Filter unit for the suction connection in the waste water tank of a floor cleaning machine

Abstract

A filter unit (37) is shown and described for use in the suction pipe (31) of a floor cleaner (1), particularly for use in the suction pipe (31) of the wastewater tank (5) of the floor cleaner (1). The filter unit has: a generally sleeve-shaped base (39) extending between a first end (41) and a second end (43) and having an inlet opening (45) at the first end (41); a generally annular float (77) arranged around the base (39) and movable along the base (39) between a closed position and an open position; a cover (57) arranged at the first end of the base, wherein the cover (57) has at least one inlet opening (59); and a sleeve-shaped filter element (69) arranged around the base (39) in such a way that an annular space (79) is formed between the base (39) and the filter element (69).

Description

Technical Field

[0001] The present invention relates to a filter unit for a suction or extraction pipe in a wastewater tank of a floor cleaning machine, and a floor cleaning machine, particularly a vacuum cleaner, having such a filter unit. Background Technology

[0002] Existing floor cleaning machines or extractors, which can move across a surface to be cleaned by means of a traveling mechanism, have brush heads equipped with driven brushes that engage with the surface to be cleaned. Cleaning fluid is applied to the surface in the brush head area to remove dirt adhering to it. Viewed along the direction of travel of the extractor, a so-called suction squeegee is typically arranged behind the brush head, by means of which the cleaning fluid previously applied to the surface to be cleaned is drawn back into the machine's waste tank. For this purpose, a suction turbine is provided, which is connected to the interior of the waste tank via a suction pipe to create negative pressure in the waste tank. The suction line is further guided from the interior of the waste tank to the suction squeegee, thereby applying negative pressure to the suction area of ​​the suction squeegee through the suction turbine. This, in turn, enables the generation of a suction airflow from the suction squeegee to the waste tank, through which the cleaning fluid on the surface to be cleaned is carried into the waste tank.

[0003] A disadvantage here is that foam, the wastewater itself, and contaminant particles contained in the wastewater or suction airflow can enter the suction turbine, as both can potentially damage the suction turbine or the motor driving it. Therefore, it is also known from the prior art to install a filter unit on the suction inlet to prevent at least some contaminant particles from entering the suction inlet and thus the suction turbine. Furthermore, it is known to install a float valve on the suction inlet, which closes the suction inlet when the liquid level in the wastewater tank reaches a preset maximum level.

[0004] However, such filter units and float valves known from the prior art have proven disadvantageous because they generally cannot guarantee that the user will reassemble the filter unit correctly so that, after cleaning, the filter unit and float valve are accurately positioned and prevent dirt or cleaning fluid from passing through and reaching the suction turbine. Furthermore, filter units and float valves known from the prior art cannot reliably prevent foam from entering the suction turbine. Summary of the Invention

[0005] Therefore, the object of the present invention is to provide a filter unit for the suction pipe in the wastewater tank of a floor cleaning machine, the filter unit having a valve and being reliably and easily assembled. Furthermore, it is desirable that the filter unit also reliably prevents foam from entering the suction turbine.

[0006] According to the invention, this objective is achieved by a filter unit for a suction nozzle of a floor cleaner, particularly for a suction nozzle in a wastewater tank of a floor cleaner. The filter unit has a generally sleeve-shaped base extending between a first end and a second end, and having an inlet opening at the first end. The filter unit also has a generally annular float arranged around the base and movable along the base between a closed position and an open position. Furthermore, the filter unit has a cover arranged at the first end of the base, wherein the cover has at least one inlet opening designed such that the inlet opening is closed by the float when the float is in the closed position, and open when the float is spaced apart from the closed position. A fluid channel is provided in the cover, designed to allow fluid to flow from the inlet opening into the inlet opening. The filter unit also has a sleeve-shaped filter element arranged around the base such that an annular space is formed between the base and the filter element, in which the float is movable between the closed and open positions. The filter element is at least partially composed of a filter material, allowing fluid to pass through it while particles contained in the fluid are deposited on the filter material. The filter material may be arranged on the circumferential surface of the filter element.

[0007] The filter unit according to the invention, equipped with a float valve, can be placed in a simple manner onto the suction port in the wastewater tank of the scrubbing machine, in which the sleeve-shaped substrate is pushed onto the suction port.

[0008] However, according to the invention, it is also conceivable that the substrate is part of the suction tube and, in some cases, even formed as a single piece with it.

