DE102024203003A1 - Separation unit for a suction device with a flap - Google Patents

Abstract

A separation unit (113) for a suction device (100) is described. The separation unit (113) comprises a collecting container enclosed by a housing wall (227), and a filter unit (225) arranged in the collecting container, which filter unit is designed to retain dirt particles from a suction air stream (212) on the surface of the filter unit (225). The collecting container has an inlet opening (211) arranged on the housing wall (227), which is closed by a flap (200), wherein the flap (200) has a total area (300) for covering the inlet opening (211), and wherein the flap (200) is fastened to the housing wall (227) at a main edge (301) of the total area (300). The flap (200) has a linear predetermined bending point (202) that allows a partial area (305) of the total surface (300) facing away from the main edge (301) to be bent about an additional bending axis. The flap (200) is designed such that the partial area (305) of the total surface (300) of the flap (200) is bent away from the housing wall (227) by a force acting on the flap (200) from the outside, thereby exposing a partial area of the inlet opening (225) corresponding to the partial area (305) of the total surface (300).

Description

The invention relates to a separation unit for a suction device, in particular for a cordless and/or hand-held vacuum cleaner.

A suction device, in particular a handheld vacuum cleaner, typically comprises a suction unit that can be carried and guided by a user by hand. The suction unit has a fan that is operated with electrical energy from an electrical energy storage device of the suction unit. The fan is designed to generate a suction air flow in order to suck contaminants through the suction mouth of the suction unit into the separation unit of the suction unit, wherein the separation unit has a collection container for contaminants. To increase the suction power of the suction unit, the suction air flow is preferably introduced into the separation unit and/or guided within the separation unit in such a way that the suction air flow flows in a cyclone-like manner around the central filter unit of the separation unit.

This document deals with the technical task of further optimising the inflow of the suction air flow into the separation unit of a suction device, in particular to improve the absorption of coarse dirt and/or the suction power.

The object is achieved by the subject matter of the independent patent claim. Advantageous embodiments are defined in particular in the dependent patent claims, described in the following description, or illustrated in the accompanying drawings.

According to one aspect, a separation unit for a suction device is described. The separation unit comprises a collecting container enclosed by a housing wall. The separation unit can have a longitudinal axis, and the housing wall of the collecting container can be (circularly) cylindrically shaped around the longitudinal axis. The housing wall can, for example, correspond to the outer surface of a hollow cylinder. The collecting container also has an inlet opening arranged on the housing wall, which is closed with a (flexible) flap. The inlet opening is preferably arranged on the top side of the collecting container (which is intended to be oriented upwards during operation).

The separation unit may further comprise a filter unit arranged in the collection container, which is designed to retain dirt particles from a suction air stream (entering the collection container through the inlet opening) on the surface of the filter unit. The separation unit is preferably designed such that the suction air stream entering the collection container through the inlet opening flows in a cyclone-like manner around the filter unit. For this purpose, the separation unit may be designed such that the suction air stream entering the collection container through the inlet opening has a flow direction that runs essentially in the circumferential direction around the longitudinal axis.

The flap at the inlet opening can have a total surface area for (completely) covering the inlet opening. Furthermore, the flap can be attached to the housing wall at a main edge of the total surface area. The main edge can be aligned parallel to the longitudinal axis.

The flap has a linear predetermined bending point, which enables a bending of a portion of the total surface of the flap facing away from the main edge about an additional bending axis. The predetermined bending point is spaced from the main edge of the total surface. Furthermore, the predetermined bending point (and the associated additional bending axis) can divide the total surface of the flap into the partial region and a complementary remainder. The predetermined bending point can be configured such that the partial region can be bent (in particular twisted) about the additional bending axis relative to the rest of the total surface.

The predetermined bending point can be implemented as a local (linear) thinning and/or by a locally modified material of the flap. In particular, the flap can have a thinner and/or different material locally along the additional bending axis (compared to the areas of the total surface without the predetermined bending point). The linear predetermined bending point can be designed, in particular, as a film hinge, especially when the flap is made of a plastic, especially a flexible plastic.

The predetermined bending point can be implemented by a local (linear) profiling of the flap, in particular the surface of the flap. The profiling can be arranged on the outer side of the flap (facing away from the collection container) and/or on the inner side of the flap (facing the collection container). This allows a predetermined bending point to be provided in a particularly flexible and efficient manner.

