ROUND FILTER ELEMENT FOR FILTRATION OF A GAS-FORMED FLUID

Description

Technical field

[0001] The invention relates to a circular filter element for the filtration of a gaseous fluid, comprising a particle filter medium body designed as a hollow body for particle filtration and a separate, hollow-body pollutant filter medium body for pollutant filtration according to the preamble of claim 1. State of the art

[0002] German patent application DE 10 2018 215 603 A1 describes a modular filter element comprising a first, raw air-side filter module and a second, downstream filter module, each hollow and cylindrical and arranged concentrically. This modular filter element can be used as a fuel cell air filter for air filtration in fuel cell applications. The first, raw air-side filter module separates particles, while the second filter module contains an adsorption medium for separating pollutants. Each filter module has a flow-tight end plate on its opposite end faces. The modular filter element, comprising the two filter modules, is housed in a casing that can be closed with a lid.

[0003] Combined hollow cylindrical air filter elements are known from utility model DE 20 2019 002 835 U1, publication WO 2010 / 074922 A1 and the subsequently published document WO 2022 / 194544 A1. Disclosure of the invention

[0004] The invention is based on the objective of designing a circular filter element for the filtration of a gaseous fluid with two filter medium bodies arranged one behind the other in the direction of flow in such a way that a high filtration performance is ensured over a long operating period.

[0005] This problem is solved according to the invention by the features of claim 1. The dependent claims specify advantageous further developments.

[0006] The circular filter element according to the invention serves for the filtration of a gaseous fluid, for example, air, and can be used, for example, in a fuel cell. The circular filter element comprises a particle filter medium body, which is designed as a hollow body and through which particles are separated from the gaseous fluid. The circular filter element further comprises a pollutant gas filter medium body for pollutant gas filtration, which is also designed as a hollow body and arranged concentrically to the particle filter medium body. The two filter medium bodies enclose a common, internal flow chamber. Each filter medium body is provided on both opposite end faces with an end plate, which covers the respective filter medium body at its end face in a flow-tight manner.

[0007] The flow through the circular filter element occurs either radially from the inside out or conversely radially from the outside in, with the term "radial" referring to the longitudinal axis of the circular filter element. In radial flow from the inside out, the untreated raw fluid is first directed into the inner flow chamber, from which the radial flow through the filter medium body proceeds from the inside out. In radial flow from the outside in, the treated fluid is collected in the inner flow chamber and discharged axially from it.

[0008] The filter media bodies can have, for example, a hollow cylindrical shape or a conical shape. Along their axial length – relative to the longitudinal axis of the circular filter element – ​​the filter media bodies can have either a constant cross-sectional area or a changing cross-sectional area, for example, a constantly increasing cross-sectional area. In a plane perpendicular to the longitudinal axis, the filter media bodies can have a circular, oval, or elongated cross-sectional shape, for example, stadium-shaped with semicircular narrow sides and straight long sides, where the long sides may optionally be convex or concave.

[0009] Each filter medium body has its own end discs; the end discs of the two filter medium bodies are not a single piece. To prevent air leakage between the filter medium bodies, a separately formed, flow-tight connecting element is attached to each end disc. This connecting element engages an end disc of the adjacent filter medium body, thus creating a flow-tight connection. The connecting element also fixes the relative position of the two filter medium bodies to each other.

[0010] The connecting element is not a housing component, but rather an integral part of the circular filter element and forms a structural unit together with the two filter media bodies. The circular filter element, including the connecting element, can be inserted into a filter housing, with the filter housing and circular filter element together forming a filter unit.

[0011] The connecting element is, for example, made of a plastic component. By bridging the gap between the filter media bodies in the area of ​​the end discs, the connecting element seals the annular space located between the filter media bodies in a flow-tight manner, thus preventing unwanted air currents between the raw and clean sides.

[0012] The connecting element is ring-shaped. It is separate from the end discs of the filter medium bodies but firmly connected to one of them. This is achieved, for example, by forming the end disc as a single casting made of a preferably soft-elastic material, which is cast onto the end face of the filter medium body. Simultaneously, a section of the connecting element projects into the end disc material, and during curing, a strong bond is created between the end disc and the connecting element. Suitable end disc materials include, for example, polyurethane or other plastics.

