Abstract: A filtering apparatus includes a housing having an inlet and at least an outlet, and a filter arrangement disposed in the housing, downstream of the inlet and upstream of the outlet for filtering a pressurized gas entering the housing through the inlet to provide a filtered pressurized gas at the outlet. The filter arrangement has first and second tubular filter elements. The first filter element is received within the second filter element. The filtering apparatus can be configured as a filter regulator when equipped with a pressure regulator. The filtering apparatus of filter regulator can be used with one or more spray guns or in a spraying system.

Abstract: A cyclone dirt separating apparatus and a vacuum cleaner having the same are disclosed. The cyclone dirt separating apparatus comprises a cyclone body including a first cyclone chamber in which dirt is separated preliminarily from air drawn in from an exterior by a centrifugal force; and a second cyclone chamber in which dirt is separated secondarily from the air discharged from the first cyclone chamber; and a dirt collecting case coupled to a lower end of the cyclone body for collecting the dirt. Also, the cyclone dirt separating apparatus further comprises a discharge guide duct passed through the cyclone body and the dirt collecting case and guiding the air discharged from the second cyclone chamber. Therefore, the air discharged through the discharge guide duct is directly entered to a motor mounting space of the vacuum cleaner.

Abstract: A vacuum cleaner includes a suction port assembly, a motor generating a suction force at the suction port assembly, and a cyclone dust collecting device for centrifugally separating air drawn in through the suction port assembly and the motor in sequence. The cyclone dust-collecting device includes an air discharge port penetratingly formed on an outer circumference of the cyclone dust-collecting device and exposed to an outside of the cleaner body, for guiding the air discharged to the outside. Accordingly, since the air discharge port is disposed in the cyclone dust collecting device, not in the cleaner body, a discharge channel for connecting the cyclone dust collecting device and cleaner body is omitted and thus a structure of the vacuum cleaner becomes simplified.

Abstract: A multi-cyclone dust separating apparatus includes: a multi-cyclone unit including a first cyclone chamber body having a first cyclone chamber and at least one protection chamber formed around at least a portion of an outer circumference of the first cyclone chamber, and at least one secondary cyclone chamber body disposed in the protection chamber, each secondary cyclone chamber body having at least one secondary cyclone chamber; a cover unit connecting an upper end of the multi-cyclone unit and guiding air discharged from the first cyclone chamber to the at least one secondary cyclone chamber; a dirt collecting unit adapted to connect to a lower end of the multi-cyclone unit and configured to collect dirt separated from the air in the first and secondary cyclone chambers; and an air discharge duct configured to discharge air that has passed through the multi-cyclone unit.

Abstract: A dust separating apparatus for a vacuum cleaner which is compact in configuration and is capable of preventing dirt from piling up on an entrance channel is provided. The dust separating apparatus includes a dust collecting receptacle adapted to collect dirt, and a cyclone unit eccentrically disposed in the dust collecting receptacle and adapted to whirl air drawn in through an inflow channel thereof, and the inflow channel may have an inclined upper surface which slopes downward toward a bottom of the dust collecting receptacle by a predetermined angle.

Abstract: A portable dust collection system for a wood shop or other dust producing environment is employed with a sander, power saw, router or other dust-producing tool such as a woodworking tool. A movable platform has a vertical intake pipe supporting a head portion formed with a shroud. A centrifugal impeller drives the intake air stream plus any entrained particles into one or more cyclonic separators, which deposit the dust in a respective drum supported on the platform beneath the cyclone. The air inlet from the tool enters the vertical pipe at a point partway up the pipe, so that large particles drop to the bottom end of the pipe, where a clean-out door is provided. The exhaust or discharge air from the cyclonic separator(s) passes out through a filter cartridge to the ambient. A deflector plate prevents the dust from eddying back into the separator.

Abstract: A foreign particle eliminating function and durability of an engine may be improved by an intake duct system having a cyclone duct including a cyclone module for generating torque of air, wherein the cyclone module includes: a central shaft; a plurality of cyclone blades that are formed outward from the central shaft; and a turbulence preventing device that is formed at a downstream side of the central shaft of the cyclone module so as to prevent turbulence of the air that has passed the cyclone blade.