The flap is designed in such a way that the partial area of the total surface of the flap is bent away from the housing wall (into the collecting container) by a force acting on the flap from the outside (in the radial direction) and thereby releases a portion of the inlet opening corresponding to the portion of the total area. The flap can, in particular, be designed such that the portion of the total area of the flap is bent away from the housing wall and into the collection container by the suction air flow acting on the flap from the outside and/or by a (relatively large) dirt particle carried along by the suction air flow.

By providing a dust retention flap on the collection container of a separation unit, which has one or more additional predetermined bending points, the quality of the separation unit can be increased in an efficient and reliable manner with regard to the absorption of coarse dirt and with regard to the optimized alignment of the flow direction of the suction air flow (to increase the suction power).

The flap can have several linear predetermined bending points, each of which allows a portion of the total surface facing away from the main edge to bend around an additional bending axis. The different predetermined bending points can each have a different distance from the main edge. For example, several predetermined bending points arranged parallel to the main edge can be provided at different distances from the main edge. By using a flap with several predetermined bending points, the ability to absorb dirt particles of different sizes can be further improved.

The flap can have two linear target bending points, each with an additional bending axis. The additional bending axes are aligned differently from each other and may intersect (on the flap). This allows for particularly precise alignment of one or more sub-areas of the overall surface to further optimize the flow direction of the suction air stream.

The flap can have a main bending point (directly) on the main edge, which allows the entire surface to bend around a main bending axis. The main bending axis can run parallel to the longitudinal axis. Furthermore, the additional bending axis can run parallel to the main bending axis. This allows the separation unit to be optimized for the collection of dirt particles of different sizes.

Alternatively, the additional bending axis can be inclined to the main bending axis, particularly at an angle between 10° and 45° to the main bending axis. By using a target bending point with an inclined additional bending axis, the flow direction of the suction air stream can be further optimized.

The additional bending axis can, for example, be aligned with respect to the longitudinal axis in such a way that the portion of the total surface of the flap bent around the additional bending axis creates an impulse on the suction air flow in the direction of the longitudinal axis. For this purpose, the additional bending axis can be aligned obliquely to the longitudinal axis, in particular at an angle of 5° or more to the longitudinal axis. In this way, a suction air flow can be efficiently created within the collection container, which flows helically around the filter unit and towards one end of the collection container, so that the dirt particles from the suction air flow are concentrated at the end of the collection container. In this way, the service life of the separation unit (between emptying processes) can be increased efficiently and reliably.

The flap can be designed such that the bending of the partial area around the additional bending axis has a larger bending angle than the bending of the entire area around the main bending axis, particularly when the volume flow of the suction air flow acting on the flap from the outside is equal to or less than a predefined volume flow threshold value (i.e., particularly when the suction air flow has a relatively small volume flow). This can achieve a particularly optimal flow direction of the suction air flow within the collection container.

According to a further aspect, a suction device, in particular a handheld vacuum cleaner, is described, which comprises the separation unit described in this document. The suction device further comprises a fan configured to generate a suction air flow from the suction mouth of the suction device, through the inlet opening of the separation unit, through the filter unit, and to the fan.

It should be noted that any aspects of the separation unit and the suction device described in this document can be combined in a variety of ways. In particular, the features of the patent claims can be combined in a variety of ways.

• 1 eine beispielhafte Saugvorrichtung mit einer Saugeinheit, einem Saugrohr und einer Düse;
• 2a bis 2c unterschiedliche Ansichten einer Saugeinheit und der Abscheideeinheit einer Saugeinheit;
• 3a bis 3b unterschiedliche Ansichten von flexiblen Klappen zur Abdeckung der Eingangsöffnung einer Abscheideeinheit; und
• 3c eine schematische Darstellung einer Klappe in einer Draufsicht und in einer Seitenansicht.

The invention will be described in more detail below with reference to exemplary embodiments illustrated in the accompanying drawings.

• 1 an exemplary suction device with a suction unit, a suction pipe and a nozzle;
• 2a to 2c different views of a suction unit and the separation unit of a suction unit;
• 3a to 3b different views of flexible flaps for covering the inlet opening of a separation unit; and
• 3c a schematic representation of a flap in a top view and a side view.

