MXPA99008714A - Air filter - Google Patents

Abstract

The invention relates to an air filter, specially for cleaning combustion air in internal combustion engines. The inventive filter comprises a metal-free filter insert (21) which is produced from a zig-zag folded filter medium (33). The filter medium forms a hollow cylinder wherein end plates (33, 34) are arranged on the front faces of the filter medium (33). Said end plates are made of thermoplastic elastomer or thermoplastic polyurethane.

Description

Air filter The present invention relates to a filter particularly for purifying the combustion air of internal combustion engines. From US-A-47 20 292 an air filter with the following characteristics is known: A housing with an axial outlet opening and a second substantially open end, which can be closed by means of a removable cover. An air inlet opening is provided by the casing sleeve. Inside the housing there is a substantially cylindrical filter element with an inner support tube, a filter with an external support tube, the inner filter element being arranged in the housing in coaxial form. The sealing of the filter element against the housing takes place through an end disk in the form of a washer, which has a substantially cylindrical wall, directed radially inward, which is inserted on an inner section of the outlet part. As is known per se, the filter cartridges of air filters are replaced after a certain time of service. Depending on the amount of dust suspended in the air, the service time of an air filter can be imported for a few days (for example in the case of construction machines) up to several months. The filter cartridge known from the above mentioned US patent, as well as other filter cartridges usually employed, are constituted by a combination of materials, being used particularly for steel sheet support tubes. The filter medium consists of paper or a nonwoven fabric made of plastic filaments, while the end discs consist of plastic (soft elastomer). The elimination of such air filters or their dismantling in their different component parts is linked to a high input and was therefore uneconomical as a result. Do not generate waste has in principle priority with respect to recycling and the elimination of garbage. The presupposition for a recycling process is that the recycling is technically possible, the costs of recycling admissible and that there is a market for the materials recovered or the energy generated, or that the market can be created. Only when these criteria can not be met, should the waste be properly disposed of. In the case of air filter cartridges, recycling was not possible due to the aforementioned disadvantages. Another disadvantage of the known state of the art lies in the fact that a relatively large housing is required for the air filter cartridge, which occupies an unnecessarily large space in the area of pure air. The present invention therefore has the purpose of providing a filter that can be made without metal, which can be eliminated without problems and which is constituted in the most compact form possible. The present invention therefore has the purpose of providing a filter with a metal-free construction, which can be discarded without problems and is built as compact as possible. Said purpose is satisfied with the independent claims. The fundamental idea of the present invention lies in the application of a material that is suitably suitable for the end washers in an air filter and in principle for the combination of a filter medium with support structures. Such a material is by way of example a thermoplastic elastomer, or a thermoplastic polyurethane. Thermoplastic elastomers are materials in which elastomeric phases are incorporated as soft components in plastics as hard components. Thermoplastic elastomers (abbreviated TPE) are not chemically irreversible like elastomers, but are physically crosslinked reversibly. Reversible crosslinking occurs because of its dual phase structure. With an adequate molecular architecture, the domains of the hard sequences form the physical points of crosslinking in a continuous matrix of the soft sequences, which are selected so that at the service temperature they are above their glass transition temperature (setting temperature). The vitreous transition temperature (if it is amorphous) or the melting temperature (if partially crystalline) of the hard sequences must be found on the contrary above the service temperatures for the domains of the substances can act as cross-linking points. The thermoplastic elastomers thus behave at operating temperatures as elastomers, however, above the characteristic transformation temperature, the hard sequences become mobile and the thermoplastic elastomers can be processed as thermoplastics. The great advantage of thermoplastic elastomers with respect to vulcanized elastomers lies in their substantially simpler processing, not being necessary chewing (oxidative decomposition), the mixture of vulcanization accelerators and in some cases also the combination and of course the vulcanization. Thermoplastic polyurethanes are, like all plastics in this family, polyisocyanate polyols and polyols. The rubber-like behavior results from the structure in the form of segments of the macromolecules. In this case, a hard segment with a soft segment is also combined. The thermoplastic polyurethanes are characterized by their high flexibility, also at low temperatures, high continuous service temperature, high tear resistance, high damping capacity, high resistance against grease, oils, solvents, as well as high energy and light radiations ultraviolet Thermoplastic polyurethane elastomers of polar structure can be mixed with other thermoplastics and processed together. A development of the present invention provides that the filter medium is additionally provided with support bodies, which can surround the filter medium and thereby increase its stability. Another embodiment of the present invention envisages providing at least one end disk with a sealing system, said end disk being able to have both an axially and radially oriented sealing structure. The end disk is preferably provided with a concentric collar, which bears a radial seal. Basically it is also possible to provide the elements consisting of thermoplastic elastomer and thermoplastic polyurethane with functional structures. By way of example, an end disk can also be provided with support bodies or with connecting elements. In an inventive process for the manufacture of the air filter, a hollow cylindrical element is first produced from a zig-zag folded filter medium. The end plates are applied by casting to the axial end faces of the folded filter element, for example by means of welding by means of high-temperature heating elements, these being connected to the filter medium. Instead of welding by means of high-temperature heating elements, butt welding with reflectors can also be used. These and other advantageous features of preferred embodiments of the invention are derived, in addition to the claims, also from the description and the drawings, each of the features being realizable by itself or in combination with others, in the object field. of the invention and other fields, and presents a susceptible version of protection that is requested with the present application. The present invention will be described in more detail below in connection with an example of embodiment, illustrating: Figure 1, a filter in sectional view. Figure 2, a filter element in a detailed view.