[0009] As the water level in the wastewater tank rises during or immediately after the operation of the surface suction machine, causing the float to rise continuously in the annular space, the float can close the inlet opening (closed position). Closing the inlet opening prevents wastewater from entering the downstream suction turbine and causing damage. When the inlet opening is closed by the float, this can be indicated to the user of the suction machine, in one way: the reduced motor current of the suction turbine due to the closure triggers a corresponding signal for the user. Alternatively, it is conceivable that the float actuates a switch or non-contact sensor, thereby generating a corresponding signal for the user.

[0010] A similar effect can be achieved if the water level in the wastewater tank fluctuates drastically during the operation of the suction machine and the float rises sharply only for a short period of time. The inlet opening is then sealed, and this can be indicated to the user. This also ensures that no wastewater reaches the suction turbine.

[0011] Furthermore, the filter element (which defines the annular space around the substrate) prevents contaminant particles contained in the suction airflow from passing through the inlet opening and reaching the suction turbine. When the filter element or the filter material disposed thereon is so heavily contaminated that only a small amount of airflow passes through, this can also cause the float to be pulled toward the inlet opening and close it. This can then be indicated to the user using the possibilities already described.

[0012] Because the floats are arranged in an annular space and guided by the base, a compact structure is achieved overall. The floats are held firmly to the base without being lost, so that the floats will not be lost when the filter elements are removed for cleaning. This may result in the filter elements being cleaned and the system being restored to operation. If the water level in the wastewater tank is too high, the sealing effect may no longer be effective and wastewater may enter the suction turbine without obstruction.

[0013] In a preferred embodiment, the filter element is detachably secured to the cover. The filter element can be detached from the cover, cleaned, and reused. Here, the filter element may preferably have a handle to simplify separation from the cover. The size or inner diameter of the filter element may be adapted to the cover in such a way that the filter element is secured to the cover with a transition fit or slight press fit to prevent loss, for example, when tilting the waste tank for maintenance. This embodiment is particularly easy to assemble and / or maintain.

[0014] In another preferred embodiment, the substrate has an outwardly extending annular flange that abuts the float when it is in the open position, and the filter element extends to the flange. The flange can serve as a stop, especially after the cleaning process, when the filter element is mechanically connected. Furthermore, the flange prevents sub-flows of the suction airflow from bypassing the filter element and entering the annular space.

[0015] In a further preferred embodiment, the flange may have at least one opening or flange opening that is closed by the float when it is in the open position and released when the float moves from the open position toward the closed position. The flange opening provides another flow path into the annular space, and the flow through the flange opening facilitates the movement of the float to the closed position. The flange opening enhances the protection provided by the filter unit, especially when the filter element becomes increasingly contaminated or when foam forms in the wastewater tank. This embodiment allows air to flow through the flange opening in the event of filter element blockage, and this air can compress the float to its closed position. Finally, the flange opening also allows foam that may be present in the wastewater tank to move the float toward the closed position as well. Thus, in this way, foam forming above the wastewater level and potentially posing a danger to the suction turbine also prompts the float to close the opening, protecting the suction turbine and thus instructing the user.

[0016] In another preferred embodiment, the substrate has at least one locking element, preferably at least one locking hook, in the region of the inlet opening. This at least one locking element is designed to engage with at least one engaging element on the suction tube. The substrate and cover are designed to provide a fluid connection between the inlet opening and the suction tube when the at least one locking element engages with the engaging element. The substrate and cover can be designed such that when the at least one locking element engages with the engaging element of the suction tube, fluid can flow into the suction tube through the inlet opening of the cover and through the inlet opening of the substrate. In this embodiment, the filter unit can be simply mounted on the suction tube.

[0017] In a further preferred embodiment, a locking body may be provided, wherein the locking body has a cylindrical section, and wherein the cylindrical section is inserted into the inlet opening and is designed to prevent the locking element from disengaging from the suction tube. In this embodiment, the base is securely connected to the suction tube after the locking body is inserted. Furthermore, the locking body can suppress any lack of a seal between the base and the suction tube.

[0018] In a particularly preferred embodiment, the locking body may have a surrounding flange that extends beyond the base into the annular space. A float may abut against the flange in the closed position. The flange may help define the closed position. A cover may be mechanically connected to a first end of the base and therein clamp the flange of the locking body.

