CN106963286B

CN106963286B - Air filter that can be backwashed and vacuum cleaner comprising such an air filter

Info

Publication number: CN106963286B
Application number: CN201611186069.3A
Authority: CN
Inventors: M.塞尔内基; B.萨利斯; M.科内利森
Original assignee: Vorwerk and Co Interholding GmbH
Current assignee: Vorwerk and Co Interholding GmbH
Priority date: 2015-12-21
Filing date: 2016-12-20
Publication date: 2021-12-14
Anticipated expiration: 2036-12-20
Also published as: CN106889948A; TW201729743A; DE102016118807A1; DE102016118806A1; IT201600127010A1; TW201726042A; IT201600126901A1; CN106963286A

Abstract

The invention relates to a backflushable air filter (1) for installation in a vacuum cleaner (2). In order to achieve an optimum regeneration of the air filter (1), it is proposed that the air filter (1) has a filter interior (4) bounded by a filter wall (5) for receiving dust. The invention further relates to a vacuum cleaner (2) having a backwashable air filter (1).

Description

Air filter that can be backwashed and vacuum cleaner comprising such an air filter

Technical Field

The invention relates to a backflushable air filter for installation in a vacuum cleaner.

The invention further relates to a vacuum cleaner having a backflushable air filter, and to a vacuum cleaner having a dust chamber, a fan and a backflushable air filter, wherein the air filter separates the dust chamber from a clean air chamber, wherein the air filter is traversed by air to be cleaned during operation of the filter from the direction of the dust chamber in the direction of the clean air chamber, and wherein the air filter is traversed by flushing air during regeneration operation from the direction of the clean air chamber in the direction of the dust chamber.

Technical Field

Backflushable air filters and vacuum cleaners having backflushable air filters are known from the prior art. Backwashable air filters are also commonly referred to as permanent filters. The air filter can remain inside the vacuum cleaner for a substantially long period of operation and can remove dust deposits during regeneration operation, so that it can be used again later for the filter operation.

In connection with a vacuum cleaner, these air filters are used in order to protect the fan of the vacuum cleaner from dust, i.e. preferably dust and dirt. The air filter is occupied continuously on a regular basis during operation of the filter of the vacuum cleaner, so that a back flushing of the air filter is required as the operating time of the vacuum cleaner increases in order to maintain the desired cleaning effect of the vacuum cleaner.

EP 2979602 a1 discloses a vacuum cleaner, for example designed as a handheld battery suction device, which has a backwashable air filter. During operation of the filter of the vacuum cleaner, the air to be cleaned flows from the outside through its circumferential surface to the air filter which can be backwashed. From the backflushable air filter, the dust-cleaned air enters the interior of the air filter and reaches the fan of the vacuum cleaner. Dust is retained on the circumferential surface of the air filter inside the dust chamber of the cleaner. For regenerative operation, for example, the vacuum cleaner is connected, for example, together with its suction nozzle, to a second vacuum cleaner, which sucks in dust or dirt. The backflushable air filter is thereby flushed by the air flow in the opposite direction, i.e. from the inside to the outside, so that dust deposited on the circumferential surface of the filter can be separated and can be transferred to the second vacuum cleaner together with other dust contained in the dust chamber.

In order to guide dust out of the circumferential surface of the air filter during regeneration operation, it is necessary to provide a sufficiently large gap between the wall of the dust chamber and the circumferential surface of the air filter, and therefore there is no narrow portion in the gap where, for example, coarse impurities may be caught.

Disclosure of Invention

Based on the prior art described above, it is therefore an object of the present invention to provide a backwashable air filter and a vacuum cleaner having a backwashable air filter, in which the air filter can be optimally regenerated even if the installation space available inside the vacuum cleaner is small.

In order to solve the aforementioned problems, the invention proposes, firstly, a backflushable air filter for installation in a vacuum cleaner, which air filter has a filter interior bounded by a filter wall for accommodating dust.

According to the invention, the air filter now has a filter interior which provides a free volume and which is designed to receive dust during operation of the filter. The air filter is therefore suitable for being traversed from the inside to the outside during operation of the filter and for being supplied with flushing air from the outside to the inside during regeneration operation. The filter interior of the air filter is delimited by its own filter wall, preferably by the filter active material of the air filter. To form the filter interior space, the air filter has at least one shape extending out of a plane for forming a volume for containing dust. Since the filter interior of the backwashable air filter thus forms a partial region of the dust chamber of the vacuum cleaner itself, the dust is located only on the inner side of the air filter or on the wall inside the dust chamber, so that no dust sticks to the outside of the air filter, for example on its circumferential surface, and therefore no narrow regions are present in which coarse impurities can get stuck. The periphery of the air filter, i.e. its circumferential surface, is completely part of the clean air chamber, so that the gap between the air filter and the wall of the dust chamber accommodating the air filter only has to meet a small requirement for a minimum flow cross section.

