Filtering unit with adsorbent bed with differentiated thickness
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- GVS FILTER TECHNOLOGY UK LTD
- Filing Date
- 2024-06-17
- Publication Date
- 2026-05-13
AI Technical Summary
Existing filtering units for respiratory protective devices are bulky and heavy due to the constant thickness of the adsorbent bed, which compromises user comfort and requires excessive plastic material, while also not optimizing filtering capacity effectively.
A filtering unit with an adsorbent bed of varying thickness, where the central area has a greater thickness for higher airflow regions and a lesser thickness for lower airflow regions, allowing for a more compact design and reduced plastic usage, achieved by using a casing with graduated compartments and permeable non-woven sheets to distribute air evenly.
The solution results in a more compact filtering unit with improved gas performance and reduced plastic material usage, maintaining the same overall dimensions and filtering capacity without increasing the unit's size, enhancing user comfort and safety.
Smart Images
Figure IB2024055890_09012025_PF_FP_ABST
Abstract
Description
[0001] FILTERING UNIT WITH ADSORBENT BED WITH DIFFERENTIATED
[0002] THICKNESS
[0003] The present invention relates to a filtering unit according to the preamble of the main claim .
[0004] Various embodiments of filtering units are known, for example for full-face masks , half-face masks or other respiratory protective devices which are adapted to filter the inhaled air of a user wearing such a device .
[0005] In particular, the present invention relates to a gas and particulate filtering unit comprising a casing containing a bed of adsorbent material, a particulate filter, for example a pleated one, being arranged on said casing and externally thereto . The bed made of an adsorbent material is generally obtained by using at least one of an activated carbon, alumina, zeolite, silica, a catalyst ( such as goldbased catalyst capable of removing CO) or combinations thereof .
[0006] In order to contain this "adsorbent bed" , the casing comprises two parts or shells defining a cavity inside the casing . Openings are provided in said parts for the passage of air through the casing .
[0007] The adsorbent bed is introduced into the cavity, usually in granular form, for example by means of an angled hopper which is made to vibrate and from which the granules pass into the cavity or by means of the " snowstorm" technique . In the cavity, the granules are compacted so as to perform their function of filtering the air which crosses them and passes through the openings of the two parts or shells of the casing .
[0008] The air comes to the aforesaid casing through the external, pleated filter and from openings provided within a cover of the aforesaid casing . In known solutions , the casing may take various shapes , often cylindrical or rectangular to suit the product form of the manufacturer and the connections to the respirator comprising said filtering unit . Furthermore, the cavity containing the adsorbent bed has a constant depth .
[0009] US2013 / 0298775 relates to a replaceable filter canister used with purifying respirators . In particular, this prior document relates to a replaceable filter canister shaped to conform to the face of a user .
[0010] This known kind of filter canister may be considered as conformal filter canister, which is different to the traditional flat outlet wall canister . Since some purchasers of respirators prefer the conformal filter canister while other purchasers prefer the traditional canisters , the suppliers have to make and inventory both types of canister .
[0011] The solution that the US patent application offers is a single filter assembly which may provide both planar and conformal filter canister functionality . This is obtained by coupling in a removable way a conformal filter canister with a connector piece which connects the canister to the respirator .
[0012] US2013 / 0298775 describes that the conformal filter has a body having an input end with a convex inlet wall and an output end with a concave outlet wall . These walls are in parallel, spaced-apart relationship joined by a peripheral outside wall to define an enclosed filter chamber in which filter elements (a particulate filter element and an adsorption filter bed) are retained .
[0013] Both the description and the drawings only describe that the filter chamber is defined by parallel input and output walls and the outside wall, and the drawings clearly only describe that the filter chamber has a continuous thickness or volume : the prior US document does not disclose or suggest that the thickness of the filter chamber changes (i . e . , it is not differentiated or graduated) in different portions of it : the thickness of the filter chamber is the same in any portion of said filter chamber, both where there is the greatest air flow between the inlet and outlet ends and in chamber portions which are on the side of the portion .
