Filter material and filter element

Abstract

The utility model relates to a filter material (10) for filtering air in a filter element (100) and a filter element comprising the filter material. The filter material (10) is equipped with an inflow-side pre-filter layer (2), an activated carbon layer (3) and a composite layer (1) having at least one membrane. According to the utility model, the layers of materials are connected with each other in a locking manner. Due to the combination of the pre-filter layer and the composite layer with the membrane in the filter material, high dust holding capacity is achieved while achieving high quality factor in an advantageous manner.

Description

Technical Field

[0001] This utility model relates to a filter material, and also to a filter element having such a filter material. Background Technology

[0002] Filters are known from existing technology for filtering fluids, especially air. For this purpose, the filter element is typically housed within a filter housing and through which air flows.

[0003] Various filter elements for filtering cabin air are known from the prior art. For example, DE 10 201 3 011457 A1 describes an cabin air filter element for the cab of agricultural and operational machinery.

[0004] The internal air filter element includes an adsorption filter layer with activated carbon, a fine filter layer for separating aerosols, and a surrounding seal for separating the dirty side from the clean side when installed in the filter housing. This multi-stage filter is also called a multi-level filter. The pleated pre-filter layer protects the adsorption and fine filter layers from high dust concentrations and maintains their functionality for as long as possible. A disadvantage of this structure is that the pre-filter layer requires additional structural space and cannot be compactly configured into the filter element. Utility Model Content

[0005] The purpose of this invention is to provide a filter material that, compared with known filter materials, has a more stable filtration efficiency during use while maintaining the same structural space.

[0006] The objective is achieved by the filter material described below and claimed.

[0007] This utility model relates to a filter material for air filtration in a filter element and having a pre-filter layer, an activated carbon layer, and a composite layer on the inflow side. The composite layer is configured to have at least one membrane layer. According to this utility model, it is advantageous to combine the pre-filter layer, the activated carbon layer as an adsorption layer, and the composite layer with a membrane in one filter material.

[0008] The filter material according to this invention is used for air filtration in a filter element. The filter material has a pre-filter layer on the inflow side designed as a coarse dust filtration layer, an activated carbon layer as an adsorption layer, and a composite layer having a membrane as a mechanical filtration medium. The membrane, as defined below, is a thin layer of fine pores or fine fibers. Thus, depending on the particle size, the membrane can be permeable, semi-permeable, or impermeable. This allows filtration of particles in the micron and submicron range. The membrane can be made of a polymer. Polymer-based membranes typically require additional mechanical reinforcement because such membranes have relatively low inherent stability. This mechanical reinforcement can be achieved through other layers of the filter material. The membrane can be composed, alone or in combination, of, for example, the following polymers: PTFE, PE (also known as LD-PE, HD-PE, and UHMW-PE), PET, PVDF, PA, PLA, and PU.

[0009] According to this invention, the composite layer has at least one membrane on a carrier layer, and the membrane may have a cover layer on its other side. Furthermore, multiple membranes and carrier / cover layers can be combined to form a composite layer (e.g., carrier + membrane + carrier layer + membrane + cover layer). These layer materials are interlocked. The carrier layer may be composed of coarse fibers, and the cover layer may be composed of coarse fibers and / or microfibers.

[0010] According to this invention, the pre-filter layer, activated carbon layer, and composite layer are interconnected in a locking manner. That is, these layers are not connected by co-pleating, i.e., not by jointly folding the layers, but rather by material locking. This type of material locking connection is also called "mutual lamination."

[0011] The material-locked connections can be achieved through lamination or overlay by any type of adhesive (polymer wire, powder, M-Web (hot melt adhesive web), reactive adhesive, or thermal adhesive, such as thermoplastic melt, etc.), hot pressing (calendering with / without melt fiber components), or by ultrasonic welding or ultrasonic calendering. The material-locked connections can exist over the entire surface or in points over the area of ​​the layer.

[0012] Compared to co-pleated connections, material-locked connections offer the advantage of higher mechanical stability. Another advantage is improved temperature stability: after thermal aging of the filter material, a smaller increase in pressure loss can be observed compared to co-pleated filter materials with otherwise identical structures. The filter material with material-locked connections can also be pleated uniformly. Without material-locked connections, typically a maximum of two layers can be co-pleated together. In this case, the additional layers must be pleated individually, resulting in a filter element consisting of two layers: a (individually) pleated layer and a co-pleated layer. However, this type of multi-layered filter element requires more structural space. That is, due to the material-locked connections of all layers, filter media with three or more layers can be achieved, which have lower structural space requirements in subsequent pleating compared to co-pleated filter media.

[0013] The combination of a pre-filtration layer and a membrane-containing composite layer in the filter material achieves both high dust holding capacity and a high quality factor. This material also exhibits favorable properties in its thickness: by using this filter material in a filter, good filtration efficiency can be achieved without increasing pressure loss.