It is also proposed that the filter interior in the region of the cross-section of the air filter intersecting the filter wall can adjoin the dust compartment of the vacuum cleaner without obstruction. The filter interior of the air filter therefore has a preferred connection region which can be connected without flow obstacles or the like to a dust chamber of the vacuum cleaner. Advantageously, the filter interior adjoins the dust chamber here via an open cross section oriented perpendicularly to the longitudinal extent of the air filter. The longitudinal extent of the air filter can be particularly advantageously the main flow direction through the air filter also during regeneration operation. The connection of the wall of the filter interior of the air filter to the dust compartment of the vacuum cleaner in a shape corresponding thereto is also advantageously achieved by the unobstructed connection possibility.

It is particularly proposed that the filter wall is free of undercuts in the main flow direction through the air filter. This enables a simplified regeneration of the filter interior, since dust accumulating on the filter wall of the filter interior can be discharged from the filter interior of the air filter in the main flow direction without obstruction from the interior during regeneration operation, without the dust remaining on the undercuts of the air filter. Such undercuts can be, for example, an inwardly projecting projection on the filter wall of the filter interior or a shape of the filter interior which tapers in the main flow direction during regeneration operation, for example an air filter cross section which decreases in the main flow direction during regeneration operation.

Furthermore, it is proposed that the air filter be of cylindrical or truncated-cone design, wherein the main flow direction through the air filter runs parallel to the longitudinal axis of the cylinder or truncated cone. The volume of the cylinder or truncated cone forms part of the filter interior or dust chamber of the vacuum cleaner. The outer circumferential surface of the cylinder or of the truncated cone forms a circumferential surface through which the air flows in the partial region of the air filter. The inner volume of the air filter for receiving dust is advantageously obtained by this embodiment. Furthermore, the air filter is designed symmetrically with respect to its longitudinal axis, so that the air flow can flow uniformly to the circumferential surface of the air filter and the size of the flow area of the air flow can be varied slightly. The base of the cylinder or the truncated cone forms a cross section of the air filter intersecting the filter wall, which can be connected to the dust chamber of the vacuum cleaner without any hindrance, as long as the connecting region of the dust chamber of the vacuum cleaner has a larger cross section than the base of the cylinder or the truncated cone and the cross sections are respectively shaped in a manner corresponding to each other, for example, circular, so that no intersection occurs in a plane perpendicular to the longitudinal axis of the cylinder or the truncated cone.

It is proposed that at least one circumferential partial region of the filter wall has a filter active material. The filter active material may be preferably a filter nonwoven fabric which can filter fine dust out of the inhaled air. The filter material forms at least one peripheral partial region of the filter wall or preferably also the entire filter wall, so that when the filter is in operation, as large a filter effective area as possible is present.

Furthermore, it is proposed that an additional coarse filter be arranged in the filter interior. The coarse filter can be assigned in particular to the filter active material of the air filter. Coarse impurity filters prevent dust from becoming clamped on the inside of the filter wall, in particular in the folds or pores of the filter active material. In particular, in the case of folded filter active materials, it can also occur that in particular coarse impurities become trapped inside the filter active material, which, on the one hand, significantly reduces the filter effect of the air filter during operation of the filter and, on the other hand, impairs the regeneration operation. The coarse impurity filter retains coarse impurities flowing into the inner space of the filter, so that the coarse impurities cannot reach the filter wall at all. The coarse filter can be arranged either at a small distance from the filter active material, for example a few millimeters or centimeters, or also in the region of the air filter for connection to the dust chamber of the vacuum cleaner, so that coarse impurities do not reach the filter interior at all. The mesh size of the coarse impurity filter, e.g. a grid or mesh, is for example from half a millimetre to a few millimetres.

It is particularly proposed that the coarse impurity filter be arranged at a distance of at most 5mm from the filter active material. In this embodiment, the filter interior space within the air filter serves both for the accommodation of fine impurities and for the accommodation of coarse impurities, wherein the coarse impurities are close to the filter wall but remote from the filter active material, so that the coarse impurities are not embedded in the filter active material and the flow path remains open both during filter operation and during regeneration operation.