The filter strated in Figure 1 is represented in two halves of axial sections. The left half of the axial section strates the filter with the lid stslightly open, while the right half of the axial section strates the filter with the lid closed. The filter is constituted by a cylindrical housing 10 with an impure air inlet 11, and a pure air outlet 12. In the region of the impure air inlet, a baffle wall 13 (siphon tube) is provided. With the disposition of the impure air inlet that opens tangentially in the casing 10, a circulating flow of the impure air is generated, which causes a separation of the coarse dust particles, said coarse dust particles moving along the inner wall of the powder. filter down and being discharged outwards through a dust discharge opening 14 sealed by means of a dust discharge valve known per se. An advantageous embodiment of a filter is given by the fact that the central tube is arranged integrally with the housing. Since this central tube is not subject to abrasion or wear, its replacement is not necessary. Said central tube, which is constituted particularly of plastic, is advantageously connected by positive connection with the socket of the housing.

According to an embodiment of the central tube-tubing connection, the central tube is provided with sealing lips that are provided in the joining area, ensuring a reliable seal. The housing 10 is provided with an inner socket 15, as well as a protruding peripheral protruding latch flange 16 and a cylindrical housing 17 provided for a cover 18. The cover 18 has a cocked configuration and is provided with at least two elements of latch 19, 20. The latch elements are integrated in a pivotable manner with the lid through so-called film hinges, the same being made of plastic together with the lid in a single operative stage. Said locking elements fit over the projecting locking flange 16 of the casing 10. In the left half of the axial section of FIG. 1, the locking element 19 is shown in its open position. In the right half of the axial section, or in the detailed view, the closing element 20 is shown in the closed position. A central tube 22 made of metal or plastic is fixed to the inner tubing 15 of the housing 10. For fixing by means of a form connection of said central tube, the latter has been provided with a bead 23, which engages in a peripheral groove 24 provided in the branch piece 15. With this measure an inadvertent detachment of the central tube is no longer possible. A filtering cartridge 21 is placed on the central tube 22, which carries on its upper front face a radial sealing means, which constitutes a unit with the end disk 40 of the filter element. Said sealing means is constituted by a protruding peripheral bead 25, which is outside the plane of the filter. Said bead 25 surrounds in a hermetic manner the branch piece 15. In the case of this type of seal, a variation of the length of the filter element only has a secondary role. Additionally, this type of seal is extremely reliable also in the case of vibrations and vibrations.

