DE102020127821A1 - air filter - Google Patents

Abstract

The invention relates to a filter medium (1) comprising a coarse filter layer (2) and a fine filter layer (3), the coarse filter layer (2) comprising knitted fabric (4) and/or knitted fabric, the fine filter layer (3) comprising nanofibers, a membrane, natural fibers and / or comprises melt-spun microfibers, and the fine filter layer (3) is arranged on the coarse filter layer (2).

Description

technical field

The invention relates to a filter medium comprising a coarse filter layer and a fine filter layer. The invention also relates to the use of the filter medium for cleaning an air flow. In addition, the invention relates to a method for producing an air filter and a method for cleaning an air flow with an air filter.

Background of the Invention

Air filters have been known for decades and are used to filter out aerosols or unwanted suspended matter and particles such as pathogens, pollen, dust or gases from an air flow and/or ambient air. As a rule, filtering separators are used as air filters, which remove the aforementioned suspended matter from the air by means of a filtering medium. Air filters are used in internal combustion engines, ventilation systems, extraction systems, dedusting systems, household appliances such as vacuum cleaners, etc.

Several different filters are often arranged one behind the other in order to achieve a high separation capacity, for example for the purpose of high air quality. The installation space required for the filters increases with the number of filters. In addition, as the number of filters increases, so does the energy required to drive a blower that is correspondingly powerful for the number of filters.

Description of the invention

Proceeding from this situation, it is an object of the present invention to specify an improved filter medium, a corresponding method and an air filter in order to clean an air flow.

The object of the invention is solved by the features of the independent claims. Advantageous configurations are specified in the dependent claims.

Accordingly, the object is achieved by a filter medium comprising a coarse filter layer and a fine filter layer, wherein
the coarse filter layer comprises knitted and/or knitted fabrics,
the fine filter layer comprises nanofibers, natural fibers, a membrane and/or melt-spun microfibers, and
the fine filter layer is arranged on the coarse filter layer.

An essential aspect of the invention is that a fine filter layer is provided on a carrier side of the coarse filter layer. An air stream preferably first flows through the coarse filter layer, through which coarse dust can be filtered out of the air stream and which stores the coarse dust that has been filtered out in the coarse filter layer. The air flow filtered in this way then preferably flows through the fine filter layer, through which fine separation takes place. As a result, the proposed filter medium can be easily and cost-effectively manufactured to achieve a high level of separation of undesirable aerosols or suspended matter and particles such as pathogens, pollen, dust or gases compared to designs known from the prior art. The filter medium can be used as an air filter in building applications, for building ventilation and ventilation, in industrial applications, in internal combustion engines, in ventilation systems, in extraction systems, in dedusting systems, in household appliances such as vacuum cleaners, etc., to remove the aforementioned aerosols or unwanted suspended particles from the air filter to filter out the air flow flowing through, in particular with simultaneous pre-separation of coarse particles.

The coarse filter layer and the fine filter layer preferably have a rectangular and/or equally large extension and/or are arranged congruently one above the other. A knitted fabric is understood to mean, in particular, a textile fabric which is industrially produced from thread systems by stitch formation, for example on a knitting machine. A knitted fabric is understood to mean, in particular, a fabric knitted in a loop-like manner from yarn. The fabric and/or the yarn can comprise natural fibers such as plant fibers and/or man-made fibers such as fibers made from natural polymers, fibers made from synthetic polymers and/or fibers made from inorganic substances.

The nanofibers, the natural fibers, the membrane and/or the microfibers preferably have a fiber diameter of less than 500 nm, preferably 200 nm. The membrane is preferably not described by a fiber diameter but by the pore size, which is preferably between 1 μm and 10 μm. Likewise, the fiber diameter can be between 50 and 300 nm. Melt-spun microfibers can be produced by means of a thermal and/or by means of an ultrasonic process, the fibers being passed between two rollers, for example, at least one of which is heated to the melting temperature of the fibers. The fine filter layer is preferably arranged stationary on the coarse filter layer. Stationary means in particular that the fine filter layer is arranged in a non-slip manner on the coarse filter layer and/or is fixed in its position relative to the coarse filter layer in particular in a dimensionally stable manner. The fine filter layer can also be loose, be arranged slipped and / or not fixed on the coarse filter layer.