As stated at the beginning, this document is concerned with achieving a particularly advantageous inflow of the suction air stream into the separation unit of a suction device, in particular to ensure a permanently high suction power and reliable collection of coarse dirt. In this context, 1 an exemplary (handheld) vacuum cleaner 100 (as an example of a suction device) comprising a suction unit 110 with an electrical energy storage device 111. The suction unit 110 comprises a (hand) handle 112, which can be grasped by a user with one hand to hold the suction unit 110. The fan of the suction unit 110 creates a suction air flow through the suction mouth 114 of the suction unit 110, via the separation unit 113 of the suction unit 110, and up to the fan. The suction unit 110 can be designed to be used independently as a suction device.

An accessory 120, 130 can be connected to the suction unit 110 via a coupling 121. In the example shown, the suction unit 110 is connected via a coupling 121 to a suction pipe 120, which in turn is connected via a coupling 121 to a floor nozzle 130.

2a to 2c show different views of a suction unit 110 and a separation unit 113. The suction air flow 112 caused by the fan 230 is sucked through the suction mouth 114 of the suction unit 110 into the separation unit 113. The separation unit 113 has an outer housing wall 227 which encloses a filter unit 225. A collecting container is formed by the housing wall 227. The suction air flow 112 is sucked through an (inlet) opening 211 formed on the housing wall 227 into the collecting container enclosed by the housing wall 227. When introduced into the collecting container, the suction air flow 112 is preferably directed such that the suction air flow 112 circulates in a cyclone-like manner around the (circular-cylindrical) filter unit 225. The suction air stream 112 is further drawn through the surface of the filter unit 225 toward the central longitudinal axis 220 of the separation unit 113. The contaminants from the suction air stream 112 are retained on the surface of the filter unit 225 and remain in the collection area 226 formed between the filter unit 225 and the housing wall 227.

The (circular-cylindrical) collecting container formed by the housing wall 227 extends along the longitudinal axis 220 from a first end face 221 (facing the fan 230) to a second end face 222 (facing away from the fan 230). A lid 224 covering the collecting container can be arranged on the second end face 222. The lid 224 can be opened (e.g., folded open) so that contaminants from the collecting area 226 of the collecting container can be removed via the second end face 222.

An ejection and/or compression element 240 may be arranged within the collection container and is designed to be moved along the longitudinal axis 220. The ejection and/or compression element 240 may, as in 2b shown, be formed as a ring arranged around the filter unit 225. The ejection and/or compression element 240 can extend radially (relative to the longitudinal axis 220) from the surface of the filter unit 225 to the inside of the housing wall 227.

The ejection and/or compression element 240 can be arranged in a basic state on the first end face 221 of the collection container. Furthermore, the ejection and/or compression element 240 can be configured to be moved along the longitudinal axis 220 from the first end face 221 to the second end face 222, such that the contaminants arranged in the collection area 226 are pushed toward the second end face 222 by the ejection and/or compression element 240. This makes it possible to compress the contaminants arranged in the collection area 226 (in the region of the second end face 222) during operation of the suction unit 110, so that the surface of the filter unit 225 is substantially free of contaminants, thus continuing to provide a high suction power. Furthermore, the ejection and/or compression element 240 can conveniently push contaminants out of the collection container along the longitudinal axis 220 via the second end face 222 (and the opened lid 224) in order to empty the collection container.

Such as in 2b As shown, the housing wall 227 of the collecting container has a frame 210 that surrounds the opening 211 to the collecting area 226 of the collecting container. The frame 210 is preferably arranged in the immediate vicinity of the first end face 221 of the collecting container. Within the frame 210, a flexible flap 200 is arranged, which is designed such that the flap 200 closes the opening 211 bordered by the frame 210 when no suction air flow 212 is caused by the fan 230, ie when no forces act on the flap 200 in a radial direction from the outside into the collection container. The collection container can thus be closed by the flexible flap 200, so that it can be reliably prevented that contaminants can fall out of the collection container through the opening 211 (e.g., when the separation unit 113 is separated from the suction unit 110 in order to empty the separation unit 113).

The flap 200 can have a preload that presses the flap 200 toward the frame 210. This can ensure that the flap 200 is closed in a particularly reliable manner when no suction air flow 212 is generated.

The flap 200 is preferably made of a flexible material (e.g., a flexible plastic), so that the flap 200 is bent away from the frame 210 toward the filter unit 225 under the influence of a force acting on the flap 200 from the outside (caused, for example, by the suction air flow 212), thereby exposing at least part of the opening 211. This allows the suction air flow 212 to enter the collection container from the outside.

