METHOD FOR PRODUCING A FILTER ELEMENT PROVIDED WITH A SEALING PART

Description

Technical field

[0001] The invention relates to a method for producing a filter element provided with a sealing part. State of the art

[0002] WO 2009 / 150165 A1 describes a filter device for filtering gaseous fluids. The filter device comprises a filter insert with a filter medium and a sealing element clamped between sealing webs on housing parts of the filter housing. The filter element is rectangular in shape and consists of a folded filter paper, which is enclosed by the sealing element around its edge. In the installed position, a sealing section of the sealing element protrudes into a receiving channel formed on one of the housing parts. A second housing part covers the sealing element and presses the sealing section transversely to the mounting direction of the filter insert. Further sealing variants for filter devices are known from US 5 529 476 A, US 2009 / 255227 A1, EP 2 140 922 A2, WO 2006 / 017790 A1 and DE 2 301 635 A1.

[0003] The sealing element surrounding the filter element is usually injection-molded or foamed onto the filter element. For this purpose, molding shells are provided into which the uncured sealing material is introduced, after which the sealing element is inserted. After curing, the sealing material is firmly bonded to the edge area of ​​the filter element. Ventilation openings are provided in the molding shell, into which the uncured sealing material is introduced, through which the sealing material can escape. After curing, drop-shaped elevations of sealing material are located on the outside of the sealing element in the area of ​​the ventilation openings. These elevations must be trimmed off to create a smooth sealing surface on the sealing element. Disclosure of the invention

[0004] The invention is based on the object of producing a filter insert part comprising a filter element and a sealing part using simple measures.

[0005] This object is achieved according to the invention with the features of claim 1. The subclaims specify expedient further developments.

[0006] The method according to the invention relates to the production of a filter insert for a filter device, which is preferably used for gas filtration, for example, for filtering the intake air for an internal combustion engine. However, within the scope of the disclosure, the use of the filter insert in a filter device for liquid filtration, for example, as a fuel or oil filter, is also generally contemplated.

[0007] The filter insert comprises a filter element and a sealing part arranged on the filter element, preferably a circumferential sealing part. The filter insert is inserted into a filter housing of the filter device, wherein the sealing part separates the raw side from the clean side of the filter element and, when installed, lies sealingly against a wall of the filter housing. For example, it is possible for a sealing section of the sealing part to be accommodated in a receiving channel of the housing and to be subjected to a force by another housing part, such as a cover. The direction of application is either parallel to the flow direction through the filter element, i.e. axial, or transverse to the flow direction, i.e. radial.

[0008] The filter element is, for example, a cuboid-shaped filter element surrounded by the sealing part. The filter element can optionally consist of a zigzag-folded filter paper.

[0009] To produce the sealing part on the filter element of the filter insert part, at least two casting shell parts are used, which are designed such that a casting chamber is formed between the casting shell parts, which serves to accommodate the sealing material in the uncured state. In particular, the at least two casting shell parts are put together to form the chamber. The casting chamber is filled with the sealing material and can then cure, whereby the sealing part is obtained. The casting chamber is designed, for example, such that a first chamber wall of the casting chamber is formed by the first casting shell part and a second chamber wall of the casting chamber is formed by the second casting shell part, wherein the sealing part in the cured, set state has sealing surfaces which each correspond to at least a section of the chamber walls of different casting shell parts.Thus, at least one sealing surface is created on the sealing part via each casting shell part.

[0010] Furthermore, a compensation chamber is provided in the casting chamber for the expansion of the sealing material during the curing process. In addition to or as an alternative to the compensation chamber within the casting chamber, a design is also conceivable in which the compensation chamber is arranged outside the casting chamber and connected to the casting chamber, so that in this design too, sealing material can flow into the compensation chamber during the curing process. The end face of the sealing part that expands into the compensation chamber does not necessarily form a sealing surface, so that the exact geometry of this end face of the sealing part does not play a decisive role in the seal between the raw and clean sides. This provides an additional degree of freedom in the manufacturing process, as the amount of sealing material used in the uncured state only has to lie within a defined range.If this range is maintained, the compensation space provides a sufficiently large compensation volume into which excess sealing material can expand without affecting the remaining geometry of the sealing component, particularly the sealing surfaces. Additional venting openings, which are provided in the prior art, can be eliminated, so that after the sealing material has cured, the sealing surfaces are smooth-walled and without protruding sealing lugs, and no or only minimal post-processing is required.

[0011] In principle, it is possible for the end face of the sealing part protruding into the compensation chamber to be adjacent to a sealing surface and to form an angle with the sealing surface. Designs in which the end face is spaced from the sealing surfaces of the sealing part are also possible. If the end face does not have a sealing function, the extent to which the end face protrudes into the compensation chamber plays only a minor role, which allows for the dosage of the sealing material within wider limits.

