FR3117878A1 - Cartridge housing a filter pad encapsulated in a sealing ring, intended to be removably attached to a respiratory protection mask. - Google Patents

Abstract

Cartridge housing a filter pad encapsulated in a sealing ring, intended to be removably attached to a respiratory protection mask. The invention relates to a filtration cartridge (5, 5', 5''), intended to be removably attached to a health protection mask (1), comprising: - a body extending along a longitudinal axis (X ), the body being in two parts (51, 52) assembled together to define a housing, each of the two parts being pierced with at least one through hole opening into the housing; - at least one piece in the form of a pellet (6) having a total porosity greater than 40%; - a sealing ring (53) made of elastomer of substantially U-shaped cross-section inside which the pellet is held, the ring being housed in the housing of the body while being held with adjustment against an interior portion of the one and/or the other part of the body. Figure 9A

Description

Cartridge housing a filter pad encapsulated in a sealing ring, intended to be removably attached to a respiratory protection mask.

The present invention relates to a cartridge housing a filtering pellet, preferably ceramic, encapsulated in a sealing ring, intended to be removably attached to a respiratory protection mask.

The applications of the invention are numerous, including the medical and paramedical sector, health security services (ambulance, firefighters, civil security, etc.), the general public, in particular the elderly, businesses, deaf people or hard of hearing.

The technological development of the ^20th century was accompanied by the introduction of a range of respiratory protection masks adapted to risk environments.

Thus, in a hospital environment, surgical protective masks are used. Such a mask consists of one or more layers of textile or paper held on the face of the wearer by elastic bands or straps. Typically, a surgical mask comprises a stack consisting of a non-woven polypropylene (PP) outer layer / a PP microfiber filter layer / an acrylic backing / a non-woven PP inner layer. Fine particles suspended in an aerosol that can be filtered by surgical masks can be of the order of 3µm ± 0.3 µm (D50 by volume), with an efficiency of up to 98%

A major drawback of these masks is that they are dedicated to single use, and thus generate a significant amount of waste because they cannot be recycled.

In addition, these masks are designed to filter only bacteria and viruses. Even if they de facto filter certain pollutants and/or certain particles of matter, they are not designed for this.

Also, the intrinsic quality of protection of these masks is relatively low, because they are mainly intended to avoid the projections of the wearers on the close environment and not the reverse.

In addition, in use, the nursing staff who wear such masks cannot really communicate with the patients, because the textile layer(s) on the one hand, form a sound barrier and on the other hand, are opaque, which prohibits lip reading by patients.

In the context of the coronavirus epidemic, designated COVID-19, washable textile masks have been produced. These washable masks have the same inherent limitations as surgical masks. Effective cleaning requires compliance with specific conditions, in particular drying at high temperature and/or ironing. In addition, they are often thick and therefore relatively heavy and uncomfortable for some users, with in particular the frequent risk of the glasses fogging up. The manufacture of such textile masks is also difficult to automate, since it requires sewing operations.

Finally, as with surgical masks, the seal between a mask and its wearer is non-existent, which is harmful in environments where aerosols circulate which may be contaminated, for example with viruses of the COVID-19 type.

In dusty environments, such as construction sites, or those with the additional presence of harmful gases, different technologies for the realization of respiratory protection masks can be implemented.

Thus, there are masks with a preformed shell with one or more housings in which filtering materials are housed. These masks in principle have an improved filtering power, for example FFP2 or FFP3 according to the NF EN 149 and NF EN 13724-7 standards.

In particular, FPP3 type shell masks are known designed to filter fine and very fine particles, and up to 99% of fine particles of the order of 0.06 to 0.1 μm (D50 by volume).

Shell military masks are intended exclusively to filter gaseous pollutants, such as CO ₂ or nitrogen oxide.

These shell masks are for the most part quite heavy, to the point that wearing them for a long time cannot reasonably be considered.

In addition, their relative rigidity means that the interface with the skin is often imperfect, especially for certain face morphologies, with here again the frequent risk of fogging of wearers' glasses.

To improve the interface with the skin, it is common to add a metal insert to conform to the shape of the nose or a foam seal. However, these elements complicate the manufacture of masks and their recycling.

In the emergency of the COVID-19 epidemic, some plastic masks were made by additive manufacturing. These masks comprise a flexible part forming a skirt connected to a central rigid part in the form of a shell which houses one or more layers of filtering material between two grids including a cap which can be removed to allow replacement of the layers of filter material. The masks offered are also relatively heavy and uncomfortable to wear over a long period. In addition, the proposed additive manufacturing is incompatible with mass production likely to meet strong demand in times of health crisis.