Abstract: A vacuum cleaner comprises a cyclonic separator having a first cyclone and a plurality of downstream secondary cyclones. The first cyclone comprises a side wall defining a first cyclonic chamber, and the secondary cyclones each comprise a side wall defining a second cyclonic chamber. A dirt cup assembly is mounted below the cyclonic separator to collect contaminants separated in the first and second cyclonic chambers. The secondary cyclones can be arranged around the first cyclone side wall and form a gap between adjacent secondary cyclones so that the first cyclone side wall is exposed at the gap. A working air conduit can extend through the first cyclone and the dirt cup assembly to couple the secondary cyclones to a suction source located below the dirt cup assembly. Furthermore, the secondary cyclones can have a vortex stabilizer.

Abstract: A cyclonic vacuum cleaner includes a body portion, a nozzle portion and a dirt cup which is removable from the body portion. The dirt cup collects dirt and other debris separated by a cyclone and a cyclone slinger portion in the body portion. A main filter may be housed in a transparent filter door downstream of the cyclone. The dirt cup may be inserted into and sealingly held within the body portion by using a rotational camming structure.

Abstract: This invention discloses a subsection dedusting device for a vacuum cleaner comprising an upper cyclone separator including a wind outlet and several lower cyclone separators located below said upper cyclone separator, wind inlets of said lower cyclone separators in fluid communication with said wind outlet of said upper cyclone separator, thereby increasing wind quantity while reducing the whole bulk of the machine, and keeping a relatively high dedusting efficiency, and besides the lower cyclone separator of the present invention adopts a pervasion construction, and air flow rotates in a decelerated and acentric state in the conical barrel, thereby the pressure loss of the air flow is little, and accordingly, obtain a good dust suction effect.

Abstract: A condensate filter, particularly for pneumatic classification modules, is suggested, which has a condensate container (10) having a filter system (19), a twist device (15), which sets the incoming air into rotation at the upper air inlet (14), and a partition plate (16), which divides the container interior into an upper filter chamber (17) containing the filter system (19) and a lower condensate collection chamber (18). The condensate collection chamber (18) is provided on the lower end with a condensate outlet (12). A peripheral wall region (24) of the pot-like partition plate (16) enlarges conically in diameter downward to the contact on the inner circumference of the condensate container (10) and has multiple condensate passage openings (25) extending up to the contact edge.

Abstract: A gas-liquid separator for a fuel cell system onboard a vehicle includes an upper chamber, a lower chamber, a plate for separating the upper and lower chambers, a pipe for circulating the exhaust gas and connecting holes bored in the plate. The upper chamber receives exhaust gas from the fuel cell system to separate water contained in the exhaust gas. The lower chamber has a portion for discharging the water which is separated by the upper chamber. The pipe, which is attached to the upper chamber, has fluid communication with an inside of the upper chamber. The connecting holes provide fluid communication between the upper and lower chambers. The connecting holes are positioned off a center of the plate so that the connecting holes lie apart from the pipe.

Abstract: An air deoiling element with a drainage line for discharging the separated liquids, in which the drainage line is integrally mounted to a support member.

Abstract: The multi-cyclone dust separating apparatus includes a first cyclone unit including a first outer tub with a first air inlet and a cylindrical element with a first air outlet, and whirling air from the first air inlet to separate dust therefrom, the cylindrical element being disposed in the first outer tub to form a first cyclone chamber, along with the first outer tub; a second cyclone unit including a plurality of cyclones, each having a second air inlet for drawing in dust-laden air from the first cyclone chamber, to provide a second dust separation; and a dust bin including a first dust collecting chamber for collecting the dust separated by the first cyclone unit and a plurality of second dust collecting chambers for collecting the dust separated by the second cyclone unit.

Abstract: An air filter for electric welding includes a box having an opening for connecting with a sucking tube, an dividing plate dividing the box into an upper chamber communicating with the opening and a lower chamber, a spark blocker inside the upper chamber, a movable filter device set under the spark blocker inside the upper chamber and provided with a cloth filter, a blower inside the lower chamber, and an extractable screening device installed outside it and communicating with the lower chamber. In using, when the blower is switched on, the air is sucked in from the sucking tube to the spark blocker, the movable filter device, the blower and the extractable screening device orderly, blocking sparks completely and achieving an effective filtration.

