FR3058908B1 - AIR FILTER FOR MOTOR VEHICLE - Google Patents

Abstract

The present invention relates to an air filter (1) for a motor vehicle (V), said area filter (1) comprising a plurality of layers (C) comprising at least two layers (CA1, CAt2) of an adsorbent material, of which at least one layer (CAt2) of the adsorbent material is treated so as to selectively filter a gas.

Description

The present invention relates to an air filter for a motor vehicle.

The invention finds a particular, but not limiting, application in air filters for fuel cells for a motor vehicle.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

A fuel cell for a motor vehicle is adapted to generate electrical energy which will power the engine of said motor vehicle. A fuel cell includes two electrodes, a cathode and an anode. The reduction of hydrogen on the cathode and the oxidation of oxygen on the cathode results in the production of electrical voltage, water and heat.

A disadvantage of this state of the art is that air pollution damages the electrodes of the fuel cell. In particular, polluting gases such as sulfur dioxide (SO2) or nitrogen oxide (NOX) are harmful to the electrodes since they respectively produce sulfuric acid (H2SO4) and nitric acid (HNO3 ) which eat away at said electrodes. Consequently, the fuel cell has a limited lifespan due to said air pollution. Its lifespan can be reduced to a few weeks or even a few days in the case of air pollution is very important.

In this context, the present invention aims to solve the aforementioned drawback.

GENERAL DESCRIPTION OF THE INVENTION

To this end, the invention provides an air filter for a motor vehicle, according to which said air filter comprises a plurality of layers comprising at least two layers of an adsorbent material, at least one layer of the adsorbent material of which is treated to selectively filter a gas. Thus, thanks to the selective filtration of one or more gases harmful to a fuel cell, the life of said fuel cell is increased.

According to non-limiting embodiments, the air filter for a motor vehicle can also include one or more additional characteristics among the following:

According to a nonlimiting embodiment, said at least one layer of the treated adsorbent material has undergone a physicochemical treatment. This makes it possible to modify the surface state of the adsorbent material A. The latter will thus filter a given gas.

According to a nonlimiting embodiment, the physicochemical treatment is the addition of a catalyst or of an impregnation. The addition of a catalyst makes it possible to obtain a catalyzed adsorbent material.

According to a nonlimiting embodiment, said filtered gas is:

- sulfur dioxide; or

- at least one nitrogen oxide; or

- ammonia.

These are the gases that are most harmful, especially for a fuel cell.

According to a nonlimiting embodiment, the adsorbent material is activated carbon or a zeolite. Activated carbon is inexpensive and common.

According to a nonlimiting embodiment, said air filter comprises at least three layers of an adsorbent material, of which:

- a first layer of the adsorbent material;

a second layer of the adsorbent material treated so as to selectively filter a gas;

- At least a third layer of the adsorbent material treated so as to selectively filter a gas.

With two layers of treated adsorbent material, more gas is filtered.

According to a nonlimiting embodiment, the gas filtered by the second layer of the treated adsorbent material and the gas filtered by said at least one third layer of the treated adsorbent material are different.

This makes it possible to filter several harmful gases, harmful in particular for the fuel cell.

According to a nonlimiting embodiment, said air filter further comprises at least one nonwoven layer. It can serve as a support for depositing the layer of adsorbent material and also makes it possible to filter the dust.

According to a nonlimiting embodiment, the nonwoven layer comprises fibers of polyester and / or polypropylene and / or polyamide. These are commonly used materials.

According to a nonlimiting embodiment, said at least one nonwoven layer is a flexible nonwoven filtration layer. It follows the rigid layer and allows pleating in the event that the layers are pleated.

According to a nonlimiting embodiment, the flexible nonwoven filtration layer is:

- a high efficiency layer; or

- a water jet binding layer;

- a needled layer.

The high efficiency layer is a layer with a tight weave which effectively blocks fine particles.

According to a nonlimiting embodiment, said at least one nonwoven layer is a rigid nonwoven layer.

This rigid nonwoven layer is a structural layer which makes it possible to stiffen the air filter and to hold all of the layers together.

According to a nonlimiting embodiment, the air filter further comprises pleating of all of the layers. This makes it possible to multiply the filtration surface over a small space.

According to a nonlimiting embodiment, at least one layer of the adsorbent material is in the form of fabric. This makes it possible to remove a nonwoven layer serving as a support for the adsorbent material. Thus, the air filter is less tall and is therefore more compact.

According to a nonlimiting embodiment, said layer of adsorbent material is placed closer to an air inlet of the motor vehicle than said at least one layer of treated adsorbent material. This absorbs the largest particles of gas and then the finest.

According to a nonlimiting embodiment, said air filter comprises at least one filtering medium comprising at least one layer of adsorbent material.

According to a nonlimiting embodiment, said air filter comprises a plurality of filter media, each filter media comprising at least one layer of adsorbent material. This makes it easier to fold the different layers of the air filter and to have a larger developed filtration area than in the case of a single filter medium.

According to a nonlimiting embodiment, said at least one layer of adsorbent material is in the form of fabric or said filter medium comprises a nonwoven layer which serves as a support for said at least one layer of adsorbent material.

According to a nonlimiting embodiment, at least one filtering medium further comprises a rigid nonwoven layer. This rigid nonwoven layer is a structural layer which makes it possible to stiffen the filtering medium and to hold all the layers of the filtering medium together.

According to a nonlimiting embodiment, said air filter comprises:

- a first filtering medium comprising:

- said layer of adsorbent material;

- a second filtering medium comprising:

- Said at least one layer of the adsorbent material treated so as to selectively filter a gas.

According to a nonlimiting embodiment:

- Said layer of adsorbent material is in the form of fabric or said first filtering medium further comprises a nonwoven layer which serves as a support for said layer of adsorbent material;

- Said at least one layer of the treated adsorbent material is in the form of fabric or said second filtering medium further comprises a nonwoven layer which serves as a support for said at least one layer of the treated adsorbent material.

According to a nonlimiting embodiment:

- Said first filtering medium further comprises a rigid nonwoven layer; and or

- Said second filtering medium further comprises a rigid nonwoven layer.

According to a nonlimiting embodiment, said air filter comprises:

- a first filtering medium comprising:

- Said first layer of the adsorbent material;

- a second filtering medium comprising:

- Said second layer of the adsorbent material treated so as to selectively filter a gas;

- at least a third filtering medium comprising:

- Said at least a third layer of the adsorbent material treated so as to selectively filter a gas.

According to a nonlimiting embodiment:

- Said first layer of the adsorbent material is in the form of fabric or said first filtering medium further comprises a nonwoven layer which serves as a support for said first layer of adsorbent material;

- Said second layer of the treated adsorbent material is in the form of fabric or said second filtering medium further comprises a nonwoven layer which serves as a support for said second layer of the treated adsorbent material;

- Said at least a third layer of the treated adsorbent material is in the form of fabric or said at least a third filter medium further comprises a nonwoven layer which serves as a support for said third layer of the treated adsorbent material.