Also, when a user is wearing a goggle, they are usually inaudible.

In addition to all the aforementioned drawbacks, most of the existing respiratory protection masks are designed for a type of species to be filtered which is fixed (fine particles or gaseous pollutants or viruses and bacteria) and/or for a given level of efficiency. (FFP1 or FFP2 or FFP3).

Above all, none of the existing masks are imperishable.

Finally, none of them really benefited from an aesthetic design.

The applicants proposed in patent application FR2006308 filed in France on June 17, 2020 a respiratory protection mask, with a removable filtration cartridge housing a ceramic pellet as filter material.

The applicants have sought to further improve the production of these removable cartridges so that their manufacture is compatible with mass production, in particular if it must be done in a short time and that they guarantee perfect sealing and durability of the pellets, in particular ceramic.

To do this, the invention firstly relates to a filtration cartridge, intended to be removably attached to a health protection mask, comprising:

- a body extending along a longitudinal axis (X), the body being in two parts assembled together to define a housing, each of the two parts being pierced with at least one through hole opening into the housing ;

- at least one part in the form of a pellet having a total porosity greater than 40%;

- an elastomer sealing ring of substantially U-shaped cross-section inside which the pellet is held, the ring being housed in the housing of the body while being held with adjustment against an inner portion of one and/or or other part of the body.

Advantageously, the pellet is made of sintered ceramic.

The invention essentially consists of a ring, the shape of which fits perfectly by encapsulating it with a pellet, in particular of ceramic, which can be intrinsically fragile, which thus makes it possible to guarantee both perfect sealing and shock absorption and par- there to avoid the risk of breakage of the pellet.

Preferably, the two parts of the body are press-fitted into each other.

According to an advantageous embodiment, the inner portion comprises at least one annular shoulder against which the sealing ring abuts directly or indirectly via a spacer.

According to an advantageous variant embodiment, the sealing ring comprises at least one peripheral sealing lip in direct contact with the inner portion.

According to another advantageous variant embodiment, the sealing ring comprises, at the bottom of the U, at least one release groove adapted to create an empty space between the ring and the corners of the pellet.

Advantageously, the elastomer of the ring is a silicone.

According to an advantageous embodiment, the cartridge comprises at least one mechanical protection grid for the pellet, the grid being axially supported against an axial face of the sealing ring and held inside in the housing of the body. Thanks to this grid, the risk of intrusion of any object into the ceramic pellet is eliminated. Preferably, the cartridge comprises two protective grids each arranged on either side of the ring against one of its axial faces.

According to an advantageous variant embodiment, one and/or the other of the parts of the body is colored with a color defined according to a code according to the level of filtration of the tablet, for example of the FMP1, FMP2 or even FMP3 type. Thus, one can immediately visually identify the level of filtration of a cartridge outside the mask or in a configuration fixed in a health protection mask.

For the purposes of integration and/or complementary design with that of a curved sanitary protection mask, one and/or the other of the parts of the body forms a cage of curved shape towards the outside.

For aesthetic purposes and/or to optimize the circulation of the air flows, provision may be made for at least one of the two parts to be pierced with a plurality of through holes of different diameters, preferably distributed in concentric circles.

The invention also relates to a method for producing a filtration cartridge as described above, comprising the following steps:

- Realization by stamping of each of the two parts of the body;

- installation with maintenance by adjustment of the sealing ring around a pad, preferably in sintered ceramic;

- housing with abutment of the sealing ring sub-assembly around the pad in an annular portion of the two parts of the body, if necessary with the interposition of a spacer;

- force fitting of one of the two parts into the other of the two parts of the body.

The invention also relates to a sintered ceramic part in the form of a pellet, intended to be implanted in a cartridge as described above, the ceramic part having a total porosity greater than 40%, preferably greater than 50%, preferably greater than 55%, or even greater than 60%, or even greater than 70% and preferably less than 90%, or even less than 85%, or even less than 80%, preferably between 55 and 85%.

Such total porosity offers a microstructure perfectly suited to the treatment of pathogens.

A ceramic pellet also has the advantage of being able to be cleaned and/or purified to be reused. It therefore generates little waste.

By “ceramic” is meant in the context of the invention, any non-metallic and non-organic material.

The term "sintering" means the consolidation by heat treatment at over 1100°C of a preform, possibly with partial or total melting of some of its constituents (but not all of its constituents, so that the preform is not transformed into a liquid mass).