[0013] In an advantageous embodiment, a section of the connecting element projects into the space between the two filter media bodies and rests laterally against the end plate of the adjacent filter media body. This section of the connecting element ensures, firstly, a constant radial relative distance between the two filter media bodies. Secondly, this section enables a sealing connection with the end plate of the adjacent filter media body, for example, by ensuring that this end plate is in direct contact with the section of the connecting element. This ensures that no airflow can escape axially from the space between the two filter media bodies, but rather that the fluid is forced to flow radially through the second filter media body.

[0014] According to yet another advantageous embodiment, a section of the connecting element rests laterally against the end plate of the adjacent filter medium body on the side facing away from the supporting filter medium body. An additional sealing point also exists at this section of the connecting element, as the end plate of the adjacent filter medium body is in contact with this section of the connecting element. Further axial contact can exist between the end plate of the adjacent filter medium body and the overlapping part of the connecting element.In this way, up to three sealing points can be created between the end disc of the adjacent filter medium body (which does not support the connecting element) and the connecting element: firstly, via the section of the connecting element projecting between the two filter medium bodies and the end disc, which constitutes a radial seal; secondly, between the outer section of the connecting element and the end disc, which also constitutes a radial seal; and finally, axially between the end disc and the overlapping part of the connecting element, which constitutes an axial seal. This enables tolerance compensation and a reliable seal.

[0015] It is also advantageous that the two lateral sections of the connecting element form a receiving space for the end plate of the non-retaining filter medium body, so that this filter medium body, including its end plate, can be pushed into the receptacle on the connecting element, thereby immediately creating a sealing connection. This allows for easy assembly of the circular filter element.

[0016] According to yet another advantageous embodiment, a further section of the connecting element carries a sealing element that can be supported against a housing part. The sealing element can be inserted into a receiving groove formed on the section of the connecting element, with the portion of the sealing element protruding from the receiving groove bearing against the housing part and thus creating a flow-tight connection between the connecting element and the housing part. This embodiment has the advantage that, for example, a flow-tight seal can be created between a housing pot and the connecting element, so that the fluid on the clean side is forced to use the designated outflow channel in the filter housing for drainage. Preferably, the receiving groove is open axially downwards or upwards, so that the inserted sealing element seals in the axial direction.The seal can be positioned between the housing pot and a cover to be fitted onto it, so that the contact pressure for the seal is applied by the locking elements connecting the two housing parts. In this design, the connection between the housing pot and the cover to be fitted onto it does not necessarily have to be flow-tight.

[0017] According to an advantageous embodiment, a support structure, in particular a support grid, is arranged on at least one filter medium body. The support structure has a plurality of flow openings for the medium to be cleaned and simultaneously stabilizes the filter medium body. The support structure is preferably arranged on the downstream side of the pollutant gas filter medium body and / or the particle filter medium body.

[0018] According to a further advantageous embodiment, the connecting element is connected to a support grid arranged on a wall side of a filter medium body. The support grid is preferably located on the outer wall side of the radially inner filter medium body, this wall side preferably also forming the outflow side of the filter medium body. The support grid supports the immediately adjacent filter medium body in the radial direction. The support grid is particularly firmly connected to the axially opposite end plates of the filter medium body by means of a section of the support grid projecting into the material of the respective end plate. The support grid can be formed integrally with the connecting element, with the support grid extending along a wall side of the filter medium body and the connecting element extending radially outward essentially along the axial end face of the adjacent, radially outer filter medium body.

[0019] According to yet another advantageous embodiment, one or both filter medium bodies are designed as a filter bellows with a plurality of filter pleats. Alternatively, it is also possible to manufacture one or both filter medium bodies from a block-shaped material or from a wound filter medium.

[0020] According to yet another advantageous embodiment, a media layer, in particular a nonwoven layer, is arranged on the wall side of a filter medium body. The media layer reduces the friction between the filter medium body and an adjacent component, in particular a support grid that supports the filter medium body. Due to the reduced friction, deformation of the filter medium body in the event of relative movements, for example by vibrations or impacts, is prevented.