[0014] The prior document does not give any hint to the skilled person to have a filter chamber where the absorption filter bed has a graduated thickness i . e . different thicknesses in different portions of said filter chamber .
[0015] These known solutions therefore have a relatively high quantity of adsorbent material defining the corresponding adsorbent bed in order to have a suitable filtering capacity . This leads to relatively large filtering unit s with a consequent increase in weight and a reduction in the comfort of use of the respirator by a user .
[0016] The object of the present invention is to provide a filtering unit with a bed made of an adsorbent material which is improved with respect to known solutions .
[0017] In particular, the object of the present invention is to provide a filtering unit of the aforementioned type containing a volume of said adsorbent material which allows to optimize the filtering capacity of the unit ; all this without however increasing the overall dimensions of the filtering unit .
[0018] Another object is to provide a filtering unit of the cited type the production of which involves a reduced use of plastic material .
[0019] A further object is to provide a filtering unit which offers optimum comfort and safety of use to the user .
[0020] These and other objects are achieved by a filtering unit with an adsorbent bed according to the appended claims .
[0021] For a better understanding of the present invention, the following drawings are attached, purely by way of nonlimiting example, in which :
[0022] Figure 1 shows a top perspective view of a filtering unit according to the invention;
[0023] Figure 2 shows a perspective view of the filtering unit of Figure 1 in a position rotated by 180 ° ;
[0024] Figure 3 shows a partially exploded top perspective view of the filtering unit of Figure 1 ;
[0025] Figure 4 shows an exploded top perspective view of the filtering unit of Figure 1 ;
[0026] Figure 5 shows an exploded perspective view from below of the filtering unit of Figure 1 ;
[0027] Figure 6 shows a section according to line 6-6 of Figure 3 with some parts omitted for greater clarity; and
[0028] Figure 7 shows a section according to line 7-7 of Figure 3 with some parts omitted for greater clarity .
[0029] With reference to the cited figures , a filtering unit according to the invention is indicated as a whole with 1 . It comprises a casing 2 having two concave parts or shells 3 and 4 , coupled to each other and defining an inner cavity 6 ( inside the casing) .
[0030] A first part 3 of the parts or shells of the casing 2 has a body 8 having a transversal face 9, from the edge of which a wall 10 delimiting an internal compartment 11 projects . In the face 9 there is a through hole 13 opening in the compartment 11 on one side and within a seat 15 for a known per se valve member or diaphragm valve 16, on the other side . This valve is , as usual, a one-way non-return valve which is used to introduce filtered air ( from the filtering unit 1 ) into a full-face mask, or a half-face mask or similar respiratory device ( in general, respirator, not shown) to which the filtering unit 1 is adapted to be connected . The first part 3 of the casing has curved connection elements 17 suitable to connect to other existing components - strap connectors and exhalation valve cover - of the respirator . Moreover, sealing members are provided for constraining said unit to the respirator; said sealing members are the outer cylindrical face 15A of seat 15 and a channel 9A around the perimeter of face 9 ( see for example Fig . 2 ) .
[0031] The second part 4 of the casing (which acts as a cover for the first part 3 ) has a transversal face or wall 18 provided with openings 19 ( communicating with the inner cavity 6 ) between spokes 20 ; these members are connected to a central part 21 of said wall 18 and to an edge 22 of the latter . On both sides of this edge, opposite end walls 23 and 24 project : a first end wall 23 faces the first part 3 and is adapted to contact its wall 10 ; the second end part 24 rises from the face or wall 18 .
[0032] The latter delimits , with the first end wall 23 , a compartment 26 of the second part or cover 4 adapted to face the compartment 11 of the first part 3 of the casing; the compartments 26 and 11 define the cavity 6 with casing 2 assembled . This assembly takes place by binding the aforementioned walls 10 and 23 together in any known way, for example by ultrasonic welding, gluing, mechanical connection or other known method .