According to a nonlimiting embodiment:

- Said first filtering medium further comprises a rigid nonwoven layer; and or

- Said second filter medium further comprises a rigid nonwoven layer; and or

- Said at least a third filter medium further comprises a rigid nonwoven layer.

It is also proposed a fuel cell comprising an air filter according to any one of the preceding characteristics.

According to a nonlimiting embodiment, said fuel cell receives an incoming air flow as input, and said air filter is positioned upstream of the combustion cell so as to process the incoming air flow.

PATENT DESCRIPTION OF THE FIGURES

The invention and its various applications will be better understood on reading the description which follows and on examining the figures which accompany it:

- Figure 1 schematically shows an air filter for a motor vehicle according to a first non-limiting embodiment of the invention, said air filter comprising a plurality of layers including at least two layers of adsorbent material;

- Figure 2 schematically shows an air filter for a motor vehicle according to a second non-limiting embodiment of the invention, said air filter comprising a plurality of layers including at least three layers of adsorbent material;

- Figure 3a schematically shows an air filter for a motor vehicle according to a first non-limiting variant of a third non-limiting embodiment of the invention, said air filter comprising a layer of adsorbent material in the form of fabric;

- Figure 3b schematically shows an air filter for a motor vehicle according to a second non-limiting variant of a third non-limiting embodiment of the invention, said air filter comprising a layer of adsorbent material in the form of fabric;

- Figure 3c schematically shows an air filter for a motor vehicle according to a third non-limiting variant of a third non-limiting embodiment of the invention, said air filter comprising a layer of adsorbent material in the form of fabric;

- Figure 3d schematically shows an air filter for a motor vehicle according to a fourth non-limiting variant of a third non-limiting embodiment of the invention, said air filter comprising two layers of adsorbent material in the form of fabric;

- Figure 3e schematically shows an air filter for a motor vehicle according to a fifth non-limiting variant of a third non-limiting embodiment of the invention, said air filter comprising two layers of adsorbent material in the form of fabric;

- Figure 3f schematically shows an air filter for a motor vehicle according to a sixth non-limiting variant of a third non-limiting embodiment of the invention, said air filter comprising three layers of adsorbent material in the form of fabric;

- Figure 3g schematically shows an air filter for a motor vehicle according to a sixth non-limiting variant of a third non-limiting embodiment of the invention, said air filter comprising three layers of adsorbent material in the form of fabric;

- Figure 4 schematically shows an air filter of Figure 2, said air filter comprising a filter medium comprising said plurality of layers;

- Figure 5a schematically shows an air filter of Figure 1, said air filter comprising two filter media each comprising a portion of said plurality of layers;

- Figure 5b schematically shows an air filter of Figure 1, said air filter comprising two filter media each comprising a portion of said plurality of layers, said filter media being bonded together;

- Figure 5c schematically shows an air filter of Figure 2, said air filter comprising two filter media each comprising a portion of said plurality of layers;

- Figure 6a schematically shows an air filter of Figure 2, said air filter comprising three filter media each comprising a portion of said plurality of layers;

- Figure 6b schematically shows an air filter of Figure 3g, said air filter comprising three filter media each comprising a portion of said plurality of layers including three layers in the form of fabric;

- Figure 7 shows a perspective view of a filter media of the air filter of Figure 3g without a framing strip, according to a non-limiting embodiment;

- Figure 8 shows a perspective view of the filter medium of Figure 7 with two framing strips;

- Figure 9 is a sectional zoom on a part of the filter medium of Figure 7, said part comprising said plurality of layers;

- Figure 10 shows the air filter of Figure 7 and a sectional view of the filter media of said air filter;

- Figure 11 shows the air filter of Figure 5a, 5b or 5c and a sectional view of the filter media of said air filter; and

- Figure 12 shows the air filter of Figures 6a or 6b and a sectional view of the filter media of said air filter.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Identical elements, by structure or by function, appearing in different figures keep, unless otherwise specified, the same references.

The air filter 1 for a motor vehicle V is described with reference to FIGS. 1 to 12.

By motor vehicle is meant any type of motor vehicle.

In a nonlimiting embodiment, the air filter 1 is suitable for filtering the air at the inlet of a fuel cell (not shown). Said fuel cell receives an air flow at input, and said air filter is positioned at the input of an incoming air flow F (illustrated in FIG. 1), and said air filter 1 is positioned upstream of the combustion cell so as to process the incoming air flow F.

The fuel cell is taken as an example of nonlimiting application in the following description.

To produce electrical energy, a fuel cell requires a reducing fuel and an oxidant. In a nonlimiting example, the reducing fuel is hydrogen and the oxidant is oxygen. A fuel cell includes two electrodes, namely a cathode and an anode. The reduction on the cathode of hydrogen and the oxidation on the anode of oxygen leads to the production of electric voltage, water and heat.

Since a fuel cell is known to those skilled in the art, it is not described in more detail here.

The air filter 1 comprises a plurality of layers C comprising at least two layers CA1, CAt2 of an adsorbent material A, at least one layer CAt2 of the adsorbent material A is treated so as to filter a gas G selectively.

Note that a layer C is also called a layer.

In the following description, a layer of the adsorbent material A treated so as to filter a gas G selectively will also be called the layer of the adsorbent material treated or layer treated. In addition, a layer CA1 of the adsorbent material A will also be called layer CA1 or untreated layer CA1. By untreated layer is meant that there is no physico-chemical treatment.

A layer CA1 is suitable for filtering a gas Z such as in non-limiting examples of butene or toluene. These gases are in the air.

A treated layer CAt2 is suitable for filtering most of a given gas G. Of course, the same CAt2 treated layer can also filter other gas (s), if necessary, but in a smaller proportion.

The selection of the gas G to be filtered is carried out by means of the treatment which said at least one layer CAt2 has undergone as described below.

The gas G filtered by said at least one treated layer CAt2 comprises particles finer than those of the gas Z filtered by the layer CA1. The air filter 1 thus filters larger particles and finer particles.

The motor vehicle V comprises an air inlet (not shown) through which an air flow F can enter and flow towards the fuel cell in the example of non-limiting application taken. This provides oxygen for the fuel cell that needs it to function.

In a nonlimiting embodiment, the layer CA1 is placed closer to the air inlet than said at least one layer treated CAt2 as illustrated in FIG. 1. This makes it possible to filter the largest polluting particles first. , then the finest. Thus, the air filter 1 comprises layers C which first filter the largest particles and then the finest particles last. In the case where the air filter 1 comprises several treated layers, the treated layer furthest from the layer CA1 is suitable for filtering the finest particles.