In addition to the above-described backwashable air filter, a vacuum cleaner having a backwashable air filter with one or more of the above-described features is also proposed by the invention. Correspondingly, the features described in connection with the air filter also apply to a vacuum cleaner with an air filter.

Furthermore, a vacuum cleaner is also proposed, having a dust chamber, a fan and a backwashable air filter, in particular of the type described above, wherein the air filter separates the dust chamber from a clean air chamber, wherein the air filter is traversed by air to be cleaned during operation of the filter from the direction of the dust chamber in the direction of the clean air chamber, and wherein the air filter is traversed by flushing air during regeneration operation from the direction of the clean air chamber in the direction of the dust chamber, wherein the air filter forms at least one partial volume of the dust chamber which contains dust.

According to the invention, the air filter itself is part of a dust chamber of the vacuum cleaner for receiving dust. The air filter here forms either only a part of the volume of the dust chamber or the entire dust chamber. As a result, dust (in contrast to the prior art) no longer deposits on the outside of the air filter but on the inside of the air filter, wherein the distance between the air filter and the clean air chamber wall required for optimum regeneration of the air filter can be reduced. The overall installation space of the vacuum cleaner can thus also be reduced. In particular, no coarse impurities are embedded on the outside of the filter wall during regeneration operation. But the dust collected in the air filter leaves the air filter from the inside.

It is furthermore proposed that the filter interior of the air filter has a capacity of at least 100 ml and at most 500 ml. The capacity of the air filter and the capacity of the further volume part region of the dust chamber of the vacuum cleaner are advantageously added here, so that, for example, in the case of a total capacity of 1000 ml of the vacuum cleaner, 500 ml can be provided by the filter interior of the air filter and 500 ml can be provided by the further volume part region of the dust chamber which is designed adjacent to the air filter.

Although the invention is particularly advantageous here for handheld battery suction devices, in which the maximum installation space of the vacuum cleaner is not to be exceeded, it can also be used in other vacuum cleaners and/or in combined suction-brushing devices. Furthermore, the invention can be used both on hand-held vacuum cleaners and also on automatically moving vacuum cleaners, in particular cleaning robots.

Drawings

The invention is further illustrated below with reference to examples. In the drawings:

figure 1 shows a perspective view of the cleaner from the outside;

fig. 2 shows the vacuum cleaner with the filter in operation, with the partial regions shown in longitudinal section;

FIG. 3 shows a partial region of the vacuum cleaner according to FIG. 2 in regeneration mode;

FIG. 4 shows a longitudinal section of an air filter;

fig. 5 shows a partial region of a vacuum cleaner according to another embodiment;

FIG. 6 shows a partial region according to FIG. 5 during regeneration operation;

fig. 7 shows a plan view of a part of the region according to fig. 6.

Detailed Description

Fig. 1 shows a vacuum cleaner 2, which is designed here as a handheld battery vacuum cleaner. The vacuum cleaner has a housing with a handle 13, by means of which handle 13 a user can hold the vacuum cleaner 2 in his hand and can guide the vacuum cleaner 2. A switch 12 is provided on the handle 13, and the switch 12 is used to turn on and off the motor 11. The motor 11 drives the fan 8 of the cleaner 2. A suction nozzle 10 is also provided on the housing of the vacuum cleaner 2, through which suction nozzle 10 dust and air can be sucked into the vacuum cleaner 2 by means of the fan 8. The vacuum cleaner 2 also has a dust chamber 3 with an air filter 1, which air filter 1 is a regenerable permanent filter. The air filter 1 separates a dust chamber 3 of the cleaner 2 from a clean air chamber 9. The filter interior 4 of the air filter 1 simultaneously forms part of the dust compartment 3 of the vacuum cleaner 2.

During operation of a filter of a generic vacuum cleaner 2, the fan 8 sucks air and dust through a suction nozzle 10 formed on the housing into the dust chamber 3 of the vacuum cleaner 2 and thus also into the filter interior 4 of the air filter 1. The sucked-in dust remains in the filter interior 4 of the air filter 1 or in the dust chamber 3, while only purified air can pass through the filter wall 5 of the air filter 1, i.e. through the filter active material 6 arranged thereon, into the clean air chamber 9 and to the fan 8.