[0021] The nonwoven layer is located either between the two filter medium bodies and / or on the outer surface of a filter medium body, advantageously being arranged in each case between a support grid and the wall side of the filter medium body. It is advantageous for a nonwoven layer to be arranged downstream of the pollutant gas filter medium body so that particles carried out of the filter medium, for example activated carbon particles, are retained.

[0022] According to a particularly advantageous embodiment for filter elements of great length, at least one of the filter medium bodies consists of at least two sub-bodies joined together in the axial direction. The sub-bodies can, for example, be glued together.

[0023] The invention further relates to a filter device comprising a previously described circular filter element and a filter housing for receiving the circular filter element. The filter device can be used in or on a fuel cell, for example in the supply area of ​​the ambient air that is to be supplied to a fuel cell in order to subject the ambient air to filtration. Brief description of the drawings

[0024] Further advantages and practical designs can be found in the additional requirements, the figure description, and the drawings. These show: Fig. 1a a schematic section through a filter device with a circular filter element in a filter housing, Fig. 1b detail Ib from Fig. 1a in enlarged view, Fig. 1c, detail Ic from Fig. 1a in enlarged view, Fig. 1 a perspective view of the circular filter element, partially in section, Fig. 2 a Fig. 1acorresponding representation of a filter device with a round filter element in a further embodiment, Fig. 2b, detail IIb from Fig. 2a in enlarged view, Fig. 2c, detail IIc from Fig. 2a in enlarged view, Fig. 3a Fig. 1a corresponding illustration of a filter device with a circular filter element in yet another embodiment, Fig. 3b, detail IIIb from Fig. 3a in enlarged view, Fig. 3c, detail IIIc from Fig. 3a in enlarged view.

[0025] In the figures, identical components are labelled with the same reference symbols. embodiment(s) of the invention

[0026] In Figs. 1a to 1d A filter device 1 with a first circular filter element 2 for filtering a gaseous fluid is shown. The filter device 1 has a longitudinal axis 10, wherein Fig. 1 - and likewise Fig. 2- only the left half of the section on one side of the longitudinal axis 10 is shown. The filter device 1 is used, for example, to filter the fresh air supplied to a fuel cell.

[0027] The circular filter element 2 has two filter medium bodies 3 and 4, configured as a particle filter medium body 3 for filtering particles and as a pollutant filter medium body 4 for filtering pollutant gases such as sulfur dioxide, nitrogen oxides, or ammonia. The two filter medium bodies 3 and 4 are preferably designed as a filter bellows made of zigzag-folded filter medium. The pollutant filter medium body 4 can contain activated carbon to adsorb the pollutant gases as desired. Preferably, activated carbon particles are embedded in the filter medium of the pollutant filter medium body 4. The filter medium bodies 3 and 4 are, for example, conical in shape and have an elongated, flat-oval cross-sectional shape with two parallel longitudinal sides and two convex narrow sides.The two filter medium bodies 3 and 4 are arranged concentrically to each other and enclose an internal flow space 11, which receives the unpurified raw fluid and from which the two filter medium bodies 3 and 4 are radially flowed through from the inside out - with reference to the longitudinal axis 10.

[0028] The circular filter element 2 is housed in a filter housing 5, which comprises a housing pot 6 and a housing cover 7. An inlet 8 is formed on the housing cover 7, through which the uncleaned raw fluid is introduced and fed into the internal flow chamber 11. An outlet 9 is formed on the housing pot 7, through which the cleaned fluid is discharged. After passing through the two filter media bodies 3 and 4, the cleaned fluid collects on the outside of the surrounding, rearward-facing, pollutant gas filter media body 4. The inner side of the particle filter media body 3 forms the raw or inflow side, and the outer side of the pollutant gas filter media body 4 forms the clean or outflow side.