Thus, by first filtering the gases with large particles, one avoids saturating said at least one layer treated CAt2 with the gases Z of larger particles (such as butane or toluene) so as to better capture the determined gases G which have smaller particles. In a nonlimiting example, the large particles have a diameter greater than 2.5 μιτι (micrometers) and the small particles have a diameter less than 2.5 pm.

Said at least one layer of the adsorbent material treated CAt2 has undergone a physico-chemical treatment.

In a first nonlimiting embodiment, the physicochemical treatment is an addition of a catalyst so as to obtain a catalyzed adsorbent A material.

In a second nonlimiting embodiment, the physicochemical treatment is an impregnation. Note that an impregnation is also called doping.

Thanks to the physico-chemical treatment, the surface state of the adsorbent material A is modified to promote the selective adsorption of a given gas G.

The treatment of an adsorbent material A by catalysis, by impregnation or by doping of chemicals makes it possible to physically condition said adsorbent material A so that it is selective for filtering a certain gas G.

Catalysis, impregnation or doping being well known to those skilled in the art, they are not described here.

In nonlimiting embodiments, the gas (s) G selectively filtered by the air filter 1 is:

- sulfur dioxide SO2; or

- at least one NOX nitrogen oxide; or

- NH3 ammonia.

In the following description, for the sake of brevity, the abbreviations SO2, NOX, NH3 will be used.

SO2 and NOX are gases found in particular in the exhaust gases of motor vehicles. NOX is found in particular in exhaust gases from diesel vehicles.

NH3 is a gas that is found in the air due to the chemical industries for example.

To produce electrical energy, a fuel cell needs oxygen 02 and hydrogen H2.

With regard to SO2, it reacts with oxygen so as to give sulfur trioxide SO3 which itself reacts with water H2O to give sulfuric acid H2SO4.

The synthesis of sulfuric acid H2SO4 which occurs around the fuel cell electrodes from sulfur dioxide SO2 thus includes the following chemical reactions:

2SO2 + 02 2SO3

SO3 + H2O H2SO4

Thus, SO2 is particularly harmful to the electrodes of a fuel cell, because it produces sulfuric acid H2SO4 which eats up said electrodes (more particularly that of platinum Pt).

NOX includes nitrogen monoxide NO and nitrogen dioxide NO2.

Nitrogen monoxide NO reacts with oxygen 02 to give nitrogen dioxide N02 and nitrogen dioxide N02 reacts with water H20 to give nitric acid HNO3.

The synthesis of the nitric acid HN03 which occurs around the electrodes of the fuel cell from nitrogen oxides NOX thus comprises the following chemical reactions:

2N0 + 502 -> 2NO2

3NO2 + H2O -> 2HNO3 + NO

Thus, NOX are particularly harmful to the electrodes of a fuel cell, because they produce nitric acid HNO3 which eats away at said electrodes.

Regarding NH3, it reacts with oxygen 02 to give nitrogen monoxide NO. Oxidation of NO nitrogen monoxide gives NO2 nitrogen dioxide. Nitrogen dioxide NO2 reacts with oxygen 02 to give nitrogen peroxide N2O4. The latter is adsorbed in H2O water which gives nitric acid HNO3.

The synthesis of nitric acid H N 03 which occurs around the electrodes of the fuel cell from ammonia NH3 thus comprises the following chemical reactions: 4NH3 + 502 -> 4N0 + 6H2O

2N0 + 502 -> 2NO2

2NO2 + 02 -> N2O4

3N2O4 + 2H2O -> 4HNO3 + 2NO

NH3 is therefore particularly harmful to the electrodes of a fuel cell, since they produce nitric acid HN03 which eats away at said electrodes.

• Matérjau.adsorbarit A

The adsorbent material A is described in detail below.

In a first non-limiting embodiment, the adsorbent material A is activated carbon.

Activated carbon filters the surrounding gases (from the motor vehicle in the non-limiting example taken) and the particles in the surrounding air, such as dust particles.

In nonlimiting embodiments, the activated carbon can be in the form of powder, grains, extrudates, or fabric.

In a nonlimiting embodiment, when it is in the form of a grain, the activated carbon comprises grains of size 30 to 50 μm in diameter.

In a nonlimiting embodiment, when it is in the form of a fabric, the activated carbon comprises a basis weight of 50 to 500 g / m ² .

In order to obtain better bonding of the activated carbon on the nonwoven layer Nt (described below) on which it is deposited, in a nonlimiting embodiment, the activated carbon comprises an adhesive (not illustrated) mixed with the grains. This makes it possible to make a good bond between said activated carbon and the adjacent nonwoven layer Nt. Thus, in a nonlimiting example, for

100 grams, there are 92 grams of activated carbon grains and 8 grams of added glue. In a nonlimiting embodiment, for 100 grams of activated carbon, there is at most 25 grams of glue. In a non-limiting variant, there are between 5 and 15 grams of glue per 100 grams of activated carbon.

In a nonlimiting example, the adhesive is a polyolefin or polyethylene adhesive.

Activated carbon is used as a catalytic support for metal complexes so as to oxidize gases such as SO2, NOX, NH3 and thus promote their adsorption. This is made possible by a physico-chemical treatment on the activated carbon which is the addition of a catalyst giving rise to an activated carbon called "catalyzed".

In nonlimiting embodiments, the complexes are:

- Metals such as platinum Pt or titanium Ti in nonlimiting examples with associated L ligands; or

- metal oxides such as copper Cu, iron Fe, Nickel Ni in nonlimiting examples with associated L ligands.

In nonlimiting examples, complexes thus include:

- a metal cation M = Cu and a ligand L = HCL. The gas is thus oxidized by the Cu / A-HCL complex.

- a metal cation M = Ni and a ligand L = HNO3. The gas is thus oxidized by the NÎ / A-HNO3 complex.

The result of catalyzed activated carbon gives:

- H2SO4 in the liquid state, from SO2;

- HNO3 in the liquid state, from NOX;

- NH3 + from NH3.

Note that in the liquid state, H2SO4 and HNO3 are retained by the activated carbon which prevents them from reaching the electrodes. Thanks to the addition of a catalyst, a reduction of SO2, NOX, NH3.

In the case of a physico-chemical treatment which is an impregnation, the activated carbon is impregnated with:

- urea; or

- melamine; or

- sodium hydroxide NaOH; or

- potassium hydroxide KOH; or

- via hydrogen peroxide; or

- nitric acid HNO3; or

- acids such as hydrochloric acid HCL, or sulfuric acid H2SO4, or phosphoric acid H3PO4.

Thanks to this impregnation, a reduction in SO2, NOX and NH3 is obtained.