[0033] The second end wall 24 forms , with the face or wall 18 of the second part 4 of the casing, a seat 29 for the pleated filter 30 overmolded on TPE (that is for a particulate filter of equivalent characteristics such as filter P3 as recognized in EU with minimum efficiency 99, 95% or P100 filter as recognized in the US with minimum efficiency 99, 97% ) . This filter is per se known .
[0034] Above the casing 2 there is a cover 32 which closes over the pleated filter 30 and which is connected to the casing 2 in a manner per se known, for example by snap coupling between said components of the filtering unit 1 . The cover 32 has openings 33 for the passage of air .
[0035] The compartment 11 of the first part 3 of the casing 2 has , internally, a step 35 between an edge portion 36 adjacent to the wall 10 and a recessed internal part or portion 38 where the through hole 13 opens . In this way, the compartment 11 has a part that is the internal portion 38 which, along any plane passing through the hole 13 and containing the longitudinal axis W of said hole, has a depth measured along this plane parallel to said axis W which is greater than the depth of the compartment 11 at the edge portion 36 .
[0036] Compartment 11 has ribs 11K along its surface ( from edge portion 36 to the internal portion 38 ) .
[0037] Within the compartment 11 a sheet 40 (that will be considered further as " second sheet 40" ) of non-woven fabric is arranged which is placed in contact with the ribs 11K and welded ( for example by heat ) to said ribs . This sheet 40 is obviously permeable to allow the passage of the air . The sheet 40 is in contact with the ribs of the edge portion 36 and the internal portion 38 of compartment 11 and it follows the shape of this compartment .
[0038] A bed of adsorbent material 43 is placed on the sheet , adapted to filter the air passing from and towards the opening 13 . This adsorbent material is of a per se known type and can be : activated carbon, alumina, zeolite, silica, a catalyst or any combination thereof . The bed of adsorbent material 43 compacts on the sheet 40 during its introduction into the compartment 11 , which insertion takes place in any known motion ( such as for example by vibration from a hopper or with the " snowstorm" technique ) . Due to the fact that the sheet 40 lies on the portions 36 and 38 of compartment 11 , the bed of adsorbent material 43 fills in-depth portion 38 and portion 36 of compartment 11 . Due to the different depths of the two portions 36 and 38 , as it will be described in the following, a greater volume of adsorbent material 43 will be located in portion 38 than in portion 36 so that the thickness of said material in portion 38 is greater than the thickness of material in portion 36 .
[0039] Above the bed of adsorbent material 43 there is a further sheet 45 made of permeable non-woven fabric which is sealed (by heat , for example ) , inside the second part 4 , to the face or wall 18 of this second part 4 . Sheet 45 will be considered as " first sheet" since the air entering into the casing 2 first hits this sheet and then passes through the " second" sheet 40 .
[0040] This embodiment defines a plenum or empty space 11W on both sides of the absorbent bed, first between the first sheet 45 and the sunburst pattern of the second part 4 of the casing 2 , second between the second sheet 40 and the first part 3 of the casing 2 (as the sheet 40 is supported by the ribs 11K) ; in this way, the air flow coming from outside ( inhaled air, arrow Z in Figure 6 ) is distributed throughout the full surface area of the first sheet 45 , respectively through the full area of the adsorbent bed 43 and is drawn in using the full area of the second sheet 40 , respectively the full volume of the absorbent bed as the user inhales .