As from 2b As can be seen, the suction unit 110 can be designed such that the suction air flow 212, starting from the suction mouth 114, initially has a flow direction that is aligned substantially parallel to the longitudinal axis 220. At the inlet opening 211 and/or at the frame 210, the flow direction of the suction air flow 212 is deflected by approximately 90°, so that the suction air flow 212 flows in the circumferential direction (and thus substantially perpendicular to the longitudinal axis 220) through the inlet opening 211 into the collecting container.

During suction operation, the inlet opening 211 is preferably arranged (with respect to the circumferential direction) on the top side of the housing wall 227 of the collection container. This allows gravity to act on the contaminants in the suction air stream 212 to transport the contaminants into the collection container. On the other hand, due to the orientation of the inlet opening 211, it may happen that (particularly relatively large) dirt particles remain on the outside of the flap 200 and increasingly accumulate on the outside of the flap 200, possibly leading to a blockage of the inlet opening 211.

The dirt located on the outside of the flap 200 may fall off when the separation unit 113 is separated from the suction unit 110, which may be unpleasant for a user. Furthermore, if the inlet opening 211 becomes clogged, the suction operation must be interrupted, and the separation unit must be cleaned, which may also be unpleasant.

The flap 200 preferably has one or more predetermined bending points 201, 202 (as shown by way of example in the 3a to 3b shown), by means of which the opening angle of at least a partial region of the flap 200 can be increased. A predetermined bending point 201, 202 can be designed, in particular, as a (film) hinge. The flap 200 can have a main hinge 201 that runs along a (main) edge of the frame 210 and that enables opening of the entire flap 200 (i.e., the entire surface of the flap 200). Furthermore, the flap 200 has one or more (linear) predetermined bending points 202, each of which enables additional opening of a respective partial region of the flap 200.

The flap 200 can, as shown in the example 3c shown, have a total area 300, e.g., a rectangular total area, wherein the total area 300 completely covers the inlet opening 211. The total area 300 is delimited by a main edge 301 and one or more (in particular three) secondary edges 302. The main edge 301 is typically fixedly connected to the frame 210 of the inlet opening 211, so that the flap 200 cannot be moved away from the frame 210 at the main edge 301. The one or more secondary edges 302 are not connected to the frame 210 of the inlet opening 211 and can be moved away from the frame 210 (by the action of a radial force) to open the inlet opening 211.

A linear main bending point 201 (e.g., in the form of a film hinge) can be arranged on the main edge 301, which enables a rotational movement of the entire surface 300 of the flap 200 about the linear main bending point 201 (i.e., the main bending axis). The angle of rotation enabled by the main bending point 201 is typically limited (e.g., to 45° or less, or to 30° or less), so that the entire surface 300 of the flap 200 can only be opened up to a certain opening angle by the force of the suction air flow 212. This has the advantage that the flow direction of the suction air flow 121 through the inlet opening 211 has a particularly large directional component in the circumferential direction and only a relatively small directional component in the radial direction. a robust cyclone-like suction air flow 212 can be reliably achieved within the collection container of the separation unit 113.

On the other hand, the limitation of the opening angle of the main desired bending point 201 at the main edge 301 of the flap 200 can lead to relatively large dirt particles getting stuck on the outside of the flap 200.

The flap 200 can therefore have at least one further (linear) predetermined bending point 202, which enables additional rotation or bending of a partial area 305 of the total surface 300 of the flap 200 around the respective predetermined bending point 200 (i.e., around the respective bending axis). A further predetermined bending point 202 (in particular, a further film hinge) thus enables a partial area 305 of the total surface 300 (facing away from the main edge 301) to additionally move away from the frame 210 (in particular under the influence of a relatively large dirt particle). As a result, the inlet opening 211 can be opened further in the corresponding partial area of the inlet opening 211, so that even relatively large dirt particles can reach the collection container.

The additional bending or rotating away of a partial area 305 of the total surface 300 of the flap 200 is typically not caused by a suction air flow 212 that only has relatively small dirt particles. This further ensures that the flow direction of the suction air flow 212 has the largest possible directional component in the circumferential direction and only a relatively small directional component in the radial direction. On the other hand, the additional bending or rotating away of the partial area 305 of the total surface 300 of the flap 200 can be caused if a relatively large dirt particle, carried along by the suction air flow 212, acts on this partial area 305 of the total surface 300 (and thereby causes a relatively large force in the radial direction).