Abstract: An upright vacuum cleaner includes a nozzle base having a main suction opening formed in an underside thereof. A housing is hingedly connected to the nozzle base. The housing includes a dirt separation chamber and a dirt receptacle for receiving dirt and dust separated by the dirt separation chamber. A conduit connects the nozzle base to the housing. A suction source is located in one of the housing and the nozzle base. The suction source is in fluid communication with the dirt separation chamber. A generally conically shaped filter extends into the dirt separation chamber along a longitudinal axis of the dirt separation chamber.

Abstract: A bagless vacuum cleaner system dustcup assembly and method for using said system with a vacuum cleaner apparatus to separate dirt from a mixture of dirt and air inducted into said vacuum cleaner apparatus. Said bagless vacuum cleaner system generally comprises a dustcup assembly, a handle assembly and a motor intake adaptor.

Abstract: A cyclone dust separator for a vacuum cleaner, where a couple of cyclones are disposed parallel with each other and sequentially operated to separate and collect dust. The cyclone dust separator includes a bypass path guiding dust-laden air drawn in through a suction opening directly to a motor and having a first mesh that filters off dust included in drawn-in air; a first cyclone disposed at one side of the bypass path to separate the dust from the dust-laden air drawn in through the suction opening and discharge cleaned air to the motor; and a second cyclone disposed parallel with the first cyclone to separate the dust from the dust-laden air drawn in through the suction opening and discharge cleaned air to the motor. The dust included in the air is separated sequentially by the first mesh, the first cyclone and the second cyclone.

Abstract: A cyclone dust-separating apparatus includes a cyclone unit having air inflow and air outflow parts that separate dust or dirt from air, the cyclone unit being installed such that a longitudinal axis thereof is substantially horizontally arranged; a dust bin joined to a bottom end of the cyclone unit that collects the dust or dirt separated by the cyclone unit, the dust bin installed in such a manner that a longitudinal axis thereof is substantially perpendicular to the longitudinal axis of the cyclone unit; a nonporous envelope detachably disposed in the dust bin that stores the dust or dirt collected into the dust bin; and a pressure difference-generating passage to communicate an outlet of the air outflow part and the dust bin with each other so as to allow the nonporous envelope to come in contact with an inner surface of the dust bin by a pressure difference between the dust bin and the air outflow part.

Abstract: A dust separating apparatus is provided, including a main body having a cylindrical shape and including a suction port on a bottom surface and an open upper part, a cover that covers the upper part of the main body and includes a discharge port formed on the same axis as the suction port; and an air guide member protruding from the suction port to the inside of the main body, wherein the air guide member allows the suction port to be in fluid communication with the main body when suction force is generated in the main body and does not allow the suction port to be in fluid communication with the main body when suction force is not generated in the main body.

Abstract: An air induction system for an engine to remove contaminants from intake air prior to delivery to the engine. The system includes a filtering unit having barrier filter panels attachable to a mounting frame. The filter panels are interchangeably usable. A juncture between first and second filter panels and the mounting frame is located at a region of relatively lower quantity of intake air flow. The juncture includes lugs on the filter panels which facilitate interchangeability. An opening above the filtering unit permits easy installation and removal of filter panels.

Abstract: A filter element, a safety element and fluid cleaner assembly. The fluid cleaner assembly generally includes a housing having a cover and a primary fluid cleaner section. The element generally comprises z-filter media, arranged in a straight through configuration, and an axial seal gasket positioned to extend continuously around at outer perimeter of the straight through flow construction. The fluid cleaner assembly can have a precleaner positioned therein. Methods of assembly and use are provided.

Abstract: A cyclone system for a vacuum cleaner includes an array of two or more primary cyclone chambers, an array of two or more secondary cyclone chambers situated downstream of the primary cyclone chambers, and a manifold situated downstream of and communicating with the primary cyclone chambers and upstream of and communicating with the secondary cyclone chambers.

Abstract: The present invention relates to a device for treating a gas/liquid mixture, comprising: —an upright vessel (1) with a lower and upper compartment; —an inlet (2) for admitting the flow of mixture into the lower compartment; —an agglomerating unit (10) placed between the lower and upper compartment for enlarging the liquid droplets in the mixture; —a lower outlet (4) for discharging the substantially liquid-containing mixture part from the lower compartment; —an upper outlet (5) for discharging the substantially gas-containing mixture part from the upper compartment; characterized by —collecting means (11) for collecting on the downstream side of the agglomerating unit liquid droplets which have broken through the agglomerating unit; —recycling means (12) for recycling the collected liquid to the lower compartment from the collecting means.