In a second nonlimiting embodiment, the adsorbent material A is a zeolite. In a nonlimiting embodiment, the zeolite is part of the Chabazite family. In a nonlimiting variant, the zeolite is a Ferrierite. In another nonlimiting embodiment, the zeolite is an iron doped zeolite.

The same catalysts can be added for a zeolite as those of activated carbon to obtain a catalyzed zeolite.

A zeolite can be doped in the same way as the activated carbon has been impregnated.

In a nonlimiting embodiment, the adsorbent material A is in the form of fabric. So you can have activated carbon fabric.

In a nonlimiting embodiment, the fabric of adsorbent material A replaces a layer of adsorbent material A (treated or not) combined with an adjacent nonwoven filter layer Nt (described below) on which said layer of adsorbent material A rests . This makes it possible to reduce the height of the air filter 1 and thus to have a more compact air filter if necessary. This layer of nonwoven material Nt which is removed is a flexible nonwoven layer Nts or a rigid nonwoven layer Ntr.

• LayersC

The layers C of the air filter are described in detail below.

The layers C are linked together by means of an adhesive.

The adhesive is deposited on each nonwoven layer Nt on which a layer of the adsorbent material A will rest. Then, the layers of adsorbent material A (treated or not) are deposited on a nonwoven layer Nt.

A final flexible nonwoven layer Nts is glued and then deposited on the last layer of adsorbent material A.

Finally, all of the layers C are assembled by rolling. Note that the bonding and assembly process being known to those skilled in the art, it is not described here.

In nonlimiting embodiments, the adhesive comprises one or more of the following compounds:

- Polyolefin (po), this compound having the advantage of being economical;

- Polyamide (pa); and or

- Crosslinked polyurethane (pure).

In a first nonlimiting embodiment, the glue is deposited on a layer C in a veil of glue. It covers the entire surface with a layer C.

In a second nonlimiting embodiment, the glue is fiberized. The use of a fiberized glue makes it possible to deposit glue on at least one layer C so as to have a layer C with regions covered with glue and smaller regions without glue. These smaller regions are areas through which an air flow can pass. Thus, the air flow is not stopped by the adhesive and the clogging capacity of the air filter 1 is greater than with the use of a veil of adhesive, which increases the life of the filter. air 1. Note that the clogging capacity is the capacity of the air filter 1 to accumulate the particles of gases.

In a nonlimiting embodiment, said air filter 1 comprises at least one nonwoven layer Nt.

By “nonwoven”, it is meant that the layer C comprises fibers held together amorphously, that is to say in no particular order.

In a nonlimiting embodiment, the nonwoven layer Nt comprises fibers made of PES ("Polyester") and / or PP ("Polypropylene") and / or PA (Polyamide).

It will be noted that there may be different functions integrated beforehand in the nonwoven layers Nt of the air filter 1 before their assembly. Thus, in a nonlimiting embodiment, the nonwoven layers Nt may have been previously impregnated with an antiallergenic chemical compound.

In a nonlimiting embodiment, the nonwoven layers Nt may also have been previously impregnated with a treatment against VOCs (Volatile Organic Compound) such as formaldehydes.

An Nt nonwoven layer can be adapted to filter the dust.

In a nonlimiting embodiment, the nonwoven layer Nt serves as a support for a layer of the adsorbent material A. Indeed, for example it allows a dusting of a layer of activated carbon on said nonwoven layer Nt or also a dusting a layer of zeolite on said nonwoven layer Nt.

The nonwoven layer Nt is described according to two embodiments below.

o Layer, of fjItration.non.woven, .souple. nts

In a first nonlimiting embodiment, said at least one nonwoven layer Nt is a flexible nonwoven filtration layer Nts. In nonlimiting variant embodiments, the flexible nonwoven filtration layer Nts is:

- a high efficiency layer; or

- a water jet binding layer; or

- a needled layer.

A flexible, high-efficiency nonwoven filtration layer is obtained by the meltblown technique, and known in English as “meltblown”. It is a layer which contains microfibers obtained by hot air.

This high efficiency layer has smaller spaces than a conventional nonwoven filter layer. This allows smaller particles (especially fine particles) to be filtered than conventional flexible or rigid nonwoven filter layers. In the following description, the flexible high-efficiency nonwoven filtration layer Mlb is also called the high efficiency layer Mlb. In a nonlimiting example, the fine particles have a diameter of less than 2.5 μιτι (micrometers). A so-called "water jet binding" layer comprises fibers obtained by the water jet entanglement technique, also called the hydroliage technique, and called in English "spunlace".

A layer called "needle punch" comprises fibers obtained by needle punching, called in English "needlepunch".

These techniques for manufacturing a flexible Nts nonwoven layer being known to those skilled in the art, they are not described in detail here.

In a nonlimiting embodiment, the flexible nonwoven layer Nts serves as a support for a layer of the adsorbent material A and / or to filter the dust. In a nonlimiting variant, it serves as a support for a layer of the adsorbent material CAt2, CAt3 treated.

o Layer, of. fiItratig.n.not.woven, rigid. Ntr

In a second nonlimiting embodiment, said at least one nonwoven layer Nt is a rigid nonwoven filtration layer Ntr.

This rigid nonwoven filtration layer Ntr is a structural layer which makes it possible to hold all of the layers C of the filter medium MF together. In particular, it maintains the layers together after pleating (described later). It thus avoids dislocation of said layers C. [It will be noted that a rigid nonwoven filtration layer Ntr has a porosity greater than that of a flexible nonwoven filtration layer Nts.

In nonlimiting embodiments, a rigid nonwoven filtration layer Ntr is:

- a layer whose threads are obtained by cold air, called in English (“Spunbound”);

- a layer obtained with a flexible nonwoven Nts filtration layer combined with a stiffening adjuvant. In a nonlimiting example, the stiffening adjuvant is a resin. For example, this applies with the so-called "spunlace" layer or the so-called "needled" layer.

a layer obtained with a flexible nonwoven filtration layer Nts, the fibers of which have been assembled hot and then hot pressed. For example this applies with the so-called "spunlace" layer.

As will be seen later, these two embodiments can be combined, namely the air filter 1 can comprise at least one flexible nonwoven filtration layer Nts and at least one rigid nonwoven filtration layer Ntr.

The air filter 1 and its different layers C is described according to different non-limiting embodiments illustrated in Figures 1 to 6b.

In a nonlimiting embodiment, the rigid nonwoven layer Nt serves as a support for a layer of the adsorbent material A and / or to filter the dust. In a non-limiting variant, it serves as a support for a layer of the adsorbent material CA1.

