Ring filter element and associated manufacturing process as well as suitable filter device

Abstract

Ring filter element (2) for filtering a liquid or gaseous medium, - with an annular filter body (9) made of a filter material (10) through which the medium can flow, and - with an annular inner frame (11) made of a supporting material, which is arranged concentrically in the filter body (9) and through which the medium can flow, - wherein the filter body (9) is supported directly or indirectly with its radially inner body inner side (14) on a radially outer, cylindrical frame outer side (17) when it is pressed against the inner frame (11) during a flow from radially outside to inside, - wherein the inner frame (11) has a support structure (12) with radial passage openings (13) through which the medium can flow, - wherein the ring filter element (2) has at least one ring-shaped or spiral-shaped holder (19) which surrounds the inner frame (11) and is arranged on the inside of the body (14), - wherein the holder (19) has an annular or spiral adhesive body (22) made of an adhesive, - wherein the adhesive body (22) is bonded radially outwardly directly to the filter body (9) by the adhesive of the adhesive body (22), characterized in that - that the adhesive penetrates at least partially into some of the through-openings (13) of the support structure (12), so that the holder (19) is fixed radially inwardly to the inner frame (11).

Description

[0001] The present invention relates to a ring filter element for filtering a liquid or gaseous medium according to the preamble of claim 1. The invention also relates to a method for producing such a ring filter element. Finally, the present invention also relates to a filter device equipped with such a ring filter element.

[0002] A conventional ring filter element, as known, for example, from US 9 868 083 B2, has an annular filter body made of a star-shaped folded filter material through which the medium can flow. Furthermore, the ring filter element has an annular, circumferentially closed inner frame made of a support material, which is arranged concentrically in the filter body and through which the medium can also flow. In such a ring filter element, the filtration function is performed by the filter body, i.e. not by the inner frame. The inner frame supports the filter body radially on the inside and thereby stabilizes the ring filter element when the medium to be cleaned flows through it radially from the outside to the inside during filtration. For this supporting function, the filter body rests radially with its radially inner body inner side against a radially outer, cylindrical frame outer side, at least during filtration operation.

[0003] During filtration, impurities accumulate on the outer upstream side of the filter body and increase the flow resistance of the filter body over time. To increase the service life of the filter element, it is known, for example from the above-mentioned US 9 868 083 B2, to carry out a backwash process in which, for example, filtered medium flows through the filter body in the opposite flow direction, i.e. radially from the inside to the outside. Such a regeneration process can be carried out at increased pressure and / or in a pulsed manner. Without additional protective measures, the filter material would lift off the inner frame during such a backwash process, which can lead to severe wear of the filter body, particularly in pulsed backwashing under increased pressure.To prevent such wear, the conventional ring filter element known from the aforementioned US Pat. No. 9,868,083 B2 is known to arrange several support rings on the radially outer side of the filter body, which hold the filter body in position against the inner frame. The support rings are attached to the filter body by means of an adhesive.

[0004] For certain filtration tasks, it may be undesirable to use such support rings. For example, the medium may be transporting a product that is separated from the medium flow with the help of the ring filter element so that it can be used again. The desired product thus accumulates on the upstream side, i.e. on the raw side of the filter body. Due to aging processes and the high mechanical stress, particles from the support rings can get into the product. Particularly in food production, for example in the manufacture of flour, or in the production of medicines, the admixture of particles from such support rings to the desired product must be avoided. The use of adhesives on the raw side is also undesirable in order to avoid contamination of the product with adhesive particles.

[0005] DE 697 36 548 T2 discloses a generic ring filter element that differs from the conventional ring filter element presented above in that it has several adhesive strips that surround the inner frame in a ring shape and are bonded radially outwardly directly to the filter body using adhesive. This results in improved positioning of the filter body on the inner frame.

[0006] A similar ring filter element is known from DE 12 53 236 A.

[0007] From DE 10 2020 200 903 A1 it is known to fix the filter body radially to the inner frame by means of an annular expansion body.

[0008] GB 1 255 894 A discloses another ring filter element whose inner frame has a longitudinal gap, i.e. is not closed in the circumferential direction. This inner frame has a plurality of radially projecting longitudinal webs on its outer side, which are distributed in the circumferential direction and between which channels are formed, at the bottom of which openings are formed through which the medium can flow through the inner frame. In this ring filter element, the filter body is designed as a tube made of unfolded filter material, closed on one side, which is pulled onto the inner frame. The filter body can be attached to the radially free-standing ends of the longitudinal webs by means of an adhesive.