[0012] A suitable sealing material is PUR (polyurethane) foam. In principle, any sealing material that is liquid or foam-like in its uncured state and can be poured into the casting chamber between the two casting shell parts can be used.

[0013] The filter element, to whose edge area the sealing part is attached, is inserted into the casting shell parts during the production of the sealing part, so that contact with the edge area of ​​the filter element is already established in the uncured state of the sealing material. After curing, the sealing part is firmly connected to the filter element.

[0014] In an embodiment according to the invention, the compensation space can be formed as a closed space within a casting shell part or, in the assembled state, by both casting shell parts, which is part of the casting chamber or communicates with the casting chamber. During the manufacturing process, the amount of uncured sealing material introduced into the casting chamber is dimensioned such that, in the cured state, the end face protruding into the compensation space is at a distance from the floor or ceiling of the compensation space. This distance represents a safety margin so that fluctuations in the filling quantity of the sealing material or in the expansion behavior of the curing sealing material can be compensated. In particular, subsequent trimming of the sealing part can be eliminated.

[0015] According to a further embodiment of the invention, the compensation chamber is designed as a space that is open to the outside but communicates with the casting chamber, allowing sealing material to flow from the casting chamber into the compensation chamber and spread there. In this embodiment, too, it is sufficient to fill only an approximately determined amount of sealing material, since fluctuations can be absorbed via the open compensation chamber. According to the invention, the open compensation chamber is delimited by both casting shell parts, which simplifies demolding after completion of the casting process.

[0016] According to the invention, the compensation space and the section of the sealing part projecting into the compensation space are spaced apart from the facing side surface of the filter element.

[0017] Furthermore, it may be advantageous to provide the sealing part with a chamfer on at least one side, which is either introduced after curing, for example, by trimming the sealing part, or created during the casting process by appropriately shaping the casting shell parts. The chamfer(s) facilitates the assembly of the filter insert part in the filter housing. Short description of the drawings

[0018] Further advantages and practical embodiments can be found in the further claims, the description of the figures, and the drawings. They show: Fig. 1 a perspective view of two casting shell parts that define a casting chamber for producing a sealing part on a filter element, Fig. 2 a section through a filter device with a filter insert, which has a filter element and a sealing part cast onto the edge area of ​​the filter element, Fig. 3in one embodiment, two casting shell parts for producing a sealing part on a filter element, Fig. 4 the filter element according to Fig. 3 when installed, Fig. 5 a sealing element in isolation, Fig. 6 another sealing element.

[0019] In the figures, identical components are provided with the same reference symbols. Embodiment(s) of the invention

[0020] In Fig. 11 shows a casting device 1 with a first casting shell part 2 and a second casting shell part 3, which serves to produce a filter insert part 4 comprising a filter element 5 and a sealing part 6. By means of the casting device 1 with the casting shell parts 2, 3, the sealing part 6 can be produced and connected to the edge region of the filter element 5 by casting or injection molding. The filter element 5 is, for example, an air filter element which consists, for example, of a folded filter paper and is rectangular in shape, wherein the edge region of the filter element 5 is provided with the circumferential sealing part 6 on two sides of the filter element.

[0021] The two casting shell parts 2, 3 define a casting chamber 7 into which the sealing material is poured in its uncured state. This is advantageously done by first joining the two casting shell parts 2, 3, then moving the filter element 5 into the intended position, and finally filling the sealing material in its uncured state into the casting chamber 7. However, it is also possible to first fill the sealing material into the casting chamber and then move the filter element into its intended position, in which the edge area protrudes into the sealing material. After the sealing material has hardened, the casting shell parts 2, 3 can be removed; the sealing part 6 retains its shape and is firmly connected to the edge area of ​​the filter element 5.

[0022] A compensation chamber 8 is incorporated into the casting shell part 2, which is connected to the casting chamber 7 and is designed as a closed space with a U-shaped cross-section. As the sealing material is filled, it extends into the compensation chamber 8. The amount of sealing material filled is dimensioned such that, even after curing, the end face 9 of the sealing material protruding into the compensation chamber 8 remains at a distance from the floor or ceiling 10 of the U-shaped, closed compensation chamber 8. This distance represents a compensation reserve and makes it possible to compensate for fluctuations in the dimensioning of the sealing material quantity or in other process parameters that determine the volume in the cured state.

[0023] The two lateral sealing surfaces 11 and 12 of the section of the sealing part 6 projecting into the compensation chamber 8 are delimited by the opposite chamber walls of the compensation chamber 8. The sealing surfaces 11 and 12 can be subjected to a sealing force when the filter insert part is installed.

[0024] The compensation chamber 8 and the section of the sealing part 6 projecting into the compensation chamber 8 are spaced apart from the facing side surface of the filter element 5. A further section of the sealing part 6 extends between the outer side of the first casting shell part 2 and the side surface of the filter element 5 and encloses the edge region of the filter element 5.