[0014] Compared to coarser fibers, the advantage of using membranes lies in their larger surface area, resulting in improved filtration performance and a longer filter lifespan. This is particularly due to the higher screening effect (retention effect) resulting from the smaller fiber diameter. Unlike electrostatic separation, the effect achieved through mechanical separation is maintained to a high degree throughout the filter's entire operating time. Furthermore, membrane-based filter media exhibit lower pressure loss, leading to lower energy requirements for the filter element.

[0015] The filter material according to this invention has an adsorption layer constructed as an activated carbon layer, that is, the filter material has a layer containing a certain proportion of activated carbon as an adsorbent. A filter element made from this filter material is called a combination filter.

[0016] In a particularly advantageous improvement to the filter media, these layers are joined by bonding using a polyolefin hot melt as a thermoplastic hot melt adhesive. This has the following advantages:

[0017] - Excellent adhesion properties on the substrate to be bonded.

[0018] High thermal stability of 105°C

[0019] - Stability in oxidative decomposition processes

[0020] - High aging stability, and

[0021] - Insignificant effects on fogging and odor.

[0022] The individual layers of the composite layer can also be bonded together using polyolefin hot melt.

[0023] In an improved embodiment of this invention, the pre-filter layer and / or the composite layer in the filter material are electrostatically charged, for example, by corona discharge or high-voltage discharge techniques. This further improves the dust-holding capacity.

[0024] In one possible design of the filter material, the activated carbon layer is equipped with a persistent adhesive mesh. This persistent adhesive mesh, also referred to as a mesh-like adhesive layer, is introduced into the activated carbon layer. To form this adhesive layer, a polyolefin hot melt can be used in the form of filaments with a diameter of 5 to 20 μm constituting the adhesive mesh. The persistent adhesive mesh allows for the advantageous separation of larger dust particles, particularly, thereby protecting the subsequent layers. Another function of the adhesive mesh is to bind and immobilize the adsorbent particles in the activated carbon layer.

[0025] In the improved version of the filter material, the filter material has an additional coarse filtration layer, which can also be called a coarse dust filtration layer. The function of this coarse dust filtration layer is twofold: firstly, to provide a carrier structure for the activated carbon layer or a support structure for the composite layer; and secondly, to facilitate filtration. Thus, the advantages of this filter material are higher stability and higher dust holding capacity. Higher dust holding capacity helps to keep the pressure loss rise of the filter element as low as possible during use, especially despite the presence of highly separated nanofibers. Therefore, viewed in the flow direction, the coarse dust filtration layer can be positioned upstream of the composite layer.

[0026] In possible designs of the filter material, the pre-filtration layer or, if present, the coarse filtration layer forms a carrier and thereby creates a support structure for the activated carbon layer. The activated carbon layer may also consist, in particular, of mutually bonded activated carbon particles.

[0027] Especially for activated carbon layers with a large number of individual activated carbon particles, it is common in the prior art to apply the bulk material of the particles to a support structure and fix them by adhesive. As claimed herein, if a pre-filter layer or a possible coarse filter layer is used as a carrier, the filtration function can still be achieved through the pre-filter layer or the possible coarse filter layer, which further improves the filtration performance of the filter material.

[0028] Different variations of the filter material can be envisioned, and these variations differ in their structure. Here, the structure of the composite layer is uniform, and when viewed in the flow direction, it is as follows: a carrier layer, a membrane, and possibly other layers.

[0029] In the first variant, the filter material has a pre-filter layer on the inflow side, a composite layer on the outflow side, and an activated carbon layer located between the pre-filter layer and the composite layer.

[0030] Therefore, observing the flow direction, the following layer sequence is obtained:

[0031] 1.) Pre-filter layer

[0032] 2.) Activated carbon layer

[0033] 3.) Composite layer

[0034] In the second variant, the filter material has an inflow-side pre-filter layer, an outflow-side coarse filter layer with an activated carbon layer applied thereon, and a composite layer located between the pre-filter layer and the coarse filter layer, wherein the pre-filter layer and the composite layer are configured as units that are materially locked together, for example by means of thermal welding.

[0035] Therefore, observing the flow direction, the following layer sequence is obtained:

[0036] 1.) Pre-filter layer

[0037] 2.) Composite layer

[0038] 3.) Activated carbon layer

[0039] 4.) Coarse filtration layer

[0040] In the third variant, the filter material has: an inflow-side pre-filter layer with an activated carbon layer applied thereon, the activated carbon layer being located downstream of the pre-filter layer; an outflow-side composite layer; and a coarse filter layer located between the pre-filter layer and the composite layer, the coarse filter layer and the composite layer being, in particular, units configured to be materially interlocked and bonded together, for example, with a thermoplastic melt.