[0009] The present invention addresses the problem of providing an improved embodiment for a ring filter element, a corresponding method, or a corresponding filter device that avoids the aforementioned disadvantages. In particular, the risk of contamination of a product filtered out of a medium stream using the ring filter element is to be reduced.

[0010] According to the invention, this problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0011] The invention is based on the general idea of arranging at least one holder, which has an adhesive body made of an adhesive, radially between the inner frame and the filter body. The respective holder surrounds the inner frame in a ring or spiral shape. During manufacture of the ring filter element, the adhesive of the adhesive body is initially not activated, which makes it easy to assemble the ring filter element by first attaching one or more holders to the outer side of the frame and then coaxially inserting the inner frame and the filter body into one another. The adhesive is then activated in a suitable manner so that it hardens and firmly bonds at least to the filter material. When the adhesive has hardened, the holder is held directly and / or indirectly radially on the inside of the inner frame and firmly connected to the filter body on the outside by means of the adhesive body.In this way, the filter body is fixed radially to the inner frame with the help of the holder, so that the filter body cannot lift off the inner frame even when flowing radially from the inside to the outside, i.e. in particular during backwashing. This reduces the mechanical stress on the filter material during such regeneration processes. During filtration, the respective holder, in particular its adhesive body, is located on the downstream side of the filter body, while the product to be separated from the medium accumulates on the upstream side of the filter body. This prevents contamination of the product accumulating on the filter body during filtration with particles from the holder, in particular the adhesive body.

[0012] The holder is held radially directly on the inner frame. This can be achieved simply by the annular or spiral holder encompassing the inner frame and thus being held radially on the inner frame in a form-fitting manner. According to the invention, the holder is attached to the inner frame so that it is neither radially nor axially movable relative to the inner frame. This is achieved according to the invention by the holder being bonded to the inner frame by the adhesive of the adhesive body. In particular, the holder can then be formed by the adhesive body or consist of it.

[0013] According to a particularly advantageous embodiment, the holder can have at least one annular or spiral reinforcement that surrounds the inner frame and is bonded directly to the adhesive body on the radial outside by the adhesive of the adhesive body. The reinforcement reinforces the holder and can absorb high forces. It can be made of plastic or metal. The reinforcement can be firmly bonded to the adhesive body on the radial outside by the adhesive. Likewise, the reinforcement can be embedded in the adhesive of the adhesive body, i.e., penetrated by the adhesive.

[0014] According to an advantageous development, the reinforcement can have a grid structure through which the adhesive of the adhesive body penetrates, so that the adhesive body is bonded radially inward directly to the inner frame by the adhesive of the adhesive body and through the reinforcement. Thus, the holder is bonded radially inward to the inner frame and radially outward to the filter body by the adhesive body, while it is reinforced in its interior, i.e., radially between the inner frame and the filter body, by the reinforcement.

[0015] A particularly advantageous embodiment is one in which the reinforcement is directly attached to the inner frame, independent of the adhesive. This can be achieved, for example, by at least one welded or soldered connection or by at least one other mechanical fastening element, such as a clip or clamp. This simplifies the assembly of the ring filter element, since the holder can be axially fixed to the inner frame by means of the reinforcement fixed to the inner frame before the adhesive is activated. For example, the filter body can be more easily pushed onto the inner frame with the holder as long as the adhesive is not activated.

[0016] In particular, the reinforcement can be formed with a metal mesh or metal mesh. This provides the reinforcement with high strength and can be easily attached to the inner frame, which is then preferably also made of metal, using one or more spot welds.

[0017] A preferred embodiment is one in which the respective adhesive body extends only over a portion of the axial length of the inner frame, with the reinforcement extending either over the entire axial length of the inner frame or only in the region of the respective adhesive body over a portion of the axial length of the inner frame. The reinforcement can be designed to be permeable to the medium to be filtered. The adhesive body, in contrast, is impermeable to the medium. Due to the small axial extent of the adhesive body, the filtration effect of the ring filter element is only slightly impaired by the attachment of the holder.

