2 according to the present invention. The air purifier 2 contains: an outer flower pot 4, a perforated inner flower pot 6 with a plurality of holes 7, a collector plate 8 to contain excess water, a gasket 10, a technical or control unit 12, a metal plate 14 and a metal grid 16 and a pair of screws 18.

The inner flower pot 6 must be inserted in the outer flower pot 4, these two pieces are sealed by the gasket 10, positioned on the intersection of the two pieces, or more in detail positioned on an annular protuberance 4a realized along the entire perimeter of the upper edge of the opening 4b receiving the inner flower pot 6, which rests with its upper protruding edge 6a on the gasket 10.

The control unit 12 is inserted in a side hole 4c of the outer flower pot 4 and is locked by two screws 18 inside by means of the metal plate 14 on the inner side and by means of the metal grid 16 on the outer side. The metal grid 16 has both an aesthetic purpose and also a protective purpose.

With reference to FIG. 2, the embodiment variant of the air purifier is shown in a sectional view as including in part, a plant 20, its roots 22, a culture matrix 24 and the control unit 12. Arrows 26, 28, 30 show the airflow passing through the system. The control unit 12 draws the air from the upper part of the plant 20, the flow is represented by the arrows 26.

The drawn airflow passes from the upper parts through the roots 22 and the culture matrix 24 of the system, the flow is represented by the arrows 28.

After passing through the roots 22 and the matrix 24, the air is now filtered. The combination of the matrix and the microorganisms which live in the roots of the plant actively filters the toxic agents in the air. The filtered air is now taken out of the inner flower pot 6 thanks to its holes 7. The flow ends its path by passing through the control unit 12 (arrows 30), the leaving air has been filtered by the system a reversed flow direction is also possible.

FIG. 3 illustrates the control unit 12 and its components. A very important part of the control unit is the fan 32, the fan is responsible for creating an airflow through the system.

Another very important part of this invention is the microcontroller 34, which is responsible for the communication and the operation to determine and communicate different parameters. The sensory unit of this invention is composed of: an inner air quality sensor (AIQ) 36, a temperature sensor 38 and a humidity sensor 40. The AIQ sensor can be a VOC sensor (Volatile Organic Compounds).

This control unit, once connected to electricity, starts working independently. The AIQ sensor 36 combined with the temperature sensor 38 and the humidity sensor 40 communicates with the microcontroller 34 in which algorithms are coded. Different values from these sensors give different combinations of system functionality. The main and very important output is the velocity and activation of the fan 32. This is crucial because it directly influences the intensity of the airflow that passes through the system.

Communication is possible thanks to the Wi-Fi module 42, this module is able to connect to many smart devices, including smartphones, computers, and many others.

The main device which will be able to read the data communicated by the control unit 12 will be a normal smartphone, suitable to read Wi-Fi signals. Data will be displayed on a regular application; users will be able to see the data and manage the basic functionalities of the system: fan 32 operation, connections and more. A ring-shaped gasket 44 helps to seal the control unit 12 in the side hole 4c of the inner flower pot 4. Together with the gasket 10 a controlled airflow is guaranteed through the control unit 12 and soil 24 and roots 22 without losses.

FIG. 4 shows another embodiment variant suitable for the furnishing according to the invention in an exploded view. The air purifier 402 has an outer flower pot 404 and an inner flower pot 406 with holes 407, a gasket 410 which provides a sealed insertion of the inner flower pot 406 in the upper opening 404b of the outer flower pot 404. A control unit 412 (which essentially corresponds to the control unit described with reference to fig. 4) is inserted in the side opening 404c of the outer flower pot 404 and fixed by means of a metal plate 414. The control unit 412 is protected by a metal grid 416. An electric current power supply is indicated with reference number 415. The main difference - apart from slight structural changes - compared to the variant shown in fig. 1 is the partition plate 401 which is placed on a respective support (not shown) inside the inner flower pot 406. The partition plate 401 is provided with two pairs of holes 403 which receive the ends of two cords 405. The partition plate 401 divides the inner flower pot 406 into two chambers (not shown), the lower chamber serves as a water tank and the upper chamber serves to contain a matrix suitable for the plant growth. The cords 405 will be wet with water in the tank and the water will go up the cords to transport water into the matrix. Alternatively, the cords may be replaced by thin tubes, one end of which is immersed in water in the lower chamber, the other end of which ends in the matrix. The partition plate 401 also has a supply pipe 431 which allows the lower chamber to be filled with water from the upper side of the air purifier 402. The supply tube