[0029] Each filter medium body 3, 4 is provided on both axially opposite end faces with an end plate 12, 13 or 14, 15, which covers the respective axial end face in a flow-tight manner. The end plates 12 to 15 may be cast onto the filter medium bodies. The lower end plate 12 of the particle filter medium body 3, which faces the bottom of the housing pot 6, is designed as a continuous plate and has no recess. In contrast, the upper end plate 13 of the same particle filter medium body 3 is annular with a central recess through which the raw air can flow via the inlet 8 into the inner flow chamber 11.

[0030] The upper end disc 15 of the pollutant gas filter medium body 4 is also ring-shaped. The lower end disc 14 of the pollutant gas filter medium body 4 is closed and consists of two parts: a soft, foamed plastic covering the end face of the filter medium body 4 and a plastic disc covering the opening to the interior, which is embedded in the foamed plastic material. As described below, the plastic disc can be a section 18a of a support grid 18. Alternatively, the lower end disc 14 can be made in one piece from a foamed plastic.

[0031] A first, flow-tight connecting element 16 is located on the upper end disk 13 of the particle filter medium body 3, which faces the housing cover 7. This connecting element projects radially outwards and is annular in shape. A section of the connecting element 16 is embedded in the material of the upper end disk and thus firmly connected to the end disk 13. The connecting element 16 overlaps the upper end disk 15 of the adjacent, radially more outwardly located pollutant filter medium body 4, thereby establishing a flow-tight connection between the end disk 15 and the connecting element 16. A first section 16a of the connecting element 16 projects axially inwards from the radially extending portion into the space between the two filter medium bodies 3, 4.A second section 16b projects axially downwards on the radially outer side of the upper end disk 15, so that the two sections 16a and 16b form an annular receptacle for the upper end disk 15 of the pollutant gas filter medium body 4, into which the upper end disk 15 can be inserted. Sealing points are formed on the radially inner and radially outer sides of the end disk 15 with the connecting element 16 and sections 16a and 16b, respectively. Alternatively or additionally, a sealing point is formed between the axial end face of the end disk 15 and the connecting element 16. In principle, the formation of one of the three sealing points is sufficient. The connecting element 16 is designed to be flow-tight, ensuring a flow-tight connection with the upper end disk 15 and preventing the axial outward flow of the fluid located in the space between the filter medium bodies 3 and 4.

[0032] A support grid 18 is arranged on an outer wall or shell side of the corrosive gas filter medium body 4. This support grid 18 surrounds the corrosive gas filter medium body 4 on the outside and is embedded and held in place at its ends by the material of the end discs 14, 15. A sealing carrier 17 is integrally connected to the support grid 18. This carrier is designed as a circumferential, radially outwardly projecting collar with an axially downwardly open receiving groove 17a for a sealing element 19. The sealing element 19 can be inserted into the receiving groove 17a in the form of a sealing ring. Alternatively, a sealing element can be injection-molded. The sealing element 19 rests on a shoulder of the housing pot 6 and seals the raw side against the clean side.

[0033] A layer of media, for example a nonwoven layer, can be located between the support grid 18, which has a multitude of flow openings, and the outer shell of the pollutant gas filter medium body 4. This provides mechanical protection against friction and, in particular, retains activated carbon particles that may escape from the pollutant gas filter medium body 4.

[0034] A section of the support grid 18 extends radially inwards into the lower end disk 14 as section 18a, wherein section 18a is formed radially within the filter medium as a closed, flow-tight disk. The lower end disk 12 of the particle filter medium body 3 is axially supported by section 18a. As shown in Fig. 1cAs can be seen, section 18a can have an annular section which extends axially into the interior of the pollutant gas filter medium body 4. The inner particle filter medium body 3 is radially supported on this rib by the lower end disk 12.

[0035] When the inner particle filter medium body 3 is inserted into the outer pollutant gas filter medium body 4, the two filter medium bodies 3 and 4 are thus tightly connected to each other via the at least one sealing point between the upper end disc 15 of the outer filter medium body 4 and the connecting element 16. A sealing point is also formed between the circular filter element 2 and the filter housing 5. In the area of ​​the raw fluid inlet 8, the upper end disc 13 of the inner filter medium body 3 preferably rests axially against the housing cover 7 without sealing. The sealing point between the raw side and the clean side is located radially outside and is formed as an axial seal by the sealing element 19, which is mounted on the outer filter medium body 4, bearing against a collar of the housing pot 6.

