Filter element with bellows recessed into each other

The invention relates to a filter element according to the preamble of claim 1.

State of the art

Numerous filters are known from the prior art which implement particle filtration and odor filtration or gas adsorption of fluid flows, in particular of air flows.

The <patcit id="pcit0001" dnum="EP3015155A1"><text>EP 3 015 155 A1</text></patcit> shows a multilayer filter. The filter has two particle-filtering nonwoven layers and a gas-adsorbing activated carbon layer in between.

The <patcit id="pcit0002" dnum="EP2684591A1"><text>EP 2 684 591 A1</text></patcit> shows a multi-stage filter. The cabin air filter element comprises an upstream pre-filter layer for separating dust, an adsorption filter layer, comprising activated carbon, for separating gases and a fine filter layer for separating aerosols, and a circumferential seal for separating the raw gas side from the clean gas side when installed in a filter housing. The filter layers are arranged one above the other, that is, connected in series with one another and connected with a side band.

The difficulty with multi-layer filters is that the filter areas of all layers are the same. However, a larger filter surface would often be advantageous for particle filtration than for odor filtration or gas adsorption.

The difficulty with multi-stage filters is to accommodate sufficient filter surface in the space available. In particular, a larger filter surface is often required for particle filtration than for odor filtration or gas adsorption.

Task

The object of the present invention is to create a filter element in which the size of the filter surfaces is optimized for a specific filtration task with a given installation space. A further object is to create a filter element in which the filter area available for particle filtration is larger than the filter area available for odor filtration or gas adsorption.

Technical solution

This object is achieved by a filter element having the features of claim 1.

According to the invention, it has been recognized as advantageous to allow several bellows of a filter element to dip into one another.

The filter element according to the invention is used to filter a fluid flow, in particular an air flow. It has a first bellows and at least one further bellows, each bellows being formed by a filter medium which is provided with a plurality of folds. Between every two adjacent folding edges of the respective bellows there are folding surfaces which can also be referred to as folding sections. The sum of all folded surfaces forms a filter surface of the filter medium. The distance between two adjacent fold edges, which are separated from one another by a fold section, is referred to below as the fold height. A respective folded edge of the bellows forms either a fold mountain or a fold valley. A respective bellows has an upper edge and a lower edge, the distance between the upper edge and the lower edge of the bellows being described by the height of the bellows, which thus also corresponds to the difference in height between the highest fold mountain and the deepest fold valley. Advantageously, the first bellows and the at least one further bellows are arranged in such a way that the at least one further bellows is immersed in the first bellows. The arrangement is such that the lower edge of the at least one further bellows is lower than the upper edge of the first bellows. Such a configuration of the filter element has the advantage that the height of the filter element is less than the sum of the heights of the bellows. A filter element is thus created, the space requirement of which is lower in terms of height compared to the usual arrangement of bellows in multi-stage filters. Another advantage of the filter element according to the invention is that the size of the filter surfaces of the first bellows and at least one further bellows can be designed independently of one another. Precisely because the at least one further bellows is immersed in the first bellows, it can have a larger number of folded edges and folded surfaces and thus also a larger filter surface. For example, if the first bellows is used for odor filtration or Gas adsorption and the at least one further bellows for particle filtration, the filter surface available for particle filtration can be made larger.

In an advantageous embodiment variant of the filter element according to the invention, the folding surfaces of the first bellows and the at least one further bellows are arranged at a distance from one another, ie they do not touch.

Surprisingly, it was found that with such a filter element, thanks to the larger filter surface, not only the degree of separation from particles to be filtered, such as fine dust, can be increased, but the pressure loss of the filter element can also be reduced at the same time. The invention also comprises filter elements which, in addition to the first bellows and the at least one further bellows, have a third bellows, the third bellows dipping into the further bellows.

In a first variant of the filter element according to the invention, the fold heights of a respective bellows are uniform. Such a bellows can be manufactured particularly simply and inexpensively using the known pleating processes. In an alternative embodiment, the fold heights are non-uniform in the at least one further bellows. This enables the at least one further bellows to plunge deeper into the first bellows. In this way, the overall height of the filter element can advantageously be kept particularly low.

The first bellows and the at least one further bellows can have different fold heights. This is particularly advantageous and therefore preferred, since different filter surfaces of the first bellows and at least one further bellows can be realized in this way.

In an advantageous embodiment of the filter element, the bellows have different heights. As a result, the available filter surface of a respective bellows can be designed more freely.

In an advantageous embodiment of the filter element, fold valleys of the at least one further bellows are located between two respective fold surfaces of the first bellows. In a special case of this embodiment, all of the fold valleys of the at least one further bellows are located between two respective fold surfaces of the first bellows.