By additionally incorporating one or more film hinges 202, which are arranged transversely, longitudinally, diagonally, at the front and/or rear, or in various combinations on the elastic dust retention flap 200, it is thus possible for the flap 200 to open further in at least one or more partial areas 305 of the total area 300 when relatively large particles and/or a relatively large amount of dirt are present in the suction air flow 212, thus preventing dirt from becoming trapped between the flap 200 and the inlet opening 211 of the collection container. Furthermore, the wall orientation of the air flow 212 (toward the inside of the housing wall 227) is maintained for better dust separation. This wall orientation is achieved (at relatively high air volumes) by the main film hinge 201 (which, for example, runs along the longitudinal axis 220). At relatively lower air volumes, one or more subsequent longitudinally extending film hinges 202 can cause the flap 200 to open (at least one or more partial areas 305). Thus, even with a relatively low air volume, good wall orientation of the incoming suction air can be ensured.

The first end face 211 of the collection container of the separation unit 113 is typically oriented upwards during the suction operation of the suction unit 110, while the second end face 212 of the collection container is oriented downwards. Thus, during the suction operation, the contaminants (e.g., dust particles) arranged in the collection area 226 are subject to gravity, moving at least some of the contaminants toward the second end face 212. As a result, during the suction operation, fewer contaminants tend to be located near the first end face 211 than near the second end face 212. Therefore, to maintain the highest possible suction power, it is typically advantageous if the inlet opening 211 for the inlet of the suction air flow 212 into the collection container is arranged as close as possible to the first end face 211 of the collection container.

In order to keep the collection area 226 of the collection container of the separation unit 113 in the region of the inlet opening 211 as free as possible from contaminants, and thereby to provide a permanently high suction power, it is advantageous if the suction air flow 212 flows helically around the filter unit 225 and towards the second end face 212. For this purpose, the flap 200 on the inlet opening 211 can be designed to align the suction air flow 212 flowing through the inlet opening 211 such that the directional vector of the direction of movement of the suction air flow 212 has a first vector component in the circumferential direction and a second vector component in the longitudinal direction 220. The pitch of the helical flow direction of the suction air flow 212 can be defined by the ratio between the first vector component and the second vector component.

The flap 200 can have one or more (linear) desired bending points 202, which make it possible to bend or rotate one or more corresponding partial areas 305 of the total surface 300 of the flap 200 about a respective (bending) axis, wherein the respective (bending) axis runs obliquely with respect to the longitudinal axis 220. The normal vector perpendicular to the bending axis of a desired bending point 202 can in particular more particularly, have a directional component that is directed toward the second end face 222 of the collecting container. This can cause the suction air flow 212 to be directed toward the second end face 222 by the partial region 305 of the total surface 300 of the flap 200 that is bent around this bending axis, thereby creating a helical suction air flow 212 in the collecting container of the separation unit 113.

2b shows an exemplary flap 200 with a (linear) predetermined bending point 202, which defines a bending axis that is oriented obliquely to the longitudinal axis 220 such that the flow direction of the suction air stream 212 is directed (by a specific angle) toward the second end face 222 of the collecting container through the partial region 305 of the flap 200 bent around the bending axis. This can cause contaminants to accumulate more on the second end face 222 of the collecting container, and the inlet opening 211 remains free to receive additional contaminants. This can achieve a permanently high suction power.

The (dust) flap 200 at the inlet 211 of the collection container of the separation unit 113 can thus be designed such that the flap 200 can be opened depending on the air flow. The flap 200 can, in particular, have one or more further defined predetermined bending points 202 at its free end. The flap 200 can thus be designed to be inherently flexible.

The one or more profiles 202 (i.e., predetermined bending points) of the flap 200 can ensure that, with a relatively weak air flow 202, only an outer region of the inlet opening 211 is completely exposed by the flap 200, so that the air flow 202 flows reliably along the inside of the housing wall 227 of the collecting container into the collecting container (which is advantageous for the suction power of the suction unit 110). On the other hand, the one or more profiles 202 can ensure that relatively large particles can pass through the flap 200.

By using an obliquely arranged profiling 202 (ie desired bending point) of the flap 200, in addition to a flow of the suction air 202 in the circumferential direction around the filter unit 225, an additional swirl of the flow can be generated (as exemplified by the 2b shown dotted flow pattern), whereby the separation effect of the separation unit 113 can be further improved.

The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and figures are intended only to illustrate the principle of the separation unit 113 and/or the suction device 100.