[0018] According to the invention, the inner frame has a support structure with radial openings through which the medium can flow. According to the invention, the adhesive penetrates at least partially into some of these openings and can in particular fill and / or penetrate them. This achieves particularly efficient adhesion through positive locking. Furthermore, it can be provided that the adhesive radially penetrates some of these openings and engages behind the support structure. In other words, the adhesive reaches a radially inner side of the frame and can there spread in the circumferential direction and in the axial direction beyond a boundary of the openings and thus engage behind the support structure in a form-fitting manner. The adhesive then also bears against the inside of the frame. As a result, the support structure is at least partially embedded in the adhesive. The holding force of the connection is therefore particularly high.Accordingly, the adhesive body or the adhesive can be attached to the filter body by means of a positive fit.

[0019] According to a further development, the adhesive can penetrate the filter material on the inside of the body, so that the filter material is embedded in the adhesive there. This results in a particularly strong bond that can transmit large forces. The adhesive preferably penetrates the filter material only to the extent that a gap remains between the adhesive and the outside of the filter. In particular, this prevents the adhesive from completely penetrating the filter material.

[0020] According to another embodiment, the ring filter element can have an end plate at each of its axial ends, which axially delimits the filter body and is attached to the inner frame and the filter body. The end plates can be made of plastic or metal. The inner frame can be made of plastic or metal. The end plates and the inner frame are expediently made of the same material. The filter material is expediently pleated. The filter material can be multi-layered.

[0021] Depending on the axial length of the ring filter element and the compressive load on the ring filter element, a single holder may be sufficient. Embodiments are also conceivable in which several such holders are provided, arranged axially spaced from each other and from the axial ends of the filter body and the inner frame.

[0022] A preferred embodiment is one in which each holder, or at least one of the holders, extends over at least 360° in the circumferential direction. This ensures that the inner side of the body is secured to the outer side of the frame in a closed manner in the circumferential direction.

[0023] The filter material can be advantageously pleated so that adjacent folds are each connected to one another by a fold. With a pleated filter material, the inner side of the body is formed by the radially inner folds. With a pleated filter material, it can advantageously be provided that each holder, or at least one of the holders, extends in the circumferential direction and is firmly connected to all radially inner folds. This measure also ensures that the inner side of the body is secured to the outer side of the frame in a closed manner in the circumferential direction.

[0024] A particularly advantageous embodiment is one in which each or at least one of the holders is ring-shaped, ring-segment-shaped, or helical or helical-segment-shaped and extends in the circumferential direction. In particular, the respective holder can thus also form a ring, which can, for example, be shaped as a circle if it lies in a radial plane perpendicular to the longitudinal center axis of the ring filter element, or as an ellipse if it lies in a plane inclined relative to the radial plane.

[0025] If the adhesive is configured to exhibit a certain degree of adhesion even before activation, another embodiment may provide for the holder to have, in addition to the adhesive body, a non-adhesive cover strip or a non-stick coating, in order to allow easy manual handling of the quasi-self-adhesive adhesive body and its installation on the inner frame before the adhesive is activated. Such a cover strip can be removed before the filter body is installed. Such a non-stick coating can be configured to be dissolved and / or destroyed by the activation of the adhesive.

[0026] A method according to the invention for producing such a ring filter element is characterized in that at least one holder is first fixed to the outer side of the frame, the adhesive not yet being activated. The adhesive penetrates at least partially into through-openings of a support structure of the inner frame. The filter body and the inner frame are then arranged against one another in such a way that the inner side of the body subsequently rests at least on the respective holder. For example, the filter body can be pushed onto the inner frame. It is also conceivable to push the inner frame into the filter body. Due to the elasticity of the filter body and appropriate dimensioning of the filter body and inner frame, the inner side of the body expediently rests against the outer side of the frame even outside the holder.

[0027] The adhesive of the respective holder is then activated, causing it to harden and bond firmly to the inner frame and the filter body. After hardening, the adhesive remains dimensionally stable. The cured adhesive can be rubber-elastic or comparatively rigid and stiff. Depending on the adhesive, activation can occur thermally or inductively, or with an auxiliary material.