ο Ρ [θ.Τ) θΓ..Τθΰθ ^ ..OOD.Jiîr.itatjf

According to a first nonlimiting embodiment illustrated in FIG. 1, the air filter 1 comprises two layers of adsorbent material A, of which:

- a first layer CA1 of an adsorbent material A, called the first layer CA1;

a second layer CAt2 of the adsorbent material A treated, called the second layer CAt2 or layer treated CAt2.

According to a nonlimiting embodiment, the air filter 1 also comprises a nonwoven layer Nt.

According to a first nonlimiting variant, the nonwoven layer Nt is a flexible nonwoven layer Nts.

According to a second nonlimiting variant, the nonwoven layer Nt is a rigid nonwoven layer Ntr. This rigid nonwoven layer Ntr is adjacent to the first layer CA1 of the adsorbent material A. makes it possible to stiffen all of the layers C.

The first variant and the second variant can be combined together.

Thus, as illustrated in FIG. 1, the layers C of the air filter 1 are ordered as follows:

- the rigid nonwoven layer Ntr which serves as a support for the first layer CA1 and for filtering dust;

- the first layer CA1;

- a flexible nonwoven layer Nts which serves as a support for the layer of adsorbent material A treated with CAt2 and for filtering dust. It is arranged between the first layer Ca1 and the second layer CAt2;

- the second CAt2 layer;

- a flexible nonwoven layer Nts which is used to filter dust. It does not support any layer of the adsorbent material A. It is placed on the second layer CAt2.

According to a nonlimiting embodiment (not illustrated), at least one layer of the adsorbent material A is in the form of fabric. In this case, it does not need an Nt nonwoven layer which serves as a support. It does not rest on any non woven Nt layer.

Thus, we can have:

a rigid nonwoven layer Ntr, the first layer CA1 of adsorbent material A in the form of fabric, a flexible nonwoven layer Nts which serves as a support for the second layer CAt2, and the second layer CAt2 treated; or

a rigid nonwoven layer Ntr, the first layer CA1 and the second layer CAt2 treated in the form of fabric and the first layer CA1; or

a rigid nonwoven layer Ntr, the first layer CA1 of adsorbent material A in the form of fabric and the second layer CAt2 treated in the form of fabric.

In the three cases above, there can be at least one additional flexible nonwoven layer, placed on the second layer CAt2 or at any other place in the air filter 1 to filter the dust.

According to a nonlimiting embodiment, the second layer CAt2 treated makes it possible to filter a gas G which is SO2, the latter being the most harmful for the electrodes of the fuel cell.

Of course, according to other nonlimiting embodiments, the second layer CAt2 treated makes it possible to filter a gas G which are NOX or NH3.

o Second mode.deiéalis ^^

According to a second nonlimiting embodiment, the air filter 1 comprises at least three layers of an adsorbent material A of which at least two layers are treated CAt2, CAt3.

According to a nonlimiting alternative embodiment illustrated in FIGS. 2 to 3g, the air filter 1 comprises three layers of adsorbent material A, of which:

- a first layer CA1 of an adsorbent material A, called the first layer CA1;

- A second layer CAt2 of the adsorbent material A treated, called second layer CAt2 treated or second layer CAt2;

a third layer CAt3 of the adsorbent material A treated, called the third layer CAt3 treated or third layer CAt3.

According to another non-limiting variant embodiment not illustrated, the air filter 1 comprises more than three layers of adsorbent material A.

According to a nonlimiting embodiment, the second layer CAt2 treated makes it possible to filter a gas G1 which is SO2, the latter being the most harmful for the electrodes of the fuel cell.

Of course, according to other nonlimiting embodiments, the second layer CAt2 treated makes it possible to filter a gas G1 which is one or more NOX or NH3.

According to nonlimiting embodiments, the third layer CAt3 treated makes it possible to filter a gas G2 which is one or more NOX or NH3.

Of course, in another nonlimiting embodiment, the third layer CAt3 treated makes it possible to filter a gas G2 which is SO2.

In a nonlimiting embodiment, the gases G1, G2 filtered respectively by the second layer CAt2 and by the third layer CAt3 are different. Thus, the air filter 1 makes it possible to filter several gases which are very polluting and very harmful in particular for a fuel cell. According to a nonlimiting embodiment, the air filter 1 also comprises at least one nonwoven layer Nt.

In a first non-limiting variant, said nonwoven layer Nt is a flexible nonwoven layer Nts.

The flexible nonwoven layer Nts can serve as a support for the layer of adsorbent material A and / or to filter dust. In fact, for example, it allows a dusting of a layer of activated carbon on said flexible nonwoven layer Nts or else a dusting of a layer of zeolite on said flexible nonwoven layer Nts.

It may not serve as a support and only filter dust.

In a second non-limiting variant, said nonwoven layer Nt is a rigid nonwoven layer Ntr. It makes it possible to stiffen all of the layers C. It can also serve as a support for a layer of the adsorbent material A.

The first variant and the second variant can be combined together.

Thus, as illustrated in FIG. 2, the layers C of the air filter 1 are ordered as follows:

- the rigid nonwoven layer Ntr. It serves as a support for the first layer CA1 and for filtering dust;

- the first layer CA1;

- a flexible nonwoven layer Nts (disposed above the layer CA1). It serves as a support for the second CAt2 layer and for filtering dust;

- the second CAt2 layer;

- a flexible nonwoven layer Nts (disposed above the CAt2 layer). It serves as a support for the third CAt3 layer and to filter dust;

- the third CAt3 layer;

- a flexible nonwoven layer Nts (placed above the layer

CAT3). It is used to filter dust and does not support any layer of adsorbent material A.

It will be noted that the flexible nonwoven layer Nts disposed above the third layer CAt3 serves to hold the adsorbent material A of this third layer CAt3 in place (in the case where the latter is not in the form of fabric).

Each layer of the adsorbent material A is sandwiched between nonwoven layers Nt which makes it possible to keep said adsorbent material A in place.

According to a nonlimiting embodiment, at least one layer of the adsorbent material A is in the form of fabric. In this case, it is not necessary to have an adjacent nonwoven layer which serves as a support. Thus, we can have the following variants:

1 st variant illustrated in FIG. 3a:

- a rigid nonwoven layer Ntr;

- The first layer CA1 of adsorbent material A;

- a flexible nonwoven layer Nts (disposed above the first layer CA1);

- the second CAt2 layer treated;

- the third CAt3 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- a flexible nonwoven layer Nts (disposed above the third layer CAt3).

Note that it is also possible not to have a flexible nonwoven layer Nts above the third layer CAt3.

• 2nd variant illustrated in Figure 3b:

- a rigid nonwoven layer Ntr;

- The first layer CA1 of adsorbent material A;

- the second CAt2 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- a flexible nonwoven layer Nts (disposed above the second layer CAt2);

- the third CAt3 layer treated;

- a flexible nonwoven layer Nts (disposed above the third layer CAt3).