By "recrystallized silicon carbide" is meant silicon carbide recrystallized by high temperature treatment of the ceramic part, and in particular of the ceramic foam. Recrystallization is a well-known phenomenon corresponding to consolidation by sublimation of the smallest grains of silicon carbide then condensation to form the bond with the largest grains.

The total porosity, in percentage, is typically equal to 100 x (1 - the ratio of the geometric density divided by the absolute density).

Geometric density is measured according to ISO 5016:1997 or EN 1094-4 and expressed in g/cm3. It is conventionally equal to the ratio of the mass of the sample divided by its apparent volume.

The absolute density value, expressed in g/cm ³ , is conventionally measured by dividing the mass of a sample by the volume of this ground sample so as to substantially eliminate the porosity.

The ceramic part is made of silicon carbide or cordierite or aluminum titanate or zirconia or alumina or mullite or silica or their mixtures. According to a variant, the ceramic part comprises more than 80% by mass of silicon carbide (SiC), or even more than 90% of silicon carbide, or even more than 95% of silicon carbide, or even consists essentially of silicon carbide . According to a variant, the silicon carbide is recrystallized silicon carbide, in particular in the alpha form. Recrystallized silicon carbide is particularly interesting, because it makes it possible to obtain parts with a microstructure whose pores are almost exclusively open and highly interconnected.

According to another variant, the ceramic part consists, in mass percentage on the basis of the crystallized phases, of 25 to 55% mullite (3Al ₂ O ₃ -2SiO ₂ ), 20 to 65% corundum (Al ₂ O ₃ under alpha crystalline form), 10 to 40% zirconia (ZrO ₂ ), mullite, corundum and zirconia together representing more than 80%, preferably more than 90%, preferably more than 95%, preferably more than 98 % of the mass of the crystallized phases.

Forming processes by foaming and tape casting are particularly suitable for the production of parts with complex shapes, in particular pellets, before firing to avoid/limit machining steps.

Advantageously, a ceramic part according to the invention has a thickness of between 1 and 20 mm, preferably greater than 2 mm, or even greater than 3 mm and/or less than 15 mm, or even less than 10 mm.

Preferably, the ceramic part also has one or more of the following characteristics:

- the median pore size (D50 by volume, measured by mercury porosity) is greater than 1 µm, or even greater than 5 µm, or greater than 10 µm, or greater than 20 µm, or greater than 30 µm, or greater than 40 µm and less than 400 μm, or even less than 300 μm, or even less than 200 μm, or even less than 160 μm, or even less than 150 μm;

- pores larger than 300 μm represent less than 10% by volume, or even less than 5% by volume;

- tortuosity is greater than 1, or even greater than 1.1, or greater than 1.2, or greater than 1.3, or greater than 1.4 and less than 2, or greater than 1.9, or greater than 1.8, or even less than 1.7. The tortuosity is measured by nanotomography. The images have a resolution suitable for binarization. The use of software such as iMorph© makes it possible to obtain a geometric characterization in three dimensions and to calculate the tortuosity. The tortuosity is defined as the ratio between the shortest route allowing the sample to cross in the direction of its thickness, within its porosity, and the distance or the line segment joining the starting point and the starting point. arrival corresponding to this route.

According to a first advantageous embodiment, the ceramic part is a ceramic foam having a plurality of cells, the majority of these cells being connected to other adjacent cells by cellular windows or pores. A cell on the surface of the ceramic foam also generally has one or more openings to the outside. The walls delimiting the cells have a so-called “intergranular” porosity. They are in fact formed by agglomeration of particles, this agglomeration leaving interstices or “intergranular pores” between the particles. An example of ceramic foam according to this embodiment is described in EP1778601.

According to this first mode, the ceramic foam advantageously has one or more of the following characteristics:

• the intergranular porosity is at least 5%, preferably at least 8%, more preferably at least 10% and/or less than 25%, or even less than 20%;
• the median size of the intergranular pores is less than 25 μm, or even less than 20 μm and greater than 4 μm, or even greater than 7 μm;
• the median size of the cellular pores is less than 400 μm, even less than 300 μm, even less than 200 μm, even less than 180 μm, even less than 160 μm and greater than 40 μm, even greater than 50 μm, even greater than 80μm;
• the pore size distribution is bimodal;
• the total porosity is greater than 55%, or even greater than 60%, or even greater than 70%.

An analysis using a mercury porosimeter makes it possible to highlight several porosity characteristics: a distribution of the size of the pores presenting two distinct peaks and representative of the two families of pores, the median size of the pores of each of the families being given by the position of the apex of each peak.