[0028] It is advisable to press the filter material against the inner frame, at least while the adhesive is curing. This achieves the desired positioning between the filter body and the inner frame, in which the inner side of the body rests against the outer side of the frame, so that the filter material is directly supported by the inner frame. Furthermore, by pressing before and / or during curing, the filter material on the inner side of the body can penetrate into the adhesive body if, depending on the adhesive, the latter is flexible and displaceable like a viscous liquid before curing is complete. This allows the adhesive to penetrate, for example, into the reinforcement and / or the support structure of the inner frame or even penetrate it.

[0029] In a preferred embodiment, the adhesive can be a hot melt adhesive or a hot melt adhesive system, in particular a reactive hot melt adhesive, i.e., a hot melt adhesive based on polyurethane (PUR). These hot melt adhesive systems react, for example, with moisture in the material to be bonded or in the environment, such as the air. This not only results in a physical effect through the solidification of the (viscous) liquid adhesive, but also in a chemically reactive effect, which has a positive impact on the bonding properties in many ways. Reactive PUR hot melt adhesives are particularly advantageous with regard to adhesion properties or water and temperature resistance.

[0030] A filter device according to the invention for filtering a liquid or gaseous medium or for filtering out a product from a medium comprises at least one ring filter element of the type described above. Expediently, several such ring filter elements can be provided in the filter device, through which the respective medium flows, in particular in parallel. For this purpose, the filter device can have at least one holder for the respective ring filter element, which has a clean-side connection for discharging the filtered medium. The filter device is now designed to carry out a filtration operation in which the medium to be filtered flows through at least one such ring filter element radially from the outside to the inside. Furthermore, the filter device is designed to carry out a regeneration operation in which the medium to be filtered flows through at least one such ring filter element radially from the inside to the outside.During regeneration, the respective ring filter element is backwashed. This backwash can be conveniently performed with the cleaned medium. Backwashing is preferably performed under increased pressure, particularly in pulsed mode.

[0031] The filter device can be designed in particular to recover a product entrained in the medium to be filtered, e.g. in the food or pharmaceutical industries. The product is preferably formed by solid particles, while the medium is a gas, preferably air. It is also conceivable for the medium to be a liquid. Furthermore, the separation of a liquid product from a gaseous or even a liquid medium is also possible in principle. During filtration, this product collects on the upstream side of the respective ring filter element. The product can be removed from the respective ring filter element during regeneration. It then collects on the raw side of the filter device and can be easily removed from there.

[0032] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

[0033] It is understood that the features mentioned above and those to be explained below can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Components mentioned above and those to be mentioned below of a higher-level unit, such as a device, an apparatus, or an arrangement, which are designated separately, may form separate parts or components of this unit or be integral areas or sections of this unit, even if this is shown differently in the figures.

[0034] Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components.

[0035] They show, schematically, Fig. 1 a filter device with a ring filter element in longitudinal section during filtration operation, Fig. 2 the filter device with the ring filter element in longitudinal section during regeneration operation, Fig. 3 an enlarged detail III of the ring filter element from Fig. 1, Fig. 4 a longitudinal section of the ring filter element in three steps A, B and C during production.

[0036] According to the Fig. 1 and Fig. 2 comprises a filter device 1, which serves to filter a liquid or gaseous medium or to filter out a preferably solid product from the preferably gaseous medium, and at least one ring filter element 2 that is suitable for filtering the medium. In the example shown, only a single ring filter element 2 is shown, but it is clear that two or more ring filter elements 2 can also be arranged in the filter device 1, through which the medium can then expediently flow in parallel. The filter device 1 also comprises at least one holder 3 for receiving the respective ring filter element 2. The holder 3 has at least one connection 4, through which the respective medium can be discharged from the ring filter element 2 or fed to the ring filter element 2, depending on the operating state of the filter device 1.

[0037] The filter device 1 is designed to carry out a Fig. 1, which is defined by the fact that at least one ring filter element 2 is flowed through by the medium to be filtered radially from the outside to the inside. The flow through the ring filter element 2 during the filtration operation I is in Fig. 1 is indicated by arrows 5. The filtered medium is discharged via connection 4.

[0038] The filter device 1 is also designed to carry out a regeneration operation II, which is characterized in that at least one ring filter element 2 is flowed through radially from the inside to the outside. The flow through the ring filter element 2 during the regeneration operation II is in Fig. 2 indicated by arrows 6. A backwash medium, preferably a purified medium, is supplied via connection 4.