[0019] In a preferred embodiment, the cover and the base can be independent components, with a locking body, particularly a flange of the locking body, arranged between the cover and the base. In this embodiment, the filter unit can be assembled as follows: First, the base is placed onto the suction pipe, where the locking element engages with the suction pipe. Then, the locking body is inserted into the inlet opening of the base, preventing the locking element from separating from the suction pipe and thus locking the base onto the suction pipe. The cover is then fastened to the base, making it impossible for the locking body to separate from the base. The base can only be separated from the suction pipe by removing the cover and then removing the locking body from the inlet opening. Thus, this structure allows for a simple and secure fastening of the base onto the suction pipe. Furthermore, when the filter element is removed, for example, to clean the cover and base, the flange of the locking body ensures that the float does not separate from the base and is lost.

[0020] In another preferred embodiment, a resilient annular element is provided that abuts against the plane of the substrate opposite to the cover, wherein the annular element is configured to abut against the suction nozzle. This embodiment is more resistant to vibrations during the operation of the floor cleaner. The resilient annular element can also be used to compensate for manufacturing tolerances, particularly between the substrate and the suction nozzle. Furthermore, the resilient annular element prevents leaks, particularly between the suction nozzle and the substrate.

[0021] Another preferred embodiment features a filter element with a sieve-like circumferential surface. This simplifies the cleaning of the filter element.

[0022] In another embodiment, the substrate has a tubular section around which a float can be arranged, wherein the tubular section can be fitted onto the suction port of the floor cleaning machine. The substrate can be simply arranged and centered relative to the suction port.

[0023] According to another aspect of the invention, the above-mentioned objective is achieved by a floor cleaning machine, particularly a vacuum cleaner, comprising: a wastewater tank; a suction pipe extending into the wastewater tank; a suction turbine connected to the end of the suction pipe opposite to the wastewater tank in a fluid-guiding manner, for generating negative pressure in the wastewater tank; and a suction line terminating in the wastewater tank, connected to a device for extracting liquid from the floor to be cleaned by means of negative pressure. The floor cleaning machine includes the aforementioned filter unit, which is mechanically connected to the end of the suction pipe disposed in the wastewater tank.

[0024] The floor cleaning machine or extractor according to the invention may in particular have a traveling mechanism by which the floor cleaning machine or extractor can move on the floor to be cleaned, wherein, in a further preferred manner, a cleaning device is provided on the machine, which can engage with the floor to be cleaned and can apply cleaning fluid to the floor.

[0025] In this regard, it should be noted that the present invention can be applied to both autonomous floor cleaning machines or vacuum cleaners in which users ride on the machine, and machines in which users walk in front of or behind the machine.

[0026] The floor cleaning machine may have a current detector that can detect the current intensity drawn by the suction turbine.

[0027] During the operation of a floor cleaner, the fill height in the wastewater tank may exceed its maximum value, potentially leading to unwanted foam buildup and / or increasing clogging of the filter elements in the filter unit. In these situations, the float can occupy a closed position, particularly due to the openings in the flanges of the base, preventing undesirable liquid entry into the suction turbine. Because it is in a closed position, the power consumption of the suction turbine changes, and this current change can be identified as a knee or discontinuity in the current-time curve. Based on this current change, a signal can be sent to the user, prompting the user to maintain the floor cleaner, i.e., clean the filter and / or empty the wastewater tank. Alternatively, it is conceivable to detect whether the float is in a closed position via a switch or a non-contact sensor. Here, a corresponding signal can also be generated to indicate closure to the user. Attached Figure Description

[0028] The invention is described below with the aid of the accompanying drawings, which show only preferred embodiments, wherein...

[0029] Figure 1 A longitudinal section is shown of an embodiment of a washing machine having a filter unit according to the invention;

[0030] Figure 2 An embodiment of the filter unit according to the invention is shown in cross-section; and

[0031] Figure 3 Show in 3D Figure 2 Examples of implementations. Detailed Implementation

[0032] Figure 1 A floor cleaner 1 is shown as an embodiment of a floor cleaner. The floor cleaner 1 has a wastewater tank 5 within its housing 3, which can be closed by a cover element 7 pivotally fixed to the housing 3. Furthermore, the floor cleaner 1 is equipped with a travel mechanism with wheels 9, allowing the floor cleaner 1 to move on the floor 11 to be cleaned. (As shown in...) Figure 1As can be further seen, a brush head 13 is mounted on the housing 3 at an adjustable height. In the preferred embodiment shown here, the brush head 13 has a rotating brush element 15 that can engage with the floor 11 to be cleaned to remove dirt from the floor. During the cleaning process, cleaning fluid from a water tank 17 (shown schematically) also located in the housing 3 is applied to the floor 11 to be cleaned.