A ceramic foam advantageously has an essentially open porosity, which makes it accessible and allows a high filtration capacity.

A ceramic foam advantageously makes it possible to filter particles whose size is up to 30 times smaller than the median pore size, which makes it possible to limit the pressure drop.

A ceramic foam advantageously presents an excellent compromise between the pressure drop and the filtration capacity, which makes it possible to form a mask having both good breathability and effective filtration.

According to a second advantageous embodiment, the ceramic part consists of several superposed ceramic layers having different respective total porosities. Preferably, the total porosity and the median pore size of the layer constituting the air inlet face to be filtered are lower than those of the other layer(s). The different layers can result from the impregnation of part of the ceramic piece.

In particular when the ceramic part is a ceramic foam of recrystallized silicon carbide, a layer can be obtained by impregnating part of the thickness of the part with a slip based on silicon carbide and optionally comprising pore-forming agents; the slip then fills both the cellular pores and the intergranular porosity constituting a differentiated layer in the ceramic piece. Preferably, the impregnated part is the air inlet face to be filtered.

Preferably, this impregnated part has:

• a total porosity less than the total porosity of the non-impregnated part. Preferably the total porosity of the impregnated part is greater than 30%, or even greater than 35% and preferably less than 85%, or even less than 80%, or even less than 70%, or even less than 60%, or even less than 50 %; and or
• pores whose median size is greater than 1 μm, or even greater than 2 μm, or even greater than 3 μm and less than 20 μm, or even less than 10 μm, or even less than 5 μm; and or
• a thickness of between 5 and 500 μm, preferably greater than 10 μm and/or less than 400 μm, or even less than 200 μm, or even less than 100 μm.

According to an advantageous variant, whatever the type of ceramic part, the ceramic part is provided with a coating for inactivating one or more pathogens.

The inactivation coating is tailored to the pathogens to be inactivated.

In particular, the inactivation coating can be a coating eliminating one or more pathogenic agents, for example bactericidal and/or virucidal. The inactivation coating may in particular consist of nanoparticles, in particular based on silver and/or copper.

The coating can be deposited by impregnation directly in the porous structure, in particular when it is a ceramic foam, directly on the walls of the foam,

The coating can be deposited on one of the outer faces of the ceramic part, preferably the air inlet face to be filtered.

The very porous microstructure, and in particular the microstructure of a ceramic foam, advantageously offers a very large exchange surface with the inactivation coating.

The advantages of a mask with at least one filtration cartridge according to the invention are numerous, among which we can mention:

• very effective respiratory protection, the flow of air inspired and exhaled by a wearer of the mask being guided to cross only the filter material cartridge(s) because the lip envelope ensures perfect sealing of the internal volume of the mask surrounding the mouth and the nose and the sealing ring ensure a perfect seal within a cartridge;
• guaranteed mechanical protection of the ceramic pellets;
• the possibility of making the mask very easily and quickly upgradeable, by carrying out a removable assembly/disassembly of cartridges configured according to the desired level of filtration FMP1, FMP2, FMP3 relates to the masks and, where appropriate, virucidal and/or bactericidal properties;
• comfort for the wearer due to the lightness of the possible materials for the various components of the mask and the flow of air to be inhaled, which can be well calibrated;
• a very long lifespan or even imperishability through the use of resistant and stable materials over time, in particular for ceramics which can be used to guarantee effective filtration;
• the possibility of recycling all the components of the mask;
• a very aesthetic appearance by the implementation of a transparent wall preferably curved to match the shape of a face, which also allows lip reading;
• the absence of fogging on a wearer's glasses because the sealing lip guarantees that no air exhaled by the wearer can come in the direction of the eyes;
• the implementation of a sound amplification function by a suitable configuration of the air exhaust valve;
• effective eye protection with a visor that can be quickly and easily integrated into the mask;
• a manufacturing process compatible with mass production in a short time, all the components being able to be produced by perfectly mastered processes, such as injection molding or thermoforming of plastic or elastomer material, for the rigid frame, the casing, exhaust valve, visor, attachment straps, or stamping or cutting for parts of cartridge bodies, foaming or sintering of ceramic pellets as filter materials;
• easy cleaning of all components, in particular by going through the dishwasher, or even sterilization in an autoclave. Ceramic pellets, particularly in recrystallized silicon carbide, are perfectly suited to being washed and reintegrated into the mask multiple times. The chemical and temperature resistance of recrystallized silicon carbide makes it very well suited and resistant to multiple washing agents, even when hot;
• traceability of the mask wearer, particularly useful in very restrictive environments, such as hospital environments, dusty environments, with harmful gas atmospheres, etc.