[0039] During filtration operation I, impurities, which can also be referred to as product and which are carried in the medium, are separated on the ring filter element 2, accumulating on an inflow side 7 of the ring filter element 2. During regeneration operation II, backwashing takes place, preferably with purified medium and expediently at increased pressure, whereby the inflow side 7 of the ring filter element 2 is freed from the impurities or product.

[0040] The ring filter element 2 is cylindrical or cylinder-shaped and therefore has a longitudinal central axis 8. This longitudinal central axis 8 defines an axial direction X indicated in the figures by a double arrow. The axial direction X runs parallel to the longitudinal central axis 8. The radial direction runs perpendicular to the axial direction X. The circumferential direction runs around the longitudinal central axis 8.

[0041] The ring filter element 2 has an annular filter body 9 made of a filter material 10. The medium can flow through the filter body 9. The filter material 10 can expediently be folded. In particular, the filter body 9 can form a so-called pleated star. Furthermore, the ring filter element 2 has an annular inner frame 11 made of a support material. The inner frame 11 is arranged concentrically in the filter body 9 and can also be flowed through by the medium. For this purpose, the inner frame 11 can have a support structure 12 having a plurality of radial openings 13, whereby the support structure 12 or the inner frame 11 can be flowed through by the medium. The support material of the inner frame 11 itself, however, is impermeable to the medium. The flow through the inner frame 11 therefore occurs exclusively through the openings 13.

[0042] The filter body 9 has a radially inner body side 14 and a radially outer body side 15. In a pleated filter material 10, the body inside 14 is formed by the radially inner folds, while the body outside 15 is formed by the radially outer folds. In a pleated filter material 10, adjacent folds are each connected to one another by an inner or outer fold. The inflow side 7 of the filter body 9 is formed by the outer surface of the filter material 10. An outflow side 16 of the filter body 9 is formed by the inner surface of the filter material 10. The inflow side 7 and the outflow side 16 refer to the filtration operation I and the associated flow direction from radially outside to inside and, in a pleated filter material 10, include the surfaces of the folds.

[0043] The inner frame 11 has a radially outer frame outer side 17 and a radially inner frame inner side 18. In the ring filter element 2 presented here, the filter body 9 rests radially with its body inner side 14 against the frame outer side 17. This radial contact can occur essentially over the entire axial extent of the filter body 9 and the inner frame 11. This contact enables direct radial support. In the area of the holders 19 explained in more detail below, however, the radial support can occur indirectly, namely via the respective holder 19. In the area of the respective holder 19, the filter body 9 rests against the holder 19 and possibly not against the inner frame 11. For filtration operation I, the filter body 9 can thus support the pressure difference between the inflow side 7 and the outflow side 16 on the inner frame 11, thereby relieving the filter material 10.

[0044] The ring filter element 2 presented here is also equipped with at least one holder 19, which is arranged axially between the axial ends of the filter body 9 and the inner frame 11. In the example shown, the ring filter element 2 has an end plate at each of the axial ends of the filter body 9 and the inner frame 11, namely a first end plate 20 and a second end plate 21. The first end plate 20 faces the connection 4 of the holder 3 and can be designed as an open end plate. The second end plate 21, on the other hand, is located at the axial end facing away from the connection 4 and can be designed as a closed end plate. In the example shown, the ring filter element 2 is equipped with only a single holder 19.

[0045] It is clear that two or more such holders 19 can also be provided, which are then arranged axially spaced from one another.

[0046] Fig. 3 shows an enlarged section of the cut ring filter element 2 in the area of such a holder 19. According to the Fig. 1 to 3, the respective holder 19 has an adhesive body 22 consisting of a cured adhesive. This adhesive body 22 is firmly connected radially outwardly to the filter body 9. In principle, the adhesive of the adhesive body 22 can be Fig. 3 penetrate into some of the through-openings 13 of the inner frame 11, creating a positive connection between the adhesive body 22 and the inner frame 11. It is also conceivable for the adhesive to penetrate some of the through-openings 13, preferably in such a way that the adhesive thereby engages behind the support structure 12. In detail, the adhesive then penetrates the respective through-opening 13 radially and extends on the inner side 18 of the frame in the axial direction and in the circumferential direction beyond an opening edge of the respective through-opening 13. In other words, the adhesive body 22 then also rests against the inner side 18 of the frame and is supported thereon. This results in a particularly intensive positive connection between the adhesive body 22 and the inner frame 11.