[0033] exist Figure 1 As can also be seen in the embodiment described herein, a suction nozzle 19 is mounted on the housing 3 of the floor cleaner. This suction nozzle serves as a suction device for removing cleaning fluid remaining on the floor 11 to be cleaned. The suction nozzle 19 is designed in a manner known per se to have two spaced-apart sealing lips that are placed at their edges on the floor 11 to be cleaned during cleaning operations. The sealing lip pointing in the direction of travel has an inlet groove that allows previously applied cleaning fluid to enter the area between the sealing lips. The area between the sealing lips is connected to a wastewater tank 5 via a suction conduit 21 and an inlet port 23, wherein the inlet port 23 extends into the wastewater tank 5.

[0034] Furthermore, the suction machine 1 has a suction turbine 25 within the housing 3, which has a drive motor 27 and a fan impeller 29 (shown schematically) driven by the drive motor. The inlet of the suction turbine 25 is connected to the interior of the wastewater tank 5 via a suction pipe 31, wherein the free end 33 of the suction pipe 31 is provided with an undercut 35 (see...). Figure 2 and Figure 3 The undercut portion 35 forms a connecting element here.

[0035] A filter unit 37 according to the invention is installed at the suction connector 31 and at the free end 33 of the suction connector. Figure 2 and Figure 3 The following is a detailed example.

[0036] The filter unit 37 has a base 39, which, in the preferred embodiment shown herein, is configured in a columnar and sleeve-like shape and surrounds the upper portion of the suction tube 31, wherein the base 39 extends between a first end 41 and a second end 43. Furthermore, the base 39 has an inlet opening 45 at the first end 41, wherein a shoulder 47 is provided in the region of the inlet opening 45, extending into the inlet tube 31 such that the shoulder 47 extends generally parallel to the outer wall 49 constituting the tubular section of the base 39. Furthermore, the base 39 has a circumferential flange 51 in the region of the second end 43, which extends outward away from the outer wall 49 and is disposed in a flange opening 53. Additionally... Figure 2 and Figure 3As can be seen, in the region of the first end 41, there is a locking hook 55 at the inlet opening 45. When the substrate 39 is placed on the suction tube 31, these locking hooks engage with the undercut 35, thereby preventing the substrate 39 from detaching from the suction tube 31.

[0037] Furthermore, the filter unit 37 has a cover 57, which is fastened to the base 39 on the side of the first end 41 opposite to the direction pointed to by the suction tube 31. In the preferred embodiment, the cover 57 has a circumferential inlet opening 59, and the cover 57 is also designed to have a fluid channel 61 in the cover. The inlet opening 59 is connected to the inlet opening 45 in the base 39 via the fluid channel, so that fluid (such as air) can enter the fluid channel 61 through the inlet opening 59 and then enter the suction tube 31 through the inlet opening 45.

[0038] Furthermore, the filter unit 37 has a locking body 63 including a columnar section 65, which is designed to be inserted into the inlet opening 45 and shoulder 47 of the base 39, thereby preventing the locking hook 55 from pivoting inward and thus potentially disengaging from the undercut 35. Therefore, the columnar section 65 prevents the base 39 from potentially separating from the suction tube 31. Additionally, a flange 67 is provided on the locking body 63, which extends outward along the first end 41 of the base 39. The locking body 63 is thus clamped between the base 39 or its first end 41 and the cover 57.

[0039] The filter unit 37 also has a sleeve-shaped filter element 69, the columnar section 71 of which forms the circumferential surface is made of sieve-like filter material, and the filter element also has a connecting section 73 that is pushed onto the cover 57, wherein there is a press fit between the cover 57 and the connecting section 73, so that the filter element 69 cannot be easily detached from the cover 57. The columnar section 71 made of filter material extends to a surrounding flange 51 on the base 39, wherein a ring 75 is provided at the end of the columnar section 71 opposite to the connecting section 73, which engages with the surrounding flange 51.

[0040] Furthermore, the filter unit 37 has a generally annular float 77 arranged around the base 39, and particularly around the outer wall 49 of the base, wherein the float 77 can move along the base 39 or its outer wall 49 between a closed position and an open position. When the float 77 is in the closed position, it abuts against the flange 67 of the locking body 63 and closes the entry opening 59 in the cover 57, while in the open position, the float abuts against the circumferential flange 51 of the base 39 at its lower end and closes the flange opening 53 therein. Thus, the float 77 moves within the annular space 79 formed between the filter elements 69, 71 and the base 39. The float 77 is designed such that when the water level in the wastewater tank 5 rises, the float 77 moves along the base 39 toward the flange 67 of the locking body 63 and the entry opening 59 of the cover 57.