During operation of the filter, dust is continuously deposited on the filter active material 6 of the filter wall 5, so that from time to time a regeneration of the air filter 1 is necessary in order to maintain the desired suction power of the vacuum cleaner 2. In regeneration mode, the fan 8 of the vacuum cleaner 2 is then operated, for example, in the reverse direction, so that from the fan 8, flushing air is blown from the outside through the filter active material of the air filter 1 into the filter interior 4 and the entire dust compartment 3 of the vacuum cleaner 2 and from the dust compartment 3 further to the suction nozzle 10. This enables the filter wall 5, the air filter 1 and the entire dust compartment 3 of the vacuum cleaner 2 to be cleaned.

Fig. 2 shows the vacuum cleaner 2 in a partially cut-away state. The filter operation of the vacuum cleaner 2 is shown here. The illustrated air filter 1 is designed here as a cylinder, wherein the filter wall 5 has the filter active material 6 and forms the circumferential surface of the air filter 1. The air filter 1 separates a dust chamber 3 from a clean air chamber 9, which dust chamber 3 is also partly formed by the filter interior space 4 of the air filter 1. The dust chamber 3 also has a partial region arranged outside the air filter 1. The dust chamber 3 has a cross section of the same size both inside the air filter 1 and outside the air filter 1, i.e. the dust chamber 3 here forms a cylinder with a cross section that is constant over the entire longitudinal dimension. The dust compartment 3 has a closure element 14, which closure element 14 is designed here as a cover element and is deflected into the dust compartment 3 when the filter shown is in operation as a result of the low pressure generated by the fan 8, so that air and dust can enter the dust compartment 3 on the basis of the suction nozzle 10.

During operation of the filter shown in fig. 2, the vacuum cleaner 2 is traversed by an air flow, the flow direction of which is indicated by an arrow in the drawing. First, dust-laden air enters the vacuum cleaner 2 through the suction nozzle 10 and enters the dust chamber 3 and the filter interior 4 of the air filter 1 through the open closure element 14. In this case, dust accumulates on the filter active material 6 of the filter wall 5 of the air filter 1. Only dust-cleaned air flows from the filter interior 4 through the filter active material 6 of the filter wall 5 into the clean air chamber 9 of the vacuum cleaner 2. The air then passes from the clean air chamber 9 and finally to the fan 8 of the cleaner 2.

Fig. 3 shows a subregion of the vacuum cleaner 2 already shown in fig. 2 during regeneration operation. The vacuum cleaner 2 is preferably connected to a collecting container (not shown), for example a base station or another vacuum cleaner, by means of its suction nozzle 10. In regeneration operation, the flushing air flows through the cleaner 2 in the opposite direction to the filter operation, as is indicated by the arrows in the figure. The air flow for the regeneration operation can be generated either by the fan 8 of the vacuum cleaner 2 itself or by means of an external vacuum cleaner fan or a base station connected to the vacuum cleaner 2. The flushing air flows from the inside of the clean air chamber 9 to the air filter 1, wherein the flushing air is applied from the outside to the inside to the filter wall 5 of the air filter 1. The flushing air passes through the filter active material 6 and enters the filter interior 4 of the air filter 1. In this case, the dust collected from the interior on the filter wall 5 is removed and, together with other dust collected in the filter interior 4 or the dust compartment 3, is discharged in the direction of the suction nozzle 10 of the vacuum cleaner 2 via the open closure element 14.

Fig. 4 finally shows an air filter 1 according to a particular embodiment. In this embodiment, the air filter 1 has a coarse filter 7 in the filter interior 4, which coarse filter 7 is arranged here substantially parallel to the filter active material 6 of the filter wall 5, so that air flowing into the filter interior 4 first has to pass through the coarse filter 7 in order to reach the filter active material 6. The coarse impurity filter 7 has a larger mesh size than the filter active material 6 of the filter wall 5. The coarse impurity filter 7 has a mesh size of, for example, 3 mm. This mesh size is suitable for filtering coarse impurities, such as plant parts, stones and dust, with a size of more than 3 mm, so that only fine impurities, i.e. air of fine dust, below the mesh size of the coarse impurity filter 7 can reach the filter active material 6 of the air filter 1. This prevents coarse impurities from being trapped inside the filter active material 6 of the filter wall 5. In the regeneration mode, coarse impurities collected on the coarse impurity filter 7 are discharged from the dust chamber 3 of the air filter 1 or the vacuum cleaner 2 in the opposite direction to the filter mode.