It will be noted that the flexible nonwoven layer Nts disposed above the third layer CAt3 serves to hold the adsorbent material A of this third layer CAt3 in place.

• 3rd variant illustrated in FIG. 3c:

- a rigid nonwoven layer Ntr;

- the first layer CA1 in the form of fabric. In this case, there is no non-woven Nt layer which serves as a support;

- a flexible nonwoven layer Nts (disposed above the first layer CA1);

- the second CAt2 layer treated;

- a flexible nonwoven layer Nts (disposed above the second layer CAt2);

- the third CAt3 layer treated;

- a flexible nonwoven layer Nts (disposed above the third layer CAt3).

It will be noted that the flexible nonwoven layer Nts disposed above the third layer CAt3 serves to hold the adsorbent material A of this third layer CAt3 in place.

• 4th variant illustrated in Figure 3d:

- a rigid nonwoven layer Ntr;

- The first layer CA1 of adsorbent material A;

- the second CAt2 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- the third CAt3 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- a flexible nonwoven layer Nts (disposed above the third layer CAt3).

It will be noted that in this variant, if the two layers CAt3 and CAt2 in the form of fabric make it possible to stiffen the air filter 1, it is possible in another nonlimiting embodiment not to have a rigid nonwoven layer Ntr.

Note that it is also possible not to have a flexible nonwoven layer Nts above the third layer CAt3.

• 5th variant illustrated in Figure 3e:

- a rigid nonwoven layer Ntr;

- the first layer CA1 treated in the form of fabric. In this case, there is no non-woven Nt layer which serves as a support;

- the second CAt2 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- a flexible nonwoven layer Nts (disposed above the second layer CAt2);

- the third layer CAt3 of adsorbent material A;

- a flexible nonwoven layer Nts (disposed above the third layer CAt3).

It will be noted that in this variant, if the two layers CA1 and CAt2 in the form of fabric make it possible to stiffen the air filter 1, it is possible in another non-limiting embodiment to have no rigid nonwoven layer Ntr.

It will be noted that the flexible nonwoven layer Nts disposed above the third layer CAt3 serves to hold the adsorbent material A of this third layer CAt3 in place.

• 6th variant illustrated in Figure 3f:

- a rigid nonwoven layer Ntr;

- the first layer CA1 treated in the form of fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- the second CAt2 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- the third CAt3 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- a flexible nonwoven layer Nts (disposed above the third layer CAt3).

Note that it is also possible not to have a flexible nonwoven layer Nts above the third layer CAt3.

• 7th variant illustrated in Figure 3g:

- the first layer CA1 treated in the form of fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- the second CAt2 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- the third CAt3 layer treated as fabric. In this case, there is no flexible nonwoven layer Nts which serves as a support;

- a flexible nonwoven layer Nts (disposed above the third layer CAt3).

Note that in this variant, there is no rigid nonwoven layer Ntr. Indeed, the three layers CA1, CAt2, CAt3 in the form of fabric are sufficient to stiffen the air filter 1.

Note that it is also possible not to have a flexible nonwoven layer Nts above the third layer CAt3. But in this case, we do not filter the dust.

• Filter media

In a nonlimiting embodiment, the air filter 1 comprises at least one filtering medium MF1, MF2, MF3 comprising at least one layer CA1, CAt2, CAt3 of adsorbent material A.

The air filter 1 thus comprises one or more filter media.

Different embodiments of the air filter 1 with filter medium (s) are described below.

o A filtering media_MF1

According to a first nonlimiting embodiment, the air filter 1 comprises a filter medium MF1.

The filter medium MF1 comprises all of the layers C of the air filter 1. Thus, according to a nonlimiting embodiment illustrated in FIG. 4, the filter medium MF1 comprises the layers of the example of FIG. 2, namely:

- the rigid nonwoven layer Ntr on which the first layer CA1 rests. The rigid nonwoven layer Ntr thus serves as a support;

- the first layer CA1;

- a flexible nonwoven layer Nts on which the second layer CAt2 rests. The flexible nonwoven layer Nts thus serves as a support;

- the second CAt2 layer;

- a flexible nonwoven layer Nts on which the third layer CAt3 rests. The flexible nonwoven layer Nts thus serves as a support;

- the third CAt3 layer;

- a flexible nonwoven layer Nts.

The filter medium MF1 is described in detail below with reference to FIGS. 7 to 9.

In a nonlimiting example, FIG. 9 illustrates the layers C of the nonlimiting example of FIG. 3g.

As illustrated in FIGS. 7 and 8, the filter medium MF1 has a width La and a length Lg.

As illustrated in FIG. 7, according to a nonlimiting embodiment, the filtering medium MF1 comprises pleating of all of the layers C.

The layers C thus comprise a plurality of folds P1 (in English “pleat”) as illustrated in FIG. 7 and in FIG. 9 which is a sectional view of a zoom of a part of the layers of FIG. 7 Pl folds increase the filtration surface.

Note that the folds Pl have a height h1. In a nonlimiting example, the height h1 is equal to 30mm.

In a nonlimiting embodiment, the filtering medium MF1 comprises return folds Plr as illustrated in FIG. 7 and in FIG. 9. These return folds Plr have a height h2 less than the height h1 of the folds Pl.

In a nonlimiting embodiment, the height h2 is equal to 2/3 of the height h1.

In a nonlimiting embodiment, a return ply Plr is produced every 10 plies PL A return ply Plr is a visual aid for an operator so that the latter can know where to cut the pleated filter medium MF1 to give the final length Lg to the air filter 1 which will be produced from the filter medium MF1.

Thus, a filter medium MF1 has two return plies Plr as illustrated in FIG. 7.

The folds PI and Plr are made in a vertical direction relative to the plane of the filter media MF with a fold oriented in one direction or the other. PI folds are made so that a fold oriented in one direction is adjacent to a fold oriented in the opposite direction. The filter medium MF1 thus comprises a set of layers C folded with alternating folds oriented vertically in one direction and then in the other direction. We obtain an accordion effect.

It will be noted that in another nonlimiting embodiment, the filtering medium MF1 has no folds. It is flat.

As illustrated in FIG. 8, according to a nonlimiting embodiment, the air filter 1 comprises at least one framing strip Bd which makes it possible to frame the filtering medium MF1.

Said at least one framing strip Bd makes it possible to give the final dimensions to the air filter 1. It is greater than the length Lg and the width La of the filtering medium MF1.

Said at least one framing strip Bd makes it possible to frame the plurality of layers C which are folded and form the folds PL

In a nonlimiting embodiment, a framing strip Bd is made of polypropylene such as felt or foam, but also of polyethylene such as foam.