[0041] Finally, in the preferred embodiment described herein, an elastic annular element 81 is provided between the free end 33 of the suction connector 31 and the base 39. This elastic annular element is slightly compressed when the locking hook 55 engages with the undercut portion 35. This prevents the filter unit 37 from being damaged or separated from the suction connector due to vibration. Furthermore, the elastic annular element 81 compensates for manufacturing tolerances. The elastic annular element 81 also serves a sealing function.

[0042] An embodiment of the filter unit 37 according to the invention can be assembled onto the suction pipe 31 of the suction washing machine 1 in the following manner. First, the elastic annular element 81 and the base 39 are placed onto the suction pipe 31, wherein the locking hook 55 engages with the undercut portion 35. Then, the float 77 is pushed onto the base 39, wherein the float 77 surrounds the base 39 or its outer wall 49. Next, the locking body 63 is inserted into the inlet opening 45 and the locking hook 55 is locked in the engaged position. Furthermore, the accurate engagement of the locking hook is ensured by assembling the locking body. The flange 67 also prevents the float 77 from being removed. Then, the cover 57 is fastened onto the base 39, wherein the locking body 63 is clamped therein. Finally, the filter element 69 can be pushed onto the previously assembled assembly, wherein the press fit between the cover 57 and the connecting section 73 prevents the filter element 69 from easily separating.

[0043] During the operation of the suction scrubber 1, air carrying sewage and sludge is drawn from the suction head 19 through the suction pipe 21 and the inlet pipe 23 into the sewage tank 5 by means of the suction turbine 25. The air can pass through the columnar section 71 of the filter element 69 and then further through the inlet opening 59 and the inlet opening 45 to the suction turbine, where sludge particles are deposited on the columnar section 71. As the sewage level in the sewage tank 5 rises, the float 77 moves from... Figure 3The indicated position is moved further upward until it is so close to the inlet opening 59 of the cover 57 at a certain water level that the float is pulled towards the flange 67 of the locking body 63 by the airflow and closes the inlet opening 59. In this case, the power consumption of the suction turbine changes and indicates to the user that the sewage level in the sewage tank 5 is high enough that the tank must be emptied.

[0044] Furthermore, the flange opening 53 in the surrounding flange 51 of the substrate 39 allows foam to enter the annular space 79, which also causes the float 77 to move upward even when the sewage level itself is at a low level, thereby closing the inlet opening 59 and thus instructing the user to empty the sewage tank 5.

[0045] When the columnar section 71 of the filter element 69 is sufficiently contaminated, only a small amount of air can pass through it. This causes the float 77 to be drawn towards and closed by the airflow through the flange opening 53. In this case, the user must clean the filter element 69 by simply removing the connecting section 73 from the cover 57. However, the float 77 cannot be separated here because it remains clamped between the surrounding flange 51 and the flange 67.

[0046] This allows for simple assembly and cleaning of the filter unit 37, with no risk of loss of the float 77, especially when cleaning the filter unit 37 and removing the filter element 69, particularly due to the locking body 63. Furthermore, the filter unit 37 has a very compact structure, as it is arranged only around the suction pipe 31, and therefore occupies relatively little space in the wastewater tank 5.

[0047] List of reference numerals in the attached diagram:

[0048] 1. Extraction washing machine

[0049] 3. Shell

[0050] 5. Sewage tank

[0051] 7. Cover element

[0052] 9 wheels

[0053] 11 Ground

[0054] 13 Brush Heads

[0055] 15 Brush Components

[0056] 17. Clean Water Tank

[0057] 19. Suction head

[0058] 21 Suction tubing

[0059] 23 Inlet pipe

[0060] 25 suction turbines

[0061] 27 Drive Motor

[0062] 29. Ventilation fan impeller

[0063] 31 Suction Connector

[0064] 33 Free End

[0065] 35. Undercut

[0066] 37 Filter Units

[0067] 39 Matrix

[0068] 41 First end

[0069] 43 Second end

[0070] 45. Entrance opening

[0071] 47 shoulder

[0072] 49 outer wall

[0073] 51. Circumferential flange

[0074] 53. Flange opening

[0075] 55 Carabiner

[0076] 57 Cover

[0077] 59 Enter the opening

[0078] 61 Fluid Channel

[0079] 63 Locked Body

[0080] 65 columnar sections

[0081] 67 Flange

[0082] 69 Filter elements

[0083] 71 columnar section

[0084] 73 Connecting Section

[0085] 75 rings

[0086] 77 floating body

[0087] 79. Circular Space

[0088] 81. Elastic Ring Element

Claims

1. A filter unit (37) for a suction pipe (31) of a floor cleaning machine (1), said filter unit having: A generally sleeve-shaped base (39) extends between a first end (41) and a second end (43) and has an inlet opening (45) at the first end (41). A generally annular float (77) is arranged around the base (39) and is movable along the base (39) between a closed position and an open position; Cover (57), said cover is disposed at the first end of the base. in, The cover (57) has at least one inlet opening (59), which is designed such that when the float is in the closed position, the inlet opening is closed by the float (77); and when the float (77) is spaced apart from the closed position, the inlet opening is open, characterized in that a fluid channel (61) is provided in the cover (57), which is designed to allow fluid to flow from the inlet opening (59) into the inlet opening (45); and A sleeve-shaped filter element (69) is arranged around the substrate (39) in such a way that an annular space (79) is formed between the substrate (39) and the filter element (69), and a float (77) is displaceably arranged in the annular space between the closed position and the open position. The filter element (69) is at least partially composed of filter material (71) such that fluid can pass through the filter material (71) and particles contained in the fluid are deposited on the filter material (71).

2. The filter unit (37) according to claim 1, wherein, The filter element (69) can be loosely held in place on the cover (57).

3. The filter unit (37) according to claim 1 or 2, wherein, The base (39) has an outwardly extending circumferential flange (51), and when the float (77) is in the open position, the float (77) abuts against the circumferential flange, and The filter element (69) extends to the flange (51).

4. The filter unit (37) according to claim 3, wherein, The flange (51) has at least one flange opening (53) which is closed by the float (77) when the float (77) is in the open position, and is released when the float (77) moves from the open position toward the closed position.

5. The filter unit (37) according to any one of claims 1, 2 and 4, wherein, The base (39) has at least one locking element (55) in the region of the inlet opening (45), the at least one locking element (55) being at least one locking hook. The at least one locking element (55) is designed to engage with at least one engaging element (35) on the suction tube (31), and The base (39) and the cover (57) are designed to provide a fluid connection between the inlet opening (59) and the suction tube (31) when the at least one locking element (55) engages with the engagement element (35).

6. The filter unit (37) according to claim 5, having a locking body (63) having columnar sections (65). in, The columnar section (65) is inserted into the inlet opening (45) and is designed to prevent the at least one locking element (55) from disengaging from the suction tube (31).

7. The filter unit (37) according to claim 6, wherein, The locking body (63) has a flange (67) that extends beyond the base (39) into the annular space (79). When the float (77) is in the closed position, the float (77) is attached to the flange (67).

8. The filter unit (37) according to claim 6 or 7, wherein, The cover (57) and the base (39) are independent components, and The locking body (63) is arranged between the cover (57) and the base (39).

9. The filter unit (37) according to any one of claims 1, 2, 4, 6 and 7, having an elastic annular element (81) abutting against the plane of the substrate (39) opposite to the cover (57) and for abutting against the suction tube (31).

10. The filter unit (37) according to any one of claims 1, 2, 4, 6 and 7, wherein, The filter element (69) has a sieve-like circumferential surface.

11. The filter unit (37) according to any one of claims 1, 2, 4, 6 and 7, wherein, The substrate (39) has a tubular section (49), and the float (77) is arranged around the tubular section. The tubular section (49) can be fitted onto the suction pipe (31) of the floor cleaning machine (1).

12. The filter unit (37) according to claim 1, wherein, The filter unit (37) is used in the suction pipe (31) of the wastewater tank (5) of the ground cleaning machine (1).

13. A floor cleaning machine (1) comprising: a wastewater tank (5); A suction pipe (31) extends into the wastewater tank (5); A suction turbine (25) is connected to the end of the suction pipe (31) opposite to the sewage tank (5) in a fluid-guiding manner, which is used to generate negative pressure in the sewage tank (5); The suction line (21, 23) terminates in the wastewater tank (5), and is connected to a device (19) for drawing liquid from the surface (11) to be cleaned by means of negative pressure. in, The system includes a filtration unit (37) according to any one of claims 1 to 12, the filtration unit being mechanically connected to the free end (33) of the suction pipe (31) arranged in the wastewater tank (5).

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