Other advantages and characteristics of the invention will emerge better on reading the detailed description of examples of implementation of the invention given by way of illustration and not limitation with reference to the following figures.

there is a perspective view from the front of an example of a respiratory protection mask with removable filter cartridges according to the invention.

there is a perspective view from the back of the mask example according to the .

there is a partially exploded view of a mask according to Figures 1 and 2.

there shows a front view of another example of respiratory protection with removable filter cartridges according to the invention as it is in the configuration worn by a user.

there is a profile view of the .

there is a front view of the example of Figures 4 and 5, the removable visor having been removed.

there is a rear perspective view of a first example of a filtration cartridge with filtering material according to the invention to be removably attached to a respiratory protection mask.

there is a front perspective view of a removable filter cartridge according to .

there is a front view of the filter cartridge according to Figures 7 and 8.

there is a cross-sectional view along AA of the .

there is a detail view of the .

there is a perspective view of a sub-assembly consisting of a ceramic pellet as filter material and a sealing ring, the sub-assembly being housed in a filter cartridge according to the invention.

there is a front view of a subset of the .

there is a cross-sectional view along AA of the sealing ring according to .

there is a detail view of the .

there is a front view of a sub-assembly according to an alternative embodiment of the sealing ring

there is a cross-sectional view along AA of the sealing ring according to .

there is a detail view of the .

there is a rear perspective view of a second example of a filtration cartridge with filtering material according to the invention to be removably attached to a respiratory protection mask.

there is a front perspective view of a removable filter cartridge according to .

there is a front view of the filter cartridge according to Figures 13 and 14.

there is a cross-sectional view along AA of the .

there is a detail view of the .

there is a rear perspective view of a third example of a filtration cartridge with filtering material according to the invention to be removably attached to a respiratory protection mask.

there is a front perspective view of a removable filter cartridge according to .

there is a front view of the filter cartridge according to Figures 15 and 16.

there is a cross-sectional view along AA of the .

there is a detail view of the .

there is a schematic view of the filtration principle of a mask with filtration cartridges according to the invention, both on inspiration and on expiration of the user.

there is a detailed sectional view of a mask produced at the level of a removable filtration cartridge according to the invention arranged on one of the side edges.

there is a detail sectional view of a mask produced at the level of a removable cartridge arranged at the level of the plane of symmetry of the mask.

there is a perspective view of an example of an escape valve mounted in a mask.

there is a perspective view from the front of another example of a respiratory protection mask with cartridge according to the invention.

there is a perspective view from the rear of the other mask example according to .

detailed description

Throughout the application, the terms "top", "bottom", "above", "below", "upper" and "lower" are to be understood by reference in the configuration worn by a user in a standing position. with the head vertical.

Likewise, the terms “front” and “rear” are to be understood by reference to this configuration.

An example of mask 1 with removable filtration cartridges according to the invention is shown in Figures 1 to 3.

In this illustrated example, the mask 1 is symmetrical with respect to a longitudinal median plane.

The mask 1 firstly comprises a rigid frame 2 to be placed on the face of a user. This rigid reinforcement 2 is for example made of polycarbonate (PC) by injection molding.

A sealing envelope 3 is fixed by snap-fastening with at least the rear of the frame 2. As can be seen in FIGS. 4 to 6, this sealing envelope 3 is shaped to match the shape of the face by surrounding an area comprising nose and mouth. More specifically, the sealing envelope 3 comprising, in its rear part 30, a flexible sealing lip 31 shaped to be in contact with the face by delimiting the zone. The rear part 30 notably comprises a narrower projecting zone, intended to match the shape of the bridge of the nose. The sealing envelope 3 is for example made of silicone, a flexible material which allows a perfect seal in contact with the skin but also brings lightness to the mask and wearing comfort for the user.

A transparent interface wall 4 is glued to the front of the frame, so as to make the mouth visible, as can be seen in FIGS. 4 to 6. This transparent interface wall 4 is for example made of polycarbonate ( PC) or poly(methyl methacrylate) (PMMA). As illustrated in Figures 4 to 6, this wall 4, like the rigid frame 2, is curved in the form of a spherical portion for the aesthetics of the mask and to best match the contour of the wearer's face.

The mask 1 further comprises two identical filtration cartridges 5 fixed symmetrically on either side of the median plane of the mask. Each of these two cartridges 5 is removably attached to the casing 3, through one of the side edges of the casing. More precisely, each of the cartridges 5 is snapped onto the sealing casing 3 by passing through through openings 40, 20, 32 aligned, made respectively in the transparent wall 4, in the rigid reinforcement 2 and in the casing of sealing 3.