According to a further preferred embodiment, the filter medium comprises a carrier layer arranged on the coarse filter layer, with the nanofibers, the membrane, natural fibers and/or melt-spun microfibers of the fine filter layer being applied to the carrier layer. The carrier layer preferably comprises a scrim. Scrim is understood to mean, in particular, a gauze fabric which is designed in particular as an air-permeable and/or light, semi-transparent fabric in a leno, mock leno or plain weave, with threads in a leno weave being offset less than in the two latter types. The scrim can be formed from polyester.

According to another preferred embodiment, the nanofibers include polyvinylidene fluoride or chloride, PVA, polyvinyl acetate, nylon, polyurethane, polymers and/or a core of PET, polyethylene terephthalate, and a sheath of PE, polyethylene, the natural fibers include cellulose and/or include melt-spun Microfibers meltblown. Fibers with a core made of PET and a sheath made of PE are also referred to as bi-component, BiCo, fibers, whereby the polymers can have different softening or melting temperatures. Preferably, the melting temperature of the core is higher than that of the sheath to melt at a certain temperature impact to create bonding points between the respective core fibers. The natural fibers can include cellulose or cellulose with synthetic fiber components. The membrane can be made of PTFE, polytetrafluoroethylene.

The term meltblown is understood to mean, in particular, nonwovens made from fibers which are spun from molten polypropylene and/or polymer passing through nozzles, are stretched to the point of tearing by means of hot air streams and are formed by direct deposition. Such webs, also referred to as melt-blown media, usually have longer continuous fibers similar to staple fibers or consist of a mixture with continuous fibers or consist entirely of continuous fibers. If nonwovens are made from fibers spun from polymer melts passing through nozzles, are knitted by means of cold air and/or mechanically and are formed by direct laying, they are also referred to as spunbonded nonwovens or generally as spunbond media. The media designed from nonwovens are usually made up of filaments or endless fibers. The fine filter layer can also include synthetic fibers such as PES, PET, PP, PA, PBT, PTFE etc. or a combination of the aforementioned filter media.

According to a preferred development, the knitted and/or knitted fabric is designed as a three-dimensional structure and/or the knitted and/or knitted fabric comprises pile threads. The knitted fabric and/or knitted fabric is preferably designed as a spacer fabric and/or as a three-dimensional spacer knitted structure. A spacer knitted fabric and/or a spacer knitted fabric represents in particular a double-faced knitted fabric and/or textile in which the preferably warp-knitted cover surfaces are kept at a distance by spacer connecting threads, so-called pile threads. The pile threads are used in particular for separating coarse dust and storing it deep.

A monofilament, for example comprising polyester, can be used as spacer connecting threads. The spacer connecting threads are preferably laid in a cross shape between the in particular textile cover surfaces with a crossing angle of approximately 45° in order to ensure good displacement resistance of the cover surfaces relative to one another and to prevent the spacer fabric from tilting under pressure. More preferably, the spacer connecting threads can be stabilized by finishing processes such as thermal treatment, in order to ensure permanent bending elasticity. The knitted fabric and/or the knitted fabric or the coarse filter layer preferably has a thickness of ≧1, 2, 3, 5, 10, 15, 20 or 25 mm and/or ≦5, 10, 20, 30, 40, 50 or 65 mm up. The fine filter layer preferably has a thickness of 1%, 2%, 5%, 10%, 20%, 30%, 40% or 50% of the thickness of the coarse filter layer. The fine filter layer preferably has a thickness of 100 μm, 200 μm or 300 μm.

According to a further preferred embodiment, the fine filter layer and the coarse filter layer are welded and/or glued together and/or the fine filter layer is sprayed and/or placed onto the coarse filter layer. The welding preferably takes place by means of a thermal process. Such a configuration allows the fine filter layer to be fixed in a particularly simple manner on the one hand and in a particularly dimensionally stable manner on the other hand. In particular, spraying on allows the filter medium to be produced in a simple and cost-effective manner.

According to a preferred development, the filter medium has a first cover layer and a second cover layer, with the first cover layer and the second cover layer enclosing the knitted fabric and/or the knitted fabric on both sides and the fine filter layer being arranged on the second cover layer. Preferably, the first cover layer and the second cover layer completely cover the knitted fabric and/or the knitted fabric. More preferably, the coarse filter layer has the first cover layer and the second cover layer on and/or the coarse filter layer, the first cover layer and the second cover layer are made in one piece. Even more preferably, the first cover layer and the second cover layer are provided in a stationary manner on the knitted fabric and/or on the knitted fabric, in particular glued, welded and/or sewn to it. The first cover layer and the second cover layer are particularly preferably designed to be air-permeable.