[0036] Fig. 1dFigure 1 shows a perspective view of the circular filter element 2 with the outer pollutant gas filter medium body 4 and the inner particle filter medium body 3 contained therein. The connecting element 16, which is connected to the upper end disk 13 of the inner particle filter medium body 3, forms a radially outwardly projecting wall section with an inner, axially downwardly extending section 16a and an outer, also axially downwardly extending section 16b, thereby forming a U-shaped recess for gripping the upper end disk 15 of the outer pollutant gas filter medium body 4.

[0037] The upper end plate 15 of the outer pollutant gas filter medium body 4 connects the support grid 18 to the sealing carrier 17, which has the receiving groove 17a for the sealing element 19.

[0038] The pollutant gas filter medium body 4 and the particle filter medium body 3 can thus be easily connected to form a single unit and inserted into the housing. Conversely, the two filter medium bodies 3 and 4 can be easily separated again. This makes it possible, for example, to replace only one of the two filter medium bodies 3 and 4 with a new one if their service life differs, while continuing to use the other. Compared to a one-piece design, no additional seal is required, as the end disc 15 of the outer filter medium body 4 is used for sealing.

[0039] In the Figs. 2a to 2c Another embodiment is shown, which basically has the same structure as the first embodiment, so reference is made to the preceding description. The same applies to the Figs. 2a to 2cThe filter device comprises a circular filter element 2, which includes a particle filter medium body 3 and an surrounding pollutant gas filter medium body 4, enclosing an internal flow chamber 11. The fluid to be cleaned flows radially through the filter medium bodies 3 and 4 from the inside out.

[0040] Unlike the Figs. 1a to 1d is at Figs. 2a to 2c No support grid is arranged on the outer wall or casing side of the pollutant gas filter medium body 4. However, a support grid 18 is located in the space between the filter medium bodies 3 and 4 and is associated with the particle filter medium body 3. A layer of nonwoven fabric may be located between the support grid 18 and the adjacent side surface of the particle filter medium body 3.

[0041] The support grid 18 can be formed in one piece with a connecting element 16, which is firmly connected to the upper end disk 13 of the particle filter medium body 3, for example, embedded in it. A section 16a of the connecting element 16 projects axially between the filter medium bodies 3 and 4 in the direction of the space between them and forms a radial sealing point with the upper end disk 15 of the pollutant gas filter medium body 4. A second section 16b projects radially downwards in the outer direction and forms another radial sealing point with the upper end disk 15. Additionally or alternatively, the axial end face of the upper end disk 15 forms a sealing point with the radially extending part of the connecting element 16.

[0042] The upper end disk 15 of the pollutant gas filter medium body 4 has an upper shoulder on its radially inner side, against the vertical side of which the section 16a of the connecting element 16 rests. The upper end disk 13 of the inner particle filter medium body 3 projects into the shoulder in the upper end disk 15. The upper end disk 15 of the pollutant gas filter medium body 4 rests radially against the support grid 18 of the particle filter medium body 3. The support grid 18 can be closed in this area and thus form a contact rib for the upper end disk 15 of the pollutant gas filter medium body 4, thereby creating an additional sealing point.

[0043] The radially outer section 16b of the connecting element 16 also has a receiving groove into which a sealing element 19 is inserted, which is supported against a shoulder of the housing pot 6. The connecting element 16 thus simultaneously forms the seal carrier for the sealing element 19.

[0044] The lower end disc 14 is designed as a continuous disc. An axially downward-pointing, hollow cylindrical dome is formed on the lower end disc 14, which is positively engaged in an annular recess at the bottom of the housing, thus securely holding the round filter element 2. The lower end disc 14 is preferably made of a flexible material, for example, polyurethane foam.

[0045] The connecting element 16 and the support grid 18 form a single, continuous component which continues in section 18a in the area of ​​the lower end disk 12 of the particle filter medium body 3. This section 18a of the support grid 18 is disc-shaped and at least partially enclosed by the material of the lower end disk 12, so that a firm connection with the lower end disk 12 exists. The disc-shaped section 18a is at least partially flow-tight and prevents an excess airflow of the raw fluid from the internal flow chamber 11 bypassing the particle filter medium body 3 and reaching the pollutant gas filter medium body 4.