Each of the two removable side cartridges 5 houses at least one filter material 6 in the form of a sintered ceramic pellet.

A first example of removable cartridge 5 is shown in Figures 7 to 9B.

This cartridge 5 comprises a body 50 in two parts 51, 52 made assembled to each other defining a housing. The parts 51, 52, of the body are metallic and for example produced by stamping an aluminum sheet, a light material which is easy to machine.

One of the parts 51 forms a strapping/closing element of the body. This element 51 is provided with a peripheral groove 510 which allows fixing by direct snap-fastening with a continuous bead made on an opening periphery of the envelope 3 of the mask as explained below.

One of the parts 52 forms a cage that is preferably outwardly domed in order to best match the shape of the reinforcement 2, of the casing 3 and of the transparent interface wall 4. This cage 52 is pierced a plurality of through holes 520 of different diameter, preferably distributed in concentric circles.

As clearly visible in , the two parts 51, 52 of the body are advantageously assembled to each other by press fitting along an annular zone 511.

The cage 52 and/or the closing element of the body are colored with a color defined according to a code according to the level of filtration of the tablet, for example of the FMP1, FMP2 or even FMP3 type.

The ceramic disc 6 is held in the bottom 530 of an elastomer sealing ring 53 of substantially U-shaped cross-section. This ring 53 serves both as a sealing element over the entire circumference of the disc 6 and to protect it mechanically against shocks. The elastomer of ring 53 is made of flexible material(s) and has a shock-absorbing function. Preferably, the ring 53 is made of silicone, rubber, etc.

As illustrated in , the ring 53 is housed in the body 50 abutting against an annular shoulder via a spacer 55. The ring 53 is held axially with adjustment between this spacer 55 and a mechanical protection grid 54 at plurality of through holes 540.

These holes 540 have a diameter large enough to let the air flow through the ceramic pad 6 and small enough to prevent any intrusion with contact of an object, in particular a point with the ceramic pad 6.

An advantageous example of sealing ring 53 is shown in Figures 10, 11, 11A and 11B.

The ring 53 comprising two peripheral sealing lips 531 in direct contact with the inside of the cage 52.

The sealing ring 53 also includes, at the bottom of the U, two clearance grooves 532 adapted to create an empty space between the ring and the corners of the pad. This empty space thus created makes it possible not to pressurize the corners of the ceramic disc 6 .

The ring 53 finally comprises, on either side of the U, peripheral support lips 533 which extend axially and are intended for one to be in flexible support with the mechanical protection grid 54 and for the other with spacer 55.

An advantageous variant of the sealing ring 53 is shown in Figures 12, 12A and 12B.

The sealing ring 53 here consists of two annular parts 53.1, 53.2 assembled together, preferably by gluing or at their junction 534. One of the parts 53.1 forms a bowl for housing a filter pad 6 and the another 53.2 forms a holding flange.

The housing bowl 53.1 and the retaining flange 53.2 each consist of two concentric rings, respectively 535, 536, and 537 and 538 interconnected by a number of three connecting arms 539 at 120° from each other. This guarantees optimum mechanical retention of the filter pad 6 without inducing substantial pressure drops.

As shown, each of the concentric rings 535, 536, 537, 538 advantageously comprises a peripheral bearing lip 533.

This variant of sealing ring 53 is particularly implemented for filter pads 6 of larger dimensions, the porosity of which is reduced and the filtering surface is increased.

Figures 13 to 15B illustrate another example of a filter cartridge 5' with parts 51, 52 made by stamping. In this example, the holes 520 of the cage 52 are enlarged with, as a corollary, a second mechanical protection grid 54 between the sealing ring 53 and the spacer 55.

Figures 16 to 18B illustrate another example of a 5" filter cartridge with parts 51, 52 made by stamping. In this example, the holes 520 of the cage 52 are widened with another shape.

The mask 1 comprises another cartridge 7 removably attached to a front part 33 of the casing 3, which is arranged so that in the configuration worn by the user, this cartridge 7 is substantially facing the chin. This central cartridge 7 also houses at least one ceramic pellet 6, preferably of the same type as that of the side cartridges 5, the dimensions (shape, thickness) being able to vary.

One or two exhaust valves 8 is (are) fixed in the frame 2 in front of the central cartridge 7.

We will now describe with reference to the , the filtration principle of the mask 1 thanks to the different filtration cartridges 5, 7.