[0041] As above stated and as it can be seen from figure 5 and from figures 6 and 7 , the depth or thickness of adsorbent material of the bed 43 is different in different areas or parts of the inner cavity 6 : at a central part of this cavity 6 that is of the internal portion 38 of the compartment 11 of the first part 3 , the thickness of a portion or a central volume 49 of the bed of adsorbent material 43 is greater than the thicknes s of a portion or of the peripheral volume 50 of this bed 43 present at the edge 10 of this compartment that is the edge portion 36 of the compartment 11 . It follows that the adsorbent bed varies according to thicknes s within the inner cavity 6 : its volume is greater at the part or area ( 38 ) of the cavity 6 where there is greater air flow (between the hole 13 and the hole 19 ) and is lower ( 50 ) in the parts or areas of less airflow (on the sides of the inner cavity 6 ) . This volume gradually passes from the central volume 49 to the peripheral one 50 .
[0042] In other words , the adsorbent bed is "graduated" within the inner cavity 6 having different thicknesses measured parallel to the axis W passing from one side to the opposite side of this cavity (or of the wall 10 which delimits it ) . Purely by way of non-limiting example, the depth or thickness of the adsorbent bed or bed of adsorbent material 43 is approximately 20-21 mm if measured exactly along the W axis (central volume 49 ) , while it is approximately 10-11 mm if measured near the edge 10 parallel to the axis W (peripheral volume 50 ) .
[0043] Obviously, the values indicated above for the depth of the adsorbent bed 43 are wholly exemplifying but not limiting and may also depend on the shape of the parts 3 and 4 of the casing 2 and therefore on the shape of this casing .
[0044] It is however important to highlight the different depths ( in the example of portions 49 and 50 ) that is the different thicknesses of the adsorbent bed (measured parallel and / or along the axis W of the through hole 13 ) : in the part or area where there is the greatest breathing air of a user there is the greatest volume and thicknes s , while in its peripheral portion the volume or thicknes s of the adsorbent bed is least .
[0045] The folded shape should also be noted on two planes containing orthogonal axes X and Y of at least part 3 of the casing 2 and in this case also of the entire filtering unit 1 : this allows to conform this filtering unit to follow the contours of the user ' s face . This also keeps the filtering unit compact .
[0046] Furthermore, thanks to this conformation, the adsorbent bed placed between the sheets 40 and 45 is compact and these sheets can be easily coupled to the parts 3 and 4 of the casing 2 .
[0047] Thanks to the invention, the whole filtering unit 1 is more compact if compared to an equivalent filtering unit of the prior art .
[0048] As the filter is more compact , plastic material used to produce the casing 2 is saved as the plenum is reduced to minimum height following the case cavity 6 . Due to the maximum use of the inner space, the overall height is reduced .
[0049] Compared with filtering unit of the prior art where the thickness of the adsorbent bed is constant and having the same volume of the adsorbent material, the invention of graduated bed reduces the filter height by 3 . 0 mm and is using 15% less plastic material on the case ( 3 ) .
[0050] Moreover, the invention enables to significantly increase the size of the adsorbent media compartment , resulting in improvement in gas performance : all this without increasing the overall dimension, as above stated .
[0051] Purely as non-limiting example, the following table shows the features of a filtering unit , according to the invention, of overall height of 47 , 5 mm measured along axis W as compared to a corresponding filtering unit of the prior art .
[0052] The filtering group is made through the following steps : a) the parts 3 , 4 of the casing 2 and the cover 32 are made by moulding; b) the sheets 40 and 45 are connected, by hot welding or gluing, internally to the aforementioned parts 3 and 4 of the casing 2 ; c) the adsorbent material is introduced into the compartment 11 of the first part 3 of the casing 2 so as to create the adsorbent bed 43 . This material is introduced by vibration fall from a hopper or by a "snowstorm" ; d) the parts 3 and 4 are coupled, for example by ultrasonic welding; e ) the pleated filter 30 is inserted in the seat 29 of the second part 4 of the casing; and f ) the cover 32 of the casing 2 is coupled .
[0053] The filtering unit is thus prepared for use, in a respirator such as , for example, in a full-face mask or half- mask so as to provide a device for protecting the user ' s breathing . This device comprises a facepiece which covers at least the user ' s nose and mouth or optionally also his eyes and entire face . The device has suitable sealed connections to the filtering unit 1 .