Abstract: A dust collecting unit of a vacuum cleaner is provided. The dust collecting unit includes: a plurality of storing chambers and a plurality of filtering chambers provided in the inside of a multi-cyclone dust collecting unit. To improve reliability of the product, the storing chambers and the filtering chambers are integrally formed as one body.

Abstract: A dust collection assembly of a vacuum cleaner is provided. The dust collection assembly includes a dust collecting box, a filter, a flow guide unit, an exhaust guider, and an upper cover. The dust collecting box and the flow guide unit are integrally formed in a single body. The dust collecting box includes a first and second dust collecting spaces for collecting foreign objects. The filter is disposed in the inside of the dust collecting space to primarily filter foreign objects during operation of a cyclone. The flow guide unit guides airflow and has small cyclones integrally formed therein, for secondarily filtering the foreign objects in air. The exhaust guider guides airflow and has a plurality of discharge holes through which air filtered by the small cyclone flows. The upper cover is disposed on the upper side of the exhaust guider.

Abstract: A dust collection unit for a vacuum cleaner includes a collection body having a plurality of filtering chambers different from each in a volume and a plurality of storing chambers storing foreign objects filtered in the filtering chambers, a bottom seal member defining a bottom of the collection body, and an exhaust member guiding airflow in the filtering chambers. The exhaust member contacts tops of the filtering chambers as well as an outer circumference of the collection body.

Abstract: A cyclonic separating apparatus includes a chamber for separating dirt and dust from an airflow, an inlet to the chamber and a shroud. The shroud includes a wall having inner and outer surfaces and a multiplicity of through-holes forming an outlet from the chamber. Each through-hole has an axis. The inner surface of the wall has a serrated profile having a plurality of serrations arranged around at least a part of the circumference of the wall, each serration having a first face and a second face. At least one through-hole passes through the first face of at least one serration. By providing a plurality of serrations around the inner circumference of the wall, the airflow is forced to follow a longer path through each through-hole for when compared to conventional arrangements. This reduces the amount of dirt and dust which is able to pass through the shroud.

Abstract: A vacuum cleaner including multiple cleaning stages comprises a first cyclonic stage and a second cyclonic stage, which is spaced from the first cyclonic stage. A housing defines a first particle collector that communicates with the first cyclonic stage. The first particle collector includes an opening. A removable lid covers the first particle collector opening. A second particle collector in communication with the second cyclonic stage is removable with the lid. A suction motor is supported by the vacuum cleaner. The suction motor establishes and maintains a flow of air through the vacuum cleaner.

Abstract: A device for collecting particles and microorganisms present in ambient air, the device comprising means for sucking air into a small volume enclosure in which the particles and microorganisms are separated from the sucked-in air by centrifuging, the device being portable, self-contained, and capable of being handled in one hand only, e.g. by means of a handle associated with the air suction means.

Abstract: A powered air cleaning system (31) and air cleaning method are disclosed. The system comprises a flow path (22) extending through the system from an air inlet (4) to a clean air outlet (5). A motor-driven fan (24) located along the flow path draws particulate debris laden air into the inlet and rotates it about an axis (A-A) to form a rotating flow that stratifies the debris laden air with the heaviest particles in the outermost orbits of the rotating flow. An ejector port (33) is provided for ejecting particulate debris laden air from the stratified rotating flow in the system to the environment. An air filter (9) located within the rotating flow and across the flow path upstream of the outlet filters air from the innermost orbits of the stratified rotating flow.

Abstract: A filter system for a surface maintenance machine having a hopper assembly for receiving brush-thrown debris including a cyclonic separator for separating dust and debris from air drawn through the hopper via vacuum action. The cyclonic separator may include multiple cyclone and may be in fluid communication with the hopper assembly so as to periodically receive dust and debris exiting the filter system.

Abstract: A filter element for removing material that is entrained in a gas stream comprises a wall of a filtration medium which defines a hollow space, for a gas stream to flow from the space through the wall. The filter element includes an end cap having an inlet tube for a gas stream to be supplied to the space. The tube has at least one helically extending rifle formation in its internal wall by which a helical flow is imparted to the gas stream when it leaves the tube.