In a nonlimiting embodiment, the air filter 1 comprises two framing strips Bd. In the nonlimiting example illustrated in FIG. 8, two framing strips Bd are glued respectively on two opposite edges of the filter medium MF1 .

In another nonlimiting example not illustrated, four framing strips Bd are respectively glued to the four edges of the filter medium MF1.

It will be noted that the framing strips Bd can be connected to each other, in particular when the four edges of the filtering medium MF1 are framed.

The filter medium MF1 thus framed results in the air filter 1 as illustrated in FIG. 8 of length L1 and width L2 defined by the width La of the filter medium MF1.

o Two MFI, MF filter media?

According to a second nonlimiting embodiment, the air filter 1 comprises two filter media MF1, MF2 as illustrated in FIGS. 5a to 5c.

Each filter medium MF1, MF2 comprises at least one layer of adsorbent material A.

Thus, the air filter 1 comprises, as illustrated in FIGS. 5a and 5b:

- a first filter medium MF1 comprising said layer CA1 of the adsorbent material A;

a second filter medium MF2 comprising said at least one layer CAt2 treated with the adsorbent material A.

In a nonlimiting embodiment, at least one filtering medium MF1, MF2 comprises a rigid nonwoven layer Ntr. The rigid nonwoven layer Ntr makes it possible to stiffen the filtering medium MF1, MF2 to which it belongs.

The rigid nonwoven layer Ntr can also serve as a support for a layer of the adsorbent material A (in the case where it is not in the form of fabric).

So :

- The first filter medium MF1 further comprises a rigid nonwoven layer Ntr; and or

- The second filter medium MF2 also comprises a rigid nonwoven layer Ntr.

In the nonlimiting example of FIG. 5a or 5b, the second filter medium MF2 comprises only a single layer CAt2 treated and each filter medium MF1, MF2 comprises a rigid nonwoven layer Ntr.

In the nonlimiting example of FIG. 5c, the second filter medium MF2 comprises two treated layers CAt2 and CAt3, and each filter medium MF1, MF2 comprises a rigid nonwoven layer Ntr.

In a nonlimiting embodiment, at least one filtering medium MF1, MF2 comprises a flexible nonwoven layer Nts. The flexible nonwoven layer Nts makes it possible to filter the dust and to maintain in place the adsorbent material A on its support layer Ntr.

So :

- The first filter medium MF1 further comprises a flexible nonwoven layer Nts; and or

- The second filter medium MF2 further comprises a flexible nonwoven layer Nts.

In a nonlimiting embodiment (not illustrated), at least one layer CA1, CAt2, CAt3 of the adsorbent material A is in the form of fabric. In this case, there is no associated flexible nonwoven layer Nts which serves as a support as described above.

It will be noted that one or more layers CA1, CAt2, CAt3 of the adsorbent material A may be in the form of fabric.

When all the layers of adsorbent material A are in the form of fabric, it is possible to have no rigid nonwoven layer Ntr in the first filtering medium MF1 and / or the second filtering medium MF2 if the layers of each filtering medium are sufficient rigid by themselves. This can in particular be the case when there are two or more layers of adsorbent material A in the form of fabric as seen above.

In a nonlimiting embodiment, a nonwoven layer Nt serves as a support for a layer CA1, CAt2, CAt3 of adsorbent material A which is not in the form of fabric.

Thus, in a nonlimiting embodiment,

- Said layer CA1 of the adsorbent material A is in the form of fabric or said first filtering medium MF1 further comprises a nonwoven layer Nt which serves as a support for said layer CA1 of the adsorbent material A; and or

- Said layer CAt2 of the adsorbent material A is in the form of fabric or said second filtering medium MF2 further comprises a nonwoven layer Nt which serves as support for said layer CAt2 of adsorbent material A treated; and or

- in the case where there is a Cat3 layer, said layer CAt3 of the treated adsorbent material A is in the form of fabric or said second filtering medium MF2 further comprises a nonwoven layer Nt which serves as a support for said layer CAt3 of adsorbent material A treated.

In a first nonlimiting embodiment, the two filter media MF1, MF2 are separated by a space as illustrated in FIGS. 5a or 5c. In a first nonlimiting embodiment, the two filter media MF1, MF2 are contiguous as illustrated in FIG. 5b. This reduces the height of the air filter 1 and thus has a more compact air filter if necessary.

O Trojs .filtrating media MF1., MF2 _A .MF3

According to a third nonlimiting embodiment, the air filter 1 comprises at least three filter media MF1, MF2, MF3.

As illustrated in the nonlimiting example of FIGS. 6a and 6b, the air filter 1 comprises three filter media MF1, MF2, MF3.

Each filter medium MF1, MF2, MF3 comprises at least one layer of adsorbent material A.

Thus, the air filter 1 comprises as illustrated in FIGS. 6a and 6b:

- a first filter medium MF1 comprising said first layer CA1 of the adsorbent material A;

a second filter medium MF2 comprising said second layer CAt2 treated with the adsorbent material A so as to filter at least one gas

G1 selectively;

a third filter medium MF3 comprising said third layer CAt3 treated with the adsorbent material A so as to filter at least one gas G2 selectively.

In a nonlimiting embodiment illustrated in FIGS. 6a and 6b, at least one filtering medium MF1, MF2, MFR3 comprises a rigid nonwoven layer Ntr. The rigid nonwoven layer Ntr makes it possible to stiffen the filtering medium MF1, MF2, MF3 to which it belongs.

The rigid nonwoven layer Ntr can also serve as a support for a layer of the adsorbent material A (in the case where it is not in the form of fabric).

So :

- The first filter medium MF1 further comprises a rigid nonwoven layer Ntr; and or

- The second filter medium MF2 further comprises a rigid nonwoven layer Ntr; and or

- The third filter medium MF3 further comprises a rigid nonwoven layer Ntr.

In the nonlimiting example of FIGS. 6a and 6b, each filtering medium MF1, MF2, MF3 comprises a rigid nonwoven layer Ntr.

In a nonlimiting embodiment illustrated in FIG. 6b, at least one layer CA1, CAt2, CAt3 of the adsorbent material A is in the form of fabric. In this case, there is no associated flexible nonwoven layer Nts which serves as a support as described above.

It will be noted that one or more layers CA1, CAt2, CAt3 of the adsorbent material A may be in the form of fabric.

When all of the layers of adsorbent material A are in the form of fabric, it is possible to have no rigid nonwoven layer Ntr in the first filter medium MF1 and / or the second filter medium MF2 and / or the third filter medium MF3 if the layers of each filter media are fairly rigid by themselves. This may in particular be the case when there are two or more layers of adsorbent material A in the form of fabric in a filtering medium.