[0047] Furthermore, it is expediently provided that the adhesive penetrates into the filter material 10 on the inner side 14 of the body, so that the filter material 10 is embedded in the adhesive there. For example, the filter material 10 has a fiber structure that forms pores. The adhesive penetrates these pores and engages behind the fiber structure, so that a positive connection is formed there as well. In particular, the adhesive encompasses a plurality of fibers of the filter material 10, whereby the filter material 10 is embedded in the adhesive. Accordingly, a firm and stable connection is also produced here between the adhesive body 22 and the filter body 9.

[0048] The holder 19 thus ensures a firm connection of the body inner side 14 to the frame outer side 17 and thus a firm connection between the filter body 9 and the inner frame 11. In the example shown, the holder 19 extends in the circumferential direction over at least 360° and thus ensures a connection between the inner frame 11 and the filter body 9 that runs completely around the circumferential direction. In the folded filter material 10, the holder 19 extends in the circumferential direction and is firmly connected to all radially inner folds.

[0049] The embodiment shown here is particularly advantageous, in which the holder 19 is annular and extends in the circumferential direction. In particular, the holder 19 can form a closed ring, as shown. In the example, the annular holder 19 is shaped like a circle and lies in a radial plane perpendicular to the longitudinal center axis 8 of the ring filter element 2.

[0050] According to the Fig. 1 to 3, the holder 19 can have at least one annular or spiral reinforcement 25 enclosing the inner frame 11. The reinforcement 25 is bonded radially outwardly directly to the adhesive body 22 by the adhesive of the adhesive body 22. The reinforcement 25 reinforces the holder 19 and can absorb high forces. It can be made of plastic or metal. It can be annular and completely circumferential. It can be designed as a closed ring. The reinforcement 25 preferably has a lattice structure so that it is permeable to the adhesive as long as the adhesive is not cured and flowable. The reinforcement 25 can thus be embedded in the adhesive of the adhesive body 22, i.e., penetrated by the adhesive. According to Fig. 3, the adhesive of the adhesive body 22 can penetrate radially inward through the reinforcement 25 to the inner frame 11 and be bonded there directly to the inner frame 11. Thus, the holder 19 is bonded radially inward to the inner frame 11v and radially outward to the filter body 9 by the adhesive body 22, while it is reinforced in its interior, i.e. radially between the inner frame 11 and the filter body 9, by the reinforcement 25.

[0051] A particularly advantageous embodiment is one in which the reinforcement 25 is directly attached to the inner frame 11, independent of the adhesive. This can be achieved, for example, by at least one welded connection 26, which Fig. 3 is indicated. In this case, the inner frame 9 and the holder 19 are made of similar or identical materials, e.g. plastic or metal. Alternatively, a soldered connection or a connection with at least one mechanical fastening element is also conceivable, such as a clip or a clamp. This simplifies the assembly of the ring filter element 2, since the holder 19 can be axially fixed to the inner frame 11 by means of the reinforcement 25 fixed to the inner frame 11 before the adhesive is activated and / or cured. For example, the filter body 9 can be pushed more easily onto the inner frame 11 with the holder 19 as long as the adhesive is not activated.

[0052] An embodiment is preferred in which the respective adhesive body 22 extends only over a portion of the axial length of the inner frame 11. The reinforcement 25 can, in principle, extend over the entire axial length of the inner frame 11. However, as in the examples shown, the reinforcement 25 preferably extends only in the region of the respective adhesive body 22, i.e., over a portion of the axial length of the inner frame 11.

[0053] The ring filter element 2 presented here is thus characterized by at least one internal holder 19, where the term "internal" refers to the arrangement of the holder 19 on the downstream side 16 of the filter body 9 during filtration operation I. This prevents the holder 19 from coming into contact with the contaminants or product entrained in the medium. The internal holder 19 is arranged quasi-radially between the filter body 9 and the inner frame 11.

[0054] The following is based on the Fig. 4A, Fig. 4B and Fig. 4C a method for producing such a ring filter element 2 is presented.