Likewise, the first cover layer can be impermeable to air and the second cover layer can be designed to be air-permeable.

According to a further preferred embodiment, the first cover layer and/or the second cover layer comprises a gauze fabric. The gauze fabric, also known as scrim or gauze, is designed in particular as an air-permeable and/or light, semi-transparent fabric in leno, mock leno or plain weave, with threads in leno weave being able to be offset less than in the latter two types. More preferably, the gauze fabric is made of polyester.

According to a preferred development, the coarse filter layer and the fine filter layer each have a longitudinal side arranged congruently to one another and/or the longitudinal side of the coarse filter layer and/or the longitudinal side of the fine filter layer is closed, in particular hermetically sealed. The respective longitudinal side is preferably welded and/or glued. As a result of the closure, the air flow flowing in particular on the non-closed longitudinal side in the transverse direction into the filter medium first flows through the coarse filter layer and then via the second cover layer into the fine filter layer. More preferably, the two longitudinal sides are closed together and/or closed along their entire length.

According to a further preferred embodiment, the coarse filter layer and the fine filter layer are spirally wound up in several layers. The individual layers are preferably in contact with one another. The wound layers preferably have a diameter of 5, 10, 15 or 20 cm, with a core being able to be omitted. In relation to the winding, the fine filter layer can be arranged on the outside or inside in relation to the coarse filter layer. The individual layers can be glued and/or welded to one another.

The object is also achieved by using an air filter as described above in a motor vehicle for cleaning an air flow, the air flow flowing into the air filter in the direction of a transverse side of the air filter. The air flow preferably first flows into the coarse filter layer for filtering out coarse dust and then flows through the fine filter layer for filtering out fine dust. The proposed filter allows an air flow supplied, for example, to a vehicle interior and/or an engine of the vehicle to be cleaned effectively.

• ortsfestes Anordnen einer Feinfilterlage umfassend Nanofasern, Naturfasern, eine Membran und/oder schmelzgesponnene Mikrofasern auf einer Grobfilterlage umfassend Gewirk und/oder Gestrick.

In addition, the object is achieved by a method for producing an air filter, with the step:

• stationary arrangement of a fine filter layer comprising nanofibers, natural fibers, a membrane and/or melt-spun microfibers on a coarse filter layer comprising knitted and/or knitted fabric.

• Aufbringen der Nanofasern, der Membran, Naturfasern und/oder schmelzgesponnene Mikrofasern der Feinfilterlage auf einer Trägerlage und Anordnen der Trägerlage auf der Grobfilterlage, und/oder
• ortsfestes Anordnen mittels miteinander Verschweißen und/oder Verkleben der Feinfilterlage und der Grobfilterlage und/oder aufspritzen der Feinfilterlage auf die Grobfilterlage.

According to a preferred development, the method includes the step:

• Applying the nanofibers, the membrane, natural fibers and/or melt-spun microfibers of the fine filter layer to a carrier layer and arranging the carrier layer on the coarse filter layer, and/or
• stationary arrangement by means of welding and/or gluing together the fine filter layer and the coarse filter layer and/or spraying the fine filter layer onto the coarse filter layer.

• Kongruentes Anordnen einer Längsseite der Grobfilterlage und einer Längsseite der Feinfilterlage übereinander und/oder Verschließen der Längsseite der Grobfilterlage und/oder der Längsseite der Feinfilterlage, und/oder
• Spiralförmiges Aufwickeln der Grobfilterlage und der Feinfilterlage in mehreren Lagen zum Erhalten eines Luftfilters.

According to yet another preferred development, the method includes the step:

• Congruent arrangement of a longitudinal side of the coarse filter layer and a longitudinal side of the fine filter layer one above the other and/or closing the longitudinal side of the coarse filter layer and/or the longitudinal side of the fine filter layer, and/or
• spirally winding the coarse filter sheet and the fine filter sheet in multiple layers to obtain an air filter.

• Einströmen des Luftstroms in Richtung einer Querseite und/oder eine Längsseite des Filtermediums in das Filtermedium.