[0054] A preferred embodiment of the invention has been described . Yet others are however possible for the person skilled in the art on the basis of what has been described so as to provide a filtering unit with the innovative characteristics described in the attached claims .
Claims
CLAIMS1. A filtering unit for gases and particulates usable in a respiratory protective device, said filtering unit (1) comprising a casing (2) having an inner cavity (6) containing a bed of adsorbent material (43) , a particulate filter (30) being externally associated with said casing (2) and inserted into a cover (32) of the filtering unit integral with said casing (2) , said cover being provided with at least one through opening (33) , the casing comprising two concave parts (3, 4) , connected to each other and delimiting the inner cavity (6) containing said bed of filtering material (43) , a first part (3) of the casing presenting a through hole (13) adapted to cooperate with a valve member (16) , the second part also having at least one through opening (19) at which the particulate filter (30) is placed, characterized in that the bed of adsorbent material has a differentiated thickness or volume, i.e. it is graduated inside different portions (36, 38) of the cavity (6) of said casing.
2. The filtering unit according to claim 1, characterized in that the thickness or volume of the bed of adsorbent material (43) is greater in a portion (38) of the cavity (6) of said casing where there is the greatest air flow between said hole (13) and said opening (19) of the parts (3, 4) of the casing.
3. The filtering unit according to claim 1, characterized in that a part (3) between said parts (3, 4) of the casing (2) comprises a compartment (11) of variable depth between a lower depth at an edge portion (36) and a greater depth at an internal portion (38) where there is a greater air flow between said hole (13) of the first part (3) of the casing and said at least one opening of the second part (4) of the casing, said compartment (11) being adapted to contain the bed of adsorbent material.
4. The filtering unit according to claim 3, characterized in that said part comprising the compartment (11) is the first part (3) of the casing (2) , the through hole (13) cooperating with the valve member (16) opening in said internal portion (38) of greater depth.
5. The filtering unit according to claim 3, characterized in that said compartment (11) is delimited by a transversal face (9) and by a wall (10) rising from an edge of said transversal face (9) , said wall (10) being adapted to cooperate with a wall (23) of the second part (4) of the casing protruding from a transverse face (18) of the latter, said transversal face (9) of said first part (3) of the casing having the through hole (13) and said transversal face (18) of said second part (4) having the at least one opening (19) of the latter.
6. The filtering unit according to claim 1, characterized in that the thickness or volume of the bed of adsorbent material (43) is measured along a longitudinal axis (W) of the hole (13) of the first casing part (3) or is measured parallel to that axis (W) on a plane containing said longitudinal axis.
7. The filtering unit according to claim 5, characterized in that at least the transversal face (9) of the first part (3) of the casing has a curved shape on two planes containing orthogonal axes (X, Y) .
8. The filtering unit according to claim 7, characterized in that it has an overall curved shape with respect to two orthogonal axes (X, Y) .
9. The filtering unit according to claim 1, characterized in that the bed of adsorbent material comprises at least one of activated carbon, zeolite, alumina, silica, a catalyst, or a combination thereof.
10. The filtering unit according to claim 1,characterized in that said bed of adsorbent material is contained between two sheets (40, 45) of non-woven fabric which are internally integral with said parts (3, 4) of the casing (1) , said constraint between said sheets and said parts being obtained preferably by hot welding, between each sheet (40, 45) and the corresponding part (3, 4) an empty space (11W) being provided.
11. The filtering unit according to claim 1, characterized in that said parts (3, 4) of the casing are fixed to each other preferably by ultrasonic welding.
12. The unit according to claim 1, characterized in that said bed of adsorbent material is compressed in the cavity (6) of the casing (2) .
13. A user's respiratory protective device such as a face mask or half-face mask or respirator, said device comprising a part covering at least the user's mouth and nose or optionally the user' s eyes and entire face, characterized in that said device comprises a filtering unit (1) according to the preceding claims.