The air, possibly contaminated, inspired by the wearer of the mask 1 passes through the side filtration cartridges 5 while being filtered by their pellets 6 of filtering material. The exhaust valve(s) 8 is (are) configured to block off the central part of the mask, so that no air flow can pass during an inspiration.

The air exhaled by the user is filtered by the filtering material 6 of the central cartridge 7 then evacuated by the exhaust valve 8 which lets the air pass in this direction of flow circulation. Due to the very good seal obtained by the lip 32, no air leak is present between the mask 1 and the user. Thus, the filtration cartridges 5, 7 constitute the only filtration barrier between the respiratory tract of the user and the external environment.

The snap-on attachment of a side filter cartridge 5 is shown in more detail in . The body 50 of the cartridge 5 is provided with a continuous groove 500 on its periphery which, on inserting the cartridge 5 into the side opening 32 of the casing 3, snaps into a continuous bead 300 made on a periphery of the latter. This assembly is easy, fast and guarantees a tight fixing.

The snap-fastening of a central filter cartridge 7 is carried out in an analogous manner, as shown in more detail in . The body 70 of the central cartridge 7 is provided with a continuous bead 700 on its periphery which, on inserting the cartridge 7 into the central opening 33 of the casing 3, snaps into a continuous groove 301 performed on a periphery of the latter. We note on this that the central cartridge 7 is not made with a housing and a support for maintaining and sealing as for a side cartridge 5. The sealing at the level of the body 70 of the cartridge 7 is much less critical than for a side cartridge 5 because its operation is not permanent. The exhaust valve or valves 8 prohibit(s) the passage of the air inspired by this cartridge 7.

An advantageous embodiment of a silicone exhaust valve 8 is shown in . The valve 8 consists of a flexible blade 80 extended by a pin 81. The blade 80 is kept inserted in the frame 2 with the pin 81 mounted in a through hole 210 of the frame. When the user of the mask exhales air, the blade 80 is deflected and thus disengages the stud 81 from the hole 210, which allows the exhaled air to pass. On the contrary, during an inspiration of air, the blade 80 is deflected by closing the hole 210 by the pin 81.

By optimizing the shape of the valve 8 and its arrangement in the frame, it can be configured to amplify the sounds of the user's speech.

The mask 1 is held on the user's head by one or two elastic bands 9, each forming a fastening strap, as illustrated in the . For the attachment of a strap 9 to the frame 2, each strap 9 is pierced with at least a hole 90 at each end in which is housed a lug 22 projecting outwards, formed integrally in the frame. 2. Preferably, each side edge of the frame 2 comprises two lugs 22 spaced apart from each other. These two lugs 22 form points of traction for a strap 9 on the frame on each side edge. This arrangement allows a well-distributed traction and therefore a uniform pressure between the periphery of the sealing lip 31 and the wearer's face, which further reduces the risk of creating an air passage between the envelope 3 and face.

When the environment requires eye protection, a visor 10 can be fixed by snapping onto the frame 2. To do this, as visible on the , the armature 2 comprises at least two tabs 200 which are individually snapped into at least two notches 100 of the armature 2. Preferably, to guarantee optimum support, a number of three tabs 200 are provided, one of which is on each of the edges side and one arranged in the median plane of the mask. Like the wall 4, the visor 10 is made of polycarbonate (PC) or poly (methyl methacrylate) (PMMA). For aesthetic reasons, the visor 10 is curved, and preferably in the form of a spherical portion of the same radius or homothetic to that of the wall 4.

To individually identify each mask 1, it is possible to fix on the frame 2 at least one identification plate 11 on which are engraved at least one alphanumeric and/or bar code. This plate 11 is for example made of aluminum and preferably arranged inside the mask so as not to be visible from the outside as shown in .

Also, in the event of required traceability, at least one radio-identification tag (RFID) and/or at least one electronic wireless communication chip 12, 13 of the wifi or Bluetooth® type can be housed in housings afferents made in the frame.

It is easy to regularly clean the surfaces of the components of the mask 1 without however cleaning the filter cartridges 5 which, in particular with pellets 6 of sintered ceramic, have a very long service life.

Thus, after a certain number of uses, the user can dismantle all the filter cartridges 5, 7 by unclipping. Then, the mask subassembly consisting of the frame 2, the envelope 3 and of the transparent wall 4 can be cleaned in particular in a dishwasher. If necessary, the elastic strap or straps 9 can be removed before placing the aforementioned subassembly in the dishwasher.

Depending on the recommendations and/or the more or less severe constraints of the environment(s) encountered during the use of the mask 1, the replacement of the filtration cartridges 5, 7 can be carried out easily by any user.