In a particularly advantageous and therefore preferred development of the filter element according to the invention, an edge band is provided on at least one side surface of the filter element, with which the first bellows and the at least one further bellows are each materially connected. Ie the edge band is attached to the first bellows and the at least one further bellows. An edge band is also understood here to be an edge strip, that is to say a stabilizing flat element. The side surface of the filter element means that side which does not extend in the direction of the folded edges and is adjacent to the zigzag-shaped edges of the filter medium, that is to say at the end of the folded edges. The material connection can in particular be implemented by gluing, for example using a hot-melt adhesive.

In a further development, a strip-shaped engagement element can also be applied to at least one edge band for engaging the bellows, which at least partially rests with its lower edges on the folded surfaces of the first bellows and with its upper edges on the fold valleys of the at least one further bellows. The engagement element can in particular be designed in the form of a double comb, with a first tooth-shaped comb on its lower edge, which faces and is assigned to the first bellows, and with a further tooth-shaped comb on its upper edge, which faces and is assigned to the further bellows. The positioning of the first bellows and the further bellows in relation to one another is thus determined in an advantageous manner and unwanted contact with the folding surfaces is prevented.

The first bellows and the at least one further bellows of the filter element described above can be formed from different filter media. In this way, the filtration performance of the filter element can advantageously be adapted particularly well to the requirements and matched to the intended use of the filter element. The filter medium of at least one bellows can have a particle filtration layer made of nonwoven fabric.

The filter medium of at least one bellows can have at least one adsorption layer, for example comprising activated carbon.

The filter medium of at least one bellows can have at least one impregnated filtration layer.

The invention also relates to the use of such a filter arrangement in a motor vehicle, for example in a commercial vehicle or a car, for indoor air filtration. The filter arrangement can be used both in recirculation mode and in fresh air mode.

Alternatively, the invention relates to the use of such a filter arrangement in a room air purifier such as that used in living spaces.

The described invention and the described advantageous developments of the invention also represent advantageous developments of the invention in combination with one another - insofar as this is technically sensible.

With regard to further advantages and embodiments of the invention which are advantageous in terms of construction and function, reference is made to the subclaims and the description of exemplary embodiments with reference to the accompanying figures.

Embodiment

The invention will be explained in more detail with reference to the attached figures. Corresponding elements and components are provided with the same reference symbols in the figures. In favor of a better clarity of the figures, a representation true to scale has been dispensed with. It show in a schematic representation<dl id="dl0001" compact="compact"><dt>Fig. 1a</dt><dd>a side view of a bellows</dd><dt>Figure 1b</dt><dd>a top view of a bellows</dd><dt>Fig. 2a</dt><dd>a first embodiment of a filter element</dd><dt>Figure 2b</dt><dd>another version of a filter element</dd><dt>Fig. 3</dt><dd>another version of a filter element</dd><dt>Fig. 4</dt><dd>another version of a filter element</dd><dt>Fig. 5</dt><dd>a detail representation of a plan view of a filter element with filter holder</dd></dl>

In the filter element 100 according to the invention for filtering a fluid flow L with a first bellows 11 and at least one further bellows 12, the at least one further bellows 12 plunges into the first bellows 11.

For a better understanding of the structure of the bellows 11, 12 and their dimensions, see the <figref idref="f0001"><u>Figures 1a and 1b</u></figref> each a bellows 11, 12 shown in a view or in a plan view. In the view of<figref idref="f0001">Fig. 1a</figref> it can be seen that a filter medium 1 is provided with folded edges 2 and thus forms a bellows 11, 12. A respective fold edge 2 forms either a fold mountain 4 or a fold valley 5. The distance between two fold edges 2 and thus also the distance between a fold mountain 4 and a fold valley 5 is referred to as fold height 6 and is marked with a double arrow. The area which lies between two folding edges 2 is the folding area 3, which can also be referred to as a folding section. A folding surface 3 is in<figref idref="f0001">Figure 1b</figref> highlighted in gray for clarity.

In <figref idref="f0002"><u>Fig. 2a</u></figref> a first variant of the filter element 100 according to the invention is shown. The filter element 100 has a first bellows 11 and a second bellows 12 through which a fluid flow L, here an air flow, flows. The direction of flow of the fluid flow L is indicated by an arrow. The second, further bellows 12 dips into the first bellows 11 in such a way that the lower edge U of the further bellows 12 is lower than the upper edge O of the first bellows. This achieves, on the one hand, that the total height of the filter element 100 is less than the sum of the height H1 of the first bellows 11 and the height H2 of the further bellows 12. If the height H1 is 20 mm, for example, and the height H2 is 30 mm, for example, then there is no total height of 50 mm but a lower total height of the filter element 100 of only 45 mm.

In the illustrated embodiment, two fold valleys of the further bellows 12 lie between two fold surfaces 3 each of the first bellows 11. That is, the further bellows 12 has a narrower fold than the first bellows 11 and thus a larger filtration area.