Fig. 5 to 7 show further embodiments of a vacuum cleaner 2 with a backwashable air filter 1. The figures show longitudinal sections of a partial region of the vacuum cleaner 2 with the dust chamber 3 without (fig. 5) or with (fig. 6) a base station 15 connected to the dust chamber 3.

An air filter 1 is arranged in the dust chamber 3, wherein the air filter 1 is designed here as a three-dimensional air filter 1. The air filter 1 has a filter wall with a filter active material 6 for filtering dust-laden air during suction operation of the vacuum cleaner 3. The air filter 1 widens in the direction of an emptying opening 16 of the dust chamber 3, wherein a straight line connecting the air filter 1 with the emptying opening 16 defines the direction 3 of emptying the dust chamber.

The air filter 1 has a plurality of

possible cross sections

17, 18 in the emptying direction, wherein, in particular, a cross section 17 at a smaller end face of the air filter 1 and a cross section 18 at a larger end face of the air filter 1 are of interest for the invention. The air filter 1 is here, for example, a fine impurity filter, wherein an additional coarse impurity filter can also be provided in combination, which is arranged upstream of the air filter 1 in the direction from the emptying opening 16 to the fan 8. The coarse filter can be designed, for example, as a flat filter.

The dust chamber 3 is designed such that the air filter 1 widens, viewed in the emptying direction, and the dust chamber 3 has only a cross section of constant size from the larger cross section 18 of the air filter 1 up to the emptying opening 16. The dust chamber 3 can additionally also widen from the cross section 18 to the emptying opening 16.

According to fig. 6, the collecting chamber 19 of the base station 15 is connected to the emptying opening 16 during regeneration of the dust chamber 3. The cross section 20 of the emptying opening 16 is smaller than the collecting chamber opening 21. In regeneration mode, the vacuum cleaner 2 is arranged above the base station 15 parallel to the force of gravity acting on the dust. For this purpose, the vacuum cleaner 3 and the base station are configured in accordance with one another such that the vacuum cleaner 3 for a defined regeneration operation can only be fixed in the base station 15 such that the emptying direction is oriented parallel to the force of gravity. Thus, also the air filter 1 and the emptying opening 16 are superimposed in the embodiment shown here.

Fig. 7 shows a plan view of the dust chamber starting from the plane of the cross section 17 of the air filter 1 shown in fig. 6. Viewed in the emptying direction, the circumferential line of the

cross sections

17, 18 of the air filter 1 and the cross section 20 of the emptying opening 16 are arranged concentrically with respect to one another. The

cross sections

17, 18, 20 in this case each have the geometry of a circle, so that the boundary lines describe a circle having different diameters. The circumferential line with the smallest diameter corresponds here to the cross section 17 of the smaller end face of the air filter 1. The closest circumferential line radially outward corresponds to the cross section 18 of the larger end face of the air filter 1. The boundary line with the largest diameter finally belongs to the cross section 20 of the emptying opening 16. The circle-shaped (and concentric arrangement) of the circumferential lines 5 and the

cross sections

17, 18, 20 which increase in the emptying direction do not coincide, viewed in the emptying direction. In this way, no undercuts are present in the emptying direction, i.e. a deposition surface (on which dust can be deposited) inside the dust chamber 3.

The invention is based on the idea that during a suction operation of the vacuum cleaner 2, dust is initially conveyed from the surface to be cleaned into the dust chamber 3 by means of the fan 8 of the vacuum cleaner 2. In this case, dust is deposited both on the air filter 1, in particular the filter active material 6, and in the remaining region of the dust chamber 3. For regeneration of the dust compartment 3, the user of the vacuum cleaner 25 connects the vacuum cleaner 2 to the base station 15, wherein the emptying opening 16 of the dust compartment 3 is connected with the collecting compartment opening 21 of the collecting compartment 19. For this purpose, the suction nozzles arranged on the dust chamber 3 are previously removed if necessary.

In the regeneration mode, the fan 8 of the vacuum cleaner 2 is operated in the opposite direction to the flow direction for the suction mode, so that the fan 8 draws an air flow through the air filter 1 into the dust chamber 3 and conveys the deposited dust in the direction of the base station 15. In regenerative operation, the operating power of the fan 8 is here, for example, 400 watts, which is higher than the power of the fan 8 in suction operation (for example 300 watts).