Finally, the object is achieved by a method for cleaning an air flow with a filter medium as described above, with the step:

• Inflow of the air flow in the direction of a transverse side and/or a longitudinal side of the filter medium into the filter medium.

Further configurations and advantages of the method result for the person skilled in the art in analogy to the air filter described above.

character list

The invention is explained in more detail below with reference to the accompanying drawings using preferred exemplary embodiments.

• 1 eine schematische perspektivische Ansicht eines Filtermediums gemäß einem bevorzugten Ausführungsbeispiel der Erfindung,
• 2 eine schematische Schnittansicht des Filtermediums gemäß dem bevorzugten Ausführungsbeispiel der Erfindung, und
• 3 eine schematische Schnittansicht des spiralförmig aufgerollten Filtermedium als Luftfilter gemäß dem bevorzugten Ausführungsbeispiel der Erfindung.

Show in the drawings

• 1 a schematic perspective view of a filter medium according to a preferred embodiment of the invention,
• 2 a schematic sectional view of the filter medium according to the preferred embodiment of the invention, and
• 3 a schematic sectional view of the spirally rolled filter medium as an air filter according to the preferred embodiment of the invention.

Detailed description of the exemplary embodiments

1 shows a schematic perspective view of a filter medium 1 according to a preferred embodiment of the invention, while 2 a schematic sectional view of the filter medium 1 according to 1 indicates. Finally shows 3 a schematic sectional view of the spirally rolled-up filter medium 1 as an air filter 9 according to 1 and 2 .

The filter medium 1 has a coarse filter layer 2 as a three-dimensional structure for depth filtration and a fine filter layer 3 as a functional layer for fine filtration, and is used to clean an air flow flowing through the filter medium 1 . The filter medium 1 described can be used, for example, to clean air of undesirable suspended matter.

The coarse filter layer 2 is designed as a spacer fabric 4, with warp-knitted upper and lower cover surfaces 5 being kept at a distance by spacer connecting threads, so-called pile threads 6. A first upper cover layer 7 and a second lower cover layer 8 are placed on the cover surfaces 5 and in this way enclose the spacer fabric 4 touching on both sides. The upper cover layer 7 is designed as an air-permeable gauze fabric and the lower cover layer 8 is designed as an air-impermeable gauze fabric, a so-called scrim. Alternatively, the coarse filter layer 2 can comprise another knitted fabric, a knitted fabric, another three-dimensional structure or a combination thereof. The lower cover layer 8 can also be designed to be air-permeable, for example as an air-impermeable gauze fabric.

The fine filter layer 3 is glued to the coarse filter layer 2 or the upper cover layer 7 so that it touches and is thus fixed in place on the coarse filter layer 2 . Likewise, the fine filter layer 3 can be sprayed and/or placed onto the coarse filter layer 2 or thermally fused with it. The fine filter layer 3 includes nanofibers made of polyethylene. Likewise or additionally, the fine filter layer 3 can include natural fibers such as cellulose and/or melt-spun microfibers such as meltblown or a membrane made of PTFE. The fine filter layer 3 has a significantly smaller thickness than the coarse filter layer 2 .

The fine filter layer 3 and the coarse filter layer 2 each have a congruent rectangular extension with, for example, a transverse width of 10 cm and a longitudinal length of 100 cm. To produce the filter medium 1, the fine filter layer 3 and the coarse filter layer 2 are initially arranged congruently one above the other and, for example, glued together. A respective longitudinal side of the same length of the fine filter layer 3 and the coarse filter layer 2 is sealed by welding so that air cannot escape from the filter medium 1 in the transverse direction through the longitudinal side in question.

The fine filter layer 3 and coarse filter layer 2 connected to one another in this way are wound up spirally in several layers along their long sides, so that the fine filter layer 3 and the coarse filter layer 2 of one layer come to rest touching the fine filter layer 3 and the coarse filter layer 2 of the next layer, as in 3 shown to obtain an air filter 9. The winding direction is arbitrary, so that the fine filter layer 3 is on the inside, as in 3 shown, or may be outside. To clean an air flow, it flows on the unclosed long side in the transverse direction into the filter medium 1 into the coarse filter layer 2 and, after flowing through the fine filter layer 3, escapes radially from the air filter 9. In the case of the wound layers, the long sides can also be closed alternately, in particular per turn to achieve a kind of zigzag flow.