List of reference symbols

100

Suction device (vacuum wiper)

110

suction unit

111

electrical energy storage

112

Handle

113

Separation unit

114

Suction mouth

120

Accessory (suction pipe)

121

coupling

130

nozzle

200

(Dust retention) flap

201

Main bending point (film hinge)

202

additional bending point (film hinge)

210

Frame

211

Inlet opening (collection container)

212

Suction air

220

Longitudinal axis

221

first front side (collection container)

221

second front side (collection container)

224

Lid

225

filter unit

226

Collection area

240

Ejection and/or compression element

300

Total area (flap)

301

Main edge

302

(free) edge

305

Partial area (of the total area)

Claims (12)

Separation unit (113) for a suction device (100); wherein - the separation unit (113) comprises a collecting container enclosed by a housing wall (227); - the collecting container has an inlet opening (211) arranged on the housing wall (227), which is closed by a flap (200); - the flap (200) has a total area (300) for covering the inlet opening (211); - the flap (200) is fastened to the housing wall (227) at a main edge (301) of the total surface (300); - the flap (200) has a linear predetermined bending point (202) which enables a bending of a partial area (305) of the total surface (300) facing away from the main edge (301) about an additional bending axis; and - the flap (200) is designed such that the partial area (305) of the total surface (300) of the flap (200) is bent away from the housing wall (227) by a force acting on the flap (200) from the outside, thereby exposing a partial area of the inlet opening (225) corresponding to the partial area (305) of the total surface (300). Separation unit (113) according to Claim 1 , wherein the flap (200) has a main desired bending point (202) on the main edge (301), by means of which a bending of the entire surface (300) about a main bending axis is enabled. Separation unit (113) according to Claim 2 , wherein the flap (200) is designed such that the bending of the partial area (305) about the additional bending axis has a greater bending angle than the bending of the entire surface (300) about the main bending axis when the volume flow of the suction air flow (212) acting from the outside on the flap (200) is equal to or less than a predefined volume flow threshold value. Separation unit (113) according to one of the Claims 2 until 3 , whereby the additional bending axis runs parallel to the main bending axis. Separation unit (113) according to one of the Claims 2 until 3 , wherein the additional bending axis runs obliquely to the main bending axis, in particular at an angle between 10° and 45° to the main bending axis. Separation unit (113) according to one of the preceding claims, wherein the flap (200) is designed such that the partial area (305) of the total surface (300) of the flap (200) is bent away from the housing wall (227) and into the collecting container by a suction air flow (212) acting on the flap (200) from the outside and/or by a dirt particle carried along by the suction air flow (212). Separation unit (113) according to one of the preceding claims, wherein - the flap (200) is made of a plastic, in particular a flexible plastic; and - the linear predetermined bending point (202) is designed as a film hinge. Separation unit (113) according to one of the preceding claims, wherein the flap (200) has a plurality of linear predetermined bending points (202), each of which enables a bending of a partial area (305) of the total surface (300) facing away from the main edge (301) about an additional bending axis. Separation unit (113) according to one of the preceding claims, wherein - the separation unit (113) comprises a filter unit (225) arranged in the collection container, which is designed to retain dirt particles from a suction air flow (212) on a surface of the filter unit (225); and/or - the separation unit (113) is designed such that the suction air flow (212) entering the collection container through the inlet opening (113) flows in a cyclone-like manner around the filter unit (225). Separation unit (113) according to one of the preceding claims, wherein - the separation unit (113) has a longitudinal axis (220); - the housing wall (227) of the collecting container is circularly cylindrical around the longitudinal axis (220); - the separation unit (113) is designed such that the suction air flow (212) entering the collecting container through the inlet opening (113) has a flow direction that runs substantially in the circumferential direction around the longitudinal axis (220); and - the additional bending axis is aligned with respect to the longitudinal axis (220) such that the partial region (305) of the total surface (300) of the flap (200) bent around the additional bending axis imparts an impulse to the suction air flow (212) in the direction of the longitudinal axis (220). Separation unit (113) according to Claim 10 , wherein the additional bending axis is aligned obliquely to the longitudinal axis (220), in particular at an angle of 5° or more to the longitudinal axis (220). Suction device (100) comprising, - a separation unit (113) configured according to one of the preceding claims; and - a fan (230) configured to cause a suction air flow (212) from a suction mouth (114), through the inlet opening (211) of the separation unit (113), through a filter unit (225), and to the fan (230).