[0041] Therefore, observing the flow direction, the following layer sequence is obtained:

[0042] 1.) Pre-filter layer

[0043] 2.) Activated carbon layer

[0044] 3.) Coarse filtration layer

[0045] 4.) Composite layer

[0046] In the fourth variant, there is a pre-filter layer on the inflow side, a coarse filter layer with an activated carbon layer applied upstream thereon, another coarse filter layer, and a composite layer on the outflow side. The other coarse filter layer and the composite layer are specifically configured as units interconnected by material locking, for example, through thermal welding.

[0047] Therefore, observing the flow direction, the following layer sequence is obtained:

[0048] 1.) Pre-filter layer

[0049] 2.) Activated carbon layer

[0050] 3.) Coarse filtration layer

[0051] 4.) Coarse filtration layer

[0052] 5.) Composite layer

[0053] In the second, third, and fourth variations, the material-locked interconnection of units refers to the pre-filter layer and the composite layer, or the coarse filter layer and the composite layer, having already been material-locked together in a prior processing step, and then achieving material-locked connection with other layers in another processing step. The material-locked connection between the pre-filter layer or the coarse filter layer and the composite layer can be performed thermally across the entire surface and / or through point-like layer welding.

[0054] This allows for exceptionally high strength and good processability of the filter material.

[0055] In one possible design of the filter material, the filter material has a gradient structure, such that the porosity of each of the layers—the pre-filter layer, the activated carbon layer, and the composite layer—gradually decreases from the inflow side (dirty gas side) to the outflow side (clean gas side) of the filter material, from one layer to the next. Here, porosity refers to the ratio of the cavity volume of the corresponding nonwoven fabric layer to its total volume. Or in other words, the gradient structure means that, viewed along the flow direction, each of the layers becomes increasingly finer. This filter material provides particularly good dust filtration and has a stable pressure differential over time.

[0056] This utility model also relates to a filter element having a filter material with pleats as described above.

[0057] In possible designs of the filter element, edge bands or frame elements can be mounted on the pleated filter material. These edge bands or frame elements can stabilize the filter element and can also serve as sealing elements relative to the filter housing that houses the filter element.

[0058] This invention also relates to the application of the filter element as described above, which is used as an interior air filter for filtering and purifying the cabin air in vehicles, especially in cars, trucks or buses.

[0059] Provided that this is technically reasonable, the described utility model and its advantageous improvements can also be combined to constitute advantageous improvements of the utility model.

[0060] For other advantages of this invention, as well as advantageous structural and functional designs, please refer to the description of the embodiments with reference to the accompanying drawings. Attached Figure Description

[0061] The present invention will be described in more detail with reference to the accompanying drawings. Corresponding elements and components have the same reference numerals in the drawings. For clarity, scaled-down illustrations are not used.

[0062] The following diagrams illustrate the points:

[0063] Figure 1 A first embodiment of the filter material is shown in a cross-sectional view;

[0064] Figure 2 A second embodiment of the filter material is shown in cross-sectional view;

[0065] Figure 3 A third embodiment of the filter material is shown in cross-sectional view;

[0066] Figure 4 A fourth embodiment of the filter material is shown in cross-sectional view;

[0067] Figure 5 A partial view of the filtered material after pleating is completed;

[0068] Figure 6 A 3D view shows a filter element with filter material. Detailed Implementation

[0069] Figure 1 A first embodiment of the filter material 10 is shown in cross-section. The direction of airflow is indicated by arrow L. The filter material 10 has a pre-filter layer 2 on the inflow side, an intermediate activated carbon layer 3, and a composite layer 1 on the outflow side, the composite layer being configured as a fine filter layer having one or more membranes. The composite layer 1 has multiple layers, namely at least one carrier layer and a membrane, these layers being interconnected in a material-locking manner. However, the composite layer may also consist of multiple carrier layers, membrane layers, and cover layers. Only the cover layer and carrier layer are shown in the figure. Possible specific designs of the composite layer are:

[0070] 1. Carrier layer + membrane

[0071] 2. Carrier layer + membrane + capping layer

[0072] 3. Carrier layer + membrane + carrier layer + membrane

[0073] 4. Carrier layer + membrane + carrier layer + membrane + capping layer

[0074] If multiple membranes and / or multiple carriers are used, these membranes and / or carriers can differ in their performance. Thus, these membranes can, for example, have different filtration efficiencies.

[0075] Other embodiments described below also have this structure of composite layer 1. The pre-filter layer 2, activated carbon layer 3, and composite layer 1 are interlocked using a thermoplastic melt (not shown) material. The capping layer, membrane, and carrier layer of composite layer 1 can also be connected to each other using a thermoplastic melt or by thermal welding.