The exemplary embodiments described are merely examples that can be modified and/or supplemented in many ways within the scope of the claims. Each feature described for a particular embodiment can be used on its own or in combination with other features in any other embodiment. Each feature described for an embodiment of a particular category can also be used in a corresponding manner in an embodiment of another category.

Reference List

1

filter medium

2

coarse filter layer

3

fine filter layer

4

knitted fabric

5

top surfaces

6

pile threads

7

First top layer

8th

Second top layer

9

air filter

10

backing layer

Claims (15)

Filter medium (1) comprising a coarse filter layer (2) and a fine filter layer (3), wherein the coarse filter layer (2) comprises knitted fabric (4) and/or knitted fabric, the fine filter layer (3) comprises nanofibers, a membrane, natural fibers and/or melt-spun microfibers, and the fine filter layer (3) is arranged on the coarse filter layer (2). Filter medium according to the preceding claim, with a carrier layer (10) arranged on the coarse filter layer (2), the nanofibers, the membrane, natural fibers and/or melt-spun microfibers of the fine filter layer (3) being applied to the carrier layer (10). Filter medium (1) according to any one of the preceding claims, wherein the nanofibers comprise polyvinylidene fluoride or chloride, PVA, nylon and/or polyurethane, the natural fibers comprise wood pulp and/or the microfibers comprise meltblown meltblown. Filter medium (1) according to one of the preceding claims, wherein the knitted fabric (4) and/or knitted fabric is designed as a three-dimensional structure and/or the knitted fabric (4) and/or knitted fabric comprises pile threads (6). Filter medium (1) according to one of the preceding claims, wherein the fine filter layer (3) and the coarse filter layer (2) are welded and/or glued together and/or the fine filter layer (3) is sprayed onto the coarse filter layer (2). Filter medium (1) according to one of the preceding claims, with a first cover layer (7) and a second cover layer (8), the first cover layer (7) and the second cover layer (8) having the knitted fabric (4) and/or the knitted fabric on both sides border and the fine filter layer (3) is arranged on the second cover layer (8). Filter medium (1) according to the preceding claim, wherein the first cover layer (7) and/or the second cover layer (8) comprises a gauze fabric. Air filter (9) with a filter medium (1) according to one of the two preceding claims. Air filter (9) with a filter medium (1) according to one of the preceding filter medium claims, wherein the coarse filter layer (2) and the fine filter layer (3) each have a longitudinal side arranged congruently to one another and/or the longitudinal side of the coarse filter layer (2) and/or the long side of the fine filter layer (3) is closed. Air filter (9) according to one of the preceding air filter claims, wherein the coarse filter layer (2) and the fine filter layer (3) are spirally wound up in several layers. Use of an air filter (9) according to one of the preceding three claims for cleaning an air flow, the air flow flowing into the air filter (9) in the direction of a transverse side of the air filter (9). Method for producing a filter medium (1), with the step: Arranging a fine filter layer (3) comprising nanofibers, a membrane, natural fibers and/or melt-spun microfibers on a coarse filter layer (2) comprising knitted fabric (4) and/or knitted fabric. Method for producing a filter medium (1) according to the preceding method claim, with the step: Applying the nanofibers, the membrane, natural fibers and/or melt-spun microfibers of the fine filter layer (3) to a carrier layer (10) and arranging the carrier layer (10) on the coarse filter layer (2), and/or Arranging by welding and/or gluing together the fine filter layer (3) and the coarse filter layer (2) and/or spraying the fine filter layer (3) onto the coarse filter layer (2). Method for producing a filter medium (1) and/or an air filter (9) according to one of the preceding method claims, with the step: Congruent arrangement of a longitudinal side of the coarse filter layer (2) and a longitudinal side of the fine filter layer (3) one above the other and/or closing the longitudinal side of the coarse filter layer (2) and/or the longitudinal side of the fine filter layer (3), and/or Spirally winding the coarse filter sheet (2) and the fine filter sheet (3) in multiple layers to obtain the air filter (9). Method for cleaning an air flow with a filter medium (1) according to one of the preceding air filter claims, with the step: Inflow of the air flow in the direction of a transverse side and/or longitudinal side of the filter medium (1) into the filter medium (1).

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