Abstract: A dust collection unit for a vacuum cleaner includes a first cylindrical filtering chamber for filtering foreign objects contained in air using a cyclone airflow, a plurality of second filtering chamber formed along an outer circumference of the first cylindrical filtering chamber to receive the air passed through the first cylindrical filtering chamber, a first storing chamber formed under the first filtering chamber to store the foreign objects filtered in the first filtering chamber, a second storing chamber for storing the foreign objects filtered in the second filtering chambers, and a connection plate interconnecting opposite ends of the second storing chamber to define the first filtering chamber, the connection plate having a lower end located to be higher than a lower end of the second storing chamber.

Abstract: An extractor for a vacuum cleaning system of the type based on a cyclonic separator. The extractor comprises an annular body located adjacent the cyclonic separator and has an annular opening communicating with the cyclonic separator. A mesh covers the annular opening. In use the air circulating in the cyclonic separator vents through the extractor but debris in the air stream is stopped by the mesh.

Abstract: A bagless vacuum cleaner system dustcup assembly and method for using said system with a vacuum cleaner apparatus to separate dirt from a mixture of dirt and air inducted into said vacuum cleaner apparatus. Said bagless vacuum cleaner system generally comprises a dustcup assembly, a handle assembly and a motor intake adaptor.

Abstract: The invention relates to a gas intake zone of a separable gas filter housing which removably accommodates a filter element. The gas intake zone is used as a prefilter and comprises a plurality of axially adjacent, axially impinged cyclone collectors that are provided with respective spin generators in the inlet zones thereof and gas-discharging immersion tubes at the discharge end within annular ducts which are located between the immersion tubes and the respectively associated outer cyclone walls while being used for pre-separating dirt particles separated in an outer radial direction in the individual cyclones by means of centrifugal forces, the immersion tubes being axially dipped into the interior of the cyclone collectors. The aim of the invention is to be able to efficiently produce the gas intake zone while especially making the same easy to clean. The aim is achieved by a prefilter which is characterized in that all cyclones are composed of a unit encompassing three areas, i.e.

Abstract: A filter, comprising: a plurality of individual elongated members arranged into a configuration, each of the plurality of elongated members having an internal cavity extending completely therethrough, the plurality of individual elongated members being formed from a filter media for filtering a fluid, the filter having a first end and a second end defined by the ends of the plurality of individual elongated members and a plurality of areas defined between each of the plurality of individual elongated members, wherein fluid flow is blocked at the first end by sealing the plurality of areas at the first end with a sealing material and fluid flow is blocked at the second end by sealing the internal cavity of each of the plurality of individual elongated members at the second end with a sealing material, wherein fluid flow through the filter must pass through the filter media.

Abstract: A dust collecting apparatus for a vacuum cleaner has a first cyclone dust collecting part and a second cyclone dust collecting part that are arranged substantially parallel with respect to an air inflow opening of a vacuum cleaner main body, and may be mirror images of each other. The first cyclone dust collecting part comprises a first suction opening and a first discharge opening, and the second cyclone dust collecting part comprises a second suction opening and a second discharge opening. The first and second suction openings are connected with the air inflow opening of the vacuum cleaner main body, and the first and second discharge openings are connected with a vacuum suction chamber of the vacuum cleaner main body. Accordingly, a dust collecting apparatus for a vacuum cleaner can be realized, having an advanced suction capability and dust separation capability.

Abstract: A surface cleaning apparatus is disclosed. In some embodiments, the surface cleaning apparatus comprises a member having a dirty fluid inlet. A fluid flow path extends from the dirty fluid inlet to a clean air outlet of the surface cleaning apparatus, and includes a suction motor. At least a first air cleaning unit comprising a cyclonic cleaning stage is positioned in the fluid flow path. A material collection chamber is in flow communication with the at least one cyclone and is adapted to receive a liner bag. A vacuum line extends between the fluid flow path and an interior of the material collection chamber and is connectable in flow communication with the fluid flow path. A valve is associated with the vacuum line and moveable between a first position in which the vacuum line is open and a second position wherein the line is closed.

Abstract: A filter includes a filter element formed of filter media, and a plastic framework molded and bonded to and structurally supporting the filter media. One embodiment desirably provides a two-component assembly consisting solely of two components, namely the filter media and the plastic framework molded thereon. In a further embodiment, the plastic framework includes a resilient seal integrally molded therewith and of the same plastic material thereof, eliminating a separate component for the seal. In a further embodiment, a filter combination includes a primary filter element and a secondary filter element. In a further embodiment, a resilient integrally. molded seal is provided.