In a nonlimiting embodiment illustrated in FIG. 6a, a rigid nonwoven layer Ntr serves as a support for a layer CA1, CAt2, CAt3 of adsorbent material A which is not in the form of fabric. Furthermore, a flexible nonwoven layer Nts serves to maintain the adsorbent material A on its support layer Nt.

Thus, in a nonlimiting embodiment,

- Said first layer CA1 of the adsorbent material A is in the form of fabric or said first filtering medium MF1 further comprises a nonwoven layer Nt which serves as a support for said first layer CA1 of the adsorbent material A;

- Said second layer CAt2 of the adsorbent material A treated is in the form of fabric or said second filtering medium MF2 further comprises a nonwoven layer Nt which serves as a support for said second layer CAt2 of the adsorbent material A treated.

- Said third layer CAt3 of the treated adsorbent material A is in the form of fabric or said third filtering medium MF3 further comprises a nonwoven layer Nt which serves as a support for said third layer CAt3 of the treated adsorbent material A.

In a first nonlimiting embodiment as illustrated in FIGS. 6a and 6b, two adjacent filter media are separated by a space. One can have all adjacent filter media spaced between them. Thus, as illustrated in the nonlimiting example of the three filter media MF1, MF2, MF3 of FIGS. 6a and 6b, there are two spaces, a space between the filter media MF1, MF2 and a space between the filter media MF2 and MF3.

In a second nonlimiting embodiment (not illustrated), two filter media are contiguous. This reduces the height of the air filter 1 and thus has a more compact air filter if necessary.

You can have all adjacent filter media adjacent to each other.

Note that one can have a combination of these two embodiments.

It will be noted that of course the air filter 1 may comprise more than a third layer treated CAt3. In this case the additional treated layers CAt3 are suitable for filtering other gases G2 for example.

Thus, in nonlimiting embodiments, the air filter 1 comprises:

- As illustrated in FIG. 10, a single filter medium MF1 with two framing strips Bd, said filter medium comprising all of the layers C of the air filter 1; or

- As illustrated in FIG. 11, two filter media MF1, MF2 superimposed one on the other with two framing strips Bd framing the two filter media MF1, MF2, each filter media MF1, MF2 respectively comprising a part C1, C2 of the layers C of the air filter 1, said parts of layers C1, C2 being superimposed between them; or

- as illustrated in FIG. 13, three filter media MF1, MF2, MF3 superimposed one on the other with two framing strips Bd framing the three filter media MF1, MF2, MF3 each filter media MF1, MF2, MF3 respectively comprising a part 01, C2, C3 of the layers C of the air filter 1, said parts of layers C1, C2, C3 being superimposed between them.

Note that having a plurality of filter media MF1, MF2, MF3 etc. superimposed makes it easier to fold the layers C of each filter medium MF1, MF2, MF3 than if they were all contained in a single filter medium MF1. However, the total height of the air filter 1 is in this case greater than that of the air filter 1 comprising a single filter medium MF1. Consequently, according to the customer's request and according to the space provided for the air filter 1 in the motor vehicle V, the air filter 1 will be designed with a single or several filter media.

Of course, the description of the invention is not limited to the embodiments described above.

Thus, in a nonlimiting embodiment, the air filter 1 comprises more than two treated layers.

Thus, in a nonlimiting embodiment, in addition to the layer CA1, the air filter 1 can comprise three treated layers adapted to selectively filter respectively three different gases, for example SO2, NOX, and NH3.

Thus, in a nonlimiting embodiment, the air filter 1 comprises more than three filter media.

Thus, in a nonlimiting embodiment, the air filter 1 can comprise a treated layer adapted to selectively filter respectively a gas which is a volatile organic compound VOC.

Thus, in the field of motor vehicles, in non-limiting embodiments, the air filter 1 can be an air filter for:

- engine;

- For a passenger compartment H of a motor vehicle V, said air filter F being arranged in a heating and / or air conditioning device of said motor vehicle V.

Thus, the air filter described can be used in fields other than that of motor vehicles, such as in nonlimiting examples, the fields:

- of the building. In this case, in a nonlimiting example, the air filter 1 is an air conditioning air filter for buildings or an air filter dedicated to people within the framework of the building;

- IT protection. In this case, in a nonlimiting example, the air filter 1 is an air filter for a computer;

- hygiene and health. In this case, in a nonlimiting example, the air filter 1 is dedicated to people for filtering dust;

- household appliances. In this case, in a nonlimiting example, the air filter 1 is an air filter for a vacuum cleaner.

Thus, the invention described has the following advantages in particular:

a very significant reduction (in a nonlimiting example 80%) of SO2 and / or NOX and / or NH3 which arrives in the fuel cell over the entire duration of the air filter 1 and this for a long period, in a non-limiting example six months;

- the fact of arranging the air filter 1 relative to the air inlet of the fuel cell so that the largest particles of gas are filtered first and the smallest particles of gas are filtered last obtain an efficient air filter 1.

Claims (8)

1. Air filter (1) for a motor vehicle (V), according to which said air filter (1) comprises a plurality of layers (C) comprising at least two layers (CA1, CAt2) of an adsorbent material (A) , at least one layer (CAt2) of the adsorbent material (A) of which is treated so as to selectively filter a gas (G), according to which said air filter (1) comprises at least one filtering medium (MF1, MF2, MF3) comprising at least one of said layer (CA1, CAt2) of adsorbent material (A), said air filter (1) comprising at least one framing strip (Bd) which makes it possible to frame the filtering medium (MF1, MF2 , MF3). 2. Air filter (1) according to claim 1, according to which said at least one layer of the treated adsorbent material (CAt2) has undergone a physico-chemical treatment. 3. Air filter (1) according to any one of the preceding claims, according to which the adsorbent material (A) is activated carbon or a zeolite. 4. Air filter (1) according to any one of the preceding claims, according to which said air filter (1) comprises at least three layers (CA1, CAt2, CAt3) of an adsorbent material (A) of which: - a first layer (CA1) of the adsorbent material (A); - a second layer (CAt2) of the adsorbent material (A) treated so as to selectively filter a gas (G1); - at least a third layer (CAt3) of the adsorbent material treated so as to selectively filter a gas (G2). 5. Air filter (1) according to any one of the preceding claims, wherein said air filter (1) further comprises at least one nonwoven layer (Nt). 6. Air filter (1) according to any one of the preceding claims, according to which at least one layer of the adsorbent material (CA1, CAt2, CAt3) is in the form of fabric. 7. Air filter (1) according to any one of the preceding claims, according to which the filtering medium (MF1, MF2, MF3) comprises a nonwoven layer (Nt) which serves as a support for said at least one layer (CA1, CAt2, CAt3) of the adsorbent material (A). 8. Fuel cell comprising an air filter (1) according to any one of the preceding claims 1 to 7.