The filter element 21 is supported by its opposite dorsal end by means of integrated buttons 26 against the lid 18. These buttons, which can also be embodied as deformable ribs, serve for the axial attachment of the filter element and for the damping of the filter element. vibrations of the cartridge provided by the opposite dorsal end simply on the central tube 22. Within the central tube 22 a secondary element 27 is provided., which is provided at its front end with a sealing gasket 28 of polyurethane foam. Said front sealing gasket is connected by non-positive connection with the inner branch pipe 15. The rear end of the secondary element 27 is sealed by means of a sealing disk 29 of polyurethane foam. In said end disk 29 a plastic handle has been integrated which serves to allow the manual removal of the secondary element. The secondary element is constituted functionally by a non-woven textile material 31, which is inserted on a support tube 32. The axial force necessary to seal the secondary element in the purified air outlet is applied through the lid 18 and the integrated buttons 26 of the filter element 21 on the sealing disc 29. Since the secondary element 27 is completely surrounded by the central tube 22, there is no danger that during the replacement of the filter cartridge said secondary element is unintentionally removed or the same come off. During the assembly of the filter in its entirety, the secondary element is placed first, the filter cartridge 21 then moving on it and finally the lid is placed 18. By placing the secondary element by its rear end on the filter cartridge 21 and simultaneously by the settling of the filter cartridge 21 against the cover 18 both elements are brought to their correct position when the cover is placed. The foregoing means that a wrong assembly of both elements is not possible. The final position of these elements is achieved by closing the cover 18 placed in the housing 17. The metal-free secondary element can be discarded without problems. The non-woven textile material, the polyurethane foam end discs, the plastic core tube and the handle can be removed by way of thermal example. Since the filtering cartridge 21 has front sealing joints on both front faces, it is possible to clean this filter cartridge by applying gentle blows or by releasing it from the dirt layer without major problems. In this case, the elastic end discs are not damaged, as would be the case, for example, if the end discs were made of sheet metal. Figure 2 illustrates the filter element in a detailed representation. The filter element 21 is constituted by a filter means 33 folded in a zig-zag shape, which can be provided by its inner periphery or outer periphery with a support body. There is also the possibility of constituting the filter element 21 in a self-supporting manner, which is the case in the illustrated element. On the front face, facing the outlet of pure air, an end disk 34 made of thermoplastic elastomer or thermoplastic polyurethane has been applied. Said end disk carries a protruding bead 25 which is outside the plane of the filter. Said bead is in turn provided on its inner part with an annular sealing element 35, which is constituted by the same material as the end disk. Due to the elasticity of the material, a reliable seal is achieved between the impure air side and the purified air side in an armed state. In fact, it is also possible to provide a plurality of annular sealing elements in the bead 25. At the opposite end to the purified air outlet, the filter element 21 with a closed end disk 36 is provided. This disk is also constituted by a thermoplastic elastomer or a thermoplastic polyurethane, the same carrying a plurality of integrated buttons or support elements 26. For the assembly of the filter element 21 the end discs 34, 36 are heated by their facing face to the filter medium 33, by way of example by means of welding heating elements, and being the same, after sufficient heating, applied under pressure on the filter medium. Due to the exactly defined local heating, the depth of penetration of the filter medium into the respective end discs can be determined fairly accurately, thereby also giving the possibility of compensating eventual tolerances in the longitudinal dimension of the filter medium. Due to the above-described structure of the thermoplastic elastomer or thermoplastic polyurethane, the input material for the end discs is particularly reduced, whereby the costs can be substantially reduced, further producing lower costs when recycling the filter cartridge 21.

Claims (6)

Claims

1. Air filter, particularly for purifying combustion air of internal combustion engines, which is constituted by a filtering cartridge substantially free of metals, which is manufactured from a filter medium folded in a zigzag shape and which constitutes a cylinder hollow, having end discs disposed on the front sides of the filter medium and at least one of said end discs being constituted by a thermoplastic elastomer or a thermoplastic polyurethane.

2. Air filter according to claim 1, characterized in that a support body is provided on the inner wall or on the outer wall of the filter medium.

3. Air filter according to claim 1 or 2, characterized in that at least one end disk of the filter cartridge has a concentric collar, which is provided with at least one radial sealing means.

4. Air filter according to at least one of the preceding claims, characterized in that at least one end disk of the filter cartridge has protruding support bodies in the axial direction.

5. Process for manufacturing an air filter, particularly for purifying combustion air for internal combustion engines, comprising a filter cartridge, which is manufactured from a filter medium folded in a zig-zag shape and having a hollow cylindrical shape, characterized in that on at least one of the axial end faces of the filter cartridge there is disposed at least one end disk of thermoplastic elastomer or thermoplastic polyurethane, the end discs being connected with the filter medium through a soldering by heating elements of high temperature and the end disk and / or the filter medium being joined by partial melting.

6. Method according to claim 5, characterized in that the connection of the end disk and the filter medium takes place by means of a butt welding with thermal reflectors.