Abstract: A dust collecting unit for a vacuum cleaner is provided. The dust collecting unit includes a dust separating chamber with an air inlet formed on an outer surface thereof and an air outlet formed on one side thereof, a main dust collecting chamber formed in the dust separating chamber for separating dust and dirt in a cyclonic fashion, an auxiliary dust collecting chamber formed at one side of the main dust collecting chamber, and a partition plate for partitioning the main dust collecting chamber. The dust collecting unit allows an amount of air sucked and the efficiency of collecting dust and dirt to be greatly increased.

Abstract: An upright vacuum cleaner comprises a housing having a suction airstream inlet and a suction airstream outlet. A dirt container is selectively mounted to the housing for receiving and retaining dirt and dust separated from the suction airstream. The suction airstream inlet and the suction airstream outlet are in fluid communication with, respectively, an inlet and an outlet of the dirt container. The dirt container includes a first cyclonic airflow chamber and a second cyclonic airflow chamber, each cyclonic airflow chamber including a longitudinal axis. The second cyclonic airflow chamber is spaced from the first chamber, wherein the first and second chambers are each approximately vertically oriented and are arranged in a parallel relationship. An air manifold is disposed at a top portion of the dirt container. The air manifold includes an inlet section through which dirty air passes and an outlet section.

Abstract: A dust separating apparatus for a vacuum cleaner is provided. The dust separating apparatus comprises a first dust separating unit having a suction port, a guide member spirally, and a main filter to collect dust separated from drawn-in air, a second dust separating unit including a plurality of cyclones annularly arranged to centrifugally separate the dust from the air discharged from the first dust separating unit, and a cover unit to guide the air discharged from the first and the second dust separating units. The first dust separating unit separates the dust included in drawn-in air by rotating along the guide member and passing through the main filter the air drawn in through the suction port. The second dust separating unit rotates the air discharged from the first dust separating unit, thereby further filtering the air.

Abstract: Disclosed related to a dust collector of a vacuum cleaner comprising a dust separation part separating dust from the air; a dust collecting body having a dust storage part storing the dust separated by the dust separation part; and a division part dividing an inner space of the dust separation part and the dust storage part, opening and closing the dust separation part selectively, and having an opening discharging the dust into the dust storage part.

Abstract: A surface cleaning apparatus comprises two or more side-by-side housings, which contain operating components of the surface cleaning apparatus, such as fluid cleaning members or one or more fluid cleaning members and the suction motor of the cleaning apparatus, to provide a cleaning apparatus having a reduced height.

Abstract: A cyclone dust collecting device, for use in a vacuum cleaner, includes a housing defining therein a cyclonic air flow chamber. A dust collection chamber is disposed under the cyclonic air flow chamber and a partition wall is disposed between the cyclonic air flow chamber and the dust collection chamber. An opening and at least one ventilation hole are provided in opposite sides of the partition wall, respectively, so that a part of air and dust vortically moving in the cyclonic air flow chamber are introduced into the dust collection chamber through the opening and the air in the dust collection chamber flows back into the cyclonic air flow chamber through the ventilation hole.

Abstract: A filter cup having a shell with a plurality of apertures in an upper portion and an aperture free portion below the upper portion. A base plate adjacent the aperture free portion has at least one aperture therethrough.

Abstract: A centrifugal separator device (10) for separating solid and/or liquid particles which are suspended in gas media, which device comprises a rotor (12) which is provided sedimentation members (14), which is rotatably mounted in a surrounding stationary housing (20) and which has a central inlet for the gas medium which is to be cleaned. The housing (20) has, on the one hand, an outlet (32) for cleaned gas which, during its passage through the sedimentation members (14) in the rotor (12), has been freed form solid and/or liquid particles, and, on the other hand, an outlet (28 a-c) for solid and/or liquid particles which have been transferred onto the inner side of the housing.

Abstract: The invention relates to a separation assembly for separating dirt and dust from air in a vacuum cleaner (1), through which assembly an air flow path extends from an inlet (5) to an outlet (6). The air flow path extends through an upstream separator (18) and a downstream separator (19). The downstream separator (19) includes an air-permeable filter element (28) bounding an inner space (27). The wall sections bounding the air flow path in the area of the downstream separator include at least a transparent section (30) through which the filter element (28) is visible. The inner space (27) is located upstream of an area (31) outside the filter element (28) for filtering air flowing from inside the filter element (28) to outside the filter element (28).