The air flow generated by the fan 8 impinges on the air filter 1 on the side facing the fan 8 opposite the filter active material 6. The air flow flows through the material of the air filter 1 and separates dust that accumulates on the filter active material 6, which dust thus moves further into the dust chamber 3 in the emptying direction and thus in the direction of the emptying opening 16 and in the direction of the collection chamber 19 of the base station 15. Whereby the dust chamber 3 can be optimally regenerated.

Although the invention is shown here, for example, with only the air filter 1 and the emptying opening 16 being arranged in a defined manner inside the dust compartment 3 and with only the

circular cross sections

17, 18, 20 of the air filter 1 and the emptying opening 16, the vacuum cleaner 2, in particular the dust compartment 3, can also be designed in another way. The cross-sections 17, 18, 20 may differ in, for example, geometry and size. It is also possible for the circumferential limits of the

cross sections

17, 18, 20 to coincide, viewed in the emptying direction, wherein the

first cross section

17, 18, 20 in the emptying direction projects by no more than 5mm beyond the

downstream cross section

17, 18, 20. The air filter 1 and/or the dust compartment 3 can also be reduced in size, for example, in the emptying direction. It is only important here that no significant accumulation surface for dust is present during regeneration operation within the scope of the invention, so that an optimum emptying of the dust chamber 3 is ensured.

Furthermore, embodiments are also conceivable in which the emptying direction is not parallel to the gravitational direction or the arrangement of the air filter 1 and the emptying opening 16 is not parallel to the longitudinal extent of the dust chamber 3, but is offset from one another by an angle different from 0 degrees, for example, so that the surface normals of the

cross sections

17, 18, 20 intersect.

The regeneration operation can also be varied with respect to the fan 8 used. As an alternative to the own fan 8 of the vacuum cleaner 2, a fan, for example of the base station 15, can be used for regeneration. Furthermore, as an alternative to blowing out from the dust chamber 3, dust can also be sucked out of the dust chamber 3.

List of reference numerals

1 air filter

2 dust collector

3 dust chamber

4 filter inner space

5 wall of filter

6 Filter active Material

7 coarse impurity filter

8 Fan

9 clean air chamber

10 suction nozzle

11 Motor

12 switch

13 handle

14 closure element

15 base station

16 emptying opening

17 cross section

18 cross section

19 collecting chamber

20 cross section

21 collection chamber opening

Claims

1. A backflushable air filter (1) for installation in a vacuum cleaner (2), wherein the air filter (1) has a filter interior (4) bounded by a filter wall (5) for accommodating dust, wherein the air filter (1) has a cross section (18) corresponding to an end face, through which cross section (18) dust and air flow into the air filter (1) during filter operation, wherein the air filter (1) is traversed by the inflowing air from the inside to the outside, characterized in that the air filter (1) is acted upon with flushing air from the outside to the inside during regeneration operation, wherein the flushing air flowing into the air filter (1) and the dust sucked into the filter interior (4) leave the air filter (1) through the cross section (18) corresponding to the end face, and wherein the air filter (1) is designed cylindrically or frustoconically, wherein the main flow direction through the air filter (1) extends parallel to the longitudinal axis of the cylinder or frustum during regeneration operation, and wherein a cross section (18) of the air filter (1) forms the entire end face of the filter interior (4) of the air filter (1), such that the dust can leave the filter interior (4) through the entire end face of the filter interior (4).

2. A backflushable air filter (1) as claimed in claim 1, wherein the filter interior (4) can adjoin the dust chamber (3) of the vacuum cleaner (2) in the region of a cross section of the air filter (1) intersecting the filter wall (5) without obstruction.

3. A backflushable air filter (1) according to claim 1 or 2, characterized in that the filter wall (5) is free of undercuts in the main flow direction through the air filter (1).

4. A backflushable air filter (1) as claimed in claim 1, wherein at least one circumferential partial region of the filter wall (5) has filter active material (6).

5. A backflushable air filter (1) according to claim 1, characterized in that an additional coarse-impurity filter (7) is arranged in the filter interior (4).

6. A backflushable air filter (1) as claimed in claim 5, characterized in that the coarse filter (7) is assigned to the filter active material (6) of the air filter (1).

7. A backflushable air filter (1) as claimed in claim 5, wherein the coarse impurity filter (7) is arranged at a distance of up to 5mm from the filter active material (6).

8. A vacuum cleaner (2) having a backwashable air filter (1) as claimed in any one of claims 1 to 7.