[0076] Figure 2 A second embodiment of the filter material 10 is shown in cross-section. It includes a pre-filter layer 2 on the inflow side, a coarse filter layer 4 on the outflow side with an activated carbon layer 3 applied thereon upstream, and a composite layer 1 located between the pre-filter layer and the coarse filter layer.

[0077] The pre-filter layer 2 and the composite layer 1 are connected to each other by thermal welding. The composite layer 1, the activated carbon layer 3, and the coarse filter layer 4 are connected to each other by a thermoplastic melt material.

[0078] Figure 3 A third embodiment of the filter material 10 is shown in cross-sectional view. Here, a pre-filter layer 2 on the inflow side, a composite layer 1 on the outflow side, and a coarse filter layer 4 located between the pre-filter layer and the composite layer are used. The coarse filter layer has an activated carbon layer 3 applied thereon, which is disposed upstream of the coarse filter layer 4.

[0079] The coarse filter layer 4 and the composite layer 1 are interlocked using a thermoplastic melt material. The pre-filter layer 2, the activated carbon layer 3, and the coarse filter layer 4 are interlocked using a thermoplastic melt material.

[0080] Figure 4 A fourth embodiment of the filter material 10 is shown in cross-sectional view. (Compared with...) Figure 3 The proposed solution differs from the previous one, which uses a different filter layer, namely a coarse filter layer 4 located upstream of the composite layer 1.

[0081] The coarse filter layer 4 and the composite layer 1 are connected to each other by thermal welding. The pre-filter layer 2, the activated carbon layer 3, and the two coarse filter layers 4 are connected to each other by thermoplastic melt material.

[0082] Regardless of the multi-layered structure of the filter material, Figure 5A partial view of the filter material 10 after pleating is completed is shown. The folded edge is exemplarily marked with 11.

[0083] Figure 6 A perspective view shows a filter element 100 having filter material 10. It has the ability to... Figures 1 to 4 Designed as described in the text and already as Figure 5 The filter element 100 of the pleated filter material 10 shown has an edge band 20 mounted on the pleated filter material 10. The edge band helps to stabilize the filter element 100 and can achieve a seal relative to the filter housing, which is not shown here.

[0084] List of reference numerals

[0085] 1. Composite layer with membrane

[0086] 2 Pre-filter layer

[0087] 3 Activated Carbon Layer

[0088] 4 coarse filter layers

[0089] 10 Filter Material

[0090] 11 Folded Edges

[0091] 20 edge band

[0092] 100 filter elements

[0093] L is the direction of airflow.

Claims

1. A filter material for air filtration in a filter element (100) and having an inflow-side pre-filter layer (2), an activated carbon layer (3), and a composite layer (1), the composite layer being configured to have at least one membrane layer, characterized in that, The pre-filter layer (2), the activated carbon layer (3), and the composite layer (1) are interconnected in a locked manner.

2. The filter material of claim 1, wherein, The pre-filter layer (2) and / or the composite layer (1) are electrostatically charged.

3. The filter material according to claim 1 or 2, characterized in that, The activated carbon layer (3) is equipped with a durable adhesive mesh.

4. The filter material according to claim 1 or 2, characterized in that The filter material (10) has an additional coarse filter layer (4).

5. The filter material of claim 4, wherein, The pre-filter layer (2) or the coarse filter layer (4) forms a carrier for the activated carbon layer (3).

6. The filter material according to claim 1 or 2, characterized in that, The activated carbon layer (3) is composed of activated carbon particles that are bonded together.

7. The filter material according to claim 1 or 2, characterized in that, The filter material (10) has the following structure: a pre-filter layer (2) on the inflow side, a composite layer (1) on the outflow side, and an activated carbon layer (3) located between the pre-filter layer and the composite layer.

8. The filter material according to claim 1 or 2, characterized in that, The filter material (10) has the following structure: a pre-filter layer (2) on the inflow side, a coarse filter layer (4) on the outflow side with an activated carbon layer (3) applied thereon, and a composite layer (1) located between the pre-filter layer and the coarse filter layer.

9. The filter material according to claim 8, characterized in that, The pre-filter layer (2) and the composite layer (1) are configured as units that are materially locked together.

10. The filter material of claim 1 or 2, wherein, The filter material (10) has the following structure: a pre-filter layer (2) on the inflow side, a composite layer (1) on the outflow side, and at least one coarse filter layer (4) located between the pre-filter layer and the composite layer, and an activated carbon layer (3).

11. The filter material of claim 10, wherein, The activated carbon layer (3) is applied upstream to the first coarse filter layer (4), and additionally the second coarse filter layer (4) and the composite layer (1) are configured as units that are materially locked together.

12. The filter material of claim 1 or 2, wherein, The filter material has a gradually changing structure in each layer.

13. A filter element having a filter material according to any one of claims 1 to 12, wherein, The filter material is pleated and has edge bands (20) or frame elements on the pleated filter material.

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