[0046] The in the Figs. 3a to 3c The illustrated embodiment largely corresponds to the embodiment according to the Figs. 2a to 2c . At Figs. 3a to 3cHowever, the upper end disk 15 of the outer pollutant gas filter medium body 4 has a substantially rectangular cross-sectional shape with respect to the depicted sectional plane containing the longitudinal axis, as does the upper end disk 13 of the particle filter medium body 3, which is offset radially inwards relative to the end disk 15. The upper end disk 15 of the outer pollutant gas filter medium body 4 therefore has no step. Section 16a of the connecting element 16 is located between the end disks 13 and 15 and rests against the radial outer surface of the end disk 13 and the radial inner surface of the end disk 15. Furthermore, in this embodiment, both the inner particle filter medium body 3 and the outer pollutant gas filter medium body 4 have a support grid 18. The radially outer support grid 18 of the pollutant gas filter medium body 4 has the sealing carrier 17.Alternatively, the sealing carrier 17 can also be formed by an axially extended radially outer section 16b of the connecting element 16.

[0047] The lower end disk 14 of the outer pollutant gas filter medium body 4 is essentially flat, as in the first embodiment. However, the lower end disk 14 could also be made of a different material, as in the first embodiment. Fig. 2a be trained.

Claims

1. A round filter element for filtering a gaseous fluid, with a particle filter medium body (3) designed as a hollow body for particle filtration of the gaseous fluid and with a separate harmful gas filter medium body (4) designed as a hollow body for harmful gas filtration, which is disposed concentrically to the particle filter medium body (3), wherein the two filter medium bodies (3, 4) enclose an internal flow chamber (11), wherein each filter medium body (3, 4) features an end disc (12, 13, 14, 15) on each of its opposite front faces, wherein the upper end discs (13, 15) are each annular and the lower end discs (12, 14) are each closed, characterized in that a flow-tight, separately formed connecting element (16) is connected to the annular end disc (13) of the radially inner filter medium body (3), which connecting element projects radially outward and is annularly circumferential, and which surrounds the annular end disc (15) of the adjacent radially outer filter medium body (4) and establishes a flow-tight connection with the end disc (15) of the adjacent filter medium body (4).

2. The round filter element according to claim 1, characterized in that a section (16a) of the connecting element (16) protrudes into the intermediate space between the two filter medium bodies (3, 4) and rests laterally against the end disc (15) of the adjacent filter medium body (4).

3. The round filter element according to claim 1 or 2, characterized in that a section (16b) of the connecting element (16) on the side facing away from the holding filter medium body (3) rests laterally against the end disc (15) of the adjacent filter medium body (4).

4. The round filter element according to one of the claims 1 to 3, characterized in that a section (16b) of the connecting element (16) is the carrier of a sealing element (19) for supporting a housing part (6).

5. The round filter element according to one of the claims 1 to 4, characterized in that the connecting element (16) is connected to a support grid (18) arranged on a wall side of a filter medium body (4).

6. The round filter element according to one of the claims 1 to 5, characterized in that at least one filter medium body (3, 4), preferably both filter medium bodies (3, 4), are designed as filter bellows.

7. The round filter element according to one of the claims 1 to 6, characterized in that a media layer, in particular a non-woven layer, is arranged on the wall side of a filter medium body (3, 4).

8. The round filter element according to claim 7, characterized in that the media layer is disposed between the two filter medium bodies (3, 4).

9. The round filter element according to claim 7 or 8, characterized in that the media layer is disposed on the exterior side of a filter medium body (4).

10. The round filter element according to one of the preceding claims, characterized in that at least one of the filter medium bodies (3, 4) consists of at least two partial bodies which are joined together in the axial direction.

11. A filter device with a round filter element (2) according to one of the claims 1 to 10 and with a filter housing (5) for receiving the round filter element (2).

12. A use of a filter device according to claim 11 in or on a fuel cell.