[0055] First, in step A according to Fig. 4A, the at least one holder 19 is fixed to the outer side 17 of the frame. In this case, the adhesive of the adhesive body 22 is not yet activated and is therefore in an initial state or raw state. In this initial state, the adhesive can be liquid, preferably viscous. The respective holder 19 can be provided, for example, as an endless strip material. The holder 19 can be designed to be self-adhesive, so that it adheres automatically to the outer side 17 of the frame. For example, the holder 19 can be designed to be adhesive or sticky at least on its radial inner side 23 facing the inner frame 11. To simplify handling and assembly of the holder 19, a radial outer side 24 of the holder 19 facing away from the inner frame 11 can, on the other hand, be designed to be non-adhesive or non-adhesive. In the initial state, the adhesive preferably has an adhesive surface which is used to adhere the holder 19 to the inner frame 12 oron the reinforcement 25. The radial outer side 24 of the holder 19 can expediently be deactivated with respect to the adhesive effect. For example, the surface of the adhesive on the outer side 24 can be provided or sealed with a non-adherent coating, i.e., with a non-stick coating. For example, the non-stick coating can be configured as a wax coating, which can have a small layer thickness, in particular less than 10 µm.

[0056] If, as here, the reinforcement 25 is used, the holder 19 can be prefabricated with this reinforcement 25. The holder 19 can then be fixed in the desired position by securing the reinforcement 25 to the inner frame 11. It is clear that the welded joint 26 then lies outside the adhesive body 22. Alternatively, the holder 19 can also be assembled on the inner frame 11 by first attaching and securing the reinforcement 25 to the inner frame 11 and then arranging the adhesive body 22 on the reinforcement 25.

[0057] In a step B, according to Fig. 4B, the filter body 9 and the inner frame 11 are inserted into one another in such a way that the inner side 14 of the body rests at least on the respective holder 19. Since the filter material 10 usually has a certain elasticity, the dimensions of the inner frame 11 and the filter body 9 can be coordinated such that the filter body 9 rests on the inner side 14 of the body against the inner frame 11 or the respective holder 19 essentially over the entire axial length. It is clear that gaps can arise at the transition between the inner frame 11 and the respective holder 19, in which gaps the inner side 14 of the body rests neither on the inner frame 11 nor on the respective holder 19. The filter body 9 and the inner frame 11 can be inserted together in such a way that the filter body 9 is pushed onto the inner frame 11. Likewise, the inner frame 11 can be pushed into the filter body 9.

[0058] In a step C, according to Fig. 4C an activation of the adhesive so that it hardens and subsequently bonds firmly with the filter body 9. For an optimal bond of the adhesive with the filter body 9 and, if applicable, with the reinforcement 25 and, in particular, also with the inner frame 11, the filter body 9 can be pressed radially against the inner frame 11 and, if applicable, against the reinforcement 25 before and during the curing process of the adhesive. This pressure application is in Fig. 4C by arrows 27. Before curing, the adhesive is virtually flowable and displaceable, so that in a folded filter material 10, the inner folds can be pressed into the adhesive. As already explained above, the adhesive can also penetrate into any reinforcement 25 present before curing. It is also conceivable that the adhesive penetrates the reinforcement 25 and gnaws down to the inner frame 11. The adhesive can also penetrate some of the through-openings 13 and, in extreme cases, even penetrate them and spread further along the inner side 18 of the frame, in particular also in the circumferential direction and in the axial direction X. In addition, the adhesive can penetrate into the filter material 10, whereby the filter material 10 is ultimately embedded in the adhesive.

[0059] The activation of the adhesive can be carried out in any suitable manner, but may depend on the adhesive used. An embodiment in which a water-activated adhesive is used is preferred. For this purpose, the assembly, which comprises at least the inner frame 11, the respective holder 19, and the filter body 9, can be subjected to steam, for example. This steam application is described in Fig. 4C indicated by arrows 28.