[0025] The second casting shell 3 defines a further sealing surface 13 on a section of the sealing part 6. This further sealing surface 13 is spaced apart from the first two sealing surfaces 11 and 12, which are parallel to each other and correspond to the chamber walls of the compensation chamber 8. In Fig. 2 a filter device 14 is shown, which has a filter insert part 4, which according to the embodiment according to Fig. 1is manufactured. The filter device 14 has a filter housing 15 into which the filter insert part 4 can be inserted, wherein the sealing part 6 rests on the edge region on the front side of the filter housing 15 and is acted upon by a cover 16 which can be fastened to the filter housing 15 by means of a connecting element (not shown), such as a screw. The direction in which the sealing force is applied for sealing by means of the sealing surfaces 11 and 12 runs transversely to the direction of flow through the filter element 5. This is therefore at least essentially a radial seal. An additional (smaller) component of the sealing force is introduced via the sealing surface 13 parallel to the direction of flow through the filter element 5.

[0026] In the Figs. 3 and 4 another embodiment is shown. Fig. 3shows a casting device 1 with two casting shell parts 2 and 3, between which a casting chamber 7 is formed for producing a sealing part 6 on a filter element 5, wherein the filter element 5 and the sealing part 6 together form a filter insert part 4. The two casting shell parts 2 and 3 of the casting device 1 delimit a casting chamber 7 for receiving the sealing material. In addition, an open compensation space 8 is provided between the two casting shell parts 2 and 3, which is open to the outside, i.e. to the environment. As the sealing material is poured into the casting chamber 7, the sealing material also spreads into the compensation space 8, which is connected to the casting chamber 7. After curing, an end face 9 is formed on the open end of the section of the sealing part 6 protruding into the compensation space, which, however, does not perform a sealing function when the filter insert part is installed.The chamber walls of the casting chamber 7, which are each formed by side walls of the casting shell parts 2 and 3, define the sealing surfaces 11 and 12 of the section of the sealing part 6 formed in the casting chamber 7.

[0027] In Fig. 4 The filter device 14 is shown with the installed filter insert part 4. The sealing part 6 is delimited by the mutually facing end faces of the filter housing 15 and the cover 16 and is subjected to a sealing force. The direction of application of the sealing force for sealing by means of the sealing surfaces 11 and 12 runs parallel to the flow direction of the filter element 5. This is therefore at least essentially an axial seal. The free end face 9 protrudes into a receiving channel, but does not perform a sealing function.

[0028] Like the Figs. 5 and 6As can be seen, various sides of the sealing part 6 can be provided with a chamfer 18 or 19. This particularly facilitates insertion into the filter housing. One or more such chamfers 18, 19 can be provided, the angle of which is adapted to the respective installation situation. The chamfers 18, 19 are either already produced during the casting process by providing corresponding chamfers in the casting shell parts. The chamfers on the sealing part 6 can also be created subsequently by mechanical machining.

[0029] For tree shapes according to the Figs. 5 and 6 The sealing surfaces 11 and 12 run essentially parallel to the flow direction of the filter element 5. The direction of application of the sealing force therefore runs perpendicular to the flow direction. In these cases, these seals are radial.

Claims

1. Method for manufacturing a filter element (5) provided with a sealing element (6), in which the sealing compound is introduced in the uncured state into a casting chamber (7) between at least two tundish parts (2, 3), wherein the casting chamber (7) is designed such that sealing surfaces (11, 12, 13) are formed on the sealing element (6) on opposite chamber walls, and that in the casting chamber (7) or connected to the casting chamber (7), a compensation space (8) is provided for spreading the sealing material, characterized in that the filter element (5) is placed on the tundish parts (2, 3) and the sealing material is cast, injection-molded or foamed directly on the peripheral area of the filter element (5), and that the end face (9) of the sealing element (6) projecting into the compensation space (8) differs from the sealing surfaces (11, 12, 13), wherein the compensation space (8) and the section of the sealing element (6) projecting into the compensation space (8) are at a distance from the side face of the filter element (5) facing it, wherein either the compensation space (8) is disposed as a closed space within a tundish part (2, 3) and the quantity of uncured sealing compound introduced into the casting chamber (7) is dimensioned such that, in the cured state, the end face (9) of the sealing element (6) lies at a distance from the ceiling (10) of the closed compensation space (8), or the compensation space (8) is bounded by both tundish parts (2, 3) and is designed as open space towards the top which communicates with the casting chamber (7).

2. Method according to claim 1, characterized in that a PUR foam (polyurethane) is used as sealing compound.

3. Method according to claim 1 or 2, characterized in that the end face (9) of the sealing element (6) adjoins at least one sealing surface (11, 12, 13) on the sealing element (6).

4. Method according to one of the preceding claims, characterized in that after curing at least one side of the sealing element (6) will be provided with a chamfer (18, 19).