431 can be closed by a cover 409 which is composed of an upper cover plate 411, a magnet 413 (to activate the Reed contact) and a bottom plate 417 to contain the magnet 413. The three parts are assembled together to form the cover 409. The supply tube 431 may contain a floating indicator 419 which indicates the water level in the tank.

FIG. 5 illustrates the embodiment variant of FIG. 4 in a sectional view with a plant 420 inside. The inner flower pot 406 is housed inside the outer flower pot 404 sealed by the gasket 410. The partition plate 401 divides the inner flower pot 406 into an upper chamber filled with a culture matrix in the sense of the invention 424 and a lower chamber 425 (water tank) filled with water (dashed line) through the supply tube 431 which contains the floating indicator 419 and is closed by a cover 409. A cord 405 transports water from the water reservoir 425 to the culture matrix 424. The dashed arrow 427 shows a possible airflow entering from the upper part of the air purifier 402, passing through the matrix 424 and roots (not shown) leaving the inner flower pot 406 through the holes 407 and passing through the space between the inner and outer flower pot 404, 406 and, finally, coming out from the system through the control unit 412. A reversed flow in the opposite direction is also conceivable.

Various tests have been performed to evaluate the purification power of the air purifier as a function of the fan and of different matrices used. The experiments have been conducted with the Sansevieria Trifasciata and Spathiphyllum "Mauna Loa" plants. The capacities of the system and, in particular, of the matrices to eliminate four main indoor volatile organic compounds, namely isopropyl alcohol, formaldehyde, benzene and limonene were tested. The measurements were carried out indoors.

The use of a fan has the clear effect of lowering the concentrations of the tested VOCs more effectively.

A suitable organic matter containing soil is, e.g., a commercial mixture for pot plants, such as Compo® for green plants. Such soil is composed of black peat, clay and slow release fertilizers.

Various mixtures of organic matter containing soil and granular material were compared as regards the characteristics of compactness and density. The most compact mixtures were the pure granular material or a mixture of 10% (v/v) of granular material and 90% (v/v) of organic matter containing soil. The combination 40% (v/v) granular material and 60% (v/v) organic matter containing soil is however surprisingly the less affected by an applied compaction.

Also, from the porosity and water volumetric content point of view the combination 40% (v/v) granular material and 60% (v/v) organic matter containing soil is the most advantageous, which is an unexpected result given the high organic matter containing soil content which tends to be compact.

The choice of the combination above was then confirmed by the purifying properties determined for four volatile organic compounds. For isopropyl alcohol, reductions of about 30% after one hour and more than 80% after 24 hours were observed compared to the initial amounts present in the air. The reductions obtainable for formaldehyde amounted to about 50- 55% after an hour, while after 24 hours they were more than 70%. Lowering the content in benzene or limonene was much less satisfactory after one hour (benzene: < 5%; limonene: 0%), while after 24 hours there was a reduction of about 30% for benzene and about 20% for limonene.

A strong positive influence on the reduction of toxic agents in the air has increased the fan velocity and the reversal of the airflow direction through the purifier. The addition of charcoal also improves the purifying effect of the matrix. Unexpectedly, a content of 20% (v/v) in the matrix has a better effect than a content of 30% (v/v). Suitable charcoals are, e.g., 4 mm non regenerated cylindrical pellets. A suitable organic matter containing soil may include black peat, clay and slow release manure and has a pH (H ₂ 0) between 6.0 and 7.0.

The best matrix is the one identified in the tenth claim which combines in a very satisfactory way the plant requests to the chemical and agronomic characteristics, suitable characteristics of compactness, density and porosity and the ability to eliminate volatile organic compounds. The invention has been presented and described in connection with various embodiment variants. For those skilled in the art and familiar with the subject it is clear that changes and variations that may occur are not excluded from the concept of the invention and from the scope of protection as defined by the appended claims.