The filter medium 1 of the first bellows 11 can have an adsorption layer, for example comprising activated carbon, so that an activated carbon filter layer is formed by the first bellows 11. The filter medium 1 of the further bellows 12 can have a particle filtration layer made of nonwoven, so that the further bellows 12 forms a particle filter layer.

In <figref idref="f0003"><u>Figure 2b</u></figref> a filter element 100 of the same construction is shown. In addition, an engagement element 9 is provided. The engagement element 9 is designed in the shape of a double comb and rests with its first tooth-shaped comb on its lower edge against the folding surfaces 3 of the first bellows 11. With its further tooth-shaped ridge on its upper edge, the engagement element 9 rests against the fold valleys 5 of the further bellows 12. The engagement element thus has the effect that the positioning of the first bellows 11 and the further bellows 12 relative to one another is fixed and undesired displacements of the first bellows 11 and the further bellows 12 relative to one another are prevented. The engagement element 9 can therefore also be referred to as a spacer.

While the embodiments of <figref idref="f0002">Figures 2a</figref> and <figref idref="f0003">2 B</figref> each have uniform folds, ie the fold heights of a respective bellows 11, 12 are each uniform, shows the embodiment according to <figref idref="f0004"><u>Fig. 3</u></figref> irregular folds. The fold heights 6 of the first bellows 11 are also uniform. However, the fold heights 6 of the further bellows 12 alternate. This enables the further bellows 12 to dip deeper into the first bellows 11. The overall height of the filter element 100 can thus be further reduced. If the height H1 of the first bellows 11 is 30 mm, for example, and the height H 2 of the further bellows 12 is 25 mm, for example, a total height of 35 mm is possible, which is well below the sum of the two individual heights H1 + H2 of 55 mm. In this example, too, the first bellows 11 can form an activated carbon filter layer and the further bellows 12 can form a particle filter layer.

Also in the embodiment according to <figref idref="f0005"><u>Figures 4a and 4b</u></figref> the further bellows 12 does not have uniform pleat heights 6 but alternating pleat heights 6. This enables a fold valley 5 of the further bellows 12 to alternate between two fold surfaces 3 of the first bellows 11 and the next fold valley 5 of the further bellows 12 on the fold mountain 4 of the first bellows rests. In this embodiment, too, the overall height of the filter element 100 is lower than the sum of the height H1 of the first bellows 11 and the height H2 of the further bellows 12. Likewise - as in the previously described embodiments - the filtration area of ​​the further bellows 12 can be larger are designed as the filtration surface of the first bellows 11. This is particularly advantageous if the further bellows 12 forms a particle filtration layer.

<figref idref="f0006"><u>Fig. 5</u></figref> shows a detail from a top view of a filter element 100. In this top view only the further bellows 12 can be seen, but not the first bellows 11. The first bellows 11 lies below the further bellows 12. On the two side surfaces of the first bellows 11 and further Edge bands 8 are attached to the bellows 12, for example glued to the bellows 11, 12. The edge bands 8 have two functions: firstly, the bellows 11, 12 are stabilized and, secondly, possible bypasses between the bellows 11, 12 and a surrounding filter holder 20, for example a filter frame or a filter housing, are closed. This in<figref idref="f0003">Figure 2b</figref> The engagement element 9 shown can be connected to an edge band 8 in a materially bonded manner. It is in<figref idref="f0006">Fig. 5</figref> however, it cannot be seen either, since it is located between the first bellows 11 and the further bellows 12 and thus below the visible further bellows 12.

List of reference symbols

<dl id="dl0002" compact="compact"><dt>1</dt><dd>Filter medium</dd><dt>2</dt><dd>Folding edge</dd><dt>3</dt><dd>Folding surface</dd><dt>4</dt><dd>Fold Mountain</dd><dt>5</dt><dd>Faltental</dd><dt>6</dt><dd>Fold height</dd><dt>7</dt><dd>-</dd><dt>8</dt><dd>Edge band</dd><dt>9</dt><dd>Engagement element</dd></dl><dl id="dl0003" compact="compact"><dt>11</dt><dd>first bellows</dd><dt>12</dt><dd>another bellows</dd></dl><dl id="dl0004" compact="compact"><dt>20</dt><dd>Filter mount</dd></dl><dl id="dl0005" compact="compact"><dt>100</dt><dd>Filter element</dd></dl><dl id="dl0006" compact="compact"><dt>h1</dt><dd>Height of first bellows</dd><dt>h2</dt><dd>Height of additional bellows</dd></dl><dl id="dl0007" compact="compact"><dt>L.</dt><dd>Fluid flow (air flow)</dd></dl><dl id="dl0008" compact="compact"><dt>O</dt><dd>Upper edge of 1st bellows</dd><dt>U</dt><dd>Lower edge of further bellows</dd></dl>