Claims

[1] Ring filter element (2) for filtering a liquid or gaseous medium, - with an annular filter body (9) made of a filter material (10) through which the medium can flow, and - with an annular inner frame (11) made of a supporting material, which is arranged concentrically in the filter body (9) and through which the medium can flow, - wherein the filter body (9) is supported directly or indirectly with its radially inner body inner side (14) on a radially outer, cylindrical frame outer side (17) when it is pressed against the inner frame (11) during a flow from radially outside to inside, - wherein the inner frame (11) has a support structure (12) with radial passage openings (13) through which the medium can flow, - wherein the ring filter element (2) has at least one ring-shaped or spiral-shaped holder (19) which surrounds the inner frame (11) and is arranged on the inside of the body (14), - wherein the holder (19) has an annular or spiral adhesive body (22) made of an adhesive, - wherein the adhesive body (22) is bonded radially outwardly directly to the filter body (9) by the adhesive of the adhesive body (22), characterized by , - that the adhesive penetrates at least partially into some of the through-openings (13) of the support structure (12), so that the holder (19) is fixed radially inwardly to the inner frame (11). [2] Ring filter element (2) according to claim 1, characterized by that the holder (19) has at least one annular or spiral reinforcement (25) which surrounds the inner frame (11) and is bonded directly to the adhesive body (22) by the adhesive of the adhesive body (22). [3] Ring filter element (2) according to claim 2, characterized by that the reinforcement (25) has a lattice structure which is penetrated by the adhesive of the adhesive body (22), so that the adhesive body (22) is bonded radially inwardly by the adhesive of the adhesive body (22) through the reinforcement (25) directly to the inner frame (11). [4] Ring filter element (2) according to claim 2 or 3, characterized by that the reinforcement (25) is directly attached to the inner frame (11) independently of the adhesive. [5] Ring filter element (2) according to one of claims 2 to 4, characterized by that the reinforcement (25) is formed with a metal grid. [6] Ring filter element (2) according to one of claims 2 to 5, characterized by , - that the respective adhesive body (22) extends only over part of the axial length of the inner frame (11), - that the reinforcement (25) extends either over the entire axial length of the inner frame (11) or only in the area of the respective adhesive body (22) over part of the axial length of the inner frame (11). [7] Ring filter element (2) according to one of the preceding claims, characterized by that each holder (19) or at least one such holder (19) extends in the circumferential direction over at least 360°. [8] Ring filter element (2) according to one of the preceding claims, characterized by that the respective holder (19) extends only over part of the axial length of the inner frame (11). [9] Ring filter element (2) according to one of the preceding claims, characterized by , - that the filter material (10) is folded, with adjacent folds each being connected to one another by a fold, - that each holder (19) or at least one such holder (19) extends annularly or spirally in the circumferential direction and is firmly connected to all radially inner folds. [10] Method for producing a ring filter element (2) according to one of the preceding claims, comprising the following steps: A: Fixing at least one holder (19) to the outer side (17) of the frame, wherein the adhesive has not yet cured, wherein the adhesive of the adhesive body (22) penetrates at least partially into some of the passage openings (13) of the support structure (12), B: Arranging the filter body (9) and the inner frame (11) against each other so that the inner side of the body (14) rests at least on the respective holder (19), C: Activate the adhesive so that it hardens and bonds firmly to the filter body (9). [11] Method according to claim 10, characterized bythat in order to fix the respective holder (19) in step A the reinforcement (25) is attached to the inner frame (11). [12] Method according to claim 10 or 11, characterized by that during step B and / or during step C the filter material (10) is pressed radially against the inner frame (11). [13] Method according to one of claims 10 to 12, characterized by that during step B and / or during step C the filter material (10) is pressed radially against the inner frame (11) in such a way that the adhesive of the adhesive body (22) penetrates into the filter material (10) and / or penetrates into the grid structure of the reinforcement (25) and / or penetrates the grid structure of the reinforcement (25) and comes into contact with the inner frame (11). [14] Method according to one of claims 10 to 13, characterized by that the activation in step C is carried out by applying steam to the holder (19). [15] Method according to one of claims 10 to 14, characterized by that the adhesive is viscous, at least in step B. [16] Filter device (1) for filtering a liquid or gaseous medium, - with at least one ring filter element (2) according to one of claims 1 to 9, - wherein the filter device (1) is designed to carry out a filtration operation (I), in which at least one ring filter element (2) is flowed through radially from the outside to the inside by the medium to be filtered, - wherein the filter device (1) is designed to carry out a regeneration operation (II), in which at least one ring filter element (2) is flowed through radially from the inside to the outside.

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