Another example of a mask 1 according to the invention is illustrated in FIGS. 23 and 24. Here, a single lateral filtration cartridge 5 is fixed in the envelope 3. The principle of filtration remains the same as that previously indicated: the air breathed in by the user passes only through the single lateral cartridge 5, the valve 8 keeping the central opening 210 closed, and the exhaled air is expelled by the latter by crossing the central cartridge 7.

Of course, the invention is not limited to the examples of implementation which have just been described.

Other variants and improvements can be considered without departing from the scope of the invention.

In particular, it is possible to consider implanting a single filtration cartridge through which both the air inspired and that expired by the user of the mask would pass. Such an embodiment can for example be envisaged for environments that are not very restrictive in terms of particles, gases, viruses or bacteria to be filtered.

Also, in the examples shown, for aesthetic reasons, the side and front cartridges are arranged to leave the largest visible area of the mouth and around it. It is of course possible to provide other arrangements in the mask, in particular for applications where lip reading is not essential and/or in dusty work environments where the flow of aerosol carrying contaminated material mainly reaches the front of the mask.

If the nature of the filtering materials imposed by the level of filtration sought generates excessive pressure drops through the filtration cartridge(s), it is possible to consider installing a fan within the mask to compensate for said pressure drops.

If in the examples illustrated, the interface wall and the visor are preferably transparent while being colorless, it is possible to consider tinting one and/or the other in the mass while keeping them transparent. It can be a plastic material dyed in the mass.

It is also possible to envisage coating the transparent interface wall and/or the visor with a thin-film coating with a reflective function.

In general, any modification of a purely colorless material of the interface wall and/or of the visor can be considered. This may, for example, be the case when looking for sun protection for the face, in particular for the eyes, and/or cooling of the mask.

Claims (13)

Filtration cartridge (5, 5', 5''), intended to be removably attached to a health protection mask (1), comprising:

• a body extending along a longitudinal axis (X), the body being in two parts (51, 52) assembled to one another defining a housing, each of the two parts being pierced with at least one through hole opening into the dwelling;
• at least one part in the form of a pellet (6) having a total porosity greater than 40%;
• an elastomeric sealing ring (53) of substantially U-shaped cross-section within which the pellet is held, the ring being housed in the housing of the body and being held snugly against an interior portion of one and/or the other part of the body.

Cartridge (5, 5', 5'') according to claim 1, the pellet being made of sintered ceramic. Cartridge (5, 5', 5'') according to Claim 1 or 2, the two parts of the body being press-fitted one into the other. Cartridge (5, 5', 5'') according to one of Claims 1 to 3, the inner portion comprising at least one annular shoulder against which the sealing ring abuts directly or indirectly via a spacer. Cartridge (5, 5', 5'') according to one of the preceding claims, the sealing ring comprising at least one peripheral sealing lip in direct contact with the inner portion. Cartridge (5, 5', 5'') according to one of the preceding claims, the sealing ring comprising, at the bottom of the U, at least one clearance groove adapted to create an empty space between the ring and the corners of the pad. Cartridge (5, 5', 5'') according to one of the preceding claims, the elastomer of the ring being a silicone. Cartridge (5, 5', 5'') according to one of the preceding claims, comprising at least one mechanical protection grid (54) for the pellet, the grid bearing axially against an axial face of the ring of sealing and held inside in the housing of the body. Cartridge (5, 5', 5'') according to claim 8, comprising two protective grids each arranged on either side of the ring against one of its axial faces. Cartridge (5, 5', 5'') according to one of the preceding claims, one and/or the other of the parts of the body being colored with a color defined according to a code according to the level of filtration of the tablet, by example of the FMP1, FMP2 or even FMP3 type. Cartridge (5, 5', 5'') according to one of the preceding claims, one and/or the other of the parts of the body forming a cage of curved shape towards the outside. Cartridge (5, 5', 5'') according to one of the preceding claims, at least one of the two parts being pierced with a plurality of through holes of different diameters, preferably distributed in concentric circles. Method for producing a filtration cartridge (5, 5', 5'') according to one of the preceding claims, comprising the following steps:

• production by stamping of each of the two parts of the body;
• positioning with maintenance by adjustment of the sealing ring around a pad (6), preferably made of sintered ceramic;
• housing with abutment of the sealing ring sub-assembly around the pellet in an annular portion of one of the two parts of the body, where appropriate with the interposition of a spacer;
• force fitting of one of the two parts into the other of the two parts of the body.